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gEDA-cvs: pcb.git: branch: master updated (8f3fcd5ba0c4f26aae49fca59fa128141388b265)



The branch, master has been updated
       via  8f3fcd5ba0c4f26aae49fca59fa128141388b265 (commit)
      from  c9e069b19455c6e20b7988b86a4736f6ea0b1bc0 (commit)

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=========
 Summary
=========

 Makefile.am                    |    2 +-
 configure.ac                   |   27 +++++++++++++++++
 {src/gts => gts}/.gitignore    |    0 
 gts/Makefile.am                |   48 ++++++++++++++++++++++++++++++
 {src/gts => gts}/NOTES         |    0 
 {src/gts => gts}/bbtree.c      |    0 
 {src/gts => gts}/boolean.c     |    0 
 {src/gts => gts}/cdt.c         |    0 
 {src/gts => gts}/container.c   |    0 
 {src/gts => gts}/curvature.c   |    0 
 {src/gts => gts}/edge.c        |    0 
 {src/gts => gts}/eheap.c       |    0 
 {src/gts => gts}/face.c        |    0 
 {src/gts => gts}/fifo.c        |    0 
 {src/gts => gts}/graph.c       |    0 
 {src/gts => gts}/gts-private.h |    0 
 {src/gts => gts}/gts.h         |    0 
 {src/gts => gts}/heap.c        |    0 
 {src/gts => gts}/hsurface.c    |    0 
 {src/gts => gts}/iso.c         |    0 
 {src/gts => gts}/isotetra.c    |    0 
 {src/gts => gts}/kdtree.c      |    0 
 {src/gts => gts}/matrix.c      |    0 
 {src/gts => gts}/misc.c        |    0 
 {src/gts => gts}/named.c       |    0 
 {src/gts => gts}/object.c      |    0 
 {src/gts => gts}/oocs.c        |    0 
 {src/gts => gts}/partition.c   |    0 
 {src/gts => gts}/pgraph.c      |    0 
 {src/gts => gts}/point.c       |    0 
 {src/gts => gts}/predicates.c  |    0 
 {src/gts => gts}/predicates.h  |    0 
 {src/gts => gts}/psurface.c    |    0 
 {src/gts => gts}/refine.c      |    0 
 {src/gts => gts}/rounding.h    |    0 
 {src/gts => gts}/segment.c     |    0 
 {src/gts => gts}/split.c       |    0 
 {src/gts => gts}/stripe.c      |    0 
 {src/gts => gts}/surface.c     |    0 
 {src/gts => gts}/triangle.c    |    0 
 {src/gts => gts}/tribox3.c     |    0 
 {src/gts => gts}/vertex.c      |    0 
 {src/gts => gts}/vopt.c        |    0 
 src/Makefile.am                |   63 ++++-----------------------------------
 44 files changed, 83 insertions(+), 57 deletions(-)
 rename {src/gts => gts}/.gitignore (100%)
 create mode 100644 gts/Makefile.am
 rename {src/gts => gts}/NOTES (100%)
 rename {src/gts => gts}/bbtree.c (100%)
 rename {src/gts => gts}/boolean.c (100%)
 rename {src/gts => gts}/cdt.c (100%)
 rename {src/gts => gts}/container.c (100%)
 rename {src/gts => gts}/curvature.c (100%)
 rename {src/gts => gts}/edge.c (100%)
 rename {src/gts => gts}/eheap.c (100%)
 rename {src/gts => gts}/face.c (100%)
 rename {src/gts => gts}/fifo.c (100%)
 rename {src/gts => gts}/graph.c (100%)
 rename {src/gts => gts}/gts-private.h (100%)
 rename {src/gts => gts}/gts.h (100%)
 rename {src/gts => gts}/heap.c (100%)
 rename {src/gts => gts}/hsurface.c (100%)
 rename {src/gts => gts}/iso.c (100%)
 rename {src/gts => gts}/isotetra.c (100%)
 rename {src/gts => gts}/kdtree.c (100%)
 rename {src/gts => gts}/matrix.c (100%)
 rename {src/gts => gts}/misc.c (100%)
 rename {src/gts => gts}/named.c (100%)
 rename {src/gts => gts}/object.c (100%)
 rename {src/gts => gts}/oocs.c (100%)
 rename {src/gts => gts}/partition.c (100%)
 rename {src/gts => gts}/pgraph.c (100%)
 rename {src/gts => gts}/point.c (100%)
 rename {src/gts => gts}/predicates.c (100%)
 rename {src/gts => gts}/predicates.h (100%)
 rename {src/gts => gts}/psurface.c (100%)
 rename {src/gts => gts}/refine.c (100%)
 rename {src/gts => gts}/rounding.h (100%)
 rename {src/gts => gts}/segment.c (100%)
 rename {src/gts => gts}/split.c (100%)
 rename {src/gts => gts}/stripe.c (100%)
 rename {src/gts => gts}/surface.c (100%)
 rename {src/gts => gts}/triangle.c (100%)
 rename {src/gts => gts}/tribox3.c (100%)
 rename {src/gts => gts}/vertex.c (100%)
 rename {src/gts => gts}/vopt.c (100%)


=================
 Commit Messages
=================

commit 8f3fcd5ba0c4f26aae49fca59fa128141388b265
Author: DJ Delorie <dj@xxxxxxxxxxx>
Commit: DJ Delorie <dj@xxxxxxxxxxx>

    Add top-level build changes to enable C++ compilation
    
    This patch moves GTS (gts.sourceforce.net) out of the src/
    tree and gives it its own Makefile, and changes src/Makefile.am
    so that C++ compilation is used if configure requests it.
    
    ./configure --enable-build-with-cxx
    ./configure --disable-build-with-cxx
    
    (the default is disable at the moment)
    
    Makefiles with these lines will use C++ if the user requests it:
    
    CC = @CC_OR_CXX@
    CFLAGS = @CC_OR_CXX_FLAGS@

:100644 100644 f143862... 41ca65a... M	Makefile.am
:100644 100644 cf685a7... 13e0e07... M	configure.ac
:000000 100644 0000000... 8e051a6... A	gts/.gitignore
:000000 100644 0000000... ad7c938... A	gts/Makefile.am
:000000 100644 0000000... c697949... A	gts/NOTES
:000000 100644 0000000... cec93e4... A	gts/bbtree.c
:000000 100644 0000000... 8b76d42... A	gts/boolean.c
:000000 100644 0000000... 2038ab5... A	gts/cdt.c
:000000 100644 0000000... e1dc0fa... A	gts/container.c
:000000 100644 0000000... 70f6af2... A	gts/curvature.c
:000000 100644 0000000... fde7d87... A	gts/edge.c
:000000 100644 0000000... 29f462d... A	gts/eheap.c
:000000 100644 0000000... f6009f1... A	gts/face.c
:000000 100644 0000000... 8b3d2b6... A	gts/fifo.c
:000000 100644 0000000... 1566c95... A	gts/graph.c
:000000 100644 0000000... 59246d1... A	gts/gts-private.h
:000000 100644 0000000... 9397230... A	gts/gts.h
:000000 100644 0000000... 4a37e58... A	gts/heap.c
:000000 100644 0000000... 80ac66a... A	gts/hsurface.c
:000000 100644 0000000... 5995a19... A	gts/iso.c
:000000 100644 0000000... 35fe2ba... A	gts/isotetra.c
:000000 100644 0000000... ec5d422... A	gts/kdtree.c
:000000 100644 0000000... 7ada15d... A	gts/matrix.c
:000000 100644 0000000... 393ba06... A	gts/misc.c
:000000 100644 0000000... 379f9f6... A	gts/named.c
:000000 100644 0000000... 5970e50... A	gts/object.c
:000000 100644 0000000... f0d76bf... A	gts/oocs.c
:000000 100644 0000000... 16dc0e1... A	gts/partition.c
:000000 100644 0000000... 6d1f619... A	gts/pgraph.c
:000000 100644 0000000... 42fce69... A	gts/point.c
:000000 100644 0000000... 7b7fcf2... A	gts/predicates.c
:000000 100644 0000000... 8b026ed... A	gts/predicates.h
:000000 100644 0000000... 6db3ae2... A	gts/psurface.c
:000000 100644 0000000... 293eb11... A	gts/refine.c
:000000 100644 0000000... 053b32f... A	gts/rounding.h
:000000 100644 0000000... 58a0540... A	gts/segment.c
:000000 100644 0000000... 8283e17... A	gts/split.c
:000000 100644 0000000... 7e98a9c... A	gts/stripe.c
:000000 100644 0000000... 34c5cbe... A	gts/surface.c
:000000 100644 0000000... 5213a51... A	gts/triangle.c
:000000 100644 0000000... c0ea778... A	gts/tribox3.c
:000000 100644 0000000... d312869... A	gts/vertex.c
:000000 100644 0000000... d772af9... A	gts/vopt.c
:100644 100644 e287ae7... 34c672d... M	src/Makefile.am
:100644 000000 8e051a6... 0000000... D	src/gts/.gitignore
:100644 000000 c697949... 0000000... D	src/gts/NOTES
:100644 000000 cec93e4... 0000000... D	src/gts/bbtree.c
:100644 000000 8b76d42... 0000000... D	src/gts/boolean.c
:100644 000000 2038ab5... 0000000... D	src/gts/cdt.c
:100644 000000 e1dc0fa... 0000000... D	src/gts/container.c
:100644 000000 70f6af2... 0000000... D	src/gts/curvature.c
:100644 000000 fde7d87... 0000000... D	src/gts/edge.c
:100644 000000 29f462d... 0000000... D	src/gts/eheap.c
:100644 000000 f6009f1... 0000000... D	src/gts/face.c
:100644 000000 8b3d2b6... 0000000... D	src/gts/fifo.c
:100644 000000 1566c95... 0000000... D	src/gts/graph.c
:100644 000000 59246d1... 0000000... D	src/gts/gts-private.h
:100644 000000 9397230... 0000000... D	src/gts/gts.h
:100644 000000 4a37e58... 0000000... D	src/gts/heap.c
:100644 000000 80ac66a... 0000000... D	src/gts/hsurface.c
:100644 000000 5995a19... 0000000... D	src/gts/iso.c
:100644 000000 35fe2ba... 0000000... D	src/gts/isotetra.c
:100644 000000 ec5d422... 0000000... D	src/gts/kdtree.c
:100644 000000 7ada15d... 0000000... D	src/gts/matrix.c
:100644 000000 393ba06... 0000000... D	src/gts/misc.c
:100644 000000 379f9f6... 0000000... D	src/gts/named.c
:100644 000000 5970e50... 0000000... D	src/gts/object.c
:100644 000000 f0d76bf... 0000000... D	src/gts/oocs.c
:100644 000000 16dc0e1... 0000000... D	src/gts/partition.c
:100644 000000 6d1f619... 0000000... D	src/gts/pgraph.c
:100644 000000 42fce69... 0000000... D	src/gts/point.c
:100644 000000 7b7fcf2... 0000000... D	src/gts/predicates.c
:100644 000000 8b026ed... 0000000... D	src/gts/predicates.h
:100644 000000 6db3ae2... 0000000... D	src/gts/psurface.c
:100644 000000 293eb11... 0000000... D	src/gts/refine.c
:100644 000000 053b32f... 0000000... D	src/gts/rounding.h
:100644 000000 58a0540... 0000000... D	src/gts/segment.c
:100644 000000 8283e17... 0000000... D	src/gts/split.c
:100644 000000 7e98a9c... 0000000... D	src/gts/stripe.c
:100644 000000 34c5cbe... 0000000... D	src/gts/surface.c
:100644 000000 5213a51... 0000000... D	src/gts/triangle.c
:100644 000000 c0ea778... 0000000... D	src/gts/tribox3.c
:100644 000000 d312869... 0000000... D	src/gts/vertex.c
:100644 000000 d772af9... 0000000... D	src/gts/vopt.c

=========
 Changes
=========

commit 8f3fcd5ba0c4f26aae49fca59fa128141388b265
Author: DJ Delorie <dj@xxxxxxxxxxx>
Commit: DJ Delorie <dj@xxxxxxxxxxx>

    Add top-level build changes to enable C++ compilation
    
    This patch moves GTS (gts.sourceforce.net) out of the src/
    tree and gives it its own Makefile, and changes src/Makefile.am
    so that C++ compilation is used if configure requests it.
    
    ./configure --enable-build-with-cxx
    ./configure --disable-build-with-cxx
    
    (the default is disable at the moment)
    
    Makefiles with these lines will use C++ if the user requests it:
    
    CC = @CC_OR_CXX@
    CFLAGS = @CC_OR_CXX_FLAGS@

diff --git a/Makefile.am b/Makefile.am
index f143862..41ca65a 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -3,7 +3,7 @@
 ##
 ## Top level automake file for PCB
 
-DIRS=		win32 intl src data lib newlib example tools tutorial README_FILES po tests
+DIRS=		win32 intl gts src data lib newlib example tools tutorial README_FILES po tests
 SUBDIRS=	${DIRS} @DOC@
 DIST_SUBDIRS=	${DIRS} doc
 
diff --git a/configure.ac b/configure.ac
index cf685a7..13e0e07 100644
--- a/configure.ac
+++ b/configure.ac
@@ -120,6 +120,7 @@ AC_DEFINE_UNQUOTED(PCB_PATH_DELIMETER,"$PCB_PATH_DELIMETER",[Search path separat
 
 dnl Checks for programs.
 AC_PROG_CC
+AC_PROG_CXX
 
 if test "x$WIN32" = "xyes" ; then
 	AC_CHECK_TOOL(WINDRES, windres, [no])
@@ -1036,6 +1037,27 @@ if test "x$GCC" = "xyes"; then
 	done
 fi
 
+CXXFLAGS="$CFLAGS"
+
+# See if we are building gcc with C++.
+AC_ARG_ENABLE(build-with-cxx,
+[  --enable-build-with-cxx build with C++ compiler instead of C compiler],
+ENABLE_BUILD_WITH_CXX=$enableval,
+ENABLE_BUILD_WITH_CXX=no)
+
+case "$ENABLE_BUILD_WITH_CXX" in
+  yes)
+    CC_OR_CXX="$CXX"
+    CC_OR_CXX_FLAGS="$CXXFLAGS"
+    ;;
+  no)
+    CC_OR_CXX="$CC"
+    CC_OR_CXX_FLAGS="$CFLAGS"
+    ;;
+esac
+AC_SUBST(CC_OR_CXX)
+AC_SUBST(CC_OR_CXX_FLAGS)
+
 # font filename
 FONTFILENAME=${FONTFILENAME:-"default_font"}
 AC_SUBST(FONTFILENAME)
@@ -1174,6 +1196,9 @@ AC_CONFIG_FILES(tests/Makefile)
 dnl win32 build scripts
 AC_CONFIG_FILES(win32/Makefile)
 
+dnl GTS 0.7.6 - http://gts.sourceforge.net/
+AC_CONFIG_FILES(gts/Makefile)
+
 AC_OUTPUT
 
 with_gui=`echo $with_gui`
@@ -1200,8 +1225,10 @@ AC_MSG_RESULT([
 
    Cross Compiling:          $cross_compiling
    CC:                       $CC
+   CXX:                      $CXX
    CPPFLAGS:                 $CPPFLAGS
    CFLAGS:                   $CFLAGS
+   CXXFLAGS:                 $CXXFLAGS
    LIBS:                     $LIBS
    PCB:                      $PCB
 
diff --git a/gts/.gitignore b/gts/.gitignore
new file mode 100644
index 0000000..8e051a6
--- /dev/null
+++ b/gts/.gitignore
@@ -0,0 +1,2 @@
+.dirstamp
+predicates_init.h
diff --git a/gts/Makefile.am b/gts/Makefile.am
new file mode 100644
index 0000000..ad7c938
--- /dev/null
+++ b/gts/Makefile.am
@@ -0,0 +1,48 @@
+## Process this file with automake to produce Makefile.in
+
+INCLUDES = -I$(srcdir) -DG_LOG_DOMAIN=\"Gts\"
+
+lib_LIBRARIES = libgts.a
+
+libgts_a_SOURCES = \
+	object.c \
+	point.c \
+	vertex.c \
+	segment.c \
+	edge.c \
+	triangle.c \
+	face.c \
+	kdtree.c \
+	bbtree.c \
+	misc.c \
+	gts.h \
+	gts-private.h \
+	predicates.c \
+	predicates.h \
+	rounding.h \
+	heap.c \
+	eheap.c \
+	fifo.c \
+	matrix.c \
+	surface.c \
+	stripe.c \
+	vopt.c \
+	refine.c \
+	iso.c \
+	isotetra.c \
+	split.c \
+	psurface.c \
+	hsurface.c \
+	cdt.c \
+	boolean.c \
+	named.c \
+	oocs.c \
+	container.c \
+	graph.c \
+	pgraph.c \
+	partition.c \
+	curvature.c \
+	tribox3.c
+
+include_HEADERS = \
+	gts.h
diff --git a/gts/NOTES b/gts/NOTES
new file mode 100644
index 0000000..c697949
--- /dev/null
+++ b/gts/NOTES
@@ -0,0 +1,3 @@
+- hsurface may create surfaces with duplicates edges and triangles (because of 
+ collapses of "empty triangles").
+- psurface however will not.
diff --git a/gts/bbtree.c b/gts/bbtree.c
new file mode 100644
index 0000000..cec93e4
--- /dev/null
+++ b/gts/bbtree.c
@@ -0,0 +1,1289 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <math.h>
+#include "gts.h"
+
+static void bbox_init (GtsBBox * bbox)
+{
+  bbox->bounded = NULL;
+}
+
+/**
+ * gts_bbox_class:
+ *
+ * Returns: the #GtsBBoxClass.
+ */
+GtsBBoxClass * gts_bbox_class (void)
+{
+  static GtsBBoxClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo bbox_info = {
+      "GtsBBox",
+      sizeof (GtsBBox),
+      sizeof (GtsBBoxClass),
+      (GtsObjectClassInitFunc) NULL,
+      (GtsObjectInitFunc) bbox_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (gts_object_class (), &bbox_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_bbox_set:
+ * @bbox: a #GtsBBox.
+ * @bounded: the object to be bounded.
+ * @x1: x-coordinate of the lower left corner.
+ * @y1: y-coordinate of the lower left corner.
+ * @z1: z-coordinate of the lower left corner.
+ * @x2: x-coordinate of the upper right corner.
+ * @y2: y-coordinate of the upper right corner.
+ * @z2: z-coordinate of the upper right corner.
+ *
+ * Sets fields of @bbox.
+ */
+void gts_bbox_set (GtsBBox * bbox,
+		   gpointer bounded,
+		   gdouble x1, gdouble y1, gdouble z1,
+		   gdouble x2, gdouble y2, gdouble z2)
+{
+  g_return_if_fail (bbox != NULL);
+  g_return_if_fail (x2 >= x1 && y2 >= y1 && z2 >= z1);
+
+  bbox->x1 = x1; bbox->y1 = y1; bbox->z1 = z1;
+  bbox->x2 = x2; bbox->y2 = y2; bbox->z2 = z2;
+  bbox->bounded = bounded;
+}
+
+/**
+ * gts_bbox_new:
+ * @klass: a #GtsBBoxClass.
+ * @bounded: the object to be bounded.
+ * @x1: x-coordinate of the lower left corner.
+ * @y1: y-coordinate of the lower left corner.
+ * @z1: z-coordinate of the lower left corner.
+ * @x2: x-coordinate of the upper right corner.
+ * @y2: y-coordinate of the upper right corner.
+ * @z2: z-coordinate of the upper right corner.
+ *
+ * Returns: a new #GtsBBox.
+ */
+GtsBBox * gts_bbox_new (GtsBBoxClass * klass,
+			gpointer bounded,
+			gdouble x1, gdouble y1, gdouble z1,
+			gdouble x2, gdouble y2, gdouble z2)
+{
+  GtsBBox * bbox;
+
+  g_return_val_if_fail (klass != NULL, NULL);
+
+  bbox = GTS_BBOX (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  gts_bbox_set (bbox, bounded, x1, y1, z1, x2, y2, z2);
+  return bbox;
+}
+
+/**
+ * gts_bbox_triangle:
+ * @klass: a #GtsBBoxClass.
+ * @t: a #GtsTriangle.
+ *
+ * Returns: a new #GtsBBox bounding box of @t.
+ */
+GtsBBox * gts_bbox_triangle (GtsBBoxClass * klass,
+			     GtsTriangle * t)
+{
+  GtsBBox * bbox;
+  GtsPoint * p;
+
+  g_return_val_if_fail (t != NULL, NULL);
+  g_return_val_if_fail (klass != NULL, NULL);
+
+  p = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
+  bbox = gts_bbox_new (klass, t, p->x, p->y, p->z, p->x, p->y, p->z);
+
+  p = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
+  if (p->x > bbox->x2) bbox->x2 = p->x;
+  if (p->x < bbox->x1) bbox->x1 = p->x;
+  if (p->y > bbox->y2) bbox->y2 = p->y;
+  if (p->y < bbox->y1) bbox->y1 = p->y;
+  if (p->z > bbox->z2) bbox->z2 = p->z;
+  if (p->z < bbox->z1) bbox->z1 = p->z;
+  p = GTS_POINT (gts_triangle_vertex (t));
+  if (p->x > bbox->x2) bbox->x2 = p->x;
+  if (p->x < bbox->x1) bbox->x1 = p->x;
+  if (p->y > bbox->y2) bbox->y2 = p->y;
+  if (p->y < bbox->y1) bbox->y1 = p->y;
+  if (p->z > bbox->z2) bbox->z2 = p->z;
+  if (p->z < bbox->z1) bbox->z1 = p->z;
+  
+  return bbox;
+}
+
+/**
+ * gts_bbox_segment:
+ * @klass: a #GtsBBoxClass.
+ * @s: a #GtsSegment.
+ * 
+ * Returns: a new #GtsBBox bounding box of @s.
+ */
+GtsBBox * gts_bbox_segment (GtsBBoxClass * klass, GtsSegment * s)
+{
+  GtsBBox * bbox;
+  GtsPoint * p1, * p2;
+
+  g_return_val_if_fail (s != NULL, NULL);
+  g_return_val_if_fail (klass != NULL, NULL);
+
+  bbox = gts_bbox_new (klass, s, 0., 0., 0., 0., 0., 0.);
+
+  p1 = GTS_POINT (s->v1); 
+  p2 = GTS_POINT (s->v2);
+  if (p1->x > p2->x) {
+    bbox->x2 = p1->x; bbox->x1 = p2->x;
+  }
+  else {
+    bbox->x1 = p1->x; bbox->x2 = p2->x;
+  }
+  if (p1->y > p2->y) {
+    bbox->y2 = p1->y; bbox->y1 = p2->y;
+  }
+  else {
+    bbox->y1 = p1->y; bbox->y2 = p2->y;
+  }
+  if (p1->z > p2->z) {
+    bbox->z2 = p1->z; bbox->z1 = p2->z;
+  }
+  else {
+    bbox->z1 = p1->z; bbox->z2 = p2->z;
+  }
+
+  return bbox;
+}
+
+static void bbox_foreach_vertex (GtsPoint * p, GtsBBox * bb)
+{
+  if (p->x < bb->x1) bb->x1 = p->x;
+  if (p->y < bb->y1) bb->y1 = p->y;
+  if (p->z < bb->z1) bb->z1 = p->z;
+  if (p->x > bb->x2) bb->x2 = p->x;
+  if (p->y > bb->y2) bb->y2 = p->y;
+  if (p->z > bb->z2) bb->z2 = p->z;
+}
+
+/**
+ * gts_bbox_surface:
+ * @klass: a #GtsBBoxClass.
+ * @surface: a #GtsSurface.
+ *
+ * Returns: a new #GtsBBox bounding box of @surface.
+ */
+GtsBBox * gts_bbox_surface (GtsBBoxClass * klass, GtsSurface * surface)
+{
+  GtsBBox * bbox;
+
+  g_return_val_if_fail (klass != NULL, NULL);
+  g_return_val_if_fail (surface != NULL, NULL);
+
+  bbox = gts_bbox_new (klass, surface, 0., 0., 0., 0., 0., 0.);
+  bbox->x1 = bbox->y1 = bbox->z1 = G_MAXDOUBLE;
+  bbox->x2 = bbox->y2 = bbox->z2 = -G_MAXDOUBLE;
+
+  gts_surface_foreach_vertex (surface, (GtsFunc) bbox_foreach_vertex, bbox);
+
+  return bbox;
+}
+
+/**
+ * gts_bbox_bboxes:
+ * @klass: a #GtsBBoxClass.
+ * @bboxes: a list of #GtsBBox.
+ * 
+ * Returns: a new #GtsBBox bounding box of all the bounding boxes in
+ * @bboxes.  
+ */
+GtsBBox * gts_bbox_bboxes (GtsBBoxClass * klass, GSList * bboxes)
+{
+  GtsBBox * bbox;
+  GtsBBox * bb;
+
+  g_return_val_if_fail (bboxes != NULL, NULL);
+  g_return_val_if_fail (klass != NULL, NULL);
+
+  bb = bboxes->data;
+  bbox = gts_bbox_new (klass, bboxes, 
+		       bb->x1, bb->y1, bb->z1, bb->x2, bb->y2, bb->z2);
+  bboxes = bboxes->next;
+  while (bboxes) {
+    bb = bboxes->data;
+    if (bb->x1 < bbox->x1) bbox->x1 = bb->x1;
+    if (bb->y1 < bbox->y1) bbox->y1 = bb->y1;
+    if (bb->z1 < bbox->z1) bbox->z1 = bb->z1;
+    if (bb->x2 > bbox->x2) bbox->x2 = bb->x2;
+    if (bb->y2 > bbox->y2) bbox->y2 = bb->y2;
+    if (bb->z2 > bbox->z2) bbox->z2 = bb->z2;
+    bboxes = bboxes->next;
+  }
+
+  return bbox;
+}
+
+/**
+ * gts_bbox_points:
+ * @klass: a #GtsBBoxClass.
+ * @points: a list of #GtsPoint.
+ *
+ * Returns: a new #GtsBBox bounding box of @points.
+ */
+GtsBBox * gts_bbox_points (GtsBBoxClass * klass, GSList * points)
+{
+  GtsPoint * p;
+  GtsBBox * bbox;
+  GSList * i;
+
+  if (points == NULL) 
+    return NULL;
+
+  p = points->data;  
+  bbox = gts_bbox_new (klass, points, p->x, p->y, p->z, p->x, p->y, p->z);
+
+  i = points->next;
+  while (i) {
+    p = i->data;
+    if (p->x > bbox->x2) 
+      bbox->x2 = p->x;
+    else if (p->x < bbox->x1) 
+      bbox->x1 = p->x;
+    if (p->y > bbox->y2) 
+      bbox->y2 = p->y;
+    else if (p->y < bbox->y1) 
+      bbox->y1 = p->y;
+    if (p->z > bbox->z2) 
+      bbox->z2 = p->z;
+    else if (p->z < bbox->z1) 
+      bbox->z1 = p->z;
+    i = i->next;
+  }
+  
+  return bbox;
+}
+
+/**
+ * gts_bboxes_are_overlapping:
+ * @bb1: a #GtsBBox.
+ * @bb2: a #GtsBBox.
+ *
+ * Returns: %TRUE if the bounding boxes @bb1 and @bb2 are overlapping
+ * (including just touching), %FALSE otherwise.
+ */
+gboolean gts_bboxes_are_overlapping (GtsBBox * bb1, GtsBBox * bb2)
+{
+  if (bb1 == bb2)
+    return TRUE;
+  if (bb1->x1 > bb2->x2)
+    return FALSE;
+  if (bb2->x1 > bb1->x2)
+    return FALSE;
+  if (bb1->y1 > bb2->y2)
+    return FALSE;
+  if (bb2->y1 > bb1->y2)
+    return FALSE;
+  if (bb1->z1 > bb2->z2)
+    return FALSE;
+  if (bb2->z1 > bb1->z2)
+    return FALSE;  
+  return TRUE;
+}
+
+#define bbox_volume(bb) (((bb)->x2 -\
+                          (bb)->x1)*\
+                         ((bb)->y2 -\
+                          (bb)->y1)*\
+                         ((bb)->z2 -\
+                          (bb)->z1))
+
+/**
+ * gts_bbox_diagonal2:
+ * @bb: a #GtsBBox.
+ *
+ * Returns: the squared length of the diagonal of @bb.
+ */
+gdouble gts_bbox_diagonal2 (GtsBBox * bb)
+{
+  gdouble x, y, z;
+
+  g_return_val_if_fail (bb != NULL, 0.);
+
+  x = bb->x2 - bb->x1;
+  y = bb->y2 - bb->y1;
+  z = bb->z2 - bb->z1;
+
+  return x*x + y*y + z*z;
+}
+
+/**
+ * gts_bbox_draw:
+ * @bb: a #GtsBBox.
+ * @fptr: a file pointer.
+ * 
+ * Writes in file @fptr an OOGL (Geomview) description of @bb.
+ */
+void gts_bbox_draw (GtsBBox * bb, FILE * fptr)
+{
+  g_return_if_fail (bb != NULL);
+
+  fprintf (fptr, "OFF 8 6 12\n");
+  fprintf (fptr, "%g %g %g\n",
+	   bb->x1, bb->y1, bb->z1);
+  fprintf (fptr, "%g %g %g\n",
+	   bb->x2, bb->y1, bb->z1);
+  fprintf (fptr, "%g %g %g\n",
+	   bb->x2, bb->y2, bb->z1);
+  fprintf (fptr, "%g %g %g\n",
+	   bb->x1, bb->y2, bb->z1);
+  fprintf (fptr, "%g %g %g\n",
+	   bb->x1, bb->y1, bb->z2);
+  fprintf (fptr, "%g %g %g\n",
+	   bb->x2, bb->y1, bb->z2);
+  fprintf (fptr, "%g %g %g\n",
+	   bb->x2, bb->y2, bb->z2);
+  fprintf (fptr, "%g %g %g\n",
+	   bb->x1, bb->y2, bb->z2);
+  fputs ("4 3 2 1 0\n"
+	 "4 4 5 6 7\n"
+	 "4 2 3 7 6\n"
+	 "4 0 1 5 4\n"
+	 "4 0 4 7 3\n"
+	 "4 1 2 6 5\n",
+	 fptr);
+}
+
+#define MINMAX(x1, x2, xmin, xmax) { if (x1 < x2) { xmin = x1; xmax = x2; }\
+                                     else { xmin = x2; xmax = x1; } }
+
+/**
+ * gts_bbox_point_distance2:
+ * @bb: a #GtsBBox.
+ * @p: a #GtsPoint.
+ * @min: a pointer on a gdouble.
+ * @max: a pointer on a gdouble.
+ * 
+ * Sets @min and @max to lower and upper bounds for the square of the
+ * Euclidean distance between the object contained in @bb and @p. For these
+ * bounds to make any sense the bounding box must be "tight" i.e. each of the
+ * 6 faces of the box must at least be touched by one point of the bounded
+ * object.
+ */
+void gts_bbox_point_distance2 (GtsBBox * bb, GtsPoint * p,
+			       gdouble * min, gdouble * max)
+{
+  gdouble x1, y1, z1, x2, y2, z2, x, y, z;
+  gdouble dmin, dmax, xd1, xd2, yd1, yd2, zd1, zd2;
+  gdouble mx, Mx, my, My, mz, Mz;
+    
+  g_return_if_fail (bb != NULL);
+  g_return_if_fail (p != NULL);
+  g_return_if_fail (min != NULL);
+  g_return_if_fail (max != NULL);
+
+  x1 = bb->x1; y1 = bb->y1; z1 = bb->z1; 
+  x2 = bb->x2; y2 = bb->y2; z2 = bb->z2;
+  x = p->x; y = p->y; z = p->z;
+
+  xd1 = (x1 - x)*(x1 - x);
+  xd2 = (x - x2)*(x - x2);
+  yd1 = (y1 - y)*(y1 - y);
+  yd2 = (y - y2)*(y - y2);
+  zd1 = (z1 - z)*(z1 - z);
+  zd2 = (z - z2)*(z - z2);
+  
+  dmin = x < x1 ? xd1 : x > x2 ? xd2 : 0.0;
+  dmin += y < y1 ? yd1 : y > y2 ? yd2 : 0.0;
+  dmin += z < z1 ? zd1 : z > z2 ? zd2 : 0.0;
+
+  MINMAX (xd1, xd2, mx, Mx);
+  MINMAX (yd1, yd2, my, My);
+  MINMAX (zd1, zd2, mz, Mz);
+  
+  dmax = mx + My + Mz;
+  dmax = MIN (dmax, Mx + my + Mz);
+  dmax = MIN (dmax, Mx + My + mz);
+  
+  *min = dmin;
+  *max = dmax;
+}
+
+/**
+ * gts_bbox_is_stabbed:
+ * @bb: a #GtsBBox.
+ * @p: a #GtsPoint.
+ *
+ * Returns: %TRUE if the ray starting at @p and ending at (+infty,
+ * @p->y, @p->z) intersects with @bb, %FALSE otherwise.
+ */
+gboolean gts_bbox_is_stabbed (GtsBBox * bb, GtsPoint * p)
+{
+  g_return_val_if_fail (bb != NULL, FALSE);
+  g_return_val_if_fail (p != NULL, FALSE);
+
+  if (p->x > bb->x2 ||
+      p->y < bb->y1 || p->y > bb->y2 ||
+      p->z < bb->z1 || p->z > bb->z2)
+    return FALSE;
+  return TRUE;
+}
+
+extern int triBoxOverlap (double boxcenter[3],
+			  double boxhalfsize[3],
+			  double triverts[3][3]);
+
+/**
+ * gts_bbox_overlaps_triangle:
+ * @bb: a #GtsBBox.
+ * @t: a #GtsTriangle.
+ *
+ * This is a wrapper around the fast overlap test of Tomas
+ * Akenine-Moller (http://www.cs.lth.se/home/Tomas_Akenine_Moller/).
+ *
+ * Returns: %TRUE if @bb overlaps with @t, %FALSE otherwise.
+ */
+gboolean gts_bbox_overlaps_triangle (GtsBBox * bb, GtsTriangle * t)
+{
+  double bc[3], bh[3], tv[3][3];
+  GtsPoint * p1, * p2, * p3;
+
+  g_return_val_if_fail (bb != NULL, FALSE);
+  g_return_val_if_fail (t != NULL, FALSE);
+
+  bc[0] = (bb->x2 + bb->x1)/2.;
+  bh[0] = (bb->x2 - bb->x1)/2.;
+  bc[1] = (bb->y2 + bb->y1)/2.;
+  bh[1] = (bb->y2 - bb->y1)/2.;
+  bc[2] = (bb->z2 + bb->z1)/2.;
+  bh[2] = (bb->z2 - bb->z1)/2.;
+  p1 = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
+  p2 = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
+  p3 = GTS_POINT (gts_triangle_vertex (t));
+  tv[0][0] = p1->x; tv[0][1] = p1->y; tv[0][2] = p1->z;
+  tv[1][0] = p2->x; tv[1][1] = p2->y; tv[1][2] = p2->z;
+  tv[2][0] = p3->x; tv[2][1] = p3->y; tv[2][2] = p3->z;
+
+  return triBoxOverlap (bc, bh, tv);
+}
+
+/**
+ * gts_bbox_overlaps_segment:
+ * @bb: a #GtsBBox.
+ * @s: a #GtsSegment.
+ *
+ * This functions uses gts_bbox_overlaps_triangle() with a degenerate
+ * triangle.
+ *
+ * Returns: %TRUE if @bb overlaps with @s, %FALSE otherwise.
+ */
+gboolean gts_bbox_overlaps_segment (GtsBBox * bb, GtsSegment * s)
+{
+  double bc[3], bh[3], tv[3][3];
+  GtsPoint * p1, * p2, * p3;
+
+  g_return_val_if_fail (bb != NULL, FALSE);
+  g_return_val_if_fail (s != NULL, FALSE);
+
+  bc[0] = (bb->x2 + bb->x1)/2.;
+  bh[0] = (bb->x2 - bb->x1)/2.;
+  bc[1] = (bb->y2 + bb->y1)/2.;
+  bh[1] = (bb->y2 - bb->y1)/2.;
+  bc[2] = (bb->z2 + bb->z1)/2.;
+  bh[2] = (bb->z2 - bb->z1)/2.;
+  p1 = GTS_POINT (s->v1);
+  p2 = GTS_POINT (s->v2);
+  p3 = p1;
+  tv[0][0] = p1->x; tv[0][1] = p1->y; tv[0][2] = p1->z;
+  tv[1][0] = p2->x; tv[1][1] = p2->y; tv[1][2] = p2->z;
+  tv[2][0] = p3->x; tv[2][1] = p3->y; tv[2][2] = p3->z;
+
+  return triBoxOverlap (bc, bh, tv);
+}
+
+/**
+ * gts_bb_tree_new:
+ * @bboxes: a list of #GtsBBox.
+ *
+ * Builds a new hierarchy of bounding boxes for @bboxes. At each
+ * level, the GNode->data field contains a #GtsBBox bounding box of
+ * all the children. The tree is binary and is built by repeatedly
+ * cutting in two approximately equal halves the bounding boxes at
+ * each level until a leaf node (i.e. a bounding box given in @bboxes)
+ * is reached. In order to minimize the depth of the tree, the cutting
+ * direction is always chosen as perpendicular to the longest
+ * dimension of the bounding box.
+ *
+ * Returns: a new hierarchy of bounding boxes.  
+ */
+GNode * gts_bb_tree_new (GSList * bboxes)
+{
+  GSList * i, * positive = NULL, * negative = NULL;
+  GNode * node;
+  GtsBBox * bbox;
+  guint dir, np = 0, nn = 0;
+  gdouble * p1, * p2;
+  gdouble cut;
+  
+  g_return_val_if_fail (bboxes != NULL, NULL);
+
+  if (bboxes->next == NULL) /* leaf node */
+    return g_node_new (bboxes->data);
+
+  bbox = gts_bbox_bboxes (gts_bbox_class (), bboxes);
+  node = g_node_new (bbox);
+
+  if (bbox->x2 - bbox->x1 > bbox->y2 - bbox->y1) {
+    if (bbox->z2 - bbox->z1 > bbox->x2 - bbox->x1)
+      dir = 2;
+    else
+      dir = 0;
+  }
+  else if (bbox->z2 - bbox->z1 > bbox->y2 - bbox->y1)
+    dir = 2;
+  else
+    dir = 1;
+
+  p1 = (gdouble *) &bbox->x1;
+  p2 = (gdouble *) &bbox->x2;
+  cut = (p1[dir] + p2[dir])/2.;
+  i = bboxes;
+  while (i) {
+    bbox = i->data; 
+    p1 = (gdouble *) &bbox->x1;
+    p2 = (gdouble *) &bbox->x2;
+    if ((p1[dir] + p2[dir])/2. > cut) {
+      positive = g_slist_prepend (positive, bbox);
+      np++;
+    }
+    else {
+      negative = g_slist_prepend (negative, bbox);
+      nn++;
+    }
+    i = i->next;
+  }
+  if (!positive) {
+    GSList * last = g_slist_nth (negative, (nn - 1)/2);
+    positive = last->next;
+    last->next = NULL;
+  }
+  else if (!negative) {
+    GSList * last = g_slist_nth (positive, (np - 1)/2);
+    negative = last->next;
+    last->next = NULL;
+  }
+  g_node_prepend (node, gts_bb_tree_new (positive));
+  g_slist_free (positive);
+  g_node_prepend (node, gts_bb_tree_new (negative));
+  g_slist_free (negative);
+  
+  return node;
+}
+
+static void prepend_triangle_bbox (GtsTriangle * t, GSList ** bboxes)
+{
+  *bboxes = g_slist_prepend (*bboxes, 
+			     gts_bbox_triangle (gts_bbox_class (), t));
+}
+
+/**
+ * gts_bb_tree_surface:
+ * @s: a #GtsSurface.
+ *
+ * Returns: a new hierarchy of bounding boxes bounding the faces of @s.
+ */
+GNode * gts_bb_tree_surface (GtsSurface * s)
+{
+  GSList * bboxes = NULL;
+  GNode * tree;
+
+  g_return_val_if_fail (s != NULL, NULL);
+
+  gts_surface_foreach_face (s, (GtsFunc) prepend_triangle_bbox, &bboxes);
+  tree = gts_bb_tree_new (bboxes);
+  g_slist_free (bboxes);
+
+  return tree;
+}
+
+/**
+ * gts_bb_tree_stabbed:
+ * @tree: a bounding box tree.
+ * @p: a #GtsPoint.
+ *
+ * Returns: a list of bounding boxes, leaves of @tree which are
+ * stabbed by the ray defined by @p (see gts_bbox_is_stabbed()).
+ */
+GSList * gts_bb_tree_stabbed (GNode * tree, GtsPoint * p)
+{
+  GSList * list = NULL;
+  GtsBBox * bb;
+  GNode * i;
+
+  g_return_val_if_fail (tree != NULL, NULL);
+  g_return_val_if_fail (p != NULL, NULL);
+
+  bb = tree->data;
+  if (!gts_bbox_is_stabbed (bb, p))
+    return NULL;
+  if (tree->children == NULL) /* leaf node */
+    return g_slist_prepend (NULL, bb);
+  i = tree->children;
+  while (i) {
+    list = g_slist_concat (list, gts_bb_tree_stabbed (i, p));
+    i = i->next;
+  }
+  return list;
+}
+
+/**
+ * gts_bb_tree_overlap:
+ * @tree: a bounding box tree.
+ * @bbox: a #GtsBBox.
+ *
+ * Returns: a list of bounding boxes, leaves of @tree which overlap @bbox.
+ */
+GSList * gts_bb_tree_overlap (GNode * tree, GtsBBox * bbox)
+{
+  GSList * list = NULL;
+  GtsBBox * bb;
+  GNode * i;
+
+  g_return_val_if_fail (tree != NULL, NULL);
+  g_return_val_if_fail (bbox != NULL, NULL);
+
+  bb = tree->data;
+  if (!gts_bboxes_are_overlapping (bbox, bb))
+    return NULL;
+  if (tree->children == NULL) /* leaf node */
+    return g_slist_prepend (NULL, bb);
+  i = tree->children;
+  while (i) {
+    list = g_slist_concat (list, gts_bb_tree_overlap (i, bbox));
+    i = i->next;
+  }
+  return list;
+}
+
+/**
+ * gts_bb_tree_is_overlapping:
+ * @tree: a bounding box tree.
+ * @bbox: a #GtsBBox.
+ *
+ * Returns: %TRUE if any leaf of @tree overlaps @bbox, %FALSE otherwise.
+ */
+gboolean gts_bb_tree_is_overlapping (GNode * tree, GtsBBox * bbox)
+{
+  GtsBBox * bb;
+  GNode * i;
+
+  g_return_val_if_fail (tree != NULL, FALSE);
+  g_return_val_if_fail (bbox != NULL, FALSE);
+
+  bb = tree->data;
+  if (!gts_bboxes_are_overlapping (bbox, bb))
+    return FALSE;
+  if (tree->children == NULL) /* leaf node */
+    return TRUE;
+  i = tree->children;
+  while (i) {
+    if (gts_bb_tree_is_overlapping (i, bbox))
+      return TRUE;
+    i = i->next;
+  }
+  return FALSE;
+}
+
+/**
+ * gts_bb_tree_traverse_overlapping:
+ * @tree1: a bounding box tree.
+ * @tree2: a bounding box tree.
+ * @func: a #GtsBBTreeTraverseFunc.
+ * @data: user data to be passed to @func.
+ *
+ * Calls @func for each overlapping pair of leaves of @tree1 and @tree2.
+ */
+void gts_bb_tree_traverse_overlapping (GNode * tree1, GNode * tree2,
+				       GtsBBTreeTraverseFunc func,
+				       gpointer data)
+{
+  GtsBBox * bb1, * bb2;
+
+  g_return_if_fail (tree1 != NULL && tree2 != NULL);
+
+  bb1 = tree1->data; bb2 = tree2->data;
+  if (!gts_bboxes_are_overlapping (bb1, bb2))
+    return;
+
+  if (tree1->children == NULL && tree2->children == NULL)
+    (*func) (tree1->data, tree2->data, data);
+  else if (tree2->children == NULL || 
+	   (tree1->children != NULL && 
+	    bbox_volume (bb1) > bbox_volume (bb2))) {
+    GNode * i = tree1->children;
+    while (i) {
+      gts_bb_tree_traverse_overlapping (i, tree2, func, data);
+      i = i->next;
+    }
+  }
+  else {
+    GNode * i = tree2->children;
+    while (i) {
+      gts_bb_tree_traverse_overlapping (tree1, i, func, data);
+      i = i->next;
+    }
+  }
+}
+
+/**
+ * gts_bb_tree_draw:
+ * @tree: a bounding box tree.
+ * @depth: a specified depth.
+ * @fptr: a file pointer.
+ *
+ * Write in @fptr an OOGL (Geomview) description of @tree for the
+ * depth specified by @depth.
+ */
+void gts_bb_tree_draw (GNode * tree, guint depth, FILE * fptr)
+{
+  guint d;
+
+  g_return_if_fail (tree != NULL);
+  g_return_if_fail (fptr != NULL);
+
+  d = g_node_depth (tree);
+
+  if (d == 1)
+    fprintf (fptr, "{ LIST");
+
+  if (d == depth)
+    gts_bbox_draw (tree->data, fptr);
+  else if (d < depth) {
+    GNode * i = tree->children;
+    while (i) {
+      gts_bb_tree_draw (i, depth, fptr);
+      i = i->next;
+    }
+  }
+
+  if (d == 1)
+    fprintf (fptr, "}\n");
+}
+
+static void bb_tree_free (GNode * tree, gboolean free_leaves)
+{
+  GNode * i;
+
+  g_return_if_fail (tree != NULL);
+
+  if (!free_leaves && tree->children == NULL) /* leaf node */
+    return;
+
+  gts_object_destroy (tree->data);
+
+  i = tree->children;
+  while (i) {
+    bb_tree_free (i, free_leaves);
+    i = i->next;
+  }
+}
+
+/**
+ * gts_bb_tree_destroy:
+ * @tree: a bounding box tree.
+ * @free_leaves: if %TRUE the bounding boxes given by the user are freed.
+ *
+ * Destroys all the bounding boxes created by @tree and destroys the
+ * tree itself. If @free_leaves is set to %TRUE, destroys boxes given
+ * by the user when creating the tree (i.e. leaves of the tree).  
+ */
+void gts_bb_tree_destroy (GNode * tree, gboolean free_leaves)
+{
+  g_return_if_fail (tree != NULL);
+  
+  bb_tree_free (tree, free_leaves);
+  g_node_destroy (tree);
+}
+
+static gdouble bb_tree_min_max (GNode * tree,
+				GtsPoint * p,
+				gdouble min_max,
+				GSList ** list)
+{
+  GNode * tree1, * tree2;
+  gdouble min1, max1, min2, max2;
+
+  if (tree->children == NULL) {
+    *list = g_slist_prepend (*list, tree->data);
+    return min_max;
+  }
+  tree1 = tree->children;
+  gts_bbox_point_distance2 (tree1->data, p, &min1, &max1);
+  if (max1 < min_max)
+    min_max = max1;
+
+  tree2 = tree1->next;
+  gts_bbox_point_distance2 (tree2->data, p, &min2, &max2);
+  if (max2 < min_max)
+    min_max = max2;
+
+  if (min1 < min2) {
+    if (min1 <= min_max) {
+      min_max = bb_tree_min_max (tree1, p, min_max, list);
+      if (min2 <= min_max)
+	min_max = bb_tree_min_max (tree2, p, min_max, list);
+    }
+  }
+  else {
+    if (min2 <= min_max) {
+      min_max = bb_tree_min_max (tree2, p, min_max, list);
+      if (min1 <= min_max)
+	min_max = bb_tree_min_max (tree1, p, min_max, list);
+    }
+  }
+
+  return min_max;
+}
+
+/**
+ * gts_bb_tree_point_closest_bboxes:
+ * @tree: a bounding box tree.
+ * @p: a #GtsPoint.
+ *
+ * Returns: a list of #GtsBBox. One of the bounding boxes is assured to contain
+ * the object of @tree closest to @p.
+ */
+GSList * gts_bb_tree_point_closest_bboxes (GNode * tree, 
+					   GtsPoint * p)
+{
+  gdouble min, min_max;
+  GSList * list = NULL, * i, * prev = NULL;
+
+  g_return_val_if_fail (tree != NULL, NULL);
+  g_return_val_if_fail (p != NULL, NULL);
+
+  gts_bbox_point_distance2 (tree->data, p, &min, &min_max);
+  min_max = bb_tree_min_max (tree, p, min_max, &list);
+
+  i = list;
+  while (i) {
+    GSList * next = i->next;
+    gdouble min, max;
+
+    gts_bbox_point_distance2 (i->data, p, &min, &max);
+
+    if (min > min_max) {
+      if (prev == NULL)
+	list = next;
+      else
+	prev->next = next;
+      g_slist_free_1 (i);
+    }
+    else
+      prev = i;
+    i = next;
+  }
+
+  return list;
+}
+
+/**
+ * gts_bb_tree_point_distance:
+ * @tree: a bounding box tree.
+ * @p: a #GtsPoint.
+ * @distance: a #GtsBBoxDistFunc.
+ * @bbox: if not %NULL is set to the bounding box containing the closest 
+ * object.
+ *
+ * Returns: the distance as evaluated by @distance between @p and the closest
+ * object in @tree.
+ */
+gdouble gts_bb_tree_point_distance (GNode * tree, 
+				    GtsPoint * p,
+				    GtsBBoxDistFunc distance,
+				    GtsBBox ** bbox)
+{
+  GSList * list, * i;
+  gdouble dmin = G_MAXDOUBLE;
+
+  g_return_val_if_fail (tree != NULL, dmin);
+  g_return_val_if_fail (p != NULL, dmin);
+  g_return_val_if_fail (distance != NULL, dmin);
+
+  i = list = gts_bb_tree_point_closest_bboxes (tree, p);
+  while (i) {
+    gdouble d = (*distance) (p, GTS_BBOX (i->data)->bounded);
+
+    if (fabs (d) < fabs (dmin)) {
+      dmin = d;
+      if (bbox)
+	*bbox = i->data;
+    }
+    i = i->next;
+  }
+  g_slist_free (list);
+
+  return dmin;
+}
+
+/**
+ * gts_bb_tree_point_closest:
+ * @tree: a bounding box tree.
+ * @p: a #GtsPoint.
+ * @closest: a #GtsBBoxClosestFunc.
+ * @distance: if not %NULL is set to the distance between @p and the 
+ * new #GtsPoint.
+ *
+ * Returns: a new #GtsPoint, closest point to @p and belonging to an object of
+ * @tree.
+ */
+GtsPoint * gts_bb_tree_point_closest (GNode * tree, 
+				      GtsPoint * p,
+				      GtsBBoxClosestFunc closest,
+				      gdouble * distance)
+{
+  GSList * list, * i;
+  gdouble dmin = G_MAXDOUBLE;
+  GtsPoint * np = NULL;
+
+  g_return_val_if_fail (tree != NULL, NULL);
+  g_return_val_if_fail (p != NULL, NULL);
+  g_return_val_if_fail (closest != NULL, NULL);
+
+  i = list = gts_bb_tree_point_closest_bboxes (tree, p);
+  while (i) {
+    GtsPoint * tp = (*closest) (p, GTS_BBOX (i->data)->bounded);
+    gdouble d = gts_point_distance2 (tp, p);
+
+    if (d < dmin) {
+      if (np)
+	gts_object_destroy (GTS_OBJECT (np));
+      np = tp;
+      dmin = d;
+    }
+    else
+      gts_object_destroy (GTS_OBJECT (tp));
+    i = i->next;
+  }
+  g_slist_free (list);
+
+  if (distance)
+    *distance = dmin;
+
+  return np;  
+}
+
+/**
+ * gts_bb_tree_triangle_distance:
+ * @tree: a bounding box tree.
+ * @t: a #GtsTriangle.
+ * @distance: a #GtsBBoxDistFunc.
+ * @delta: spatial scale of the sampling to be used.
+ * @range: a #GtsRange to be filled with the results.
+ * 
+ * Given a triangle @t, points are sampled regularly on its surface
+ * using @delta as increment. The distance from each of these points
+ * to the closest object of @tree is computed using @distance and the
+ * gts_bb_tree_point_distance() function. The fields of @range are
+ * filled with the number of points sampled, the minimum, average and
+ * maximum value and the standard deviation.  
+ */
+void gts_bb_tree_triangle_distance (GNode * tree,
+				    GtsTriangle * t,
+				    GtsBBoxDistFunc distance,
+				    gdouble delta,
+				    GtsRange * range)
+{
+  GtsPoint * p1, * p2, * p3, * p;
+  GtsVector p1p2, p1p3;
+  gdouble l1, t1, dt1;
+  guint i, n1;
+
+  g_return_if_fail (tree != NULL);
+  g_return_if_fail (t != NULL);
+  g_return_if_fail (distance != NULL);
+  g_return_if_fail (delta > 0.);
+  g_return_if_fail (range != NULL);
+
+  gts_triangle_vertices (t, 
+			 (GtsVertex **) &p1, 
+			 (GtsVertex **) &p2, 
+			 (GtsVertex **) &p3);
+
+  gts_vector_init (p1p2, p1, p2);
+  gts_vector_init (p1p3, p1, p3);
+  gts_range_init (range);
+  p = GTS_POINT (gts_object_new (GTS_OBJECT_CLASS (gts_point_class ())));
+
+  l1 = sqrt (gts_vector_scalar (p1p2, p1p2));
+  n1 = l1/delta + 1;
+  dt1 = 1.0/(gdouble) n1;
+  t1 = 0.0;
+  for (i = 0; i <= n1; i++, t1 += dt1) {
+    gdouble t2 = 1. - t1;
+    gdouble x = t2*p1p3[0];
+    gdouble y = t2*p1p3[1];
+    gdouble z = t2*p1p3[2];
+    gdouble l2 = sqrt (x*x + y*y + z*z);
+    guint j, n2 = (guint) (l2/delta + 1);
+    gdouble dt2 = t2/(gdouble) n2;
+
+    x = t2*p1->x + t1*p2->x;
+    y = t2*p1->y + t1*p2->y;
+    z = t2*p1->z + t1*p2->z;
+    
+    t2 = 0.0;
+    for (j = 0; j <= n2; j++, t2 += dt2) {
+      p->x = x + t2*p1p3[0];
+      p->y = y + t2*p1p3[1];
+      p->z = z + t2*p1p3[2];
+
+      gts_range_add_value (range,
+		    gts_bb_tree_point_distance (tree, p, distance, NULL));
+    }
+  }
+
+  gts_object_destroy (GTS_OBJECT (p));
+  gts_range_update (range);
+}
+
+/**
+ * gts_bb_tree_segment_distance:
+ * @tree: a bounding box tree.
+ * @s: a #GtsSegment.
+ * @distance: a #GtsBBoxDistFunc.
+ * @delta: spatial scale of the sampling to be used.
+ * @range: a #GtsRange to be filled with the results.
+ * 
+ * Given a segment @s, points are sampled regularly on its length
+ * using @delta as increment. The distance from each of these points
+ * to the closest object of @tree is computed using @distance and the
+ * gts_bb_tree_point_distance() function. The fields of @range are
+ * filled with the number of points sampled, the minimum, average and
+ * maximum value and the standard deviation.  
+ */
+void gts_bb_tree_segment_distance (GNode * tree,
+				   GtsSegment * s,
+				   gdouble (*distance) (GtsPoint *, 
+							gpointer),
+				   gdouble delta,
+				   GtsRange * range)
+{
+  GtsPoint * p1, * p2, * p;
+  GtsVector p1p2;
+  gdouble l, t, dt;
+  guint i, n;
+
+  g_return_if_fail (tree != NULL);
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (distance != NULL);
+  g_return_if_fail (delta > 0.);
+  g_return_if_fail (range != NULL);
+
+  p1 = GTS_POINT (s->v1);
+  p2 = GTS_POINT (s->v2);
+
+  gts_vector_init (p1p2, p1, p2);
+  gts_range_init (range);
+  p = GTS_POINT (gts_object_new (GTS_OBJECT_CLASS (gts_point_class())));
+
+  l = sqrt (gts_vector_scalar (p1p2, p1p2));
+  n = (guint) (l/delta + 1);
+  dt = 1.0/(gdouble) n;
+  t = 0.0;
+  for (i = 0; i <= n; i++, t += dt) {
+    p->x = p1->x + t*p1p2[0];
+    p->y = p1->y + t*p1p2[1];
+    p->z = p1->z + t*p1p2[2];
+    
+    gts_range_add_value (range,
+			 gts_bb_tree_point_distance (tree, p, distance, NULL));
+  }
+
+  gts_object_destroy (GTS_OBJECT (p));
+  gts_range_update (range);
+}
+
+static void surface_distance_foreach_triangle (GtsTriangle * t, 
+					       gpointer * data)
+{
+  gdouble * delta = data[1];
+  GtsRange * range = data[2];
+  gdouble * total_area = data[3], area;
+  GtsRange range_triangle;
+
+  gts_bb_tree_triangle_distance (data[0], t, data[4], *delta, &range_triangle);
+
+  if (range_triangle.min < range->min)
+    range->min = range_triangle.min;
+  if (range_triangle.max > range->max)
+    range->max = range_triangle.max;
+  range->n += range_triangle.n;
+
+  area = gts_triangle_area (t);
+  *total_area += area;
+  range->sum += area*range_triangle.mean;
+  range->sum2 += area*range_triangle.mean*range_triangle.mean;
+}
+
+/**
+ * gts_bb_tree_surface_distance:
+ * @tree: a bounding box tree.
+ * @s: a #GtsSurface.
+ * @distance: a #GtsBBoxDistFunc.
+ * @delta: a sampling increment defined as the percentage of the diagonal
+ * of the root bounding box of @tree.
+ * @range: a #GtsRange to be filled with the results.
+ *
+ * Calls gts_bb_tree_triangle_distance() for each face of @s. The
+ * fields of @range are filled with the minimum, maximum and average
+ * distance. The average distance is defined as the sum of the average
+ * distances for each triangle weighthed by their area and divided by
+ * the total area of the surface. The standard deviation is defined
+ * accordingly. The @n field of @range is filled with the number of
+ * sampled points used.  
+ */
+void gts_bb_tree_surface_distance (GNode * tree,
+				   GtsSurface * s,
+				   GtsBBoxDistFunc distance,
+				   gdouble delta,
+				   GtsRange * range)
+{
+  gpointer data[5];
+  gdouble total_area = 0.;
+
+  g_return_if_fail (tree != NULL);
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (delta > 0. && delta < 1.);
+  g_return_if_fail (range != NULL);
+
+  gts_range_init (range);
+  delta *= sqrt (gts_bbox_diagonal2 (tree->data));
+  data[0] = tree;
+  data[1] = &delta;
+  data[2] = range;
+  data[3] = &total_area;
+  data[4] = distance;
+
+  gts_surface_foreach_face (s, 
+			    (GtsFunc) surface_distance_foreach_triangle, 
+			    data);
+
+  if (total_area > 0.) {
+    if (range->sum2 - range->sum*range->sum/total_area >= 0.)
+      range->stddev = sqrt ((range->sum2 - range->sum*range->sum/total_area)
+			    /total_area);
+    else
+      range->stddev = 0.;
+    range->mean = range->sum/total_area;
+  }
+  else
+    range->min = range->max = range->mean = range->stddev = 0.;
+}
+
+static void surface_distance_foreach_boundary (GtsEdge * e,
+					       gpointer * data)
+{
+  gdouble * delta = data[1];
+  GtsRange * range = data[2];
+  gdouble * total_length = data[3], length;
+  GtsRange range_edge;
+
+  if (gts_edge_is_boundary (e, NULL)) {
+    GtsSegment * s =  GTS_SEGMENT (e);
+
+    gts_bb_tree_segment_distance (data[0], s, data[4], *delta, &range_edge);
+
+    if (range_edge.min < range->min)
+      range->min = range_edge.min;
+    if (range_edge.max > range->max)
+      range->max = range_edge.max;
+    range->n += range_edge.n;
+    
+    length = gts_point_distance (GTS_POINT (s->v1), GTS_POINT (s->v2));
+    *total_length += length;
+    range->sum += length*range_edge.mean;
+    range->sum2 += length*range_edge.mean*range_edge.mean;
+  }
+}
+
+/**
+ * gts_bb_tree_surface_boundary_distance:
+ * @tree: a bounding box tree.
+ * @s: a #GtsSurface.
+ * @distance: a #GtsBBoxDistFunc.
+ * @delta: a sampling increment defined as the percentage of the diagonal
+ * of the root bounding box of @tree.
+ * @range: a #GtsRange to be filled with the results.
+ *
+ * Calls gts_bb_tree_segment_distance() for each edge boundary of @s.
+ * The fields of @range are filled with the minimum, maximum and
+ * average distance. The average distance is defined as the sum of the
+ * average distances for each boundary edge weighthed by their length
+ * and divided by the total length of the boundaries. The standard
+ * deviation is defined accordingly. The @n field of @range is filled
+ * with the number of sampled points used.  
+ */
+void gts_bb_tree_surface_boundary_distance (GNode * tree,
+					    GtsSurface * s,
+					    gdouble (*distance) (GtsPoint *,
+								 gpointer),
+					    gdouble delta,
+					    GtsRange * range)
+{
+  gpointer data[5];
+  gdouble total_length = 0.;
+
+  g_return_if_fail (tree != NULL);
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (delta > 0. && delta < 1.);
+  g_return_if_fail (range != NULL);
+
+  gts_range_init (range);
+  delta *= sqrt (gts_bbox_diagonal2 (tree->data));
+  data[0] = tree;
+  data[1] = &delta;
+  data[2] = range;
+  data[3] = &total_length;
+  data[4] = distance;
+
+  gts_surface_foreach_edge (s, 
+			    (GtsFunc) surface_distance_foreach_boundary, 
+			    data);
+
+  if (total_length > 0.) {
+    if (range->sum2 - range->sum*range->sum/total_length >= 0.)
+      range->stddev = sqrt ((range->sum2 - 
+			     range->sum*range->sum/total_length)
+			    /total_length);
+    else
+      range->stddev = 0.;
+    range->mean = range->sum/total_length;
+  }
+  else
+    range->min = range->max = range->mean = range->stddev = 0.;
+}
diff --git a/gts/boolean.c b/gts/boolean.c
new file mode 100644
index 0000000..8b76d42
--- /dev/null
+++ b/gts/boolean.c
@@ -0,0 +1,2048 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999--2002 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <math.h>
+#include "gts.h"
+
+/*#define DEBUG*/
+/*#define DEBUG_BOOLEAN*/
+/*#define CHECK_ORIENTED*/
+
+#ifdef DEBUG
+#  include "gts-private.h"
+#endif /* DEBUG */
+
+static void surface_inter_destroy (GtsObject * object)
+{
+  GtsSurfaceInter * si = GTS_SURFACE_INTER (object);
+
+  gts_object_destroy (GTS_OBJECT (si->s1));
+  gts_object_destroy (GTS_OBJECT (si->s2));
+  g_slist_free (si->edges);
+
+  (* GTS_OBJECT_CLASS (gts_surface_inter_class ())->parent_class->destroy)
+    (object);
+}
+
+static void surface_inter_class_init (GtsObjectClass * klass)
+{
+  klass->destroy = surface_inter_destroy;
+}
+
+static void surface_inter_init (GtsSurfaceInter * si)
+{
+  si->s1 = si->s2 = NULL;
+  si->edges = NULL;
+}
+
+/**
+ * gts_surface_inter_class:
+ *
+ * Returns: the #GtsSurfaceInterClass.
+ */
+GtsSurfaceInterClass * gts_surface_inter_class (void)
+{
+  static GtsSurfaceInterClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo surface_inter_info = {
+      "GtsSurfaceInter",
+      sizeof (GtsSurfaceInter),
+      sizeof (GtsSurfaceInterClass),
+      (GtsObjectClassInitFunc) surface_inter_class_init,
+      (GtsObjectInitFunc) surface_inter_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (gts_object_class (), &surface_inter_info);
+  }
+
+  return klass;
+}
+
+/* EdgeInter: Header */
+
+typedef struct _EdgeInter         EdgeInter;
+
+struct _EdgeInter {
+  GtsEdge parent;
+
+  GtsTriangle * t1, * t2;
+};
+
+#define EDGE_INTER(obj)            GTS_OBJECT_CAST (obj,\
+					         EdgeInter,\
+					         edge_inter_class ())
+#define IS_EDGE_INTER(obj)         (gts_object_is_from_class (obj,\
+						 edge_inter_class ()))
+
+static GtsEdgeClass * edge_inter_class  (void);
+static EdgeInter * edge_inter_new    (GtsVertex * v1, GtsVertex * v2,
+				      GtsTriangle * t1, GtsTriangle * t2);
+
+/* EdgeInter: Object */
+
+static GtsEdgeClass * edge_inter_class (void)
+{
+  static GtsEdgeClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo edge_inter_info = {
+      "EdgeInter",
+      sizeof (EdgeInter),
+      sizeof (GtsEdgeClass),
+      (GtsObjectClassInitFunc) NULL,
+      (GtsObjectInitFunc) NULL,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_constraint_class ()),
+				  &edge_inter_info);
+  }
+
+  return klass;
+}
+
+static EdgeInter * edge_inter_new (GtsVertex * v1, GtsVertex * v2,
+				   GtsTriangle * t1, GtsTriangle * t2)
+{
+  EdgeInter * object;
+
+  object = EDGE_INTER (gts_edge_new (GTS_EDGE_CLASS (edge_inter_class ()), 
+				     v1, v2));
+  object->t1 = t1;
+  object->t2 = t2;
+
+  return object;
+}
+
+#ifdef DEBUG
+static void write_surface_graph (GtsSurface * s, FILE * fp)
+{
+  GSList * l = NULL;
+  GtsGraph * g;
+  static void add_to_list (gpointer data, GSList ** l) {
+    *l = g_slist_prepend (*l, data);
+  }
+
+  gts_surface_foreach_vertex (s, (GtsFunc) gts_object_reset_reserved, NULL);
+  gts_surface_foreach_edge (s, (GtsFunc) gts_object_reset_reserved, NULL);
+  gts_surface_foreach_edge (s, (GtsFunc) add_to_list, &l);
+  g = gts_segments_graph_new (gts_graph_class (), l);
+  gts_graph_write_dot (g, fp);
+  gts_object_destroy (GTS_OBJECT (g));
+  g_slist_free (l);
+}
+#endif /* DEBUG */
+
+static GtsPoint * segment_triangle_intersection (GtsSegment * s,
+						 GtsTriangle * t,
+						 GtsPointClass * klass)
+{
+  GtsPoint * A, * B, * C, * D, * E;
+  gint ABCE, ABCD, ADCE, ABDE, BCDE;
+  GtsEdge * AB, * BC, * CA;
+  gdouble a, b, c;
+
+  g_return_val_if_fail (s != NULL, NULL);
+  g_return_val_if_fail (t != NULL, NULL);
+  g_return_val_if_fail (klass != NULL, NULL);
+
+  gts_triangle_vertices_edges (t, NULL, 
+			       (GtsVertex **) &A, 
+			       (GtsVertex **) &B, 
+			       (GtsVertex **) &C, 
+			       &AB, &BC, &CA);
+  D = GTS_POINT (s->v1);
+  E = GTS_POINT (s->v2);
+
+  ABCE = gts_point_orientation_3d_sos (A, B, C, E);
+  ABCD = gts_point_orientation_3d_sos (A, B, C, D);
+  if (ABCE < 0 || ABCD > 0) {
+    GtsPoint * tmpp;
+    gint tmp;
+
+    tmpp = E; E = D; D = tmpp;
+    tmp = ABCE; ABCE = ABCD; ABCD = tmp;
+  }
+  if (ABCE < 0 || ABCD > 0)
+    return NULL;
+  ADCE = gts_point_orientation_3d_sos (A, D, C, E);
+  if (ADCE < 0)
+    return NULL;
+  ABDE = gts_point_orientation_3d_sos (A, B, D, E);
+  if (ABDE < 0)
+    return NULL;
+  BCDE = gts_point_orientation_3d_sos (B, C, D, E);
+  if (BCDE < 0)
+    return NULL;
+  a = gts_point_orientation_3d (A, B, C, E);
+  b = gts_point_orientation_3d (A, B, C, D);
+  if (a != b) {
+    c = a/(a - b);
+    return gts_point_new (klass,
+			  E->x + c*(D->x - E->x),
+			  E->y + c*(D->y - E->y),
+			  E->z + c*(D->z - E->z));
+  }
+  /* D and E are contained within ABC */
+#ifdef DEBUG
+  fprintf (stderr, 
+	   "segment: %p:%s triangle: %p:%s intersection\n"
+	   "D and E contained in ABC\n",
+	   s, GTS_NEDGE (s)->name, t, GTS_NFACE (t)->name);
+#endif /* DEBUG */  
+  g_assert (a == 0.); 
+  return gts_point_new (klass,
+			(E->x + D->x)/2.,
+			(E->y + D->y)/2.,
+			(E->z + D->z)/2.);
+}
+
+static gint triangle_triangle_orientation (GtsPoint * p1, 
+					   GtsPoint * p2, GtsPoint * p3,
+					   GtsPoint * p4, GtsPoint * p5,
+					   GtsPoint * p6)
+{
+  gint o4 = 0, o5 = 0, o6 = 0;
+
+  if (p4 != p1 && p4 != p2 && p4 != p3)
+    o4 = gts_point_orientation_3d_sos (p1, p2, p3, p4);
+  if (p5 != p1 && p5 != p2 && p5 != p3)
+    o5 = gts_point_orientation_3d_sos (p1, p2, p3, p5);
+  if (o4*o5 < 0)
+    return 0;
+  if (p6 != p1 && p6 != p2 && p6 != p3)
+    o6 = gts_point_orientation_3d_sos (p1, p2, p3, p6);
+  if (o4*o6 < 0 || o5*o6 < 0)
+    return 0;
+  if (o4) return o4;
+  if (o5) return o5;
+  g_assert (o6);
+  return o6;
+}
+
+static gint triangle_point_orientation (GtsTriangle * t1, 
+					GtsTriangle * t2,
+					gint o1,
+					GtsPoint * p)
+{
+  GtsPoint * p1 = GTS_POINT (GTS_SEGMENT (t1->e1)->v1);
+  GtsPoint * p2 = GTS_POINT (GTS_SEGMENT (t1->e1)->v2);
+  GtsPoint * p3 = GTS_POINT (gts_triangle_vertex (t1));
+  GtsPoint * p4 = GTS_POINT (GTS_SEGMENT (t2->e1)->v1);
+  GtsPoint * p5 = GTS_POINT (GTS_SEGMENT (t2->e1)->v2);
+  GtsPoint * p6 = GTS_POINT (gts_triangle_vertex (t2));
+  gint o = triangle_triangle_orientation (p1, p2, p3, p4, p5, p6);
+
+  if (o != 0)
+    return o;
+  o = triangle_triangle_orientation (p4, p5, p6, p1, p2, p3);
+  if (o != 0) {
+    gint o2 = gts_point_orientation_3d_sos (p4, p5, p6, p);
+
+    return - o*o1*o2;
+  }
+  return 0;
+}
+
+static void add_edge_inter (GtsEdge * e,
+			    GtsTriangle * t,
+			    GtsVertex * v)
+{
+  GtsVertex * ev1 = GTS_SEGMENT (e)->v1, * ev2 = GTS_SEGMENT (e)->v2;
+  GList * i = GTS_OBJECT (e)->reserved;
+
+  GTS_OBJECT (v)->reserved = t;
+  if (i == NULL) {
+    GTS_OBJECT (e)->reserved = g_list_prepend (NULL, v);
+#ifdef DEBUG
+    fprintf (stderr, "add_edge_inter: inserting %p (%p,%p)\n", v, e, t);
+#endif /* DEBUG */
+  }
+  else {
+    GtsPoint * p1 = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
+    GtsPoint * p2 = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
+    GtsPoint * p3 = GTS_POINT (gts_triangle_vertex (t));
+    gint o1, oref = gts_point_orientation_3d_sos (p1, p2, p3, GTS_POINT (ev1));
+    
+    o1 = oref;
+    while (i) {
+      gint o2 = triangle_point_orientation (t, GTS_OBJECT (i->data)->reserved,
+					    oref, GTS_POINT (ev1));
+
+      if (o2 == 0) {
+#ifdef DEBUG
+	g_warning ("add_edge_inter: safe sign evaluation failed\n");
+#endif /* DEBUG */
+	o2 = gts_point_orientation_3d_sos (p1, p2, p3, i->data);
+      }
+
+      if (o1*o2 < 0)
+	break;
+      ev1 = i->data;
+      o1 = o2;
+      i = i->next;
+    }
+    if (i != NULL) {
+      GList * n = g_list_prepend (NULL, v);
+
+      ev2 = i->data;
+      n->next = i;
+      n->prev = i->prev;
+      i->prev = n;
+      if (n->prev == NULL)
+	GTS_OBJECT (e)->reserved = n;
+      else
+	n->prev->next = n;
+    }
+    else {
+      g_assert (o1*gts_point_orientation_3d_sos (p1, p2, p3, GTS_POINT (ev2))
+		< 0);
+      GTS_OBJECT (e)->reserved = g_list_append (GTS_OBJECT (e)->reserved, v);
+    }
+#ifdef DEBUG
+    fprintf (stderr, 
+	     "add_edge_inter: inserting %p (%p,%p) between %p and %p\n", 
+	     v, e, t, ev1, ev2);
+    i = GTS_OBJECT (e)->reserved;
+    while (i) {
+      fprintf (stderr, " %p", i->data);
+      i = i->next;
+    }
+    fprintf (stderr, "\n");
+#endif /* DEBUG */
+  }
+}
+
+static GtsVertex * intersects (GtsEdge * e,
+			       GtsTriangle * t,
+			       GtsSurface * s)
+{
+  GList * i = GTS_OBJECT (e)->reserved;
+  GtsVertex * v;
+
+  while (i) {
+    if (GTS_OBJECT (i->data)->reserved == t)
+      return i->data;
+    i = i->next;
+  }
+
+  v = GTS_VERTEX (segment_triangle_intersection (GTS_SEGMENT (e), t, 
+				    GTS_POINT_CLASS (s->vertex_class)));
+  if (v != NULL) {
+#ifdef DEBUG
+    if (GTS_IS_NVERTEX (v) && GTS_IS_NEDGE (e) && GTS_IS_NFACE (t) &&
+	GTS_NVERTEX (v)->name[0] == '\0')
+      g_snprintf (GTS_NVERTEX (v)->name, GTS_NAME_LENGTH, "%s|%s",
+		  GTS_NEDGE (e)->name, GTS_NFACE (t)->name);
+#endif /* DEBUG */
+    if (s->vertex_class->intersection_attributes)
+      (*s->vertex_class->intersection_attributes)
+	(v, GTS_OBJECT (e), GTS_OBJECT (t));
+    add_edge_inter (e, t, v);
+  }
+  return v;
+}
+
+/* see figure misc/orientation.fig */
+static gint intersection_orientation (GtsTriangle * t1, 
+				      GtsEdge * e,
+				      GtsTriangle * t2)
+{
+  GtsVertex * v1, * v2, * v3;
+  GtsEdge * e2, * e3;
+  GtsVertex * v4, * v5, * v6;
+
+  gts_triangle_vertices_edges (t1, e, &v1, &v2, &v3, &e, &e2, &e3);
+  gts_triangle_vertices (t2, &v4, &v5, &v6);
+
+  return gts_point_orientation_3d_sos (GTS_POINT (v4), 
+				       GTS_POINT (v5), 
+				       GTS_POINT (v6),
+				       GTS_POINT (v2));
+}
+
+#define UPDATE_ORIENTATION if (o > 0) { vi2 = v; e2 = e; } else { vi2 = vi1;\
+                                                                  e2 = e1;\
+                                                                  vi1 = v;\
+                                                                  e1 = e; }
+
+static void intersect_edges (GtsBBox * bb1, GtsBBox * bb2,
+			     GtsSurfaceInter * si)
+{
+  GtsSurface * s1 = GTS_OBJECT (si->s1)->reserved;
+  GtsTriangle * t1 = GTS_TRIANGLE (bb1->bounded);
+  GtsTriangle * t2 = GTS_TRIANGLE (bb2->bounded);
+  GtsVertex * v, * vi1 = NULL, * vi2 = NULL;
+  GtsEdge * e1 = NULL, * e2 = NULL, * e;
+
+  vi1 = intersects (t2->e1, t1, s1);
+  e1 = t2->e1;
+  v = intersects (t2->e2, t1, s1);
+  e = t2->e2;
+  if (!vi1) {
+    vi1 = v;
+    e1 = e;
+  }
+  else if (v) {
+    gint o = intersection_orientation (t2, t2->e2, t1);
+    UPDATE_ORIENTATION;
+  }
+  if (!vi2) {
+    v = intersects (t2->e3, t1, s1);
+    e = t2->e3;
+    if (!vi1) {
+      vi1 = v;
+      e1 = e;
+    }
+    else if (v) {
+      gint o = intersection_orientation (t2, t2->e3, t1);
+      UPDATE_ORIENTATION;
+    }
+  }
+  if (!vi2) {
+    v = intersects (t1->e1, t2, s1);
+    e = t1->e1;
+    if (!vi1) {
+      vi1 = v;
+      e1 = e;
+    }
+    else if (v) {
+      gint o = - intersection_orientation (t1, t1->e1, t2);
+      UPDATE_ORIENTATION;
+    }
+  }
+  if (!vi2) {
+    v = intersects (t1->e2, t2, s1);
+    e = t1->e2;
+    if (!vi1) {
+      vi1 = v;
+      e1 = e;
+    }
+    else if (v) {
+      gint o = - intersection_orientation (t1, t1->e2, t2);
+      UPDATE_ORIENTATION;
+    }
+  }
+  if (!vi2) {
+    v = intersects (t1->e3, t2, s1);
+    e = t1->e3;
+    if (!vi1) {
+      vi1 = v;
+      e1 = e;
+    }
+    else if (v) {
+      gint o = - intersection_orientation (t1, t1->e3, t2);
+      UPDATE_ORIENTATION;
+    }
+  }
+
+  g_assert ((!vi1 && !vi2) || (vi1 && vi2));
+  if (vi1) {
+    GtsEdge * e = GTS_EDGE (edge_inter_new (vi1, vi2, t1, t2));
+
+#ifdef DEBUG
+    fprintf (stderr, "creating constraint %p: %p->%p: %p/%p\n", 
+	     e, vi1, vi2, t1, t2);
+#endif /* DEBUG */
+    gts_surface_add_face (si->s1, GTS_FACE (t1));
+    gts_surface_add_face (si->s2, GTS_FACE (t2));
+    si->edges = g_slist_prepend (si->edges, e);
+    GTS_OBJECT (t1)->reserved = g_slist_prepend (GTS_OBJECT (t1)->reserved, e);
+    GTS_OBJECT (t2)->reserved = g_slist_prepend (GTS_OBJECT (t2)->reserved, e);
+  }
+}
+
+static GtsSurfaceInter * surface_inter_new (GtsSurfaceInterClass * klass,
+					    GtsSurface * s1,
+					    GtsSurface * s2,
+					    GNode * faces_tree1,
+					    GNode * faces_tree2)
+{
+  GtsSurfaceInter * si;
+
+  si = GTS_SURFACE_INTER (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  si->s1 = gts_surface_new (gts_surface_class (),
+			    s1->face_class,
+			    s1->edge_class,
+			    s1->vertex_class);
+  GTS_OBJECT (si->s1)->reserved = s1;
+  si->s2 = gts_surface_new (gts_surface_class (),
+			    s2->face_class,
+			    s2->edge_class,
+			    s2->vertex_class);
+  GTS_OBJECT (si->s2)->reserved = s2;
+  gts_bb_tree_traverse_overlapping (faces_tree1, faces_tree2,
+				    (GtsBBTreeTraverseFunc) intersect_edges, 
+				    si);
+
+  return si;
+}
+
+static void free_slist (GtsObject * o)
+{
+  g_slist_free (o->reserved);
+  o->reserved = NULL;
+}
+
+static void free_glist (GtsObject * o)
+{
+  g_list_foreach (o->reserved, (GFunc) gts_object_reset_reserved, NULL);
+  g_list_free (o->reserved);
+  o->reserved = NULL;
+}
+
+/**
+ * gts_surface_intersection:
+ * @s1: a #GtsSurface.
+ * @s2: a #GtsSurface.
+ * @faces_tree1: a bounding box tree (see gts_bb_tree_new()) for
+ * the faces of @s1.
+ * @faces_tree2: a bounding box tree for the faces of @s2.
+ *
+ * Returns: a list of #GtsEdge defining the curve intersection of the
+ * two surfaces.
+ */
+GSList * gts_surface_intersection (GtsSurface * s1,
+				   GtsSurface * s2,
+				   GNode * faces_tree1,
+				   GNode * faces_tree2)
+{
+  GtsSurfaceInter * si;
+  GSList * inter;
+
+  g_return_val_if_fail (s1 != NULL, NULL);
+  g_return_val_if_fail (s2 != NULL, NULL);
+  g_return_val_if_fail (faces_tree1 != NULL, NULL);
+  g_return_val_if_fail (faces_tree2 != NULL, NULL);
+
+  si = surface_inter_new (gts_surface_inter_class (),
+			  s1, s2, faces_tree1, faces_tree2);
+
+  gts_surface_foreach_face (si->s1, (GtsFunc) free_slist, NULL);
+  gts_surface_foreach_face (si->s2, (GtsFunc) free_slist, NULL);
+  gts_surface_foreach_edge (si->s1, (GtsFunc) free_glist, NULL);
+  gts_surface_foreach_edge (si->s2, (GtsFunc) free_glist, NULL);
+  inter = si->edges;
+  si->edges = NULL;
+  gts_object_destroy (GTS_OBJECT (si));
+
+  return inter;  
+}
+
+typedef enum {
+  INTERIOR = 1 << (GTS_USER_FLAG),
+  RELEVANT = 1 << (GTS_USER_FLAG + 1)
+} CurveFlag;
+
+#define IS_SET(s, f) ((GTS_OBJECT_FLAGS (s) & (f)) != 0)
+#define SET(s, f)   (GTS_OBJECT_FLAGS (s) |= (f))
+#define UNSET(s, f) (GTS_OBJECT_FLAGS (s) &= ~(f))
+#define NEXT(s)  (GTS_OBJECT (s)->reserved)
+
+#ifdef DEBUG
+static void print_segment (GtsSegment * s)
+{
+  fprintf (stderr, "%p: %s->%s ", s,
+	   GTS_NVERTEX (s->v1)->name,
+	   GTS_NVERTEX (s->v2)->name);
+  if (NEXT (s)) {
+    GtsSegment * next = NEXT (s);
+
+    fprintf (stderr, "next %p: %s->%s\n", next,
+	     GTS_NVERTEX (next->v1)->name,
+	     GTS_NVERTEX (next->v2)->name);
+  }
+  else
+    fprintf (stderr, "next NULL\n");
+}
+
+static void write_nodes (GSList * i, GHashTable * hash, guint * nn,
+			 FILE * fp)
+{
+  while (i) {
+    GtsSegment * s = i->data;
+
+    if (!g_hash_table_lookup (hash, s->v1)) {
+      fprintf (fp, "  %u [ label = \"%p\" ];\n", *nn, s->v1);
+      g_hash_table_insert (hash, s->v1, GUINT_TO_POINTER ((*nn)++));
+    }
+    if (!g_hash_table_lookup (hash, s->v2)) {
+      fprintf (fp, "  %u [ label = \"%p\" ];\n", *nn, s->v2);
+      g_hash_table_insert (hash, s->v2, GUINT_TO_POINTER ((*nn)++));
+    }
+    i = i->next;
+  }
+}
+
+static void write_edges (GSList * i, GHashTable * hash, 
+			 GtsSurface * surface,
+			 FILE * fp)
+{
+  while (i) {
+    GtsSegment * s = i->data;
+
+    fprintf (fp, "  %u -> %u [ label = \"%p:%d\" ];\n",
+	     GPOINTER_TO_UINT (g_hash_table_lookup (hash, s->v1)),
+	     GPOINTER_TO_UINT (g_hash_table_lookup (hash, s->v2)),
+	     s,
+	     gts_edge_face_number (GTS_EDGE (s), surface));
+    i = i->next;
+  }
+}
+
+static void write_graph (GSList * boundary, GSList * interior,
+			 GtsSurface * surface,
+			 FILE * fp)
+{
+  GHashTable * hash = g_hash_table_new (NULL, NULL);
+  guint nn = 1;
+  
+  fprintf (fp, "digraph oriented_curve {\n");
+  write_nodes (boundary, hash, &nn, fp);
+  write_nodes (interior, hash, &nn, fp);
+  write_edges (boundary, hash, surface, fp);
+  fprintf (fp, "  edge [ color = red ];\n");
+  write_edges (interior, hash, surface, fp);
+  fprintf (fp, "}\n");
+  g_hash_table_destroy (hash);
+}
+
+static void write_graph1 (GtsSegment * start, GSList * i,
+			  GtsSurface * surface,
+			  FILE * fp)
+{
+  GSList * boundary = NULL, * interior = NULL;
+  GtsSegment * s = start;
+
+  do {
+    boundary = g_slist_prepend (boundary, s);
+    s = NEXT (s);
+  } while (s != start);
+  while (i) {
+    if (IS_SET (i->data, INTERIOR))
+      interior = g_slist_prepend (interior, i->data);
+    i = i->next;
+  }
+  write_graph (boundary, interior, surface, fp);
+  g_slist_free (boundary);
+  g_slist_free (interior);
+}
+
+static void print_loop (GtsSegment * start, FILE * fp)
+{
+  GtsSegment * s = start;
+
+  do {
+    fprintf (fp, "  %p: %p:%s -> %p:%s\n",
+	     s, 
+	     s->v1, GTS_NVERTEX (s->v1)->name, 
+	     s->v2, GTS_NVERTEX (s->v2)->name);
+    s = NEXT (s);
+  } while (s != start && s != NULL);
+}
+
+static void draw_vector (GtsPoint * p1, GtsPoint * p2, FILE * fp)
+{
+  gdouble x = p2->x - p1->x;
+  gdouble y = p2->y - p1->y;
+  gdouble z = p2->z - p1->z;
+
+  fprintf (fp, "VECT 1 3 0 3 0 %g %g %g %g %g %g %g %g %g\n",
+	   p1->x + x - (x - y/2.)/5.,
+	   p1->y + y - (x/2. + y)/5.,
+	   p1->z + z - (x/2. + z)/5.,
+	   p1->x + x,
+	   p1->y + y,
+	   p1->z + z,
+	   p1->x + x - (x + y/2.)/5.,
+	   p1->y + y + (x/2. - y)/5.,
+	   p1->z + z + (x/2. - z)/5.);
+  fprintf (fp, "VECT 1 2 0 2 0 %g %g %g %g %g %g\n",
+	   p1->x, p1->y, p1->z,
+	   p1->x + x,
+	   p1->y + y,
+	   p1->z + z);
+}
+
+static void draw_vector1 (GtsPoint * p1, GtsPoint * p2, GtsPoint * o,
+			  FILE * fp)
+{
+  gdouble x1 = o->x + 0.9*(p1->x - o->x);
+  gdouble y1 = o->y + 0.9*(p1->y - o->y);
+  gdouble z1 = o->z + 0.9*(p1->z - o->z);
+  gdouble x2 = o->x + 0.9*(p2->x - o->x);
+  gdouble y2 = o->y + 0.9*(p2->y - o->y);
+  gdouble z2 = o->z + 0.9*(p2->z - o->z);
+  gdouble x = x2 - x1;
+  gdouble y = y2 - y1;
+  gdouble z = z2 - z1;
+
+  fprintf (fp, "VECT 1 3 0 3 0 %g %g %g %g %g %g %g %g %g\n",
+	   x1 + x - (x - y/2.)/5.,
+	   y1 + y - (x/2. + y)/5.,
+	   z1 + z - (x/2. + z)/5.,
+	   x1 + x,
+	   y1 + y,
+	   z1 + z,
+	   x1 + x - (x + y/2.)/5.,
+	   y1 + y + (x/2. - y)/5.,
+	   z1 + z + (x/2. - z)/5.);
+  fprintf (fp, "VECT 1 2 0 2 0 %g %g %g %g %g %g\n",
+	   x1, y1, z1,
+	   x1 + x,
+	   y1 + y,
+	   z1 + z);
+}
+
+static void write_segments (GSList * boundary, GSList * interior,
+			    FILE * fp)
+{
+  GSList * i = boundary;
+
+  fprintf (fp, "LIST {\n");
+  while (i) {
+    GSList * inext = i->next;
+    GtsSegment * s = i->data;
+    GtsSegment * next = inext ? inext->data : boundary->data;
+    GtsVertex * v1, * v2;
+
+    if (s->v1 != next->v1 && s->v1 != next->v2) {
+      v1 = s->v1;
+      v2 = s->v2;
+    }
+    else {
+      v1 = s->v2;
+      v2 = s->v1;
+    }
+    draw_vector (GTS_POINT (v1), GTS_POINT (v2), fp);
+    i = inext;
+  }
+  i = interior;
+  while (i) {
+    GtsSegment * s = i->data;
+
+    draw_vector (GTS_POINT (s->v1), GTS_POINT (s->v2), fp);
+    i = i->next;
+  }
+  fprintf (fp, "}\n");
+}
+
+static void write_loops (GSList * i, FILE * fp)
+{
+  guint nl = 0;
+
+  while (i) {
+    GtsSegment * start = i->data, * s;
+    GtsPoint os;
+    guint n = 0;
+
+    fprintf (fp, "(geometry \"loop%d\" = LIST {\n", nl++);    
+
+    os.x = os.y = os.z = 0.;
+    s = start;
+    do {
+      GtsSegment * next = NEXT (s);
+      GtsPoint * p;
+      
+      if (s->v1 != next->v1 && s->v1 != next->v2)
+	p = GTS_POINT (s->v1);
+       else
+	 p = GTS_POINT (s->v2);
+      os.x += p->x; os.y += p->y; os.z += p->z; n++;
+      s = next;
+     } while (s != start);
+    os.x /= n; os.y /= n; os.z /= n;
+    
+    s = start;
+    do {
+      GtsSegment * next = NEXT (s);
+      
+      if (s->v1 != next->v1 && s->v1 != next->v2)
+	draw_vector1 (GTS_POINT (s->v1), GTS_POINT (s->v2), &os, fp);
+      else
+	 draw_vector1 (GTS_POINT (s->v2), GTS_POINT (s->v1), &os, fp);
+      s = next;
+    } while (s != start);
+    
+    fprintf (fp, "})\n");
+
+    i = i->next;
+  }
+}
+
+#define NAME(v) (GTS_IS_NVERTEX (v) ? GTS_NVERTEX (v)->name : "")
+#endif /* DEBUG */
+
+static GtsSegment * prev_flag (GtsSegment * s, CurveFlag flag)
+{
+  GSList * i = s->v1->segments;
+
+  while (i) {
+    if (i->data != s && IS_SET (i->data, flag))
+      return i->data;
+    i = i->next;
+  }
+  return NULL;
+}
+
+static GtsSegment * next_flag (GtsSegment * s, CurveFlag flag)
+{
+  GSList * i = s->v2->segments;
+
+  while (i) {
+    if (i->data != s && IS_SET (i->data, flag))
+      return i->data;
+    i = i->next;
+  }
+  return NULL;
+}
+
+static GtsSegment * next_interior (GtsVertex * v)
+{
+  GSList * i = v->segments;
+
+  while (i) {
+    GtsSegment * s = i->data;
+
+    if (s->v1 == v && IS_SET (s, INTERIOR))
+      return s;
+    i = i->next;
+  }
+  return NULL;
+}
+
+static GtsSegment * prev_interior (GtsVertex * v)
+{
+  GSList * i = v->segments;
+
+  while (i) {
+    GtsSegment * s = i->data;
+
+    if (s->v2 == v && IS_SET (s, INTERIOR))
+      return s;
+    i = i->next;
+  }
+  return NULL;
+}
+
+static GtsSegment * reverse (GtsSegment * start,
+			     gboolean interior,
+			     gboolean * isloop)
+{
+  GtsSegment * s = start, * prev = NULL, * rprev = NULL;
+  GtsSegment * rstart = NULL, * rstart1 = NULL;
+
+  do {
+    GtsSegment * rs;
+
+    g_assert (IS_EDGE_INTER (s));
+    rs = GTS_SEGMENT (edge_inter_new (s->v2, s->v1,
+				      EDGE_INTER (s)->t1, EDGE_INTER (s)->t2));
+
+    if (rstart == NULL)
+      rstart = rs;
+    else if (rstart1 == NULL)
+      rstart1 = rs;
+    if (interior)
+      SET (rs, INTERIOR);
+    NEXT (rs) = rprev;
+    rprev = rs;
+    prev = s;
+    s = NEXT (s);
+  } while (s != NULL && s != start);
+  if (s == start) {
+    NEXT (rstart) = rprev;
+    *isloop = TRUE;
+  }
+  else {
+    NEXT (rstart) = start;
+    NEXT (prev) = rprev;
+    *isloop = FALSE;
+  }    
+  return rstart1;
+}
+
+static GSList * interior_loops (GSList * interior)
+{
+  GSList * i = interior;
+  GSList * loops = NULL;
+
+  i = interior;
+  while (i) {
+    GtsSegment * s = i->data;
+
+    if (IS_SET (s, RELEVANT)) {
+      GtsSegment * start = s, * end;
+
+      do {
+	GtsSegment * next = next_flag (s, INTERIOR);
+
+	UNSET (s, RELEVANT);
+	end = s; 
+	s = NEXT (s) = next;
+      } while (s != NULL && s != start);
+
+      if (s == start)
+	loops = g_slist_prepend (loops, start);
+      else {
+	GtsSegment * next, * prev;
+	gboolean isloop;
+
+	s = prev_flag (start, INTERIOR);
+	while (s) {
+	  UNSET (s, RELEVANT);
+	  NEXT (s) = start;
+	  start = s;
+	  s = prev_flag (s, INTERIOR);
+	}
+	next = next_flag (end, RELEVANT);
+	prev = prev_flag (start, RELEVANT);
+	if (prev != NULL)
+	  SET (start->v1, INTERIOR);
+	if (next != NULL)
+	  SET (end->v2, INTERIOR);
+	if (next == NULL && prev == NULL)
+	  loops = g_slist_prepend (loops, start);
+	else
+	  reverse (start, TRUE, &isloop);
+      }
+    }
+    i = i->next;
+  }
+  return loops;
+}
+
+#define ORIENTATION(p1,p2,p3,o) (gts_point_orientation_3d (p1, p2, o, p3))
+#define ORIENTATION_SOS(p1,p2,p3,o) (gts_point_orientation_3d_sos (p1, p2, o, p3))
+
+#define ORIENTED_VERTICES(s,next,w1,w2) {\
+  if ((s)->v1 == (next)->v1 || (s)->v1 == (next)->v2) {\
+    w1 = (s)->v2;\
+    w2 = (s)->v1;\
+  }\
+  else {\
+    w1 = (s)->v1;\
+    w2 = (s)->v2;\
+  }\
+}
+
+#if 0
+static GtsSegment * segment_intersects (GtsPoint * p1, GtsPoint * p2,
+					GSList * i,
+					GtsPoint * o)
+{
+  while (i) {
+    GtsSegment * s = i->data;
+    GtsPoint * p3 = GTS_POINT (s->v1);
+    GtsPoint * p4 = GTS_POINT (s->v2);
+
+    if (p3 != p1 && p3 != p2 && p4 != p1 && p4 != p2) {
+      gdouble o1 = ORIENTATION (p3, p4, p1, o);
+      gdouble o2 = ORIENTATION (p3, p4, p2, o);
+
+      if ((o1 < 0. && o2 > 0.) || (o1 > 0. && o2 < 0.)) {
+	o1 = ORIENTATION (p1, p2, p3, o);
+	o2 = ORIENTATION (p1, p2, p4, o);
+
+	if ((o1 <= 0. && o2 >= 0.) || (o1 >= 0. && o2 <= 0.))
+	  return s;
+      }
+    }
+    i = i->next;
+  }
+  return NULL;
+}
+#else
+static GtsSegment * segment_intersects (GtsPoint * p1, GtsPoint * p2,
+					GSList * i,
+					GtsPoint * o)
+{
+  while (i) {
+    GtsSegment * s = i->data;
+    GtsPoint * p3 = GTS_POINT (s->v1);
+    GtsPoint * p4 = GTS_POINT (s->v2);
+
+    if (p3 != p1 && p3 != p2 && p4 != p1 && p4 != p2) {
+      gint o1 = ORIENTATION_SOS (p3, p4, p1, o);
+      gint o2 = ORIENTATION_SOS (p3, p4, p2, o);
+
+      if (o1*o2 < 0) {
+	o1 = ORIENTATION_SOS (p1, p2, p3, o);
+	o2 = ORIENTATION_SOS (p1, p2, p4, o);
+
+	if (o1*o2 < 0)
+	  return s;
+      }
+    }
+    i = i->next;
+  }
+  return NULL;
+}
+#endif
+
+static gboolean is_inside_wedge (GtsSegment * s1, GtsSegment * s2,
+				 GtsPoint * p, GtsPoint * o)
+{
+  GtsVertex * v1, * v2, * v3;
+
+  ORIENTED_VERTICES (s1, s2, v1, v2);
+  v3 = s2->v1 != v2 ? s2->v1 : s2->v2;
+
+  if (ORIENTATION (GTS_POINT (v1), GTS_POINT (v2), 
+		   GTS_POINT (v3), o) >= 0.) {
+    if (ORIENTATION (GTS_POINT (v1), GTS_POINT (v2), p, o) <= 0. ||
+	ORIENTATION (GTS_POINT (v2), GTS_POINT (v3), p, o) <= 0.)
+      return FALSE;
+  }
+  else if (ORIENTATION (GTS_POINT (v1), GTS_POINT (v2), p, o) <= 0. &&
+	   ORIENTATION (GTS_POINT (v2), GTS_POINT (v3), p, o) <= 0.)
+    return FALSE;
+  return TRUE;
+}
+
+static GtsSegment * connection (GtsPoint * p, 
+				GSList * interior,
+				GSList * bloops,
+				GtsPoint * o)
+{
+  while (bloops) {
+    GtsSegment * start = bloops->data, * s = start;
+
+    do {
+      GtsSegment * next = NEXT (s);
+      GtsVertex * v2 = s->v1 == next->v1 || s->v1 == next->v2 ? s->v1 : s->v2;
+
+      if (is_inside_wedge (s, next, p, o) &&
+	  !segment_intersects (p, GTS_POINT (v2), interior, o))
+	return s;
+      s = next;
+    } while (s != start);
+    bloops = bloops->next;
+  }
+  return NULL;
+}
+
+static gdouble loop_orientation (GtsSegment * start,
+				 GtsPoint * p, GtsPoint * o)
+{
+  GtsSegment * s = start;
+  gdouble or = 0.;
+
+  do {
+    GtsSegment * next = NEXT (s);
+    GtsVertex * v1, * v2;
+
+    ORIENTED_VERTICES (s, next, v1, v2);
+    or += ORIENTATION (p, GTS_POINT (v1), GTS_POINT (v2), o);
+    s = next;
+  } while (s != start);
+
+#ifdef DEBUG
+  fprintf (stderr, "loop orientation: %g\n", or);
+#endif /* DEBUG */
+
+  return or;
+}
+
+static void connect_interior_loop (GtsSegment * start,
+				   GSList ** interior,
+				   GSList ** bloops,
+				   GtsSurface * surface,
+				   GtsPoint * o)
+{
+  GtsSegment * s = start, * c = NULL, * next, * s1, * rs1, * rs;
+  GtsVertex * v, * cv;
+  gboolean isloop;
+
+  do {
+    if (!(c = connection (GTS_POINT (s->v2), *interior, *bloops, o)))
+      s = NEXT (s);
+  } while (s != start && !c);
+  g_assert (c);
+  next = NEXT (c);
+  v = c->v1 == next->v1 || c->v1 == next->v2 ? c->v1 : c->v2;
+  cv = s->v2;
+#ifdef DEBUG
+  fprintf (stderr, "connecting %p:%s with %p:%s\n", 
+	   cv, NAME (cv), v, NAME (v));
+  fprintf (stderr, "  c: %p: %p:%s %p:%s\n", c, 
+	   c->v1, NAME (c->v1),
+	   c->v2, NAME (c->v2));
+  fprintf (stderr, "  next: %p: %p:%s %p:%s\n", next,
+	   next->v1, NAME (next->v1),
+	   next->v2, NAME (next->v2));
+#endif /* DEBUG */
+  rs = reverse (s, FALSE, &isloop);
+  if (isloop) {
+    if (loop_orientation (rs, GTS_POINT (v), o) < 0.) {
+      GtsSegment * tmp = s;
+      s = rs;
+      rs = tmp;
+    }
+    *bloops = g_slist_prepend (*bloops, rs);
+  }
+  s1 = GTS_SEGMENT (gts_edge_new (surface->edge_class, v, cv));
+  rs1 = GTS_SEGMENT (gts_edge_new (surface->edge_class, cv, v));
+  NEXT (c) = s1;
+  NEXT (rs1) = next;
+  *interior = g_slist_prepend (*interior, s1);
+  NEXT (s1) = NEXT (s);
+  NEXT (s) = rs1;
+}
+
+static GSList * boundary_loops (GSList * boundary)
+{
+  GSList * i = boundary;  
+  GtsSegment * start = i->data;
+  GSList * loops = NULL;
+
+  while (i) {
+    GtsSegment * s = i->data;
+    GSList * inext = i->next;
+    GtsSegment * next = inext ? inext->data : start;
+    GtsVertex * v = s->v1 == next->v1 || s->v1 == next->v2 ? s->v1 : s->v2;
+
+    if (IS_SET (v, INTERIOR)) {
+      GtsSegment * intprev = prev_interior (v);
+
+      NEXT (intprev) = next;
+      NEXT (s) = next_interior (v);
+      UNSET (v, INTERIOR);
+    }
+    else
+      NEXT (s) = next;
+    i = inext;
+  }
+
+  i = boundary;
+  while (i) {
+    start = i->data;
+    
+    if (IS_SET (start, RELEVANT)) {
+      GtsSegment * s = start;
+
+      do {
+	UNSET (s, RELEVANT);
+	UNSET (s, INTERIOR);
+	s = NEXT (s);
+      } while (s != start);
+      loops = g_slist_prepend (loops, start);
+    }
+    i = i->next;
+  }
+
+  return loops;
+}
+
+typedef struct _Ear    Ear;
+
+struct _Ear {
+  GtsVertex * v1, * v2, * v3;
+  GtsSegment * s1, * s2, * s3;
+};
+
+static gboolean point_in_wedge (GtsPoint * p1, GtsPoint * p2, GtsPoint * p3,
+				GtsPoint * p, gboolean closed, GtsPoint * o)
+{
+  gdouble o1;
+
+  if (p == p2 || p == p3)
+    return FALSE;
+  o1 = ORIENTATION (p1, p2, p, o);
+  if ((closed && o1 < 0.) || (!closed && o1 <= 0.)) return FALSE;
+  o1 = ORIENTATION (p3, p1, p, o);
+  if ((closed && o1 < 0.) || (!closed && o1 <= 0.)) return FALSE;
+  return TRUE;
+}
+
+#if 0
+static gboolean segment_intersects1 (GtsPoint * p1, GtsPoint * p2, 
+				     GtsPoint * p3, GtsPoint * p4,
+				     gboolean closed, GtsPoint * o)
+{
+  gdouble o1 = ORIENTATION (p3, p4, p1, o);
+  gdouble o2 = ORIENTATION (p3, p4, p2, o);
+  gdouble o3, o4;
+
+  if ((closed && ((o1 > 0. && o2 > 0.) || (o1 < 0. && o2 < 0.))) ||
+      (!closed && ((o1 >= 0. && o2 >= 0.) || (o1 <= 0. && o2 <= 0.))))
+    return FALSE;
+  o3 = ORIENTATION (p1, p2, p3, o);
+  o4 = ORIENTATION (p1, p2, p4, o);
+  if ((o3 > 0. && o4 > 0.) || (o3 < 0. && o4 < 0.))
+    return FALSE;
+  if (closed) return TRUE;
+  if ((o3 == 0. && o4 > 0.) || (o4 == 0. && o3 > 0.))
+    return TRUE;
+  return FALSE;
+}
+#else
+static gboolean segment_intersects1 (GtsPoint * p1, GtsPoint * p2, 
+				     GtsPoint * p3, GtsPoint * p4,
+				     gboolean closed, GtsPoint * o)
+{
+  gint o1, o2;
+
+  o1 = ORIENTATION_SOS (p3, p4, p1, o);
+  o2 = ORIENTATION_SOS (p3, p4, p2, o);
+  if (o1*o2 > 0)
+    return FALSE;
+  o1 = ORIENTATION_SOS (p1, p2, p3, o);
+  o2 = ORIENTATION_SOS (p1, p2, p4, o);
+  if (o1*o2 > 0)
+    return FALSE;
+  return TRUE;
+}
+#endif
+
+static GtsSegment * triangle_intersects_segments (GtsPoint * p1,
+						  GtsPoint * p2,
+						  GtsPoint * p3,
+						  gboolean closed,
+						  GtsSegment * start,
+						  GtsPoint * o)
+{
+  GtsSegment * s = start;
+
+  do {
+    GtsPoint * p4 = GTS_POINT (s->v1);
+    GtsPoint * p5 = GTS_POINT (s->v2);
+
+    if (p4 == p1) {
+      if (point_in_wedge (p1, p2, p3, p5, closed, o))
+	return s;
+    }
+    else if (p4 == p2) {
+      if (point_in_wedge (p2, p3, p1, p5, closed, o))
+	return s;
+    }
+    else if (p4 == p3) {
+      if (point_in_wedge (p3, p1, p2, p5, closed, o))
+	return s;
+    }
+    else if (p5 == p1) {
+      if (point_in_wedge (p1, p2, p3, p4, closed, o))
+	return s;
+    }
+    else if (p5 == p2) {
+      if (point_in_wedge (p2, p3, p1, p4, closed, o))
+	return s;
+    }
+    else if (p5 == p3) {
+      if (point_in_wedge (p3, p1, p2, p4, closed, o))
+	return s;
+    }
+    else if (segment_intersects1 (p1, p2, p4, p5, closed, o) ||
+	     segment_intersects1 (p2, p3, p4, p5, closed, o) ||
+	     segment_intersects1 (p3, p1, p4, p5, closed, o))
+      return s;
+    s = NEXT (s);
+  } while (s != start);
+  return NULL;
+}
+
+static gboolean new_ear (GtsSegment * s, 
+			 Ear * e, 
+			 GtsSegment * start,
+			 guint sloppy,
+			 GtsPoint * o)
+{
+  gdouble or;
+
+  e->s1 = s;
+  e->s2 = NEXT (s);
+
+  g_return_val_if_fail (e->s2, FALSE);
+  g_return_val_if_fail (e->s2 != e->s1, FALSE);
+
+  ORIENTED_VERTICES (e->s1, e->s2, e->v1, e->v2);
+  e->v3 = e->s2->v1 != e->v2 ? e->s2->v1 : e->s2->v2;
+  if (e->v3 == e->v1)
+    return FALSE;
+  e->s3 = NEXT (e->s2);
+  if (gts_segment_connect (e->s3, e->v1, e->v3)) {
+    if (NEXT (e->s3) != e->s1)
+      return FALSE;
+  }
+  else if (gts_vertices_are_connected (e->v1, e->v3))
+    return FALSE;
+  else
+    e->s3 = NULL;
+  or = ORIENTATION (GTS_POINT (e->v1), GTS_POINT (e->v2), GTS_POINT (e->v3),o);
+  switch (sloppy) {
+  case 0: 
+    if (or <= 0. ||
+	triangle_intersects_segments (GTS_POINT (e->v1), GTS_POINT (e->v2),
+				      GTS_POINT (e->v3), TRUE, start, o))
+      return FALSE;
+    break;
+  case 1:
+    if (or < 0. || 
+	(or > 0. && 
+	 triangle_intersects_segments (GTS_POINT (e->v1), GTS_POINT (e->v2),
+				       GTS_POINT (e->v3), FALSE, start, o)))
+      return FALSE;
+    break;
+  case 2:
+    if ((or > 0. && 
+	 triangle_intersects_segments (GTS_POINT (e->v1), GTS_POINT (e->v2),
+				       GTS_POINT (e->v3), FALSE, start, o)) ||
+	(or < 0. && 
+	 triangle_intersects_segments (GTS_POINT (e->v2), GTS_POINT (e->v1),
+				       GTS_POINT (e->v3), FALSE, start, o)))
+      return FALSE;
+    break;
+  case 3:
+    if (or < 0.)
+      return FALSE;
+    break;
+  }
+#ifdef DEBUG
+  if (or <= 0.)
+    fprintf (stderr, "or: %g\n", or);
+#endif /* DEBUG */
+  g_assert (or > -1e-6);
+  return TRUE;
+}
+
+static void triangulate_loop (GtsSegment * start,
+			      GtsSurface * surface,
+			      GtsPoint * o)
+{
+  GtsSegment * prev = start, * s;
+  guint sloppy = 0;
+#ifdef DEBUG
+  guint nt = 0;
+#endif /* DEBUG */
+
+  s = NEXT (start);
+  while (NEXT (s) != s) {
+    GtsSegment * next = NEXT (s);
+    Ear e;
+
+#ifdef DEBUG
+    fprintf (stderr, "prev: %p s: %p next: %p\n", prev, s, next);
+#endif /* DEBUG */
+  
+    if (!new_ear (s, &e, start, sloppy, o)) {
+      if (s == start) {
+	sloppy++;
+#ifdef DEBUG
+	fprintf (stderr, "sloppy: %u\n", sloppy);
+#endif /* DEBUG */
+      }
+      prev = s;
+      s = next;
+    }
+    else {
+      GtsFace * f;
+
+      if (!GTS_IS_EDGE (e.s3))
+	e.s3 = GTS_SEGMENT (gts_edge_new (surface->edge_class, e.v1, e.v3));
+      f = gts_face_new (surface->face_class, 
+			GTS_EDGE (e.s1), GTS_EDGE (e.s2), GTS_EDGE (e.s3));
+      gts_surface_add_face (surface, f);
+      UNSET (e.s1, RELEVANT);
+      UNSET (e.s1, INTERIOR);
+      UNSET (e.s2, RELEVANT);
+      UNSET (e.s2, INTERIOR);
+      NEXT (prev) = e.s3;
+      NEXT (e.s3) = NEXT (e.s2);
+      NEXT (e.s1) = NEXT (e.s2) = NULL;
+      start = prev;
+      s = NEXT (prev);
+      sloppy = 0;
+#ifdef DEBUG
+      {
+	gchar name[80];
+	FILE * fp;
+	
+	fprintf (stderr, " t.%u: (%p:%s,%p:%s,%p:%s)\n",
+		 nt, 
+		 e.v1, NAME (e.v1),
+		 e.v2, NAME (e.v2),
+		 e.v3, NAME (e.v3));
+	sprintf (name, "/tmp/t.%u", nt++);
+	fp = fopen (name, "wt");
+	//	gts_surface_write (surface, fp);
+	gts_write_triangle (GTS_TRIANGLE (f), NULL, fp);
+	//	  write_graph1 (start, interior, surface, fp);
+	fclose (fp);
+	print_loop (start, stderr);
+      }
+#endif /* DEBUG */
+    }
+  }
+  UNSET (s, RELEVANT);
+  UNSET (s, INTERIOR);
+  NEXT (s) = NULL;
+}
+
+#ifdef CHECK_ORIENTED
+static void check_object (GtsObject * o)
+{
+  g_assert (o->reserved == NULL);
+  g_assert (o->flags == 0);  
+}
+
+static void check_boundary (GtsEdge * e, GtsSurface * s)
+{
+  check_object (GTS_OBJECT (e));
+  check_object (GTS_OBJECT (GTS_SEGMENT (e)->v1));
+  check_object (GTS_OBJECT (GTS_SEGMENT (e)->v2));
+  g_assert (gts_edge_face_number (e, s) == 1);
+}
+
+static void check_interior (GtsEdge * e, GtsSurface * s)
+{
+  guint n;
+  check_object (GTS_OBJECT (e));
+  check_object (GTS_OBJECT (GTS_SEGMENT (e)->v1));
+  check_object (GTS_OBJECT (GTS_SEGMENT (e)->v2));
+
+  n = gts_edge_face_number (e, s);
+#ifdef DEBUG
+  if (n != 2)
+    gts_surface_print_stats (s, stderr);
+#endif /* DEBUG */
+  g_assert (n == 2);
+}
+
+static void check_boundary_interior_triangulation (GSList * boundary,
+						   GSList * interior,
+						   GtsSurface * surface)
+{
+  g_slist_foreach (boundary, (GFunc) check_boundary, surface);
+  g_slist_foreach (interior, (GFunc) check_interior, surface);
+}
+#endif /*ifdef CHECK_ORIENTED */
+
+static void merge_duplicate (GtsEdge * e)
+{
+  GtsEdge * dup = gts_edge_is_duplicate (e);
+
+  g_assert (dup);
+  gts_edge_replace (dup, e);
+  gts_object_destroy (GTS_OBJECT (dup));
+}
+
+static void triangulate_boundary_interior (GSList * boundary, 
+					   GSList * interior,
+					   GtsSurface * s,
+					   GtsPoint * o)
+{
+  GSList * iloops, * bloops, * i;
+
+  i = boundary;
+  while (i) {
+    SET (i->data, RELEVANT);
+    i = i->next;
+  }
+  i = interior;
+  while (i) {
+    SET (i->data, RELEVANT);
+    SET (i->data, INTERIOR);
+    i = i->next;
+  }
+
+  iloops = interior_loops (interior);
+  bloops = boundary_loops (boundary);
+
+  i = iloops;
+  while (i) {
+#ifdef DEBUG
+    fprintf (stderr, "--- interior loop ---\n");
+    print_loop (i->data, stderr);
+#endif /* DEBUG */
+    connect_interior_loop (i->data, &interior, &bloops, s, o);
+    i = i->next;
+  }
+  
+#ifdef DEBUG
+ {
+   FILE * fp = fopen ("/tmp/bloops", "w");
+   write_loops (bloops, fp);
+   fclose (fp);
+ }
+#endif /* DEBUG */
+
+  i = bloops;
+  while (i) {
+#ifdef DEBUG
+    fprintf (stderr, "--- boundary loop ---\n");
+    print_loop (i->data, stderr);
+#endif /* DEBUG */
+    triangulate_loop (i->data, s, o);
+    i = i->next;
+  }
+  
+  g_slist_foreach (interior, (GFunc) merge_duplicate, NULL);
+  g_slist_free (iloops);
+  g_slist_free (bloops);
+
+#ifdef CHECK_ORIENTED
+  check_boundary_interior_triangulation (boundary, interior, s);
+#endif /* CHECK_ORIENTED */
+}
+
+static void create_edges (GtsSegment * s, GtsSurface * surface)
+{
+  if (GTS_OBJECT (s)->reserved) {
+    GList * i = GTS_OBJECT (s)->reserved;
+    GtsVertex * v1 = i->data;
+
+    GTS_OBJECT (s)->reserved = g_list_prepend (i, 
+		      gts_edge_new (surface->edge_class, s->v1, v1));
+    while (i) {
+      GList * next = i->next;
+      GtsVertex * v2 = next ? next->data : s->v2;
+
+      GTS_OBJECT (i->data)->reserved = NULL;
+      i->data = gts_edge_new (surface->edge_class, v1, v2);
+      v1 = v2;
+      i = next;
+    }
+  }
+}
+
+static void add_boundary (GtsSegment * s, GtsSegment * next, 
+			  GSList ** boundary)
+{
+  if (GTS_OBJECT (s)->reserved == NULL)
+    *boundary = g_slist_prepend (*boundary, s);
+  else {
+    if (s->v2 == next->v2 || s->v2 == next->v1) {
+      GList * i = g_list_last (GTS_OBJECT (s)->reserved);
+
+      while (i) {
+	*boundary = g_slist_prepend (*boundary, i->data);
+	i = i->prev;
+      }
+    }
+    else {
+      GList * i = GTS_OBJECT (s)->reserved;
+
+      while (i) {
+	*boundary = g_slist_prepend (*boundary, i->data);
+	i = i->next;
+      }
+    }
+  }
+}
+
+static void triangulate_face (GtsTriangle * t, GtsSurface * surface)
+{
+  GSList * interior = GTS_OBJECT (t)->reserved;
+  GSList * boundary = NULL;
+  GtsSurface * s = gts_surface_new (gts_surface_class (),
+				    surface->face_class,
+				    surface->edge_class,
+				    surface->vertex_class);
+  gdouble x, y, z;
+  GtsPoint * p = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
+  GtsPoint * o;
+
+  GTS_OBJECT (t)->reserved = NULL;  
+  gts_triangle_normal (t, &x, &y, &z);
+  g_assert (x != 0. || y != 0. || z != 0.);
+  o = gts_point_new (gts_point_class (), p->x + x, p->y + y, p->z + z);
+  add_boundary (GTS_SEGMENT (t->e3), GTS_SEGMENT (t->e1), &boundary);
+  add_boundary (GTS_SEGMENT (t->e2), GTS_SEGMENT (t->e3), &boundary);
+  add_boundary (GTS_SEGMENT (t->e1), GTS_SEGMENT (t->e2), &boundary);
+#ifdef DEBUG
+  {
+    static guint nt = 0;
+    char name[80];
+    FILE * fp;
+
+    fprintf (stderr, "%u: triangulating %p\n", nt, t);
+if (nt == 28)
+  fprintf (stderr, "tintin!!!!\n");
+    sprintf (name, "/tmp/oc.%u", nt++);
+    fp = fopen (name, "wt");
+    //    write_graph (boundary, interior, s, fp);
+    write_segments (boundary, interior, fp);
+    fclose (fp);
+  }
+#endif /* DEBUG */
+  triangulate_boundary_interior (boundary, interior, s, o);
+  g_slist_free (interior);
+  g_slist_free (boundary);
+  if (GTS_OBJECT (t)->klass->attributes)
+    gts_surface_foreach_face (s, (GtsFunc) gts_object_attributes, t);
+  gts_surface_merge (surface, s);
+  gts_object_destroy (GTS_OBJECT (s));
+  gts_object_destroy (GTS_OBJECT (o));
+}
+
+static void free_edge_list (GtsObject * o)
+{
+  g_list_free (o->reserved);
+  o->reserved = NULL;
+}
+
+/**
+ * gts_surface_inter_new:
+ * @klass: a #GtsSurfaceInterClass.
+ * @s1: a #GtsSurface.
+ * @s2: a #GtsSurface.
+ * @faces_tree1: a bounding box tree (see gts_bb_tree_new()) for
+ * the faces of @s1.
+ * @faces_tree2: a bounding box tree for the faces of @s2.
+ * @is_open1: whether @s1 is an "open" surface.
+ * @is_open2: whether @s2 is an "open" surface.
+ *
+ * When triangulating the cut faces, the new faces inherit the
+ * attributes of these original faces through their attributes()
+ * method.
+ *
+ * Returns: a new #GtsSurfaceInter describing the intersection of @s1
+ * and @s2.  
+ */
+GtsSurfaceInter * gts_surface_inter_new (GtsSurfaceInterClass * klass,
+					 GtsSurface * s1,
+					 GtsSurface * s2,
+					 GNode * faces_tree1,
+					 GNode * faces_tree2,
+					 gboolean is_open1,
+					 gboolean is_open2)
+{
+  GtsSurfaceInter * si;
+  GtsSurface * s;
+
+  g_return_val_if_fail (klass != NULL, NULL);
+  g_return_val_if_fail (s1 != NULL, NULL);
+  g_return_val_if_fail (s2 != NULL, NULL);
+  g_return_val_if_fail (faces_tree1 != NULL, NULL);
+  g_return_val_if_fail (faces_tree2 != NULL, NULL);
+
+  si = surface_inter_new (klass, s1, s2, faces_tree1, faces_tree2);
+
+  gts_surface_foreach_edge (si->s1, (GtsFunc) create_edges, si->s1);
+  gts_surface_foreach_edge (si->s2, (GtsFunc) create_edges, si->s2);
+
+#ifdef DEBUG
+  fprintf (stderr, "====== triangulating s1 ======\n");
+#endif /* DEBUG */
+  s = gts_surface_new (gts_surface_class (),
+		       s1->face_class,
+		       s1->edge_class,
+		       s1->vertex_class);
+  gts_surface_foreach_face (si->s1, (GtsFunc) triangulate_face, s);
+  gts_surface_foreach_edge (si->s1, (GtsFunc) free_edge_list, NULL);
+  gts_object_destroy (GTS_OBJECT (si->s1));
+  si->s1 = s;
+  GTS_OBJECT (si->s1)->reserved = s1;
+  
+#ifdef DEBUG
+  fprintf (stderr, "====== triangulating s2 ======\n");
+#endif /* DEBUG */
+  s = gts_surface_new (gts_surface_class (),
+		       s2->face_class,
+		       s2->edge_class,
+		       s2->vertex_class);
+  gts_surface_foreach_face (si->s2, (GtsFunc) triangulate_face, s);
+  gts_surface_foreach_edge (si->s2, (GtsFunc) free_edge_list, NULL);
+  gts_object_destroy (GTS_OBJECT (si->s2));
+  si->s2 = s;
+  GTS_OBJECT (si->s2)->reserved = s2;
+
+  return si;
+}
+
+static void check_surface_edge (GtsEdge * e, gpointer * data)
+{
+  gboolean * ok = data[0];
+  GtsSurface * s = data[1];
+  GtsSurface * bs = GTS_OBJECT (s)->reserved;
+  guint nf = gts_edge_face_number (e, s);
+
+  if (nf < 1 || nf > 2) {
+    *ok = FALSE;
+    g_return_if_fail (nf >= 1 && nf <= 2);
+  }
+  if (nf == 1 && gts_edge_face_number (e, bs) == 0) {
+    *ok = FALSE;
+    g_return_if_fail (gts_edge_face_number (e, bs) > 0);
+  }
+}
+
+static void mark_edge (GtsObject * o, gpointer data)
+{
+  o->reserved = data;
+}
+
+static gint triangle_orientation (GtsTriangle * t, GtsEdge * e)
+{
+  GtsSegment * s = GTS_SEGMENT (t->e1 == e ? t->e2 
+				: 
+				t->e2 == e ? t->e3 
+				: 
+				t->e1);
+  GtsVertex * v2 = GTS_SEGMENT (e)->v2;
+
+  if (s->v1 == v2 || s->v2 == v2)
+    return 1;
+  return -1;
+}
+
+static gboolean check_orientation (GtsEdge * e, GtsSurface * s)
+{
+  GtsTriangle * t1 = NULL, * t2 = NULL;
+  GSList * i = e->triangles;
+  gint o1 = 0, o2 = 0;
+
+  while (i) {
+    if (GTS_IS_FACE (i->data) && 
+	gts_face_has_parent_surface (i->data, s)) {
+      if (t1 == NULL) {
+	t1 = i->data;
+	o1 = triangle_orientation (t1, e);
+      }
+      else if (t2 == NULL) {
+	t2 = i->data;
+	o2 = triangle_orientation (t2, e);
+	g_return_val_if_fail (o1*o2 < 0, FALSE);
+      }
+      else
+	g_assert_not_reached ();
+    }
+    i = i->next;
+  }
+  g_return_val_if_fail (t1 && t2, FALSE);
+  return TRUE;
+}
+
+static void check_edge (GtsSegment * s, gpointer * data)
+{
+  gboolean * ok = data[0];
+  GtsSurfaceInter * si = data[1];
+  gboolean * closed = data[2];
+  GSList * j;
+  guint nn = 0;
+  
+  j = s->v1->segments;
+  while (j && *ok) {
+    GtsSegment * s1 = j->data;
+    
+    if (s1 != s && GTS_OBJECT (s1)->reserved == si) {
+      if (s1->v2 != s->v1)
+	*ok = FALSE;
+      nn++;
+    }
+    j = j->next;
+  }
+  j = s->v2->segments;
+  while (j && *ok) {
+    GtsSegment * s1 = j->data;
+    
+    if (s1 != s && GTS_OBJECT (s1)->reserved == si) {
+      if (s1->v1 != s->v2)
+	*ok = FALSE;
+      nn++;
+    }
+    j = j->next;
+  }
+  if (nn != 2)
+    *closed = FALSE;
+
+  if (!check_orientation (GTS_EDGE (s), si->s1))
+    *ok = FALSE;
+  if (!check_orientation (GTS_EDGE (s), si->s2))
+    *ok = FALSE;
+}
+
+/**
+ * gts_surface_inter_check:
+ * @si: a #GtsSurfaceInter.
+ * @closed: is set to %TRUE if @si->edges is a closed curve, %FALSE
+ * otherwise.
+ *
+ * Returns: %TRUE if the curve described by @si is an orientable
+ * manifold, %FALSE otherwise.  
+ */
+gboolean gts_surface_inter_check (GtsSurfaceInter * si,
+				  gboolean * closed)
+{
+  gboolean ok = TRUE;
+  gpointer data[3];
+
+  g_return_val_if_fail (si != NULL, FALSE);
+  g_return_val_if_fail (closed != NULL, FALSE);
+
+  *closed = si->edges ? TRUE : FALSE;
+
+  /* mark edges as used by si */
+  g_slist_foreach (si->edges, (GFunc) mark_edge, si);
+
+  data[0] = &ok;
+  data[1] = si;
+  data[2] = closed;
+  g_slist_foreach (si->edges, (GFunc) check_edge, data);
+  g_slist_foreach (si->edges, (GFunc) gts_object_reset_reserved, NULL);
+
+  /* check connectivity of the faces of @si */
+  if (*closed) {
+    gpointer data[2];
+
+    data[0] = &ok;
+    data[1] = si->s1;
+    gts_surface_foreach_edge (si->s1, (GtsFunc) check_surface_edge, data);
+    data[1] = si->s2;
+    gts_surface_foreach_edge (si->s2, (GtsFunc) check_surface_edge, data);
+  }
+
+  return ok;
+}
+
+/* Given @e and @f returns a #GtsFace compatible with @f and belonging to
+   @s1 or @s2 */
+static GtsFace * next_compatible_face (GtsEdge * e, 
+				       GtsFace * f, 
+				       GtsSurface * s1,
+				       GtsSurface * s2)
+{
+  GSList * i = e->triangles;
+  GtsFace * f2 = NULL, * f3 = NULL;
+
+  while (i) {
+    GtsFace * f1 = i->data;
+
+    if (f1 != f && GTS_IS_FACE (f1)) {
+      if (gts_face_has_parent_surface (f1, s1))
+	return f1;
+      if (gts_face_has_parent_surface (f1, s2)) {
+	if (f2 == NULL) f2 = f1;
+	else if (f3 == NULL) f3 = f1;
+	else g_assert_not_reached (); /* s2 is a non-manifold surface */
+      }
+    }
+    i = i->next;
+  }
+  if (f3 == NULL) {
+    if (gts_edge_is_boundary (e, s2))
+      return NULL;
+    return f2; 
+  }
+  g_assert (gts_face_has_parent_surface (f, s1));
+  if (gts_triangles_are_compatible (GTS_TRIANGLE (f), GTS_TRIANGLE (f2), e))
+    return f2;
+  return f3;
+}
+
+static void walk_faces (GtsEdge * e, GtsFace * f, 
+			GtsSurface * s1,
+			GtsSurface * s2,
+			GtsSurface * s)
+{
+  GtsFifo * faces = gts_fifo_new ();
+  GtsFifo * edges = gts_fifo_new ();
+
+  gts_fifo_push (faces, f);
+  gts_fifo_push (edges, e);
+  while ((f = gts_fifo_pop (faces)) && (e = gts_fifo_pop (edges))) {
+    if (!GTS_OBJECT (f)->reserved) {
+      GtsTriangle * t = GTS_TRIANGLE (f);
+      GtsFace * f1;
+
+      gts_surface_add_face (s, f);
+      GTS_OBJECT (f)->reserved = s;
+      if (t->e1 != e && !GTS_OBJECT (t->e1)->reserved &&
+	  (f1 = next_compatible_face (t->e1, f, s1, s2))) {
+	gts_fifo_push (faces, f1);
+	gts_fifo_push (edges, t->e1);
+      }	
+      if (t->e2 != e && !GTS_OBJECT (t->e2)->reserved &&
+	  (f1 = next_compatible_face (t->e2, f, s1, s2))) {
+	gts_fifo_push (faces, f1);
+	gts_fifo_push (edges, t->e2);
+      }	
+      if (t->e3 != e && !GTS_OBJECT (t->e3)->reserved &&
+	  (f1 = next_compatible_face (t->e3, f, s1, s2))) {
+	gts_fifo_push (faces, f1);
+	gts_fifo_push (edges, t->e3);
+      }	
+    }
+  }
+  gts_fifo_destroy (faces);
+  gts_fifo_destroy (edges);
+}
+
+/**
+ * gts_surface_inter_boolean:
+ * @si: a #GtsSurfaceInter.
+ * @surface: a #GtsSurface.
+ * @op: a #GtsBooleanOperation.
+ *
+ * Adds to @surface the part of the surface described by @si and @op.
+ */
+void gts_surface_inter_boolean (GtsSurfaceInter * si,
+				GtsSurface * surface,
+				GtsBooleanOperation op)
+{
+  GtsSurface * s = NULL;
+  gint orient = 1;
+  GSList * i;
+
+  g_return_if_fail (si != NULL);
+  g_return_if_fail (surface != NULL);
+
+  switch (op) {
+  case GTS_1_OUT_2: s = si->s1; orient = 1; break;
+  case GTS_1_IN_2: s = si->s1; orient = -1; break;
+  case GTS_2_OUT_1: s = si->s2; orient = -1; break;
+  case GTS_2_IN_1: s = si->s2; orient = 1; break;
+  default: g_assert_not_reached ();
+  }
+
+  /* mark edges as belonging to intersection */
+  g_slist_foreach (si->edges, (GFunc) mark_edge, si);
+
+  i = si->edges;
+  while (i) {
+    GtsEdge * e = i->data;
+    GSList * j = e->triangles;
+    
+    while (j) {
+      if (gts_face_has_parent_surface (j->data, s) &&
+	  orient*triangle_orientation (j->data, e) > 0) {
+#ifdef DEBUG_BOOLEAN
+	GtsFace * boundary = gts_edge_is_boundary (e, surface);
+
+	g_assert (!boundary || boundary == j->data);
+#endif /* DEBUG_BOOLEAN */
+	walk_faces (e, j->data, s, GTS_OBJECT (s)->reserved, surface);
+	break;
+      }
+      j = j->next;
+    }
+    i = i->next;
+  }
+  g_slist_foreach (si->edges, (GFunc) gts_object_reset_reserved, NULL);
+  gts_surface_foreach_face (surface, 
+			    (GtsFunc) gts_object_reset_reserved, NULL);
+}
+
+static void self_intersecting (GtsBBox * bb1, GtsBBox * bb2, 
+			       gpointer * d)
+{
+  GtsTriangle * t1 = bb1->bounded;
+  GtsTriangle * t2 = bb2->bounded;
+
+  if (t1 != t2) {
+    GtsSegment * s1 = GTS_SEGMENT (t1->e1);
+    GtsSegment * s2 = GTS_SEGMENT (t1->e2);
+    GtsSegment * s3 = GTS_SEGMENT (t1->e3);
+    GtsSegment * s4 = GTS_SEGMENT (t2->e1);
+    GtsSegment * s5 = GTS_SEGMENT (t2->e2);
+    GtsSegment * s6 = GTS_SEGMENT (t2->e3);
+    GtsPoint * pi;
+
+    if ((!gts_segments_touch (s4, s1) && 
+	 !gts_segments_touch (s4, s2) &&
+	 !gts_segments_touch (s4, s3) &&
+	 (pi = segment_triangle_intersection (s4, t1, gts_point_class ()))
+	 != NULL) ||
+	(!gts_segments_touch (s5, s1) && 
+	 !gts_segments_touch (s5, s2) &&
+	 !gts_segments_touch (s5, s3) &&
+	 (pi = segment_triangle_intersection (s5, t1, gts_point_class ())) 
+	 != NULL) ||
+	(!gts_segments_touch (s6, s1) && 
+	 !gts_segments_touch (s6, s2) &&
+	 !gts_segments_touch (s6, s3) &&
+	 (pi = segment_triangle_intersection (s6, t1, gts_point_class ())) 
+	 != NULL)) {
+      GtsBBTreeTraverseFunc func = d[0];
+      gpointer data = d[1];
+      gboolean * self_inter = d[2];
+
+      gts_object_destroy (GTS_OBJECT (pi));
+      *self_inter = TRUE;
+      (* func) (bb1, bb2, data);
+    }
+  }
+}
+
+/**
+ * gts_surface_foreach_intersecting_face:
+ * @s: a #GtsSurface.
+ * @func: a #GtsBBTreeTraverseFunc.
+ * @data: user data to pass to @func.
+ *
+ * Calls @func for each intersecting pair of faces of @s.
+ *
+ * Returns: %TRUE if @func was called at least once, %FALSE otherwise.
+ */
+gboolean gts_surface_foreach_intersecting_face (GtsSurface * s,
+						GtsBBTreeTraverseFunc func,
+						gpointer data)
+{
+  GNode * tree;
+  gpointer d[3];
+  gboolean self_inter = FALSE;
+
+  g_return_val_if_fail (s != NULL, FALSE);
+  g_return_val_if_fail (func != NULL, FALSE);
+
+  tree = gts_bb_tree_surface (s);
+  d[0] = func;
+  d[1] = data;
+  d[2] = &self_inter;
+  gts_bb_tree_traverse_overlapping (tree, tree, 
+				    (GtsBBTreeTraverseFunc) self_intersecting,
+				    d);
+  gts_bb_tree_destroy (tree, TRUE);
+
+  return self_inter;
+}
+
+static void add_intersecting (GtsBBox * bb1, GtsBBox * bb2, 
+			      GtsSurface * intersected)
+{
+  gts_surface_add_face (intersected, bb1->bounded);
+  gts_surface_add_face (intersected, bb2->bounded);
+}
+
+/**
+ * gts_surface_is_self_intersecting:
+ * @s: a #GtsSurface.
+ *
+ * Returns: a new #GtsSurface containing the faces of @s which are
+ * self-intersecting or %NULL if no faces of @s are self-intersecting.
+ */
+GtsSurface * gts_surface_is_self_intersecting (GtsSurface * s)
+{
+  GtsSurface * intersected;
+
+  g_return_val_if_fail (s != NULL, NULL);
+
+  intersected = gts_surface_new (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass),
+				 s->face_class,
+				 s->edge_class,
+				 s->vertex_class);
+  if (!gts_surface_foreach_intersecting_face (s,
+		      (GtsBBTreeTraverseFunc) add_intersecting, intersected)) {
+    gts_object_destroy (GTS_OBJECT (intersected));
+    intersected = NULL;
+  }
+  return intersected;
+}
diff --git a/gts/cdt.c b/gts/cdt.c
new file mode 100644
index 0000000..2038ab5
--- /dev/null
+++ b/gts/cdt.c
@@ -0,0 +1,1175 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+
+#include <math.h>
+#include "gts.h"
+
+#ifdef USE_SURFACE_BTREE
+
+static gint find_closest (GtsTriangle * t, gpointer value, gpointer * data)
+{
+  guint * ns = data[2];
+  guint * n = data[3];
+
+  if (*n >= *ns)
+    return TRUE;
+  else {
+    gdouble * dmin = data[0];
+    gpointer * closest = data[1];
+    GtsPoint * p = data[4];
+
+    if (gts_triangle_orientation (t) > 0.) {
+      GtsPoint * p1 = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
+      gdouble d = (p->x - p1->x)*(p->x - p1->x) + (p->y - p1->y)*(p->y - p1->y);
+      
+      if (d < *dmin) {
+	*dmin = d;
+	*closest = t;
+      }
+      (*n)++;
+    }
+  }
+  return FALSE;
+}
+
+/* select the face closest to @p among n^1/3 randomly picked faces
+ *  of @surface */
+static GtsFace * closest_face (GtsSurface * s, GtsPoint * p)
+{
+  guint n = 0, nt, ns;
+  gdouble dmin = G_MAXDOUBLE;
+  GtsFace * closest = NULL;
+  gpointer data[5];
+
+  nt = gts_surface_face_number (s);
+  if (!nt)
+    return NULL;
+  ns = exp (log ((gdouble) nt)/3.);
+
+  data[0] = &dmin;
+  data[1] = &closest;
+  data[2] = &ns;
+  data[3] = &n;
+  data[4] = p;
+  g_tree_traverse (s->faces, (GTraverseFunc) find_closest, G_IN_ORDER, data);
+
+  return closest;
+}
+
+#else /* not USE_SURFACE_BTREE */
+
+typedef struct _SFindClosest SFindClosest; 
+
+struct _SFindClosest {
+  gdouble dmin; 
+  GtsFace *closest;
+  GtsPoint * p;
+  gint stop;
+};
+
+#  if GLIB_CHECK_VERSION(2,4,0)
+/* finally, with g_hash_table_find we are able to stop iteration over the hash
+   table in the middle */
+
+static gboolean find_closest (gpointer key, gpointer value, gpointer user_data)
+{
+  SFindClosest * data = (SFindClosest *) user_data;
+  GtsFace * f = GTS_FACE (value);
+  
+  if (gts_triangle_orientation (GTS_TRIANGLE (f)) > 0.) {
+    GtsPoint * p1 = GTS_POINT (GTS_SEGMENT (GTS_TRIANGLE (f)->e1)->v1);
+    gdouble d = ((data->p->x - p1->x)*(data->p->x - p1->x) + 
+		 (data->p->y - p1->y)*(data->p->y - p1->y));
+
+    if (d < data->dmin) {
+      data->dmin = d;
+      data->closest = f;
+    }
+  }
+  data->stop--;
+  return !(data->stop > 0);
+}
+
+static GtsFace * closest_face (GtsSurface * s, GtsPoint * p)
+{
+  SFindClosest fc;
+
+  fc.dmin = G_MAXDOUBLE;
+  fc.closest = NULL;
+  fc.p = p;
+  fc.stop = (gint) exp (log ((gdouble) g_hash_table_size (s->faces))/3.);
+  g_hash_table_find (s->faces, find_closest, &fc);
+  
+  return fc.closest;
+}
+
+#  else /* VERSION < 2.4.0 */
+
+static void
+find_closest (gpointer key, gpointer value, gpointer user_data)
+{
+  SFindClosest * data = (SFindClosest *) user_data;
+  GtsFace * f = GTS_FACE (value);
+
+  if (gts_triangle_orientation (GTS_TRIANGLE (f)) > 0.) {
+    GtsPoint * p1 = GTS_POINT (GTS_SEGMENT (GTS_TRIANGLE (f)->e1)->v1);
+    gdouble d = ((data->p->x - p1->x)*(data->p->x - p1->x) +
+		 (data->p->y - p1->y)*(data->p->y - p1->y));
+
+    if (d < data->dmin) {
+      data->dmin = d;
+      data->closest = f;
+    }
+  }
+  data->stop--;
+}
+
+/* select the face closest to @p among n^1/3 randomly picked faces
+ * of @surface */
+static GtsFace * closest_face (GtsSurface * s, GtsPoint * p)
+{
+  SFindClosest fc;
+
+  if (!g_hash_table_size (s->faces))
+    return NULL;
+
+  fc.dmin = G_MAXDOUBLE;
+  fc.closest = NULL;
+  fc.p = p;
+  fc.stop = (gint) exp (log ((gdouble) g_hash_table_size (s->faces))/3.);
+  g_hash_table_foreach (s->faces, find_closest, &fc);
+  return fc.closest;
+}
+#  endif /* VERSION < 2.4.0 */
+#endif /* not USE_SURFACE_BTREE */
+
+/* returns the face belonging to @surface and neighbor of @f via @e */
+static GtsFace * neighbor (GtsFace * f,
+			   GtsEdge * e,
+			   GtsSurface * surface)
+{
+  GSList * i = e->triangles;
+  GtsTriangle * t = GTS_TRIANGLE (f);
+
+  while (i) {
+    GtsTriangle * t1 = i->data;
+    if (t1 != t &&
+	GTS_IS_FACE (t1) &&
+	gts_face_has_parent_surface (GTS_FACE (t1), surface))
+      return GTS_FACE (t1);
+    i = i->next;
+  }
+  return NULL;
+}
+
+/* given a triangle @t and a segment s (@o -> @p). 
+   @o must be in @t. Returns the
+   edge of @t which is intersected by s or %NULL if @p is also
+   contained in @t (on_summit is set to %FALSE) or if s intersects @t 
+   exactly on one of its summit (on_summit is set to %TRUE). */
+static GtsEdge * triangle_next_edge (GtsTriangle * t,
+				     GtsPoint * o, GtsPoint * p,
+				     gboolean * on_summit)
+{
+  GtsVertex * v1, * v2, * v3;
+  GtsEdge * e1, * e2, * e3;
+  gdouble orient = 0.0;
+  
+  gts_triangle_vertices_edges (t, NULL,
+			       &v1, &v2, &v3, 
+			       &e1, &e2, &e3);
+
+  *on_summit = FALSE;
+  orient = gts_point_orientation (o, GTS_POINT (v1), p);
+  if (orient > 0.0) {
+    orient = gts_point_orientation (o, GTS_POINT (v2), p);
+    if (orient > 0.0) {
+      if (gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), p) >= 0.0)
+	return NULL;
+      return e2;
+    }
+    if (orient < 0.0) {
+      if (gts_point_orientation (GTS_POINT (v1), GTS_POINT (v2), p) >= 0.0)
+	return NULL;
+      return e1;
+    }
+    if (gts_point_orientation (GTS_POINT (v1), GTS_POINT (v2), p) < 0.0)
+      *on_summit = TRUE;
+    return NULL;
+  }
+
+  if (orient < 0.0) {
+    orient = gts_point_orientation (o, GTS_POINT (v3), p);
+    if (orient > 0.0) {
+      if (gts_point_orientation (GTS_POINT (v3), GTS_POINT (v1), p) >= 0.0)
+	return NULL;
+      return e3;
+    }
+    if (orient < 0.0) {
+      if (gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), p) >= 0.0)
+	return NULL;
+      return e2;
+    }
+    if (gts_point_orientation (GTS_POINT (v3), GTS_POINT (v1), p) < 0.0)
+      *on_summit = TRUE;
+    return NULL;
+  }
+  
+  if (gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), p) < 0.0)
+    return e2;
+  if (gts_point_orientation (GTS_POINT (v1), GTS_POINT (v2), p) < 0.0)
+    *on_summit = TRUE;
+  return NULL;
+}
+
+static void triangle_barycenter (GtsTriangle * t, GtsPoint * b)
+{
+  GtsPoint * p = GTS_POINT (gts_triangle_vertex (t));
+  b->x = (p->x + 
+	  GTS_POINT (GTS_SEGMENT(t->e1)->v1)->x +
+	  GTS_POINT (GTS_SEGMENT(t->e1)->v2)->x)/3.;
+  b->y = (p->y + 
+	  GTS_POINT (GTS_SEGMENT(t->e1)->v1)->y +
+	  GTS_POINT (GTS_SEGMENT(t->e1)->v2)->y)/3.;
+}
+
+static GtsFace * point_locate (GtsPoint * o,
+			       GtsPoint * p,
+			       GtsFace * f,
+			       GtsSurface * surface)
+{
+  GtsEdge * prev;
+  gboolean on_summit;
+  GtsVertex * v1, * v2, * v3;
+  GtsEdge * e2, * e3;    
+  
+  prev = triangle_next_edge (GTS_TRIANGLE (f), o, p, &on_summit);
+
+  if (!prev) {
+    GtsFace * f1;
+
+    if (!on_summit)
+      return f; /* p is inside f */
+
+    /* s intersects f exactly on a summit: restarts from a neighbor of f */
+    if ((f1 = neighbor (f, GTS_TRIANGLE (f)->e1, surface)) ||
+	(f1 = neighbor (f, GTS_TRIANGLE (f)->e2, surface)) ||
+	(f1 = neighbor (f, GTS_TRIANGLE (f)->e3, surface))) {
+      triangle_barycenter (GTS_TRIANGLE (f1), o);
+      return point_locate (o, p, f1, surface);
+    }
+    return NULL;
+  }
+  
+  f = neighbor (f, prev, surface);
+  if (f)
+    gts_triangle_vertices_edges (GTS_TRIANGLE (f), prev, 
+				 &v1, &v2, &v3, &prev, &e2, &e3);
+  while (f) {
+    gdouble orient = gts_point_orientation (o, GTS_POINT (v3), p);
+
+    if (orient < 0.0) {
+      if (gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), p) >= 0.0)
+	return f; /* p is inside f */
+      f = neighbor (f, e2, surface);
+      prev = e2;
+      v1 = v3;      
+    }
+    else if (orient > 0.0) {
+      if (gts_point_orientation (GTS_POINT (v3), GTS_POINT (v1), p) >= 0.0)
+	return f; /* p is inside f */
+      f = neighbor (f, e3, surface);
+      prev = e3;
+      v2 = v3;
+    }
+    else {
+      GtsFace * f1;
+
+      if (gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), p) >= 0.0)
+	return f; /* p is inside f */
+
+      /* s intersects f exactly on v3: restarts from a neighbor of f */
+      if ((f1 = neighbor (f, e2, surface)) ||
+	  (f1 = neighbor (f, e3, surface))) {
+	triangle_barycenter (GTS_TRIANGLE (f1), o);
+	return point_locate (o, p, f1, surface);
+      }
+      return NULL;
+    }
+    /* update e2, e3, v3 for the new triangle */
+    if (f) {
+      if (prev == GTS_TRIANGLE (f)->e1) {
+	e2 = GTS_TRIANGLE (f)->e2; e3 = GTS_TRIANGLE (f)->e3;
+      }
+      else if (prev == GTS_TRIANGLE (f)->e2) {
+	e2 = GTS_TRIANGLE (f)->e3; e3 = GTS_TRIANGLE (f)->e1;
+      }
+      else {
+	e2 = GTS_TRIANGLE (f)->e1; e3 = GTS_TRIANGLE (f)->e2;
+      }
+      if (GTS_SEGMENT (e2)->v1 == v1 || GTS_SEGMENT (e2)->v1 == v2)
+	v3 = GTS_SEGMENT (e2)->v2;
+      else
+	v3 = GTS_SEGMENT (e2)->v1;
+    }
+  }
+  return NULL;
+}
+
+/**
+ * gts_point_locate:
+ * @p: a #GtsPoint.
+ * @surface: a #GtsSurface.
+ * @guess: %NULL or a face of @surface close to @p.
+ *
+ * Locates the face of the planar projection of @surface containing
+ * @p. The planar projection of @surface must define a connected set
+ * of triangles without holes and bounded by a convex boundary. The
+ * algorithm is randomized and performs in O(n^1/3) expected time
+ * where n is the number of triangles of @surface.
+ *
+ * If a good @guess is given the point location can be significantly faster.
+ *
+ * Returns: a #GtsFace of @surface containing @p or %NULL if @p is not
+ * contained within the boundary of @surface.  
+ */
+GtsFace * gts_point_locate (GtsPoint * p, 
+			    GtsSurface * surface,
+			    GtsFace * guess)
+{
+  GtsFace * fr;
+  GtsPoint * o;
+
+  g_return_val_if_fail (p != NULL, NULL);
+  g_return_val_if_fail (surface != NULL, NULL);
+  g_return_val_if_fail (guess == NULL || 
+			gts_face_has_parent_surface (guess, surface), NULL);
+
+  if (guess == NULL)
+    guess = closest_face (surface, p);
+  else
+    g_return_val_if_fail (gts_triangle_orientation (GTS_TRIANGLE (guess)) > 0., NULL);
+
+  if (guess == NULL)
+    return NULL;
+
+  o = GTS_POINT (gts_object_new (GTS_OBJECT_CLASS (gts_point_class ())));
+  triangle_barycenter (GTS_TRIANGLE (guess), o);
+  fr = point_locate (o, p, guess, surface);
+  gts_object_destroy (GTS_OBJECT (o));
+
+  return fr;
+}
+
+
+/**
+ * gts_constraint_class:
+ *
+ * Returns: the #GtsConstraintClass.
+ */
+GtsConstraintClass * gts_constraint_class (void)
+{
+  static GtsConstraintClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo constraint_info = {
+      "GtsConstraint",
+      sizeof (GtsConstraint),
+      sizeof (GtsConstraintClass),
+      (GtsObjectClassInitFunc) NULL,
+      (GtsObjectInitFunc) NULL,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_edge_class ()), 
+				  &constraint_info);
+  }
+
+  return klass;
+}
+
+static void split_list (GtsListFace * f, GtsListFace * f1, GtsListFace * f2, 
+			GtsPoint * p1, GtsPoint * p2,
+			GSList ** last1, GSList ** last2)
+{
+  GSList * i = f->points, * l1 = *last1, * l2 = *last2;
+
+  while (i) {
+    GtsPoint * p = i->data;
+    
+    if (gts_point_orientation (p1, p2, p) >= 0.) {
+      if (l1) l1->next = i; else f1->points = i;
+      l1 = i;
+    }
+    else {
+      if (l2) l2->next = i; else f2->points = i;
+      l2 = i;
+    }
+    i = i->next;
+  }
+  f->points = NULL;
+  *last1 = l1;
+  *last2 = l2;
+}
+
+/* cf. figure misc/swap.fig */
+static void swap_if_in_circle (GtsFace * f1,
+			       GtsVertex * v1, 
+			       GtsVertex * v2, 
+			       GtsVertex * v3,
+			       GtsEdge * e1, 
+			       GtsEdge * e2, 
+			       GtsEdge * e3,
+			       GtsSurface * surface)
+{
+  GtsFace * f2;
+  GtsEdge * e4, *e5;
+  GtsVertex * v4;
+
+  if (GTS_IS_CONSTRAINT (e1)) /* @e1 is a constraint can not swap */
+    return;
+
+  f2 = neighbor (f1, e1, surface);
+  if (f2 == NULL) /* @e1 is a boundary of @surface */
+    return;
+
+  if (GTS_TRIANGLE (f2)->e1 == e1) {
+    e4 = GTS_TRIANGLE (f2)->e2; e5 = GTS_TRIANGLE (f2)->e3;
+  }
+  else if (GTS_TRIANGLE (f2)->e2 == e1) {
+    e4 = GTS_TRIANGLE (f2)->e3; e5 = GTS_TRIANGLE (f2)->e1;
+  }
+  else {
+    e4 = GTS_TRIANGLE (f2)->e1; e5 = GTS_TRIANGLE (f2)->e2;
+  }
+  if (GTS_SEGMENT (e4)->v1 == GTS_SEGMENT (e1)->v1 || 
+      GTS_SEGMENT (e4)->v1 == GTS_SEGMENT (e1)->v2)
+    v4 = GTS_SEGMENT (e4)->v2;
+  else
+    v4 = GTS_SEGMENT (e4)->v1;
+
+  if (gts_point_in_circle (GTS_POINT (v4), GTS_POINT (v1), 
+			   GTS_POINT (v2), GTS_POINT (v3)) > 0.0) {
+    GtsEdge * en;
+    GtsSegment * sn = gts_vertices_are_connected (v3, v4);
+    GtsFace * f3, * f4;
+
+    if (!GTS_IS_EDGE (sn))
+      en = gts_edge_new (surface->edge_class, v3, v4);
+    else
+      en = GTS_EDGE (sn);
+
+    f3 = gts_face_new (surface->face_class, en, e5, e2);
+    gts_object_attributes (GTS_OBJECT (f3), GTS_OBJECT (f1));
+    f4 = gts_face_new (surface->face_class, en, e3, e4);
+    gts_object_attributes (GTS_OBJECT (f4), GTS_OBJECT (f2));
+    
+    if (GTS_IS_LIST_FACE (f3)) {
+      GSList * last3 = NULL, * last4 = NULL;
+
+      if (GTS_IS_LIST_FACE (f1))
+	split_list (GTS_LIST_FACE (f1), GTS_LIST_FACE (f3), GTS_LIST_FACE (f4),
+		    GTS_POINT (v3), GTS_POINT (v4), &last3, &last4);
+      if (GTS_IS_LIST_FACE (f2))
+	split_list (GTS_LIST_FACE (f2), GTS_LIST_FACE (f3), GTS_LIST_FACE (f4),
+		    GTS_POINT (v3), GTS_POINT (v4), &last3, &last4);
+      if (last3) last3->next = NULL;
+      if (last4) last4->next = NULL;
+    }
+
+    gts_surface_remove_face (surface, f1);
+    gts_surface_remove_face (surface, f2);
+    gts_surface_add_face (surface, f3);
+    gts_surface_add_face (surface, f4);
+
+    swap_if_in_circle (f3, v4, v2, v3, e5, e2, en, surface);
+    swap_if_in_circle (f4, v1, v4, v3, e4, en, e3, surface);
+  }
+}
+
+/**
+ * gts_delaunay_add_vertex_to_face:
+ * @surface: a #GtsSurface.
+ * @v: a #GtsVertex.
+ * @f: a #GtsFace belonging to @surface.
+ *
+ * Adds vertex @v to the face @f of the Delaunay triangulation defined
+ * by @surface.
+ *
+ * Returns: %NULL is @v has been successfully added to @surface or was
+ * already contained in @surface or a #GtsVertex having the same x and
+ * y coordinates as @v.  
+ */
+GtsVertex * gts_delaunay_add_vertex_to_face (GtsSurface * surface, 
+					     GtsVertex * v,
+					     GtsFace * f)
+{
+  GtsEdge * e1, * e2, * e3;
+  GtsSegment * s4, * s5, * s6;
+  GtsEdge * e4, * e5, * e6;
+  GtsVertex * v1, * v2, * v3;
+  GtsFace * nf[3];
+
+  g_return_val_if_fail (surface != NULL, v);
+  g_return_val_if_fail (v != NULL, v);
+  g_return_val_if_fail (f != NULL, v);
+
+  gts_triangle_vertices_edges (GTS_TRIANGLE (f), NULL, 
+			       &v1, &v2, &v3, &e1, &e2, &e3);
+  if (v == v1 || v == v2 || v == v3) /* v already in @surface */
+    return NULL;
+  if (GTS_POINT (v)->x == GTS_POINT (v1)->x &&
+      GTS_POINT (v)->y == GTS_POINT (v1)->y)
+    return v1;
+  if (GTS_POINT (v)->x == GTS_POINT (v2)->x &&
+      GTS_POINT (v)->y == GTS_POINT (v2)->y)
+    return v2;
+  if (GTS_POINT (v)->x == GTS_POINT (v3)->x &&
+      GTS_POINT (v)->y == GTS_POINT (v3)->y)
+    return v3;
+
+  s4 = gts_vertices_are_connected (v, v1);
+  if (!GTS_IS_EDGE (s4))
+    e4 = gts_edge_new (surface->edge_class, v, v1);
+  else
+    e4 = GTS_EDGE (s4);
+  s5 = gts_vertices_are_connected (v, v2);
+  if (!GTS_IS_EDGE (s5))
+    e5 = gts_edge_new (surface->edge_class, v, v2);
+  else
+    e5 = GTS_EDGE (s5);
+  s6 = gts_vertices_are_connected (v, v3);
+  if (!GTS_IS_EDGE (s6))
+    e6 = gts_edge_new (surface->edge_class, v, v3);
+  else
+    e6 = GTS_EDGE (s6);
+
+  /* cf. figure misc/swap.fig */
+  nf[0] = gts_face_new (surface->face_class, e4, e1, e5);
+  gts_object_attributes (GTS_OBJECT (nf[0]), GTS_OBJECT (f));
+  nf[1] = gts_face_new (surface->face_class, e5, e2, e6);
+  gts_object_attributes (GTS_OBJECT (nf[1]), GTS_OBJECT (f));
+  nf[2] = gts_face_new (surface->face_class, e6, e3, e4);
+  gts_object_attributes (GTS_OBJECT (nf[2]), GTS_OBJECT (f));
+
+  if (GTS_IS_LIST_FACE (f) && GTS_IS_LIST_FACE (nf[0])) {
+    GSList * i = GTS_LIST_FACE (f)->points, * last[3] = { NULL, NULL, NULL };
+
+    while (i) {
+      GtsPoint * p = i->data;
+      GSList * next = i->next;
+      guint j;
+      
+      if (p != GTS_POINT (v)) {
+	if (gts_point_orientation (GTS_POINT (v), GTS_POINT (v1), p) >= 0.) {
+	  gdouble o = gts_point_orientation (GTS_POINT (v), GTS_POINT (v2), p);
+
+	  if (o != 0.)
+	    j = o > 0. ? 1 : 0;
+	  else
+	    j = gts_point_orientation (GTS_POINT (v), GTS_POINT (v3), p) 
+	      > 0. ? 0 : 1;
+	}
+	else if (gts_point_orientation (GTS_POINT (v), GTS_POINT (v3), p) > 0.)
+	  j = 2;
+	else
+	  j = 1;
+	if (last[j])
+	  last[j]->next = i; 
+	else 
+	  GTS_LIST_FACE (nf[j])->points = i;
+	last[j] = i;
+      }
+      else
+	g_slist_free_1 (i);
+      i = next;
+    }
+    GTS_LIST_FACE (f)->points = NULL;
+    if (last[0]) last[0]->next = NULL;
+    if (last[1]) last[1]->next = NULL;
+    if (last[2]) last[2]->next = NULL;
+  }
+
+  gts_surface_remove_face (surface, f);
+  gts_surface_add_face (surface, nf[0]);
+  gts_surface_add_face (surface, nf[1]);
+  gts_surface_add_face (surface, nf[2]);
+
+  swap_if_in_circle (nf[0], v1, v2, v, e1, e5, e4, surface);
+  swap_if_in_circle (nf[1], v2, v3, v, e2, e6, e5, surface);
+  swap_if_in_circle (nf[2], v3, v1, v, e3, e4, e6, surface);
+
+  return NULL;
+}
+
+/** 
+ * gts_delaunay_add_vertex: 
+ * @surface: a #GtsSurface.  
+ * @v: a #GtsVertex.  
+ * @guess: %NULL or a #GtsFace belonging to @surface to be used as an initial
+ * guess for point location.
+ *
+ * Adds vertex @v to the Delaunay triangulation defined by
+ * @surface. If @v is not contained in the convex hull bounding
+ * @surface, @v is not added to the triangulation.
+ *
+ * Returns: %NULL is @v has been successfully added to @surface or was
+ * already contained in @surface, @v if @v is not contained in the
+ * convex hull bounding surface or a #GtsVertex having the same x and
+ * y coordinates as @v.  
+ */
+GtsVertex * gts_delaunay_add_vertex (GtsSurface * surface, 
+				     GtsVertex * v,
+				     GtsFace * guess)
+{
+  GtsFace * f;
+
+  g_return_val_if_fail (surface != NULL, v);
+  g_return_val_if_fail (v != NULL, v);
+
+  if (!(f = gts_point_locate (GTS_POINT (v), surface, guess)))
+    return v;
+  return gts_delaunay_add_vertex_to_face (surface, v, f);
+}
+
+static gboolean polygon_in_circle (GSList * poly,
+				   GtsPoint * p1, 
+				   GtsPoint * p2,
+				   GtsPoint * p3)
+{
+  GtsVertex * v1 = NULL, * v2 = NULL;
+
+  while (poly) {
+    GtsSegment * s = poly->data;
+    GtsVertex * v;
+    v = s->v1;
+    if (v != v1 && v != v2 &&
+	v != GTS_VERTEX (p1) &&
+	v != GTS_VERTEX (p2) &&
+	v != GTS_VERTEX (p3) &&
+	gts_point_in_circle (GTS_POINT (v), p1, p2, p3) > 0.)
+      return TRUE;
+    v = s->v2;
+    if (v != v1 && v != v2 &&
+	v != GTS_VERTEX (p1) &&
+	v != GTS_VERTEX (p2) &&
+	v != GTS_VERTEX (p3) &&
+	gts_point_in_circle (GTS_POINT (v), p1, p2, p3) > 0.)
+      return TRUE;
+    v1 = s->v1;
+    v2 = s->v2;
+    poly = poly->next;
+  }
+  return FALSE;
+}
+
+static void triangulate_polygon (GSList * poly, 
+				 GtsSurface * surface,
+				 GtsFace * ref)
+{
+  GSList * i, * poly1, * poly2;
+  GtsVertex * v1, * v2, * v3 = NULL;
+  gboolean found = FALSE;
+  GtsSegment * s, * s1, * s2;
+  GtsEdge * e1, * e2;
+  GtsFace * f;
+
+  if (poly == NULL || poly->next == NULL) {
+    g_slist_free (poly);
+    return;
+  }
+
+  s = poly->data;
+  s1 = poly->next->data;
+  if (s->v1 == s1->v1 || s->v1 == s1->v2) {
+    v1 = s->v2;
+    v2 = s->v1;
+  }
+  else {
+    g_assert (s->v2 == s1->v1 || s->v2 == s1->v2);
+    v1 = s->v1;
+    v2 = s->v2;
+  }
+
+  i = poly->next;
+  v3 = v2;
+  while (i && !found) {
+    s1 = i->data;
+    if (s1->v1 == v3)
+      v3 = s1->v2;
+    else {
+      g_assert (s1->v2 == v3);
+      v3 = s1->v1;
+    }
+    if (v3 != v1 &&
+	gts_point_orientation (GTS_POINT (v1), 
+			       GTS_POINT (v2), 
+			       GTS_POINT (v3)) >= 0. &&
+	!polygon_in_circle (poly, 
+			    GTS_POINT (v1), 
+			    GTS_POINT (v2), 
+			    GTS_POINT (v3)))
+      found = TRUE;
+    else 
+      i = i->next;
+  }
+
+  if (!found) {
+    g_slist_free (poly);
+    return;
+  }
+
+  s1 = gts_vertices_are_connected (v2, v3);
+  if (!GTS_IS_EDGE (s1))
+    e1 = gts_edge_new (surface->edge_class, v2, v3);
+  else
+    e1 = GTS_EDGE (s1);
+  s2 = gts_vertices_are_connected (v3, v1);
+  if (!GTS_IS_EDGE (s2))
+    e2 = gts_edge_new (surface->edge_class, v3, v1);
+  else
+    e2 = GTS_EDGE (s2);
+  f = gts_face_new (surface->face_class, GTS_EDGE (s), e1, e2);
+  gts_object_attributes (GTS_OBJECT (f), GTS_OBJECT (ref));
+  gts_surface_add_face (surface, f);
+
+  poly1 = poly->next;
+  g_slist_free_1 (poly);
+  if (i->next && e2 != i->next->data)
+    poly2 = g_slist_prepend (i->next, e2);
+  else
+    poly2 = i->next;
+  if (e1 != i->data)
+    i->next = g_slist_prepend (NULL, e1);
+  else
+    i->next = NULL;
+
+ triangulate_polygon (poly1, surface, ref);
+ triangulate_polygon (poly2, surface, ref);
+}
+
+/**
+ * gts_delaunay_remove_vertex:
+ * @surface: a #GtsSurface.
+ * @v: a #GtsVertex.
+ *
+ * Removes @v from the Delaunay triangulation defined by @surface and
+ * restores the Delaunay property. Vertex @v must not be used by any
+ * constrained edge otherwise the triangulation is not guaranteed to
+ * be Delaunay.  
+ */
+void gts_delaunay_remove_vertex (GtsSurface * surface, GtsVertex * v)
+{
+  GSList * triangles, * i;
+  GtsFace * ref = NULL;
+
+  g_return_if_fail (surface != NULL);
+  g_return_if_fail (v != NULL);
+
+  i = triangles = gts_vertex_triangles (v, NULL);
+  while (i && !ref) {
+    if (GTS_IS_FACE (i->data) &&
+	gts_face_has_parent_surface (i->data, surface))
+      ref = i->data;
+    i = i->next;
+  }
+  if (!ref) {
+    g_slist_free (triangles);
+    g_return_if_fail (ref);
+  }
+  triangulate_polygon (gts_vertex_fan_oriented (v, surface), surface, ref);
+  i = triangles;
+  while (i) {
+    if (GTS_IS_FACE (i->data) &&
+	gts_face_has_parent_surface (i->data, surface))
+      gts_surface_remove_face (surface, i->data);
+    i = i->next;
+  }
+  g_slist_free (triangles);
+}
+
+#define NEXT_CUT(edge, edge1, list) { next = neighbor (f, edge, surface);\
+                                      remove_triangles (e, surface);\
+                                      if (!constraint && !e->triangles)\
+				        gts_object_destroy (GTS_OBJECT (e));\
+                                      g_assert (next);\
+				      *list = g_slist_prepend (*list, edge1);\
+                                      return g_slist_concat (constraint,\
+                                        remove_intersected_edge (s, edge,\
+					       next, surface, left, right));\
+                                    }
+
+static void remove_triangles (GtsEdge * e, GtsSurface * s)
+{
+  GSList * i = e->triangles;
+
+  while (i) {
+    GSList * next = i->next;
+
+    if (GTS_IS_FACE (i->data) && gts_face_has_parent_surface (i->data, s))
+      gts_surface_remove_face (s, i->data);
+    i = next;
+  }
+}
+
+static GSList * 
+remove_intersected_edge (GtsSegment * s,
+			 GtsEdge * e,
+			 GtsFace * f,
+			 GtsSurface * surface,
+			 GSList ** left, GSList ** right)
+{
+  GtsVertex * v1, * v2, * v3;
+  GtsEdge * e1, * e2;
+  gdouble o1, o2;
+  GtsFace * next;
+  GSList * constraint = NULL;
+
+  if (GTS_IS_CONSTRAINT (e))
+    constraint = g_slist_prepend (NULL, e);
+
+  gts_triangle_vertices_edges (GTS_TRIANGLE (f), e, 
+			       &v1, &v2, &v3, &e, &e1, &e2);
+  
+  o1 = gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), 
+			      GTS_POINT (s->v2));
+  o2 = gts_point_orientation (GTS_POINT (v3), GTS_POINT (v1), 
+			      GTS_POINT (s->v2));
+
+  if (o1 == 0. && o2 == 0.) {
+/*    if(o2 != 0.) {
+      fprintf(stderr, "o1 = %f o2 = %f\n", o1, o2);
+      fprintf(stderr, "v1 = %f, %f\n", GTS_POINT(v1)->x, GTS_POINT(v1)->y);
+      fprintf(stderr, "v2 = %f, %f\n", GTS_POINT(v2)->x, GTS_POINT(v2)->y);
+      fprintf(stderr, "v3 = %f, %f\n", GTS_POINT(v3)->x, GTS_POINT(v3)->y);
+      fprintf(stderr, "s->v2 = %f, %f\n", GTS_POINT(s->v2)->x, GTS_POINT(s->v2)->y);
+
+      g_assert (o2 == 0.);
+    }*/
+ //   if(o2 == 0.) {
+      remove_triangles (e, surface);
+      if (!constraint && !e->triangles)
+        gts_object_destroy (GTS_OBJECT (e));
+      *left = g_slist_prepend (*left, e2);
+      *right = g_slist_prepend (*right, e1);
+//    }
+  }
+  else if (o1 > 0.) {
+    g_assert (o2 <= 0.);
+    NEXT_CUT (e2, e1, right)
+  }
+  else if (o2 >= 0.)
+    NEXT_CUT (e1, e2, left)
+  else {
+    gdouble o3 = gts_point_orientation (GTS_POINT (s->v1), GTS_POINT (s->v2),
+					GTS_POINT (v3));
+    if (o3 > 0.)
+      NEXT_CUT (e1, e2, left)
+    else
+      NEXT_CUT (e2, e1, right)
+  }
+  return constraint;
+}
+
+static GSList * 
+remove_intersected_vertex (GtsSegment * s,
+			   GtsVertex * v,
+			   GtsSurface * surface,
+			   GSList ** left,
+			   GSList ** right,
+			   GtsFace ** ref)
+{
+  GSList * triangles = gts_vertex_triangles (v, NULL);
+  GSList * i;
+
+  i = triangles;
+  while (i) {
+    GtsTriangle * t = i->data;
+    if (GTS_IS_FACE (t) && 
+	gts_face_has_parent_surface (GTS_FACE (t), surface)) {
+      GtsVertex * v1, * v2, * v3;
+      gdouble o1, o2;
+
+      gts_triangle_vertices (t, &v1, &v2, &v3);
+      if (v == v2) {
+	v2 = v3;
+	v3 = v1;
+      }
+      else if (v == v3) {
+	v3 = v2;
+	v2 = v1;	
+      }
+      else
+	g_assert (v == v1);
+
+      if ((o1 = gts_point_orientation (GTS_POINT (v), GTS_POINT (v2),
+				       GTS_POINT (s->v2))) >= 0. &&
+	  (o2 = gts_point_orientation (GTS_POINT (v3), GTS_POINT (v),
+				       GTS_POINT (s->v2))) >= 0.) {
+	gdouble o3 = gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3),
+					    GTS_POINT (s->v2));
+	GtsEdge * e = gts_triangle_edge_opposite (t, v);
+	GtsEdge * e1, * e2;
+	GtsFace * next = neighbor (GTS_FACE (t), e, surface);
+
+	*ref = GTS_FACE (t);
+	gts_triangle_vertices_edges (t, e, &v2, &v3, &v, &e, &e2, &e1);
+
+	g_slist_free (triangles);
+
+	if (o3 >= 0.) /* @s->v2 is inside (or on the edge) of t */
+	  return NULL;
+
+	gts_allow_floating_faces = TRUE;
+	gts_surface_remove_face (surface, GTS_FACE (t));
+	gts_allow_floating_faces = FALSE;
+
+	*left = g_slist_prepend (*left, e2);
+	*right = g_slist_prepend (*right, e1);
+
+	g_assert (next);
+	return remove_intersected_edge (s, e, next, surface, left, right);
+      }
+    }
+    i = i->next;
+  }
+
+  g_assert_not_reached ();
+  return NULL;
+}
+
+/**
+ * gts_delaunay_add_constraint:
+ * @surface: a #GtsSurface.
+ * @c: a #GtsConstraint.
+ *
+ * Add constraint @c to the constrained Delaunay triangulation defined by
+ * @surface.
+ *
+ * Returns: a list of #GtsConstraint conflicting (i.e. intersecting) with @c 
+ * which were removed from @surface (%NULL if there was none).
+ */
+GSList * gts_delaunay_add_constraint (GtsSurface * surface,
+				      GtsConstraint * c)
+{
+  GSList * constraints;
+  GtsVertex * v1, * v2;
+  GSList * left = NULL, * right = NULL;
+  GtsFace * ref = NULL;
+
+  g_return_val_if_fail (surface != NULL, NULL);
+  g_return_val_if_fail (c != NULL, NULL);
+  g_return_val_if_fail (GTS_IS_CONSTRAINT (c), NULL);
+  
+  v1 = GTS_SEGMENT (c)->v1;
+  v2 = GTS_SEGMENT (c)->v2;
+  
+  gts_allow_floating_edges = TRUE;
+  constraints = remove_intersected_vertex (GTS_SEGMENT (c), v1, surface,
+					   &left, &right, &ref);
+  gts_allow_floating_edges = FALSE;
+#if 1
+  triangulate_polygon (g_slist_prepend (g_slist_reverse (right), c), 
+		       surface, ref);
+  triangulate_polygon (g_slist_prepend (left, c), 
+		       surface, ref);
+#else
+  right = g_slist_prepend (g_slist_reverse (right), c);
+  left = g_slist_prepend (left, c);
+  {
+    FILE * fp0 = fopen ("hole", "wt");
+    FILE * fp1 = fopen ("right", "wt");
+    FILE * fp2 = fopen ("left", "wt");
+    GSList * i = left;
+
+    gts_surface_write (surface, fp0);
+    fclose (fp0);
+ 
+    fprintf (fp2, "LIST {\n");
+    while (i) {
+      GtsSegment * s = i->data;
+      fprintf (fp2, 
+	       "# %p: %p->%p\n"
+	       "VECT 1 2 0 2 0 %g %g 0 %g %g 0\n",
+	       s, s->v1, s->v2,
+	       GTS_POINT (s->v1)->x, GTS_POINT (s->v1)->y,
+	       GTS_POINT (s->v2)->x, GTS_POINT (s->v2)->y);
+      i = i->next;
+    }
+    fprintf (fp2, "}\n");
+    fprintf (fp1, "LIST {\n");
+    i = right;
+    while (i) {
+      GtsSegment * s = i->data;
+      fprintf (fp1, 
+	       "# %p: %p->%p\n"
+	       "VECT 1 2 0 2 0 %g %g 0 %g %g 0\n",
+	       s, s->v1, s->v2,
+	       GTS_POINT (s->v1)->x, GTS_POINT (s->v1)->y,
+	       GTS_POINT (s->v2)->x, GTS_POINT (s->v2)->y);
+      i = i->next;
+    }
+    fprintf (fp1, "}\n");
+    fclose (fp1);
+    fclose (fp2);
+  }
+  triangulate_polygon (right, surface);
+  triangulate_polygon (left, surface);
+#endif
+  if (ref && !ref->surfaces) {
+    gts_allow_floating_edges = TRUE;
+    gts_object_destroy (GTS_OBJECT (ref));
+    gts_allow_floating_edges = FALSE;
+  }
+  return constraints;
+}
+
+static void delaunay_check (GtsTriangle * t, gpointer * data)
+{
+  GtsSurface * surface = data[0];
+  GtsFace ** face = data[1];
+
+  if (*face == NULL) {
+    GSList * i, * list;
+    GtsVertex * v1, * v2, * v3;
+
+    gts_triangle_vertices (t, &v1, &v2, &v3);
+    list = gts_vertex_neighbors (v1, NULL, surface);
+    list = gts_vertex_neighbors (v2, list, surface);
+    list = gts_vertex_neighbors (v3, list, surface);
+    i = list;
+    while (i && *face == NULL) {
+      GtsVertex * v = i->data;
+      if (v != v1 && v != v2 && v != v3 &&
+	  gts_point_in_circle (GTS_POINT (v), 
+			       GTS_POINT (v1),
+			       GTS_POINT (v2),  
+			       GTS_POINT (v3)) > 0.)
+	*face = GTS_FACE (t);
+      i = i->next;
+    }
+    g_slist_free (list);
+  }
+}
+
+/**
+ * gts_delaunay_check:
+ * @surface: a #GtsSurface.
+ *
+ * Returns: %NULL if the planar projection of @surface is a Delaunay 
+ * triangulation (unconstrained), a #GtsFace violating the Delaunay
+ * property otherwise.
+ */
+GtsFace * gts_delaunay_check (GtsSurface * surface)
+{
+  GtsFace * face = NULL;
+  gpointer data[2];
+
+  g_return_val_if_fail (surface != NULL, FALSE);
+
+  data[0] = surface;
+  data[1] = &face;
+  gts_surface_foreach_face (surface, (GtsFunc) delaunay_check, data);
+
+  return face;
+}
+
+/**
+ * gts_delaunay_remove_hull:
+ * @surface: a #GtsSurface.
+ *
+ * Removes all the edges of the boundary of @surface which are not
+ * constraints.  
+ */
+void gts_delaunay_remove_hull (GtsSurface * surface)
+{
+  GSList * boundary;
+
+  g_return_if_fail (surface != NULL);
+
+  boundary = gts_surface_boundary (surface);
+  gts_allow_floating_edges = TRUE;
+  while (boundary) {
+    GSList * i = boundary;
+    GtsEdge * e = i->data;
+
+    boundary = i->next;
+    g_slist_free_1 (i);
+    if (!GTS_IS_CONSTRAINT (e)) {
+      GtsTriangle * t = GTS_TRIANGLE (gts_edge_is_boundary (e, surface));
+
+      if (t != NULL) {
+	if (t->e1 != e && !GTS_IS_CONSTRAINT (t->e1) &&
+	    !gts_edge_is_boundary (t->e1, surface))
+	  boundary = g_slist_prepend (boundary, t->e1);
+	if (t->e2 != e && !GTS_IS_CONSTRAINT (t->e2) &&
+	    !gts_edge_is_boundary (t->e2, surface))
+	  boundary = g_slist_prepend (boundary, t->e2);
+	if (t->e3 != e && !GTS_IS_CONSTRAINT (t->e3) &&
+	    !gts_edge_is_boundary (t->e3, surface))
+	  boundary = g_slist_prepend (boundary, t->e3);
+	gts_surface_remove_face (surface, GTS_FACE (t));
+      }
+      if (!e->triangles)
+	gts_object_destroy (GTS_OBJECT (e));
+    }
+  }
+  gts_allow_floating_edges = FALSE;
+}
+
+/* GtsListFace: Object */
+
+static void gts_list_face_destroy (GtsObject * object)
+{
+  g_slist_free (GTS_LIST_FACE (object)->points);
+
+  (* GTS_OBJECT_CLASS (gts_list_face_class ())->parent_class->destroy) 
+    (object);
+}
+
+static void gts_list_face_class_init (GtsFaceClass * klass)
+{
+  GTS_OBJECT_CLASS (klass)->destroy = gts_list_face_destroy;
+}
+
+GtsFaceClass * gts_list_face_class (void)
+{
+  static GtsFaceClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo gts_list_face_info = {
+      "GtsListFace",
+      sizeof (GtsListFace),
+      sizeof (GtsFaceClass),
+      (GtsObjectClassInitFunc) gts_list_face_class_init,
+      (GtsObjectInitFunc) NULL,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_face_class ()),
+				  &gts_list_face_info);
+  }
+
+  return klass;
+}
diff --git a/gts/container.c b/gts/container.c
new file mode 100644
index 0000000..e1dc0fa
--- /dev/null
+++ b/gts/container.c
@@ -0,0 +1,493 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "gts.h"
+
+/* GtsContainee */
+
+static void containee_class_init (GtsContaineeClass * klass)
+{
+  klass->remove_container = NULL;
+  klass->add_container = NULL;
+  klass->foreach = NULL;
+  klass->is_contained = NULL;
+  klass->replace = NULL;
+}
+
+GtsContaineeClass * gts_containee_class (void)
+{
+  static GtsContaineeClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo containee_info = {
+      "GtsContainee",
+      sizeof (GtsContainee),
+      sizeof (GtsContaineeClass),
+      (GtsObjectClassInitFunc) containee_class_init,
+      (GtsObjectInitFunc) NULL,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (gts_object_class (),
+				  &containee_info);
+  }
+
+  return klass;
+}
+
+GtsContainee * gts_containee_new (GtsContaineeClass * klass)
+{
+  GtsContainee * object;
+
+  object = GTS_CONTAINEE (gts_object_new (GTS_OBJECT_CLASS (klass)));
+
+  return object;
+}
+
+gboolean gts_containee_is_contained (GtsContainee * item,
+				     GtsContainer * c)
+{
+  g_return_val_if_fail (item != NULL, FALSE);
+  g_return_val_if_fail (c != NULL, FALSE);
+
+  if (GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->is_contained)
+    return
+      (* GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->is_contained) 
+      (item, c);
+  return FALSE;
+}
+
+void gts_containee_replace (GtsContainee * item,
+			    GtsContainee * with)
+{
+  if (GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->replace)
+    (* GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->replace) (item, with);
+  if (GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->foreach) {
+    (* GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->foreach) 
+      (item, (GtsFunc) gts_container_add, with);
+    (* GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->foreach) 
+      (item, (GtsFunc) gts_container_remove, item);
+  }
+}
+
+/* GtsSListContainee */
+
+static void slist_containee_destroy (GtsObject * object)
+{
+  GtsSListContainee * item = GTS_SLIST_CONTAINEE (object);
+  GSList * i;
+
+  i = item->containers;
+  while (i) {
+    GSList * next = i->next;
+
+    gts_container_remove (i->data, GTS_CONTAINEE (item));
+    i = next;
+  }
+  g_assert (item->containers == NULL);
+
+  (* GTS_OBJECT_CLASS (gts_slist_containee_class ())->parent_class->destroy) 
+    (object);
+}
+
+static void slist_containee_remove_container (GtsContainee * i, 
+					      GtsContainer * c)
+{
+  GtsSListContainee * item = GTS_SLIST_CONTAINEE (i);
+  item->containers = g_slist_remove (item->containers, c);
+}
+
+static void slist_containee_add_container (GtsContainee * i, 
+					   GtsContainer * c)
+{
+  GtsSListContainee * item = GTS_SLIST_CONTAINEE (i);
+  if (!g_slist_find (item->containers, c))
+    item->containers = g_slist_prepend (item->containers, c);
+}
+
+static void slist_containee_foreach (GtsContainee * c,
+				     GtsFunc func, 
+				     gpointer data)
+{
+  GSList * i = GTS_SLIST_CONTAINEE (c)->containers;
+
+  while (i) {
+    GSList * next = i->next;
+    
+    (* func) (i->data, data);
+    i = next;
+  }
+}
+
+static gboolean slist_containee_is_contained (GtsContainee * i,
+					      GtsContainer * c)
+{
+  return g_slist_find (GTS_SLIST_CONTAINEE (i)->containers, c) ? TRUE : FALSE;
+}
+
+static void slist_containee_class_init (GtsSListContaineeClass * klass)
+{
+  GTS_CONTAINEE_CLASS (klass)->remove_container = 
+    slist_containee_remove_container;
+  GTS_CONTAINEE_CLASS (klass)->add_container = 
+    slist_containee_add_container;
+  GTS_CONTAINEE_CLASS (klass)->foreach = 
+    slist_containee_foreach;
+  GTS_CONTAINEE_CLASS (klass)->is_contained = 
+    slist_containee_is_contained;
+
+  GTS_OBJECT_CLASS (klass)->destroy = slist_containee_destroy;
+}
+
+static void slist_containee_init (GtsSListContainee * object)
+{
+  object->containers = NULL;
+}
+
+GtsSListContaineeClass * gts_slist_containee_class (void)
+{
+  static GtsSListContaineeClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo slist_containee_info = {
+      "GtsSListContainee",
+      sizeof (GtsSListContainee),
+      sizeof (GtsSListContaineeClass),
+      (GtsObjectClassInitFunc) slist_containee_class_init,
+      (GtsObjectInitFunc) slist_containee_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_containee_class ()),
+				  &slist_containee_info);
+  }
+
+  return klass;
+}
+
+/* GtsContainer */
+
+static void remove_container (GtsContainee * item, GtsContainer * c)
+{
+  if (GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->remove_container)
+    (* GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->remove_container) 
+      (item, c);
+}
+
+static void container_destroy (GtsObject * object)
+{
+  GtsContainer * c = GTS_CONTAINER (object);
+
+  gts_container_foreach (c, (GtsFunc) remove_container, c);
+
+  (* GTS_OBJECT_CLASS (gts_container_class ())->parent_class->destroy) 
+    (object);
+}
+
+static void container_add (GtsContainer * c, GtsContainee * item)
+{
+  if (GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->add_container)
+    (* GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->add_container)
+      (item, c);
+}
+
+static void container_remove (GtsContainer * c, GtsContainee * item)
+{
+  if (GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->remove_container)
+    (* GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->remove_container)
+      (item, c);
+}
+
+static void container_clone_add (GtsContainee * item, GtsContainer * clone)
+{
+  gts_container_add (clone, item);
+}
+
+static void container_clone (GtsObject * clone, GtsObject * object)
+{
+  gts_object_init (clone, object->klass);
+  gts_container_foreach (GTS_CONTAINER (object), 
+			 (GtsFunc) container_clone_add, clone);
+}
+
+static void container_class_init (GtsContainerClass * klass)
+{
+  klass->add = container_add;
+  klass->remove = container_remove;
+  klass->foreach = NULL;
+  klass->size = NULL;
+
+  GTS_OBJECT_CLASS (klass)->destroy = container_destroy;
+  GTS_OBJECT_CLASS (klass)->clone = container_clone;
+}
+
+GtsContainerClass * gts_container_class (void)
+{
+  static GtsContainerClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo container_info = {
+      "GtsContainer",
+      sizeof (GtsContainer),
+      sizeof (GtsContainerClass),
+      (GtsObjectClassInitFunc) container_class_init,
+      (GtsObjectInitFunc) NULL,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = 
+      gts_object_class_new (GTS_OBJECT_CLASS (gts_slist_containee_class ()), 
+			    &container_info);
+  }
+
+  return klass;
+}
+
+GtsContainer * gts_container_new (GtsContainerClass * klass)
+{
+  GtsContainer * object;
+
+  object = GTS_CONTAINER (gts_object_new (GTS_OBJECT_CLASS (klass)));
+
+  return object;
+}
+
+void gts_container_add (GtsContainer * c,
+			GtsContainee * item)
+{
+  g_return_if_fail (c != NULL);
+  g_return_if_fail (item != NULL);
+
+  g_assert (GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->add);
+  (* GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->add) (c, item);
+}
+
+void gts_container_remove (GtsContainer * c,
+			   GtsContainee * item)
+{
+  g_return_if_fail (c != NULL);
+  g_return_if_fail (item != NULL);
+
+  g_assert (GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->remove);
+  (* GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->remove) (c, item);
+}
+
+void gts_container_foreach (GtsContainer * c,
+			    GtsFunc func,
+			    gpointer data)
+{
+  g_return_if_fail (c != NULL);
+  g_return_if_fail (func != NULL);
+
+  if (GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->foreach)
+    (* GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->foreach) (c, func, data);
+}
+
+guint gts_container_size (GtsContainer * c)
+{
+  g_return_val_if_fail (c != NULL, 0);
+
+  if (GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->size)
+    return (* GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->size) (c);
+  return 0;
+}
+
+/* GtsHashContainer */
+
+static void hash_container_destroy (GtsObject * object)
+{
+  GHashTable * items = GTS_HASH_CONTAINER (object)->items;
+
+  (* GTS_OBJECT_CLASS (gts_hash_container_class ())->parent_class->destroy) 
+    (object);
+
+  g_hash_table_destroy (items);
+}
+
+static void hash_container_add (GtsContainer * c, GtsContainee * item)
+{
+  g_return_if_fail (GTS_HASH_CONTAINER (c)->frozen == FALSE);
+
+  g_hash_table_insert (GTS_HASH_CONTAINER (c)->items, item, NULL);
+
+  (* GTS_CONTAINER_CLASS (GTS_OBJECT_CLASS (gts_hash_container_class ())->parent_class)->add) (c, item);
+}
+
+static void hash_container_remove (GtsContainer * c, GtsContainee * item)
+{
+  g_return_if_fail (GTS_HASH_CONTAINER (c)->frozen == FALSE);
+
+  g_hash_table_remove (GTS_HASH_CONTAINER (c)->items, item);
+
+  (* GTS_CONTAINER_CLASS (GTS_OBJECT_CLASS (gts_hash_container_class ())->parent_class)->remove) (c, item);
+}
+
+static void hash_foreach (GtsContainee * item, 
+			  gpointer item_data, 
+			  gpointer * info)
+{
+  (* ((GtsFunc) info[0])) (item, info[1]);
+}
+
+static void hash_container_foreach (GtsContainer * c, 
+				    GtsFunc func, 
+				    gpointer data)
+{
+  gpointer info[2];
+  
+  info[0] = func;
+  info[1] = data;
+  /* prevent removing or adding items */
+  GTS_HASH_CONTAINER (c)->frozen = TRUE;
+  g_hash_table_foreach (GTS_HASH_CONTAINER (c)->items, 
+			(GHFunc) hash_foreach, info);
+  GTS_HASH_CONTAINER (c)->frozen = FALSE;
+}
+
+static guint hash_container_size (GtsContainer * c)
+{
+  return g_hash_table_size (GTS_HASH_CONTAINER (c)->items);
+}
+
+static void hash_container_class_init (GtsHashContainerClass * klass)
+{
+  GTS_CONTAINER_CLASS (klass)->add = hash_container_add;
+  GTS_CONTAINER_CLASS (klass)->remove = hash_container_remove;
+  GTS_CONTAINER_CLASS (klass)->foreach = hash_container_foreach;
+  GTS_CONTAINER_CLASS (klass)->size = hash_container_size;
+
+  GTS_OBJECT_CLASS (klass)->destroy = hash_container_destroy;
+}
+
+static void hash_container_init (GtsHashContainer * object)
+{
+  object->items = g_hash_table_new (NULL, NULL);
+  object->frozen = FALSE;
+}
+
+GtsHashContainerClass * gts_hash_container_class (void)
+{
+  static GtsHashContainerClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo hash_container_info = {
+      "GtsHashContainer",
+      sizeof (GtsHashContainer),
+      sizeof (GtsHashContainerClass),
+      (GtsObjectClassInitFunc) hash_container_class_init,
+      (GtsObjectInitFunc) hash_container_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_container_class ()),
+				  &hash_container_info);
+  }
+
+  return klass;
+}
+
+/* GtsSListContainer */
+
+static void slist_container_destroy (GtsObject * object)
+{
+  GSList * items = GTS_SLIST_CONTAINER (object)->items;
+
+  (* GTS_OBJECT_CLASS (gts_slist_container_class ())->parent_class->destroy) 
+    (object);
+
+  g_slist_free (items);
+}
+
+static void slist_container_add (GtsContainer * c, GtsContainee * item)
+{
+  g_return_if_fail (GTS_SLIST_CONTAINER (c)->frozen == FALSE);
+
+  if (!g_slist_find (GTS_SLIST_CONTAINER (c)->items, item))
+    GTS_SLIST_CONTAINER (c)->items = 
+      g_slist_prepend (GTS_SLIST_CONTAINER (c)->items, item);
+
+  (* GTS_CONTAINER_CLASS (GTS_OBJECT_CLASS (gts_slist_container_class ())->parent_class)->add) (c, item);
+}
+
+static void slist_container_remove (GtsContainer * c, GtsContainee * item)
+{
+  g_return_if_fail (GTS_SLIST_CONTAINER (c)->frozen == FALSE);
+
+  GTS_SLIST_CONTAINER (c)->items = 
+      g_slist_remove (GTS_SLIST_CONTAINER (c)->items, item);
+
+  (* GTS_CONTAINER_CLASS (GTS_OBJECT_CLASS (gts_slist_container_class ())->parent_class)->remove) (c, item);
+}
+
+static void slist_container_foreach (GtsContainer * c, 
+				     GtsFunc func, 
+				     gpointer data)
+{
+  GSList * i;
+
+  i = GTS_SLIST_CONTAINER (c)->items;
+  while (i) {
+    GSList * next = i->next;
+
+    (* func) (i->data, data);
+    i = next;
+  }
+}
+
+static guint slist_container_size (GtsContainer * c)
+{
+  return g_slist_length (GTS_SLIST_CONTAINER (c)->items);
+}
+
+static void slist_container_class_init (GtsSListContainerClass * klass)
+{
+  GTS_CONTAINER_CLASS (klass)->add = slist_container_add;
+  GTS_CONTAINER_CLASS (klass)->remove = slist_container_remove;
+  GTS_CONTAINER_CLASS (klass)->foreach = slist_container_foreach;
+  GTS_CONTAINER_CLASS (klass)->size = slist_container_size;
+
+  GTS_OBJECT_CLASS (klass)->destroy = slist_container_destroy;
+}
+
+static void slist_container_init (GtsSListContainer * object)
+{
+  object->items = NULL;
+  object->frozen = FALSE;
+}
+
+GtsSListContainerClass * gts_slist_container_class (void)
+{
+  static GtsSListContainerClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo slist_container_info = {
+      "GtsSListContainer",
+      sizeof (GtsSListContainer),
+      sizeof (GtsSListContainerClass),
+      (GtsObjectClassInitFunc) slist_container_class_init,
+      (GtsObjectInitFunc) slist_container_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_container_class ()),
+				  &slist_container_info);
+  }
+
+  return klass;
+}
diff --git a/gts/curvature.c b/gts/curvature.c
new file mode 100644
index 0000000..70f6af2
--- /dev/null
+++ b/gts/curvature.c
@@ -0,0 +1,621 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999-2002 Ray Jones, Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <math.h>
+#include "gts.h"
+
+static gboolean angle_obtuse (GtsVertex * v, GtsFace * f)
+{
+  GtsEdge * e = gts_triangle_edge_opposite (GTS_TRIANGLE (f), v);
+  GtsVector vec1, vec2;
+
+  gts_vector_init (vec1, GTS_POINT (v), GTS_POINT (GTS_SEGMENT (e)->v1));
+  gts_vector_init (vec2, GTS_POINT (v), GTS_POINT (GTS_SEGMENT (e)->v2));
+
+  return (gts_vector_scalar (vec1, vec2) < 0.0);
+}
+
+static gboolean triangle_obtuse (GtsVertex * v, GtsFace * f)
+{
+  GtsEdge * e = gts_triangle_edge_opposite (GTS_TRIANGLE (f), v);
+
+  return (angle_obtuse (v, f) ||
+          angle_obtuse (GTS_SEGMENT (e)->v1, f) ||
+          angle_obtuse (GTS_SEGMENT (e)->v2, f));
+} 
+
+static gdouble cotan (GtsVertex * vo, GtsVertex * v1, GtsVertex * v2)
+{
+  /* cf. Appendix B of [Meyer et al 2002] */
+  GtsVector u, v;
+  gdouble udotv, denom;
+
+  gts_vector_init (u, GTS_POINT (vo), GTS_POINT (v1));
+  gts_vector_init (v, GTS_POINT (vo), GTS_POINT (v2));
+
+  udotv = gts_vector_scalar (u, v);
+  denom = sqrt (gts_vector_scalar (u,u)*gts_vector_scalar (v,v) -
+		udotv*udotv);
+
+
+  /* denom can be zero if u==v.  Returning 0 is acceptable, based on
+   * the callers of this function below. */
+  if (denom == 0.0) return (0.0);
+
+  return (udotv/denom);
+}
+
+static gdouble angle_from_cotan (GtsVertex * vo, 
+				 GtsVertex * v1, GtsVertex * v2)
+{
+  /* cf. Appendix B and the caption of Table 1 from [Meyer et al 2002] */
+  GtsVector u, v;
+  gdouble udotv, denom;
+
+  gts_vector_init (u, GTS_POINT (vo), GTS_POINT (v1));
+  gts_vector_init (v, GTS_POINT (vo), GTS_POINT (v2));
+
+  udotv = gts_vector_scalar (u, v);
+  denom = sqrt (gts_vector_scalar (u,u)*gts_vector_scalar (v,v) 
+		- udotv*udotv);
+
+  /* Note: I assume this is what they mean by using atan2 (). -Ray Jones */
+
+  /* tan = denom/udotv = y/x (see man page for atan2) */
+  return (fabs (atan2 (denom, udotv)));
+}
+
+static gdouble region_area (GtsVertex * v, GtsFace * f)
+{
+  /* cf. Section 3.3 of [Meyer et al 2002] */
+  
+  if (gts_triangle_area (GTS_TRIANGLE (f)) == 0.0) return (0.0);
+
+  if (triangle_obtuse (v, f)) {
+    if (angle_obtuse (v, f))
+      return (gts_triangle_area (GTS_TRIANGLE (f))/2.0);
+    else
+      return (gts_triangle_area (GTS_TRIANGLE (f))/4.0);
+  } else {
+    GtsEdge * e = gts_triangle_edge_opposite (GTS_TRIANGLE (f), v);
+
+    return ((cotan (GTS_SEGMENT (e)->v1, v, GTS_SEGMENT (e)->v2)* 
+             gts_point_distance2 (GTS_POINT (v), 
+				  GTS_POINT (GTS_SEGMENT (e)->v2)) +
+             cotan (GTS_SEGMENT (e)->v2, v, GTS_SEGMENT (e)->v1)* 
+             gts_point_distance2 (GTS_POINT (v), 
+                                  GTS_POINT (GTS_SEGMENT (e)->v1)))
+            /8.0);
+  }
+}
+
+/** 
+ * gts_vertex_mean_curvature_normal:
+ * @v: a #GtsVertex.  
+ * @s: a #GtsSurface.
+ * @Kh: the Mean Curvature Normal at @v.
+ *
+ * Computes the Discrete Mean Curvature Normal approximation at @v.
+ * The mean curvature at @v is half the magnitude of the vector @Kh.
+ *
+ * Note: the normal computed is not unit length, and may point either
+ * into or out of the surface, depending on the curvature at @v.  It
+ * is the responsibility of the caller of the function to use the mean
+ * curvature normal appropriately.
+ *
+ * This approximation is from the paper:
+ * Discrete Differential-Geometry Operators for Triangulated 2-Manifolds
+ * Mark Meyer, Mathieu Desbrun, Peter Schroder, Alan H. Barr
+ * VisMath '02, Berlin (Germany) 
+ * http://www-grail.usc.edu/pubs.html
+ *
+ * Returns: %TRUE if the operator could be evaluated, %FALSE if the
+ * evaluation failed for some reason (@v is boundary or is the
+ * endpoint of a non-manifold edge.)
+ */
+gboolean gts_vertex_mean_curvature_normal (GtsVertex * v, GtsSurface * s, 
+                                           GtsVector Kh)
+{
+  GSList * faces, * edges, * i;
+  gdouble area = 0.0;
+
+  g_return_val_if_fail (v != NULL, FALSE);
+  g_return_val_if_fail (s != NULL, FALSE);
+
+  /* this operator is not defined for boundary edges */
+  if (gts_vertex_is_boundary (v, s)) return (FALSE);
+    
+  faces = gts_vertex_faces (v, s, NULL);
+  g_return_val_if_fail (faces != NULL, FALSE);
+
+  edges = gts_vertex_fan_oriented (v, s);
+  if (edges == NULL) {
+    g_slist_free (faces);
+    return (FALSE);
+  }
+
+  i = faces;
+  while (i) {
+    GtsFace * f = i->data;
+
+    area += region_area (v, f);
+    i = i->next;
+  } 
+  g_slist_free (faces);
+
+  Kh[0] = Kh[1] = Kh[2] = 0.0;
+
+  i = edges;
+  while (i) {
+    GtsEdge * e = i->data;
+    GtsVertex * v1 = GTS_SEGMENT (e)->v1;
+    GtsVertex * v2 = GTS_SEGMENT (e)->v2;
+    gdouble temp;
+
+    temp = cotan (v1, v, v2);
+    Kh[0] += temp*(GTS_POINT (v2)->x - GTS_POINT (v)->x);
+    Kh[1] += temp*(GTS_POINT (v2)->y - GTS_POINT (v)->y);
+    Kh[2] += temp*(GTS_POINT (v2)->z - GTS_POINT (v)->z);
+
+    temp = cotan (v2, v, v1);
+    Kh[0] += temp*(GTS_POINT (v1)->x - GTS_POINT (v)->x);
+    Kh[1] += temp*(GTS_POINT (v1)->y - GTS_POINT (v)->y);
+    Kh[2] += temp*(GTS_POINT (v1)->z - GTS_POINT (v)->z);
+
+    i = i->next;
+  }
+  g_slist_free (edges);
+
+  if (area > 0.0) {
+    Kh[0] /= 2*area;
+    Kh[1] /= 2*area;
+    Kh[2] /= 2*area;
+  } else {
+    return (FALSE);
+  }
+ 
+  return TRUE;
+}
+
+/** 
+ * gts_vertex_gaussian_curvature:
+ * @v: a #GtsVertex.  
+ * @s: a #GtsSurface.
+ * @Kg: the Discrete Gaussian Curvature approximation at @v.
+ *
+ * Computes the Discrete Gaussian Curvature approximation at @v.
+ *
+ * This approximation is from the paper:
+ * Discrete Differential-Geometry Operators for Triangulated 2-Manifolds
+ * Mark Meyer, Mathieu Desbrun, Peter Schroder, Alan H. Barr
+ * VisMath '02, Berlin (Germany) 
+ * http://www-grail.usc.edu/pubs.html
+ *
+ * Returns: %TRUE if the operator could be evaluated, %FALSE if the
+ * evaluation failed for some reason (@v is boundary or is the
+ * endpoint of a non-manifold edge.)
+ */
+gboolean gts_vertex_gaussian_curvature (GtsVertex * v, GtsSurface * s, 
+                                        gdouble * Kg)
+{
+  GSList * faces, * edges, * i;
+  gdouble area = 0.0;
+  gdouble angle_sum = 0.0;
+
+  g_return_val_if_fail (v != NULL, FALSE);
+  g_return_val_if_fail (s != NULL, FALSE);
+  g_return_val_if_fail (Kg != NULL, FALSE);
+
+  /* this operator is not defined for boundary edges */
+  if (gts_vertex_is_boundary (v, s)) return (FALSE);
+    
+  faces = gts_vertex_faces (v, s, NULL);
+  g_return_val_if_fail (faces != NULL, FALSE);
+
+  edges = gts_vertex_fan_oriented (v, s);
+  if (edges == NULL) {
+    g_slist_free (faces);
+    return (FALSE);
+  }
+
+  i = faces;
+  while (i) {
+    GtsFace * f = i->data;
+
+    area += region_area (v, f);
+    i = i->next;
+  } 
+  g_slist_free (faces);
+
+  i = edges;
+  while (i) {
+    GtsEdge * e = i->data;
+    GtsVertex * v1 = GTS_SEGMENT (e)->v1;
+    GtsVertex * v2 = GTS_SEGMENT (e)->v2;
+
+    angle_sum += angle_from_cotan (v, v1, v2);
+    i = i->next;
+  }
+  g_slist_free (edges);
+
+  *Kg = (2.0*M_PI - angle_sum)/area;
+ 
+  return TRUE;
+}
+
+/** 
+ * gts_vertex_principal_curvatures:
+ * @Kh: mean curvature.
+ * @Kg: Gaussian curvature.
+ * @K1: first principal curvature.
+ * @K2: second principal curvature.
+ *
+ * Computes the principal curvatures at a point given the mean and
+ * Gaussian curvatures at that point.  
+ *
+ * The mean curvature can be computed as one-half the magnitude of the
+ * vector computed by gts_vertex_mean_curvature_normal().
+ *
+ * The Gaussian curvature can be computed with
+ * gts_vertex_gaussian_curvature().
+ */
+void gts_vertex_principal_curvatures (gdouble Kh, gdouble Kg, 
+				      gdouble * K1, gdouble * K2)
+{
+  gdouble temp = Kh*Kh - Kg;
+
+  g_return_if_fail (K1 != NULL);
+  g_return_if_fail (K2 != NULL);
+
+  if (temp < 0.0) temp = 0.0;
+  temp = sqrt (temp);
+  *K1 = Kh + temp;
+  *K2 = Kh - temp;
+}
+
+/* from Maple */
+static void linsolve (gdouble m11, gdouble m12, gdouble b1,
+		      gdouble m21, gdouble m22, gdouble b2,
+		      gdouble * x1, gdouble * x2)
+{
+  gdouble temp;
+
+  temp = 1.0 / (m21*m12 - m11*m22);
+  *x1 = (m12*b2 - m22*b1)*temp;
+  *x2 = (m11*b2 - m21*b1)*temp;
+}
+                
+/* from Maple - largest eigenvector of [a b; b c] */
+static void eigenvector (gdouble a, gdouble b, gdouble c,
+			 GtsVector e)
+{
+  if (b == 0.0) {
+    e[0] = 0.0;
+  } else {
+    e[0] = -(c - a - sqrt (c*c - 2*a*c + a*a + 4*b*b))/(2*b);
+  }
+  e[1] = 1.0;
+  e[2] = 0.0;
+}
+
+/** 
+ * gts_vertex_principal_directions:
+ * @v: a #GtsVertex.  
+ * @s: a #GtsSurface.
+ * @Kh: mean curvature normal (a #GtsVector).
+ * @Kg: Gaussian curvature (a gdouble).
+ * @e1: first principal curvature direction (direction of largest curvature).
+ * @e2: second principal curvature direction.
+ *
+ * Computes the principal curvature directions at a point given @Kh
+ * and @Kg, the mean curvature normal and Gaussian curvatures at that
+ * point, computed with gts_vertex_mean_curvature_normal() and
+ * gts_vertex_gaussian_curvature(), respectively. 
+ *
+ * Note that this computation is very approximate and tends to be
+ * unstable.  Smoothing of the surface or the principal directions may
+ * be necessary to achieve reasonable results.  
+ */
+void gts_vertex_principal_directions (GtsVertex * v, GtsSurface * s,
+                                      GtsVector Kh, gdouble Kg,
+				      GtsVector e1, GtsVector e2)
+{
+  GtsVector N;
+  gdouble normKh;
+  GSList * i, * j;
+  GtsVector basis1, basis2, d, eig;
+  gdouble ve2, vdotN;
+  gdouble aterm_da, bterm_da, cterm_da, const_da;
+  gdouble aterm_db, bterm_db, cterm_db, const_db;
+  gdouble a, b, c;
+  gdouble K1, K2;
+  gdouble *weights, *kappas, *d1s, *d2s;
+  gint edge_count;
+  gdouble err_e1, err_e2;
+  int e;
+
+  /* compute unit normal */
+  normKh = sqrt (gts_vector_scalar (Kh, Kh));
+
+  if (normKh > 0.0) {
+    N[0] = Kh[0] / normKh;
+    N[1] = Kh[1] / normKh;
+    N[2] = Kh[2] / normKh;
+  } else {
+    /* This vertex is a point of zero mean curvature (flat or saddle
+     * point).  Compute a normal by averaging the adjacent triangles
+     */
+    N[0] = N[1] = N[2] = 0.0;
+    i = gts_vertex_faces (v, s, NULL);
+    while (i) {
+      gdouble x, y, z;
+      gts_triangle_normal (GTS_TRIANGLE ((GtsFace *) i->data),
+                           &x, &y, &z);
+      N[0] += x;
+      N[1] += y;
+      N[2] += z;
+
+      i = i->next;
+    }
+    g_return_if_fail (gts_vector_norm (N) > 0.0);
+    gts_vector_normalize (N);
+  }
+    
+
+  /* construct a basis from N: */
+  /* set basis1 to any component not the largest of N */
+  basis1[0] =  basis1[1] =  basis1[2] = 0.0;
+  if (fabs (N[0]) > fabs (N[1]))
+    basis1[1] = 1.0;
+  else
+    basis1[0] = 1.0;
+    
+  /* make basis2 orthogonal to N */
+  gts_vector_cross (basis2, N, basis1);
+  gts_vector_normalize (basis2);
+
+  /* make basis1 orthogonal to N and basis2 */
+  gts_vector_cross (basis1, N, basis2);
+  gts_vector_normalize (basis1);
+  
+  aterm_da = bterm_da = cterm_da = const_da = 0.0;
+  aterm_db = bterm_db = cterm_db = const_db = 0.0;
+
+  weights = g_malloc (sizeof (gdouble)*g_slist_length (v->segments));
+  kappas = g_malloc (sizeof (gdouble)*g_slist_length (v->segments));
+  d1s = g_malloc (sizeof (gdouble)*g_slist_length (v->segments));
+  d2s = g_malloc (sizeof (gdouble)*g_slist_length (v->segments));
+  edge_count = 0;
+
+  i = v->segments;
+  while (i) {
+    GtsEdge * e;
+    GtsFace * f1, * f2;
+    gdouble weight, kappa, d1, d2;
+    GtsVector vec_edge;
+
+    if (! GTS_IS_EDGE (i->data)) {
+      i = i->next;
+      continue;
+    }
+
+    e = i->data;
+
+    /* since this vertex passed the tests in
+     * gts_vertex_mean_curvature_normal(), this should be true. */
+    g_assert (gts_edge_face_number (e, s) == 2);
+
+    /* identify the two triangles bordering e in s */
+    f1 = f2 = NULL;
+    j = e->triangles;
+    while (j) {
+      if ((! GTS_IS_FACE (j->data)) || 
+          (! gts_face_has_parent_surface (GTS_FACE (j->data), s))) {
+        j = j->next;
+        continue;
+      }
+      if (f1 == NULL)
+        f1 = GTS_FACE (j->data);
+      else {
+        f2 = GTS_FACE (j->data);
+        break;
+      }
+      j = j->next;
+    }
+    g_assert (f2 != NULL);
+
+    /* We are solving for the values of the curvature tensor 
+     *     B = [ a b ; b c ].  
+     * The computations here are from section 5 of [Meyer et al 2002].  
+     *
+     * The first step is to calculate the linear equations governing
+     * the values of (a,b,c).  These can be computed by setting the
+     * derivatives of the error E to zero (section 5.3).
+     * 
+     * Since a + c = norm(Kh), we only compute the linear equations
+     * for dE/da and dE/db.  (NB: [Meyer et al 2002] has the
+     * equation a + b = norm(Kh), but I'm almost positive this is
+     * incorrect.)
+     *
+     * Note that the w_ij (defined in section 5.2) are all scaled by
+     * (1/8*A_mixed).  We drop this uniform scale factor because the
+     * solution of the linear equations doesn't rely on it.
+     *
+     * The terms of the linear equations are xterm_dy with x in
+     * {a,b,c} and y in {a,b}.  There are also const_dy terms that are
+     * the constant factors in the equations.  
+     */
+
+    /* find the vector from v along edge e */
+    gts_vector_init (vec_edge, GTS_POINT (v), 
+                     GTS_POINT ((GTS_SEGMENT (e)->v1 == v) ? 
+                                GTS_SEGMENT (e)->v2 : GTS_SEGMENT (e)->v1));
+    ve2 = gts_vector_scalar (vec_edge, vec_edge);
+    vdotN = gts_vector_scalar (vec_edge, N);
+
+    /* section 5.2 - There is a typo in the computation of kappa.  The
+     * edges should be x_j-x_i.
+     */
+    kappa = 2.0 * vdotN / ve2;
+
+    /* section 5.2 */
+
+    /* I don't like performing a minimization where some of the
+     * weights can be negative (as can be the case if f1 or f2 are
+     * obtuse).  To ensure all-positive weights, we check for
+     * obtuseness and use values similar to those in region_area(). */
+    weight = 0.0;
+    if (! triangle_obtuse(v, f1)) {
+      weight += ve2 * 
+        cotan (gts_triangle_vertex_opposite (GTS_TRIANGLE (f1), e), 
+               GTS_SEGMENT (e)->v1, GTS_SEGMENT (e)->v2) / 8.0;
+    } else {
+      if (angle_obtuse (v, f1)) {
+        weight += ve2 * gts_triangle_area (GTS_TRIANGLE (f1)) / 4.0;
+      } else {
+        weight += ve2 * gts_triangle_area (GTS_TRIANGLE (f1)) / 8.0;
+      }
+    }
+
+    if (! triangle_obtuse(v, f2)) {
+      weight += ve2 * 
+        cotan (gts_triangle_vertex_opposite (GTS_TRIANGLE (f2), e), 
+               GTS_SEGMENT (e)->v1, GTS_SEGMENT (e)->v2) / 8.0;
+    } else {
+      if (angle_obtuse (v, f2)) {
+        weight += ve2 * gts_triangle_area (GTS_TRIANGLE (f2)) / 4.0;
+      } else {
+        weight += ve2 * gts_triangle_area (GTS_TRIANGLE (f2)) / 8.0;
+      }
+    }
+
+    /* projection of edge perpendicular to N (section 5.3) */
+    d[0] = vec_edge[0] - vdotN * N[0];
+    d[1] = vec_edge[1] - vdotN * N[1];
+    d[2] = vec_edge[2] - vdotN * N[2];
+    gts_vector_normalize (d);
+    
+    /* not explicit in the paper, but necessary.  Move d to 2D basis. */
+    d1 = gts_vector_scalar (d, basis1);
+    d2 = gts_vector_scalar (d, basis2);
+
+    /* store off the curvature, direction of edge, and weights for later use */
+    weights[edge_count] = weight;
+    kappas[edge_count] = kappa;
+    d1s[edge_count] = d1;
+    d2s[edge_count] = d2;
+    edge_count++;
+
+    /* Finally, update the linear equations */
+    aterm_da += weight * d1 * d1 * d1 * d1;
+    bterm_da += weight * d1 * d1 * 2 * d1 * d2;
+    cterm_da += weight * d1 * d1 * d2 * d2;
+    const_da += weight * d1 * d1 * (- kappa);
+
+    aterm_db += weight * d1 * d2 * d1 * d1;
+    bterm_db += weight * d1 * d2 * 2 * d1 * d2;
+    cterm_db += weight * d1 * d2 * d2 * d2;
+    const_db += weight * d1 * d2 * (- kappa);
+
+    i = i->next;
+  }
+
+  /* now use the identity (Section 5.3) a + c = |Kh| = 2 * kappa_h */
+  aterm_da -= cterm_da;
+  const_da += cterm_da * normKh;
+
+  aterm_db -= cterm_db;
+  const_db += cterm_db * normKh;
+  
+  /* check for solvability of the linear system */
+  if (((aterm_da * bterm_db - aterm_db * bterm_da) != 0.0) &&
+      ((const_da != 0.0) || (const_db != 0.0))) {
+    linsolve (aterm_da, bterm_da, -const_da,
+              aterm_db, bterm_db, -const_db,
+              &a, &b);
+
+    c = normKh - a;
+
+    eigenvector (a, b, c, eig);
+  } else {
+    /* region of v is planar */
+    eig[0] = 1.0;
+    eig[1] = 0.0;
+  }
+
+  /* Although the eigenvectors of B are good estimates of the
+   * principal directions, it seems that which one is attached to
+   * which curvature direction is a bit arbitrary.  This may be a bug
+   * in my implementation, or just a side-effect of the inaccuracy of
+   * B due to the discrete nature of the sampling.
+   *
+   * To overcome this behavior, we'll evaluate which assignment best
+   * matches the given eigenvectors by comparing the curvature
+   * estimates computed above and the curvatures calculated from the
+   * discrete differential operators.  */
+
+  gts_vertex_principal_curvatures (0.5 * normKh, Kg, &K1, &K2);
+  
+  err_e1 = err_e2 = 0.0;
+  /* loop through the values previously saved */
+  for (e = 0; e < edge_count; e++) {
+    gdouble weight, kappa, d1, d2;
+    gdouble temp1, temp2;
+    gdouble delta;
+
+    weight = weights[e];
+    kappa = kappas[e];
+    d1 = d1s[e];
+    d2 = d2s[e];
+
+    temp1 = fabs (eig[0] * d1 + eig[1] * d2);
+    temp1 = temp1 * temp1;
+    temp2 = fabs (eig[1] * d1 - eig[0] * d2);
+    temp2 = temp2 * temp2;
+
+    /* err_e1 is for K1 associated with e1 */
+    delta = K1 * temp1 + K2 * temp2 - kappa;
+    err_e1 += weight * delta * delta;
+
+    /* err_e2 is for K1 associated with e2 */
+    delta = K2 * temp1 + K1 * temp2 - kappa;
+    err_e2 += weight * delta * delta;
+  }
+  g_free (weights);
+  g_free (kappas);
+  g_free (d1s);
+  g_free (d2s);
+
+  /* rotate eig by a right angle if that would decrease the error */
+  if (err_e2 < err_e1) {
+    gdouble temp = eig[0];
+
+    eig[0] = eig[1];
+    eig[1] = -temp;
+  }
+
+  e1[0] = eig[0] * basis1[0] + eig[1] * basis2[0];
+  e1[1] = eig[0] * basis1[1] + eig[1] * basis2[1];
+  e1[2] = eig[0] * basis1[2] + eig[1] * basis2[2];
+  gts_vector_normalize (e1);
+
+  /* make N,e1,e2 a right handed coordinate sytem */
+  gts_vector_cross (e2, N, e1);
+  gts_vector_normalize (e2);
+}
diff --git a/gts/edge.c b/gts/edge.c
new file mode 100644
index 0000000..fde7d87
--- /dev/null
+++ b/gts/edge.c
@@ -0,0 +1,585 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "gts.h"
+
+gboolean gts_allow_floating_edges = FALSE;
+
+static void edge_destroy (GtsObject * object)
+{
+  GtsEdge * edge = GTS_EDGE (object);
+  GSList * i;
+
+  i = edge->triangles;
+  while (i) {
+    GSList * next = i->next;
+    gts_object_destroy (i->data);
+    i = next;
+  }
+  g_assert (edge->triangles == NULL);
+
+  (* GTS_OBJECT_CLASS (gts_edge_class ())->parent_class->destroy) (object);
+}
+
+static void edge_clone (GtsObject * clone, GtsObject * object)
+{
+  (* GTS_OBJECT_CLASS (gts_edge_class ())->parent_class->clone) (clone,
+								 object);
+  GTS_SEGMENT (clone)->v1 = GTS_SEGMENT (clone)->v2 = NULL;
+  GTS_EDGE (clone)->triangles = NULL;
+}
+
+static void edge_class_init (GtsObjectClass * klass)
+{
+  klass->clone = edge_clone;
+  klass->destroy = edge_destroy;
+}
+
+static void edge_init (GtsEdge * edge)
+{
+  edge->triangles = NULL;
+}
+
+/**
+ * gts_edge_class:
+ *
+ * Returns: the #GtsEdgeClass.
+ */
+GtsEdgeClass * gts_edge_class (void)
+{
+  static GtsEdgeClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo edge_info = {
+      "GtsEdge",
+      sizeof (GtsEdge),
+      sizeof (GtsEdgeClass),
+      (GtsObjectClassInitFunc) edge_class_init,
+      (GtsObjectInitFunc) edge_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_segment_class ()), 
+				  &edge_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_edge_new:
+ * @klass: a #GtsEdgeClass.
+ * @v1: a #GtsVertex.
+ * @v2: a #GtsVertex.
+ *
+ * Returns: a new #GtsEdge linking @v1 and @v2.
+ */
+GtsEdge * gts_edge_new (GtsEdgeClass * klass,
+			GtsVertex * v1, GtsVertex * v2)
+{
+  return GTS_EDGE (gts_segment_new (GTS_SEGMENT_CLASS (klass), v1, v2));
+}
+
+void gts_edge_remove(GtsEdge *edge) 
+{
+  edge->segment.v1->segments = g_slist_remove(edge->segment.v1->segments, &edge->segment);
+  edge->segment.v2->segments = g_slist_remove(edge->segment.v2->segments, &edge->segment);
+  edge_destroy(GTS_OBJECT (edge));
+}
+
+/**
+ * gts_edge_replace:
+ * @e: a #GtsEdge.
+ * @with: a #GtsEdge.
+ *
+ * Replaces @e with @with. For each triangle which uses @e as an
+ * edge, @e is replaced with @with. The @with->triangles list is
+ * updated appropriately and the @e->triangles list is freed and set
+ * to %NULL.
+ */
+void gts_edge_replace (GtsEdge * e, GtsEdge * with)
+{
+  GSList * i;
+
+  g_return_if_fail (e != NULL && with != NULL && e != with);
+
+  i = e->triangles;
+  while (i) {
+    GtsTriangle * t = i->data;
+    if (t->e1 == e) t->e1 = with;
+    if (t->e2 == e) t->e2 = with;
+    if (t->e3 == e) t->e3 = with;
+    if (!g_slist_find (with->triangles, t))
+      with->triangles = g_slist_prepend (with->triangles, t);
+    i = i->next;
+  }
+  g_slist_free (e->triangles);
+  e->triangles = NULL;
+}
+
+/**
+ * gts_edge_has_parent_surface:
+ * @e: a #GtsEdge.
+ * @surface: a #GtsSurface.
+ * 
+ * Returns: a #GtsFace of @surface having @e as an edge, %NULL otherwise.
+ */
+GtsFace * gts_edge_has_parent_surface (GtsEdge * e, GtsSurface * surface)
+{
+  GSList * i;
+
+  g_return_val_if_fail (e != NULL, NULL);
+
+  i = e->triangles;
+  while (i) {
+    if (GTS_IS_FACE (i->data) && 
+	gts_face_has_parent_surface (i->data, surface))
+      return i->data;
+    i = i->next;
+  }
+  return NULL;
+}
+
+/**
+ * gts_edge_has_any_parent_surface:
+ * @e: a #GtsEdge.
+ * 
+ * Returns: %NULL if @e is not an edge of any triangle or if all the
+ * faces having @e has an edge do not belong to any surface,
+ * a #GtsFace belonging to a surface and having @e as an edge.
+ */
+GtsFace * gts_edge_has_any_parent_surface (GtsEdge * e)
+{
+  GSList * i;
+
+  g_return_val_if_fail (e != NULL, NULL);
+
+  i = e->triangles;
+  while (i) {
+    GtsTriangle * t = i->data;
+    if (GTS_IS_FACE (t) && GTS_FACE (t)->surfaces != NULL)
+      return GTS_FACE (t);
+    i = i->next;
+  }
+  return NULL;
+}
+
+/**
+ * gts_edge_is_boundary:
+ * @e: a #GtsEdge.
+ * @surface: a #GtsSurface or %NULL.
+ * 
+ * Returns: the unique #GtsFace (which belongs to @surface) and which
+ * has @e as an edge (i.e. @e is a boundary edge (of @surface)) or %NULL 
+ * if there is more than one or no faces (belonging to @surface) and
+ * with @e as an edge.
+ */
+GtsFace * gts_edge_is_boundary (GtsEdge * e, GtsSurface * surface)
+{
+  GSList * i;
+  GtsFace * f = NULL;
+  
+  g_return_val_if_fail (e != NULL, NULL);
+  
+  i = e->triangles;
+  while (i) {
+    if (GTS_IS_FACE (i->data)) {
+      if (!surface || gts_face_has_parent_surface (i->data, surface)) {
+	if (f != NULL)
+	  return NULL;
+	f = i->data;
+      }
+    }
+    i = i->next;    
+  }
+  return f;
+}
+
+/**
+ * gts_edges_from_vertices:
+ * @vertices: a list of #GtsVertex.
+ * @parent: a #GtsSurface.
+ * 
+ * Returns: a list of unique #GtsEdge which have one of their vertices in 
+ * @vertices and are used by a face of @parent. 
+ */
+GSList * gts_edges_from_vertices (GSList * vertices, GtsSurface * parent)
+{
+  GHashTable * hash;
+  GSList * edges = NULL, * i;
+
+  g_return_val_if_fail (parent != NULL, NULL);
+  
+  hash = g_hash_table_new (NULL, NULL);
+  i = vertices;
+  while (i) {
+    GSList * j = GTS_VERTEX (i->data)->segments;
+    while (j) {
+      GtsSegment * s = j->data;
+      if (GTS_IS_EDGE (s) &&
+	  gts_edge_has_parent_surface (GTS_EDGE (s), parent) && 
+	  g_hash_table_lookup (hash, s) == NULL) {
+	edges = g_slist_prepend (edges, s);
+	g_hash_table_insert (hash, s, i);
+      }
+      j = j->next;
+    }
+    i = i->next;
+  }
+  g_hash_table_destroy (hash);
+  return edges;
+}
+
+/**
+ * gts_edge_face_number:
+ * @e: a #GtsEdge.
+ * @s: a #GtsSurface.
+ *
+ * Returns: the number of faces using @e and belonging to @s.
+ */
+guint gts_edge_face_number (GtsEdge * e, GtsSurface * s)
+{
+  GSList * i;
+  guint nt = 0;
+
+  g_return_val_if_fail (e != NULL, 0);
+  g_return_val_if_fail (s != NULL, 0);
+
+  i = e->triangles;
+  while (i) {
+    if (GTS_IS_FACE (i->data) && 
+	gts_face_has_parent_surface (GTS_FACE (i->data), s))
+      nt++;
+    i = i->next;
+  }
+  return nt;
+}
+
+/**
+ * gts_edge_is_duplicate:
+ * @e: a #GtsEdge.
+ *
+ * Returns: the first #GtsEdge different from @e which shares the
+ * same endpoints or %NULL if there is none.
+ */
+GtsEdge * gts_edge_is_duplicate (GtsEdge * e)
+{
+  GSList * i;
+  GtsVertex * v2;
+
+  g_return_val_if_fail (e != NULL, NULL);
+
+  v2 = GTS_SEGMENT (e)->v2;
+  i = GTS_SEGMENT (e)->v1->segments;
+  if (GTS_SEGMENT (e)->v1 == v2) /* e is degenerate: special treatment */
+    while (i) {
+      GtsSegment * s = i->data;
+      if (s != GTS_SEGMENT (e) &&
+	  GTS_IS_EDGE (s) && 
+	  s->v1 == v2 && s->v2 == v2)
+	return GTS_EDGE (s);
+      i = i->next;
+    }
+  else /* e is not degenerate */
+    while (i) {
+      GtsSegment * s = i->data;
+      if (s != GTS_SEGMENT (e) &&
+	  GTS_IS_EDGE (s) && 
+	  (s->v1 == v2 || s->v2 == v2))
+	return GTS_EDGE (s);
+      i = i->next;
+    }
+  return NULL;
+}
+
+/**
+ * gts_edges_merge:
+ * @edges: a list of #GtsEdge.
+ *
+ * For each edge in @edges check if it is duplicated (as
+ * returned by gts_edge_is_duplicate()). If it is replace it by its
+ * duplicate, destroy it and remove it from the list.
+ *
+ * Returns: the updated @edges list.
+ */
+GList * gts_edges_merge (GList * edges)
+{
+  GList * i = edges;
+
+  /* we want to control edge destruction */
+  gts_allow_floating_edges = TRUE;
+  while (i) {
+    GtsEdge * e = i->data;
+    GtsEdge * de = gts_edge_is_duplicate (e);
+    if (de) {
+      GList * next = i->next;
+      edges = g_list_remove_link (edges, i);
+      g_list_free_1 (i);
+      i = next;
+      gts_edge_replace (e, de);
+      gts_object_destroy (GTS_OBJECT (e));
+    }
+    else
+      i = i->next;
+  }
+  gts_allow_floating_edges = FALSE;;
+
+  return edges;
+}
+
+static void triangle_vertices_edges (GtsTriangle * t, 
+				     GtsEdge * e,
+				     GtsVertex ** v,
+				     GtsEdge ** ee1,
+				     GtsEdge ** ee2)
+{
+  GtsEdge * e1 = t->e1, * e2 = t->e2, * e3 = t->e3;
+  GtsVertex * v1 = GTS_SEGMENT (e)->v1;
+
+  if (e1 == e)        e1 = e3;
+  else if (e2 == e)   e2 = e3;
+  else                g_assert (e3 == e);
+
+  if (GTS_SEGMENT (e2)->v1 == v1 || GTS_SEGMENT (e2)->v2 == v1) {
+    e3 = e1; e1 = e2; e2 = e3;
+  }
+  if (GTS_SEGMENT (e1)->v1 == v1)
+    *v = GTS_SEGMENT (e1)->v2;
+  else
+    *v = GTS_SEGMENT (e1)->v1;
+  *ee1 = e1;
+  *ee2 = e2;
+}
+
+/**
+ * gts_edge_belongs_to_tetrahedron:
+ * @e: a #GtsEdge.
+ *
+ * Returns: %TRUE if @e is used by faces forming a tetrahedron, %FALSE
+ * otherwise.
+ */
+gboolean gts_edge_belongs_to_tetrahedron (GtsEdge * e)
+{
+  GSList * i;
+  GtsVertex * v1, * v2;
+
+  g_return_val_if_fail (e != NULL, FALSE);
+
+  v1 = GTS_SEGMENT (e)->v1;
+  v2 = GTS_SEGMENT (e)->v2;
+  i = e->triangles;
+  while (i) {
+    GtsEdge * e1, * e2;
+    GtsVertex * vt1;
+    GSList * j = i->next;
+    triangle_vertices_edges (i->data, e, &vt1, &e1, &e2);
+    while (j) {      
+      GtsSegment * s5;
+      GtsEdge * e3, * e4;
+      GtsVertex * vt2;
+
+      triangle_vertices_edges (j->data, e, &vt2, &e3, &e4);
+      s5 = gts_vertices_are_connected (vt1, vt2);
+      if (GTS_IS_EDGE (s5) &&
+	  gts_triangle_use_edges (e1, e3, GTS_EDGE (s5)) &&
+	  gts_triangle_use_edges (e2, e4, GTS_EDGE (s5)))
+	return TRUE;
+      j = j->next;
+    }
+    i = i->next;
+  }
+
+  return FALSE;
+}
+
+#define edge_use_vertex(e, v) (GTS_SEGMENT(e)->v1 == v ||\
+			       GTS_SEGMENT(e)->v2 == v)
+
+static GtsEdge * next_edge (GtsTriangle * t,
+			    GtsEdge * e1,
+			    GtsEdge * e)
+{
+  GtsVertex * v1 = GTS_SEGMENT (e)->v1;
+  GtsVertex * v2 = GTS_SEGMENT (e)->v2;
+  
+  if (t->e1 != e1 && t->e1 != e && 
+      (edge_use_vertex (t->e1, v1) || edge_use_vertex (t->e1, v2)))
+    return t->e1;
+  else if (t->e2 != e1 && t->e2 != e && 
+	   (edge_use_vertex (t->e2, v1) || edge_use_vertex (t->e2, v2)))
+    return t->e2;
+  else if (t->e3 != e1 && t->e3 != e && 
+	   (edge_use_vertex (t->e3, v1) || edge_use_vertex (t->e3, v2)))
+    return t->e3;
+  g_assert_not_reached ();
+  return NULL;
+}
+
+static void triangle_next (GtsEdge * e1, GtsEdge * e)
+{
+  GSList * i;
+
+  i = e1->triangles;
+  while (i) {
+    GtsTriangle * t = i->data;
+    if (GTS_OBJECT (t)->reserved) {
+      GTS_OBJECT (t)->reserved = NULL;
+      triangle_next (next_edge (t, e1, e), e);
+    }
+    i = i->next;
+  }
+}
+
+/** 
+ * gts_edge_is_contact: 
+ * @e: a #GtsEdge.  
+ *
+ * Returns: the number of sets of connected triangles sharing @e as a
+ * contact edge.  
+ */
+guint gts_edge_is_contact (GtsEdge * e)
+{
+  GSList * i, * triangles;
+  guint ncomponent = 0;
+
+  g_return_val_if_fail (e != NULL, 0);
+
+  triangles = gts_vertex_triangles (GTS_SEGMENT (e)->v1, NULL);
+  i = triangles = gts_vertex_triangles (GTS_SEGMENT (e)->v2, triangles);
+  while (i) {
+    GTS_OBJECT (i->data)->reserved = i;
+    i = i->next;
+  }
+
+  i = e->triangles;
+  while (i) {
+    GtsTriangle * t = i->data;
+    if (GTS_OBJECT (t)->reserved) {
+      GtsEdge * e1;
+      GTS_OBJECT (t)->reserved = NULL;
+      e1 = next_edge (t, NULL, e);
+      triangle_next (e1, e);
+      triangle_next (next_edge (t, e1, e), e);
+      ncomponent++;
+    }
+    i = i->next;
+  }
+   
+  g_slist_foreach (triangles, (GFunc) gts_object_reset_reserved, NULL);
+  g_slist_free (triangles);
+
+  return ncomponent;
+}
+
+/**
+ * gts_edge_swap:
+ * @e: a #GtsEdge.
+ * @s: a #GtsSurface.
+ *
+ * Performs an "edge swap" on the two triangles sharing @e and
+ * belonging to @s.
+ */
+void gts_edge_swap (GtsEdge * e, GtsSurface * s)
+{
+  GtsTriangle * t1 = NULL, * t2 = NULL, * t;
+  GtsFace * f;
+  GSList * i;
+  GtsVertex * v1, * v2, * v3, * v4, * v5, * v6;
+  GtsEdge * e1, * e2, * e3, * e4;
+  GtsSegment * v3v6;
+
+  g_return_if_fail (e != NULL);
+  g_return_if_fail (s != NULL);
+
+  i = e->triangles;
+  while (i) {
+    if (GTS_IS_FACE (i->data) && gts_face_has_parent_surface (i->data, s)) {
+      if (!t1)
+	t1 = i->data;
+      else if (!t2)
+	t2 = i->data;
+      else
+	g_return_if_fail (gts_edge_face_number (e, s) == 2);
+    }
+    i = i->next;
+  }
+  g_assert (t1 && t2);
+
+  gts_triangle_vertices_edges (t1, e, &v1, &v2, &v3, &e, &e1, &e2);
+  gts_triangle_vertices_edges (t2, e, &v4, &v5, &v6, &e, &e3, &e4);
+  g_assert (v2 == v4 && v1 == v5);
+
+  v3v6 = gts_vertices_are_connected (v3, v6);
+  if (!GTS_IS_EDGE (v3v6))
+    v3v6 = GTS_SEGMENT (gts_edge_new (s->edge_class, v3, v6));
+  f = gts_face_new (s->face_class, e1, GTS_EDGE (v3v6), e4);
+  if ((t = gts_triangle_is_duplicate (GTS_TRIANGLE (f))) &&
+      GTS_IS_FACE (t)) {
+    gts_object_destroy (GTS_OBJECT (f));
+    f = GTS_FACE (t);
+  }
+  gts_surface_add_face (s, f);
+
+  f = gts_face_new (s->face_class, GTS_EDGE (v3v6), e2, e3);
+  if ((t = gts_triangle_is_duplicate (GTS_TRIANGLE (f))) &&
+      GTS_IS_FACE (t)) {
+    gts_object_destroy (GTS_OBJECT (f));
+    f = GTS_FACE (t);
+  }
+  gts_surface_add_face (s, f);
+
+  gts_surface_remove_face (s, GTS_FACE (t1));
+  gts_surface_remove_face (s, GTS_FACE (t2));
+}
+
+/**
+ * gts_edge_manifold_faces:
+ * @e: a #GtsEdge.
+ * @s: a #GtsSurface.
+ * @f1: pointer for first face.
+ * @f2: pointer for second face.
+ *
+ * If @e is a manifold edge of surface @s, fills @f1 and @f2 with the
+ * faces belonging to @s and sharing @e.
+ *
+ * Returns: %TRUE if @e is a manifold edge, %FALSE otherwise.
+ */
+gboolean gts_edge_manifold_faces (GtsEdge * e, GtsSurface * s,
+				  GtsFace ** f1, GtsFace ** f2)
+{
+  GSList * i;
+
+  g_return_val_if_fail (e != NULL, FALSE);
+  g_return_val_if_fail (s != NULL, FALSE);
+  g_return_val_if_fail (f1 != NULL, FALSE);
+  g_return_val_if_fail (f2 != NULL, FALSE);
+
+  *f1 = *f2 = NULL;
+  i = e->triangles;
+  while (i) {
+    if (GTS_IS_FACE (i->data) && gts_face_has_parent_surface (i->data, s)) {
+      if (!(*f1)) *f1 = i->data;
+      else if (!(*f2)) *f2 = i->data;
+      else return FALSE;
+    }
+    i = i->next;
+  }
+
+  return (*f1 && *f2);
+}
diff --git a/gts/eheap.c b/gts/eheap.c
new file mode 100644
index 0000000..29f462d
--- /dev/null
+++ b/gts/eheap.c
@@ -0,0 +1,461 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <stdlib.h>
+#include "gts.h"
+
+#define PARENT(i) ((i) >= 2 ? (i)/2 : 0)
+#define LEFT_CHILD(i) (2*(i))
+#define RIGHT_CHILD(i) (2*(i) + 1)
+
+
+/**
+ * gts_eheap_new:
+ * @key_func: a #GtsKeyFunc or %NULL.
+ * @data: user data to be passed to @key_func.
+ *
+ * Returns: a new #GtsEHeap using @key_func as key.
+ */
+GtsEHeap * gts_eheap_new (GtsKeyFunc key_func,
+			  gpointer data)
+{
+  GtsEHeap * heap;
+
+  heap = g_malloc (sizeof(GtsEHeap));
+  heap->elts = g_ptr_array_new ();
+  heap->func = key_func;
+  heap->data = data;
+  heap->frozen = FALSE;
+  heap->randomized = FALSE;
+  return heap;
+}
+
+static void sift_up (GtsEHeap * heap, guint i)
+{
+  GtsEHeapPair * parent, * child;
+  guint p;
+  gpointer * pdata = heap->elts->pdata;
+  gdouble key;
+
+  child = pdata[i - 1];
+  key = child->key;
+  while ((p = PARENT (i))) {
+    parent = pdata[p - 1];
+    if (parent->key > key ||
+	(heap->randomized && parent->key == key && rand () < RAND_MAX/2)) {
+      pdata[p - 1] = child;
+      pdata[i - 1] = parent;
+      child->pos = p;
+      parent->pos = i;
+      i = p;
+    }
+    else
+      i = 0;
+  }
+}
+
+/**
+ * gts_eheap_insert:
+ * @heap: a #GtsEHeap.
+ * @p: a pointer to add to the heap.
+ *
+ * Inserts a new element @p in the heap.
+ *
+ * Returns: a #GtsEHeapPair describing the position of the element in the heap.
+ * This pointer is necessary for gts_eheap_remove() and 
+ * gts_eheap_decrease_key().
+ */
+GtsEHeapPair * gts_eheap_insert (GtsEHeap * heap, gpointer p)
+{
+  GtsEHeapPair * pair;
+  GPtrArray * elts;
+
+  g_return_val_if_fail (heap != NULL, NULL);
+  g_return_val_if_fail (heap->func != NULL, NULL);
+
+  elts = heap->elts;
+  pair = g_malloc (sizeof (GtsEHeapPair));
+  g_ptr_array_add (elts, pair);
+  pair->data = p;
+  pair->pos = elts->len;
+  pair->key = (*heap->func) (p, heap->data);
+  if (!heap->frozen)
+    sift_up (heap, elts->len);
+  return pair;
+}
+
+/**
+ * gts_eheap_insert_with_key:
+ * @heap: a #GtsEHeap.
+ * @p: a pointer to add to the heap.
+ * @key: the value of the key associated to @p.
+ *
+ * Inserts a new element @p in the heap.
+ *
+ * Returns: a #GtsEHeapPair describing the position of the element in the heap.
+ * This pointer is necessary for gts_eheap_remove() and 
+ * gts_eheap_decrease_key().
+ */
+GtsEHeapPair * gts_eheap_insert_with_key (GtsEHeap * heap, 
+					  gpointer p, 
+					  gdouble key)
+{
+  GtsEHeapPair * pair;
+  GPtrArray * elts;
+
+  g_return_val_if_fail (heap != NULL, NULL);
+
+  elts = heap->elts;
+  pair = g_malloc (sizeof (GtsEHeapPair));
+  g_ptr_array_add (elts, pair);
+  pair->data = p;
+  pair->pos = elts->len;
+  pair->key = key;
+  if (!heap->frozen)
+    sift_up (heap, elts->len);
+  return pair;
+}
+
+static void sift_down (GtsEHeap * heap, guint i)
+{
+  GtsEHeapPair * left_child, * right_child, * child, * parent;
+  guint lc, rc, c;
+  gpointer * pdata = heap->elts->pdata;
+  guint len = heap->elts->len;
+  gdouble key;
+
+  lc = LEFT_CHILD (i);
+  rc = RIGHT_CHILD (i);
+  left_child = lc <= len ? pdata[lc - 1] : NULL;
+  right_child = rc <= len ? pdata[rc - 1] : NULL;
+
+  parent = pdata[i - 1];
+  key = parent->key;
+  while (left_child != NULL) {
+    if (right_child == NULL || left_child->key  < right_child->key) {
+      child = left_child;
+      c = lc;
+    }
+    else {
+      child = right_child;
+      c = rc;
+    }
+    if (key > child->key) {
+      pdata[i - 1] = child;
+      child->pos = i;
+      pdata[c - 1] = parent;
+      parent->pos = c;
+      i = c;
+      lc = LEFT_CHILD (i);
+      rc = RIGHT_CHILD (i);
+      left_child = lc <= len ? pdata[lc - 1] : NULL;
+      right_child = rc <= len ? pdata[rc - 1] : NULL;      
+    }
+    else
+      left_child = NULL;
+  }
+}
+
+/**
+ * gts_eheap_remove_top:
+ * @heap: a #GtsEHeap.
+ * @key: a pointer on a gdouble or %NULL.
+ *
+ * Removes the element at the top of the heap and optionally (if @key is not
+ * %NULL) returns the value of its key.
+ *
+ * Returns: the element at the top of the heap.
+ */
+gpointer gts_eheap_remove_top (GtsEHeap * heap, gdouble * key)
+{
+  gpointer root;
+  GPtrArray * elts;
+  guint len;
+  GtsEHeapPair * pair;
+
+  g_return_val_if_fail (heap != NULL, NULL);
+
+  elts = heap->elts; 
+  len = elts->len;
+
+  if (len == 0)
+    return NULL;
+  if (len == 1) {
+    pair = g_ptr_array_remove_index (elts, 0);
+    root = pair->data;
+    if (key) 
+      *key = pair->key;
+    g_free (pair);
+    return root;
+  }
+
+  pair = elts->pdata[0];
+  root = pair->data;
+  if (key) 
+    *key = pair->key;
+  g_free (pair);
+  pair = g_ptr_array_remove_index (elts, len - 1);
+  elts->pdata[0] = pair;
+  pair->pos = 1;
+  sift_down (heap, 1);
+  return root;
+}
+
+/**
+ * gts_eheap_top:
+ * @heap: a #GtsEHeap.
+ * @key: a pointer on a gdouble or %NULL.
+ *
+ * Returns: the element at the top of the heap and optionally (if @key is not
+ * %NULL) its key.
+ */
+gpointer gts_eheap_top (GtsEHeap * heap, gdouble * key)
+{
+  GtsEHeapPair * pair;
+  GPtrArray * elts;
+
+  g_return_val_if_fail (heap != NULL, NULL);
+
+  elts = heap->elts;
+
+  if (elts->len == 0)
+    return NULL;
+
+  pair = elts->pdata[0];
+  if (key)
+    *key = pair->key;
+  return pair->data;
+}
+
+/**
+ * gts_eheap_destroy:
+ * @heap: a #GtsEHeap.
+ * 
+ * Free all the memory allocated for @heap.
+ */
+void gts_eheap_destroy (GtsEHeap * heap)
+{
+  guint i;
+
+  g_return_if_fail (heap != NULL);
+
+  for (i = 0; i < heap->elts->len; i++)
+    g_free (heap->elts->pdata[i]);
+  g_ptr_array_free (heap->elts, TRUE);
+  g_free (heap);
+}
+
+/**
+ * gts_eheap_thaw:
+ * @heap: a #GtsEHeap.
+ *
+ * If @heap has been frozen previously using gts_eheap_freeze(), reorder it
+ * in O(n) time and unfreeze it.
+ */
+void gts_eheap_thaw (GtsEHeap * heap)
+{
+  guint i;
+  
+  g_return_if_fail (heap != NULL);
+
+  if (!heap->frozen)
+    return;
+
+  for (i = heap->elts->len/2; i > 0; i--)
+    sift_down (heap, i);
+
+  heap->frozen = FALSE;
+}
+
+/**
+ * gts_eheap_foreach:
+ * @heap: a #GtsEHeap.
+ * @func: the function to call for each element in the heap.
+ * @data: to pass to @func.
+ */
+void gts_eheap_foreach (GtsEHeap * heap, 
+			GFunc func,
+			gpointer data)
+{
+  guint i;
+  GPtrArray * elts;
+  
+  g_return_if_fail (heap != NULL);
+  g_return_if_fail (func != NULL);
+
+  elts = heap->elts;
+  for (i = 0; i < elts->len; i++)
+    (*func) (((GtsEHeapPair *) elts->pdata[i])->data, data);
+}
+
+/**
+ * gts_eheap_remove:
+ * @heap: a #GtsEHeap.
+ * @p: a #GtsEHeapPair.
+ *
+ * Removes element corresponding to @p from @heap in O(log n).
+ *
+ * Returns: the element just removed from @heap.
+ */
+gpointer gts_eheap_remove (GtsEHeap * heap, GtsEHeapPair * p)
+{
+  GtsEHeapPair ** pdata;
+  GtsEHeapPair * parent;
+  guint i, par;
+  gpointer data;
+
+  g_return_val_if_fail (heap != NULL, NULL);
+  g_return_val_if_fail (p != NULL, NULL);
+
+  pdata = (GtsEHeapPair **)heap->elts->pdata;
+  i = p->pos;
+  data = p->data;
+
+  g_return_val_if_fail (i > 0 && i <= heap->elts->len, NULL);
+  g_return_val_if_fail (p == pdata[i - 1], NULL);
+
+  /* move element to the top */
+  while ((par = PARENT (i))) {
+    parent = pdata[par - 1];
+    pdata[par - 1] = p;
+    pdata[i - 1] = parent;
+    p->pos = par;
+    parent->pos = i;
+    i = par;
+  }
+
+  gts_eheap_remove_top (heap, NULL);
+
+  return data;
+}
+
+/**
+ * gts_eheap_decrease_key:
+ * @heap: a #GtsEHeap.
+ * @p: a #GtsEHeapPair.
+ * @new_key: the new value of the key for this element. Must be smaller than
+ * the current key.
+ *
+ * Decreases the value of the key of the element at position @p.
+ */
+void gts_eheap_decrease_key (GtsEHeap * heap, 
+			     GtsEHeapPair * p,
+			     gdouble new_key)
+{
+  guint i;
+
+  g_return_if_fail (heap != NULL);
+  g_return_if_fail (p != NULL);
+
+  i = p->pos;
+  g_return_if_fail (i > 0 && i <= heap->elts->len);
+  g_return_if_fail (p == heap->elts->pdata[i - 1]);
+
+  g_return_if_fail (new_key <= p->key);
+
+  p->key = new_key;
+  if (!heap->frozen)
+    sift_up (heap, i);
+}
+
+/**
+ * gts_eheap_freeze:
+ * @heap: a #GtsEHeap.
+ *
+ * Freezes the heap. Any subsequent operation will not preserve the heap
+ * property. Used in conjunction with gts_eheap_insert() and gts_eheap_thaw()
+ * to create a heap in O(n) time.
+ */
+void gts_eheap_freeze (GtsEHeap * heap)
+{
+  g_return_if_fail (heap != NULL);
+
+  heap->frozen = TRUE;
+}
+
+/**
+ * gts_eheap_size:
+ * @heap: a #GtsEHeap.
+ *
+ * Returns: the number of items in @heap.
+ */
+guint gts_eheap_size (GtsEHeap * heap)
+{
+  g_return_val_if_fail (heap != NULL, 0);
+
+  return heap->elts->len;
+}
+
+/**
+ * gts_eheap_update:
+ * @heap: a #GtsEHeap.
+ *
+ * Updates the key of each element of @heap and reorders it.
+ */
+void gts_eheap_update (GtsEHeap * heap)
+{
+  guint i, len;
+  GtsEHeapPair ** pairs;
+  gpointer data;
+  GtsKeyFunc func;
+
+  g_return_if_fail (heap != NULL);
+  g_return_if_fail (heap->func != NULL);
+
+  heap->frozen = TRUE;
+
+  len = heap->elts->len;
+  pairs = (GtsEHeapPair **) heap->elts->pdata;
+  data = heap->data;
+  func = heap->func;
+
+  for (i = 0; i < len; i++) {
+    GtsEHeapPair * pair = pairs[i];
+    pair->key = (*func) (pair->data, data);
+  }
+  
+  gts_eheap_thaw (heap);
+}
+
+/**
+ * gts_eheap_key:
+ * @heap: a #GtsEHeap.
+ * @p: a pointer to be tested;
+ *
+ * Returns: the value of the key for pointer @p.
+ */
+gdouble gts_eheap_key (GtsEHeap * heap, gpointer p)
+{
+  g_return_val_if_fail (heap != NULL, 0.);
+  g_return_val_if_fail (heap->func != NULL, 0.);
+
+  return (* heap->func) (p, heap->data);
+}
+
+/**
+ * gts_eheap_randomized:
+ * @heap: a #GtsEHeap.
+ * @randomized: whether @heap should be randomized.
+ */
+void gts_eheap_randomized (GtsEHeap * heap, gboolean randomized)
+{
+  g_return_if_fail (heap != NULL);
+
+  heap->randomized = randomized;
+}
diff --git a/gts/face.c b/gts/face.c
new file mode 100644
index 0000000..f6009f1
--- /dev/null
+++ b/gts/face.c
@@ -0,0 +1,297 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "gts.h"
+
+gboolean gts_allow_floating_faces = FALSE;
+
+static void face_destroy (GtsObject * object)
+{
+  GtsFace * face = GTS_FACE (object);
+  GSList * i;
+
+  i = face->surfaces;
+  while (i) {
+    GSList * next = i->next;
+    gts_surface_remove_face (i->data, face);
+    i = next;
+  }
+  g_assert (face->surfaces == NULL);
+
+  (* GTS_OBJECT_CLASS (gts_face_class ())->parent_class->destroy) (object);
+}
+
+static void face_clone (GtsObject * clone, GtsObject * object)
+{
+  (* GTS_OBJECT_CLASS (gts_face_class ())->parent_class->clone) (clone, 
+								 object);
+  GTS_FACE (clone)->surfaces = NULL;
+}
+
+static void face_class_init (GtsFaceClass * klass)
+{
+  GTS_OBJECT_CLASS (klass)->clone = face_clone;
+  GTS_OBJECT_CLASS (klass)->destroy = face_destroy;
+}
+
+static void face_init (GtsFace * face)
+{
+  face->surfaces = NULL;
+}
+
+/**
+ * gts_face_class:
+ *
+ * Returns: the #GtsFaceClass.
+ */
+GtsFaceClass * gts_face_class (void)
+{
+  static GtsFaceClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo face_info = {
+      "GtsFace",
+      sizeof (GtsFace),
+      sizeof (GtsFaceClass),
+      (GtsObjectClassInitFunc) face_class_init,
+      (GtsObjectInitFunc) face_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_triangle_class ()), 
+				  &face_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_face_new:
+ * @klass: a #GtsFaceClass.
+ * @e1: a #GtsEdge.
+ * @e2: a #GtsEdge.
+ * @e3: a #GtsEdge.
+ *
+ * Returns: a new #GtsFace using @e1, @e2 and @e3 as edges.
+ */
+GtsFace * gts_face_new (GtsFaceClass * klass,
+			GtsEdge * e1, GtsEdge * e2, GtsEdge * e3)
+{
+  GtsFace * f;
+
+  f = GTS_FACE (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  gts_triangle_set (GTS_TRIANGLE (f), e1, e2, e3);
+
+  return f;
+}
+
+/**
+ * gts_face_has_parent_surface:
+ * @f: a #GtsFace.
+ * @s: a #GtsSurface.
+ *
+ * Returns: %TRUE if @f belongs to @s, %FALSE otherwise.
+ */
+gboolean gts_face_has_parent_surface (GtsFace * f, GtsSurface * s)
+{
+  GSList * i;
+
+  g_return_val_if_fail (f != NULL, FALSE);
+
+  i = f->surfaces;
+  while (i) {
+    if (i->data == s)
+      return TRUE;
+    i = i->next;
+  }
+  return FALSE;
+}
+
+/**
+ * gts_faces_from_edges:
+ * @edges: a list of #GtsEdge.
+ * @s: a #GtsSurface or %NULL.
+ *
+ * Builds a list of unique faces which belong to @s and have
+ * one of their edges in @edges.
+ * 
+ * Returns: the list of faces.
+ */
+GSList * gts_faces_from_edges (GSList * edges, GtsSurface * s)
+{
+  GHashTable * hash;
+  GSList * faces = NULL, * i;
+
+  hash = g_hash_table_new (NULL, NULL);
+  i = edges;
+  while (i) {
+    GSList * j = GTS_EDGE (i->data)->triangles;
+    while (j) {
+      GtsTriangle * t = j->data;
+      if (GTS_IS_FACE (t) &&
+	  (!s || gts_face_has_parent_surface (GTS_FACE (t), s)) && 
+	  g_hash_table_lookup (hash, t) == NULL) {
+	faces = g_slist_prepend (faces, t);
+	g_hash_table_insert (hash, t, i);
+      }
+      j = j->next;
+    }
+    i = i->next;
+  }
+  g_hash_table_destroy (hash);
+
+  return faces;
+}
+
+/**
+ * gts_face_neighbor_number:
+ * @f: a #GtsFace.
+ * @s: a #GtsSurface or %NULL.
+ *
+ * Returns: the number of faces neighbors of @f and belonging to @s.
+ */
+guint gts_face_neighbor_number (GtsFace * f, GtsSurface * s)
+{
+  GSList * i;
+  guint nn = 0;
+  GtsEdge * e[4], ** e1 = e;
+  
+  g_return_val_if_fail (f != NULL, 0);
+  
+  e[0] = GTS_TRIANGLE (f)->e1; 
+  e[1] = GTS_TRIANGLE (f)->e2; 
+  e[2] = GTS_TRIANGLE (f)->e3; 
+  e[3] = NULL;
+  while (*e1) {
+    i = (*e1++)->triangles;
+    while (i) {
+      GtsTriangle * t = i->data;
+      if (GTS_FACE (t) != f && 
+	  GTS_IS_FACE (t) && 
+	  (!s || gts_face_has_parent_surface (GTS_FACE (t), s)))
+	nn++;
+      i = i->next;
+    }
+  }
+
+  return nn;
+}
+
+/**
+ * gts_face_neighbors:
+ * @f: a #GtsFace.
+ * @s: a #GtsSurface or %NULL.
+ *
+ * Returns: a list of unique #GtsFace neighbors of @f and belonging to @s.
+ */
+GSList * gts_face_neighbors (GtsFace * f, GtsSurface * s)
+{
+  GSList * i, * list = NULL;
+  GtsEdge * e[4], ** e1 = e;
+  
+  g_return_val_if_fail (f != NULL, NULL);
+
+  e[0] = GTS_TRIANGLE (f)->e1; 
+  e[1] = GTS_TRIANGLE (f)->e2; 
+  e[2] = GTS_TRIANGLE (f)->e3; 
+  e[3] = NULL;
+  while (*e1) {
+    i = (*e1++)->triangles;
+    while (i) {
+      GtsTriangle * t = i->data;
+      if (GTS_FACE (t) != f && 
+	  GTS_IS_FACE (t) && 
+	  (!s || gts_face_has_parent_surface (GTS_FACE (t), s)))
+	list = g_slist_prepend (list, t);
+      i = i->next;
+    }
+  }
+
+  return list;
+}
+
+/**
+ * gts_face_foreach_neighbor:
+ * @f: a #GtsFace.
+ * @s: a #GtsSurface or %NULL.
+ * @func: a #GtsFunc.
+ * @data: user data to pass to @func.
+ *
+ * Calls @func for each neighbor of @f belonging to @s (if not %NULL).
+ */
+void gts_face_foreach_neighbor (GtsFace * f, 
+				GtsSurface * s, 
+				GtsFunc func,
+				gpointer data)
+{
+  GSList * i;
+  GtsEdge * e[4], ** e1 = e;
+  
+  g_return_if_fail (f != NULL);
+  g_return_if_fail (func != NULL);
+
+  e[0] = GTS_TRIANGLE (f)->e1;
+  e[1] = GTS_TRIANGLE (f)->e2; 
+  e[2] = GTS_TRIANGLE (f)->e3; 
+  e[3] = NULL;
+  while (*e1) {
+    i = (*e1++)->triangles;
+    while (i) {
+      GtsTriangle * t = i->data;
+      if (GTS_FACE (t) != f && 
+	  GTS_IS_FACE (t) && 
+	  (!s || gts_face_has_parent_surface (GTS_FACE (t), s)))
+	(* func) (t, data);
+      i = i->next;
+    }
+  }
+}
+
+static gboolean triangle_is_incompatible (GtsTriangle * t, GtsEdge * e, GtsSurface * s)
+{
+  GSList * i = e->triangles;
+
+  while (i) {
+    if (i->data != t &&
+	GTS_IS_FACE (i->data) &&
+	gts_face_has_parent_surface (i->data, s) &&
+	!gts_triangles_are_compatible (t, i->data, e))
+      return TRUE;
+    i = i->next;
+  }
+  return FALSE;
+}
+
+/**
+ * gts_face_is_compatible:
+ * @f: a #GtsFace.
+ * @s: a #GtsSurface.
+ *
+ * Returns: %TRUE if @f is compatible with all its neighbors belonging
+ * to @s, %FALSE otherwise.
+ */
+gboolean gts_face_is_compatible (GtsFace * f, GtsSurface * s)
+{
+  g_return_val_if_fail (f != NULL, FALSE);
+  g_return_val_if_fail (s != NULL, FALSE);
+
+  return !(triangle_is_incompatible (GTS_TRIANGLE (f), GTS_TRIANGLE (f)->e1, s) ||
+	   triangle_is_incompatible (GTS_TRIANGLE (f), GTS_TRIANGLE (f)->e2, s) ||
+	   triangle_is_incompatible (GTS_TRIANGLE (f), GTS_TRIANGLE (f)->e3, s));
+}
diff --git a/gts/fifo.c b/gts/fifo.c
new file mode 100644
index 0000000..8b3d2b6
--- /dev/null
+++ b/gts/fifo.c
@@ -0,0 +1,192 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "gts.h"
+
+struct _GtsFifo {
+  GList * head;
+  GList * tail;
+};
+
+/**
+ * gts_fifo_new:
+ *
+ * Returns: a new #GtsFifo.
+ */
+GtsFifo * gts_fifo_new ()
+{
+  GtsFifo * fifo = g_malloc (sizeof (GtsFifo));
+
+  fifo->head = fifo->tail = NULL;
+  return fifo;
+}
+
+/**
+ * gts_fifo_write:
+ * @fifo: a #GtsFifo.
+ * @fp: a file pointer.
+ *
+ * Writes the content of @fifo in @fp.
+ */
+void gts_fifo_write (GtsFifo * fifo, FILE * fp)
+{
+  GList * i;
+
+  g_return_if_fail (fifo != NULL);
+  g_return_if_fail (fp != NULL);
+
+  fprintf (fp, "[");
+  i = fifo->head;
+  while (i) {
+    fprintf (fp, "%p ", i->data);
+    i = i->next;
+  }
+  fprintf (fp, "]");
+}
+
+/**
+ * gts_fifo_push:
+ * @fifo: a #GtsFifo.
+ * @data: data to add to @fifo.
+ *
+ * Push @data into @fifo.
+ */
+void gts_fifo_push (GtsFifo * fifo, gpointer data)
+{
+  g_return_if_fail (fifo != NULL);
+
+  fifo->head = g_list_prepend (fifo->head, data);
+  if (fifo->tail == NULL)
+    fifo->tail = fifo->head;
+}
+
+/**
+ * gts_fifo_pop:
+ * @fifo: a #GtsFifo.
+ *
+ * Removes the first element from @fifo.
+ *
+ * Returns: the first element in @fifo or %NULL if @fifo is empty.
+ */
+gpointer gts_fifo_pop (GtsFifo * fifo)
+{
+  gpointer data;
+  GList * tail;
+
+  g_return_val_if_fail (fifo != NULL, NULL);
+
+  if (fifo->tail == NULL)
+    return NULL;
+  tail = fifo->tail->prev;
+  data = fifo->tail->data;
+  fifo->head = g_list_remove_link (fifo->head, fifo->tail);
+  g_list_free_1 (fifo->tail);
+  fifo->tail = tail;
+  return data;
+}
+
+/**
+ * gts_fifo_top:
+ * @fifo: a #GtsFifo.
+ *
+ * Returns: the first element in @fifo or %NULL if @fifo is empty.
+ */
+gpointer gts_fifo_top (GtsFifo * fifo)
+{
+  g_return_val_if_fail (fifo != NULL, NULL);
+
+  if (fifo->tail == NULL)
+    return NULL;
+  return fifo->tail->data;
+}
+
+/**
+ * gts_fifo_size:
+ * @fifo: a #GtsFifo.
+ *
+ * Returns: the number of elements in @fifo.
+ */
+guint gts_fifo_size (GtsFifo * fifo)
+{
+  g_return_val_if_fail (fifo != NULL, 0);
+
+  return g_list_length (fifo->head);
+}
+
+/**
+ * gts_fifo_destroy:
+ * @fifo: a #GtsFifo.
+ *
+ * Frees all the memory allocated for @fifo.
+ */
+void gts_fifo_destroy (GtsFifo * fifo)
+{
+  g_return_if_fail (fifo != NULL);
+  g_list_free (fifo->head);
+  g_free (fifo);
+}
+
+/**
+ * gts_fifo_is_empty:
+ * @fifo: a #GtsFifo.
+ * 
+ * Returns: %TRUE if @fifo is empty, %FALSE otherwise.
+ */
+gboolean gts_fifo_is_empty (GtsFifo * fifo)
+{
+  g_return_val_if_fail (fifo != NULL, TRUE);
+
+  return (fifo->head == NULL);
+}
+
+/**
+ * gts_fifo_foreach:
+ * @fifo: a #GtsFifo.
+ * @func: a #GtsFunc.
+ * @data: user data to be passed to @func.
+ *
+ * Calls @func in order for each item in @fifo, passing @data.
+ */
+void gts_fifo_foreach (GtsFifo * fifo, GtsFunc func, gpointer data)
+{
+  GList * i;
+
+  g_return_if_fail (fifo != NULL);
+  g_return_if_fail (func != NULL);
+
+  i = fifo->tail;
+  while (i) {
+    (* func) (i->data, data);
+    i = i->prev;
+  }
+}
+
+/**
+ * gts_fifo_reverse:
+ * @fifo: a #GtsFifo.
+ *
+ * Reverses the order of elements in @fifo.
+ */
+void gts_fifo_reverse (GtsFifo * fifo)
+{
+  g_return_if_fail (fifo != NULL);
+
+  fifo->tail = fifo->head;
+  fifo->head = g_list_reverse (fifo->head);
+}
diff --git a/gts/graph.c b/gts/graph.c
new file mode 100644
index 0000000..1566c95
--- /dev/null
+++ b/gts/graph.c
@@ -0,0 +1,1776 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <math.h>
+#include <stdlib.h>
+#include "gts.h"
+
+/* GtsGNode */
+
+gboolean gts_allow_floating_gnodes = FALSE;
+
+static void gnode_remove_container (GtsContainee * i, GtsContainer * c)
+{
+  (* GTS_CONTAINEE_CLASS (GTS_OBJECT_CLASS (gts_gnode_class ())->parent_class)->remove_container) (i, c);
+  if (GTS_SLIST_CONTAINEE (i)->containers == NULL && 
+      !gts_allow_floating_gnodes &&
+      !GTS_OBJECT_DESTROYED(GTS_OBJECT (i)))
+    gts_object_destroy (GTS_OBJECT (i));
+}
+
+static void gnode_class_init (GtsGNodeClass * klass)
+{
+  klass->weight = NULL;
+
+  GTS_CONTAINEE_CLASS (klass)->remove_container = gnode_remove_container;
+}
+
+static void gnode_init (GtsGNode * n)
+{
+  n->level = 0;
+}
+
+/**
+ * gts_gnode_class:
+ * 
+ * Returns: the #GtsGNodeClass.
+ */
+GtsGNodeClass * gts_gnode_class (void)
+{
+  static GtsGNodeClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo gnode_info = {
+      "GtsGNode",
+      sizeof (GtsGNode),
+      sizeof (GtsGNodeClass),
+      (GtsObjectClassInitFunc) gnode_class_init,
+      (GtsObjectInitFunc) gnode_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = 
+      gts_object_class_new (GTS_OBJECT_CLASS (gts_slist_container_class ()),
+			    &gnode_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_gnode_new:
+ * @klass: a #GtsGNodeClass.
+ *
+ * Returns: a new #GtsGNode.
+ */
+GtsGNode * gts_gnode_new (GtsGNodeClass * klass)
+{
+  GtsGNode * object;
+
+  object = GTS_GNODE (gts_object_new (GTS_OBJECT_CLASS (klass)));
+
+  return object;
+}
+
+/**
+ * gts_gnode_foreach_neighbor:
+ * @n: a #GtsGNode.
+ * @g: a #GtsGraph or %NULL.
+ * @func: a #GtsFunc.
+ * @data: user data to be passed to @func.
+ *
+ * Calls @func for each neighbor #GtsGNode of @n (belonging to @g if
+ * @g is not %NULL.  
+ */
+void gts_gnode_foreach_neighbor (GtsGNode * n, 
+				 GtsGraph * g,
+				 GtsFunc func,
+				 gpointer data)
+{
+  GSList * i;
+
+  g_return_if_fail (n != NULL);
+  g_return_if_fail (func != NULL);
+
+  i = GTS_SLIST_CONTAINER (n)->items;
+  while (i) {
+    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
+    if (g == NULL || gts_containee_is_contained (GTS_CONTAINEE (n1),
+						 GTS_CONTAINER (g)))
+      (* func) (n1, data);
+    i = i->next;
+  }
+}
+
+/**
+ * gts_gnode_foreach_edge:
+ * @n: a #GtsGNode.
+ * @g: a #GtsGraph or %NULL.
+ * @func: a #GtsFunc.
+ * @data: user data to be passed to @func.
+ *
+ * Calls @func for each #GtsGEdge connecting @n to another #GtsGNode
+ * (belonging to @g if @g is not %NULL.  
+ */
+void gts_gnode_foreach_edge (GtsGNode * n, 
+			     GtsGraph * g,
+			     GtsFunc func,
+			     gpointer data)
+{
+  GSList * i;
+
+  g_return_if_fail (n != NULL);
+  g_return_if_fail (func != NULL);
+
+  i = GTS_SLIST_CONTAINER (n)->items;
+  while (i) {
+    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
+    if (g == NULL || gts_containee_is_contained (GTS_CONTAINEE (n1),
+						 GTS_CONTAINER (g)))
+      (* func) (i->data, data);
+    i = i->next;
+  }
+}
+
+/**
+ * gts_gnode_degree:
+ * @n: a #GtsGNode.
+ * @g: a #GtsGraph or %NULL.
+ *
+ * Returns: the number of neighbors of @n (belonging to @g if @g is not %NULL).
+ */
+guint gts_gnode_degree (GtsGNode * n,
+			GtsGraph * g)
+{
+  GSList * i;
+  guint nn = 0;
+
+  g_return_val_if_fail (n != NULL, 0);
+
+  i = GTS_SLIST_CONTAINER (n)->items;
+  while (i) {
+    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
+    if (g == NULL || gts_containee_is_contained (GTS_CONTAINEE (n1),
+						 GTS_CONTAINER (g)))
+      nn++;
+    i = i->next;
+  }
+
+  return nn;
+}
+
+/**
+ * gts_gnode_move_cost:
+ * @n: a #GtsGNode.
+ * @src: a #GtsGraph containing @n.
+ * @dst: another #GtsGraph.
+ *
+ * Returns: the cost (increase in the sum of the weights of the edges cut) of
+ * moving @n from @src to @dst.
+ */
+gfloat gts_gnode_move_cost (GtsGNode * n,
+			    GtsGraph * src,
+			    GtsGraph * dst)
+{
+  GSList * i;
+  gfloat cost = 0.;
+  
+  g_return_val_if_fail (n != NULL, G_MAXFLOAT);
+  g_return_val_if_fail (src != NULL, G_MAXFLOAT);
+  g_return_val_if_fail (dst != NULL, G_MAXFLOAT);
+  g_return_val_if_fail (gts_containee_is_contained (GTS_CONTAINEE (n),
+						    GTS_CONTAINER (src)),
+			G_MAXFLOAT);
+
+  i = GTS_SLIST_CONTAINER (n)->items;
+  while (i) {
+    GtsGEdge * ge = i->data;
+    GtsGNode * neighbor = GTS_GNODE_NEIGHBOR (n, ge);
+
+    if (gts_containee_is_contained (GTS_CONTAINEE (neighbor), 
+				    GTS_CONTAINER (src)))
+      cost += gts_gedge_weight (ge);
+    else if (gts_containee_is_contained (GTS_CONTAINEE (neighbor), 
+					 GTS_CONTAINER (dst)))
+      cost -= gts_gedge_weight (ge);
+    i = i->next;
+  }
+  
+  return cost;
+}
+
+/**
+ * gts_gnode_weight:
+ * @n: a #GtsGNode.
+ *
+ * Returns: the weight of @n as defined by the weight() method of the
+ * #GtsGNodeClass.  
+ */
+gfloat gts_gnode_weight (GtsGNode * n)
+{
+  g_return_val_if_fail (n != NULL, 0.);
+
+  if (GTS_GNODE_CLASS (GTS_OBJECT (n)->klass)->weight)
+    return (* GTS_GNODE_CLASS (GTS_OBJECT (n)->klass)->weight) (n);
+  return 1.;
+}
+
+/* GtsNGNode */
+
+static void ngnode_init (GtsNGNode * n)
+{
+  n->id = 0;
+}
+
+/**
+ * gts_ngnode_class:
+ *
+ * Returns: the #GtsNGNodeClass.
+ */
+GtsNGNodeClass * gts_ngnode_class (void)
+{
+  static GtsNGNodeClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo ngnode_info = {
+      "GtsNGNode",
+      sizeof (GtsNGNode),
+      sizeof (GtsNGNodeClass),
+      (GtsObjectClassInitFunc) NULL,
+      (GtsObjectInitFunc) ngnode_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_gnode_class ()),
+				  &ngnode_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_ngnode_new:
+ * @klass: a #GtsNGNodeClass.
+ *
+ * Returns: a new #GtsNGNode with identity @id.
+ */
+GtsNGNode * gts_ngnode_new (GtsNGNodeClass * klass,
+			    guint id)
+{
+  GtsNGNode * n;
+
+  n = GTS_NGNODE (gts_gnode_new (GTS_GNODE_CLASS (klass)));
+  n->id = id;
+
+  return n;
+}
+
+/* GtsWGNode */
+
+static gfloat wgnode_weight (GtsGNode * n)
+{
+  return GTS_WGNODE (n)->weight;
+}
+
+static void wgnode_class_init (GtsWGNodeClass * klass)
+{
+  GTS_GNODE_CLASS (klass)->weight = wgnode_weight;
+}
+
+static void wgnode_init (GtsWGNode * n)
+{
+  n->weight = 1.;
+}
+
+/**
+ * gts_wgnode_class:
+ *
+ * Returns: the #GtsWGNodeClass.
+ */
+GtsWGNodeClass * gts_wgnode_class (void)
+{
+  static GtsWGNodeClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo wgnode_info = {
+      "GtsWGNode",
+      sizeof (GtsWGNode),
+      sizeof (GtsWGNodeClass),
+      (GtsObjectClassInitFunc) wgnode_class_init,
+      (GtsObjectInitFunc) wgnode_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_gnode_class ()),
+				  &wgnode_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_wgnode_new:
+ * @klass: a #GtsWGNodeClass.
+ * @weight: the weight of the #GtsWGNode to create.
+ *
+ * Returns: a new #GtsWGNode of weight @weight.
+ */
+GtsWGNode * gts_wgnode_new (GtsWGNodeClass * klass,
+			    gfloat weight)
+{
+  GtsWGNode * n;
+
+  n = GTS_WGNODE (gts_gnode_new (GTS_GNODE_CLASS (klass)));
+  n->weight = weight;
+
+  return n;
+}
+
+/* GtsPNode */
+
+static void pnode_write (GtsGNode * n, FILE * fp)
+{
+  if (GTS_IS_NVERTEX (GTS_PNODE (n)->data))
+    fprintf (fp, "label=\"%p:%s\",", 
+	     GTS_PNODE (n)->data,
+	     GTS_NVERTEX (GTS_PNODE (n)->data)->name);
+  else
+    fprintf (fp, "label=\"%p\",", GTS_PNODE (n)->data);
+}
+
+static void pnode_class_init (GtsPNodeClass * klass)
+{
+  GTS_GNODE_CLASS (klass)->write = pnode_write;
+}
+
+static void pnode_init (GtsPNode * pn)
+{
+  pn->data = NULL;
+}
+
+/**
+ * gts_pnode_class:
+ *
+ * Returns: the #GtsPNodeClass.
+ */
+GtsPNodeClass * gts_pnode_class (void)
+{
+  static GtsPNodeClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo pnode_info = {
+      "GtsPNode",
+      sizeof (GtsPNode),
+      sizeof (GtsPNodeClass),
+      (GtsObjectClassInitFunc) pnode_class_init,
+      (GtsObjectInitFunc) pnode_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_gnode_class ()),
+				  &pnode_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_pnode_new:
+ * @klass: a #GtsPNodeClass.
+ * @data: user data.
+ *
+ * Returns: a new #GtsPNode associated with @data.
+ */
+GtsPNode * gts_pnode_new (GtsPNodeClass * klass, gpointer data)
+{
+  GtsPNode * pn;
+
+  pn = GTS_PNODE (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  pn->data = data;
+
+  return pn;
+}
+
+/* GtsFNode */
+
+static void fnode_write (GtsGNode * n, FILE * fp)
+{
+  fprintf (fp, "label=\"%p\",", GTS_FNODE (n)->f);
+}
+
+static void fnode_class_init (GtsGNodeClass * klass)
+{
+  klass->write = fnode_write;
+}
+
+static void fnode_init (GtsFNode * fn)
+{
+  fn->f = NULL;
+}
+
+/**
+ * gts_fnode_class:
+ *
+ * Returns: the #GtsFNodeClass.
+ */
+GtsFNodeClass * gts_fnode_class (void)
+{
+  static GtsFNodeClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo fnode_info = {
+      "GtsFNode",
+      sizeof (GtsFNode),
+      sizeof (GtsFNodeClass),
+      (GtsObjectClassInitFunc) fnode_class_init,
+      (GtsObjectInitFunc) fnode_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_gnode_class ()),
+				  &fnode_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_fnode_new:
+ * @klass: a #GtsFNodeClass.
+ * @f: a #GtsFace.
+ *
+ * Returns: a new #GtsFNode associated with face @f.
+ */
+GtsFNode * gts_fnode_new (GtsFNodeClass * klass, GtsFace * f)
+{
+  GtsFNode * fn;
+
+  g_return_val_if_fail (f != NULL, NULL);
+
+  fn = GTS_FNODE (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  fn->f = f;
+
+  return fn;
+}
+
+/* GtsGEdge */
+
+static void gedge_destroy (GtsObject * object)
+{
+  GtsGEdge * ge = GTS_GEDGE (object);
+
+  if (ge->n1)
+    gts_container_remove (GTS_CONTAINER (ge->n1), GTS_CONTAINEE (ge));
+  if (ge->n2)
+    gts_container_remove (GTS_CONTAINER (ge->n2), GTS_CONTAINEE (ge));
+
+  (* GTS_OBJECT_CLASS (gts_gedge_class ())->parent_class->destroy) (object);
+}
+
+static void gedge_remove_container (GtsContainee * i, GtsContainer * c)
+{
+  GtsGEdge * ge = GTS_GEDGE (i);
+  GtsGNode * n1 = ge->n1;
+  GtsGNode * n2 = ge->n2;
+
+  ge->n1 = ge->n2 = NULL;
+  if (n1 != NULL && n2 != NULL) {
+    if (GTS_CONTAINER (n1) == c) {
+      if (n2 && n2 != n1) gts_container_remove (GTS_CONTAINER (n2), i);
+    }
+    else if (GTS_CONTAINER (n2) == c) {
+      if (n1 && n1 != n2) gts_container_remove (GTS_CONTAINER (n1), i);
+    }
+    else
+      g_assert_not_reached ();
+    (* GTS_OBJECT_CLASS (gts_gedge_class ())->parent_class->destroy)
+      (GTS_OBJECT (i));
+  }
+}
+
+static gboolean gedge_is_contained (GtsContainee * i, GtsContainer * c)
+{
+  GtsGEdge * ge = GTS_GEDGE (i);
+
+  if (GTS_CONTAINER (ge->n1) == c || GTS_CONTAINER (ge->n2) == c)
+    return TRUE;
+  return FALSE;
+}
+
+static void gedge_class_init (GtsGEdgeClass * klass)
+{
+  klass->link = NULL;
+  klass->weight = NULL;
+
+  GTS_CONTAINEE_CLASS (klass)->remove_container = gedge_remove_container;
+  GTS_CONTAINEE_CLASS (klass)->is_contained = gedge_is_contained;
+
+  GTS_OBJECT_CLASS (klass)->destroy = gedge_destroy;
+}
+
+static void gedge_init (GtsGEdge * object)
+{
+  object->n1 = object->n2 = NULL;
+}
+
+/**
+ * gts_gedge_class:
+ *
+ * Returns: the #GtsGEdgeClass.
+ */
+GtsGEdgeClass * gts_gedge_class (void)
+{
+  static GtsGEdgeClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo gedge_info = {
+      "GtsGEdge",
+      sizeof (GtsGEdge),
+      sizeof (GtsGEdgeClass),
+      (GtsObjectClassInitFunc) gedge_class_init,
+      (GtsObjectInitFunc) gedge_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_containee_class ()),
+				  &gedge_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_gedge_new:
+ * @klass: a #GtsGEdgeClass.
+ * @n1: a #GtsGNode.
+ * @n2: another #GtsGNode.
+ *
+ * Returns: a new #GtsGEdge linking @n1 and @n2.
+ */
+GtsGEdge * gts_gedge_new (GtsGEdgeClass * klass, GtsGNode * n1, GtsGNode * n2)
+{
+  GtsGEdge * object;
+
+  g_return_val_if_fail (n1 != NULL, NULL);
+  g_return_val_if_fail (n2 != NULL, NULL);
+
+  object = GTS_GEDGE (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  object->n1 = n1;
+  gts_container_add (GTS_CONTAINER (n1), GTS_CONTAINEE (object));
+  object->n2 = n2;
+  if (n1 != n2)
+    gts_container_add (GTS_CONTAINER (n2), GTS_CONTAINEE (object));
+
+  if (klass->link)
+    object = (* klass->link) (object, n1, n2);
+
+  return object;
+}
+
+/**
+ * gts_gedge_weight:
+ * @e: a #GtsGEdge.
+ *
+ * Returns: the weight of edge @e as defined by the weight() method of
+ * #GtsGEdgeClass.  
+ */
+gfloat gts_gedge_weight (GtsGEdge * e)
+{
+  g_return_val_if_fail (e != NULL, 0.);
+
+  if (GTS_GEDGE_CLASS (GTS_OBJECT (e)->klass)->weight)
+    return (* GTS_GEDGE_CLASS (GTS_OBJECT (e)->klass)->weight) (e);
+  return 1.;
+}
+
+/* GtsPGEdge */
+
+static void pgedge_write (GtsGEdge * ge, FILE * fp)
+{
+  if (GTS_IS_EDGE (GTS_PGEDGE (ge)->data)) {
+    GtsEdge * e = GTS_PGEDGE (ge)->data;
+    guint n = g_slist_length (e->triangles);
+
+    fprintf (fp, "label=\"%p:%s:%d\",color=%s", e,
+	     GTS_IS_NEDGE (e) ? GTS_NEDGE (e)->name : "",
+	     n,
+	     n == 0 ? "black" : 
+             n == 1 ? "blue" :
+	     n == 2 ? "green" :
+	     n == 3 ? "violet" :
+	     n == 4 ? "red" : 
+	     "pink");
+  }
+  else
+    fprintf (fp, "label=\"%p\",", GTS_PGEDGE (ge)->data);
+}
+
+static void pgedge_class_init (GtsPGEdgeClass * klass)
+{
+  GTS_GEDGE_CLASS (klass)->write = pgedge_write;
+}
+
+static void pgedge_init (GtsPGEdge * e)
+{
+  e->data = NULL;
+}
+
+/**
+ * gts_pgedge_class:
+ * 
+ * Returns: the #GtsPGEdgeClass.
+ */
+GtsPGEdgeClass * gts_pgedge_class (void)
+{
+  static GtsPGEdgeClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo pgedge_info = {
+      "GtsPGEdge",
+      sizeof (GtsPGEdge),
+      sizeof (GtsPGEdgeClass),
+      (GtsObjectClassInitFunc) pgedge_class_init,
+      (GtsObjectInitFunc) pgedge_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_gedge_class ()),
+				  &pgedge_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_pgedge_new:
+ * @klass: a #GtsPGEdgeClass.
+ * @n1: a #GtsGNode.
+ * @n2: another #GtsGNode.
+ * @data: user data.
+ *
+ * Returns: a new #GtsPGEdge associated with @data linking @n1 and @n2.
+ */ 
+GtsPGEdge * gts_pgedge_new (GtsPGEdgeClass * klass,
+			    GtsGNode * g1,
+			    GtsGNode * g2,
+			    gpointer data)
+{
+  GtsPGEdge * we;
+
+  we = GTS_PGEDGE (gts_gedge_new (GTS_GEDGE_CLASS (klass), g1, g2));
+  we->data = data;
+
+  return we;
+}
+
+/* GtsWGEdge */
+
+static gfloat wgedge_weight (GtsGEdge * e)
+{
+  return GTS_WGEDGE (e)->weight;
+}
+
+static void wgedge_class_init (GtsWGEdgeClass * klass)
+{
+  GTS_GEDGE_CLASS (klass)->weight = wgedge_weight;
+}
+
+static void wgedge_init (GtsWGEdge * e)
+{
+  e->weight = 1.;
+}
+
+/**
+ * gts_wgedge_class:
+ * 
+ * Returns: the #GtsWGEdgeClass.
+ */
+GtsWGEdgeClass * gts_wgedge_class (void)
+{
+  static GtsWGEdgeClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo wgedge_info = {
+      "GtsWGEdge",
+      sizeof (GtsWGEdge),
+      sizeof (GtsWGEdgeClass),
+      (GtsObjectClassInitFunc) wgedge_class_init,
+      (GtsObjectInitFunc) wgedge_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_gedge_class ()),
+				  &wgedge_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_wgedge_new:
+ * @klass: a #GtsWGEdgeClass.
+ * @n1: a #GtsGNode.
+ * @n2: another #GtsGNode.
+ * @weight: the weight of the new edge.
+ *
+ * Returns: a new #GtsWGEdge of weight @weight linking @n1 and @n2.
+ */ 
+GtsWGEdge * gts_wgedge_new (GtsWGEdgeClass * klass,
+			    GtsGNode * g1,
+			    GtsGNode * g2,
+			    gfloat weight)
+{
+  GtsWGEdge * we;
+
+  we = GTS_WGEDGE (gts_gedge_new (GTS_GEDGE_CLASS (klass), g1, g2));
+  we->weight = weight;
+
+  return we;
+}
+
+/* GtsGraph */
+
+static void graph_init (GtsGraph * g)
+{
+  g->graph_class = gts_graph_class ();
+  g->node_class  = gts_gnode_class ();
+  g->edge_class  = gts_gedge_class ();
+}
+
+static void graph_write (GtsObject * object, FILE * fp)
+{
+  GtsGraph * graph = GTS_GRAPH (object);
+
+  fprintf (fp, " %s %s %s",
+	   object->klass->info.name,
+	   GTS_OBJECT_CLASS (graph->node_class)->info.name,
+	   GTS_OBJECT_CLASS (graph->edge_class)->info.name);
+}
+
+static void graph_read (GtsObject ** object, GtsFile * f)
+{
+  GtsObjectClass * klass;
+
+  if (f->type != GTS_STRING) {
+    gts_file_error (f, "expecting a string (GtsGNodeClass)");
+    return;
+  }
+  klass = gts_object_class_from_name (f->token->str);
+  if (klass == NULL) {
+    gts_file_error (f, "unknown class `%s'", f->token->str);
+    return;
+  }
+  if (!gts_object_class_is_from_class (klass, gts_gnode_class ())) {
+    gts_file_error (f, "class `%s' is not a GtsGNodeClass", f->token->str);
+    return;
+  }
+  GTS_GRAPH (*object)->node_class = GTS_GNODE_CLASS (klass);
+  gts_file_next_token (f);
+
+  if (f->type != GTS_STRING) {
+    gts_file_error (f, "expecting a string (GtsGEdgeClass)");
+    return;
+  }
+  klass = gts_object_class_from_name (f->token->str);
+  if (klass == NULL) {
+    gts_file_error (f, "unknown class `%s'", f->token->str);
+    return;
+  }
+  if (!gts_object_class_is_from_class (klass, gts_gedge_class ())) {
+    gts_file_error (f, "class `%s' is not a GtsGEdgeClass", f->token->str);
+    return;
+  }
+  GTS_GRAPH (*object)->edge_class = GTS_GEDGE_CLASS (klass);
+  gts_file_next_token (f);
+}
+
+static void graph_class_init (GtsGraphClass * klass)
+{
+  klass->weight = NULL;
+
+  GTS_OBJECT_CLASS (klass)->write = graph_write;
+  GTS_OBJECT_CLASS (klass)->read = graph_read;
+}
+
+/**
+ * gts_graph_class:
+ *
+ * Returns: the #GtsGraphClass.
+ */
+GtsGraphClass * gts_graph_class (void)
+{
+  static GtsGraphClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo graph_info = {
+      "GtsGraph",
+      sizeof (GtsGraph),
+      sizeof (GtsGraphClass),
+      (GtsObjectClassInitFunc) graph_class_init,
+      (GtsObjectInitFunc) graph_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_hash_container_class ()),
+				  &graph_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_graph_new:
+ * @klass: a #GtsGraphClass.
+ * @node_class: a #GtsGNodeClass.
+ * @edge_class: a #GtsGEdgeClass.
+ *
+ * Returns: a new #GtsGraph using @node_class and @edge_class as node types.
+ */
+GtsGraph * gts_graph_new (GtsGraphClass * klass,
+			  GtsGNodeClass * node_class,
+			  GtsGEdgeClass * edge_class)
+{
+  GtsGraph * g;
+
+  g_return_val_if_fail (klass != NULL, NULL);
+  g_return_val_if_fail (node_class != NULL, NULL);
+  g_return_val_if_fail (edge_class != NULL, NULL);
+
+  g = GTS_GRAPH (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  g->node_class = node_class;
+  g->edge_class = edge_class;
+
+  return g;
+}
+
+static void compute_degree (GtsGNode * n, gpointer * data)
+{
+  GtsGraph * g = data[0];
+  GtsRange * degree = data[1];
+
+  gts_range_add_value (degree, gts_gnode_degree (n, g));
+}
+
+/**
+ * gts_graph_print_stats:
+ * @g: a #GtsGraph.
+ * @fp: a file pointer.
+ *
+ * Writes to @fp a summary of the properties of @g.
+ */
+void gts_graph_print_stats (GtsGraph * g, FILE * fp)
+{
+  GtsRange degree;
+  gpointer data[2];
+
+  g_return_if_fail (g != NULL);
+  g_return_if_fail (fp != NULL);
+
+  fprintf (fp, "# nodes: %d weight: %g\n", 
+	   gts_container_size (GTS_CONTAINER (g)),
+	   gts_graph_weight (g));
+  fprintf (fp, "#   degree: ");
+  gts_range_init (&degree);
+  data[0] = g;
+  data[1] = &degree;
+  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) compute_degree, data);
+  gts_range_update (&degree);
+  gts_range_print (&degree, fp);
+  fprintf (fp, "\n");
+  fprintf (fp, "#   edges cut: %d edges cut weight: %g\n", 
+	   gts_graph_edges_cut (g),
+	   gts_graph_edges_cut_weight (g));
+}
+
+struct _GtsGraphTraverse {
+  GtsFifo * q;
+  GtsGraph * g;
+};
+
+static void reset_level (GtsGNode * n)
+{
+  n->level = 0;
+}
+
+/**
+ * gts_graph_traverse_new:
+ * @g: a #GtsGraph.
+ * @n: a #GtsGNode belonging to @g.
+ * @type: the type of traversal.
+ * @reinit: if %TRUE, the traversal is reinitialized.
+ *
+ * Returns: a new #GtsGraphTraverse initialized for the traversal of
+ * @g of type @type, starting from @n.  
+ */
+GtsGraphTraverse * gts_graph_traverse_new (GtsGraph * g, 
+					   GtsGNode * n,
+					   GtsTraverseType type,
+					   gboolean reinit)
+{
+  GtsGraphTraverse * t;
+
+  g_return_val_if_fail (g != NULL, NULL);
+  g_return_val_if_fail (n != NULL, NULL);
+  g_return_val_if_fail (gts_containee_is_contained (GTS_CONTAINEE (n), 
+						    GTS_CONTAINER (g)), 
+			NULL);
+
+  if (reinit)
+    gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) reset_level, NULL);
+
+  t = g_malloc (sizeof (GtsGraphTraverse));
+  t->q = gts_fifo_new ();
+  t->g = g;
+  n->level = 1;
+  gts_fifo_push (t->q, n);
+
+  return t;
+}
+
+static void push_neighbor (GtsGNode * n, gpointer * data)
+{
+  GtsFifo * q = data[0];
+  GtsGNode * u = data[1];
+
+  if (n->level == 0) {
+    n->level = u->level + 1;
+    gts_fifo_push (q, n);
+  }
+}
+
+/**
+ * gts_graph_traverse_next:
+ * @t: a #GtsGraphTraverse.
+ *
+ * Returns: the next #GtsGNode of the traversal defined by @t or %NULL
+ * if the traversal is complete.
+ */
+GtsGNode * gts_graph_traverse_next (GtsGraphTraverse * t) 
+{ 
+  GtsGNode * u;
+
+  g_return_val_if_fail (t != NULL, NULL);
+
+  u = gts_fifo_pop (t->q);
+  if (u) {
+    gpointer data[2];
+
+    data[0] = t->q;
+    data[1] = u;
+    gts_gnode_foreach_neighbor (u, t->g, (GtsFunc) push_neighbor, data);
+  }
+  
+  return u;
+}
+
+/**
+ * gts_graph_traverse_what_next:
+ * @t: a #GtsGraphTraverse.
+ *
+ * Returns: the next #GtsGNode of the traversal defined by @t or %NULL
+ * if the traversal is complete but without advancing the traversal.
+ */
+GtsGNode * gts_graph_traverse_what_next (GtsGraphTraverse * t)
+{
+  g_return_val_if_fail (t != NULL, NULL);
+
+  return gts_fifo_top (t->q);
+}
+
+/**
+ * gts_graph_traverse_destroy:
+ * @t: a #GtsGraphTraverse.
+ *
+ * Frees all the memory allocated for @t.
+ */
+void gts_graph_traverse_destroy (GtsGraphTraverse * t)
+{
+  g_return_if_fail (t != NULL);
+
+  gts_fifo_destroy (t->q);
+  g_free (t);
+}
+
+static void edge_foreach_node (GtsGNode * n, gpointer * info)
+{
+  GtsFunc func = (GtsFunc) info[0];
+  gpointer data = info[1];
+  GHashTable * hash = info[2];
+  GSList * i = GTS_SLIST_CONTAINER (n)->items;
+
+  while (i) {
+    GtsGEdge * e = i->data;
+    if (!g_hash_table_lookup (hash, e)) {
+      (* func) (e, data);
+      g_hash_table_insert (hash, e, e);
+    }
+    i = i->next;
+  }  
+}
+
+/**
+ * gts_graph_foreach_edge:
+ * @g: a #GtsGraph.
+ * @func: a #GtsFunc.
+ * @data: user data to be passed to @func.
+ *
+ * Calls @func for each #GtsEdge of @g.
+ */
+void gts_graph_foreach_edge (GtsGraph * g, GtsFunc func, gpointer data)
+{
+  gpointer info[3];
+  GHashTable * hash;
+
+  g_return_if_fail (g != NULL);
+  g_return_if_fail (func != NULL);
+
+  info[0] = func;
+  info[1] = data;
+  info[2] = hash = g_hash_table_new (NULL, NULL);
+  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) edge_foreach_node, info);
+  g_hash_table_destroy (hash);
+}
+
+/**
+ * gts_graph_weight:
+ * @g: a #GtsGraph.
+ *
+ * Returns: the weight of graph @g as defined by the weight() method
+ * of #GtsGraphClass. 
+ */
+gfloat gts_graph_weight (GtsGraph * g)
+{
+  g_return_val_if_fail (g != NULL, 0.);
+
+  if (GTS_GRAPH_CLASS (GTS_OBJECT (g)->klass)->weight)
+    return (* GTS_GRAPH_CLASS (GTS_OBJECT (g)->klass)->weight) (g);
+  return (gfloat) gts_container_size (GTS_CONTAINER (g));
+}
+
+/**
+ * gts_graph_distance_sum:
+ * @g: a #GtsGraph.
+ * @center: a #GtsGNode of @g.
+ *
+ * Returns: the sum of the distances between all the other #GtsGNode
+ * of @g and @center.  
+ */
+guint gts_graph_distance_sum (GtsGraph * g, GtsGNode * center)
+{
+  GtsGraphTraverse * t;
+  GtsGNode * n;
+  guint sum = 0;
+
+  g_return_val_if_fail (g != NULL, 0);
+  g_return_val_if_fail (center != NULL, 0);
+
+  t = gts_graph_traverse_new (g, center, GTS_BREADTH_FIRST, TRUE);
+  while ((n = gts_graph_traverse_next (t)))
+    sum += n->level - 1;
+  gts_graph_traverse_destroy (t);
+
+  return sum;
+}
+
+/**
+ * gts_graph_farthest:
+ * @g: a #GtsGraph.
+ * @gnodes: a list of #GtsGNode belonging to @g.
+ *
+ * Returns: the #GtsGNode belonging to @g and farthest from all the nodes in
+ * @gnodes (hmmm, definition of "farthest"?).
+ */
+GtsGNode * gts_graph_farthest (GtsGraph * g, GSList * gnodes)
+{
+  GtsGNode * farthest = NULL;
+  GSList * i;
+  gboolean reinit = TRUE, changed = TRUE;
+  guint level = 1;
+
+  g_return_val_if_fail (g != NULL, NULL);
+
+  /* initialize traversals */
+  i = gnodes;
+  while (i) {
+    GTS_OBJECT (i->data)->reserved = 
+      gts_graph_traverse_new (g, i->data, GTS_BREADTH_FIRST, reinit);
+    reinit = FALSE;
+    i = i->next;
+  }
+
+  while (changed) {
+    changed = FALSE;
+    i = gnodes;
+    while (i) {
+      GtsGraphTraverse * t = GTS_OBJECT (i->data)->reserved;
+      GtsGNode * n;
+      while ((n = gts_graph_traverse_what_next (t)) && n->level == level) {
+	changed = TRUE;
+	farthest = n;
+	gts_graph_traverse_next (t);
+      }
+      i = i->next;
+    }
+    level++;
+  }
+
+  /* destroy traversals */
+  i = gnodes;
+  while (i) {
+    gts_graph_traverse_destroy (GTS_OBJECT (i->data)->reserved);
+    GTS_OBJECT (i->data)->reserved = NULL;
+    i = i->next;
+  }
+  return farthest;
+}
+
+static void neighbor_count (GtsGNode * n, gpointer * data)
+{
+  guint * cuts = data[0];
+  GtsGraph * g = data[1];
+  
+  if (!gts_containee_is_contained (GTS_CONTAINEE (n), GTS_CONTAINER (g)))
+    (*cuts)++;
+}
+
+static void count_edge_cuts (GtsGNode * n, gpointer * data)
+{
+  gts_gnode_foreach_neighbor (n, NULL, (GtsFunc) neighbor_count, data);
+}
+
+/**
+ * gts_graph_edges_cut:
+ * @g: a #GtsGraph.
+ *
+ * Returns: the number of edges of @g connecting nodes belonging to @g
+ * to nodes not belonging to @g.  
+ */
+guint gts_graph_edges_cut (GtsGraph * g)
+{
+  guint cuts = 0;
+  gpointer data[2];
+
+  g_return_val_if_fail (g != NULL, 0);
+
+  data[0] = &cuts;
+  data[1] = g;
+  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) count_edge_cuts, data);
+
+  return cuts;
+}
+
+static void sum_edge_cuts_weight (GtsGNode * n, gpointer * data)
+{
+  gfloat * weight = data[0];
+  GtsGraph * g = data[1];
+  GSList * i = GTS_SLIST_CONTAINER (n)->items;
+
+  while (i) {
+    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
+    if (!gts_containee_is_contained (GTS_CONTAINEE (n1), GTS_CONTAINER (g)))
+      *weight += gts_gedge_weight (i->data);
+    i = i->next;
+  }
+}
+
+/**
+ * gts_graph_edges_cut_weight:
+ * @g: a #GtsGraph.
+ *
+ * Returns: the sum of the weights of the edges of @g connecting nodes
+ * belonging to @g to nodes not belonging to @g.
+ */
+gfloat gts_graph_edges_cut_weight (GtsGraph * g)
+{
+  gfloat weight = 0.;
+  gpointer data[2];
+
+  g_return_val_if_fail (g != NULL, 0);
+
+  data[0] = &weight;
+  data[1] = g;
+  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) sum_edge_cuts_weight, 
+			 data);
+
+  return weight;
+}
+
+/**
+ * gts_graph_read_jostle:
+ * @g: a #GtsGraph.
+ * @fp: a #GtsFile.
+ *
+ * Adds to @g the nodes and edges defined in the file pointed to by
+ * @fp. This file must use the Jostle "graph" ASCII format.  
+ * The nodes created are of type #GtsNGNode and their identities are the
+ * line number at which they appear in @fp.
+ *
+ * Returns: 0 if the lecture was successful, the line number at which
+ * an error occured otherwise (in which case the @error field of @fp
+ * is set).  
+ */
+guint gts_graph_read_jostle (GtsGraph * g, GtsFile * fp)
+{
+  guint nn, ne, n;
+  GtsGNode ** nodes;
+
+  g_return_val_if_fail (g != NULL, 1);
+  g_return_val_if_fail (fp != NULL, 1);
+
+  if (fp->type != GTS_INT) {
+    gts_file_error (fp, "expecting an integer (number of nodes)");
+    return fp->line;
+  }
+  nn = atoi (fp->token->str);
+  gts_file_next_token (fp);
+
+  if (fp->type != GTS_INT) {
+    gts_file_error (fp, "expecting an integer (number of edges)");
+    return fp->line;
+  }
+  ne = atoi (fp->token->str);
+
+  gts_file_first_token_after (fp, '\n');
+  nodes = g_malloc (sizeof (GtsGNode *)*(nn + 1));
+
+  n = 0;
+  while (n < nn && fp->type != GTS_ERROR) {
+    GtsNGNode * node = gts_ngnode_new (gts_ngnode_class (), fp->line);
+    
+    nodes[n++] = GTS_GNODE (node);
+    gts_container_add (GTS_CONTAINER (g), GTS_CONTAINEE (node));
+    do {
+      if (fp->type != GTS_INT)
+	gts_file_error (fp, "expecting an integer (node index)");
+      else {
+	guint in = atoi (fp->token->str);
+	
+	if (in == 0 || in > nn)
+	  gts_file_error (fp, "node index `%d' is out of range `[1,%d]'",
+			  in, nn);
+	else if (in == n)
+	  gts_file_error (fp, "node index `%d' references itself", in);
+	else if (in < n) {
+	  gts_gedge_new (g->edge_class, GTS_GNODE (node), nodes[in - 1]);
+	  ne--;
+	  gts_file_next_token (fp);
+	}
+      }
+    } while (fp->type != GTS_ERROR && fp->type != '\n');
+  }
+  g_free (nodes);
+
+  if (fp->type != GTS_ERROR) {
+    if (n != nn)
+      gts_file_error (fp, "only `%d' nodes read out of `%d'",
+		      n, nn);
+    else if (ne > 0)
+      gts_file_error (fp, "`%d' unallocated edges remaining",
+		      ne);
+  }
+
+  if (fp->type == GTS_ERROR)
+    return fp->line;
+  return 0;
+}
+
+static void count_edges (GtsGEdge * e, guint * nedge)
+{
+  (*nedge)++;
+}
+
+static void write_node (GtsObject * node, gpointer * data)
+{
+  FILE * fp = data[0];
+  guint * nnode = data[1];
+
+  node->reserved = GUINT_TO_POINTER ((*nnode)++);
+  if (node->klass->write)
+    (* node->klass->write) (node, fp);
+  fputc ('\n', fp);
+}
+
+static void write_edge (GtsGEdge * edge, FILE * fp)
+{
+  fprintf (fp, "%u %u", 
+	   GPOINTER_TO_UINT (GTS_OBJECT (edge->n1)->reserved),
+	   GPOINTER_TO_UINT (GTS_OBJECT (edge->n2)->reserved));
+  if (GTS_OBJECT (edge)->klass->write)
+    (* GTS_OBJECT (edge)->klass->write) (GTS_OBJECT (edge), fp);
+  fputc ('\n', fp);
+}
+
+/**
+ * gts_graph_write:
+ * @g: a #GtsGraph.
+ * @fp: a file pointer.
+ *
+ * Writes in the file @fp an ASCII representation of @g. The file
+ * format is as follows. 
+ *
+ * All the lines beginning with #GTS_COMMENTS are ignored. The first line
+ * contains two unsigned integers separated by spaces. The first
+ * integer is the number of nodes, nn, the second is the number of
+ * edges, ne.
+ *
+ * Follows nn lines containing node description.
+ * Follows ne lines containing the two indices (starting
+ * from one) of the nodes of each edge.
+ *
+ * The format described above is the least common denominator to all
+ * GTS files.  Consistent with an object-oriented approach, the GTS
+ * file format is extensible. Each of the lines of the file can be
+ * extended with user-specific attributes accessible through the
+ * read() and write() virtual methods of each of the objects written
+ * (graph, nodes or edges). When read with different object classes,
+ * these extra attributes are just ignored.  
+ */
+void gts_graph_write (GtsGraph * g, FILE * fp)
+{
+  guint nnode = 1, nedge = 0;
+  gpointer data[2];
+
+  g_return_if_fail (g != NULL);
+  g_return_if_fail (fp != NULL);
+
+  gts_graph_foreach_edge (g, (GtsFunc) count_edges, &nedge);
+  fprintf (fp, "%u %u", gts_container_size (GTS_CONTAINER (g)), nedge);
+  if (GTS_OBJECT (g)->klass->write)
+    (* GTS_OBJECT (g)->klass->write) (GTS_OBJECT (g), fp);
+  fputc ('\n', fp);
+  data[0] = fp;
+  data[1] = &nnode;
+  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) write_node, data);
+  gts_graph_foreach_edge (g, (GtsFunc) write_edge, fp);
+  gts_container_foreach (GTS_CONTAINER (g), 
+			 (GtsFunc) gts_object_reset_reserved, NULL);
+}
+
+/**
+ * gts_graph_read:
+ * @fp: a #GtsFile.
+ *
+ * Reads a graph from a file.
+ *
+ * Returns: the new #GtsGraph or %NULL if an error occured (in which
+ * case the @error field of @fp is set).
+ */
+GtsGraph * gts_graph_read (GtsFile * fp)
+{
+  GtsGraph * g;
+  GtsGNode ** nodes;
+  guint nn, ne, n;
+
+  g_return_val_if_fail (fp != NULL, NULL);
+
+  if (fp->type != GTS_INT) {
+    gts_file_error (fp, "expecting an integer (number of nodes)");
+    return NULL;
+  }
+  nn = atoi (fp->token->str);
+  gts_file_next_token (fp);
+
+  if (fp->type != GTS_INT) {
+    gts_file_error (fp, "expecting an integer (number of edges)");
+    return NULL;
+  }
+  ne = atoi (fp->token->str);
+
+  gts_file_next_token (fp);
+  if (fp->type != '\n') {
+    GtsObjectClass * klass;
+
+    gts_graph_class ();
+    gts_gnode_class ();
+    gts_gedge_class ();
+
+    if (fp->type != GTS_STRING) {
+      gts_file_error (fp, "expecting a string (GtsGraphClass)");
+      return NULL;
+    }
+    klass = gts_object_class_from_name (fp->token->str);
+    if (klass == NULL) {
+      gts_file_error (fp, "unknown class `%s'", fp->token->str);
+      return NULL;
+    }
+    if (!gts_object_class_is_from_class (klass, gts_graph_class ())) {
+      gts_file_error (fp, "class `%s' is not a GtsGraphClass", fp->token->str);
+      return NULL;
+    }
+    g = GTS_GRAPH (gts_object_new (klass));
+    g->graph_class = GTS_GRAPH_CLASS (klass);
+    gts_file_next_token (fp);
+    (* klass->read) ((GtsObject **) &g, fp);
+    if (fp->type == GTS_ERROR) {
+      gts_object_destroy (GTS_OBJECT (g));
+      return NULL;
+    }
+  }
+  else
+    g = GTS_GRAPH (gts_object_new (GTS_OBJECT_CLASS (gts_graph_class ())));
+  gts_file_first_token_after (fp, '\n');
+  if (nn <= 0)
+    return g;
+
+  nodes = g_malloc ((nn + 1)*sizeof (GtsGNode *));
+
+  n = 0;
+  while (n < nn && fp->type != GTS_ERROR) {
+    GtsObject * new_node = 
+      gts_object_new (GTS_OBJECT_CLASS (g->node_class));
+
+    gts_container_add (GTS_CONTAINER (g), GTS_CONTAINEE (new_node));
+    if (GTS_OBJECT_CLASS (g->node_class)->read)
+      (*GTS_OBJECT_CLASS (g->node_class)->read) (&new_node, fp);
+    gts_file_first_token_after (fp, '\n');
+    nodes[n++] = GTS_GNODE (new_node);
+  }
+  if (fp->type == GTS_ERROR)
+    nn = n;
+
+  n = 0;
+  while (n < ne && fp->type != GTS_ERROR) {
+    guint n1, n2;
+
+    if (fp->type != GTS_INT)
+      gts_file_error (fp, "expecting an integer (first node index)");
+    else {
+      n1 = atoi (fp->token->str);
+      if (n1 == 0 || n1 > nn)
+	gts_file_error (fp, "node index `%d' is out of range `[1,%d]'",
+			n1, nn);
+      else {
+	gts_file_next_token (fp);
+	if (fp->type != GTS_INT)
+	  gts_file_error (fp, "expecting an integer (second node index)");
+	else {
+	  n2 = atoi (fp->token->str);
+	  if (n2 == 0 || n2 > nn)
+	    gts_file_error (fp, "node index `%d' is out of range `[1,%d]'",
+			    n2, nn);
+	  else {
+	    GtsGEdge * new_edge =
+	      gts_gedge_new (g->edge_class, nodes[n1 - 1], nodes [n2 - 1]);
+
+	    gts_file_next_token (fp);
+	    if (fp->type != '\n')
+	      if (GTS_OBJECT_CLASS (g->edge_class)->read)
+		(*GTS_OBJECT_CLASS (g->edge_class)->read)
+		  ((GtsObject **) &new_edge, fp);
+	    gts_file_first_token_after (fp, '\n');
+	    n++;
+	  }
+	}
+      }
+    }
+  }
+
+  if (fp->type == GTS_ERROR) {
+    gts_allow_floating_gnodes = TRUE;
+    while (nn)
+      gts_object_destroy (GTS_OBJECT (nodes[nn-- - 1]));
+    gts_allow_floating_gnodes = FALSE;
+  }
+  g_free (nodes);
+
+  if (fp->type == GTS_ERROR) {
+    gts_object_destroy (GTS_OBJECT (g));
+    return NULL;
+  }
+  return g;
+}
+
+static void write_dot_node (GtsGNode * node, gpointer * data)
+{
+  FILE * fp = data[0];
+  guint * nnode = data[1];
+
+  fprintf (fp, "  n%u", *nnode);
+  if (GTS_GNODE_CLASS (GTS_OBJECT (node)->klass)->write) {
+    fputs (" [", fp);
+    (* GTS_GNODE_CLASS (GTS_OBJECT (node)->klass)->write) (node, fp);
+    fputc (']', fp);
+  }
+  fputs (";\n", fp);
+  GTS_OBJECT (node)->reserved = GUINT_TO_POINTER ((*nnode)++);  
+}
+
+static void write_dot_edge (GtsGEdge * edge, FILE * fp)
+{
+  fprintf (fp, "  n%u -> n%u", 
+	   GPOINTER_TO_UINT (GTS_OBJECT (edge->n1)->reserved),
+	   GPOINTER_TO_UINT (GTS_OBJECT (edge->n2)->reserved));
+  if (GTS_GEDGE_CLASS (GTS_OBJECT (edge)->klass)->write) {
+    fputs (" [", fp);
+    (* GTS_GEDGE_CLASS (GTS_OBJECT (edge)->klass)->write) (edge, fp);
+    fputc (']', fp);
+  }
+  fputs (";\n", fp);
+}
+
+/**
+ * gts_graph_write_dot:
+ * @g: a #GtsGraph.
+ * @fp: a file pointer.
+ *
+ * Writes in the file @fp an ASCII representation of @g in the dot format of
+ * AT&T Bell Labs.
+ */
+void gts_graph_write_dot (GtsGraph * g, FILE * fp)
+{
+  guint nnode = 1;
+  gpointer data[2];
+
+  g_return_if_fail (g != NULL);
+  g_return_if_fail (fp != NULL);
+
+  fprintf (fp, "digraph \"%p\" {\n", g);
+  data[0] = fp;
+  data[1] = &nnode;
+  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) write_dot_node, data);
+  gts_graph_foreach_edge (g, (GtsFunc) write_dot_edge, fp);
+  fputs ("}\n", fp);
+
+  gts_container_foreach (GTS_CONTAINER (g), 
+			 (GtsFunc) gts_object_reset_reserved, NULL);
+}
+
+/* GtsWGraph */
+
+static gfloat wgraph_weight (GtsGraph * g)
+{
+  return GTS_WGRAPH (g)->weight;
+}
+
+static void wgraph_add (GtsContainer * g, GtsContainee * n)
+{
+  GtsWGraph * wg = GTS_WGRAPH (g);
+  gfloat w = gts_gnode_weight (GTS_GNODE (n));
+
+  wg->weight += w;
+  
+  (* GTS_CONTAINER_CLASS (GTS_OBJECT_CLASS (gts_wgraph_class ())->parent_class)->add) (g, n);
+}
+
+static void wgraph_remove (GtsContainer * g, GtsContainee * n)
+{
+  GTS_WGRAPH (g)->weight -= gts_gnode_weight (GTS_GNODE (n));
+  
+  (* GTS_CONTAINER_CLASS (GTS_OBJECT_CLASS (gts_wgraph_class ())->parent_class)->remove) (g, n);
+}
+
+static void wgraph_class_init (GtsWGraphClass * klass)
+{
+  GTS_GRAPH_CLASS (klass)->weight = wgraph_weight;
+
+  GTS_CONTAINER_CLASS (klass)->add = wgraph_add;
+  GTS_CONTAINER_CLASS (klass)->remove = wgraph_remove;
+}
+
+static void wgraph_init (GtsWGraph * g)
+{
+  g->weight = 0.;
+}
+
+/**
+ * gts_wgraph_class:
+ *
+ * Returns: the #GtsWGraphClass.
+ */
+GtsWGraphClass * gts_wgraph_class (void)
+{
+  static GtsWGraphClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo wgraph_info = {
+      "GtsWGraph",
+      sizeof (GtsWGraph),
+      sizeof (GtsWGraphClass),
+      (GtsObjectClassInitFunc) wgraph_class_init,
+      (GtsObjectInitFunc) wgraph_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_graph_class ()),
+				  &wgraph_info);
+  }
+
+  return klass;
+}
+
+static void weight_max (GtsGNode * n, gfloat * wmax)
+{
+  gfloat w = gts_gnode_weight (n);
+
+  if (w > *wmax)
+    *wmax = w;
+}
+
+/**
+ * gts_wgraph_weight_max:
+ * @wg: a #GtsWGraph.
+ *
+ * Returns: the maximum weight of any vertices belonging to @g.
+ */
+gfloat gts_wgraph_weight_max (GtsWGraph * wg)
+{
+  gfloat wmax = - G_MAXFLOAT;
+
+  g_return_val_if_fail (wg != NULL, 0.);
+
+  gts_container_foreach (GTS_CONTAINER (wg), (GtsFunc) weight_max, &wmax);
+
+  return wmax;
+}
+
+/* Surface graph */
+
+static void create_node (GtsFace * f, GtsGraph * graph)
+{
+  GtsFNode * fn = gts_fnode_new (gts_fnode_class (), f);
+
+  gts_container_add (GTS_CONTAINER (graph), GTS_CONTAINEE (fn));
+  GTS_OBJECT (f)->reserved = fn;
+}
+
+static void create_edge (GtsEdge * e, GtsSurface * s)
+{
+  GSList * i = e->triangles;
+  
+  while (i) {
+    GtsFace * f = i->data;
+    if (GTS_IS_FACE (f) && gts_face_has_parent_surface (f, s)) {
+      GSList * j = i->next;
+      while (j) {
+	GtsFace * f1 = j->data;
+	if (GTS_IS_FACE (f1) && gts_face_has_parent_surface (f1, s))
+	  gts_pgedge_new (gts_pgedge_class (), 
+			  GTS_OBJECT (f)->reserved,
+			  GTS_OBJECT (f1)->reserved,
+			  e);
+	j = j->next;
+      }
+    }
+    i = i->next;
+  }
+}
+
+/**
+ * gts_surface_graph_new:
+ * @klass: a #GtsGraphClass.
+ * @s: a #GtsSurface.
+ *
+ * Returns: a new #GtsGraph representing the connectivity of the faces
+ * of @s. This graph uses #GtsFGNode as nodes which allows to store
+ * the dependencies between nodes and faces of @s.  
+ */
+GtsGraph * gts_surface_graph_new (GtsGraphClass * klass,
+				  GtsSurface * s)
+{
+  GtsGraph * graph;
+  
+  g_return_val_if_fail (klass != NULL, NULL);
+  g_return_val_if_fail (s != NULL, NULL);
+
+  graph = GTS_GRAPH (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  gts_surface_foreach_face (s, (GtsFunc) create_node, graph);
+  gts_surface_foreach_edge (s, (GtsFunc) create_edge, s);
+  gts_surface_foreach_face (s, (GtsFunc) gts_object_reset_reserved, NULL);
+
+  return graph;
+}
+
+static void create_segment_edge (GtsSegment * s, GtsGraph * graph)
+{
+  GtsGNode * n1 = GTS_OBJECT (s->v1)->reserved, * n2;
+
+  if (n1 == NULL) {
+    n1 = GTS_GNODE (gts_pnode_new (gts_pnode_class (), s->v1));
+    gts_container_add (GTS_CONTAINER (graph), GTS_CONTAINEE (n1));
+    GTS_OBJECT (s->v1)->reserved = n1;
+  }
+
+  n2 = GTS_OBJECT (s->v2)->reserved;
+  if (n2 == NULL) {
+    n2 = GTS_GNODE (gts_pnode_new (gts_pnode_class (), s->v2));
+    gts_container_add (GTS_CONTAINER (graph), GTS_CONTAINEE (n2));
+    GTS_OBJECT (s->v2)->reserved = n2;
+  }
+  
+  gts_pgedge_new (gts_pgedge_class (), n1, n2, s);
+}
+
+static void reset_reserved (GtsSegment * s)
+{
+  GTS_OBJECT (s->v1)->reserved = GTS_OBJECT (s->v2)->reserved = NULL;
+}
+
+/**
+ * gts_segments_graph_new:
+ * @klass: a #GtsGraphClass.
+ * @segments: a list of #GtsSegment.
+ *
+ * Returns: a new #GtsGraph representing the connectivity of the segments
+ * in @segments.
+ */
+GtsGraph * gts_segments_graph_new (GtsGraphClass * klass,
+				   GSList * segments)
+{
+  GtsGraph * graph;
+  
+  g_return_val_if_fail (klass != NULL, NULL);
+
+  graph = GTS_GRAPH (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  g_slist_foreach (segments, (GFunc) create_segment_edge, graph);
+  g_slist_foreach (segments, (GFunc) reset_reserved, NULL);
+
+  return graph;
+}
+
+static void add_to_surface (GtsGNode * n, GtsSurface * s)
+{
+  if (GTS_IS_FNODE (n))
+    gts_surface_add_face (s, GTS_FNODE (n)->f);
+}
+
+/**
+ * gts_surface_graph_surface:
+ * @surface_graph: a #GtsGraph using #GtsFGNode as nodes.
+ * @s: a #GtsSurface.
+ *
+ * Returns: a new #GtsSurface using the same classes as @s and
+ * composed of the faces defined by @surface_graph.
+ */
+GtsSurface * gts_surface_graph_surface (GtsGraph * surface_graph,
+					GtsSurface * s)
+{
+  GtsSurface * s1;
+
+  g_return_val_if_fail (surface_graph != NULL, NULL);
+  g_return_val_if_fail (s != NULL, NULL);
+  
+  s1 = gts_surface_new (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass),
+			s->face_class,
+			s->edge_class,
+			s->vertex_class);
+  gts_container_foreach (GTS_CONTAINER (surface_graph), 
+			 (GtsFunc) add_to_surface, s1);
+  return s1;
+}
+
diff --git a/gts/gts-private.h b/gts/gts-private.h
new file mode 100644
index 0000000..59246d1
--- /dev/null
+++ b/gts/gts-private.h
@@ -0,0 +1,37 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef __GTS_PRIVATE_H__
+#define __GTS_PRIVATE_H__
+
+/* Debugging flags */
+  
+/* #define DEBUG_FUNCTIONS */
+
+#ifdef DEBUG_FUNCTIONS
+/* #define DEBUG_LEAKS */
+#define DEBUG_IDENTITY
+guint id (gpointer p);
+void id_insert (gpointer p);
+void id_remove (gpointer p);
+void gts_write_triangle (GtsTriangle * t, GtsPoint * o, FILE * fptr);
+void gts_write_segment (GtsSegment * s, GtsPoint * o, FILE * fptr);
+#endif /* DEBUG_FUNCTIONS */
+
+#endif /* __GTS_PRIVATE_H__ */
diff --git a/gts/gts.h b/gts/gts.h
new file mode 100644
index 0000000..9397230
--- /dev/null
+++ b/gts/gts.h
@@ -0,0 +1,2577 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef __GTS_H__
+#define __GTS_H__
+
+#include <stdio.h>
+#include <glib.h>
+
+#define GTS_MAJOR_VERSION 0
+#define GTS_MINOR_VERSION 7
+#define GTS_MICRO_VERSION 6
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+/* Added based on glib.h by M J Loehr 01/01/01 */
+/* GTS version.
+ * we prefix variable declarations so they can
+ * properly get exported in windows dlls.
+ */
+#ifdef NATIVE_WIN32
+#  ifdef GTS_COMPILATION
+#    define GTS_C_VAR __declspec(dllexport)
+#  else /* not GTS_COMPILATION */
+#    define GTS_C_VAR extern __declspec(dllimport)
+#  endif /* not GTS_COMPILATION */
+#else /* not NATIVE_WIN32 */
+#  define GTS_C_VAR extern
+#endif /* not NATIVE_WIN32 */
+
+GTS_C_VAR const guint gts_major_version;
+GTS_C_VAR const guint gts_minor_version;
+GTS_C_VAR const guint gts_micro_version;
+GTS_C_VAR const guint gts_interface_age;
+GTS_C_VAR const guint gts_binary_age;
+
+#define GTS_CHECK_VERSION(major,minor,micro)    \
+    (gts_major_version > (major) || \
+    (gts_major_version == (major) && gts_minor_version > (minor)) || \
+    (gts_major_version == (major) && gts_minor_version == (minor) && \
+     gts_micro_version >= (micro)))
+
+#define GTS_COMMENTS  "#!"
+#define GTS_MAINTAINER "popinet@xxxxxxxxxxxxxxxxxxxxx"
+
+
+
+
+void gts_predicates_init();
+
+
+/* Class declarations for base types */
+
+typedef struct _GtsObjectClassInfo     GtsObjectClassInfo;
+typedef struct _GtsObject        GtsObject;
+typedef struct _GtsObjectClass   GtsObjectClass;
+typedef struct _GtsPoint         GtsPoint;
+typedef struct _GtsPointClass    GtsPointClass;
+typedef struct _GtsVertex        GtsVertex;
+typedef struct _GtsVertexClass   GtsVertexClass;
+typedef struct _GtsSegment       GtsSegment;
+typedef struct _GtsSegmentClass  GtsSegmentClass;
+typedef struct _GtsEdge          GtsEdge;
+typedef struct _GtsEdgeClass     GtsEdgeClass;
+typedef struct _GtsTriangle      GtsTriangle;
+typedef struct _GtsTriangleClass GtsTriangleClass;
+typedef struct _GtsFace          GtsFace;
+typedef struct _GtsFaceClass     GtsFaceClass;
+typedef struct _GtsBBox          GtsBBox;
+typedef struct _GtsBBoxClass     GtsBBoxClass;
+typedef struct _GtsSurface       GtsSurface;
+typedef struct _GtsSurfaceClass  GtsSurfaceClass;
+
+typedef void         (*GtsObjectClassInitFunc) (GtsObjectClass * objclass);
+typedef void         (*GtsObjectInitFunc)      (GtsObject * obj);
+typedef void         (*GtsArgSetFunc)          (GtsObject * obj);
+typedef void         (*GtsArgGetFunc)          (GtsObject * obj);
+
+typedef gdouble                  GtsVector[3];
+typedef gdouble                  GtsVector4[4];
+typedef GtsVector4               GtsMatrix;
+/**
+ * GtsKeyFunc:
+ * @item: A pointer to an item to be stored in the heap.
+ * @data: User data passed to gts_eheap_new().
+ *
+ * Returns: the value of the key for the given item.
+ */
+typedef gdouble                  (*GtsKeyFunc)    (gpointer item,
+						   gpointer data);
+typedef enum 
+{ 
+  GTS_OUT = -1,
+  GTS_ON = 0,
+  GTS_IN = 1
+} GtsIntersect;
+
+typedef struct _GtsColor         GtsColor;
+
+struct _GtsColor {
+  gfloat r, g, b;
+};
+
+typedef gint   (*GtsFunc)              (gpointer item,
+					gpointer data);
+
+/* misc.c */
+
+typedef struct _GtsFile GtsFile;
+
+typedef enum {
+  GTS_NONE   = 1 << 8,
+  GTS_INT    = 1 << 9,
+  GTS_UINT   = 1 << 10,
+  GTS_FLOAT  = 1 << 11,
+  GTS_DOUBLE = 1 << 12,
+  GTS_STRING = 1 << 13,
+  GTS_FILE   = 1 << 14,
+  GTS_ERROR  = 1 << 15
+} GtsTokenType;
+
+struct _GtsFile {
+  FILE * fp;
+  gchar * s, * s1;
+  guint line, pos;
+  GString * token;
+  GtsTokenType type;
+  gchar * error;
+
+  guint curline, curpos;
+  guint scope, scope_max;
+  gint next_token;
+  gchar * delimiters;
+  gchar * comments;
+  gchar * tokens;
+};
+
+typedef struct _GtsFileVariable GtsFileVariable;
+
+struct _GtsFileVariable {
+  GtsTokenType type;
+  gchar name[30];
+  gboolean unique;
+  gpointer data;
+  gboolean set;
+  guint line, pos;
+};
+
+
+GtsFile *      gts_file_new               (FILE * fp);
+GtsFile *      gts_file_new_from_string   (const gchar * s);
+void           gts_file_verror            (GtsFile * f,
+					   const gchar * format,
+					   va_list args);
+void           gts_file_error             (GtsFile * f,
+					   const gchar * format,
+					   ...);
+gint           gts_file_getc              (GtsFile * f);
+guint          gts_file_read              (GtsFile * f, 
+					   gpointer ptr, 
+					   guint size, 
+					   guint nmemb);
+gint           gts_file_getc_scope        (GtsFile * f);
+void           gts_file_next_token        (GtsFile * f);
+void           gts_file_first_token_after (GtsFile * f, 
+					   GtsTokenType type);
+void           gts_file_assign_start      (GtsFile * f, 
+					   GtsFileVariable * vars);
+GtsFileVariable * gts_file_assign_next    (GtsFile * f, 
+					   GtsFileVariable * vars);
+void           gts_file_assign_variables  (GtsFile * f, 
+					   GtsFileVariable * vars);
+void           gts_file_variable_error    (GtsFile * f, 
+					   GtsFileVariable * vars,
+					   const gchar * name,
+					   const gchar * format,
+					   ...);
+void           gts_file_destroy           (GtsFile * f);
+
+/* Objects: object.c */
+
+#ifdef GTS_CHECK_CASTS
+#  define GTS_OBJECT_CAST(obj, type, klass) ((type *) gts_object_check_cast (obj, klass))
+#  define GTS_OBJECT_CLASS_CAST(objklass, type, klass) ((type *) gts_object_class_check_cast (objklass, klass))
+#else  /* not GTS_CHECK_CASTS */
+#  define GTS_OBJECT_CAST(obj, type, klass)             ((type *) (obj))
+#  define GTS_OBJECT_CLASS_CAST(objklass, type, klass)  ((type *) (objklass))
+#endif /* not GTS_CHECK_CASTS */
+
+#define GTS_CLASS_NAME_LENGTH 40
+#define GTS_OBJECT(obj)          GTS_OBJECT_CAST (obj,\
+						  GtsObject,\
+						  gts_object_class ())
+#define GTS_OBJECT_CLASS(klass)  GTS_OBJECT_CLASS_CAST (klass,\
+							GtsObjectClass,\
+							gts_object_class())
+#define GTS_IS_OBJECT(obj) (gts_object_is_from_class (obj,\
+						      gts_object_class ()))
+
+typedef enum
+{
+  GTS_DESTROYED         = 1 << 0,
+  GTS_USER_FLAG         = 1 /* user flags start from here */
+} GtsObjectFlags;
+
+#define GTS_OBJECT_FLAGS(obj)             (GTS_OBJECT (obj)->flags)
+#define GTS_OBJECT_DESTROYED(obj)         ((GTS_OBJECT_FLAGS (obj) & GTS_DESTROYED) != 0)
+#define GTS_OBJECT_SET_FLAGS(obj,flag)	  G_STMT_START{ (GTS_OBJECT_FLAGS (obj) |= (flag)); }G_STMT_END
+#define GTS_OBJECT_UNSET_FLAGS(obj,flag)  G_STMT_START{ (GTS_OBJECT_FLAGS (obj) &= ~(flag)); }G_STMT_END
+
+struct _GtsObjectClassInfo {
+  gchar name[GTS_CLASS_NAME_LENGTH];
+  guint object_size;
+  guint class_size;
+  GtsObjectClassInitFunc class_init_func;
+  GtsObjectInitFunc object_init_func;
+  GtsArgSetFunc arg_set_func;
+  GtsArgGetFunc arg_get_func;
+};
+
+struct _GtsObject {
+  GtsObjectClass * klass;
+
+  gpointer reserved;
+  guint32 flags;
+};
+
+struct _GtsObjectClass {
+  GtsObjectClassInfo info;
+  GtsObjectClass * parent_class;
+
+  void        (* clone)      (GtsObject *, GtsObject *);
+  void        (* destroy)    (GtsObject *);
+  void        (* read)       (GtsObject **, GtsFile *);
+  void        (* write)      (GtsObject *, FILE *);
+  GtsColor    (* color)      (GtsObject *);
+  void        (* attributes) (GtsObject *, GtsObject *);
+};
+
+gpointer         gts_object_class_new      (GtsObjectClass * parent_class,
+					    GtsObjectClassInfo * info);
+GtsObjectClass * gts_object_class          (void);
+gpointer         gts_object_check_cast     (gpointer object, 
+					    gpointer klass);
+gpointer         gts_object_class_check_cast (gpointer klass, 
+					      gpointer from);
+
+static inline
+gpointer gts_object_is_from_class (gpointer object,
+				   gpointer klass)
+{
+  GtsObjectClass * c;
+
+  g_return_val_if_fail (klass != NULL, NULL);
+
+  if (object == NULL)
+    return NULL;
+
+  c = ((GtsObject *) object)->klass;
+
+  g_return_val_if_fail (c != NULL, NULL);
+
+  while (c) {
+    if (c == klass)
+      return object;
+    c = c->parent_class;
+  }
+
+  return NULL;
+}
+
+static inline
+gpointer gts_object_class_is_from_class (gpointer klass,
+					 gpointer from)
+{
+  GtsObjectClass * c;
+
+  g_return_val_if_fail (klass != NULL, NULL);
+  g_return_val_if_fail (from != NULL, NULL);
+
+  c = (GtsObjectClass *) klass;
+  while (c) {
+    if (c == from)
+      return klass;
+    c = c->parent_class;
+  }
+
+  return NULL;
+}
+
+GtsObjectClass * gts_object_class_from_name     (const gchar * name);
+
+GtsObject *      gts_object_new                 (GtsObjectClass * klass);
+GtsObject *      gts_object_clone               (GtsObject * object);
+void             gts_object_attributes          (GtsObject * object, 
+						 GtsObject * from);
+void             gts_object_init                (GtsObject * object, 
+						 GtsObjectClass * klass);
+void             gts_object_reset_reserved      (GtsObject * object);
+void             gts_object_destroy             (GtsObject * object);
+void             gts_finalize                   (void);
+
+/* Ranges: surface.c */
+typedef struct _GtsRange               GtsRange;
+
+struct _GtsRange {
+  gdouble min, max, sum, sum2, mean, stddev;
+  guint n;
+};
+
+void gts_range_init         (GtsRange * r);
+void gts_range_reset        (GtsRange * r);
+void gts_range_add_value    (GtsRange * r, 
+			     gdouble val);
+void gts_range_update       (GtsRange * r);
+void gts_range_print        (GtsRange * r, 
+			     FILE * fptr);
+
+/* Points: point.c */
+
+#define GTS_IS_POINT(obj) (gts_object_is_from_class (obj,\
+						     gts_point_class ()))
+#define GTS_POINT(obj)              GTS_OBJECT_CAST (obj,\
+						     GtsPoint,\
+						     gts_point_class ())
+#define GTS_POINT_CLASS(klass)      GTS_OBJECT_CLASS_CAST (klass,\
+							   GtsPointClass,\
+							   gts_point_class ())
+
+struct _GtsPoint {
+  GtsObject object;
+
+  gdouble x, y, z; /* must be contiguous (cast to robust functions) */
+};
+
+struct _GtsPointClass {
+  GtsObjectClass parent_class;
+  gboolean binary;
+};
+
+GtsPointClass * gts_point_class                      (void);
+GtsPoint *    gts_point_new                          (GtsPointClass * klass,
+						      gdouble x, 
+						      gdouble y, 
+						      gdouble z);
+void          gts_point_set                          (GtsPoint * p, 
+						      gdouble x, 
+						      gdouble y, 
+						      gdouble z);
+#define       gts_point_is_in_rectangle(p, p1, p2)   ((p)->x >= (p1)->x &&\
+						      (p)->x <= (p2)->x &&\
+						      (p)->y >= (p1)->y &&\
+						      (p)->y <= (p2)->y &&\
+						      (p)->z >= (p1)->z &&\
+						      (p)->z <= (p2)->z)
+GtsPoint *    gts_segment_triangle_intersection      (GtsSegment * s,
+						      GtsTriangle * t,
+						      gboolean boundary,
+						      GtsPointClass * klass);
+void          gts_point_transform                    (GtsPoint * p, 
+						      GtsMatrix * m);
+gdouble       gts_point_distance                     (GtsPoint * p1,
+						      GtsPoint * p2);
+gdouble       gts_point_distance2                    (GtsPoint * p1,
+						      GtsPoint * p2);
+gdouble       gts_point_orientation_3d               (GtsPoint * p1,
+						      GtsPoint * p2,
+						      GtsPoint * p3,
+						      GtsPoint * p4);
+gint          gts_point_orientation_3d_sos           (GtsPoint * p1,
+						      GtsPoint * p2,
+						      GtsPoint * p3,
+						      GtsPoint * p4);
+GtsIntersect  gts_point_is_in_triangle               (GtsPoint * p,
+						      GtsTriangle * t);
+gdouble       gts_point_in_circle                    (GtsPoint * p, 
+						      GtsPoint * p1,
+						      GtsPoint * p2,
+						      GtsPoint * p3);
+gdouble       gts_point_in_sphere                    (GtsPoint * p, 
+						      GtsPoint * p1,
+						      GtsPoint * p2,
+						      GtsPoint * p3,
+						      GtsPoint * p4);
+gdouble       gts_point_in_triangle_circle           (GtsPoint * p, 
+						      GtsTriangle * t);
+gdouble       gts_point_orientation                  (GtsPoint * p1,
+						      GtsPoint * p2,
+						      GtsPoint * p3);
+gint          gts_point_orientation_sos              (GtsPoint * p1,
+						      GtsPoint * p2,
+						      GtsPoint * p3);
+gdouble       gts_point_segment_distance2            (GtsPoint * p, 
+						      GtsSegment * s);
+gdouble       gts_point_segment_distance             (GtsPoint * p, 
+						      GtsSegment * s);
+void          gts_point_segment_closest              (GtsPoint * p, 
+						      GtsSegment * s,
+						      GtsPoint * closest);
+gdouble       gts_point_triangle_distance2           (GtsPoint * p, 
+						      GtsTriangle * t);
+gdouble       gts_point_triangle_distance            (GtsPoint * p, 
+						      GtsTriangle * t);
+void          gts_point_triangle_closest             (GtsPoint * p,
+						      GtsTriangle * t,
+						      GtsPoint * closest);
+gboolean      gts_point_is_inside_surface            (GtsPoint * p, 
+						      GNode * tree,
+						      gboolean is_open);
+
+/* Vertices: vertex.c */
+
+#define GTS_IS_VERTEX(obj)   (gts_object_is_from_class (obj,\
+							gts_vertex_class ()))
+#define GTS_VERTEX(obj)             GTS_OBJECT_CAST (obj,\
+						     GtsVertex,\
+						     gts_vertex_class ())
+#define GTS_VERTEX_CLASS(klass)     GTS_OBJECT_CLASS_CAST (klass,\
+							   GtsVertexClass,\
+							   gts_vertex_class ())
+struct _GtsVertex {
+  GtsPoint p;
+  
+  GSList * segments;
+};
+
+struct _GtsVertexClass {
+  GtsPointClass parent_class;
+
+  void        (* intersection_attributes) (GtsVertex *, 
+					   GtsObject *, 
+					   GtsObject *);
+};
+
+GTS_C_VAR 
+gboolean      gts_allow_floating_vertices;
+
+GtsVertexClass * gts_vertex_class          (void);
+GtsVertex *   gts_vertex_new               (GtsVertexClass * klass,
+					    gdouble x,
+					    gdouble y,
+					    gdouble z);
+void          gts_vertex_replace           (GtsVertex * v, 
+					    GtsVertex * with);
+gboolean      gts_vertex_is_unattached     (GtsVertex * v);
+GtsSegment *  gts_vertices_are_connected   (GtsVertex * v1,
+					    GtsVertex * v2);
+GSList *      gts_vertex_triangles         (GtsVertex * v,
+					    GSList * list);
+GSList *      gts_vertex_faces             (GtsVertex * v,
+					    GtsSurface * surface,
+					    GSList * list);
+GSList *      gts_vertex_neighbors         (GtsVertex * v, 
+					    GSList * list,
+					    GtsSurface * surface);
+GSList *      gts_vertices_from_segments   (GSList * segments);
+gboolean      gts_vertex_is_boundary       (GtsVertex * v, 
+					    GtsSurface * surface);
+GList *       gts_vertices_merge           (GList * vertices, 
+					    gdouble epsilon,
+					    gboolean (* check) (GtsVertex *, GtsVertex *));
+GSList *      gts_vertex_fan_oriented      (GtsVertex * v, 
+					    GtsSurface * surface);
+guint         gts_vertex_is_contact        (GtsVertex * v, gboolean sever);
+
+/* GtsVertexNormal: Header */
+
+typedef struct _GtsVertexNormal         GtsVertexNormal;
+
+struct _GtsVertexNormal {
+  /*< private >*/
+  GtsVertex parent;
+
+  /*< public >*/
+  GtsVector n;
+};
+
+#define GTS_VERTEX_NORMAL(obj)            GTS_OBJECT_CAST (obj,\
+					         GtsVertexNormal,\
+					         gts_vertex_normal_class ())
+#define GTS_IS_VERTEX_NORMAL(obj)         (gts_object_is_from_class (obj,\
+						 gts_vertex_normal_class ()))
+
+GtsVertexClass * gts_vertex_normal_class  (void);
+
+/* GtsColorVertex: Header */
+
+typedef struct _GtsColorVertex         GtsColorVertex;
+
+struct _GtsColorVertex {
+  /*< private >*/
+  GtsVertex parent;
+
+  /*< public >*/
+  GtsColor c;
+};
+
+#define GTS_COLOR_VERTEX(obj)            GTS_OBJECT_CAST (obj,\
+					         GtsColorVertex,\
+					         gts_color_vertex_class ())
+#define GTS_IS_COLOR_VERTEX(obj)         (gts_object_is_from_class (obj,\
+						 gts_color_vertex_class ()))
+
+GtsVertexClass * gts_color_vertex_class  (void);
+
+/* Segments: segment.c */
+
+#define GTS_IS_SEGMENT(obj) (gts_object_is_from_class (obj,\
+						       gts_segment_class ()))
+#define GTS_SEGMENT(obj)          GTS_OBJECT_CAST (obj,\
+						   GtsSegment,\
+						   gts_segment_class ())
+#define GTS_SEGMENT_CLASS(klass)  GTS_OBJECT_CLASS_CAST (klass,\
+							 GtsSegmentClass,\
+							 gts_segment_class ())
+
+struct _GtsSegment {
+  GtsObject object;
+
+  GtsVertex * v1;
+  GtsVertex * v2;
+};
+
+struct _GtsSegmentClass {
+  GtsObjectClass parent_class;
+};
+
+GtsSegmentClass * gts_segment_class                  (void);
+GtsSegment *  gts_segment_new                        (GtsSegmentClass * klass,
+						      GtsVertex * v1, 
+						      GtsVertex * v2);
+#define       gts_segment_connect(s, e1, e2)         (((s)->v1 == e1 &&\
+                                                       (s)->v2 == e2) || \
+                                                      ((s)->v1 == e2 &&\
+                                                       (s)->v2 == e1))
+#define       gts_segments_are_identical(s1, s2)     (((s1)->v1 == (s2)->v1 &&\
+						       (s1)->v2 == (s2)->v2)\
+						      ||\
+						      ((s1)->v1 == (s2)->v2 &&\
+						       (s1)->v2 == (s2)->v1))
+#define       gts_segments_touch(s1, s2)             ((s1)->v1 == (s2)->v1 ||\
+						      (s1)->v1 == (s2)->v2 ||\
+						      (s1)->v2 == (s2)->v1 ||\
+						      (s1)->v2 == (s2)->v2)
+GtsIntersect  gts_segments_are_intersecting          (GtsSegment * s1,
+						      GtsSegment * s2);
+GtsSegment *  gts_segment_is_duplicate               (GtsSegment * s);
+GtsVertex *   gts_segment_midvertex                  (GtsSegment * s,
+						      GtsVertexClass * klass);
+GSList *      gts_segments_from_vertices             (GSList * vertices);
+gboolean      gts_segment_is_ok                      (GtsSegment * s);
+
+/* Edges: edge.c */
+
+#define GTS_IS_EDGE(obj)  (gts_object_is_from_class (obj,\
+						     gts_edge_class ()))
+#define GTS_EDGE(obj)            GTS_OBJECT_CAST (obj,\
+						  GtsEdge,\
+						  gts_edge_class ())
+#define GTS_EDGE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+							GtsEdgeClass,\
+							gts_edge_class ())
+
+struct _GtsEdge {
+  GtsSegment segment;
+
+  GSList * triangles;
+};
+
+struct _GtsEdgeClass {
+  GtsSegmentClass parent_class;
+};
+
+GTS_C_VAR 
+gboolean      gts_allow_floating_edges;
+
+GtsEdgeClass * gts_edge_class                     (void);
+GtsEdge *     gts_edge_new                        (GtsEdgeClass * klass,
+						   GtsVertex * v1,
+						   GtsVertex * v2);
+/**
+ * gts_edge_is_unattached:
+ * @s: a #GtsEdge.
+ *
+ * Evaluates to %TRUE if no triangles uses @s as an edge, %FALSE otherwise.
+ */
+#define       gts_edge_is_unattached(s) ((s)->triangles == NULL ? TRUE : FALSE)
+GtsFace *     gts_edge_has_parent_surface         (GtsEdge * e, 
+						   GtsSurface * surface);
+GtsFace *     gts_edge_has_any_parent_surface     (GtsEdge * e);
+GtsFace *     gts_edge_is_boundary                (GtsEdge * e, 
+						   GtsSurface * surface);
+void          gts_edge_replace                    (GtsEdge * e,
+						   GtsEdge * with);
+GSList *      gts_edges_from_vertices             (GSList * vertices,
+						   GtsSurface * parent);
+guint         gts_edge_face_number                (GtsEdge * e,
+						   GtsSurface * s);
+gboolean      gts_edge_collapse_is_valid          (GtsEdge * e);
+gboolean      gts_edge_collapse_creates_fold      (GtsEdge * e, 
+						   GtsVertex * v,
+						   gdouble max);
+GtsEdge *     gts_edge_is_duplicate               (GtsEdge * e);
+GList *       gts_edges_merge                     (GList * edges);
+gboolean      gts_edge_belongs_to_tetrahedron     (GtsEdge * e);
+guint         gts_edge_is_contact                 (GtsEdge * e);
+void          gts_edge_swap                       (GtsEdge * e, 
+						   GtsSurface * s);
+gboolean      gts_edge_manifold_faces             (GtsEdge * e, 
+						   GtsSurface * s,
+						   GtsFace ** f1, 
+						   GtsFace ** f2);
+
+/* Triangles: triangle.c */
+
+#define GTS_IS_TRIANGLE(obj) (gts_object_is_from_class (obj,\
+							gts_triangle_class ()))
+#define GTS_TRIANGLE(obj)         GTS_OBJECT_CAST (obj,\
+						   GtsTriangle,\
+						   gts_triangle_class ())
+#define GTS_TRIANGLE_CLASS(klass) GTS_OBJECT_CLASS_CAST (klass,\
+							 GtsTriangleClass,\
+							 gts_triangle_class ())
+
+struct _GtsTriangle {
+  GtsObject object;
+
+  GtsEdge * e1;
+  GtsEdge * e2;
+  GtsEdge * e3;
+};
+
+struct _GtsTriangleClass {
+  GtsObjectClass parent_class;
+};
+
+GtsTriangleClass * gts_triangle_class        (void);
+void        gts_triangle_set                 (GtsTriangle * triangle, 
+					      GtsEdge * e1, 
+					      GtsEdge * e2,
+					      GtsEdge * e3);
+GtsTriangle * gts_triangle_new               (GtsTriangleClass * klass, 
+					      GtsEdge * e1, 
+					      GtsEdge * e2,
+					      GtsEdge * e3);
+#define     gts_triangle_vertex(t) (GTS_SEGMENT (GTS_TRIANGLE (t)->e1)->v1 ==\
+                                    GTS_SEGMENT (GTS_TRIANGLE (t)->e2)->v1 || \
+                                    GTS_SEGMENT (GTS_TRIANGLE (t)->e1)->v2 ==\
+                                    GTS_SEGMENT (GTS_TRIANGLE (t)->e2)->v1 ? \
+                                    GTS_SEGMENT (GTS_TRIANGLE (t)->e2)->v2 :\
+                                    GTS_SEGMENT (GTS_TRIANGLE (t)->e2)->v1)
+GtsVertex *   gts_triangle_vertex_opposite  (GtsTriangle * t, 
+					     GtsEdge * e);
+GtsEdge *     gts_triangle_edge_opposite    (GtsTriangle * t, 
+					     GtsVertex * v);
+gdouble       gts_triangles_angle           (GtsTriangle * t1,
+					     GtsTriangle * t2);
+gboolean      gts_triangles_are_compatible  (GtsTriangle * t1, 
+					     GtsTriangle * t2,
+					     GtsEdge * e);
+gdouble       gts_triangle_area             (GtsTriangle * t);
+gdouble       gts_triangle_perimeter        (GtsTriangle * t);
+gdouble       gts_triangle_quality          (GtsTriangle * t);
+void          gts_triangle_normal           (GtsTriangle * t, 
+					     gdouble * x, 
+					     gdouble * y, 
+					     gdouble * z);
+gdouble       gts_triangle_orientation      (GtsTriangle * t);
+void          gts_triangle_revert           (GtsTriangle * t);
+GSList *      gts_triangles_from_edges      (GSList * edges);
+void          gts_triangle_vertices_edges   (GtsTriangle * t, 
+					     GtsEdge * e,
+					     GtsVertex ** v1, 
+					     GtsVertex ** v2, 
+					     GtsVertex ** v3,
+					     GtsEdge ** e1,
+					     GtsEdge ** e2,
+					     GtsEdge ** e3);
+GtsTriangle * gts_triangle_enclosing        (GtsTriangleClass * klass,
+					     GSList * points, 
+					     gdouble scale);
+guint         gts_triangle_neighbor_number  (GtsTriangle * t);
+GSList *      gts_triangle_neighbors        (GtsTriangle * t);
+GtsEdge *     gts_triangles_common_edge     (GtsTriangle * t1,
+					     GtsTriangle * t2);
+GtsTriangle * gts_triangle_is_duplicate     (GtsTriangle * t);
+GtsTriangle * gts_triangle_use_edges        (GtsEdge * e1,
+					     GtsEdge * e2,
+					     GtsEdge * e3);
+gboolean      gts_triangle_is_ok            (GtsTriangle * t);
+void          gts_triangle_vertices         (GtsTriangle * t,
+					     GtsVertex ** v1,
+					     GtsVertex ** v2,
+					     GtsVertex ** v3);
+GtsPoint *    gts_triangle_circumcircle_center (GtsTriangle * t,
+						GtsPointClass * point_class);
+gboolean      gts_triangles_are_folded      (GSList * triangles,
+					     GtsVertex * A, GtsVertex * B,
+					     gdouble max);
+GtsObject *   gts_triangle_is_stabbed       (GtsTriangle * t,
+					     GtsPoint * p,
+					     gdouble * orientation);
+void          gts_triangle_interpolate_height (GtsTriangle * t, 
+					       GtsPoint * p);
+
+/* Faces: face.c */
+
+#define GTS_IS_FACE(obj) (gts_object_is_from_class (obj,\
+						    gts_face_class ()))
+#define GTS_FACE(obj)          GTS_OBJECT_CAST (obj,\
+						GtsFace,\
+						gts_face_class ())
+#define GTS_FACE_CLASS(klass)  GTS_OBJECT_CLASS_CAST (klass,\
+						      GtsFaceClass,\
+						      gts_face_class ())
+
+struct _GtsFace {
+  GtsTriangle triangle;
+
+  GSList * surfaces;
+};
+
+struct _GtsFaceClass {
+  GtsTriangleClass parent_class;
+};
+
+GTS_C_VAR 
+gboolean      gts_allow_floating_faces;
+
+GtsFaceClass * gts_face_class                       (void);
+GtsFace *     gts_face_new                          (GtsFaceClass * klass,
+						     GtsEdge * e1,
+						     GtsEdge * e2,
+						     GtsEdge * e3);
+gboolean      gts_face_has_parent_surface           (GtsFace * f,
+						     GtsSurface * s);
+GSList *      gts_faces_from_edges                  (GSList * edges, 
+						     GtsSurface * s);
+guint         gts_face_neighbor_number              (GtsFace * f, 
+						     GtsSurface * s);
+GSList *      gts_face_neighbors                    (GtsFace * f, 
+						     GtsSurface * s);
+void          gts_face_foreach_neighbor             (GtsFace * f, 
+						     GtsSurface * s, 
+						     GtsFunc func,
+						     gpointer data);
+gboolean      gts_face_is_compatible                (GtsFace * f, 
+						     GtsSurface * s);
+
+/* Matrices: matrix.c */
+
+#define       gts_vector_cross(C,A,B) ((C)[0] = (A)[1]*(B)[2] - (A)[2]*(B)[1],\
+			               (C)[1] = (A)[2]*(B)[0] - (A)[0]*(B)[2],\
+			               (C)[2] = (A)[0]*(B)[1] - (A)[1]*(B)[0])
+
+#define       gts_vector_init(v, p1, p2)   ((v)[0] = (p2)->x - (p1)->x,\
+					    (v)[1] = (p2)->y - (p1)->y,\
+					    (v)[2] = (p2)->z - (p1)->z)
+#define       gts_vector_scalar(v1, v2)    ((v1)[0]*(v2)[0] +\
+					    (v1)[1]*(v2)[1] +\
+					    (v1)[2]*(v2)[2])
+#define       gts_vector_norm(v)   (sqrt ((v)[0]*(v)[0] +\
+                                          (v)[1]*(v)[1] +\
+                                          (v)[2]*(v)[2]))
+#define       gts_vector_normalize(v) {\
+  gdouble __gts_n = gts_vector_norm (v);\
+  if (__gts_n > 0.) {\
+    (v)[0] /= __gts_n;\
+    (v)[1] /= __gts_n;\
+    (v)[2] /= __gts_n;\
+  }\
+}
+GtsMatrix * gts_matrix_new (gdouble a00, gdouble a01, gdouble a02, gdouble a03,
+			    gdouble a10, gdouble a11, gdouble a12, gdouble a13,
+			    gdouble a20, gdouble a21, gdouble a22, gdouble a23,
+			    gdouble a30, gdouble a31, gdouble a32, gdouble a33);
+void gts_matrix_assign (GtsMatrix * m,
+			gdouble a00, gdouble a01, gdouble a02, gdouble a03,
+			gdouble a10, gdouble a11, gdouble a12, gdouble a13,
+			gdouble a20, gdouble a21, gdouble a22, gdouble a23,
+			gdouble a30, gdouble a31, gdouble a32, gdouble a33);
+GtsMatrix *   gts_matrix_projection                  (GtsTriangle * t);
+GtsMatrix *   gts_matrix_transpose                   (GtsMatrix * m);
+gdouble       gts_matrix_determinant                 (GtsMatrix * m);
+GtsMatrix *   gts_matrix_inverse                     (GtsMatrix * m);
+GtsMatrix *   gts_matrix3_inverse                    (GtsMatrix * m);
+void          gts_matrix_print                       (GtsMatrix * m, 
+						      FILE * fptr);
+guint         gts_matrix_compatible_row              (GtsMatrix * A,
+						      GtsVector b,
+						      guint n,
+						      GtsVector A1,
+						      gdouble b1);
+guint         gts_matrix_quadratic_optimization      (GtsMatrix * A,
+						      GtsVector b,
+						      guint n,
+						      GtsMatrix * H,
+						      GtsVector c);
+GtsMatrix *   gts_matrix_product                     (GtsMatrix * m1, 
+						      GtsMatrix * m2);
+GtsMatrix *   gts_matrix_zero                        (GtsMatrix * m);
+GtsMatrix *   gts_matrix_identity                    (GtsMatrix * m);
+GtsMatrix *   gts_matrix_scale                       (GtsMatrix * m, 
+						      GtsVector s);
+GtsMatrix *   gts_matrix_translate                   (GtsMatrix * m, 
+						      GtsVector t);
+GtsMatrix *   gts_matrix_rotate                      (GtsMatrix * m,
+						      GtsVector r,
+						      gdouble angle);
+void          gts_matrix_destroy                     (GtsMatrix * m);
+void          gts_vector_print                       (GtsVector v,
+						      FILE * fptr);
+void          gts_vector4_print                      (GtsVector4 v, 
+						      FILE * fptr);
+
+/* Kdtrees: kdtree.c */
+
+#define       gts_kdtree_destroy(tree)               g_node_destroy(tree)
+
+GNode *       gts_kdtree_new                         (GPtrArray * points,
+						      int (*compare)
+						      (const void *, 
+						       const void *));
+GSList *      gts_kdtree_range                       (GNode * tree,
+						      GtsBBox * bbox,
+						      int (*compare)
+						      (const void *, 
+						      const void *));
+
+/* Bboxtrees: bbtree.c */
+
+/**
+ * GtsBBTreeTraverseFunc:
+ * @bb1: a #GtsBBox.
+ * @bb2: another #GtsBBox.
+ * @data: user data passed to the function.
+ *
+ * User function called for each pair of overlapping bounding
+ * boxes. See gts_bb_tree_traverse_overlapping().
+ */
+typedef void   (*GtsBBTreeTraverseFunc)          (GtsBBox * bb1,
+						  GtsBBox * bb2,
+						  gpointer data);
+/**
+ * GtsBBoxDistFunc:
+ * @p: a #GtsPoint.
+ * @bounded: an object bounded by a #GtsBBox.
+ *
+ * User function returning the (minimum) distance between the object
+ * defined by @bounded and point @p.
+ *
+ * Returns: the distance between @p and @bounded.
+ */
+typedef gdouble (*GtsBBoxDistFunc)               (GtsPoint * p,
+						  gpointer bounded);
+/**
+ * GtsBBoxClosestFunc:
+ * @p: a #GtsPoint.
+ * @bounded: an object bounded by a #GtsBBox.
+ * 
+ * User function returning a #GtsPoint belonging to the object defined
+ * by @bounded and closest to @p.
+ *
+ * Returns: a #GtsPoint.
+ */
+typedef GtsPoint * (*GtsBBoxClosestFunc)         (GtsPoint * p,
+						  gpointer bounded);
+
+/**
+ * GTS_IS_BBOX:
+ * @obj: a #GtsObject.
+ *
+ * Evaluates to %TRUE if @obj is a #GtsBBox, %FALSE otherwise.
+ */
+#define GTS_IS_BBOX(obj)  (gts_object_is_from_class (obj,\
+						     gts_bbox_class ()))
+/**
+ * GTS_BBOX:
+ * @obj: a #GtsObject.
+ *
+ * Casts @obj to #GtsBBox.
+ */
+#define GTS_BBOX(obj)         GTS_OBJECT_CAST (obj,\
+					       GtsBBox,\
+					       gts_bbox_class ())
+/**
+ * GTS_BBOX_CLASS:
+ * @klass: a descendant of #GtsBBoxClass.
+ *
+ * Casts @klass to #GtsBBoxClass.
+ */
+#define GTS_BBOX_CLASS(klass) GTS_OBJECT_CLASS_CAST (klass,\
+						     GtsBBoxClass,\
+						     gts_bbox_class ())
+
+struct _GtsBBox {
+  GtsObject object;
+  gpointer bounded;
+  gdouble x1, y1, z1;
+  gdouble x2, y2, z2;
+};
+
+struct _GtsBBoxClass {
+  GtsObjectClass parent_class;
+};
+
+GtsBBoxClass * gts_bbox_class                (void);
+GtsBBox *  gts_bbox_new                      (GtsBBoxClass * klass,
+					      gpointer bounded,
+					      gdouble x1, 
+					      gdouble y1, 
+					      gdouble z1,
+					      gdouble x2, 
+					      gdouble y2, 
+					      gdouble z2);
+void       gts_bbox_set                      (GtsBBox * bbox,
+					      gpointer bounded,
+					      gdouble x1, 
+					      gdouble y1, 
+					      gdouble z1,
+					      gdouble x2, 
+					      gdouble y2, 
+					      gdouble z2);
+GtsBBox *  gts_bbox_segment                  (GtsBBoxClass * klass,
+					      GtsSegment * s);
+GtsBBox *  gts_bbox_triangle                 (GtsBBoxClass * klass,
+					      GtsTriangle * t);
+GtsBBox *  gts_bbox_surface                  (GtsBBoxClass * klass, 
+					      GtsSurface * surface);
+GtsBBox *  gts_bbox_bboxes                   (GtsBBoxClass * klass,
+					      GSList * bboxes);
+GtsBBox *  gts_bbox_points                   (GtsBBoxClass * klass,
+					      GSList * points);
+/**
+ * gts_bbox_point_is_inside:
+ * @bbox: a #GtsBBox.
+ * @p: a #GtsPoint.
+ *
+ * Evaluates to %TRUE if @p is inside (or on the boundary) of @bbox, %FALSE otherwise.
+ */
+#define    gts_bbox_point_is_inside(bbox, p) ((p)->x >= (bbox)->x1 &&\
+					     (p)->y >= (bbox)->y1 &&\
+                                             (p)->z >= (bbox)->z1 &&\
+                                             (p)->x <= (bbox)->x2 &&\
+					     (p)->y <= (bbox)->y2 &&\
+                                             (p)->z <= (bbox)->z2)
+gboolean   gts_bboxes_are_overlapping        (GtsBBox * bb1, 
+					      GtsBBox * bb2);
+void       gts_bbox_draw                     (GtsBBox * bb, 
+					      FILE * fptr);
+gdouble    gts_bbox_diagonal2                (GtsBBox * bb);
+void       gts_bbox_point_distance2          (GtsBBox * bb, 
+					      GtsPoint * p,
+					      gdouble * min,
+					      gdouble * max);
+gboolean   gts_bbox_is_stabbed               (GtsBBox * bb, 
+					      GtsPoint * p);
+gboolean   gts_bbox_overlaps_triangle        (GtsBBox * bb,
+					      GtsTriangle * t);
+gboolean   gts_bbox_overlaps_segment         (GtsBBox * bb, 
+					      GtsSegment * s);
+
+GNode *    gts_bb_tree_new                   (GSList * bboxes);
+GNode *    gts_bb_tree_surface               (GtsSurface * s);
+GSList *   gts_bb_tree_stabbed               (GNode * tree, 
+					      GtsPoint * p);
+GSList *   gts_bb_tree_overlap               (GNode * tree, 
+					      GtsBBox * bbox);
+gboolean   gts_bb_tree_is_overlapping        (GNode * tree, 
+					      GtsBBox * bbox);
+void       gts_bb_tree_traverse_overlapping  (GNode * tree1, 
+					      GNode * tree2,
+					      GtsBBTreeTraverseFunc func,
+					      gpointer data);
+void       gts_bb_tree_draw                  (GNode * tree, 
+					      guint depth, 
+					      FILE * fptr);
+GSList *   gts_bb_tree_point_closest_bboxes  (GNode * tree, 
+					      GtsPoint * p);
+gdouble    gts_bb_tree_point_distance        (GNode * tree, 
+					      GtsPoint * p,
+					      GtsBBoxDistFunc distance,
+					      GtsBBox ** bbox);
+GtsPoint * gts_bb_tree_point_closest         (GNode * tree, 
+					      GtsPoint * p,
+					      GtsBBoxClosestFunc closest,
+					      gdouble * distance);
+void       gts_bb_tree_segment_distance      (GNode * tree, 
+					      GtsSegment * s,
+					      GtsBBoxDistFunc distance,
+					      gdouble delta,
+					      GtsRange * range);
+void       gts_bb_tree_triangle_distance     (GNode * tree, 
+					      GtsTriangle * t,
+					      GtsBBoxDistFunc distance,
+					      gdouble delta,
+					      GtsRange * range);
+void       gts_bb_tree_surface_distance      (GNode * tree,
+					      GtsSurface * s,
+					      GtsBBoxDistFunc distance,
+					      gdouble delta,
+					      GtsRange * range);
+void       gts_bb_tree_surface_boundary_distance 
+                                             (GNode * tree,
+					      GtsSurface * s,
+					      GtsBBoxDistFunc distance,
+					      gdouble delta,
+					      GtsRange * range);
+void       gts_bb_tree_destroy               (GNode * tree, 
+					      gboolean free_leaves);
+
+/* Surfaces: surface.c */
+
+typedef struct _GtsSurfaceStats        GtsSurfaceStats;
+typedef struct _GtsSurfaceQualityStats GtsSurfaceQualityStats;
+typedef GtsVertex * (*GtsRefineFunc)   (GtsEdge * e,
+					GtsVertexClass * klass,
+					gpointer data);
+typedef GtsVertex * (*GtsCoarsenFunc)  (GtsEdge * e,
+					GtsVertexClass * klass,
+					gpointer data);
+typedef gboolean    (*GtsStopFunc)     (gdouble cost,
+					guint nedge,
+					gpointer data);
+
+struct _GtsSurfaceStats {
+  guint n_faces;
+  guint n_incompatible_faces;
+  guint n_duplicate_faces;
+  guint n_duplicate_edges;
+  guint n_boundary_edges;
+  guint n_non_manifold_edges;
+  GtsRange edges_per_vertex, faces_per_edge;
+  GtsSurface * parent;
+};
+
+struct _GtsSurfaceQualityStats {
+  GtsRange face_quality;
+  GtsRange face_area;
+  GtsRange edge_length;
+  GtsRange edge_angle;
+  GtsSurface * parent;
+};
+
+struct _GtsSurface {
+  GtsObject object;
+
+#ifdef USE_SURFACE_BTREE
+  GTree * faces;
+#else /* not USE_SURFACE_BTREE */
+  GHashTable * faces;
+#endif /* not USE_SURFACE_BTREE */
+  GtsFaceClass * face_class;
+  GtsEdgeClass * edge_class;
+  GtsVertexClass * vertex_class;
+  gboolean keep_faces;
+};
+
+struct _GtsSurfaceClass {
+  GtsObjectClass parent_class;
+
+  void (* add_face)    (GtsSurface *, GtsFace *);
+  void (* remove_face) (GtsSurface *, GtsFace *);
+};
+
+#define GTS_IS_SURFACE(obj) (gts_object_is_from_class (obj,\
+						       gts_surface_class ()))
+#define GTS_SURFACE(obj)         GTS_OBJECT_CAST (obj,\
+						  GtsSurface,\
+						  gts_surface_class ())
+#define GTS_SURFACE_CLASS(klass) GTS_OBJECT_CLASS_CAST (klass,\
+							GtsSurfaceClass,\
+							gts_surface_class ())
+
+GtsSurfaceClass * gts_surface_class        (void);
+GtsSurface * gts_surface_new               (GtsSurfaceClass * klass,
+					    GtsFaceClass * face_class,
+					    GtsEdgeClass * edge_class,
+					    GtsVertexClass * vertex_class);
+void         gts_surface_add_face          (GtsSurface * s, 
+					    GtsFace * f);
+void         gts_surface_remove_face       (GtsSurface * s, 
+					    GtsFace * f);
+guint        gts_surface_read              (GtsSurface * surface,
+					    GtsFile * f);
+gdouble      gts_surface_area              (GtsSurface * s);
+void         gts_surface_stats             (GtsSurface * s, 
+					    GtsSurfaceStats * stats);
+void         gts_surface_quality_stats     (GtsSurface * s, 
+					    GtsSurfaceQualityStats * stats);
+void         gts_surface_print_stats       (GtsSurface * s, 
+					    FILE * fptr);
+void         gts_surface_write             (GtsSurface * s, 
+					    FILE * fptr);
+void         gts_surface_write_oogl        (GtsSurface * s, 
+					    FILE * fptr);
+void         gts_surface_write_vtk         (GtsSurface * s, 
+					    FILE * fptr);
+void         gts_surface_write_oogl_boundary (GtsSurface * s, 
+					      FILE * fptr);
+void         gts_surface_foreach_vertex    (GtsSurface * s, 
+					    GtsFunc func, 
+					    gpointer data);
+void         gts_surface_foreach_edge      (GtsSurface * s, 
+					    GtsFunc func, 
+					    gpointer data);
+void         gts_surface_foreach_face      (GtsSurface * s,
+					    GtsFunc func, 
+					    gpointer data);
+guint        gts_surface_foreach_face_remove (GtsSurface * s,
+					      GtsFunc func, 
+					      gpointer data);
+typedef struct _GtsSurfaceTraverse GtsSurfaceTraverse;
+GtsSurfaceTraverse * gts_surface_traverse_new (GtsSurface * s,
+					       GtsFace * f);
+GtsFace *    gts_surface_traverse_next     (GtsSurfaceTraverse * t,
+					    guint * level);
+void         gts_surface_traverse_destroy  (GtsSurfaceTraverse * t);
+void         gts_surface_refine            (GtsSurface * surface,
+					    GtsKeyFunc cost_func,
+					    gpointer cost_data,
+					    GtsRefineFunc refine_func,
+					    gpointer refine_data,
+					    GtsStopFunc stop_func,
+					    gpointer stop_data);
+gboolean     gts_edge_collapse_is_valid    (GtsEdge * e);
+void         gts_surface_coarsen           (GtsSurface * surface,
+					    GtsKeyFunc cost_func,
+					    gpointer cost_data,
+					    GtsCoarsenFunc coarsen_func,
+					    gpointer coarsen_data,
+					    GtsStopFunc stop_func,
+					    gpointer stop_data,
+					    gdouble minangle);
+gboolean     gts_coarsen_stop_number       (gdouble cost, 
+					    guint nedge, 
+					    guint * min_number);
+gboolean     gts_coarsen_stop_cost         (gdouble cost, 
+					    guint nedge, 
+					    gdouble * max_cost);
+void         gts_surface_tessellate        (GtsSurface * s,
+					    GtsRefineFunc refine_func,
+					    gpointer refine_data);
+GtsSurface * gts_surface_generate_sphere   (GtsSurface * s,
+					    guint geodesation_order);
+GtsSurface * gts_surface_copy              (GtsSurface * s1,
+					    GtsSurface * s2);
+void         gts_surface_merge             (GtsSurface * s, 
+					    GtsSurface * with);
+gboolean     gts_surface_is_manifold       (GtsSurface * s);
+gboolean     gts_surface_is_closed         (GtsSurface * s);
+gboolean     gts_surface_is_orientable     (GtsSurface * s);
+gdouble      gts_surface_volume            (GtsSurface * s);
+gdouble      gts_surface_center_of_mass    (GtsSurface * s,
+					    GtsVector cm);
+gdouble      gts_surface_center_of_area    (GtsSurface * s,
+					    GtsVector cm);
+guint        gts_surface_vertex_number     (GtsSurface * s);
+guint        gts_surface_edge_number       (GtsSurface * s);
+guint        gts_surface_face_number       (GtsSurface * s);
+void         gts_surface_distance          (GtsSurface * s1, 
+					    GtsSurface * s2, 
+					    gdouble delta,
+					    GtsRange * face_range, 
+					    GtsRange * boundary_range);
+GSList *     gts_surface_boundary          (GtsSurface * surface);
+GSList *     gts_surface_split             (GtsSurface * s);
+
+/* Discrete differential operators: curvature.c */
+
+gboolean gts_vertex_mean_curvature_normal  (GtsVertex * v, 
+					    GtsSurface * s, 
+					    GtsVector Kh);
+gboolean gts_vertex_gaussian_curvature     (GtsVertex * v, 
+					    GtsSurface * s, 
+					    gdouble * Kg);
+void     gts_vertex_principal_curvatures   (gdouble Kh, 
+					    gdouble Kg, 
+					    gdouble * K1, 
+					    gdouble * K2);
+void     gts_vertex_principal_directions   (GtsVertex * v, 
+					    GtsSurface * s, 
+					    GtsVector Kh,
+                                            gdouble Kg,
+					    GtsVector e1, 
+					    GtsVector e2);
+
+/* Volume optimization: vopt.c */
+typedef struct _GtsVolumeOptimizedParams   GtsVolumeOptimizedParams;
+
+struct _GtsVolumeOptimizedParams {
+  gdouble volume_weight;
+  gdouble boundary_weight;
+  gdouble shape_weight;
+};
+
+GtsVertex *  gts_volume_optimized_vertex   (GtsEdge * edge,
+					    GtsVertexClass * klass,
+					    GtsVolumeOptimizedParams * params);
+gdouble      gts_volume_optimized_cost     (GtsEdge * e,
+					    GtsVolumeOptimizedParams * params);
+
+/* bool operations: boolean.c */
+
+GSList *     gts_surface_intersection      (GtsSurface * s1,
+					    GtsSurface * s2,
+					    GNode * faces_tree1,
+					    GNode * faces_tree2);
+
+typedef struct _GtsSurfaceInter         GtsSurfaceInter;
+typedef struct _GtsSurfaceInterClass    GtsSurfaceInterClass;
+/**
+ * GtsBooleanOperation:
+ * @GTS_1_OUT_2: identifies the part of the first surface which lies
+ * outside the second surface.
+ * @GTS_1_IN_2: identifies the part of the first surface which lies
+ * inside the second surface.
+ * @GTS_2_OUT_1: identifies the part of the second surface which lies
+ * outside the first surface.
+ * @GTS_2_IN_1: identifies the part of the second surface which lies
+ * inside the first surface.
+ */
+typedef enum { GTS_1_OUT_2, 
+	       GTS_1_IN_2, 
+	       GTS_2_OUT_1, 
+	       GTS_2_IN_1 }             GtsBooleanOperation;
+
+/**
+ * GTS_IS_SURFACE_INTER:
+ * @obj: a #GtsObject.
+ *
+ * Evaluates to %TRUE if @obj is a #GtsSurfaceInter, %FALSE otherwise.
+ */
+#define GTS_IS_SURFACE_INTER(obj) (gts_object_is_from_class (obj,\
+					      gts_surface_inter_class ()))
+/**
+ * GTS_SURFACE_INTER:
+ * @obj: a descendant of #GtsSurfaceInter.
+ *
+ * Casts @obj to #GtsSurfaceInter.
+ */
+#define GTS_SURFACE_INTER(obj)         GTS_OBJECT_CAST (obj,\
+						  GtsSurfaceInter,\
+						  gts_surface_inter_class ())
+/**
+ * GTS_SURFACE_INTER_CLASS:
+ * @klass: a descendant of #GtsSurfaceInterClass.
+ *
+ * Casts @klass to #GtsSurfaceInterClass.
+ */
+#define GTS_SURFACE_INTER_CLASS(klass) GTS_OBJECT_CLASS_CAST (klass,\
+						 GtsSurfaceInterClass,\
+						 gts_surface_inter_class ())
+
+struct _GtsSurfaceInter {
+  GtsObject object;
+
+  GtsSurface * s1;
+  GtsSurface * s2;
+  GSList * edges;
+};
+
+struct _GtsSurfaceInterClass {
+  GtsObjectClass parent_class;
+};
+
+GtsSurfaceInterClass *
+gts_surface_inter_class          (void);
+GtsSurfaceInter *
+gts_surface_inter_new            (GtsSurfaceInterClass * klass,
+				  GtsSurface * s1,
+				  GtsSurface * s2,
+				  GNode * faces_tree1,
+				  GNode * faces_tree2,
+				  gboolean is_open1,
+				  gboolean is_open2);
+gboolean 
+gts_surface_inter_check          (GtsSurfaceInter * si,
+				  gboolean * closed);
+void 
+gts_surface_inter_boolean        (GtsSurfaceInter * si, 
+				  GtsSurface * surface,
+				  GtsBooleanOperation op);
+gboolean gts_surface_foreach_intersecting_face (GtsSurface * s,
+					    GtsBBTreeTraverseFunc func,
+					    gpointer data);
+GtsSurface * 
+gts_surface_is_self_intersecting (GtsSurface * s);
+
+/* Binary Heap: heap.c */
+
+typedef struct _GtsHeap         GtsHeap;
+
+GtsHeap *    gts_heap_new          (GCompareFunc compare_func);
+void         gts_heap_insert       (GtsHeap * heap, gpointer p);
+gpointer     gts_heap_remove_top   (GtsHeap * heap);
+gpointer     gts_heap_top          (GtsHeap * heap);
+void         gts_heap_thaw         (GtsHeap * heap);
+void         gts_heap_foreach      (GtsHeap * heap, 
+				    GFunc func,
+				    gpointer user_data);
+void         gts_heap_freeze       (GtsHeap * heap);
+guint        gts_heap_size         (GtsHeap * heap);
+void         gts_heap_destroy      (GtsHeap * heap);
+
+/* Extended Binary Heap: eheap.c */
+
+typedef struct _GtsEHeap         GtsEHeap;
+typedef struct _GtsEHeapPair     GtsEHeapPair;
+
+struct _GtsEHeap {
+  GPtrArray * elts;
+  GtsKeyFunc func;
+  gpointer data;
+  gboolean frozen, randomized;
+};
+
+/**
+ * _GtsEHeapPair:
+ * @data: Points to the item stored in the heap.
+ * @key: Value of the key for this item.
+ * @pos: Private field.
+ */
+struct _GtsEHeapPair {
+  gpointer data;
+  gdouble key;
+  guint pos;
+};
+
+GtsEHeap *     gts_eheap_new          (GtsKeyFunc key_func,
+				       gpointer data);
+GtsEHeapPair * gts_eheap_insert       (GtsEHeap * heap, 
+				       gpointer p);
+GtsEHeapPair * gts_eheap_insert_with_key (GtsEHeap * heap, 
+					  gpointer p, 
+					  gdouble key);
+gpointer       gts_eheap_remove_top   (GtsEHeap * heap,
+				       gdouble * key);
+gpointer       gts_eheap_top          (GtsEHeap * heap, 
+				       gdouble * key);
+void           gts_eheap_thaw         (GtsEHeap * heap);
+void           gts_eheap_foreach      (GtsEHeap * heap, 
+				       GFunc func,
+				       gpointer data);
+gpointer       gts_eheap_remove       (GtsEHeap * heap, 
+				       GtsEHeapPair * p);
+void           gts_eheap_decrease_key (GtsEHeap * heap,
+				       GtsEHeapPair * p,
+				       gdouble new_key);
+void           gts_eheap_freeze       (GtsEHeap * heap);
+guint          gts_eheap_size         (GtsEHeap * heap);
+void           gts_eheap_update       (GtsEHeap * heap);
+gdouble        gts_eheap_key          (GtsEHeap * heap,
+				       gpointer p);
+void           gts_eheap_randomized   (GtsEHeap * heap, 
+				       gboolean randomized);
+void           gts_eheap_destroy      (GtsEHeap * heap);
+
+/* FIFO queues: fifo.c */
+
+typedef struct _GtsFifo GtsFifo;
+
+GtsFifo *      gts_fifo_new           (void);
+void           gts_fifo_write         (GtsFifo * fifo, 
+				       FILE * fp);
+void           gts_fifo_push          (GtsFifo * fifo, 
+				       gpointer data);
+gpointer       gts_fifo_pop           (GtsFifo * fifo);
+gpointer       gts_fifo_top           (GtsFifo * fifo);
+guint          gts_fifo_size          (GtsFifo * fifo);
+gboolean       gts_fifo_is_empty      (GtsFifo * fifo);
+void           gts_fifo_foreach       (GtsFifo * fifo, 
+				       GtsFunc func, 
+				       gpointer data);
+void           gts_fifo_reverse       (GtsFifo * fifo);
+void           gts_fifo_destroy       (GtsFifo * fifo);
+
+/* Progressive surfaces */
+
+/* split.c */
+
+typedef struct _GtsSplit      GtsSplit;
+typedef struct _GtsSplitClass GtsSplitClass;
+typedef struct _GtsSplitCFace GtsSplitCFace;
+
+struct _GtsSplit {
+  GtsObject object;
+
+  GtsVertex * v;
+  GtsObject * v1;
+  GtsObject * v2;
+  GtsSplitCFace * cfaces;
+  guint ncf;
+};
+
+struct _GtsSplitClass {
+  GtsObjectClass parent_class;
+};
+
+#define GTS_IS_SPLIT(obj)    (gts_object_is_from_class (obj,\
+							gts_split_class ()))
+#define GTS_SPLIT(obj)              GTS_OBJECT_CAST (obj,\
+						     GtsSplit,\
+						     gts_split_class ())
+#define GTS_SPLIT_CLASS(klass)      GTS_OBJECT_CLASS_CAST (klass,\
+						     GtsSplitClass,\
+						     gts_split_class ())
+#define GTS_SPLIT_V1(vs)            (GTS_IS_SPLIT ((vs)->v1) ?\
+				     GTS_SPLIT ((vs)->v1)->v :\
+				     GTS_VERTEX ((vs)->v1))
+#define GTS_SPLIT_V2(vs)            (GTS_IS_SPLIT ((vs)->v2) ?\
+				     GTS_SPLIT ((vs)->v2)->v :\
+				     GTS_VERTEX ((vs)->v2))
+
+GtsSplitClass *  gts_split_class          (void);
+GtsSplit *       gts_split_new            (GtsSplitClass * klass,
+					   GtsVertex * v,
+					   GtsObject * o1,
+					   GtsObject * o2);
+void             gts_split_collapse       (GtsSplit * vs,
+					   GtsEdgeClass * klass,
+					   GtsEHeap * heap);
+void             gts_split_expand         (GtsSplit * vs, 
+					   GtsSurface * s,
+					   GtsEdgeClass * klass);
+typedef gboolean (*GtsSplitTraverseFunc)  (GtsSplit * vs,
+					   gpointer data);
+void             gts_split_traverse       (GtsSplit * root,
+					   GTraverseType        order,
+					   gint                 depth,
+					   GtsSplitTraverseFunc func,
+					   gpointer             data);
+guint            gts_split_height         (GtsSplit * root);
+
+/* psurface.c */
+
+typedef struct _GtsPSurface         GtsPSurface;
+typedef struct _GtsPSurfaceClass    GtsPSurfaceClass;
+
+struct _GtsPSurface {
+  GtsObject object;
+
+  GtsSurface * s;
+  GPtrArray * split;
+  GtsSplitClass * split_class;
+  guint pos, min;
+
+  GPtrArray * vertices;
+  GPtrArray * faces;
+};
+
+struct _GtsPSurfaceClass {
+  GtsObjectClass parent_class;
+};
+
+#define GTS_IS_PSURFACE(obj) (gts_object_is_from_class (obj,\
+							gts_psurface_class ()))
+#define GTS_PSURFACE(obj)           GTS_OBJECT_CAST (obj,\
+						     GtsPSurface,\
+						     gts_psurface_class ())
+#define GTS_PSURFACE_CLASS(klass)     GTS_OBJECT_CLASS_CAST (klass,\
+						     GtsPSurfaceClass,\
+						     gts_psurface_class ())
+#define GTS_PSURFACE_IS_CLOSED(ps)  (!(ps)->vertices)
+
+GtsPSurfaceClass * gts_psurface_class         (void);
+GtsPSurface * gts_psurface_new                (GtsPSurfaceClass * klass,
+					       GtsSurface * surface,
+					       GtsSplitClass * split_class,
+					       GtsKeyFunc cost_func,
+					       gpointer cost_data,
+					       GtsCoarsenFunc coarsen_func,
+					       gpointer coarsen_data,
+					       GtsStopFunc stop_func,
+					       gpointer stop_data,
+					       gdouble minangle);
+GtsSplit *    gts_psurface_add_vertex         (GtsPSurface * ps);
+GtsSplit *    gts_psurface_remove_vertex      (GtsPSurface * ps);
+guint         gts_psurface_max_vertex_number  (GtsPSurface * ps);
+guint         gts_psurface_min_vertex_number  (GtsPSurface * ps);
+void          gts_psurface_set_vertex_number  (GtsPSurface * ps, 
+					       guint n);
+guint         gts_psurface_get_vertex_number  (GtsPSurface * ps);
+void          gts_psurface_write              (GtsPSurface * ps,
+					       FILE * fptr);
+GtsPSurface * gts_psurface_open               (GtsPSurfaceClass * klass,
+					       GtsSurface * s,
+					       GtsSplitClass * split_class,
+					       GtsFile * f);
+GtsSplit *    gts_psurface_read_vertex        (GtsPSurface * ps, 
+					       GtsFile * fp);
+void          gts_psurface_close              (GtsPSurface * ps);
+void          gts_psurface_foreach_vertex     (GtsPSurface * ps, 
+					       GtsFunc func, 
+					       gpointer data);
+
+/* hsurface.c */
+
+typedef struct _GtsHSplit        GtsHSplit;
+typedef struct _GtsHSplitClass   GtsHSplitClass;
+typedef struct _GtsHSurface      GtsHSurface;
+typedef struct _GtsHSurfaceClass GtsHSurfaceClass;
+
+struct _GtsHSplit {
+  GtsSplit split;
+
+  GtsEHeapPair * index;
+  GtsHSplit * parent;
+  guint nchild;
+};
+
+struct _GtsHSplitClass {
+  GtsSplitClass parent_class;
+};
+
+#define GTS_IS_HSPLIT(obj) (gts_object_is_from_class (obj,\
+						      gts_hsplit_class ()))
+#define GTS_HSPLIT(obj)           GTS_OBJECT_CAST (obj,\
+						   GtsHSplit,\
+						   gts_hsplit_class ())
+#define GTS_HSPLIT_CLASS(klass)     GTS_OBJECT_CLASS_CAST (klass,\
+						   GtsHSplitClass,\
+						   gts_hsplit_class ())
+
+GtsHSplitClass * gts_hsplit_class             (void);
+GtsHSplit *   gts_hsplit_new                  (GtsHSplitClass * klass, 
+					       GtsSplit * vs);
+void          gts_hsplit_collapse             (GtsHSplit * hs,
+					       GtsHSurface * hsurface);
+void          gts_hsplit_expand               (GtsHSplit * hs,
+					       GtsHSurface * hsurface);
+void          gts_hsplit_force_expand         (GtsHSplit * hs,
+					       GtsHSurface * hsurface);
+
+struct _GtsHSurface {
+  GtsObject object;
+
+  GtsSurface * s;
+  GSList * roots;
+  GtsEHeap * expandable;
+  GtsEHeap * collapsable;
+  GPtrArray * split;
+  guint nvertex;
+};
+
+struct _GtsHSurfaceClass {
+  GtsObjectClass parent_class;
+};
+
+#define GTS_IS_HSURFACE(obj) (gts_object_is_from_class (obj,\
+							gts_hsurface_class ()))
+#define GTS_HSURFACE(obj)           GTS_OBJECT_CAST (obj,\
+						     GtsHSurface,\
+						     gts_hsurface_class ())
+#define GTS_HSURFACE_CLASS(klass)   GTS_OBJECT_CLASS_CAST (klass,\
+						     GtsHSurfaceClass,\
+						     gts_hsurface_class ())
+
+GtsHSurfaceClass * gts_hsurface_class    (void);
+GtsHSurface * gts_hsurface_new           (GtsHSurfaceClass * klass,
+					  GtsHSplitClass *   hsplit_class,
+					  GtsPSurface *      psurface,
+					  GtsKeyFunc         expand_key,
+					  gpointer           expand_data,
+					  GtsKeyFunc         collapse_key,
+					  gpointer           collapse_data);
+void          gts_hsurface_traverse      (GtsHSurface *        hsurface,
+					  GTraverseType        order,
+					  gint                 depth,
+					  GtsSplitTraverseFunc func,
+					  gpointer             data);
+void          gts_hsurface_foreach       (GtsHSurface *        hsurface,
+					  GTraverseType        order,
+					  GtsFunc              func,
+					  gpointer             data);
+guint         gts_hsurface_height        (GtsHSurface *        hsurface);
+
+/* Constrained Delaunay triangulation: cdt.c */
+
+/**
+ * GTS_IS_CONSTRAINT:
+ * @obj: a #GtsObject.
+ *
+ * Evaluates to %TRUE if @obj is a #GtsConstraint, %FALSE otherwise.
+ */
+#define GTS_IS_CONSTRAINT(obj)      (gts_object_is_from_class (obj,\
+						    gts_constraint_class ()))
+/**
+ * GTS_CONSTRAINT:
+ * @obj: a descendant of #GtsConstraint.
+ *
+ * Casts @obj to #GtsConstraint.
+ */
+#define GTS_CONSTRAINT(obj)          GTS_OBJECT_CAST (obj,\
+						  GtsConstraint,\
+						  gts_constraint_class ())
+/**
+ * GTS_CONSTRAINT_CLASS:
+ * @klass: a desscendant of #GtsConstraintClass.
+ *
+ * Casts @klass to #GtsConstraintClass.
+ */
+#define GTS_CONSTRAINT_CLASS(klass)  GTS_OBJECT_CLASS_CAST (klass,\
+						  GtsConstraintClass,\
+						  gts_constraint_class ())
+
+struct _GtsConstraint {
+  GtsEdge edge;
+};
+
+struct _GtsConstraintClass {
+  GtsEdgeClass parent_class;
+};
+
+typedef struct _GtsConstraint        GtsConstraint;
+typedef struct _GtsConstraintClass   GtsConstraintClass;
+
+GtsConstraintClass * gts_constraint_class        (void);
+
+GtsFace *            gts_point_locate            (GtsPoint * p, 
+						  GtsSurface * surface,
+						  GtsFace * guess);
+GtsVertex *          gts_delaunay_add_vertex_to_face (GtsSurface * surface, 
+						      GtsVertex * v,
+						      GtsFace * f);
+GtsVertex *          gts_delaunay_add_vertex     (GtsSurface * surface, 
+						  GtsVertex * v,
+						  GtsFace * guess);
+void                 gts_delaunay_remove_vertex  (GtsSurface * surface, 
+						  GtsVertex * v);
+GtsFace *            gts_delaunay_check          (GtsSurface * surface);
+GSList *             gts_delaunay_add_constraint (GtsSurface * surface,
+						  GtsConstraint * c);
+void                 gts_delaunay_remove_hull    (GtsSurface * surface);
+
+/* GtsListFace: Header */
+
+typedef struct _GtsListFace         GtsListFace;
+
+struct _GtsListFace {
+  /*< private >*/
+  GtsFace parent;
+
+  /*< public >*/
+  GSList * points;
+};
+
+#define GTS_LIST_FACE(obj)            GTS_OBJECT_CAST (obj,\
+					         GtsListFace,\
+					         gts_list_face_class ())
+#define GTS_IS_LIST_FACE(obj)         (gts_object_is_from_class (obj,\
+						 gts_list_face_class ()))
+
+GtsFaceClass *       gts_list_face_class         (void);
+
+/* Constrained Delaunay refinement: refine.c */
+
+typedef gboolean   (* GtsEncroachFunc)           (GtsVertex * v,
+						  GtsEdge * e,
+						  GtsSurface * s,
+						  gpointer data);
+
+gboolean             gts_vertex_encroaches_edge  (GtsVertex * v, 
+						  GtsEdge * e);
+GtsVertex *          gts_edge_is_encroached      (GtsEdge * e,
+						  GtsSurface * s,
+						  GtsEncroachFunc encroaches,
+						  gpointer data);
+guint                gts_delaunay_conform        (GtsSurface * surface,
+						  gint steiner_max,
+						  GtsEncroachFunc encroaches,
+						  gpointer data);
+guint                gts_delaunay_refine         (GtsSurface * surface,
+						  gint steiner_max,
+						  GtsEncroachFunc encroaches,
+						  gpointer encroach_data,
+						  GtsKeyFunc cost,
+						  gpointer cost_data);
+
+/* Isosurfaces (marching cubes): iso.c */
+
+typedef struct _GtsGridPlane     GtsGridPlane;
+typedef struct _GtsIsoSlice      GtsIsoSlice;
+typedef struct _GtsCartesianGrid GtsCartesianGrid;
+
+struct _GtsGridPlane {
+  GtsPoint ** p;
+  guint nx, ny;
+};
+
+struct _GtsCartesianGrid {
+  guint nx, ny, nz;
+  gdouble x, dx, y, dy, z, dz;
+};
+
+typedef void (*GtsIsoCartesianFunc)         (gdouble ** a,
+					     GtsCartesianGrid g,
+					     guint i,
+					     gpointer data);
+
+GtsGridPlane * gts_grid_plane_new           (guint nx, 
+					     guint ny);
+void           gts_grid_plane_destroy       (GtsGridPlane * g);
+GtsIsoSlice *  gts_iso_slice_new            (guint nx, guint ny);
+void           gts_iso_slice_fill           (GtsIsoSlice * slice,
+					     GtsGridPlane * plane1,
+					     GtsGridPlane * plane2,
+					     gdouble ** f1,
+					     gdouble ** f2,
+					     gdouble iso,
+					     GtsVertexClass * klass);
+void           gts_iso_slice_fill_cartesian (GtsIsoSlice * slice,
+					     GtsCartesianGrid g,
+					     gdouble ** f1,
+					     gdouble ** f2,
+					     gdouble iso,
+					     GtsVertexClass * klass);
+void           gts_iso_slice_destroy        (GtsIsoSlice * slice);
+void           gts_isosurface_slice         (GtsIsoSlice * slice1,
+					     GtsIsoSlice * slice2,
+					     GtsSurface * surface);
+void           gts_isosurface_cartesian     (GtsSurface * surface,
+					     GtsCartesianGrid g,
+					     GtsIsoCartesianFunc f,
+					     gpointer data,
+					     gdouble iso);
+
+/* Isosurfaces (marching tetrahedra): isotetra.c */
+
+void           gts_isosurface_tetra         (GtsSurface * surface,
+					     GtsCartesianGrid g,
+					     GtsIsoCartesianFunc f,
+					     gpointer data,
+					     gdouble iso);
+void           gts_isosurface_tetra_bcl     (GtsSurface * surface,
+					     GtsCartesianGrid g,
+					     GtsIsoCartesianFunc f,
+					     gpointer data,
+					     gdouble iso);
+void           gts_isosurface_tetra_bounded (GtsSurface * surface,
+					     GtsCartesianGrid g,
+					     GtsIsoCartesianFunc f,
+					     gpointer data,
+					     gdouble iso);
+
+/* Named vertices, edges and triangles: named.c */
+
+#define GTS_NAME_LENGTH             40
+
+#define GTS_NVERTEX(obj)            GTS_OBJECT_CAST (obj,\
+						     GtsNVertex,\
+						     gts_nvertex_class ())
+#define GTS_NVERTEX_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+							   GtsNVertexClass,\
+							   gts_nvertex_class())
+#define GTS_IS_NVERTEX(obj)         (gts_object_is_from_class (obj,\
+				       gts_nvertex_class ()))
+
+typedef struct _GtsNVertex          GtsNVertex;
+typedef struct _GtsNVertexClass     GtsNVertexClass;
+
+struct _GtsNVertex {
+  GtsVertex parent;
+  char name[GTS_NAME_LENGTH];
+};
+
+struct _GtsNVertexClass {
+  GtsVertexClass parent_class;
+};
+
+GtsNVertexClass * gts_nvertex_class        (void);
+
+#define GTS_NEDGE(obj)            GTS_OBJECT_CAST (obj,\
+						   GtsNEdge,\
+						   gts_nedge_class ())
+#define GTS_NEDGE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+							 GtsNEdgeClass,\
+							 gts_nedge_class())
+#define GTS_IS_NEDGE(obj)         (gts_object_is_from_class (obj,\
+				       gts_nedge_class ()))
+
+typedef struct _GtsNEdge          GtsNEdge;
+typedef struct _GtsNEdgeClass     GtsNEdgeClass;
+
+struct _GtsNEdge {
+  GtsEdge parent;
+  char name[GTS_NAME_LENGTH];
+};
+
+struct _GtsNEdgeClass {
+  GtsEdgeClass parent_class;
+};
+
+GtsNEdgeClass *   gts_nedge_class        (void);
+
+#define GTS_NFACE(obj)            GTS_OBJECT_CAST (obj,\
+						   GtsNFace,\
+						   gts_nface_class ())
+#define GTS_NFACE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+							 GtsNFaceClass,\
+							 gts_nface_class())
+#define GTS_IS_NFACE(obj)         (gts_object_is_from_class (obj,\
+				       gts_nface_class ()))
+
+typedef struct _GtsNFace          GtsNFace;
+typedef struct _GtsNFaceClass     GtsNFaceClass;
+
+struct _GtsNFace {
+  GtsFace parent;
+  char name[GTS_NAME_LENGTH];
+};
+
+struct _GtsNFaceClass {
+  GtsFaceClass parent_class;
+};
+
+GtsNFaceClass *       gts_nface_class        (void);
+
+/* Cluster object for out-of-core simplification: oocs.c */
+
+#define GTS_CLUSTER(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsCluster,\
+					           gts_cluster_class ())
+#define GTS_CLUSTER_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsClusterClass,\
+						         gts_cluster_class())
+#define GTS_IS_CLUSTER(obj)         (gts_object_is_from_class (obj,\
+						   gts_cluster_class ()))
+     
+typedef struct _GtsCluster         GtsCluster;
+typedef struct _GtsClusterClass    GtsClusterClass;
+typedef struct _GtsClusterId       GtsClusterId;
+
+struct _GtsClusterId {
+  guint x, y, z;
+};
+
+struct _GtsCluster {
+  GtsObject parent;
+
+  GtsClusterId id;
+  GtsVertex * v;
+  guint n;
+};
+
+struct _GtsClusterClass {
+  GtsObjectClass parent_class;
+
+  void (* add) (GtsCluster * c, GtsPoint * p, gpointer data);
+  void (* update) (GtsCluster * c);
+};
+
+GtsClusterClass * gts_cluster_class                (void);
+GtsCluster *      gts_cluster_new                  (GtsClusterClass * klass,
+						    GtsClusterId id,
+						    GtsVertexClass * vklass);
+void              gts_cluster_add                  (GtsCluster * c, 
+						    GtsPoint * p,
+						    gpointer data);
+void              gts_cluster_update               (GtsCluster * c);
+
+/* Cluster group object for out-of-core simplification: oocs.c */
+
+#define GTS_CLUSTER_GRID(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsClusterGrid,\
+					           gts_cluster_grid_class ())
+#define GTS_CLUSTER_GRID_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						   GtsClusterGridClass,\
+						   gts_cluster_grid_class())
+#define GTS_IS_CLUSTER_GRID(obj)         (gts_object_is_from_class (obj,\
+						   gts_cluster_grid_class ()))
+     
+typedef struct _GtsClusterGrid         GtsClusterGrid;
+typedef struct _GtsClusterGridClass    GtsClusterGridClass;
+
+struct _GtsClusterGrid {
+  GtsObject parent;
+
+  GtsSurface * surface;
+  GtsBBox * bbox;
+  GtsVector size;
+
+  GtsClusterClass * cluster_class;
+  GHashTable * clusters;
+};
+
+struct _GtsClusterGridClass {
+  GtsObjectClass parent_class;
+};
+
+GtsClusterGridClass * gts_cluster_grid_class (void);
+GtsClusterGrid *      gts_cluster_grid_new   (GtsClusterGridClass * klass,
+					      GtsClusterClass * cluster_class,
+					      GtsSurface * s,
+					      GtsBBox * bbox,
+					      gdouble delta);
+void           gts_cluster_grid_add_triangle (GtsClusterGrid * cluster_grid,
+					      GtsPoint * p1,
+					      GtsPoint * p2,
+					      GtsPoint * p3,
+					      gpointer data);
+GtsRange       gts_cluster_grid_update       (GtsClusterGrid * cluster_grid);
+
+/* Triangle strip generation: stripe.c */
+GSList *       gts_surface_strip             (GtsSurface * s);
+
+/* GtsContainee: container.c */
+
+typedef struct _GtsContainee         GtsContainee;
+typedef struct _GtsContaineeClass    GtsContaineeClass;
+typedef struct _GtsContainer         GtsContainer;
+typedef struct _GtsContainerClass    GtsContainerClass;
+
+struct _GtsContainee {
+  GtsObject object;
+};
+
+struct _GtsContaineeClass {
+  GtsObjectClass parent_class;
+
+  void     (* add_container)    (GtsContainee *, GtsContainer *);
+  void     (* remove_container) (GtsContainee *, GtsContainer *);
+  void     (* foreach)          (GtsContainee *, GtsFunc, gpointer);
+  gboolean (* is_contained)     (GtsContainee *, GtsContainer *);
+  void     (* replace)          (GtsContainee *, GtsContainee *);
+};
+
+#define GTS_CONTAINEE(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsContainee,\
+					           gts_containee_class ())
+#define GTS_CONTAINEE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsContaineeClass,\
+						         gts_containee_class())
+#define GTS_IS_CONTAINEE(obj)         (gts_object_is_from_class (obj,\
+						   gts_containee_class ()))
+     
+GtsContaineeClass * gts_containee_class        (void);
+GtsContainee *      gts_containee_new          (GtsContaineeClass * klass);
+gboolean            gts_containee_is_contained (GtsContainee * item, 
+						GtsContainer * c);
+void                gts_containee_replace      (GtsContainee * item,
+						GtsContainee * with);
+
+/* GtsSListContainee: container.c */
+
+typedef struct _GtsSListContainee         GtsSListContainee;
+typedef struct _GtsSListContaineeClass    GtsSListContaineeClass;
+
+struct _GtsSListContainee {
+  GtsContainee containee;
+
+  GSList * containers;
+};
+
+struct _GtsSListContaineeClass {
+  GtsContaineeClass parent_class;
+};
+
+#define GTS_SLIST_CONTAINEE(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsSListContainee,\
+					           gts_slist_containee_class ())
+#define GTS_SLIST_CONTAINEE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsSListContaineeClass,\
+						         gts_slist_containee_class())
+#define GTS_IS_SLIST_CONTAINEE(obj)         (gts_object_is_from_class (obj,\
+						   gts_slist_containee_class ()))
+     
+GtsSListContaineeClass * gts_slist_containee_class   (void);
+
+/* GtsContainer: container.c */
+
+struct _GtsContainer {
+  GtsSListContainee object;
+};
+
+struct _GtsContainerClass {
+  GtsSListContaineeClass parent_class;
+
+  void  (* add)     (GtsContainer *, GtsContainee *);
+  void  (* remove)  (GtsContainer *, GtsContainee *);
+  void  (* foreach) (GtsContainer *, GtsFunc, gpointer);
+  guint (* size)    (GtsContainer *);
+};
+
+#define GTS_CONTAINER(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsContainer,\
+					           gts_container_class ())
+#define GTS_CONTAINER_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsContainerClass,\
+						         gts_container_class())
+#define GTS_IS_CONTAINER(obj)         (gts_object_is_from_class (obj,\
+						   gts_container_class ()))
+     
+GtsContainerClass * gts_container_class     (void);
+GtsContainer *      gts_container_new       (GtsContainerClass * klass);
+void                gts_container_add       (GtsContainer * c,
+					     GtsContainee * item);
+void                gts_container_remove    (GtsContainer * c,
+					     GtsContainee * item);
+void                gts_container_foreach   (GtsContainer * c,
+					     GtsFunc func,
+					     gpointer data);
+guint               gts_container_size      (GtsContainer * c);
+
+/* GtsHashContainer: container.c */
+
+typedef struct _GtsHashContainer         GtsHashContainer;
+typedef struct _GtsHashContainerClass    GtsHashContainerClass;
+
+struct _GtsHashContainer {
+  GtsContainer c;
+
+  GHashTable * items;
+  gboolean frozen;
+};
+
+struct _GtsHashContainerClass {
+  GtsContainerClass parent_class;
+};
+
+#define GTS_HASH_CONTAINER(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsHashContainer,\
+					           gts_hash_container_class ())
+#define GTS_HASH_CONTAINER_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsHashContainerClass,\
+						         gts_hash_container_class())
+#define GTS_IS_HASH_CONTAINER(obj)         (gts_object_is_from_class (obj,\
+						   gts_hash_container_class ()))
+     
+GtsHashContainerClass * gts_hash_container_class (void);
+
+/* GtsSListContainer: container.c */
+
+typedef struct _GtsSListContainer         GtsSListContainer;
+typedef struct _GtsSListContainerClass    GtsSListContainerClass;
+
+struct _GtsSListContainer {
+  GtsContainer c;
+
+  GSList * items;
+  gboolean frozen;
+};
+
+struct _GtsSListContainerClass {
+  GtsContainerClass parent_class;
+};
+
+#define GTS_SLIST_CONTAINER(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsSListContainer,\
+					           gts_slist_container_class ())
+#define GTS_SLIST_CONTAINER_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsSListContainerClass,\
+						         gts_slist_container_class())
+#define GTS_IS_SLIST_CONTAINER(obj)         (gts_object_is_from_class (obj,\
+						   gts_slist_container_class ()))
+     
+GtsSListContainerClass * gts_slist_container_class (void);
+
+/* GtsGNode: graph.c */
+
+typedef struct _GtsGNode         GtsGNode;
+typedef struct _GtsGNodeClass    GtsGNodeClass;
+typedef struct _GtsGraph         GtsGraph;
+typedef struct _GtsGraphClass    GtsGraphClass;
+
+struct _GtsGNode {
+  GtsSListContainer container;
+
+  guint level;
+};
+
+struct _GtsGNodeClass {
+  GtsSListContainerClass parent_class;
+
+  gfloat (* weight) (GtsGNode *);
+  void   (* write)  (GtsGNode *, FILE *);
+};
+
+#define GTS_GNODE(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsGNode,\
+					           gts_gnode_class ())
+#define GTS_GNODE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsGNodeClass,\
+						         gts_gnode_class())
+#define GTS_IS_GNODE(obj)         (gts_object_is_from_class (obj,\
+						   gts_gnode_class ()))
+#define GTS_GNODE_NEIGHBOR(n,e)   (GTS_GEDGE (e)->n1 == n ? GTS_GEDGE (e)->n2 : GTS_GEDGE (e)->n2 == n ? GTS_GEDGE (e)->n1 : NULL)
+     
+GtsGNodeClass * gts_gnode_class                (void);
+GtsGNode *      gts_gnode_new                  (GtsGNodeClass * klass);
+void            gts_gnode_foreach_neighbor     (GtsGNode * n, 
+						GtsGraph * g,
+						GtsFunc func,
+						gpointer data);
+void            gts_gnode_foreach_edge         (GtsGNode * n,
+						GtsGraph * g,
+						GtsFunc func,
+						gpointer data);
+guint           gts_gnode_degree               (GtsGNode * n,
+						GtsGraph * g);
+gfloat          gts_gnode_move_cost            (GtsGNode * n,
+						GtsGraph * src,
+						GtsGraph * dst);
+gfloat          gts_gnode_weight               (GtsGNode * n);
+
+GTS_C_VAR
+gboolean        gts_allow_floating_gnodes;
+
+/* GtsNGNode: graph.c */
+
+typedef struct _GtsNGNode         GtsNGNode;
+typedef struct _GtsNGNodeClass    GtsNGNodeClass;
+
+struct _GtsNGNode {
+  GtsGNode node;
+
+  guint id;
+};
+
+struct _GtsNGNodeClass {
+  GtsGNodeClass parent_class;
+};
+
+#define GTS_NGNODE(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsNGNode,\
+					           gts_ngnode_class ())
+#define GTS_NGNODE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsNGNodeClass,\
+						         gts_ngnode_class())
+#define GTS_IS_NGNODE(obj)         (gts_object_is_from_class (obj,\
+						   gts_ngnode_class ()))
+     
+GtsNGNodeClass * gts_ngnode_class                (void);
+GtsNGNode *      gts_ngnode_new                  (GtsNGNodeClass * klass,
+						  guint id);
+
+/* GtsWGNode: graph.c */
+
+typedef struct _GtsWGNode         GtsWGNode;
+typedef struct _GtsWGNodeClass    GtsWGNodeClass;
+
+struct _GtsWGNode {
+  GtsGNode node;
+  
+  gfloat weight;
+};
+
+struct _GtsWGNodeClass {
+  GtsGNodeClass parent_class;
+};
+
+#define GTS_WGNODE(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsWGNode,\
+					           gts_wgnode_class ())
+#define GTS_WGNODE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsWGNodeClass,\
+						         gts_wgnode_class())
+#define GTS_IS_WGNODE(obj)         (gts_object_is_from_class (obj,\
+						   gts_wgnode_class ()))
+     
+GtsWGNodeClass * gts_wgnode_class                (void);
+GtsWGNode *      gts_wgnode_new                  (GtsWGNodeClass * klass,
+						  gfloat weight);
+
+/* GtsPNode */
+
+typedef struct _GtsPNode         GtsPNode;
+typedef struct _GtsPNodeClass    GtsPNodeClass;
+
+struct _GtsPNode {
+  GtsGNode node;
+
+  gpointer data;
+};
+
+struct _GtsPNodeClass {
+  GtsGNodeClass parent_class;
+};
+
+#define GTS_PNODE(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsPNode,\
+					           gts_pnode_class ())
+#define GTS_PNODE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsPNodeClass,\
+						         gts_pnode_class())
+#define GTS_IS_PNODE(obj)         (gts_object_is_from_class (obj,\
+						   gts_pnode_class ()))
+     
+GtsPNodeClass * gts_pnode_class                (void);
+GtsPNode *      gts_pnode_new                  (GtsPNodeClass * klass,
+						gpointer data);
+
+/* GtsFNode */
+
+typedef struct _GtsFNode         GtsFNode;
+typedef struct _GtsFNodeClass    GtsFNodeClass;
+
+struct _GtsFNode {
+  GtsGNode node;
+
+  GtsFace * f;
+};
+
+struct _GtsFNodeClass {
+  GtsGNodeClass parent_class;
+};
+
+#define GTS_FNODE(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsFNode,\
+					           gts_fnode_class ())
+#define GTS_FNODE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsFNodeClass,\
+						         gts_fnode_class())
+#define GTS_IS_FNODE(obj)         (gts_object_is_from_class (obj,\
+						   gts_fnode_class ()))
+     
+GtsFNodeClass * gts_fnode_class                (void);
+GtsFNode *      gts_fnode_new                  (GtsFNodeClass * klass,
+						GtsFace * f);
+
+/* GtsGEdge: graph.c */
+
+typedef struct _GtsGEdge         GtsGEdge;
+typedef struct _GtsGEdgeClass    GtsGEdgeClass;
+
+struct _GtsGEdge {
+  GtsContainee containee;
+
+  GtsGNode * n1;
+  GtsGNode * n2;
+};
+
+struct _GtsGEdgeClass {
+  GtsContaineeClass parent_class;
+
+  GtsGEdge * (* link)   (GtsGEdge * e, GtsGNode * n1, GtsGNode * n2);
+  gfloat     (* weight) (GtsGEdge * e);
+  void       (* write)  (GtsGEdge * e, FILE * fp);
+};
+
+#define GTS_GEDGE(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsGEdge,\
+					           gts_gedge_class ())
+#define GTS_GEDGE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsGEdgeClass,\
+						         gts_gedge_class())
+#define GTS_IS_GEDGE(obj)         (gts_object_is_from_class (obj,\
+						   gts_gedge_class ()))
+     
+GtsGEdgeClass * gts_gedge_class                (void);
+GtsGEdge *      gts_gedge_new                  (GtsGEdgeClass * klass,
+						GtsGNode * n1,
+						GtsGNode * n2);
+gfloat          gts_gedge_weight               (GtsGEdge * e);
+#define         gts_gedge_connects(e, a1, a2)\
+   (((e)->n1 == a1 && (e)->n2 == a2) || ((e)->n1 == a2 && (e)->n2 == a1)) 
+
+/* GtsPGEdge: graph.c */
+
+typedef struct _GtsPGEdge         GtsPGEdge;
+typedef struct _GtsPGEdgeClass    GtsPGEdgeClass;
+
+struct _GtsPGEdge {
+  GtsGEdge gedge;
+
+  gpointer data;
+};
+
+struct _GtsPGEdgeClass {
+  GtsGEdgeClass parent_class;
+};
+
+#define GTS_PGEDGE(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsPGEdge,\
+					           gts_pgedge_class ())
+#define GTS_PGEDGE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsPGEdgeClass,\
+						         gts_pgedge_class())
+#define GTS_IS_PGEDGE(obj)         (gts_object_is_from_class (obj,\
+						   gts_pgedge_class ()))
+     
+GtsPGEdgeClass * gts_pgedge_class                (void);
+GtsPGEdge *      gts_pgedge_new                  (GtsPGEdgeClass * klass,
+						  GtsGNode * n1,
+						  GtsGNode * n2,
+						  gpointer data);
+
+/* GtsWGEdge: graph.c */
+
+typedef struct _GtsWGEdge         GtsWGEdge;
+typedef struct _GtsWGEdgeClass    GtsWGEdgeClass;
+
+struct _GtsWGEdge {
+  GtsGEdge gedge;
+
+  gfloat weight;
+};
+
+struct _GtsWGEdgeClass {
+  GtsGEdgeClass parent_class;
+};
+
+#define GTS_WGEDGE(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsWGEdge,\
+					           gts_wgedge_class ())
+#define GTS_WGEDGE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsWGEdgeClass,\
+						         gts_wgedge_class())
+#define GTS_IS_WGEDGE(obj)         (gts_object_is_from_class (obj,\
+						   gts_wgedge_class ()))
+     
+GtsWGEdgeClass * gts_wgedge_class                (void);
+GtsWGEdge *      gts_wgedge_new                  (GtsWGEdgeClass * klass,
+						  GtsGNode * n1,
+						  GtsGNode * n2,
+						  gfloat weight);
+
+/* GtsGraph: graph.c */
+
+struct _GtsGraph {
+  GtsHashContainer object;
+
+  GtsGraphClass * graph_class;
+  GtsGNodeClass * node_class;
+  GtsGEdgeClass * edge_class;
+};
+
+struct _GtsGraphClass {
+  GtsHashContainerClass parent_class;
+
+  gfloat (* weight) (GtsGraph *);
+};
+
+#define GTS_GRAPH(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsGraph,\
+					           gts_graph_class ())
+#define GTS_GRAPH_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsGraphClass,\
+						         gts_graph_class())
+#define GTS_IS_GRAPH(obj)         (gts_object_is_from_class (obj,\
+						   gts_graph_class ()))
+     
+GtsGraphClass * gts_graph_class                  (void);
+GtsGraph *      gts_graph_new                    (GtsGraphClass * klass,
+						  GtsGNodeClass * node_class,
+						  GtsGEdgeClass * edge_class);
+void            gts_graph_print_stats            (GtsGraph * g,
+						  FILE * fp);
+typedef struct _GtsGraphTraverse GtsGraphTraverse;
+typedef enum   { GTS_BREADTH_FIRST
+               }   GtsTraverseType;
+GtsGraphTraverse * gts_graph_traverse_new        (GtsGraph * g, 
+						  GtsGNode * n,
+						  GtsTraverseType type,
+						  gboolean reinit);
+GtsGNode *         gts_graph_traverse_next       (GtsGraphTraverse * t);
+GtsGNode *         gts_graph_traverse_what_next  (GtsGraphTraverse * t);
+void               gts_graph_traverse_destroy    (GtsGraphTraverse * t);
+void               gts_graph_foreach_edge        (GtsGraph * g,
+						  GtsFunc func,
+						  gpointer data);
+gfloat             gts_graph_weight              (GtsGraph * g);
+guint              gts_graph_distance_sum        (GtsGraph * g, 
+						  GtsGNode * center);
+GtsGNode *         gts_graph_farthest            (GtsGraph * g, 
+						  GSList * gnodes);
+guint              gts_graph_edges_cut           (GtsGraph * g);
+gfloat             gts_graph_edges_cut_weight    (GtsGraph * g);
+void               gts_graph_write               (GtsGraph * g, 
+						  FILE * fp);
+void               gts_graph_write_dot           (GtsGraph * g, 
+						  FILE * fp);
+GtsGraph *         gts_graph_read                (GtsFile * fp);
+guint              gts_graph_read_jostle         (GtsGraph * g, 
+						  GtsFile * fp);
+
+/* GtsWGraph: graph.c */
+
+typedef struct _GtsWGraph      GtsWGraph;
+typedef struct _GtsWGraphClass GtsWGraphClass;
+
+struct _GtsWGraph {
+  GtsGraph graph;
+
+  gfloat weight;
+};
+
+struct _GtsWGraphClass {
+  GtsGraphClass parent_class;
+};
+
+#define GTS_WGRAPH(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsWGraph,\
+					           gts_wgraph_class ())
+#define GTS_WGRAPH_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsWGraphClass,\
+						         gts_wgraph_class())
+#define GTS_IS_WGRAPH(obj)         (gts_object_is_from_class (obj,\
+						   gts_wgraph_class ()))
+     
+GtsWGraphClass * gts_wgraph_class                (void);
+gfloat           gts_wgraph_weight_max           (GtsWGraph * wg);
+
+/* Surface graph: graph.c */
+
+GtsGraph *       gts_surface_graph_new           (GtsGraphClass * klass,
+						  GtsSurface * s);
+GtsSurface *     gts_surface_graph_surface       (GtsGraph * surface_graph,
+						  GtsSurface * s);
+
+/* Segments graph: graph.c */
+
+GtsGraph *       gts_segments_graph_new          (GtsGraphClass * klass,
+						  GSList * segments);
+
+/* GtsGNodeSplit: pgraph.c */
+
+typedef struct _GtsGNodeSplit         GtsGNodeSplit;
+typedef struct _GtsGNodeSplitClass    GtsGNodeSplitClass;
+
+struct _GtsGNodeSplit {
+  GtsObject object;
+
+  GtsGNode * n;
+  GtsObject * n1;
+  GtsObject * n2;
+};
+
+struct _GtsGNodeSplitClass {
+  GtsObjectClass parent_class;
+};
+
+#define GTS_GNODE_SPLIT(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsGNodeSplit,\
+					           gts_gnode_split_class ())
+#define GTS_GNODE_SPLIT_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsGNodeSplitClass,\
+						         gts_gnode_split_class())
+#define GTS_IS_GNODE_SPLIT(obj)         (gts_object_is_from_class (obj,\
+						   gts_gnode_split_class ()))
+#define GTS_GNODE_SPLIT_N1(ns) (GTS_IS_GNODE_SPLIT ((ns)->n1) ? GTS_GNODE_SPLIT ((ns)->n1)->n : GTS_GNODE ((ns)->n1))
+#define GTS_GNODE_SPLIT_N2(ns) (GTS_IS_GNODE_SPLIT ((ns)->n2) ? GTS_GNODE_SPLIT ((ns)->n2)->n : GTS_GNODE ((ns)->n2))
+     
+GtsGNodeSplitClass * gts_gnode_split_class    (void);
+GtsGNodeSplit *      gts_gnode_split_new      (GtsGNodeSplitClass * klass,
+					       GtsGNode * n,
+					       GtsObject * n1,
+					       GtsObject * n2);
+void                 gts_gnode_split_collapse (GtsGNodeSplit * ns,
+					       GtsGraph * g,
+					       GtsWGEdgeClass * klass);
+void                 gts_gnode_split_expand   (GtsGNodeSplit * ns,
+					       GtsGraph * g);
+
+/* GtsPGraph: pgraph.c */
+
+typedef struct _GtsPGraph         GtsPGraph;
+typedef struct _GtsPGraphClass    GtsPGraphClass;
+
+struct _GtsPGraph {
+  GtsObject object;
+
+  GtsGraph * g;
+  GPtrArray * split;
+  GArray * levels;
+  GtsGNodeSplitClass * split_class;
+  GtsWGEdgeClass * edge_class;
+  guint pos, min, level;
+};
+
+struct _GtsPGraphClass {
+  GtsObjectClass parent_class;
+};
+
+#define GTS_PGRAPH(obj)            GTS_OBJECT_CAST (obj,\
+					           GtsPGraph,\
+					           gts_pgraph_class ())
+#define GTS_PGRAPH_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
+						         GtsPGraphClass,\
+						         gts_pgraph_class())
+#define GTS_IS_PGRAPH(obj)         (gts_object_is_from_class (obj,\
+						   gts_pgraph_class ()))
+     
+GtsPGraphClass * gts_pgraph_class            (void);
+GtsPGraph *      gts_pgraph_new              (GtsPGraphClass * klass,
+					      GtsGraph * g,
+					      GtsGNodeSplitClass * split_class,
+					      GtsWGNodeClass * node_class,
+					      GtsWGEdgeClass * edge_class,
+					      guint min);
+GtsGNodeSplit *  gts_pgraph_add_node         (GtsPGraph * pg);
+GtsGNodeSplit *  gts_pgraph_remove_node      (GtsPGraph * pg);
+void             gts_pgraph_set_node_number  (GtsPGraph *pg,
+					      guint n);
+guint            gts_pgraph_get_node_number  (GtsPGraph *pg);
+guint            gts_pgraph_min_node_number  (GtsPGraph *pg);
+guint            gts_pgraph_max_node_number  (GtsPGraph *pg);
+void             gts_pgraph_foreach_node     (GtsPGraph *pg,
+					      GtsFunc func,
+					      gpointer data);
+gboolean         gts_pgraph_down             (GtsPGraph * pg,
+					      GtsFunc func,
+					      gpointer data);
+/* Graph partition: partition.c */
+
+GSList *         gts_graph_bubble_partition           (GtsGraph * g, 
+						       guint np, 
+						       guint niter,
+						       GtsFunc step_info,
+						       gpointer data);
+guint            gts_graph_partition_edges_cut        (GSList * partition);
+gfloat           gts_graph_partition_edges_cut_weight (GSList * partition);
+void             gts_graph_partition_print_stats      (GSList * partition,
+						       FILE * fp);
+gfloat           gts_graph_partition_balance          (GSList * partition);
+GSList *         gts_graph_partition_clone            (GSList * partition);
+GSList *         gts_graph_recursive_bisection        (GtsWGraph * wg,
+						       guint n,
+						       guint ntry,
+						       guint mmax,
+						       guint nmin,
+						       gfloat imbalance);
+void             gts_graph_partition_destroy          (GSList * partition);
+
+/* Graph bisection: partition.c */
+
+typedef struct _GtsGraphBisection GtsGraphBisection;
+
+struct _GtsGraphBisection {
+  GtsGraph * g;
+  GtsGraph * g1;
+  GtsGraph * g2;
+  GHashTable * bg1;
+  GHashTable * bg2;
+};
+
+gboolean            gts_graph_bisection_check      (GtsGraphBisection * bg);
+GtsGraphBisection * gts_graph_ggg_bisection        (GtsGraph * g, 
+						    guint ntry);
+GtsGraphBisection * gts_graph_bfgg_bisection       (GtsGraph * g, 
+						    guint ntry);
+gdouble             gts_graph_bisection_kl_refine  (GtsGraphBisection * bg,
+						    guint mmax);
+gdouble             gts_graph_bisection_bkl_refine (GtsGraphBisection * bg,
+						    guint mmax,
+						    gfloat imbalance);
+GtsGraphBisection * gts_graph_bisection_new        (GtsWGraph * wg,
+						    guint ntry,
+						    guint mmax,
+						    guint nmin,
+						    gfloat imbalance);
+void                gts_graph_bisection_destroy    (GtsGraphBisection * bg,
+						    gboolean destroy_graphs);
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
+#endif /* __GTS_H__ */
diff --git a/gts/heap.c b/gts/heap.c
new file mode 100644
index 0000000..4a37e58
--- /dev/null
+++ b/gts/heap.c
@@ -0,0 +1,258 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <stdlib.h>
+#include "gts.h"
+
+#define PARENT(i) ((i) >= 2 ? (i)/2 : 0)
+#define LEFT_CHILD(i) (2*(i))
+#define RIGHT_CHILD(i) (2*(i) + 1)
+
+struct _GtsHeap {
+  GPtrArray * elts;
+  GCompareFunc func;
+  gboolean frozen;
+};
+
+/**
+ * gts_heap_new:
+ * @compare_func: a GCompareFunc.
+ *
+ * Returns: a new #GtsHeap using @compare_func as a sorting function.
+ */
+GtsHeap * gts_heap_new (GCompareFunc compare_func)
+{
+  GtsHeap * heap;
+
+  g_return_val_if_fail (compare_func != NULL, NULL);
+  
+  heap = g_malloc (sizeof(GtsHeap));
+  heap->elts = g_ptr_array_new ();
+  heap->func = compare_func;
+  heap->frozen = FALSE;
+  return heap;
+}
+
+static void sift_up (GtsHeap * heap, guint i)
+{
+  gpointer parent, child;
+  guint p;
+  gpointer * pdata = heap->elts->pdata;
+  GCompareFunc func = heap->func;
+
+  child = pdata[i - 1];
+  while ((p = PARENT (i))) {
+    parent = pdata[p - 1];
+    if ((*func) (parent, child) > 0) {
+      pdata[p - 1] = child;
+      pdata[i - 1] = parent;
+      i = p;
+    }
+    else
+      i = 0;
+  }
+}
+
+/**
+ * gts_heap_insert:
+ * @heap: a #GtsHeap.
+ * @p: a pointer to add to the heap.
+ *
+ * Inserts a new element @p in the heap.
+ */
+void gts_heap_insert (GtsHeap * heap, gpointer p)
+{
+  g_return_if_fail (heap != NULL);
+
+  g_ptr_array_add (heap->elts, p);
+  if (!heap->frozen)
+    sift_up (heap, heap->elts->len);
+}
+
+static void sift_down (GtsHeap * heap, guint i)
+{
+  gpointer left_child, right_child, child, parent;
+  guint lc, rc, c;
+  gpointer * pdata = heap->elts->pdata;
+  guint len = heap->elts->len;
+  GCompareFunc func = heap->func;
+
+  lc = LEFT_CHILD (i);
+  rc = RIGHT_CHILD (i);
+  left_child = lc <= len ? pdata[lc - 1] : NULL;
+  right_child = rc <= len ? pdata[rc - 1] : NULL;
+
+  parent = pdata[i - 1];
+  while (left_child != NULL) {
+    if (right_child == NULL ||
+	(*func) (left_child, right_child) < 0) {
+      child = left_child;
+      c = lc;
+    }
+    else {
+      child = right_child;
+      c = rc;
+    }
+    if ((*func) (parent, child) > 0) {
+      pdata[i - 1] = child;
+      pdata[c - 1] = parent;
+      i = c;
+      lc = LEFT_CHILD (i);
+      rc = RIGHT_CHILD (i);
+      left_child = lc <= len ? pdata[lc - 1] : NULL;
+      right_child = rc <= len ? pdata[rc - 1] : NULL;      
+    }
+    else
+      left_child = NULL;
+  }
+}
+
+/**
+ * gts_heap_remove_top:
+ * @heap: a #GtsHeap.
+ *
+ * Removes the element at the top of the heap.
+ *
+ * Returns: the element at the top of the heap.
+ */
+gpointer gts_heap_remove_top (GtsHeap * heap)
+{
+  gpointer root;
+  GPtrArray * elts;
+  guint len;
+
+  g_return_val_if_fail (heap != NULL, NULL);
+
+  elts = heap->elts; len = elts->len;
+
+  if (len == 0)
+    return NULL;
+  if (len == 1)
+    return g_ptr_array_remove_index (elts, 0);
+
+  root = elts->pdata[0];
+  elts->pdata[0] = g_ptr_array_remove_index (elts, len - 1);
+  sift_down (heap, 1);
+  return root;
+}
+
+/**
+ * gts_heap_top:
+ * @heap: a #GtsHeap.
+ *
+ * Returns: the element at the top of the heap.
+ */
+gpointer gts_heap_top (GtsHeap * heap)
+{
+  GPtrArray * elts;
+  guint len;
+
+  g_return_val_if_fail (heap != NULL, NULL);
+
+  elts = heap->elts; 
+  len = elts->len;
+  if (len == 0)
+    return NULL;
+  return elts->pdata[0];
+}
+
+/**
+ * gts_heap_destroy:
+ * @heap: a #GtsHeap.
+ * 
+ * Free all the memory allocated for @heap.
+ */
+void gts_heap_destroy (GtsHeap * heap)
+{
+  g_return_if_fail (heap != NULL);
+
+  g_ptr_array_free (heap->elts, TRUE);
+  g_free (heap);
+}
+
+/**
+ * gts_heap_thaw:
+ * @heap: a #GtsHeap.
+ *
+ * If @heap has been frozen previously using gts_heap_freeze(), reorder it
+ * in O(n) time and unfreeze it.
+ */
+void gts_heap_thaw (GtsHeap * heap)
+{
+  guint i;
+  
+  g_return_if_fail (heap != NULL);
+
+  if (!heap->frozen)
+    return;
+
+  for (i = heap->elts->len/2; i > 0; i--)
+    sift_down (heap, i);
+
+  heap->frozen = FALSE;
+}
+
+/**
+ * gts_heap_foreach:
+ * @heap: a #GtsHeap.
+ * @func: the function to call for each element in the heap.
+ * @user_data: to pass to @func.
+ */
+void gts_heap_foreach (GtsHeap * heap, 
+		       GFunc func,
+		       gpointer user_data)
+{
+  guint i;
+  GPtrArray * elts;
+  
+  g_return_if_fail (heap != NULL);
+  g_return_if_fail (func != NULL);
+
+  elts = heap->elts;
+  for (i = 0; i < elts->len; i++)
+    (*func) (elts->pdata[i], user_data);
+}
+
+/**
+ * gts_heap_freeze:
+ * @heap: a #GtsHeap.
+ *
+ * Freezes the heap. Any subsequent operation will not preserve the heap
+ * property. Used in conjunction with gts_heap_insert() and gts_heap_thaw()
+ * to create a heap in O(n) time.
+ */
+void gts_heap_freeze (GtsHeap * heap)
+{
+  g_return_if_fail (heap != NULL);
+
+  heap->frozen = TRUE;
+}
+
+/**
+ * gts_heap_size:
+ * @heap: a #GtsHeap.
+ *
+ * Returns: the number of items in @heap.
+ */
+guint gts_heap_size (GtsHeap * heap)
+{
+  g_return_val_if_fail (heap != NULL, 0);
+
+  return heap->elts->len;
+}
diff --git a/gts/hsurface.c b/gts/hsurface.c
new file mode 100644
index 0000000..80ac66a
--- /dev/null
+++ b/gts/hsurface.c
@@ -0,0 +1,405 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include "gts.h"
+
+#define HEAP_INSERT_HSPLIT(h, e) ((e)->index = gts_eheap_insert (h, e))
+#define HEAP_REMOVE_HSPLIT(h, e) (gts_eheap_remove (h, (e)->index),\
+				  (e)->index = NULL)
+
+static void hsplit_init (GtsHSplit * hsplit)
+{
+  hsplit->index = NULL;
+  hsplit->parent = NULL;
+  hsplit->nchild = 0;
+}
+
+/**
+ * gts_hsplit_class:
+ *
+ * Returns: the #GtsHSplitClass.
+ */
+GtsHSplitClass * gts_hsplit_class (void)
+{
+  static GtsHSplitClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo hsplit_info = {
+      "GtsHSplit",
+      sizeof (GtsHSplit),
+      sizeof (GtsHSplitClass),
+      (GtsObjectClassInitFunc) NULL,
+      (GtsObjectInitFunc) hsplit_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_split_class ()), 
+				  &hsplit_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_hsplit_new:
+ * @klass: a #GtsHSplitClass.
+ * @vs: a #GtsSplit.
+ *
+ * Returns: a new #GtsHSplit, hierarchical extension of @vs.
+ */
+GtsHSplit * gts_hsplit_new (GtsHSplitClass * klass, GtsSplit * vs)
+{
+  GtsHSplit * hs;
+
+  g_return_val_if_fail (vs != NULL, NULL);
+
+  hs = GTS_HSPLIT (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  memcpy (hs, vs, sizeof (GtsSplit));
+  GTS_OBJECT (hs)->reserved = NULL;
+
+  return hs;
+}
+
+/**
+ * gts_hsplit_collapse:
+ * @hs: a #GtsHSplit.
+ * @hsurface: a #GtsHSurface.
+ *
+ * Collapses the #GtsSplit defined by @hs, updates the expandable and
+ * collapsable priority heaps of @hsurface.  
+ */
+void gts_hsplit_collapse (GtsHSplit * hs,
+			  GtsHSurface * hsurface)
+{
+  GtsHSplit * parent;
+  GtsSplit * vs;
+
+  g_return_if_fail (hs != NULL);
+  g_return_if_fail (hs->nchild == 2);
+  g_return_if_fail (hsurface != NULL);
+
+  gts_split_collapse (GTS_SPLIT (hs), hsurface->s->edge_class, NULL);
+
+  hsurface->nvertex--;
+  hs->nchild = 0;
+  HEAP_REMOVE_HSPLIT (hsurface->collapsable, hs);
+  HEAP_INSERT_HSPLIT (hsurface->expandable, hs);
+
+  vs = GTS_SPLIT (hs);
+  if (GTS_IS_HSPLIT (vs->v1))
+    HEAP_REMOVE_HSPLIT (hsurface->expandable, GTS_HSPLIT (vs->v1));
+  if (GTS_IS_HSPLIT (vs->v2))
+    HEAP_REMOVE_HSPLIT (hsurface->expandable, GTS_HSPLIT (vs->v2));
+
+  parent = hs->parent;
+  if (parent && ++parent->nchild == 2)
+    HEAP_INSERT_HSPLIT (hsurface->collapsable, parent);
+}
+
+/**
+ * gts_hsplit_expand:
+ * @hs: a #GtsHSplit.
+ * @hsurface: a #GtsHSurface.
+ *
+ * Expands the #GtsSplit defined by @hs (which must be expandable)
+ * and updates the priority heaps of @hsurface.
+ */
+void gts_hsplit_expand (GtsHSplit * hs,
+			GtsHSurface * hsurface)
+{
+  GtsHSplit * parent;
+  GtsSplit * vs;
+
+  g_return_if_fail (hs != NULL);
+  g_return_if_fail (hsurface != NULL);
+  g_return_if_fail (hs->nchild == 0);
+
+  gts_split_expand (GTS_SPLIT (hs), hsurface->s, hsurface->s->edge_class);
+  hsurface->nvertex++;
+  hs->nchild = 2;
+  HEAP_REMOVE_HSPLIT (hsurface->expandable, hs);
+  HEAP_INSERT_HSPLIT (hsurface->collapsable, hs);
+
+  vs = GTS_SPLIT (hs);
+  if (GTS_IS_HSPLIT (vs->v1))
+    HEAP_INSERT_HSPLIT (hsurface->expandable, GTS_HSPLIT (vs->v1));
+  if (GTS_IS_HSPLIT (vs->v2))
+    HEAP_INSERT_HSPLIT (hsurface->expandable, GTS_HSPLIT (vs->v2));
+
+  parent = hs->parent;
+  if (parent && parent->nchild-- == 2)
+    HEAP_REMOVE_HSPLIT (hsurface->collapsable, parent);
+}
+
+static void hsurface_destroy (GtsObject * object)
+{
+  GtsHSurface * hs = GTS_HSURFACE (object);
+
+  gts_hsurface_traverse (hs, G_POST_ORDER, -1,
+			 (GtsSplitTraverseFunc) gts_object_destroy, 
+			 NULL);
+  g_slist_free (hs->roots);
+  if (hs->expandable)
+    gts_eheap_destroy (hs->expandable);
+  if (hs->collapsable)
+    gts_eheap_destroy (hs->collapsable);
+  g_ptr_array_free (hs->split, TRUE);
+
+  (* GTS_OBJECT_CLASS (gts_hsurface_class ())->parent_class->destroy) (object);
+}
+
+static void hsurface_class_init (GtsObjectClass * klass)
+{
+  klass->destroy = hsurface_destroy;
+}
+
+static void hsurface_init (GtsHSurface * hsurface)
+{
+  hsurface->s = NULL;
+  hsurface->roots = NULL;
+  hsurface->expandable = hsurface->collapsable = NULL;
+  hsurface->split = g_ptr_array_new ();
+  hsurface->nvertex = 0;
+}
+
+/**
+ * gts_hsurface_class:
+ *
+ * Returns: the #GtsHSurfaceClass.
+ */
+GtsHSurfaceClass * gts_hsurface_class (void)
+{
+  static GtsHSurfaceClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo hsurface_info = {
+      "GtsHSurface",
+      sizeof (GtsHSurface),
+      sizeof (GtsHSurfaceClass),
+      (GtsObjectClassInitFunc) hsurface_class_init,
+      (GtsObjectInitFunc) hsurface_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (gts_object_class (), 
+				  &hsurface_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_hsurface_new:
+ * @klass: a #GtsHSurfaceClass.
+ * @hsplit_class: a #GtsHSplitClass.
+ * @psurface: a #GtsPSurface.
+ * @expand_key: a #GtsKeyFunc used to order the priority heap of expandable 
+ * #GtsHSplit.
+ * @expand_data: data to be passed to @expand_key.
+ * @collapse_key: a #GtsKeyFunc used to order the priority heap of collapsable
+ * #GtsHSplit.
+ * @collapse_data: data to be passed to @collapsed_key.
+ *
+ * Returns: a new #GtsHSurface, hierarchical extension of @psurface
+ * and using #GtsHSplit of class @hsplit_class. Note that @psurface is
+ * destroyed in the process.
+ */
+GtsHSurface * gts_hsurface_new (GtsHSurfaceClass * klass,
+				GtsHSplitClass * hsplit_class,
+				GtsPSurface * psurface,
+				GtsKeyFunc expand_key,
+				gpointer expand_data,
+				GtsKeyFunc collapse_key,
+				gpointer collapse_data)
+{
+  GtsHSurface * hsurface;
+
+  g_return_val_if_fail (klass != NULL, NULL);
+  g_return_val_if_fail (hsplit_class != NULL, NULL);
+  g_return_val_if_fail (psurface != NULL, NULL);
+  g_return_val_if_fail (expand_key != NULL, NULL);
+  g_return_val_if_fail (collapse_key != NULL, NULL);
+
+  hsurface = GTS_HSURFACE (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  hsurface->s = psurface->s;
+  hsurface->expandable = gts_eheap_new (expand_key, expand_data);
+  hsurface->collapsable = gts_eheap_new (collapse_key, collapse_data);
+  g_ptr_array_set_size (hsurface->split, psurface->split->len);
+
+  while (gts_psurface_remove_vertex (psurface))
+    ;
+  while (psurface->pos) {
+    GtsSplit * vs = g_ptr_array_index (psurface->split, psurface->pos - 1);
+    GtsHSplit * hs = gts_hsplit_new (hsplit_class, vs);
+
+    g_ptr_array_index (hsurface->split, psurface->pos - 1) = hs;
+    psurface->pos--;
+
+    hs->parent = GTS_OBJECT (vs)->reserved;
+    if (hs->parent) {
+      GtsSplit * vsp = GTS_SPLIT (hs->parent);
+
+      if (vsp->v1 == GTS_OBJECT (vs)) {
+	g_assert (vsp->v2 != GTS_OBJECT (vs));
+	vsp->v1 = GTS_OBJECT (hs);
+      }
+      else {
+	g_assert (vsp->v2 == GTS_OBJECT (vs));
+	vsp->v2 = GTS_OBJECT (hs);
+      }
+    }
+    else
+      hsurface->roots = g_slist_prepend (hsurface->roots, hs);
+
+    hs->nchild = 0;
+    if (GTS_IS_SPLIT (vs->v1))
+      GTS_OBJECT (vs->v1)->reserved = hs;
+    else
+      hs->nchild++;
+    if (GTS_IS_SPLIT (vs->v2))
+      GTS_OBJECT (vs->v2)->reserved = hs;
+    else
+      hs->nchild++;
+    
+    gts_split_expand (vs, psurface->s, psurface->s->edge_class);
+
+    if (hs->nchild == 2)
+      HEAP_INSERT_HSPLIT (hsurface->collapsable, hs);
+  }
+
+  hsurface->nvertex = gts_surface_vertex_number (hsurface->s);
+  gts_object_destroy (GTS_OBJECT (psurface));
+
+  return hsurface;
+}
+
+/**
+ * gts_hsurface_traverse:
+ * @hsurface: a #GtsHSurface.
+ * @order: the order in which nodes are visited - G_PRE_ORDER or G_POST_ORDER.
+ * @depth: the maximum depth of the traversal. Nodes below this depth
+ * will not be visited. If max_depth is -1 all nodes in the tree are
+ * visited. If depth is 1, only the root is visited. If depth is 2,
+ * the root and its children are visited. And so on.
+ * @func: the function to call for each visited #GtsHSplit.
+ * @data: user data to pass to the function.
+ *
+ * Traverses a hierarchical surface starting from its roots. It calls
+ * the given function for each #GtsHSplit visited. 
+ * See also gts_split_traverse().
+ */
+void gts_hsurface_traverse (GtsHSurface *    hsurface,
+			    GTraverseType    order,
+			    gint             depth,
+			    GtsSplitTraverseFunc func,
+			    gpointer         data)
+{
+  GSList * i;
+
+  g_return_if_fail (hsurface != NULL);
+  g_return_if_fail (func != NULL);
+  g_return_if_fail (order < G_LEVEL_ORDER);
+  g_return_if_fail (depth == -1 || depth > 0);
+
+  i = hsurface->roots;
+  while (i) {
+    gts_split_traverse (i->data, order, depth, func, data);
+    i = i->next;
+  }
+}
+
+/**
+ * gts_hsurface_foreach:
+ * @hsurface: a #GtsHSurface.
+ * @order: the order in which #GtsHSplit are visited - G_PRE_ORDER or 
+ * G_POST_ORDER.
+ * @func: the function to call for each visited #GtsHSplit.
+ * @data: user data to pass to the function.
+ *
+ * Starts by expanding all the #GtsHSplit of @hsurface. If @order is
+ * G_PRE_ORDER, calls @func for each #GtsHSplit and collapses it. If
+ * order is G_POST_ORDER, collapses each #GtsHSplit first and then
+ * calls @func. The traversal can be halted at any point by returning
+ * TRUE from func.  
+ */
+void gts_hsurface_foreach (GtsHSurface * hsurface,
+			   GTraverseType order,
+			   GtsFunc       func,
+			   gpointer      data)
+{
+  GtsHSplit * hs;
+  guint i = 0, len;
+  gboolean stop = FALSE;
+
+  g_return_if_fail (hsurface != NULL);
+  g_return_if_fail (func != NULL);
+  g_return_if_fail (order == G_PRE_ORDER || order == G_POST_ORDER);
+
+  while ((hs = gts_eheap_top (hsurface->expandable, NULL))) 
+    gts_hsplit_expand (hs, hsurface);
+
+  len = hsurface->split->len;
+  switch (order) {
+  case G_PRE_ORDER:
+    while (i < len && !stop) {
+      GtsHSplit * hs = g_ptr_array_index (hsurface->split, i);
+      stop = (*func) (hs, data);
+      if (!stop)
+	gts_hsplit_collapse (hs, hsurface);
+      i++;
+    }
+    break;
+  case G_POST_ORDER:
+    while (i < len && !stop) {
+      GtsHSplit * hs = g_ptr_array_index (hsurface->split, i);
+      gts_hsplit_collapse (hs, hsurface);
+      stop = (*func) (hs, data);
+      i++;
+    }
+    break;
+  default:
+    g_assert_not_reached ();
+  }
+}
+
+/**
+ * gts_hsurface_height:
+ * @hsurface: a #GtsHSurface.
+ *
+ * Returns: the maximum height of the tree described by @hsurface.
+ */
+guint gts_hsurface_height (GtsHSurface * hsurface)
+{
+  GSList * i;
+  guint height = 0;
+
+  g_return_val_if_fail (hsurface != NULL, 0);
+
+  i = hsurface->roots;
+  while (i) {
+    guint tmp_height = gts_split_height (i->data);
+    if (tmp_height > height)
+      height = tmp_height;
+    i = i->next;
+  }
+
+  return height;
+}
diff --git a/gts/iso.c b/gts/iso.c
new file mode 100644
index 0000000..5995a19
--- /dev/null
+++ b/gts/iso.c
@@ -0,0 +1,455 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "gts.h"
+
+typedef enum { LEFT = 0, RIGHT = 1 } Orientation;
+
+typedef struct {
+  GtsVertex * v;
+  Orientation orientation;
+} OrientedVertex;
+
+struct _GtsIsoSlice {
+  OrientedVertex *** vertices;
+  guint nx, ny;
+};
+
+/* coordinates of the edges of the cube (see doc/isocube.fig) */
+static guint c[12][4] = {
+  {0, 0, 0, 0}, {0, 0, 0, 1}, {0, 0, 1, 1}, {0, 0, 1, 0},
+  {1, 0, 0, 0}, {1, 0, 0, 1}, {1, 1, 0, 1}, {1, 1, 0, 0},
+  {2, 0, 0, 0}, {2, 1, 0, 0}, {2, 1, 1, 0}, {2, 0, 1, 0}};
+
+/* first index is the edge number, second index is the edge orientation 
+   (RIGHT or LEFT), third index are the edges which this edge may connect to
+   in order */
+static guint edge[12][2][3] = {
+  {{9, 1, 8}, {4, 3, 7}},   /* 0 */
+  {{6, 2, 5}, {8, 0, 9}},   /* 1 */
+  {{10, 3, 11}, {5, 1, 6}}, /* 2 */
+  {{7, 0, 4}, {11, 2, 10}}, /* 3 */
+  {{3, 7, 0}, {8, 5, 11}},  /* 4 */
+  {{11, 4, 8}, {1, 6, 2}},  /* 5 */
+  {{2, 5, 1}, {9, 7, 10}},  /* 6 */
+  {{10, 6, 9}, {0, 4, 3}},  /* 7 */
+  {{5, 11, 4}, {0, 9, 1}},  /* 8 */
+  {{1, 8, 0}, {7, 10, 6}},  /* 9 */
+  {{6, 9, 7}, {3, 11, 2}},  /* 10 */
+  {{2, 10, 3}, {4, 8, 5}}   /* 11 */
+};
+
+static void ** malloc2D (guint nx, guint ny, gulong size)
+{
+  void ** m = g_malloc (nx*sizeof (void *));
+  guint i;
+
+  for (i = 0; i < nx; i++)
+    m[i] = g_malloc0 (ny*size);
+
+  return m;
+}
+
+static void free2D (void ** m, guint nx)
+{
+  guint i;
+
+  g_return_if_fail (m != NULL);
+
+  for (i = 0; i < nx; i++)
+    g_free (m[i]);
+  g_free (m);
+}
+
+/**
+ * gts_grid_plane_new:
+ * @nx:
+ * @ny:
+ *
+ * Returns:
+ */
+GtsGridPlane * gts_grid_plane_new (guint nx, guint ny)
+{
+  GtsGridPlane * g = g_malloc (sizeof (GtsGridPlane));
+
+  g->p = (GtsPoint **) malloc2D (nx, ny, sizeof (GtsPoint));
+  g->nx = nx;
+  g->ny = ny;
+  
+  return g;
+}
+
+/**
+ * gts_grid_plane_destroy:
+ * @g:
+ *
+ */
+void gts_grid_plane_destroy (GtsGridPlane * g)
+{
+  g_return_if_fail (g != NULL);
+
+  free2D ((void **) g->p, g->nx);
+  g_free (g);
+}
+
+/**
+ * gts_iso_slice_new:
+ * @nx: number of vertices in the x direction.
+ * @ny: number of vertices in the y direction.
+ *
+ * Returns: a new #GtsIsoSlice.
+ */
+GtsIsoSlice * gts_iso_slice_new (guint nx, guint ny)
+{
+  GtsIsoSlice * slice;
+
+  g_return_val_if_fail (nx > 1, NULL);
+  g_return_val_if_fail (ny > 1, NULL);
+
+  slice = g_malloc (sizeof (GtsIsoSlice));
+
+  slice->vertices = g_malloc (3*sizeof (OrientedVertex **));
+  slice->vertices[0] = 
+    (OrientedVertex **) malloc2D (nx, ny, sizeof (OrientedVertex));
+  slice->vertices[1] = 
+    (OrientedVertex **) malloc2D (nx - 1, ny, sizeof (OrientedVertex));
+  slice->vertices[2] = 
+    (OrientedVertex **) malloc2D (nx, ny - 1, sizeof (OrientedVertex));
+  slice->nx = nx;
+  slice->ny = ny;
+
+  return slice;
+}
+
+/**
+ * gts_iso_slice_fill:
+ * @slice: a #GtsIsoSlice.
+ * @plane1: a #GtsGridPlane.
+ * @plane2: another #GtsGridPlane.
+ * @f1: values of the function corresponding to @plane1.
+ * @f2: values of the function corresponding to @plane2.
+ * @iso: isosurface value.
+ * @klass: a #GtsVertexClass or one of its descendant to be used for the 
+ * new vertices.
+ *
+ * Fill @slice with the coordinates of the vertices defined by 
+ * f1 (x,y,z) = @iso and f2 (x, y, z) = @iso.
+ */
+void gts_iso_slice_fill (GtsIsoSlice * slice,
+			 GtsGridPlane * plane1,
+			 GtsGridPlane * plane2,
+			 gdouble ** f1,
+			 gdouble ** f2,
+			 gdouble iso,
+			 GtsVertexClass * klass)
+{
+  OrientedVertex *** vertices;
+  GtsPoint ** p1, ** p2 = NULL;
+  guint i, j, nx, ny;
+
+  g_return_if_fail (slice != NULL);
+  g_return_if_fail (plane1 != NULL);
+  g_return_if_fail (f1 != NULL);
+  g_return_if_fail (f2 == NULL || plane2 != NULL);
+
+  p1 = plane1->p;
+  if (plane2) 
+    p2 = plane2->p;
+  vertices = slice->vertices;
+  nx = slice->nx;
+  ny = slice->ny;
+
+  if (f2)
+    for (i = 0; i < nx; i++)
+      for (j = 0; j < ny; j++) {
+	gdouble v1 = f1[i][j] - iso;
+	gdouble v2 = f2[i][j] - iso;
+	if ((v1 >= 0. && v2 < 0.) || (v1 < 0. && v2 >= 0.)) {
+	  gdouble c2 = v1/(v1 - v2), c1 = 1. - c2;
+	  vertices[0][i][j].v = 
+	    gts_vertex_new (klass,
+			    c1*p1[i][j].x + c2*p2[i][j].x,
+			    c1*p1[i][j].y + c2*p2[i][j].y,
+			    c1*p1[i][j].z + c2*p2[i][j].z);
+	  vertices[0][i][j].orientation = v2 >= 0. ? RIGHT : LEFT;
+	}
+	else
+	  vertices[0][i][j].v = NULL;
+      }
+  for (i = 0; i < nx - 1; i++)
+    for (j = 0; j < ny; j++) {
+      gdouble v1 = f1[i][j] - iso;
+      gdouble v2 = f1[i+1][j] - iso;
+      if ((v1 >= 0. && v2 < 0.) || (v1 < 0. && v2 >= 0.)) {
+	gdouble c2 = v1/(v1 - v2), c1 = 1. - c2;
+	vertices[1][i][j].v = 
+	  gts_vertex_new (klass,
+			  c1*p1[i][j].x + c2*p1[i+1][j].x,
+			  c1*p1[i][j].y + c2*p1[i+1][j].y,
+			  c1*p1[i][j].z + c2*p1[i+1][j].z);
+	vertices[1][i][j].orientation = v2 >= 0. ? RIGHT : LEFT;
+      }
+      else
+	vertices[1][i][j].v = NULL;
+    }
+  for (i = 0; i < nx; i++)
+    for (j = 0; j < ny - 1; j++) {
+      gdouble v1 = f1[i][j] - iso;
+      gdouble v2 = f1[i][j+1] - iso;
+      if ((v1 >= 0. && v2 < 0.) || (v1 < 0. && v2 >= 0.)) {
+	gdouble c2 = v1/(v1 - v2), c1 = 1. - c2;
+	vertices[2][i][j].v = 
+	  gts_vertex_new (klass,
+			  c1*p1[i][j].x + c2*p1[i][j+1].x,
+			  c1*p1[i][j].y + c2*p1[i][j+1].y,
+			  c1*p1[i][j].z + c2*p1[i][j+1].z);
+	vertices[2][i][j].orientation = v2 >= 0. ? RIGHT : LEFT;
+      }
+      else
+	vertices[2][i][j].v = NULL;
+    }
+}
+ 
+/**
+ * gts_iso_slice_fill_cartesian:
+ * @slice: a #GtsIsoSlice.
+ * @g: a #GtsCartesianGrid.
+ * @f1: values of the function for plane z = @g.z.
+ * @f2: values of the function for plane z = @g.z + @g.dz.
+ * @iso: isosurface value.
+ * @klass: a #GtsVertexClass.
+ *
+ * Fill @slice with the coordinates of the vertices defined by 
+ * f1 (x,y,z) = @iso and f2 (x, y, z) = @iso.
+ */
+void gts_iso_slice_fill_cartesian (GtsIsoSlice * slice,
+				   GtsCartesianGrid g,
+				   gdouble ** f1,
+				   gdouble ** f2,
+				   gdouble iso,
+				   GtsVertexClass * klass)
+{
+  OrientedVertex *** vertices;
+  guint i, j;
+  gdouble x, y;
+
+  g_return_if_fail (slice != NULL);
+  g_return_if_fail (f1 != NULL);
+
+  vertices = slice->vertices;
+
+  if (f2)
+    for (i = 0, x = g.x; i < g.nx; i++, x += g.dx)
+      for (j = 0, y = g.y; j < g.ny; j++, y += g.dy) {
+	gdouble v1 = f1[i][j] - iso;
+	gdouble v2 = f2[i][j] - iso;
+	if ((v1 >= 0. && v2 < 0.) || (v1 < 0. && v2 >= 0.)) {
+	  vertices[0][i][j].v = 
+	    gts_vertex_new (klass,
+			    x, y, g.z + g.dz*v1/(v1 - v2));
+	  vertices[0][i][j].orientation = v2 >= 0. ? RIGHT : LEFT;
+	}
+	else
+	  vertices[0][i][j].v = NULL;
+      }
+  for (i = 0, x = g.x; i < g.nx - 1; i++, x += g.dx)
+    for (j = 0, y = g.y; j < g.ny; j++, y += g.dy) {
+      gdouble v1 = f1[i][j] - iso;
+      gdouble v2 = f1[i+1][j] - iso;
+      if ((v1 >= 0. && v2 < 0.) || (v1 < 0. && v2 >= 0.)) {
+	vertices[1][i][j].v = 
+	  gts_vertex_new (klass, x + g.dx*v1/(v1 - v2), y, g.z);
+	vertices[1][i][j].orientation = v2 >= 0. ? RIGHT : LEFT;
+      }
+      else
+	vertices[1][i][j].v = NULL;
+    }
+  for (i = 0, x = g.x; i < g.nx; i++, x += g.dx)
+    for (j = 0, y = g.y; j < g.ny - 1; j++, y += g.dy) {
+      gdouble v1 = f1[i][j] - iso;
+      gdouble v2 = f1[i][j+1] - iso;
+      if ((v1 >= 0. && v2 < 0.) || (v1 < 0. && v2 >= 0.)) {
+	vertices[2][i][j].v = 
+	  gts_vertex_new (klass, x, y + g.dy*v1/(v1 - v2), g.z);
+	vertices[2][i][j].orientation = v2 >= 0. ? RIGHT : LEFT;
+      }
+      else
+	vertices[2][i][j].v = NULL;
+    }
+}
+
+/**
+ * gts_iso_slice_destroy:
+ * @slice: a #GtsIsoSlice.
+ *
+ * Free all memory allocated for @slice.
+ */
+void gts_iso_slice_destroy (GtsIsoSlice * slice)
+{
+  g_return_if_fail (slice != NULL);
+
+  free2D ((void **) slice->vertices[0], slice->nx);
+  free2D ((void **) slice->vertices[1], slice->nx - 1);
+  free2D ((void **) slice->vertices[2], slice->nx);  
+  g_free (slice->vertices);
+  g_free (slice);
+}
+
+/**
+ * gts_isosurface_slice:
+ * @slice1: a #GtsIsoSlice.
+ * @slice2: another #GtsIsoSlice.
+ * @surface: a #GtsSurface.
+ *
+ * Given two successive slices @slice1 and @slice2 link their vertices with
+ * segments and triangles which are added to @surface.
+ */
+void gts_isosurface_slice (GtsIsoSlice * slice1,
+			   GtsIsoSlice * slice2,
+			   GtsSurface * surface)
+{
+  guint j, k, l, nx, ny;
+  OrientedVertex *** vertices[2];
+  GtsVertex * va[12];
+
+  g_return_if_fail (slice1 != NULL);
+  g_return_if_fail (slice2 != NULL);
+  g_return_if_fail (surface != NULL);
+  g_return_if_fail (slice1->nx == slice2->nx && slice1->ny == slice2->ny);
+
+  vertices[0] = slice1->vertices;
+  vertices[1] = slice2->vertices;
+  nx = slice1->nx;
+  ny = slice1->ny;
+
+  /* link vertices with segments and triangles */
+  for (j = 0; j < nx - 1; j++)
+    for (k = 0; k < ny - 1; k++) {
+      gboolean cube_is_cut = FALSE;
+      for (l = 0; l < 12; l++) {
+	guint nv = 0, e = l;
+	OrientedVertex ov = 
+	  vertices[c[e][1]][c[e][0]][j + c[e][2]][k + c[e][3]];
+	while (ov.v && !GTS_OBJECT (ov.v)->reserved) {
+	  guint m = 0, * ne = edge[e][ov.orientation];
+	  va[nv++] = ov.v;
+	  GTS_OBJECT (ov.v)->reserved = surface;
+	  ov.v = NULL;
+	  while (m < 3 && !ov.v) {
+	    e = ne[m++];
+	    ov = vertices[c[e][1]][c[e][0]][j + c[e][2]][k + c[e][3]];
+	  }
+	}
+	/* create edges and faces */
+	if (nv > 2) {
+	  GtsEdge * e1, * e2, * e3;
+	  guint m;
+	  if (!(e1 = GTS_EDGE (gts_vertices_are_connected (va[0], va[1]))))
+	    e1 = gts_edge_new (surface->edge_class, va[0], va[1]);
+	  for (m = 1; m < nv - 1; m++) {
+	    if (!(e2 = GTS_EDGE (gts_vertices_are_connected (va[m], va[m+1]))))
+	      e2 = gts_edge_new (surface->edge_class, va[m], va[m+1]);
+	    if (!(e3 = GTS_EDGE (gts_vertices_are_connected (va[m+1], va[0]))))
+	      e3 = gts_edge_new (surface->edge_class, va[m+1], va[0]);
+	    gts_surface_add_face (surface, 
+				  gts_face_new (surface->face_class,
+						e1, e2, e3));
+	    e1 = e3;
+	  }
+	}
+	if (nv > 0)
+	  cube_is_cut = TRUE;
+      }
+      if (cube_is_cut)
+	for (l = 0; l < 12; l++) {
+	  GtsVertex * v = 
+	    vertices[c[l][1]][c[l][0]][j + c[l][2]][k + c[l][3]].v;
+	  if (v)
+	    GTS_OBJECT (v)->reserved = NULL;
+	}
+    }
+}
+
+#define SWAP(s1, s2, tmp) (tmp = s1, s1 = s2, s2 = tmp)
+
+/**
+ * gts_isosurface_cartesian:
+ * @surface: a #GtsSurface.
+ * @g: a #GtsCartesianGrid.
+ * @f: a #GtsIsoCartesianFunc.
+ * @data: user data to be passed to @f.
+ * @iso: isosurface value.
+ *
+ * Adds to @surface new faces defining the isosurface f(x,y,z) = @iso. By
+ * convention, the normals to the surface are pointing toward the positive
+ * values of f(x,y,z) - @iso.
+ *
+ * The user function @f is called successively for each value of the z 
+ * coordinate defined by @g. It must fill the corresponding (x,y) plane with
+ * the values of the function for which the isosurface is to be computed.
+ */
+void gts_isosurface_cartesian (GtsSurface * surface,
+			       GtsCartesianGrid g,
+			       GtsIsoCartesianFunc f,
+			       gpointer data,
+			       gdouble iso)
+{
+  void * tmp;
+  gdouble ** f1, ** f2;
+  GtsIsoSlice * slice1, * slice2;
+  guint i;
+
+  g_return_if_fail (surface != NULL);
+  g_return_if_fail (f != NULL);
+  g_return_if_fail (g.nx > 1);
+  g_return_if_fail (g.ny > 1);
+  g_return_if_fail (g.nz > 1);
+
+  slice1 = gts_iso_slice_new (g.nx, g.ny);
+  slice2 = gts_iso_slice_new (g.nx, g.ny);
+  f1 = (gdouble **) malloc2D (g.nx, g.ny, sizeof (gdouble));
+  f2 = (gdouble **) malloc2D (g.nx, g.ny, sizeof (gdouble));
+
+  (*f) (f1, g, 0, data);
+  g.z += g.dz;
+  (*f) (f2, g, 1, data);
+  g.z -= g.dz;
+  gts_iso_slice_fill_cartesian (slice1, g, f1, f2, iso, 
+				surface->vertex_class);
+  g.z += g.dz;
+  for (i = 2; i < g.nz; i++) {
+    g.z += g.dz;
+    (*f) (f1, g, i, data);
+    SWAP (f1, f2, tmp);
+    g.z -= g.dz;
+    gts_iso_slice_fill_cartesian (slice2, g, f1, f2, iso, 
+				  surface->vertex_class);
+    g.z += g.dz;
+    gts_isosurface_slice (slice1, slice2, surface);
+    SWAP (slice1, slice2, tmp);
+  }
+  gts_iso_slice_fill_cartesian (slice2, g, f2, NULL, iso,
+				surface->vertex_class);
+  gts_isosurface_slice (slice1, slice2, surface);
+
+  gts_iso_slice_destroy (slice1);
+  gts_iso_slice_destroy (slice2);
+  free2D ((void **) f1, g.nx);
+  free2D ((void **) f2, g.nx);
+}
diff --git a/gts/isotetra.c b/gts/isotetra.c
new file mode 100644
index 0000000..35fe2ba
--- /dev/null
+++ b/gts/isotetra.c
@@ -0,0 +1,840 @@
+/* GTS-Library conform marching tetrahedra algorithm 
+ * Copyright (C) 2002 Gert Wollny
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <math.h>
+#include <string.h>
+#include <gts.h>
+#ifdef NATIVE_WIN32
+# include <memory.h>
+# define M_SQRT2		1.41421356237309504880
+#endif /* NATIVE_WIN32 */
+
+typedef struct {
+  gint nx, ny; 
+  gdouble ** data; 
+} slice_t;
+
+typedef struct {
+  gint x, y, z;
+  gboolean mid;
+  gdouble d; 
+} tetra_vertex_t; 
+
+/* this helper is a lookup table for vertices */
+typedef struct {
+  gint nx, ny; 
+  GtsVertex ** vtop, ** vmid, **vbot;
+} helper_t ;
+
+typedef struct {
+  GHashTable * vbot, * vtop;
+} helper_bcl ;
+
+
+static helper_t * init_helper (int nx, int ny) 
+{
+  gint nxy = 4*nx*ny; 
+  helper_t *retval = g_malloc0 (sizeof (helper_t));
+
+  retval->nx = nx; 
+  retval->ny = ny; 
+  retval->vtop = g_malloc0 (sizeof (GtsVertex *)*nxy);
+  retval->vmid = g_malloc0 (sizeof (GtsVertex *)*nxy);
+  retval->vbot = g_malloc0 (sizeof (GtsVertex *)*nxy);
+  return retval;
+}
+
+static helper_bcl * init_helper_bcl (void)
+{
+  helper_bcl *retval = g_malloc0 (sizeof (helper_bcl));
+
+  retval->vtop = g_hash_table_new (g_str_hash, g_str_equal);
+  retval->vbot = g_hash_table_new (g_str_hash, g_str_equal);
+  return retval;
+}
+
+static void free_helper (helper_t * h) 
+{
+  g_free (h->vtop);
+  g_free (h->vmid);
+  g_free (h->vbot);
+  g_free (h);
+}
+
+static void free_helper_bcl (helper_bcl * h) 
+{
+  g_hash_table_destroy (h->vtop);
+  g_hash_table_destroy (h->vbot);
+  g_free (h);
+}
+
+/* move the vertices in the bottom slice to the top, and clear the
+   other slices in the lookup tables */
+static void helper_advance (helper_t * h) 
+{
+  GtsVertex ** help = h->vbot;
+  h->vbot = h->vtop; 
+  h->vtop = help;
+  
+  memset (h->vmid, 0, 4*sizeof(GtsVertex *) * h->nx * h->ny);
+  memset (h->vbot, 0, 4*sizeof(GtsVertex *) * h->nx * h->ny);
+}
+
+static void helper_advance_bcl (helper_bcl * h) 
+{
+  GHashTable * help = g_hash_table_new (g_str_hash, g_str_equal);
+
+  g_hash_table_destroy (h->vbot);
+  h->vbot = h->vtop;
+  h->vtop = help;
+}
+
+/* find the zero-crossing of line through v1 and v2 and return the
+   corresponding GtsVertex */
+static GtsVertex * get_vertex (gint mz, 
+			       const tetra_vertex_t * v1, 
+			       const tetra_vertex_t * v2, 
+			       helper_t * help, 
+			       GtsCartesianGrid * g,
+			       GtsVertexClass * klass)
+{
+  GtsVertex ** vertex; 
+  gint x, y, index, idx2, z; 
+  gdouble dx, dy, dz, d; 
+
+  g_assert (v1->d - v2->d != 0.);
+  
+  dx = dy = dz = 0.0;
+  d = v1->d/(v1->d - v2->d);
+
+  index = 0;
+  
+  if (v1->x != v2->x) {
+    index |= 1;
+    dx = d;
+  }
+  
+  if (v1->y != v2->y) {
+    index |= 2;
+    dy = d;
+  }
+  
+  if (v1->z != v2->z) {
+    dz = d;
+  }
+
+  x = v1->x;
+  if (v1->x > v2->x) {  x = v2->x; dx = 1.0 - dx; }
+  
+  y = v1->y;
+  if (v1->y > v2->y) {  y = v2->y; dy = 1.0 - dy;}
+  
+  z = v1->z;
+  if (v1->z > v2->z) {  z = v2->z; dz = 1.0 - dz;}
+  
+  idx2 = 4 * ( x + y * help->nx ) + index;
+  
+  if (v1->z == v2->z)
+    vertex = (mz == z) ? &help->vtop[idx2] : &help->vbot[idx2];
+  else
+    vertex = &help->vmid[idx2];
+  
+  if (mz != z && dz != 0.0) {
+    fprintf(stderr, "%f \n", dz);
+  }
+  
+  /* if vertex is not yet created, do it now */
+  if (!*vertex)
+    *vertex = gts_vertex_new (klass,
+			      g->dx * ( x + dx) + g->x, 
+			      g->dy * ( y + dy) + g->y, 
+			      g->dz * ( z + dz) + g->z);
+  
+  return *vertex;
+}
+
+static GtsVertex * get_vertex_bcl (gint mz, 
+				   const tetra_vertex_t * v1, 
+				   const tetra_vertex_t * v2, 
+				   helper_bcl * help, 
+				   GtsCartesianGrid * g,
+				   GtsVertexClass * klass)
+{
+  GtsVertex * v;
+  GHashTable * table;
+  gchar * s1, * s2, * hash;
+  gdouble x1, x2, y1, y2, z1, z2, d;
+
+  g_assert (v1->d - v2->d != 0.);
+
+  /* first find correct hash table */  
+  if ((v1->z > mz) && (v2->z > mz))
+    table = help->vtop;
+  else
+    table = help->vbot;
+
+  d = v1->d / (v1->d - v2->d);
+
+  /* sort vertices */
+  s1 = g_strdup_printf ("%d %d %d %d", v1->x, v1->y, v1->z, v1->mid);
+  s2 = g_strdup_printf ("%d %d %d %d", v2->x, v2->y, v2->z, v2->mid);
+
+  hash = (d == 0.0) ? g_strdup (s1) :
+    (d == 1.0) ? g_strdup (s2) :
+    (strcmp (s1, s2) < 0) ? g_strjoin (" ", s1, s2, NULL) :
+    g_strjoin (" ", s2, s1, NULL);
+
+  /* return existing vertex or make a new one */
+  v = g_hash_table_lookup (table, hash);
+  if (!v){
+
+    x1 = g->dx * (v1->x + (v1->mid / 2.0)) + g->x;
+    x2 = g->dx * (v2->x + (v2->mid / 2.0)) + g->x;
+    y1 = g->dy * (v1->y + (v1->mid / 2.0)) + g->y;
+    y2 = g->dy * (v2->y + (v2->mid / 2.0)) + g->y;
+    z1 = g->dz * (v1->z + (v1->mid / 2.0)) + g->z;
+    z2 = g->dz * (v2->z + (v2->mid / 2.0)) + g->z;
+
+    v = gts_vertex_new (klass, x1 * (1.0 - d) + d * x2,
+			y1 * (1.0 - d) + d * y2,
+			z1 * (1.0 - d) + d * z2);
+
+    g_hash_table_insert (table, g_strdup(hash), v);
+  }
+  g_free (s1);
+  g_free (s2);
+  g_free (hash);
+
+  return v;
+}
+
+/* create an edge connecting the zero crossings of lines through a
+   pair of vertices, or return an existing one */
+static GtsEdge * get_edge (GtsVertex * v1, GtsVertex * v2,
+			   GtsEdgeClass * klass)
+{
+  GtsSegment *s;
+  GtsEdge *edge; 
+  
+  g_assert (v1);
+  g_assert (v2);
+  
+  s = gts_vertices_are_connected (v1, v2);
+  
+  if (GTS_IS_EDGE (s))
+    edge = GTS_EDGE(s);
+  else
+    edge = gts_edge_new (klass, v1, v2);
+  return edge; 
+}
+
+static void add_face (GtsSurface * surface, 
+		      const tetra_vertex_t * a1, const tetra_vertex_t * a2, 
+		      const tetra_vertex_t * b1, const tetra_vertex_t * b2, 
+		      const tetra_vertex_t * c1, const tetra_vertex_t * c2, 
+		      gint rev, helper_t * help, 
+		      gint z, GtsCartesianGrid * g)
+{
+  GtsFace * t; 
+  GtsEdge * e1, * e2, * e3; 	
+  GtsVertex * v1 = get_vertex (z, a1, a2, help, g, surface->vertex_class);
+  GtsVertex * v2 = get_vertex (z, b1, b2, help, g, surface->vertex_class);
+  GtsVertex * v3 = get_vertex (z, c1, c2, help, g, surface->vertex_class);
+
+  g_assert (v1 != v2);
+  g_assert (v2 != v3);
+  g_assert (v1 != v3);
+
+  if (!rev) {
+    e1 = get_edge (v1, v2, surface->edge_class);
+    e2 = get_edge (v2, v3, surface->edge_class);
+    e3 = get_edge (v1, v3, surface->edge_class);
+  } else {
+    e1 = get_edge (v1, v3, surface->edge_class);
+    e2 = get_edge (v2, v3, surface->edge_class);
+    e3 = get_edge (v1, v2, surface->edge_class);	
+  }
+  
+  t = gts_face_new (surface->face_class, e1, e2, e3);	
+  gts_surface_add_face (surface, t);
+}
+
+static void add_face_bcl (GtsSurface * surface, 
+			  const tetra_vertex_t * a1, 
+			  const tetra_vertex_t * a2, 
+			  const tetra_vertex_t * b1, 
+			  const tetra_vertex_t * b2, 
+			  const tetra_vertex_t * c1, 
+			  const tetra_vertex_t * c2, 
+			  gint rev, helper_bcl * help, 
+			  gint z, GtsCartesianGrid * g)
+{
+  GtsFace * t; 
+  GtsEdge * e1, * e2, * e3; 	
+  GtsVertex * v1 = get_vertex_bcl (z, a1, a2, help, g, surface->vertex_class);
+  GtsVertex * v2 = get_vertex_bcl (z, b1, b2, help, g, surface->vertex_class);
+  GtsVertex * v3 = get_vertex_bcl (z, c1, c2, help, g, surface->vertex_class);
+
+  if (v1 == v2 || v2 == v3 || v1 == v3)
+    return;
+
+  if (!rev) {
+    e1 = get_edge (v1, v2, surface->edge_class);
+    e2 = get_edge (v2, v3, surface->edge_class);
+    e3 = get_edge (v1, v3, surface->edge_class);
+  } else {
+    e1 = get_edge (v1, v3, surface->edge_class);
+    e2 = get_edge (v2, v3, surface->edge_class);
+    e3 = get_edge (v1, v2, surface->edge_class);	
+  }
+
+  t = gts_face_new (surface->face_class, e1, e2, e3);	
+  gts_surface_add_face (surface, t);
+}
+
+/* create a new slice of site nx \times ny */
+static slice_t * new_slice (gint nx, gint ny) 
+{
+  gint x; 
+  slice_t * retval = g_malloc (sizeof (slice_t));
+
+  retval->data = g_malloc (nx*sizeof(gdouble *));
+  retval->nx = nx;
+  retval->ny = ny;  
+  for (x = 0; x < nx; x++) 
+    retval->data[x] = g_malloc (ny*sizeof (gdouble));
+  return retval; 
+}
+
+/* initialize a slice with inival */
+static void slice_init (slice_t * slice, gdouble inival)
+{
+  gint x, y; 
+  
+  g_assert (slice);
+	
+  for (x = 0; x < slice->nx; x++) 
+    for (y = 0; y < slice->ny; y++)
+      slice->data[x][y] = inival; 
+}
+
+/* free the memory of a slice */
+static void free_slice (slice_t * slice) 
+{
+  gint x; 
+	
+  g_return_if_fail (slice != NULL);
+	
+  for (x = 0; x < slice->nx; x++) 
+    g_free (slice->data[x]);  
+  g_free (slice->data);
+  g_free (slice);
+}
+
+static void analyze_tetrahedra (const tetra_vertex_t * a, 
+				const tetra_vertex_t * b, 
+				const tetra_vertex_t * c, 
+				const tetra_vertex_t * d, 
+				gint parity, GtsSurface * surface, 
+				helper_t * help, 
+				gint z, GtsCartesianGrid * g)
+{
+  gint rev = parity; 
+  gint code = 0; 
+	
+  if (a->d >= 0.) code |= 1; 
+  if (b->d >= 0.) code |= 2; 
+  if (c->d >= 0.) code |= 4; 
+  if (d->d >= 0.) code |= 8;
+		
+  switch (code) {
+  case 15:
+  case 0: return; /* all inside or outside */		
+  
+  case 14:rev = !parity;
+  case  1:add_face (surface, a, b, a, d, a, c, rev, help, z, g);
+	  break;
+  case 13:rev = ! parity;  
+  case  2:add_face (surface, a, b, b, c, b, d, rev, help, z, g);
+	  break;
+  case 12:rev = !parity;	  
+  case  3:add_face (surface, a, d, a, c, b, c, rev, help, z, g);
+	  add_face (surface, a, d, b, c, b, d, rev, help, z, g);
+	  break;
+  case 11:rev = !parity;	  
+  case  4:add_face (surface, a, c, c, d, b, c, rev, help, z, g);
+	  break;
+  case 10:rev = !parity; 	  
+  case 5: add_face (surface, a, b, a, d, c, d, rev, help, z, g);
+	  add_face (surface, a, b, c, d, b, c, rev, help, z, g);
+	  break;	
+  case  9:rev = !parity; 
+  case  6:add_face (surface, a, b, a, c, c, d, rev, help, z, g);
+	  add_face (surface, a, b, c, d, b, d, rev, help, z, g);
+	  break;
+  case  7:rev = !parity;
+  case  8:add_face (surface, a, d, b, d, c, d, rev, help, z, g);
+    break; 
+  }
+}
+
+static void analyze_tetrahedra_bcl (const tetra_vertex_t * a, 
+				    const tetra_vertex_t * b, 
+				    const tetra_vertex_t * c, 
+				    const tetra_vertex_t * d, 
+				    GtsSurface * surface, 
+				    helper_bcl * help, 
+				    gint z, GtsCartesianGrid * g)
+{
+  gint rev = 0;
+  gint code = 0; 
+	
+  if (a->d >= 0.) code |= 1; 
+  if (b->d >= 0.) code |= 2; 
+  if (c->d >= 0.) code |= 4; 
+  if (d->d >= 0.) code |= 8;
+
+  switch (code) {
+  case 15:
+  case 0: return; /* all inside or outside */		
+
+  case 14:rev = !rev;
+  case  1:add_face_bcl (surface, a, b, a, d, a, c, rev, help, z, g);
+	  break;
+  case 13:rev = !rev;  
+  case  2:add_face_bcl (surface, a, b, b, c, b, d, rev, help, z, g);
+	  break;
+  case 12:rev = !rev;	  
+  case  3:add_face_bcl (surface, a, d, a, c, b, c, rev, help, z, g);
+	  add_face_bcl (surface, a, d, b, c, b, d, rev, help, z, g);
+	  break;
+  case 11:rev = !rev;	  
+  case  4:add_face_bcl (surface, a, c, c, d, b, c, rev, help, z, g);
+	  break;
+  case 10:rev = !rev; 	  
+  case 5: add_face_bcl (surface, a, b, a, d, c, d, rev, help, z, g);
+	  add_face_bcl (surface, a, b, c, d, b, c, rev, help, z, g);
+	  break;	
+  case  9:rev = !rev; 
+  case  6:add_face_bcl (surface, a, b, a, c, c, d, rev, help, z, g);
+	  add_face_bcl (surface, a, b, c, d, b, d, rev, help, z, g);
+	  break;
+  case  7:rev = !rev;
+  case  8:add_face_bcl (surface, a, d, b, d, c, d, rev, help, z, g);
+    break;
+  }
+}
+
+static void  iso_slice_evaluate (slice_t * s1, slice_t * s2, 
+				 GtsCartesianGrid g, 
+				 gint z, GtsSurface * surface, helper_t * help)
+{
+  gint x,y; 
+  tetra_vertex_t v0, v1, v2, v3, v4, v5, v6, v7; 
+  gdouble ** s1p = s1->data; 
+  gdouble ** s2p = s2->data; 
+	
+  for (y = 0; y < g.ny-1; y++)
+    for (x = 0; x < g.nx-1; x++) {
+      gint parity = (((x ^ y) ^ z) & 1);
+      
+      v0.x = x  ; v0.y = y  ; v0.z = z  ; v0.mid = FALSE; v0.d = s1p[x  ][y  ];
+      v1.x = x  ; v1.y = y+1; v1.z = z  ; v1.mid = FALSE; v1.d = s1p[x  ][y+1];
+      v2.x = x+1; v2.y = y  ; v2.z = z  ; v2.mid = FALSE; v2.d = s1p[x+1][y  ];
+      v3.x = x+1; v3.y = y+1; v3.z = z  ; v3.mid = FALSE; v3.d = s1p[x+1][y+1];
+      v4.x = x  ; v4.y = y  ; v4.z = z+1; v4.mid = FALSE; v4.d = s2p[x  ][y  ];
+      v5.x = x  ; v5.y = y+1; v5.z = z+1; v5.mid = FALSE; v5.d = s2p[x  ][y+1];
+      v6.x = x+1; v6.y = y  ; v6.z = z+1; v6.mid = FALSE; v6.d = s2p[x+1][y  ];
+      v7.x = x+1; v7.y = y+1; v7.z = z+1; v7.mid = FALSE; v7.d = s2p[x+1][y+1];
+      
+      if (parity == 0) {
+	analyze_tetrahedra (&v0, &v1, &v2, &v4, parity, surface, help, z, &g);
+	analyze_tetrahedra (&v7, &v1, &v4, &v2, parity, surface, help, z, &g);
+	analyze_tetrahedra (&v1, &v7, &v3, &v2, parity, surface, help, z, &g);
+	analyze_tetrahedra (&v1, &v7, &v4, &v5, parity, surface, help, z, &g);
+	analyze_tetrahedra (&v2, &v6, &v4, &v7, parity, surface, help, z, &g);
+      }else{
+	analyze_tetrahedra (&v4, &v5, &v6, &v0, parity, surface, help, z, &g);
+	analyze_tetrahedra (&v3, &v5, &v0, &v6, parity, surface, help, z, &g);
+	analyze_tetrahedra (&v5, &v3, &v7, &v6, parity, surface, help, z, &g);
+	analyze_tetrahedra (&v5, &v3, &v0, &v1, parity, surface, help, z, &g);
+	analyze_tetrahedra (&v6, &v2, &v0, &v3, parity, surface, help, z, &g);
+      }
+    }
+}
+
+static void  iso_slice_evaluate_bcl (slice_t * s1, slice_t * s2, slice_t * s3,
+				     GtsCartesianGrid g, 
+				     gint z, GtsSurface * surface, 
+				     helper_bcl * help)
+{
+  gint x,y; 
+  tetra_vertex_t v0, v1, v2, v3, v4, v5, v6, v7, v8, v9, w0; 
+  gdouble ** s1p = s1->data;
+  gdouble ** s2p = s2->data;
+  gdouble ** s3p = s3->data;
+	
+  for (y = 0; y < g.ny-2; y++)
+    for (x = 0; x < g.nx-2; x++) {
+      v0.x = x  ; v0.y = y  ; v0.z = z  ; v0.mid = TRUE;
+      v0.d = (s1p[x  ][y  ] + s2p[x  ][y  ] +
+	      s1p[x  ][y+1] + s2p[x  ][y+1] +
+	      s1p[x+1][y  ] + s2p[x+1][y  ] +
+	      s1p[x+1][y+1] + s2p[x+1][y+1])/8.0;
+
+      v1.x = x+1; v1.y = y  ; v1.z = z  ; v1.mid = TRUE;
+      v1.d = (s1p[x+1][y  ] + s2p[x+1][y  ] +
+	      s1p[x+1][y+1] + s2p[x+1][y+1] +
+	      s1p[x+2][y  ] + s2p[x+2][y  ] +
+	      s1p[x+2][y+1] + s2p[x+2][y+1])/8.0;
+
+      v2.x = x  ; v2.y = y+1; v2.z = z  ; v2.mid = TRUE;
+      v2.d = (s1p[x  ][y+1] + s2p[x  ][y+1] +
+	      s1p[x  ][y+2] + s2p[x  ][y+2] +
+	      s1p[x+1][y+1] + s2p[x+1][y+1] +
+	      s1p[x+1][y+2] + s2p[x+1][y+2])/8.0;
+
+      v3.x = x  ; v3.y = y  ; v3.z = z+1; v3.mid = TRUE;
+      v3.d = (s2p[x  ][y  ] + s3p[x  ][y  ] +
+	      s2p[x  ][y+1] + s3p[x  ][y+1] +
+	      s2p[x+1][y  ] + s3p[x+1][y  ] +
+	      s2p[x+1][y+1] + s3p[x+1][y+1])/8.0;
+
+      v4.x = x+1; v4.y = y  ; v4.z = z  ; v4.mid = FALSE; v4.d = s1p[x+1][y  ];
+      v5.x = x  ; v5.y = y+1; v5.z = z  ; v5.mid = FALSE; v5.d = s1p[x  ][y+1];
+      v6.x = x+1; v6.y = y+1; v6.z = z  ; v6.mid = FALSE; v6.d = s1p[x+1][y+1];
+      v7.x = x+1; v7.y = y  ; v7.z = z+1; v7.mid = FALSE; v7.d = s2p[x+1][y  ];
+      v8.x = x  ; v8.y = y+1; v8.z = z+1; v8.mid = FALSE; v8.d = s2p[x  ][y+1];
+      v9.x = x+1; v9.y = y+1; v9.z = z+1; v9.mid = FALSE; v9.d = s2p[x+1][y+1];
+      w0.x = x  ; w0.y = y  ; w0.z = z+1; w0.mid = FALSE; w0.d = s2p[x  ][y  ];
+
+      analyze_tetrahedra_bcl (&v0, &v9, &v6, &v1, surface, help, z, &g);
+      analyze_tetrahedra_bcl (&v0, &v6, &v4, &v1, surface, help, z, &g);
+      analyze_tetrahedra_bcl (&v0, &v4, &v7, &v1, surface, help, z, &g);
+      analyze_tetrahedra_bcl (&v0, &v7, &v9, &v1, surface, help, z, &g);
+      analyze_tetrahedra_bcl (&v0, &v5, &v6, &v2, surface, help, z, &g);
+      analyze_tetrahedra_bcl (&v0, &v6, &v9, &v2, surface, help, z, &g);
+      analyze_tetrahedra_bcl (&v0, &v9, &v8, &v2, surface, help, z, &g);
+      analyze_tetrahedra_bcl (&v0, &v8, &v5, &v2, surface, help, z, &g);
+      analyze_tetrahedra_bcl (&v0, &v8, &v9, &v3, surface, help, z, &g);
+      analyze_tetrahedra_bcl (&v0, &v9, &v7, &v3, surface, help, z, &g);
+      analyze_tetrahedra_bcl (&v0, &v7, &w0, &v3, surface, help, z, &g);
+      analyze_tetrahedra_bcl (&v0, &w0, &v8, &v3, surface, help, z, &g);
+    }
+}
+
+/*  copy src into dest by stripping off the iso value and leave out
+    the boundary (which should be G_MINDOUBLE) */
+static void copy_to_bounded (slice_t * dest, slice_t * src, 
+			     gdouble iso, gdouble fill)
+{
+  gint x,y; 
+  gdouble * src_ptr;
+  gdouble * dest_ptr = dest->data[0];
+  
+  g_assert(dest->ny == src->ny + 2);
+  g_assert(dest->nx == src->nx + 2);
+	
+  for (y = 0; y < dest->ny; ++y, ++dest_ptr)
+    *dest_ptr = fill; 
+	
+  for (x = 1; x < src->nx - 1; ++x) {
+    dest_ptr = dest->data[x];
+    src_ptr = src->data[x-1];
+    *dest_ptr++ = fill;
+    for (y = 0; y < src->ny; ++y, ++dest_ptr, ++src_ptr)
+      *dest_ptr  = *src_ptr - iso;
+    *dest_ptr++ = fill; 
+  }
+  
+  dest_ptr = dest->data[y];
+  
+  for (y = 0; y < dest->ny; ++y, ++dest_ptr)
+    *dest_ptr = fill; 
+}
+
+static void iso_sub (slice_t * s, gdouble iso)
+{
+  gint x,y; 
+
+  for (x = 0; x < s->nx; ++x) {
+    gdouble *ptr = s->data[x];
+
+    for (y = 0; y < s->ny; ++y, ++ptr)
+      *ptr -= iso; 
+  }
+}
+
+
+/**
+ * gts_isosurface_tetra_bounded:
+ * @surface: a #GtsSurface.
+ * @g: a #GtsCartesianGrid.
+ * @f: a #GtsIsoCartesianFunc.
+ * @data: user data to be passed to @f.
+ * @iso: isosurface value.
+ *
+ * Adds to @surface new faces defining the isosurface f(x,y,z) =
+ * @iso. By convention, the normals to the surface are pointing toward
+ * the positive values of f(x,y,z) - @iso. To ensure a closed object,
+ * a boundary of G_MINDOUBLE is added around the domain
+ *
+ * The user function @f is called successively for each value of the z
+ * coordinate defined by @g. It must fill the corresponding (x,y)
+ * plane with the values of the function for which the isosurface is
+ * to be computed.  
+ */
+void gts_isosurface_tetra_bounded (GtsSurface * surface,
+				   GtsCartesianGrid g,
+				   GtsIsoCartesianFunc f,
+				   gpointer data,
+				   gdouble iso)
+{
+  slice_t *slice1, *slice2, *transfer_slice; 
+  GtsCartesianGrid g_intern = g; 
+  helper_t *helper;
+  gint z; 
+	
+  g_return_if_fail (surface != NULL);
+  g_return_if_fail (f != NULL);
+  g_return_if_fail (g.nx > 1);
+  g_return_if_fail (g.ny > 1);
+  g_return_if_fail (g.nz > 1);
+
+  /* create the helper slices */
+  slice1 = new_slice (g.nx + 2, g.ny + 2);
+  slice2 = new_slice (g.nx + 2, g.ny + 2);
+	
+  /*  initialize the first slice as OUTSIDE */
+  slice_init (slice1, -1.0);
+	
+  /* create a slice of the original image size */
+  transfer_slice = new_slice (g.nx, g.ny);
+	
+  /* adapt the parameters to our enlarged image */
+  g_intern.x -= g.dx;
+  g_intern.y -= g.dy; 
+  g_intern.z -= g.dz;
+  g_intern.nx = g.nx + 2;
+  g_intern.ny = g.ny + 2; 	
+  g_intern.nz = g.nz;
+	
+  /* create the helper for vertex-lookup */
+  helper = init_helper (g_intern.nx, g_intern.ny);
+	
+  /* go slicewise through the data */
+  z = 0; 
+  while (z < g.nz) {
+    slice_t * hs; 
+    
+    /* request slice */
+    f (transfer_slice->data, g, z, data);
+    g.z += g.dz; 
+    
+    /* copy slice in enlarged image and mark the border as OUTSIDE */
+    copy_to_bounded (slice2, transfer_slice, iso, -1.);
+    
+    /* triangulate */
+    iso_slice_evaluate (slice1, slice2, g_intern, z, surface, helper);
+    
+    /* switch the input slices */
+    hs = slice1; slice1 = slice2; slice2 = hs; 
+    
+    /* switch the vertex lookup tables */
+    helper_advance(helper);
+    ++z; 
+  }
+  
+  /* initialize the last slice as OUTSIDE */
+  slice_init (slice2, - 1.0);
+		
+  /* close the object */
+  iso_slice_evaluate(slice1, slice2, g_intern, z, surface, helper);
+  
+  free_helper (helper);
+  free_slice (slice1);
+  free_slice (slice2);
+  free_slice (transfer_slice);	
+}
+
+/**
+ * gts_isosurface_tetra:
+ * @surface: a #GtsSurface.
+ * @g: a #GtsCartesianGrid.
+ * @f: a #GtsIsoCartesianFunc.
+ * @data: user data to be passed to @f.
+ * @iso: isosurface value.
+ *
+ * Adds to @surface new faces defining the isosurface f(x,y,z) =
+ * @iso. By convention, the normals to the surface are pointing toward
+ * the positive values of f(x,y,z) - @iso.
+ *
+ * The user function @f is called successively for each value of the z
+ * coordinate defined by @g. It must fill the corresponding (x,y)
+ * plane with the values of the function for which the isosurface is
+ * to be computed.  
+ */
+void gts_isosurface_tetra (GtsSurface * surface,
+			   GtsCartesianGrid g,
+			   GtsIsoCartesianFunc f,
+			   gpointer data,
+			   gdouble iso)
+{
+  slice_t *slice1, *slice2; 
+  helper_t *helper;
+  gint z; 
+  GtsCartesianGrid g_internal;
+  
+  g_return_if_fail (surface != NULL);
+  g_return_if_fail (f != NULL);
+  g_return_if_fail (g.nx > 1);
+  g_return_if_fail (g.ny > 1);
+  g_return_if_fail (g.nz > 1);
+
+  memcpy (&g_internal, &g, sizeof (GtsCartesianGrid));
+	
+  /* create the helper slices */
+  slice1 = new_slice (g.nx, g.ny);
+  slice2 = new_slice (g.nx, g.ny);
+  
+  /* create the helper for vertex-lookup */
+  helper = init_helper (g.nx, g.ny);
+	
+  z = 0;
+  f (slice1->data, g, z, data);
+  iso_sub (slice1, iso); 
+  
+  z++; 
+  g.z += g.dz;
+  
+  /* go slicewise through the data */
+  while (z < g.nz) {
+    slice_t * hs; 
+    
+    /* request slice */
+    f (slice2->data, g, z, data);
+    iso_sub (slice2, iso);
+     
+    g.z += g.dz;
+    
+    /* triangulate */
+    iso_slice_evaluate (slice1, slice2, g_internal, z-1, surface, helper);
+    
+    /* switch the input slices */
+    hs = slice1; slice1 = slice2; slice2 = hs; 
+    
+    /* switch the vertex lookup tables */
+    helper_advance (helper);
+    
+    ++z; 
+  }
+
+  free_helper(helper);
+  free_slice(slice1);
+  free_slice(slice2);	
+}
+
+/**
+ * gts_isosurface_tetra_bcl:
+ * @surface: a #GtsSurface.
+ * @g: a #GtsCartesianGrid.
+ * @f: a #GtsIsoCartesianFunc.
+ * @data: user data to be passed to @f.
+ * @iso: isosurface value.
+ *
+ * Adds to @surface new faces defining the isosurface f(x,y,z) =
+ * @iso. By convention, the normals to the surface are pointing toward
+ * the positive values of f(x,y,z) - @iso.
+ *
+ * The user function @f is called successively for each value of the z
+ * coordinate defined by @g. It must fill the corresponding (x,y)
+ * plane with the values of the function for which the isosurface is
+ * to be computed.  
+ *
+ * This version produces the dual "body-centered" faces relative to
+ * the faces produced by gts_isosurface_tetra().
+ */
+void gts_isosurface_tetra_bcl (GtsSurface * surface,
+			       GtsCartesianGrid g,
+			       GtsIsoCartesianFunc f,
+			       gpointer data,
+			       gdouble iso)
+{
+  slice_t *slice1, *slice2, *slice3;
+  helper_bcl *helper;
+  gint z; 
+  GtsCartesianGrid g_internal;
+  
+  g_return_if_fail (surface != NULL);
+  g_return_if_fail (f != NULL);
+  g_return_if_fail (g.nx > 1);
+  g_return_if_fail (g.ny > 1);
+  g_return_if_fail (g.nz > 1);
+
+  memcpy (&g_internal, &g, sizeof (GtsCartesianGrid));
+	
+  /* create the helper slices */
+  slice1 = new_slice (g.nx, g.ny);
+  slice2 = new_slice (g.nx, g.ny);
+  slice3 = new_slice (g.nx, g.ny);
+  
+  /* create the helper for vertex-lookup */
+  helper = init_helper_bcl ();
+	
+  z = 0;
+  f (slice1->data, g, z, data);
+  iso_sub (slice1, iso); 
+
+  z++; 
+  g.z += g.dz;
+
+  f (slice2->data, g, z, data);
+  iso_sub (slice1, iso); 
+  
+  z++; 
+  g.z += g.dz;
+  
+  /* go slicewise through the data */
+  while (z < g.nz) {
+    slice_t * hs; 
+    
+    /* request slice */
+    f (slice3->data, g, z, data);
+    iso_sub (slice3, iso);
+     
+    g.z += g.dz;
+    
+    /* triangulate */
+    iso_slice_evaluate_bcl (slice1, slice2, slice3, g_internal, z-2, 
+			    surface, helper);
+    
+    /* switch the input slices */
+    hs = slice1; slice1 = slice2; slice2 = slice3; slice3 = hs;
+    
+    /* switch the vertex lookup tables */
+    helper_advance_bcl (helper);
+    
+    ++z; 
+  }
+
+  free_helper_bcl(helper);
+  free_slice(slice1);
+  free_slice(slice2);	
+  free_slice(slice3);	
+}
diff --git a/gts/kdtree.c b/gts/kdtree.c
new file mode 100644
index 0000000..ec5d422
--- /dev/null
+++ b/gts/kdtree.c
@@ -0,0 +1,152 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <stdlib.h>
+#include "gts.h"
+
+
+static int compare_x (const void * p1, const void * p2) {
+  GtsPoint 
+    * pp1 = *((gpointer *) p1),
+    * pp2 = *((gpointer *) p2);
+  if (pp1->x > pp2->x)
+    return 1;
+  return -1;
+}
+
+static int compare_y (const void * p1, const void * p2) {
+  GtsPoint
+    * pp1 = *((gpointer *) p1),
+    * pp2 = *((gpointer *) p2);
+  if (pp1->y > pp2->y)
+    return 1;
+  return -1;
+}
+
+static int compare_z (const void * p1, const void * p2) {
+  GtsPoint 
+    * pp1 = *((gpointer *) p1),
+    * pp2 = *((gpointer *) p2);
+  if (pp1->z > pp2->z)
+    return 1;
+  return -1;
+}
+
+/**
+ * gts_kdtree_new:
+ * @points: an array of #GtsPoint.
+ * @compare: always %NULL.
+ *
+ * Note that the order of the points in array @points is modified by this
+ * function.
+ * 
+ * Returns: a new 3D tree for @points.
+ */
+GNode * gts_kdtree_new (GPtrArray * points, 
+			int (*compare) (const void *, const void *))
+{
+  guint middle;
+  GPtrArray array;
+  GNode * node;
+  GtsPoint * point;
+
+  g_return_val_if_fail (points != NULL, NULL);
+  g_return_val_if_fail (points->len > 0, NULL);
+
+  /* sort the points */
+  if (compare == compare_x) compare = compare_y;
+  else if (compare == compare_y) compare = compare_z;
+  else compare = compare_x;
+  qsort (points->pdata, points->len, sizeof (gpointer), compare);
+
+  middle = (points->len - 1)/2;
+  point = points->pdata[middle];
+  node = g_node_new (point);
+
+  if (points->len > 1) {
+    array.len = middle;
+    if (array.len > 0) {
+      array.pdata = points->pdata;
+      g_node_prepend (node, gts_kdtree_new (&array, compare));
+    }
+    else
+      g_node_prepend (node, g_node_new (NULL));
+    
+    array.len = points->len - middle - 1;
+    if (array.len > 0) {
+      array.pdata = &(points->pdata[middle + 1]);
+      g_node_prepend (node, gts_kdtree_new (&array, compare));
+    }
+    else
+      g_node_prepend (node, g_node_new (NULL));
+  }
+
+  return node;
+}
+
+/**
+ * gts_kdtree_range:
+ * @tree: a 3D tree.
+ * @bbox: a #GtsBBox.
+ * @compare: always %NULL.
+ *
+ * Returns: a list of #GtsPoint belonging to @tree which are inside @bbox.
+ */
+GSList * gts_kdtree_range (GNode * tree_3d,
+			   GtsBBox * bbox,
+			   int (*compare) (const void *, const void *))
+{
+  GSList * list = NULL;
+  GtsPoint * p;
+  gdouble left, right, v;
+  GNode * node;
+
+  g_return_val_if_fail (tree_3d != NULL, NULL);
+  g_return_val_if_fail (bbox != NULL, NULL);
+
+  p = tree_3d->data;
+  if (p == NULL)
+    return NULL;
+
+  if (gts_bbox_point_is_inside (bbox, p))
+    list = g_slist_prepend (list, p);
+
+  if (compare == compare_x) {
+    left = bbox->y1; right = bbox->y2; v = p->y;
+    compare = compare_y;
+  }
+  else if (compare == compare_y) {
+    left = bbox->z1; right = bbox->z2; v = p->z;
+    compare = compare_z;
+  }
+  else {
+    left = bbox->x1; right = bbox->x2; v = p->x;
+    compare = compare_x;
+  }
+
+  if ((node = tree_3d->children)) {
+    if (right >= v)
+      list = g_slist_concat (list, gts_kdtree_range (node, bbox, compare));
+    node = node->next;
+    if (left <= v)
+      list = g_slist_concat (list, gts_kdtree_range (node, bbox, compare));
+  }
+  return list;
+}
+
diff --git a/gts/matrix.c b/gts/matrix.c
new file mode 100644
index 0000000..7ada15d
--- /dev/null
+++ b/gts/matrix.c
@@ -0,0 +1,725 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <math.h>
+#include "gts.h"
+
+/**
+ * gts_matrix_new:
+ * @a00: element [0][0].
+ * @a01: element [0][1].
+ * @a02: element [0][2].
+ * @a03: element [0][3].
+ * @a10: element [1][0].
+ * @a11: element [1][1].
+ * @a12: element [1][2].
+ * @a13: element [1][3].
+ * @a20: element [2][0].
+ * @a21: element [2][1].
+ * @a22: element [2][2].
+ * @a23: element [2][3].
+ * @a30: element [3][0].
+ * @a31: element [3][1].
+ * @a32: element [3][2].
+ * @a33: element [3][3].
+ *
+ * Allocates memory and initializes a new #GtsMatrix.
+ *
+ * Returns: a pointer to the newly created #GtsMatrix.
+ */
+GtsMatrix * gts_matrix_new (gdouble a00, gdouble a01, gdouble a02, gdouble a03,
+			    gdouble a10, gdouble a11, gdouble a12, gdouble a13,
+			    gdouble a20, gdouble a21, gdouble a22, gdouble a23,
+			    gdouble a30, gdouble a31, gdouble a32, gdouble a33)
+{
+  GtsMatrix * m;
+
+  m = g_malloc (4*sizeof (GtsVector4));
+
+  m[0][0] = a00; m[1][0] = a10; m[2][0] = a20; m[3][0] = a30;
+  m[0][1] = a01; m[1][1] = a11; m[2][1] = a21; m[3][1] = a31;
+  m[0][2] = a02; m[1][2] = a12; m[2][2] = a22; m[3][2] = a32;
+  m[0][3] = a03; m[1][3] = a13; m[2][3] = a23; m[3][3] = a33;
+
+  return m;
+}
+
+/**
+ * gts_matrix_assign:
+ * @m: a #GtsMatrix.
+ * @a00: element [0][0].
+ * @a01: element [0][1].
+ * @a02: element [0][2].
+ * @a03: element [0][3].
+ * @a10: element [1][0].
+ * @a11: element [1][1].
+ * @a12: element [1][2].
+ * @a13: element [1][3].
+ * @a20: element [2][0].
+ * @a21: element [2][1].
+ * @a22: element [2][2].
+ * @a23: element [2][3].
+ * @a30: element [3][0].
+ * @a31: element [3][1].
+ * @a32: element [3][2].
+ * @a33: element [3][3].
+ *
+ * Set values of matrix elements.
+ */
+void gts_matrix_assign (GtsMatrix * m,
+			gdouble a00, gdouble a01, gdouble a02, gdouble a03,
+			gdouble a10, gdouble a11, gdouble a12, gdouble a13,
+			gdouble a20, gdouble a21, gdouble a22, gdouble a23,
+			gdouble a30, gdouble a31, gdouble a32, gdouble a33)
+{
+  g_return_if_fail (m != NULL);
+
+  m[0][0] = a00; m[1][0] = a10; m[2][0] = a20; m[3][0] = a30;
+  m[0][1] = a01; m[1][1] = a11; m[2][1] = a21; m[3][1] = a31;
+  m[0][2] = a02; m[1][2] = a12; m[2][2] = a22; m[3][2] = a32;
+  m[0][3] = a03; m[1][3] = a13; m[2][3] = a23; m[3][3] = a33;
+}
+
+/**
+ * gts_matrix_projection:
+ * @t: a #GtsTriangle.
+ *
+ * Creates a new #GtsMatrix representing the projection onto a plane of normal
+ * given by @t.
+ *
+ * Returns: a pointer to the newly created #GtsMatrix.
+ */
+GtsMatrix * gts_matrix_projection (GtsTriangle * t)
+{
+  GtsVertex * v1, * v2, * v3;
+  GtsEdge * e1, * e2, * e3;
+  GtsMatrix * m;
+  gdouble x1, y1, z1, x2, y2, z2, x3, y3, z3, l;
+  
+  g_return_val_if_fail (t != NULL, NULL);
+
+  m = g_malloc (4*sizeof (GtsVector4));
+  gts_triangle_vertices_edges (t, NULL, &v1, &v2, &v3, &e1, &e2, &e3);
+
+  x1 = GTS_POINT (v2)->x - GTS_POINT (v1)->x; 
+  y1 = GTS_POINT (v2)->y - GTS_POINT (v1)->y; 
+  z1 = GTS_POINT (v2)->z - GTS_POINT (v1)->z;
+  x2 = GTS_POINT (v3)->x - GTS_POINT (v1)->x; 
+  y2 = GTS_POINT (v3)->y - GTS_POINT (v1)->y; 
+  z2 = GTS_POINT (v3)->z - GTS_POINT (v1)->z;
+  x3 = y1*z2 - z1*y2; y3 = z1*x2 - x1*z2; z3 = x1*y2 - y1*x2;
+  x2 = y3*z1 - z3*y1; y2 = z3*x1 - x3*z1; z2 = x3*y1 - y3*x1;
+
+  g_assert ((l = sqrt (x1*x1 + y1*y1 + z1*z1)) > 0.0);
+  m[0][0] = x1/l; m[1][0] = y1/l; m[2][0] = z1/l; m[3][0] = 0.;
+  g_assert ((l = sqrt (x2*x2 + y2*y2 + z2*z2)) > 0.0);
+  m[0][1] = x2/l; m[1][1] = y2/l; m[2][1] = z2/l; m[3][1] = 0.;
+  g_assert ((l = sqrt (x3*x3 + y3*y3 + z3*z3)) > 0.0);
+  m[0][2] = x3/l; m[1][2] = y3/l; m[2][2] = z3/l; m[3][2] = 0.;
+  m[0][3] = 0; m[1][3] = 0.; m[2][3] = 0.; m[3][3] = 1.;
+
+  return m;
+}
+
+/**
+ * gts_matrix_transpose:
+ * @m: a #GtsMatrix.
+ *
+ * Returns: a pointer to a newly created #GtsMatrix transposed of @m.
+ */
+GtsMatrix * gts_matrix_transpose (GtsMatrix * m)
+{
+  GtsMatrix * mi;
+
+  g_return_val_if_fail (m != NULL, NULL);
+
+  mi = g_malloc (4*sizeof (GtsVector4));
+
+  mi[0][0] = m[0][0]; mi[1][0] = m[0][1]; 
+  mi[2][0] = m[0][2]; mi[3][0] = m[0][3];
+  mi[0][1] = m[1][0]; mi[1][1] = m[1][1]; 
+  mi[2][1] = m[1][2]; mi[3][1] = m[1][3];
+  mi[0][2] = m[2][0]; mi[1][2] = m[2][1]; 
+  mi[2][2] = m[2][2]; mi[3][2] = m[2][3];
+  mi[0][3] = m[3][0]; mi[1][3] = m[3][1]; 
+  mi[2][3] = m[3][2]; mi[3][3] = m[3][3];
+
+  return mi;
+}
+
+/*
+ * calculate the determinant of a 2x2 matrix.
+ * 
+ * Adapted from:
+ * Matrix Inversion
+ * by Richard Carling
+ * from "Graphics Gems", Academic Press, 1990
+ */
+static gdouble det2x2 (gdouble a, gdouble b, gdouble c, gdouble d)
+{
+  gdouble ans2;
+
+  ans2 = a*d - b*c;
+  return ans2;
+}
+
+/*
+ * calculate the determinant of a 3x3 matrix
+ * in the form
+ *
+ *     | a1,  b1,  c1 |
+ *     | a2,  b2,  c2 |
+ *     | a3,  b3,  c3 |
+ *
+ * Adapted from:
+ * Matrix Inversion
+ * by Richard Carling
+ * from "Graphics Gems", Academic Press, 1990
+ */
+static gdouble det3x3 (gdouble a1, gdouble a2, gdouble a3, 
+		       gdouble b1, gdouble b2, gdouble b3, 
+		       gdouble c1, gdouble c2, gdouble c3)
+{
+  gdouble ans3;
+
+  ans3 = a1 * det2x2( b2, b3, c2, c3 )
+    - b1 * det2x2( a2, a3, c2, c3 )
+    + c1 * det2x2( a2, a3, b2, b3 );
+  return ans3;
+}
+
+/**
+ * gts_matrix_determinant:
+ * @m: a #GtsMatrix.
+ *
+ * Returns: the value of det(@m).
+ */
+gdouble gts_matrix_determinant (GtsMatrix * m)
+{
+  gdouble ans4;
+  gdouble a1, a2, a3, a4, b1, b2, b3, b4, c1, c2, c3, c4, d1, d2, d3, d4;
+
+  g_return_val_if_fail (m != NULL, 0.0);
+
+  a1 = m[0][0]; b1 = m[0][1]; 
+  c1 = m[0][2]; d1 = m[0][3];
+  
+  a2 = m[1][0]; b2 = m[1][1]; 
+  c2 = m[1][2]; d2 = m[1][3];
+  
+  a3 = m[2][0]; b3 = m[2][1]; 
+  c3 = m[2][2]; d3 = m[2][3];
+  
+  a4 = m[3][0]; b4 = m[3][1]; 
+  c4 = m[3][2]; d4 = m[3][3];
+  
+  ans4 = a1 * det3x3 (b2, b3, b4, c2, c3, c4, d2, d3, d4)
+    - b1 * det3x3 (a2, a3, a4, c2, c3, c4, d2, d3, d4)
+    + c1 * det3x3 (a2, a3, a4, b2, b3, b4, d2, d3, d4)
+    - d1 * det3x3 (a2, a3, a4, b2, b3, b4, c2, c3, c4);
+
+  return ans4;
+}
+
+/* 
+ *   adjoint( original_matrix, inverse_matrix )
+ * 
+ *     calculate the adjoint of a 4x4 matrix
+ *
+ *      Let  a   denote the minor determinant of matrix A obtained by
+ *           ij
+ *
+ *      deleting the ith row and jth column from A.
+ *
+ *                    i+j
+ *     Let  b   = (-1)    a
+ *          ij            ji
+ *
+ *    The matrix B = (b  ) is the adjoint of A
+ *                     ij
+ */
+static GtsMatrix * adjoint (GtsMatrix * m)
+{
+  gdouble a1, a2, a3, a4, b1, b2, b3, b4;
+  gdouble c1, c2, c3, c4, d1, d2, d3, d4;
+  GtsMatrix * ma;
+
+  a1 = m[0][0]; b1 = m[0][1]; 
+  c1 = m[0][2]; d1 = m[0][3];
+  
+  a2 = m[1][0]; b2 = m[1][1]; 
+  c2 = m[1][2]; d2 = m[1][3];
+  
+  a3 = m[2][0]; b3 = m[2][1];
+  c3 = m[2][2]; d3 = m[2][3];
+  
+  a4 = m[3][0]; b4 = m[3][1]; 
+  c4 = m[3][2]; d4 = m[3][3];
+
+  ma = g_malloc (4*sizeof (GtsVector4));
+
+  /* row column labeling reversed since we transpose rows & columns */
+
+  ma[0][0]  =   det3x3 (b2, b3, b4, c2, c3, c4, d2, d3, d4);
+  ma[1][0]  = - det3x3 (a2, a3, a4, c2, c3, c4, d2, d3, d4);
+  ma[2][0]  =   det3x3 (a2, a3, a4, b2, b3, b4, d2, d3, d4);
+  ma[3][0]  = - det3x3 (a2, a3, a4, b2, b3, b4, c2, c3, c4);
+  
+  ma[0][1]  = - det3x3 (b1, b3, b4, c1, c3, c4, d1, d3, d4);
+  ma[1][1]  =   det3x3 (a1, a3, a4, c1, c3, c4, d1, d3, d4);
+  ma[2][1]  = - det3x3 (a1, a3, a4, b1, b3, b4, d1, d3, d4);
+  ma[3][1]  =   det3x3 (a1, a3, a4, b1, b3, b4, c1, c3, c4);
+  
+  ma[0][2]  =   det3x3 (b1, b2, b4, c1, c2, c4, d1, d2, d4);
+  ma[1][2]  = - det3x3 (a1, a2, a4, c1, c2, c4, d1, d2, d4);
+  ma[2][2]  =   det3x3 (a1, a2, a4, b1, b2, b4, d1, d2, d4);
+  ma[3][2]  = - det3x3 (a1, a2, a4, b1, b2, b4, c1, c2, c4);
+  
+  ma[0][3]  = - det3x3 (b1, b2, b3, c1, c2, c3, d1, d2, d3);
+  ma[1][3]  =   det3x3 (a1, a2, a3, c1, c2, c3, d1, d2, d3);
+  ma[2][3]  = - det3x3 (a1, a2, a3, b1, b2, b3, d1, d2, d3);
+  ma[3][3]  =   det3x3 (a1, a2, a3, b1, b2, b3, c1, c2, c3);
+  
+  return ma;
+}
+
+
+/**
+ * gts_matrix_inverse:
+ * @m: a #GtsMatrix.
+ *
+ * Returns: a pointer to a newly created #GtsMatrix inverse of @m or %NULL
+ * if @m is not invertible.
+ */
+GtsMatrix * gts_matrix_inverse (GtsMatrix * m)
+{
+  GtsMatrix * madj;
+  gdouble det;
+  gint i, j;
+
+  g_return_val_if_fail (m != NULL, NULL);
+  
+  det = gts_matrix_determinant (m);
+  if (det == 0.)
+    return NULL;
+
+  madj = adjoint (m);
+  for (i = 0; i < 4; i++)
+    for(j = 0; j < 4; j++)
+      madj[i][j] /= det;
+
+  return madj;
+}
+
+/**
+ * gts_matrix3_inverse:
+ * @m: a 3x3 #GtsMatrix.
+ *
+ * Returns: a pointer to a newly created 3x3 #GtsMatrix inverse of @m or %NULL
+ * if @m is not invertible.
+ */
+GtsMatrix * gts_matrix3_inverse (GtsMatrix * m)
+{
+  GtsMatrix * mi;
+  gdouble det;
+
+  g_return_val_if_fail (m != NULL, NULL);
+  
+  det = (m[0][0]*(m[1][1]*m[2][2] - m[2][1]*m[1][2]) - 
+	 m[0][1]*(m[1][0]*m[2][2] - m[2][0]*m[1][2]) + 
+	 m[0][2]*(m[1][0]*m[2][1] - m[2][0]*m[1][1]));
+  if (det == 0.0)
+    return NULL;
+
+  mi = g_malloc0 (4*sizeof (GtsVector));
+
+  mi[0][0] = (m[1][1]*m[2][2] - m[1][2]*m[2][1])/det; 
+  mi[0][1] = (m[2][1]*m[0][2] - m[0][1]*m[2][2])/det;
+  mi[0][2] = (m[0][1]*m[1][2] - m[1][1]*m[0][2])/det; 
+  mi[1][0] = (m[1][2]*m[2][0] - m[1][0]*m[2][2])/det; 
+  mi[1][1] = (m[0][0]*m[2][2] - m[2][0]*m[0][2])/det; 
+  mi[1][2] = (m[1][0]*m[0][2] - m[0][0]*m[1][2])/det; 
+  mi[2][0] = (m[1][0]*m[2][1] - m[2][0]*m[1][1])/det; 
+  mi[2][1] = (m[2][0]*m[0][1] - m[0][0]*m[2][1])/det; 
+  mi[2][2] = (m[0][0]*m[1][1] - m[0][1]*m[1][0])/det; 
+
+  return mi;
+}
+
+/**
+ * gts_matrix_print:
+ * @m: a #GtsMatrix.
+ * @fptr: a file descriptor.
+ * 
+ * Print @m to file @fptr.
+ */
+void gts_matrix_print (GtsMatrix * m, FILE * fptr)
+{
+  g_return_if_fail (m != NULL);
+  g_return_if_fail (fptr != NULL);
+
+  fprintf (fptr, 
+	   "[[%15.7g %15.7g %15.7g %15.7g]\n"
+	   " [%15.7g %15.7g %15.7g %15.7g]\n"
+	   " [%15.7g %15.7g %15.7g %15.7g]\n"
+	   " [%15.7g %15.7g %15.7g %15.7g]]\n",
+	   m[0][0], m[0][1], m[0][2], m[0][3],
+	   m[1][0], m[1][1], m[1][2], m[1][3],
+	   m[2][0], m[2][1], m[2][2], m[2][3],
+	   m[3][0], m[3][1], m[3][2], m[3][3]);
+}
+
+/**
+ * gts_vector_print:
+ * @v: a #GtsVector.
+ * @fptr: a file descriptor.
+ * 
+ * Print @s to file @fptr.
+ */
+void gts_vector_print (GtsVector v, FILE * fptr)
+{
+  g_return_if_fail (fptr != NULL);
+
+  fprintf (fptr, 
+	   "[%15.7g %15.7g %15.7g ]\n",
+	   v[0], v[1], v[2]);
+}
+
+/**
+ * gts_vector4_print:
+ * @v: a #GtsVector4.
+ * @fptr: a file descriptor.
+ * 
+ * Print @v to file @fptr.
+ */
+void gts_vector4_print (GtsVector4 v, FILE * fptr)
+{
+  g_return_if_fail (fptr != NULL);
+
+  fprintf (fptr, 
+	   "[%15.7g %15.7g %15.7g %15.7g]\n",
+	   v[0], v[1], v[2], v[3]);
+}
+
+/* [cos(alpha)]^2 */
+#define COSALPHA2 0.999695413509 /* alpha = 1 degree */
+/* [sin(alpha)]^2 */
+#define SINALPHA2 3.04586490453e-4 /* alpha = 1 degree */
+
+/**
+ * gts_matrix_compatible_row:
+ * @A: a #GtsMatrix.
+ * @b: a #GtsVector.
+ * @n: the number of previous constraints of @A.x=@b.
+ * @A1: a #GtsMatrix.
+ * @b1: a #GtsVector.
+ *
+ * Given a system of @n constraints @A.x=@b adds to it the compatible
+ * constraints defined by @A1.x=@b1. The compatibility is determined
+ * by insuring that the resulting system is well-conditioned (see
+ * Lindstrom and Turk (1998, 1999)).
+ *
+ * Returns: the number of constraints of the resulting system.  
+ */
+guint gts_matrix_compatible_row (GtsMatrix * A,
+				 GtsVector b,
+				 guint n,
+				 GtsVector A1,
+				 gdouble b1)
+{
+  gdouble na1;
+  
+  g_return_val_if_fail (A != NULL, 0);
+
+  na1 = gts_vector_scalar (A1, A1);
+  if (na1 == 0.0)
+    return n;
+
+  /* normalize row */
+  na1 = sqrt (na1);
+  A1[0] /= na1; A1[1] /= na1; A1[2] /= na1; b1 /= na1;
+
+  if (n == 1) {
+    gdouble a0a1 = gts_vector_scalar (A[0], A1);
+    if (a0a1*a0a1 >= COSALPHA2)
+      return 1;
+  }
+  else if (n == 2) {
+    GtsVector V;
+    gdouble s;
+    
+    gts_vector_cross (V, A[0], A[1]);
+    s = gts_vector_scalar (V, A1);
+    if (s*s <= gts_vector_scalar (V, V)*SINALPHA2)
+      return 2;
+  }
+
+  A[n][0] = A1[0]; A[n][1] = A1[1]; A[n][2] = A1[2]; b[n] = b1;
+  return n + 1;
+}
+
+/**
+ * gts_matrix_quadratic_optimization:
+ * @A: a #GtsMatrix.
+ * @b: a #GtsVector.
+ * @n: the number of constraints (must be smaller than 3).
+ * @H: a symmetric positive definite Hessian.
+ * @c: a #GtsVector.
+ *
+ * Solve a quadratic optimization problem: Given a quadratic objective function
+ * f which can be written as: f(x) = x^t.@xxx + @c^t.x + k, where @H is the 
+ * symmetric positive definite Hessian of f and k is a constant, find the
+ * minimum of f subject to the set of @n prior linear constraints, defined by
+ * the first @n rows of @A and @b (@A.x = @b). The new constraints given by
+ * the minimization are added to @A and @b only if they are linearly
+ * independent as determined by gts_matrix_compatible_row().
+ *
+ * Returns: the new number of constraints defined by @A and @b.
+ */
+guint gts_matrix_quadratic_optimization (GtsMatrix * A,
+					 GtsVector b,
+					 guint n,
+					 GtsMatrix * H,
+					 GtsVector c)
+{
+  g_return_val_if_fail (A != NULL, 0);
+  g_return_val_if_fail (b != NULL, 0);
+  g_return_val_if_fail (n < 3, 0);
+  g_return_val_if_fail (H != NULL, 0);
+
+  switch (n) {
+  case 0: {
+    n = gts_matrix_compatible_row (A, b, n, H[0], - c[0]);
+    n = gts_matrix_compatible_row (A, b, n, H[1], - c[1]);
+    n = gts_matrix_compatible_row (A, b, n, H[2], - c[2]);
+    return n;
+  }
+  case 1: {
+    GtsVector Q0 = {0., 0., 0.};
+    GtsVector Q1 = {0., 0., 0.};
+    GtsVector A1;
+    gdouble max = A[0][0]*A[0][0];
+    guint d = 0;
+
+    /* build a vector orthogonal to the constraint */
+    if (A[0][1]*A[0][1] > max) { max = A[0][1]*A[0][1]; d = 1; }
+    if (A[0][2]*A[0][2] > max) { max = A[0][2]*A[0][2]; d = 2; }
+    switch (d) {
+    case 0: Q0[0] = - A[0][2]/A[0][0]; Q0[2] = 1.0; break;
+    case 1: Q0[1] = - A[0][2]/A[0][1]; Q0[2] = 1.0; break;
+    case 2: Q0[2] = - A[0][0]/A[0][2]; Q0[0] = 1.0; break;
+    }
+
+    /* build a second vector orthogonal to the first and to the constraint */
+    gts_vector_cross (Q1, A[0], Q0);
+
+    A1[0] = gts_vector_scalar (Q0, H[0]);
+    A1[1] = gts_vector_scalar (Q0, H[1]);
+    A1[2] = gts_vector_scalar (Q0, H[2]);
+
+    n = gts_matrix_compatible_row (A, b, n, A1, - gts_vector_scalar (Q0, c));
+    
+    A1[0] = gts_vector_scalar (Q1, H[0]);
+    A1[1] = gts_vector_scalar (Q1, H[1]);
+    A1[2] = gts_vector_scalar (Q1, H[2]);
+
+    n = gts_matrix_compatible_row (A, b, n, A1, - gts_vector_scalar (Q1, c));
+
+    return n;
+  }
+  case 2: {
+    /* build a vector orthogonal to the two constraints */
+    GtsVector A1, Q;
+
+    gts_vector_cross (Q, A[0], A[1]);
+    A1[0] = gts_vector_scalar (Q, H[0]);
+    A1[1] = gts_vector_scalar (Q, H[1]);
+    A1[2] = gts_vector_scalar (Q, H[2]);
+    
+    n = gts_matrix_compatible_row (A, b, n, A1, - gts_vector_scalar (Q, c));
+
+    return n;
+  }
+  default:
+    g_assert_not_reached ();
+  }
+  return 0;
+}
+
+/**
+ * gts_matrix_destroy:
+ * @m: a #GtsMatrix.
+ *
+ * Free all the memory allocated for @m.
+ */
+void gts_matrix_destroy (GtsMatrix * m)
+{
+  g_free (m);
+}
+
+/**
+ * gts_matrix_product:
+ * @m1: a #GtsMatrix.
+ * @m2: another #GtsMatrix.
+ *
+ * Returns: a new #GtsMatrix, product of @m1 and @m2.
+ */
+GtsMatrix * gts_matrix_product (GtsMatrix * m1, GtsMatrix * m2)
+{
+  guint i, j;
+  GtsMatrix * m;
+
+  g_return_val_if_fail (m1 != NULL, NULL);
+  g_return_val_if_fail (m2 != NULL, NULL);
+  g_return_val_if_fail (m1 != m2, NULL);
+
+  m = g_malloc (4*sizeof (GtsVector4));
+
+  for (i = 0; i < 4; i++)
+    for (j = 0; j < 4; j++)
+      m[i][j] = m1[i][0]*m2[0][j] + m1[i][1]*m2[1][j] +
+        m1[i][2]*m2[2][j] + m1[i][3]*m2[3][j];
+  return m;
+}
+
+/**
+ * gts_matrix_zero:
+ * @m: a #GtsMatrix or $NULL.
+ *
+ * Initializes @m to zeros. Allocates a matrix if @m is %NULL.
+ *
+ * Returns: the zero'ed matrix.
+ */
+GtsMatrix * gts_matrix_zero (GtsMatrix * m)
+{
+  if (m == NULL)
+    m = g_malloc0 (4*sizeof (GtsVector4));
+  else {
+    m[0][0] = m[1][0] = m[2][0] = m[3][0] = 0.;
+    m[0][1] = m[1][1] = m[2][1] = m[3][1] = 0.;
+    m[0][2] = m[1][2] = m[2][2] = m[3][2] = 0.;
+    m[0][3] = m[1][3] = m[2][3] = m[3][3] = 0.;
+  }
+  return m;
+}
+
+/**
+ * gts_matrix_identity:
+ * @m: a #GtsMatrix or %NULL.
+ *
+ * Initializes @m to an identity matrix. Allocates a matrix if @m is %NULL.
+ *
+ * Returns: the identity matrix.
+ */
+GtsMatrix * gts_matrix_identity (GtsMatrix * m)
+{
+  m = gts_matrix_zero (m);
+  m[0][0] = m[1][1] = m[2][2] = m[3][3] = 1.;
+  return m;
+}
+
+/**
+ * gts_matrix_scale:
+ * @m: a #GtsMatrix or %NULL.
+ * @s: the scaling vector.
+ *
+ * Initializes @m to a scaling matrix for @s. Allocates a matrix if @m
+ * is %NULL.
+ *
+ * Returns: the scaling matrix.
+ */
+GtsMatrix * gts_matrix_scale (GtsMatrix * m, GtsVector s)
+{
+  m = gts_matrix_zero (m);
+  m[0][0] = s[0];
+  m[1][1] = s[1];
+  m[2][2] = s[2];
+  m[3][3] = 1.;
+  return m;
+}
+
+/**
+ * gts_matrix_translate:
+ * @m: a #GtsMatrix or %NULL.
+ * @t: the translation vector.
+ *
+ * Initializes @m to a translation matrix for @t.  Allocates a new
+ * matrix if @m is %NULL.
+ *
+ * Returns: the translation matix.
+ */
+GtsMatrix * gts_matrix_translate (GtsMatrix * m, GtsVector t)
+{
+  m = gts_matrix_zero (m);
+  m[0][3] = t[0];
+  m[1][3] = t[1];
+  m[2][3] = t[2];
+  m[3][3] = 1.;
+  m[0][0] = m[1][1] = m[2][2] = 1.;
+  return m;
+}
+
+/**
+ * gts_matrix_rotate:
+ * @m: a #GtsMatrix or %NULL.
+ * @r: the rotation axis.
+ * @angle: the angle (in radians) to rotate by.
+ *
+ * Initializes @m to a rotation matrix around @r by @angle.
+ * Allocates a new matrix if @m is %NULL.
+ *
+ * Returns: the rotation matrix.
+ */
+GtsMatrix * gts_matrix_rotate (GtsMatrix * m,
+			       GtsVector r,
+			       gdouble angle)
+{
+  gdouble c, c1, s;
+
+  gts_vector_normalize (r);
+
+  c = cos (angle);
+  c1 = 1. - c;
+  s = sin (angle);
+
+  if (m == NULL)
+    m = g_malloc (4*sizeof (GtsVector4));
+
+  m[0][0] = r[0]*r[0]*c1 + c;
+  m[0][1] = r[0]*r[1]*c1 - r[2]*s;
+  m[0][2] = r[0]*r[2]*c1 + r[1]*s;
+  m[0][3] = 0.;
+
+  m[1][0] = r[1]*r[0]*c1 + r[2]*s;
+  m[1][1] = r[1]*r[1]*c1 + c;
+  m[1][2] = r[1]*r[2]*c1 - r[0]*s;
+  m[1][3] = 0.;
+
+  m[2][0] = r[2]*r[0]*c1 - r[1]*s;
+  m[2][1] = r[2]*r[1]*c1 + r[0]*s;
+  m[2][2] = r[2]*r[2]*c1 + c;
+  m[2][3] = 0.;
+
+  m[3][0] = 0.;
+  m[3][1] = 0.;
+  m[3][2] = 0.;
+  m[3][3] = 1.;
+
+  return m;
+}
diff --git a/gts/misc.c b/gts/misc.c
new file mode 100644
index 0000000..393ba06
--- /dev/null
+++ b/gts/misc.c
@@ -0,0 +1,692 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "gts.h"
+#include "gts-private.h"
+#include "config.h"
+
+const guint gts_major_version = GTS_MAJOR_VERSION;
+const guint gts_minor_version = GTS_MINOR_VERSION;
+const guint gts_micro_version = GTS_MICRO_VERSION;
+const guint gts_interface_age = 1;
+const guint gts_binary_age = 1;
+
+static gboolean char_in_string (char c, const char * s)
+{
+  while (*s != '\0')
+    if (*(s++) == c)
+      return TRUE;
+  return FALSE;
+}
+
+static GtsFile * file_new (void)
+{
+  GtsFile * f;
+
+  f = g_malloc (sizeof (GtsFile));
+  f->fp = NULL;
+  f->s = f->s1 = NULL;
+  f->curline = 1;
+  f->curpos = 1;
+  f->token = g_string_new ("");
+  f->type = '\0';
+  f->error = NULL;
+  f->next_token = '\0';
+
+  f->scope = f->scope_max = 0;
+  f->delimiters = g_strdup (" \t");
+  f->comments = g_strdup (GTS_COMMENTS);
+  f->tokens = g_strdup ("\n{}()=");
+
+  return f;
+}
+
+/**
+ * gts_file_new:
+ * @fp: a file pointer.
+ *
+ * Returns: a new #GtsFile.
+ */
+GtsFile * gts_file_new (FILE * fp)
+{
+  GtsFile * f;
+
+  g_return_val_if_fail (fp != NULL, NULL);
+
+  f = file_new ();
+  f->fp = fp;
+  gts_file_next_token (f);
+
+  return f;
+}
+
+/**
+ * gts_file_new_from_string:
+ * @s: a string.
+ *
+ * Returns: a new #GtsFile.
+ */
+GtsFile * gts_file_new_from_string (const gchar * s)
+{
+  GtsFile * f;
+
+  g_return_val_if_fail (s != NULL, NULL);
+
+  f = file_new ();
+  f->s1 = f->s = g_strdup (s);
+  gts_file_next_token (f);
+
+  return f;
+}
+
+/**
+ * gts_file_destroy:
+ * @f: a #GtsFile.
+ *
+ * Frees all the memory allocated for @f.
+ */
+void gts_file_destroy (GtsFile * f)
+{
+  g_return_if_fail (f != NULL);
+
+  g_free (f->delimiters);
+  g_free (f->comments);
+  g_free (f->tokens);
+  if (f->error)
+    g_free (f->error);
+  if (f->s1)
+    g_free (f->s1);
+  g_string_free (f->token, TRUE);
+  g_free (f);
+}
+
+/**
+ * gts_file_verror:
+ * @f: a @GtsFile.
+ * @format: the standard sprintf() format string.
+ * @args: the list of parameters to insert into the format string.
+ *
+ * Sets the @error field of @f using g_strdup_vprintf().
+ *
+ * This function can be called only once and disables any other
+ * operation on @f (gts_file_close() excepted).
+ */
+void gts_file_verror (GtsFile * f,
+		      const gchar * format,
+		      va_list args)
+{
+  g_return_if_fail (f != NULL);
+  g_return_if_fail (format != NULL);
+
+  g_assert (f->type != GTS_ERROR);
+  f->error = g_strdup_vprintf (format, args);
+  f->type = GTS_ERROR;
+}
+
+/**
+ * gts_file_error:
+ * @f: a @GtsFile.
+ * @format: the standard sprintf() format string.
+ * @...: the parameters to insert into the format string.
+ *
+ * Sets the @error field of @f using gts_file_verror().
+ *
+ * This function can be called only once and disables any other
+ * operation on @f (gts_file_close() excepted).
+ */
+void gts_file_error (GtsFile * f,
+		     const gchar * format,
+		     ...)
+{
+  va_list args;
+
+  g_return_if_fail (f != NULL);
+  g_return_if_fail (format != NULL);
+
+  va_start (args, format);  
+  gts_file_verror (f, format, args);
+  va_end (args);
+}
+
+static gint next_char (GtsFile * f)
+{
+  if (f->fp)
+    return fgetc (f->fp);
+  else if (*f->s == '\0')
+    return EOF;
+  return *(f->s++);
+}
+
+/**
+ * gts_file_getc :
+ * @f: a #GtsFile.
+ *
+ * Returns: the next character in @f or EOF if the end of the file is
+ * reached or if an error occured.
+ */
+gint gts_file_getc (GtsFile * f)
+{
+  gint c;
+
+  g_return_val_if_fail (f != NULL, EOF);
+
+  if (f->type == GTS_ERROR)
+    return EOF;
+
+  c = next_char (f);
+  f->curpos++;
+  while (char_in_string (c, f->comments)) {
+    while (c != EOF && c != '\n')
+      c = next_char (f);
+    if (c == '\n') {
+      f->curline++;
+      f->curpos = 1;
+      c = next_char (f);
+    }
+  }
+  switch (c) {
+  case '\n': 
+    f->curline++;
+    f->curpos = 1; 
+    break;
+  case '{':
+    f->scope++; 
+    break;
+  case '}':
+    if (f->scope == 0) {
+      f->line = f->curline;
+      f->pos = f->curpos - 1;
+      gts_file_error (f, "no matching opening brace");
+      c = EOF;
+    }
+    else
+      f->scope--;
+  }
+  return c;
+}
+
+/**
+ * gts_file_read:
+ * @f: a #GtsFile.
+ * @ptr: a pointer.
+ * @size: size of an element.
+ * @nmemb: number of elements.
+ *
+ * Reads @nmemb elements of data, each @size bytes long, from @f,
+ * storing them at the location given by @ptr.
+ *
+ * Returns: the number of elements read.
+ */
+guint gts_file_read (GtsFile * f, gpointer ptr, guint size, guint nmemb)
+{
+  guint i, n;
+  gchar * p;
+
+  g_return_val_if_fail (f != NULL, 0);
+  g_return_val_if_fail (ptr != NULL, 0);
+  g_return_val_if_fail (f->fp != NULL, 0);
+
+  if (f->type == GTS_ERROR)
+    return 0;
+
+  n = fread (ptr, size, nmemb, f->fp);
+  for (i = 0, p = ptr; i < n*size; i++, p++) {
+    f->curpos++;
+    if (*p == '\n') {
+      f->curline++;
+      f->curpos = 1;
+    }
+  }
+  return n;
+}
+
+/**
+ * gts_file_getc_scope :
+ * @f: a #GtsFile.
+ *
+ * Returns: the next character in @f in the scope defined by
+ * @f->scope_max or EOF if the end of the file is reached or if an
+ * error occured.
+ */
+gint gts_file_getc_scope (GtsFile * f)
+{
+  gint c;
+
+  g_return_val_if_fail (f != NULL, EOF);
+
+  if (f->type == GTS_ERROR)
+    return EOF;
+  
+  if (f->scope <= f->scope_max)
+    c = gts_file_getc (f);
+  else {
+    c = gts_file_getc (f);
+    while (c != EOF && f->scope > f->scope_max)
+      c = gts_file_getc (f);    
+  }
+  return c;
+}
+
+/**
+ * gts_file_next_token:
+ * @f: a #GtsFile.
+ *
+ * Reads next token from @f and updates its @token and @delim fields.
+ */
+void gts_file_next_token (GtsFile * f)
+{
+  gint c;
+  gboolean in_string = FALSE;
+
+  g_return_if_fail (f != NULL);
+
+  if (f->type == GTS_ERROR)
+    return;
+  f->token->str[0] = '\0';
+  f->token->len = 0;
+  if (f->next_token != '\0') {
+    if (char_in_string (f->next_token, f->tokens)) {
+      f->line = f->curline;
+      f->pos = f->curpos - 1;
+      g_string_append_c (f->token, f->next_token);
+      f->type = f->next_token;
+      f->next_token = '\0';
+      return;
+    }
+    else {
+      c = f->next_token;
+      f->next_token = '\0';
+    }
+  }
+  else
+    c = gts_file_getc_scope (f);
+  f->type = GTS_NONE;
+  while (c != EOF && (!in_string || !char_in_string (c, f->delimiters))) {
+    if (in_string) {
+      if (char_in_string (c, f->tokens)) {
+	f->next_token = c;
+	break;
+      }
+      g_string_append_c (f->token, c);
+    }
+    else if (!char_in_string (c, f->delimiters)) {
+      in_string = TRUE;
+      f->line = f->curline;
+      f->pos = f->curpos - 1;
+      g_string_append_c (f->token, c);
+      if (char_in_string (c, f->tokens)) {
+	f->type = c;
+	break;
+      }
+    }
+    c = gts_file_getc_scope (f);
+  }
+  if (f->type == GTS_NONE && f->token->len > 0) {
+    gchar * a;
+
+    a = f->token->str;
+    while (*a != '\0' && char_in_string (*a, "+-")) a++;
+    if (*a == '\0') {
+      f->type = GTS_STRING;
+      return;
+    }
+    a = f->token->str;
+    while (*a != '\0' && char_in_string (*a, "+-0123456789")) a++;
+    if (*a == '\0') {
+      f->type = GTS_INT;
+      return;
+    }
+    a = f->token->str;
+    while (*a != '\0' && char_in_string (*a, "+-eE.")) a++;
+    if (*a == '\0') {
+      f->type = GTS_STRING;
+      return;
+    }
+    a = f->token->str;
+    while (*a != '\0' && char_in_string (*a, "+-0123456789eE.")) a++;
+    if (*a == '\0') {
+      f->type = GTS_FLOAT;
+      return;
+    }
+    a = f->token->str;
+    if (!strncmp (a, "0x", 2) || 
+	!strncmp (a, "-0x", 3) || 
+	!strncmp (a, "+0x", 3)) {
+      while (*a != '\0' && char_in_string (*a, "+-0123456789abcdefx")) a++;
+      if (*a == '\0') {
+	f->type = GTS_INT;
+	return;
+      }
+      a = f->token->str;
+      while (*a != '\0' && char_in_string (*a, "+-0123456789abcdefx.p")) a++;
+      if (*a == '\0') {
+	f->type = GTS_FLOAT;
+	return;
+      }
+    }
+    f->type = GTS_STRING;
+  }
+}
+
+/**
+ * gts_file_first_token_after:
+ * @f: a #GtsFile.
+ * @type: a #GtsTokenType.
+ *
+ * Finds and sets the first token of a type different from @type 
+ * occuring after a token of type @type.
+ */
+void gts_file_first_token_after (GtsFile * f, GtsTokenType type)
+{
+  g_return_if_fail (f != NULL);
+
+  while (f->type != GTS_ERROR && 
+	 f->type != GTS_NONE &&
+	 f->type != type)
+    gts_file_next_token (f);
+  while (f->type == type)
+    gts_file_next_token (f);
+}
+
+/**
+ * gts_file_assign_start:
+ * @f: a #GtsFile.
+ * @vars: a %GTS_NONE terminated array of #GtsFileVariable.
+ *
+ * Opens a block delimited by braces to read a list of optional
+ * arguments specified by @vars.  
+ *
+ * If an error is encountered the @error field of @f is set.
+ */
+void gts_file_assign_start (GtsFile * f, GtsFileVariable * vars)
+{
+  GtsFileVariable * var;
+
+  g_return_if_fail (f != NULL);
+  g_return_if_fail (vars != NULL);
+
+  var = vars;
+  while (var->type != GTS_NONE)
+    (var++)->set = FALSE;
+
+  if (f->type != '{') {
+    gts_file_error (f, "expecting an opening brace");
+    return;
+  }
+
+  f->scope_max++;
+  gts_file_next_token (f);
+}
+
+/**
+ * gts_file_assign_next:
+ * @f: a #GtsFile.
+ * @vars: a %GTS_NONE terminated array of #GtsFileVariable.
+ *
+ * Assigns the next optional argument of @vars read from @f.
+ *
+ * Returns: the variable of @vars which has been assigned or %NULL if
+ * no variable has been assigned (if an error has been encountered the
+ * @error field of @f is set).  
+ */
+GtsFileVariable * gts_file_assign_next (GtsFile * f, GtsFileVariable * vars)
+{
+  GtsFileVariable * var;
+  gboolean found = FALSE;
+
+  g_return_val_if_fail (f != NULL, NULL);
+  g_return_val_if_fail (vars != NULL, NULL);
+
+  while (f->type == '\n')
+    gts_file_next_token (f);
+  if (f->type == '}') {
+    f->scope_max--;
+    gts_file_next_token (f);
+    return NULL;
+  }
+  if (f->type == GTS_ERROR)
+    return NULL;
+
+  var = vars;
+  while (f->type != GTS_ERROR && var->type != GTS_NONE && !found) {
+    if (!strcmp (var->name, f->token->str)) {
+      found = TRUE;
+      if (var->unique && var->set)
+	gts_file_error (f, "variable `%s' was already set at line %d:%d", 
+			var->name, var->line, var->pos);
+      else {
+	var->line = f->line;
+	var->pos = f->pos;
+	gts_file_next_token (f);
+	if (f->type != '=')
+	  gts_file_error (f, "expecting `='");
+	else {
+	  var->set = TRUE;
+	  switch (var->type) {
+	  case GTS_FILE:
+	    break;
+	  case GTS_INT:
+	    gts_file_next_token (f);
+	    if (f->type != GTS_INT) {
+	      gts_file_error (f, "expecting an integer");
+	      var->set = FALSE;
+	    }
+	    else if (var->data)
+	      *((gint *) var->data) = atoi (f->token->str); 
+	    break;
+	  case GTS_UINT:
+	    gts_file_next_token (f);
+	    if (f->type != GTS_INT) {
+	      gts_file_error (f, "expecting an integer");
+	      var->set = FALSE;
+	    }
+	    else if (var->data)
+	      *((guint *) var->data) = atoi (f->token->str); 
+	    break;
+	  case GTS_FLOAT:
+	    gts_file_next_token (f);
+	    if (f->type != GTS_INT && f->type != GTS_FLOAT) {
+	      gts_file_error (f, "expecting a number");
+	      var->set = FALSE;
+	    }
+	    else if (var->data)
+	      *((gfloat *) var->data) = atof (f->token->str); 
+	    break;
+	  case GTS_DOUBLE:
+	    gts_file_next_token (f);
+	    if (f->type != GTS_INT && f->type != GTS_FLOAT) {
+	      gts_file_error (f, "expecting a number");
+	      var->set = FALSE;
+	    }
+	    else if (var->data)
+	      *((gdouble *) var->data) = atof (f->token->str); 
+	    break;
+	  case GTS_STRING:
+	    gts_file_next_token (f);
+	    if (f->type != GTS_INT && 
+		f->type != GTS_FLOAT && 
+		f->type != GTS_STRING) {
+	      gts_file_error (f, "expecting a string");
+	      var->set = FALSE;
+	    }
+	    else if (var->data)
+	      *((gchar **) var->data) = g_strdup (f->token->str); 
+	    break;
+	  default:
+	    g_assert_not_reached ();
+	  }
+	}
+      }
+    }
+    else
+      var++;
+  }
+  if (!found)
+    gts_file_error (f, "unknown identifier `%s'", f->token->str);
+  else if (f->type != GTS_ERROR) {
+    g_assert (var->set);
+    gts_file_next_token (f);
+    return var;
+  }
+  return NULL;
+}
+
+/**
+ * gts_file_assign_variables:
+ * @f: a #GtsFile.
+ * @vars: an array of #GtsFileVariable.
+ *
+ * Assigns all the variables belonging to @vars found in @f.
+ *
+ * If an error is encountered the @error field of @f is set.
+ */
+void gts_file_assign_variables (GtsFile * f, GtsFileVariable * vars)
+{
+  g_return_if_fail (f != NULL);
+  g_return_if_fail (vars != NULL);
+
+  gts_file_assign_start (f, vars);
+  while (gts_file_assign_next (f, vars))
+    ;
+}
+
+/**
+ * gts_file_variable_error:
+ * @f: a #GtsFile.
+ * @vars: an array of #GtsFileVariable.
+ * @name: the name of a variable in @vars.
+ * @format: the standard sprintf() format string.
+ * @...: the parameters to insert into the format string.
+ *
+ * Sets the @error field of @f using gts_file_verror().
+ *
+ * String @name must match one of the variable names in @vars.
+ *
+ * If variable @name has been assigned (using gts_file_assign_variables())
+ * sets the @line and @pos fields of @f to the line and position where
+ * it has been assigned.
+ */
+void gts_file_variable_error (GtsFile * f, 
+			      GtsFileVariable * vars,
+			      const gchar * name,
+			      const gchar * format,
+			      ...)
+{
+  va_list args;
+  GtsFileVariable * var;
+
+  g_return_if_fail (f != NULL);
+  g_return_if_fail (vars != NULL);
+  g_return_if_fail (name != NULL);
+  g_return_if_fail (format != NULL);
+
+  var = vars;
+  while (var->type != GTS_NONE && strcmp (var->name, name))
+    var++;
+
+  g_return_if_fail (var->type != GTS_NONE); /* @name not found in @vars */
+
+  if (var->set) {
+    f->line = var->line;
+    f->pos = var->pos;
+  }
+
+  va_start (args, format);  
+  gts_file_verror (f, format, args);
+  va_end (args);
+}
+
+#ifdef DEBUG_FUNCTIONS
+static GHashTable * ids = NULL;
+static guint next_id = 1;
+
+guint id (gpointer p)
+{
+  g_return_val_if_fail (p != NULL, 0);
+  g_return_val_if_fail (ids != NULL, 0);
+  g_assert (g_hash_table_lookup (ids, p));
+  return GPOINTER_TO_UINT (g_hash_table_lookup (ids, p));
+}
+
+void id_insert (gpointer p)
+{
+  g_return_if_fail (p != NULL);
+  if (ids == NULL) ids = g_hash_table_new (NULL, NULL);
+  g_assert (g_hash_table_lookup (ids, p) == NULL);
+  g_hash_table_insert (ids, p, GUINT_TO_POINTER (next_id++));
+}
+
+void id_remove (gpointer p)
+{
+  g_assert (g_hash_table_lookup (ids, p));  
+  g_hash_table_remove (ids, p);
+}
+
+void gts_write_triangle (GtsTriangle * t, 
+			 GtsPoint * o,
+			 FILE * fptr)
+{
+  gdouble xo = o ? o->x : 0.0;
+  gdouble yo = o ? o->y : 0.0;
+  gdouble zo = o ? o->z : 0.0;
+
+  g_return_if_fail (t != NULL && fptr != NULL);
+
+  fprintf (fptr, "(hdefine geometry \"t%d\" { =\n", id (t));
+  fprintf (fptr, "OFF 3 1 0\n"
+	   "%g %g %g\n%g %g %g\n%g %g %g\n3 0 1 2\n})\n"
+	   "(geometry \"t%d\" { : \"t%d\"})\n"
+	   "(normalization \"t%d\" none)\n",
+	   GTS_POINT (GTS_SEGMENT (t->e1)->v1)->x - xo, 
+	   GTS_POINT (GTS_SEGMENT (t->e1)->v1)->y - yo,
+	   GTS_POINT (GTS_SEGMENT (t->e1)->v1)->z - zo,
+	   GTS_POINT (GTS_SEGMENT (t->e1)->v2)->x - xo, 
+	   GTS_POINT (GTS_SEGMENT (t->e1)->v2)->y - yo, 
+	   GTS_POINT (GTS_SEGMENT (t->e1)->v2)->z - zo,
+	   GTS_POINT (gts_triangle_vertex (t))->x - xo,
+	   GTS_POINT (gts_triangle_vertex (t))->y - yo,
+	   GTS_POINT (gts_triangle_vertex (t))->z - zo,
+	   id (t), id (t), id (t));
+}
+
+void gts_write_segment (GtsSegment * s, 
+			GtsPoint * o,
+			FILE * fptr)
+{
+  gdouble xo = o ? o->x : 0.0;
+  gdouble yo = o ? o->y : 0.0;
+  gdouble zo = o ? o->z : 0.0;
+
+  g_return_if_fail (s != NULL && fptr != NULL);
+
+  fprintf (fptr, "(geometry \"s%d\" { =\n", id (s));
+  fprintf (fptr, "VECT 1 2 0 2 0 %g %g %g %g %g %g })\n"
+	   "(normalization \"s%d\" none)\n",
+	   GTS_POINT (s->v1)->x - xo, 
+	   GTS_POINT (s->v1)->y - yo, 
+	   GTS_POINT (s->v1)->z - zo,
+	   GTS_POINT (s->v2)->x - xo, 
+	   GTS_POINT (s->v2)->y - yo, 
+	   GTS_POINT (s->v2)->z - zo,
+	   id (s));
+}
+#endif /* DEBUG_FUNCTIONS */
diff --git a/gts/named.c b/gts/named.c
new file mode 100644
index 0000000..379f9f6
--- /dev/null
+++ b/gts/named.c
@@ -0,0 +1,188 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <string.h>
+#include "gts.h"
+
+static void nvertex_read (GtsObject ** po, GtsFile * fp)
+{
+  if ((*po)->klass->parent_class->read)
+    (* (*po)->klass->parent_class->read) (po, fp);
+
+  if (fp->type != '\n' && fp->type != GTS_ERROR) {
+    strncpy (GTS_NVERTEX (*po)->name, fp->token->str, GTS_NAME_LENGTH);
+    gts_file_next_token (fp);
+  }
+}
+
+static void nvertex_write (GtsObject * o, FILE * fptr)
+{
+  GtsNVertex * nv = GTS_NVERTEX (o);
+
+  (* o->klass->parent_class->write) (o, fptr);
+  if (nv->name[0] != '\0')
+    fprintf (fptr, " %s", nv->name);
+}
+
+static void nvertex_class_init (GtsNVertexClass * klass)
+{
+  GTS_OBJECT_CLASS (klass)->read = nvertex_read;
+  GTS_OBJECT_CLASS (klass)->write = nvertex_write;
+}
+
+static void nvertex_init (GtsNVertex * nvertex)
+{
+  nvertex->name[0] = '\0';
+}
+
+/**
+ * gts_nvertex_class:
+ *
+ * Returns: the #GtsNVertexClass.
+ */
+GtsNVertexClass * gts_nvertex_class (void)
+{
+  static GtsNVertexClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo nvertex_info = {
+      "GtsNVertex",
+      sizeof (GtsNVertex),
+      sizeof (GtsNVertexClass),
+      (GtsObjectClassInitFunc) nvertex_class_init,
+      (GtsObjectInitFunc) nvertex_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_vertex_class ()), 
+				  &nvertex_info);
+  }
+
+  return klass;
+}
+
+static void nedge_read (GtsObject ** po, GtsFile * fp)
+{
+  if (fp->type != GTS_STRING) {
+    gts_file_error (fp, "expecting a string (name)");
+    return;
+  }
+  strncpy (GTS_NEDGE (*po)->name, fp->token->str, GTS_NAME_LENGTH);
+  gts_file_next_token (fp);
+}
+
+static void nedge_write (GtsObject * o, FILE * fptr)
+{
+  GtsNEdge * ne = GTS_NEDGE (o);
+
+  if (ne->name[0] != '\0')
+    fprintf (fptr, " %s", ne->name);
+}
+
+static void nedge_class_init (GtsNEdgeClass * klass)
+{
+  GTS_OBJECT_CLASS (klass)->read = nedge_read;
+  GTS_OBJECT_CLASS (klass)->write = nedge_write;
+}
+
+static void nedge_init (GtsNEdge * nedge)
+{
+  nedge->name[0] = '\0';
+}
+
+/**
+ * gts_nedge_class:
+ *
+ * Returns: the #GtsNEdgeClass.
+ */
+GtsNEdgeClass * gts_nedge_class (void)
+{
+  static GtsNEdgeClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo nedge_info = {
+      "GtsNEdge",
+      sizeof (GtsNEdge),
+      sizeof (GtsNEdgeClass),
+      (GtsObjectClassInitFunc) nedge_class_init,
+      (GtsObjectInitFunc) nedge_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_edge_class ()), 
+				  &nedge_info);
+  }
+
+  return klass;
+}
+
+static void nface_read (GtsObject ** po, GtsFile * fp)
+{
+  if (fp->type != GTS_STRING) {
+    gts_file_error (fp, "expecting a string (name)");
+    return;
+  }
+  strncpy (GTS_NFACE (*po)->name, fp->token->str, GTS_NAME_LENGTH);
+  gts_file_next_token (fp);
+}
+
+static void nface_write (GtsObject * o, FILE * fptr)
+{
+  GtsNFace * nf = GTS_NFACE (o);
+
+  if (nf->name[0] != '\0')
+    fprintf (fptr, " %s", GTS_NFACE (o)->name);
+}
+
+static void nface_class_init (GtsNFaceClass * klass)
+{
+  GTS_OBJECT_CLASS (klass)->read = nface_read;
+  GTS_OBJECT_CLASS (klass)->write = nface_write;
+}
+
+static void nface_init (GtsNFace * nface)
+{
+  nface->name[0] = '\0';
+}
+
+/**
+ * gts_nface_class:
+ *
+ * Returns: the #GtsNFaceClass.
+ */
+GtsNFaceClass * gts_nface_class (void)
+{
+  static GtsNFaceClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo nface_info = {
+      "GtsNFace",
+      sizeof (GtsNFace),
+      sizeof (GtsNFaceClass),
+      (GtsObjectClassInitFunc) nface_class_init,
+      (GtsObjectInitFunc) nface_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_face_class ()), 
+				  &nface_info);
+  }
+
+  return klass;
+}
diff --git a/gts/object.c b/gts/object.c
new file mode 100644
index 0000000..5970e50
--- /dev/null
+++ b/gts/object.c
@@ -0,0 +1,345 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <string.h>
+#include "gts.h"
+#include "gts-private.h"
+
+static GHashTable * class_table = NULL;
+
+static void gts_object_class_init (GtsObjectClass * klass,
+				   GtsObjectClass * parent_class)
+{
+  if (parent_class) {
+    gts_object_class_init (klass, parent_class->parent_class);
+    if (parent_class->info.class_init_func)
+      (*parent_class->info.class_init_func) (klass);
+  }
+}
+
+/**
+ * gts_object_class_new:
+ * @parent_class: a #GtsObjectClass.
+ * @info: a #GtsObjectClassInfo, description of the new class to create.
+ *
+ * Returns: a new #GtsObjectClass derived from @parent_class and described by
+ * @info.
+ */
+gpointer gts_object_class_new (GtsObjectClass * parent_class,
+			       GtsObjectClassInfo * info)
+{
+  GtsObjectClass * klass;
+
+  g_return_val_if_fail (info != NULL, NULL);
+  g_return_val_if_fail (parent_class == NULL ||
+			info->object_size >= parent_class->info.object_size,
+			NULL);
+  g_return_val_if_fail (parent_class == NULL ||
+			info->class_size >= parent_class->info.class_size,
+			NULL);
+
+  klass = g_malloc0 (info->class_size);
+  klass->info = *info;
+  klass->parent_class = parent_class;
+  gts_object_class_init (klass, klass);
+
+  if (!class_table)
+    class_table = g_hash_table_new (g_str_hash, g_str_equal);
+  g_hash_table_insert (class_table, klass->info.name, klass);
+
+  return klass;
+}
+
+/**
+ * gts_object_class_from_name:
+ * @name: the name of a #GtsObjectClass.
+ *
+ * Returns: the #GtsObjectClass with name @name or %NULL if it hasn't been 
+ * instantiated yet.
+ */
+GtsObjectClass * gts_object_class_from_name (const gchar * name)
+{
+  g_return_val_if_fail (name != NULL, NULL);
+
+  if (!class_table)
+    return NULL;
+  return g_hash_table_lookup (class_table, name);
+}
+
+static void object_destroy (GtsObject * object)
+{
+#ifdef DEBUG_IDENTITY
+#ifdef DEBUG_LEAKS
+  fprintf (stderr, "destroy %s %p->%d\n", 
+	   object->klass->info.name,
+	   object, 
+	   id (object));
+#endif
+  id_remove (object);
+#endif
+  object->klass = NULL;
+  g_free (object);
+}
+
+static void object_clone (GtsObject * clone, GtsObject * object)
+{
+  memcpy (clone, object, object->klass->info.object_size);
+  clone->reserved = NULL;
+}
+
+static void object_class_init (GtsObjectClass * klass)
+{
+  klass->clone = object_clone;
+  klass->destroy = object_destroy;
+  klass->read = NULL;
+  klass->write = NULL;
+  klass->color = NULL;  
+  klass->attributes = NULL;
+}
+
+static void object_init (GtsObject * object)
+{
+  object->reserved = NULL;
+  object->flags = 0;
+}
+
+/**
+ * gts_object_class:
+ *
+ * Returns: the #GtsObjectClass.
+ */
+GtsObjectClass * gts_object_class (void)
+{
+  static GtsObjectClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo object_info = {
+      "GtsObject",
+      sizeof (GtsObject),
+      sizeof (GtsObjectClass),
+      (GtsObjectClassInitFunc) object_class_init,
+      (GtsObjectInitFunc) object_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (NULL, &object_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_object_check_cast:
+ * @object: a #GtsObject.
+ * @klass: a #GtsObjectClass.
+ *
+ * Returns: @object while emitting warnings if @object is not of class @klass.
+ */
+gpointer gts_object_check_cast (gpointer object, 
+				gpointer klass)
+{
+  if (!object) {
+    g_warning ("invalid cast from (NULL) pointer to `%s'",
+	       GTS_OBJECT_CLASS (klass)->info.name);
+    return object;
+  }
+  if (!((GtsObject *) object)->klass) {
+    g_warning ("invalid unclassed pointer in cast to `%s'",
+	       GTS_OBJECT_CLASS (klass)->info.name);
+    return object;
+  }
+  if (!gts_object_is_from_class (object, klass)) {
+    g_warning ("invalid cast from `%s' to `%s'",
+	       ((GtsObject *) object)->klass->info.name,
+	       GTS_OBJECT_CLASS (klass)->info.name);
+    return object;
+  }
+  return object;
+}
+
+/**
+ * gts_object_class_check_cast:
+ * @klass: a #GtsObjectClass.
+ * @from: a #GtsObjectClass.
+ *
+ * Returns: @klass while emitting warnings if @klass is not derived from
+ * @from.
+ */
+gpointer gts_object_class_check_cast (gpointer klass, 
+				      gpointer from)
+{
+  if (!klass) {
+    g_warning ("invalid cast from (NULL) pointer to `%s'",
+	       GTS_OBJECT_CLASS (from)->info.name);
+    return klass;
+  }
+  if (!gts_object_class_is_from_class (klass, from)) {
+    g_warning ("invalid cast from `%s' to `%s'",
+	       GTS_OBJECT_CLASS (klass)->info.name,
+	       GTS_OBJECT_CLASS (from)->info.name);
+    return klass;
+  }
+  return klass;
+}
+
+/**
+ * gts_object_init:
+ * @object: a #GtsObject.
+ * @klass: a #GtsObjectClass.
+ *
+ * Calls the init method of @klass with @object as argument. This is done 
+ * recursively in the correct order (from the base class to the top). You
+ * should rarely need this function as it is called automatically by the
+ * constructor for each class.
+ */
+void gts_object_init (GtsObject * object, GtsObjectClass * klass)
+{
+  GtsObjectClass * parent_class;
+
+  g_return_if_fail (object != NULL);
+  g_return_if_fail (klass != NULL);
+
+  parent_class = klass->parent_class;
+  if (parent_class)
+    gts_object_init (object, parent_class);
+  if (klass->info.object_init_func)
+    (*klass->info.object_init_func) (object);
+}
+
+/**
+ * gts_object_new:
+ * @klass: a #GtsObjectClass.
+ *
+ * Returns: a new initialized object of class @klass.
+ */
+GtsObject * gts_object_new (GtsObjectClass * klass)
+{
+  GtsObject * object;
+
+  g_return_val_if_fail (klass != NULL, NULL);
+
+  object = g_malloc0 (klass->info.object_size);
+  object->klass = klass;
+  gts_object_init (object, klass);
+
+#ifdef DEBUG_IDENTITY
+  id_insert (object);
+#ifdef DEBUG_LEAKS
+  fprintf (stderr, "new %s %p->%d\n", klass->info.name, 
+	   object, 
+	   id (object));
+#endif
+#endif
+
+  return object;
+}
+
+/**
+ * gts_object_clone:
+ * @object: a #GtsObject.
+ *
+ * Calls the clone method of @object. The call to this function will fail
+ * if no clone method exists for the given object.
+ *
+ * Returns: a new object clone of @object.
+ */
+GtsObject * gts_object_clone (GtsObject * object)
+{
+  GtsObject * clone;
+
+  g_return_val_if_fail (object != NULL, NULL);
+  g_return_val_if_fail (object->klass->clone, NULL);
+
+  clone = g_malloc0 (object->klass->info.object_size);
+  clone->klass = object->klass;
+  object_init (clone);
+  (* object->klass->clone) (clone, object);
+
+#ifdef DEBUG_IDENTITY
+  id_insert (clone);
+#ifdef DEBUG_LEAKS
+  fprintf (stderr, "clone %s %p->%d\n", clone->klass->info.name, 
+	   clone, 
+	   id (clone));
+#endif
+#endif
+
+  return clone;
+}
+
+/**
+ * gts_object_destroy:
+ * @object: a #GtsObject.
+ *
+ * Calls the destroy method of @object, freeing all memory allocated for it.
+ */
+void gts_object_destroy (GtsObject * object)
+{
+  g_assert (object->klass->destroy);
+  GTS_OBJECT_SET_FLAGS (object, GTS_DESTROYED);
+  (* object->klass->destroy) (object);
+}
+
+/**
+ * gts_object_reset_reserved:
+ * @object: a #GtsObject.
+ *
+ * Reset the reserved field of @object.
+ */
+void gts_object_reset_reserved (GtsObject * object)
+{
+  g_return_if_fail (object != NULL);
+
+  object->reserved = NULL;
+}
+
+/**
+ * gts_object_attributes:
+ * @object: a #GtsObject.
+ * @from: a #GtsObject.
+ *
+ * Calls the attributes() method of @object using @from as source.
+ */
+void gts_object_attributes (GtsObject * object, GtsObject * from)
+{
+  g_return_if_fail (object != NULL);
+
+  if (object->klass->attributes)
+    (* object->klass->attributes) (object, from);
+}
+
+static void free_class (gchar * name, GtsObjectClass * klass)
+{
+  g_free (klass);
+}
+
+/**
+ * gts_finalize:
+ *
+ * Free all the memory allocated by the object system of GTS. No other
+ * GTS function can be called after this function has been called.
+ */
+void gts_finalize (void)
+{
+  if (class_table) {
+    g_hash_table_foreach (class_table, (GHFunc) free_class, NULL);
+    g_hash_table_destroy (class_table);
+    class_table = NULL;
+  }
+}
diff --git a/gts/oocs.c b/gts/oocs.c
new file mode 100644
index 0000000..f0d76bf
--- /dev/null
+++ b/gts/oocs.c
@@ -0,0 +1,387 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <math.h>
+#include "gts.h"
+
+static void cluster_destroy (GtsObject * object)
+{
+  GtsCluster * c = GTS_CLUSTER (object);
+
+  if (c->v && gts_vertex_is_unattached (c->v))
+    gts_object_destroy (GTS_OBJECT (c->v));
+
+  /* do not forget to call destroy method of the parent */
+  (* GTS_OBJECT_CLASS (gts_cluster_class ())->parent_class->destroy) (object);
+}
+
+static void cluster_add (GtsCluster * c, GtsPoint * p, gpointer data)
+{
+  GtsPoint * cp;
+
+  g_return_if_fail (c != NULL);
+  g_return_if_fail (c->v != NULL);
+  g_return_if_fail (p != NULL);
+
+  cp = GTS_POINT (c->v);
+  
+  cp->x += p->x;
+  cp->y += p->y;
+  cp->z += p->z;
+  c->n++;
+}
+
+static void cluster_update (GtsCluster * c)
+{
+  GtsPoint * p;
+
+  g_return_if_fail (c != NULL);
+  g_return_if_fail (c->v != NULL);
+
+  if (c->n > 1) {
+    p = GTS_POINT (c->v);
+    p->x /= c->n;
+    p->y /= c->n;
+    p->z /= c->n;
+  }
+}
+
+static void cluster_class_init (GtsClusterClass * klass)
+{
+  klass->add = cluster_add;
+  klass->update = cluster_update;
+
+  GTS_OBJECT_CLASS (klass)->destroy = cluster_destroy;
+}
+
+static void cluster_init (GtsCluster * c)
+{
+  c->v = NULL;
+  c->n = 0;
+}
+
+/**
+ * gts_cluster_class:
+ *
+ * Returns: the #GtsClusterClass.
+ */
+GtsClusterClass * gts_cluster_class (void)
+{
+  static GtsClusterClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo cluster_info = {
+      "GtsCluster",
+      sizeof (GtsCluster),
+      sizeof (GtsClusterClass),
+      (GtsObjectClassInitFunc) cluster_class_init,
+      (GtsObjectInitFunc) cluster_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (gts_object_class (), &cluster_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_cluster_new:
+ * @klass: a #GtsClusterClass.
+ * @id: the id of the new cluster.
+ * @vklass: a #GtsVertexClass for the representative vertex of the cluster.
+ *
+ * Returns: a new #GtsCluster.
+ */
+GtsCluster * gts_cluster_new (GtsClusterClass * klass,
+			      GtsClusterId id,
+			      GtsVertexClass * vklass)
+{
+  GtsCluster * c;
+
+  c = GTS_CLUSTER (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  c->id = id;
+  c->v = gts_vertex_new (vklass, 0., 0., 0.);
+
+  return c;
+}
+
+/**
+ * gts_cluster_add:
+ * @c: a #GtsCluster.
+ * @p: a #GtsPoint.
+ * @data: data to pass to the add() virtual method of #GtsClusterClass.
+ *
+ * Adds point @p to cluster @c.
+ */
+void gts_cluster_add (GtsCluster * c, GtsPoint * p, gpointer data)
+{
+  g_return_if_fail (c != NULL);
+  g_return_if_fail (p != NULL);
+
+  (* GTS_CLUSTER_CLASS (GTS_OBJECT (c)->klass)->add) (c, p, data);
+}
+
+/**
+ * gts_cluster_update:
+ * @c: a #GtsCluster.
+ *
+ * Updates the position of the vertex representative of all the
+ * vertices added to @c.  
+ */
+void gts_cluster_update (GtsCluster * c)
+{
+  g_return_if_fail (c != NULL);
+
+  (* GTS_CLUSTER_CLASS (GTS_OBJECT (c)->klass)->update) (c);
+}
+
+static void destroy_cluster (GtsClusterId * id, GtsObject * cluster)
+{
+  gts_object_destroy (cluster);
+}
+
+static void cluster_grid_destroy (GtsObject * object)
+{
+  GtsClusterGrid * cluster_grid = GTS_CLUSTER_GRID (object);
+
+  g_hash_table_foreach (cluster_grid->clusters, 
+			(GHFunc) destroy_cluster, NULL);
+  g_hash_table_destroy (cluster_grid->clusters);
+  
+  (* GTS_OBJECT_CLASS (gts_cluster_grid_class ())->parent_class->destroy) 
+    (object);
+}
+
+static void cluster_grid_class_init (GtsClusterGridClass * klass)
+{
+  GTS_OBJECT_CLASS (klass)->destroy = cluster_grid_destroy;
+}
+
+static gint cluster_id_equal (gconstpointer v1,
+			      gconstpointer v2)
+{
+  const GtsClusterId * id1 = (const GtsClusterId *) v1;
+  const GtsClusterId * id2 = (const GtsClusterId *) v2;
+  return ((id1->x == id2->x) && (id1->y == id2->y) && (id1->z == id2->z));
+}
+
+static guint cluster_id_hash (gconstpointer key)
+{
+  const GtsClusterId * id = (const GtsClusterId *) key;
+  return id->x + id->y + id->z;
+}
+
+static void cluster_grid_init (GtsClusterGrid * cluster_grid)
+{
+  cluster_grid->surface = NULL;
+  cluster_grid->bbox = NULL;
+  cluster_grid->cluster_class = gts_cluster_class ();
+  cluster_grid->clusters = g_hash_table_new (cluster_id_hash,
+					      cluster_id_equal);
+}
+
+/**
+ * gts_cluster_grid_class:
+ *
+ * Returns: the #GtsClusterGridClass.
+ */
+GtsClusterGridClass * gts_cluster_grid_class (void)
+{
+  static GtsClusterGridClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo cluster_grid_info = {
+      "GtsClusterGrid",
+      sizeof (GtsClusterGrid),
+      sizeof (GtsClusterGridClass),
+      (GtsObjectClassInitFunc) cluster_grid_class_init,
+      (GtsObjectInitFunc) cluster_grid_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (gts_object_class (), &cluster_grid_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_cluster_grid_new:
+ * @klass: a #GtsClusterGridClass.
+ * @cluster_class: the klass to be used for the vertex clusters.
+ * @s: the simplified surface.
+ * @bbox: bounding box of the surface to be simplified.
+ * @delta: the size of one grid cell of the simplification grid.
+ *
+ * Returns: a new #GtsClusterGrid.
+ */
+GtsClusterGrid * gts_cluster_grid_new (GtsClusterGridClass * klass,
+				       GtsClusterClass * cluster_class,
+				       GtsSurface * s,
+				       GtsBBox * bbox,
+				       gdouble delta)
+{
+  GtsClusterGrid * cluster_grid;
+  GtsVector size;
+
+  g_return_val_if_fail (klass != NULL, NULL);
+  g_return_val_if_fail (cluster_class != NULL, NULL);
+  g_return_val_if_fail (s != NULL, NULL);
+  g_return_val_if_fail (bbox != NULL, NULL);
+  g_return_val_if_fail (delta > 0., NULL);
+
+  size[0] = ceil ((bbox->x2 - bbox->x1)/delta);
+  size[1] = ceil ((bbox->y2 - bbox->y1)/delta);
+  size[2] = ceil ((bbox->z2 - bbox->z1)/delta);
+  g_return_val_if_fail (size[0] <= 2.*G_MAXINT + 2. &&
+			size[1] <= 2.*G_MAXINT + 2. &&
+			size[2] <= 2.*G_MAXINT + 2., NULL);
+  cluster_grid = 
+    GTS_CLUSTER_GRID (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  cluster_grid->cluster_class = cluster_class;
+  cluster_grid->surface = s;
+  cluster_grid->bbox = bbox;
+  cluster_grid->size[0] = size[0];
+  cluster_grid->size[1] = size[1];
+  cluster_grid->size[2] = size[2];
+
+  return cluster_grid;
+}
+
+static GtsClusterId cluster_index (GtsPoint * p,
+				   GtsBBox * bb,
+				   GtsVector n)
+{
+  GtsClusterId id = {0, 0, 0};
+  
+  g_return_val_if_fail (p->x >= bb->x1 && p->x <= bb->x2, id);
+  g_return_val_if_fail (p->y >= bb->y1 && p->y <= bb->y2, id);
+  g_return_val_if_fail (p->z >= bb->z1 && p->z <= bb->z2, id);
+  
+  id.x = (guint) (p->x == bb->x2 ? n[0] - 1. : n[0]*(p->x - bb->x1)/(bb->x2 - bb->x1));
+  id.y = (guint) (p->y == bb->y2 ? n[1] - 1. : n[1]*(p->y - bb->y1)/(bb->y2 - bb->y1));
+  id.z = (guint) (p->z == bb->z2 ? n[2] - 1. : n[2]*(p->z - bb->z1)/(bb->z2 - bb->z1));
+
+  return id;
+}
+
+static GtsCluster * cluster_grid_add_point (GtsClusterGrid * cluster_grid,
+					    GtsPoint * p,
+					    gpointer data)
+{
+  GtsClusterId id = cluster_index (p, 
+				   cluster_grid->bbox, 
+				   cluster_grid->size);
+  GtsCluster * c = g_hash_table_lookup (cluster_grid->clusters, &id);
+
+  if (c == NULL) {
+    c = gts_cluster_new (cluster_grid->cluster_class, id, 
+			 cluster_grid->surface->vertex_class);
+    g_hash_table_insert (cluster_grid->clusters, &c->id, c);
+  }
+  
+  gts_cluster_add (c, p, data);
+  
+  return c;
+}
+
+/**
+ * gts_cluster_grid_add_triangle:
+ * @cluster_grid: a #GtsClusterGrid.
+ * @p1: a #GtsPoint.
+ * @p2: a #GtsPoint.
+ * @p3: a #GtsPoint.
+ * @data: user data to pass to the cluster add() method.
+ *
+ * Adds the triangle defined by @p1, @p2 and @p3 to the respective clusters
+ * of @cluster_grid.
+ */
+void gts_cluster_grid_add_triangle (GtsClusterGrid * cluster_grid,
+				    GtsPoint * p1,
+				    GtsPoint * p2,
+				    GtsPoint * p3,
+				    gpointer data)
+{
+  GtsCluster * c1, * c2, * c3;
+
+  g_return_if_fail (cluster_grid != NULL);
+  g_return_if_fail (p1 != NULL);
+  g_return_if_fail (p2 != NULL);
+  g_return_if_fail (p3 != NULL);
+  g_return_if_fail (cluster_grid->surface != NULL);
+
+  c1 = cluster_grid_add_point (cluster_grid, p1, data);
+  c2 = cluster_grid_add_point (cluster_grid, p2, data);
+  c3 = cluster_grid_add_point (cluster_grid, p3, data);
+  
+  if (c1 != c2 && c2 != c3 && c3 != c1) {
+    GtsVertex * v1, * v2, * v3;
+    GtsEdge * e1, * e2, * e3;
+    gboolean new_edge = FALSE;
+    
+    v1 = c1->v; v2 = c2->v; v3 = c3->v;
+
+    if ((e1 = GTS_EDGE (gts_vertices_are_connected (v1, v2))) == NULL) {
+      e1 = gts_edge_new (cluster_grid->surface->edge_class, v1, v2);
+      new_edge = TRUE;
+    }
+    if ((e2 = GTS_EDGE (gts_vertices_are_connected (v2, v3))) == NULL) {
+      e2 = gts_edge_new (cluster_grid->surface->edge_class, v2, v3);
+      new_edge = TRUE;
+    }
+    if ((e3 = GTS_EDGE (gts_vertices_are_connected (v3, v1))) == NULL) {
+      e3 = gts_edge_new (cluster_grid->surface->edge_class, v3, v1);
+      new_edge = TRUE;
+    }
+    if (new_edge || !gts_triangle_use_edges (e1, e2, e3))
+      gts_surface_add_face (cluster_grid->surface, 
+			    gts_face_new (cluster_grid->surface->face_class, 
+					  e1, e2, e3));
+  }
+}
+
+static void update_cluster (gint * id, GtsCluster * cluster, GtsRange * stats)
+{
+  gts_cluster_update (cluster);
+  gts_range_add_value (stats, cluster->n);
+}
+
+/**
+ * gts_cluster_grid_update:
+ * @cluster_grid: a #GtsClusterGrid.
+ *
+ * Updates the representative vertices of all the clusters of @cluster_grid.
+ *
+ * Returns: a #GtsRange describing the statistics for the number of vertices
+ * added to each cluster of @cluster_grid.
+ */
+GtsRange gts_cluster_grid_update (GtsClusterGrid * cluster_grid)
+{
+  GtsRange stats;
+
+  gts_range_init (&stats);
+  g_return_val_if_fail (cluster_grid != NULL, stats);
+
+  g_hash_table_foreach (cluster_grid->clusters, 
+			(GHFunc) update_cluster, &stats);
+  gts_range_update (&stats);
+
+  return stats;
+}
diff --git a/gts/partition.c b/gts/partition.c
new file mode 100644
index 0000000..16dc0e1
--- /dev/null
+++ b/gts/partition.c
@@ -0,0 +1,1219 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <math.h>
+
+#include "gts.h"
+
+/* #define DEBUG */
+
+/* Graph partition */
+
+/**
+ * gts_graph_partition_edges_cut:
+ * @partition: a list of @GtsGraph representing a partition.
+ *
+ * Returns: the number of edges cut by the partition.
+ */
+guint gts_graph_partition_edges_cut (GSList * partition)
+{
+  guint cuts = 0;
+
+  while (partition) {
+    cuts += gts_graph_edges_cut (partition->data);
+    partition = partition->next;
+  }
+
+  return cuts/2;
+}
+
+/**
+ * gts_graph_partition_edges_cut_weight:
+ * @partition: a list of @GtsGraph representing a partition.
+ *
+ * Returns: the total weight of the edges cut by the partition.
+ */
+gfloat gts_graph_partition_edges_cut_weight (GSList * partition)
+{
+  gfloat weight = 0.;
+
+  while (partition) {
+    weight += gts_graph_edges_cut_weight (partition->data);
+    partition = partition->next;
+  }
+
+  return weight/2.;
+}
+
+/**
+ * gts_graph_partition_print_stats:
+ * @partition: a list of @GtsGraph representing a partition.
+ * @fp: a file pointer.
+ *
+ * Writes to @fp a summary of the properties of @partition.
+ */
+void gts_graph_partition_print_stats (GSList * partition,
+				      FILE * fp)
+{
+  GtsRange weight;
+  GSList * i;
+
+  g_return_if_fail (partition != NULL);
+  g_return_if_fail (fp != NULL);
+
+  gts_range_init (&weight);
+  i = partition;
+  while (i) {
+    gts_range_add_value (&weight, gts_graph_weight (i->data));
+    i = i->next;
+  }
+  gts_range_update (&weight);
+
+  fprintf (fp, 
+	   "# parts: %d\n"
+	   "#   edge cuts: %5d edge cuts weight: %5g\n"
+	   "#   weight: ",
+	   g_slist_length (partition),
+	   gts_graph_partition_edges_cut (partition),
+	   gts_graph_partition_edges_cut_weight (partition));
+  gts_range_print (&weight, fp);
+  fputc ('\n', fp);
+}
+
+/**
+ * gts_graph_partition_balance:
+ * @partition: a list of @GtsGraph representing a partition.
+ *
+ * Returns: the difference between the maximum and the minimum weight
+ * of the graphs in @partition.  
+ */
+gfloat gts_graph_partition_balance (GSList * partition)
+{
+  gfloat wmin = G_MAXFLOAT;
+  gfloat wmax = - G_MAXFLOAT;
+
+  g_return_val_if_fail (partition != NULL, 0.);
+
+  while (partition) {
+    gfloat weight = gts_graph_weight (partition->data);
+    if (weight < wmin)
+      wmin = weight;
+    if (weight > wmax)
+      wmax = weight;
+    partition = partition->next;
+  }
+  return wmax - wmin;
+}
+
+/**
+ * gts_graph_partition_clone:
+ * @partition: a list of @GtsGraph representing a partition.
+ *
+ * Returns: a new partition clone of @partition (i.e. a list of new
+ * graphs clones of the graphs in @partition).  
+ */
+GSList * gts_graph_partition_clone (GSList * partition)
+{
+  GSList * cparts = NULL;
+
+  while (partition) {
+    cparts = 
+      g_slist_prepend (cparts, 
+		       gts_object_clone (GTS_OBJECT (partition->data)));
+    partition = partition->next;
+  }
+  return cparts;
+}
+
+/**
+ * gts_graph_partition_destroy:
+ * @partition: a list of @GtsGraph representing a partition.
+ *
+ * Destroys all the graphs in @partition and frees @partition.
+ */
+void gts_graph_partition_destroy (GSList * partition)
+{
+  GSList * i = partition;
+
+  while (i) {
+    gts_object_destroy (GTS_OBJECT (i->data));
+    i = i->next;
+  }
+  g_slist_free (partition);
+}
+
+static void find_smallest_degree (GtsGNode * n, gpointer * data)
+{
+  GtsGNode ** nmin = data[0];
+  GtsGraph * g = data[1];
+  guint * min = data[2];
+  guint degree = gts_gnode_degree (n, g);
+
+  if (degree < *min) {
+    *min = degree;
+    *nmin = n;
+  }
+}
+
+static gint graph_comp_weight (GtsGraph * g1, GtsGraph * g2)
+{
+  if (gts_graph_weight (g1) > gts_graph_weight (g2))
+    return 1;
+  return -1;
+}
+
+static void partition_update (GSList * list, GtsGraph * g)
+{
+  GSList * i;
+  GtsGraph * g1;
+  GtsHeap * size_heap;
+  gboolean reinit = TRUE;
+
+  /* initialize traversals */
+  i = list;
+  while (i) {
+    GtsGNode * seed = GTS_OBJECT (i->data)->reserved;
+    GTS_OBJECT (seed)->reserved = 
+      gts_graph_traverse_new (g, seed, GTS_BREADTH_FIRST, reinit);
+    reinit = FALSE;
+    i = i->next;
+  }
+  
+  size_heap = gts_heap_new ((GCompareFunc) graph_comp_weight);
+  i = list;
+  while (i) {
+    gts_heap_insert (size_heap, i->data);
+    i = i->next;
+  }
+  while ((g1 = gts_heap_remove_top (size_heap))) {
+    GtsGraphTraverse * t = GTS_OBJECT (GTS_OBJECT (g1)->reserved)->reserved;
+    GtsGNode * n = gts_graph_traverse_next (t);
+    if (n) {
+      gts_container_add (GTS_CONTAINER (g1), GTS_CONTAINEE (n));
+      gts_heap_insert (size_heap, g1);
+    }
+  }
+  gts_heap_destroy (size_heap);
+
+  /* destroy traversals */
+  i = list;
+  while (i) {
+    GtsGNode * seed = GTS_OBJECT (i->data)->reserved;
+    gts_graph_traverse_destroy (GTS_OBJECT (seed)->reserved);
+    GTS_OBJECT (seed)->reserved = NULL;
+    i = i->next;
+  }
+}
+
+static void better_seed (GtsGNode * n, gpointer * data)
+{
+  guint * sum = data[0];
+  GtsGNode ** seed = data[1];
+  GtsGraph * g = data[2];
+  guint sum1 = gts_graph_distance_sum (g, n);
+  
+  if (sum1 < *sum) {
+    *sum = sum1;
+    *seed = n;
+  }
+}
+
+static GtsGNode * graph_new_seed (GtsGraph * g, GtsGNode * seed)
+{
+  guint sum = gts_graph_distance_sum (g, seed);
+  gpointer data[3];
+  GtsGNode * new_seed = seed;
+
+  data[0] = &sum;
+  data[1] = &new_seed;
+  data[2] = g;
+  gts_gnode_foreach_neighbor (seed, g, (GtsFunc) better_seed, data);
+
+  return new_seed;
+}
+
+/**
+ * gts_graph_bubble_partition:
+ * @g: a #GtsGraph.
+ * @np: number of partitions.
+ * @niter: the maximum number of iterations.
+ * @step_info: a #GtsFunc or %NULL.
+ * @data: user data to pass to @step_info.
+ *
+ * An implementation of the "bubble partitioning algorithm" of
+ * Diekmann, Preis, Schlimbach and Walshaw (2000). The maximum number
+ * of iteration on the positions of the graph growing seeds is
+ * controlled by @niter.
+ *
+ * If not %NULL @step_info is called after each iteration on the seeds
+ * positions passing the partition (a GSList) as argument.
+ *
+ * Returns: a list of @np new #GtsGraph representing the partition.  
+ */
+GSList * gts_graph_bubble_partition (GtsGraph * g, 
+				     guint np, 
+				     guint niter,
+				     GtsFunc step_info,
+				     gpointer data)
+{
+  GSList * list = NULL, * seeds = NULL;
+  GtsGNode * seed = NULL;
+  guint min = G_MAXINT/2 - 1;
+  gpointer info[3];
+  GtsGraph * g1;
+  gboolean changed = TRUE;
+
+  g_return_val_if_fail (g != NULL, NULL);
+  g_return_val_if_fail (np > 0, NULL);
+
+  info[0] = &seed;
+  info[1] = g;
+  info[2] = &min;
+  gts_container_foreach (GTS_CONTAINER (g), 
+			 (GtsFunc) find_smallest_degree,
+			 info);
+  if (seed == NULL)
+    return NULL;
+
+  g1 = GTS_GRAPH (gts_object_new (GTS_OBJECT (g)->klass));
+  gts_container_add (GTS_CONTAINER (g1), GTS_CONTAINEE (seed));
+  list = g_slist_prepend (list, g1);
+  GTS_OBJECT (g1)->reserved = seed;
+  seeds = g_slist_prepend (seeds, seed);
+
+  while (--np && seed)
+    if ((seed = gts_graph_farthest (g, seeds))) {
+      g1 = GTS_GRAPH (gts_object_new (GTS_OBJECT (g)->klass));
+      gts_container_add (GTS_CONTAINER (g1), GTS_CONTAINEE (seed));
+      list = g_slist_prepend (list, g1);
+      GTS_OBJECT (g1)->reserved = seed;
+      seeds = g_slist_prepend (seeds, seed);
+    }
+  g_slist_free (seeds);
+  
+  partition_update (list, g);
+
+  while (changed && niter--) {
+    GSList * i;
+
+    changed = FALSE;
+    i = list;
+    while (i) {
+      GtsGraph * g1 = i->data;
+      GtsGNode * seed = GTS_OBJECT (g1)->reserved;
+      GtsGNode * new_seed = graph_new_seed (g1, seed);
+      if (new_seed != seed) {
+	changed = TRUE;
+	GTS_OBJECT (g1)->reserved = new_seed;
+      }
+      i = i->next;
+    }
+
+    if (changed) {
+      i = list;
+      while (i) {
+	GtsGraph * g1 = i->data;
+	GtsGNode * seed = GTS_OBJECT (g1)->reserved;
+
+	gts_object_destroy (GTS_OBJECT (g1));
+	i->data = g1 = GTS_GRAPH (gts_object_new (GTS_OBJECT (g)->klass));
+	gts_container_add (GTS_CONTAINER (g1), GTS_CONTAINEE (seed));
+	GTS_OBJECT (g1)->reserved = seed;
+	i = i->next;
+      }
+      partition_update (list, g);
+      if (step_info)
+	(* step_info) (list, data);
+    }
+  }
+  g_slist_foreach (list, (GFunc) gts_object_reset_reserved, NULL);
+  return list;
+}
+
+/* Graph bisection */
+
+static gdouble node_cost (GtsGNode * n, gpointer * data)
+{
+  GtsGraph * g = data[0];
+  GtsGraph * g1 = data[1];
+  GSList * i = GTS_SLIST_CONTAINER (n)->items;
+  gdouble cost = 0.;
+
+  while (i) {
+    GtsGEdge * e = i->data;
+    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, e);
+
+    if (gts_containee_is_contained (GTS_CONTAINEE (n1), GTS_CONTAINER (g))) {
+      if (gts_containee_is_contained (GTS_CONTAINEE (n1), GTS_CONTAINER (g1)))
+	cost -= gts_gedge_weight (e);
+      else 
+	cost += gts_gedge_weight (e);
+    }
+    i = i->next;
+  }
+
+  return cost;
+}
+
+static void add_neighbor (GtsGNode * n, GtsEHeap * heap)
+{
+  if (GTS_OBJECT (n)->reserved == n)
+    return;
+  if (GTS_OBJECT (n)->reserved)
+    gts_eheap_remove (heap, GTS_OBJECT (n)->reserved);
+  GTS_OBJECT (n)->reserved = gts_eheap_insert (heap, n);
+}
+
+static void add_unused (GtsGNode * n, GtsGraph * g2)
+{
+  if (GTS_OBJECT (n)->reserved)
+    GTS_OBJECT (n)->reserved = NULL;
+  else
+    gts_container_add (GTS_CONTAINER (g2), GTS_CONTAINEE (n));
+}
+
+static gdouble degree_cost (GtsGNode * n, GtsGraph * g)
+{
+  return gts_gnode_degree (n, g); 
+}
+
+static void add_seed (GtsGNode * n, GtsEHeap * heap)
+{
+  gts_eheap_insert (heap, n);
+}
+
+static void boundary_node1 (GtsGNode * n, GtsGraphBisection * bg)
+{
+  GSList * i = GTS_SLIST_CONTAINER (n)->items;
+
+  while (i) {
+    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
+    if (gts_containee_is_contained (GTS_CONTAINEE (n1), 
+				    GTS_CONTAINER (bg->g2))) {
+      g_hash_table_insert (bg->bg1, n, n1);
+      return;
+    }
+    i = i->next;
+  }
+}
+
+static void boundary_node2 (GtsGNode * n, GtsGraphBisection * bg)
+{
+  GSList * i = GTS_SLIST_CONTAINER (n)->items;
+
+  while (i) {
+    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
+    if (gts_containee_is_contained (GTS_CONTAINEE (n1), 
+				    GTS_CONTAINER (bg->g1))) {
+      g_hash_table_insert (bg->bg2, n, n1);
+      return;
+    }
+    i = i->next;
+  }
+}
+
+static void check_bg (GtsGNode * n, gpointer * data)
+{
+  GHashTable * bg = data[0];
+  GtsGraph * g = data[1];
+  gboolean * ok = data[2];
+  guint * nb = data[3];
+  guint nn = gts_gnode_degree (n, g);
+
+  if (nn > 0)
+    (*nb)++;
+  if ((nn > 0 && !g_hash_table_lookup (bg, n)) ||
+      (nn == 0 && g_hash_table_lookup (bg, n))) {
+    g_warning ("nn: %d lookup: %p\n",
+	       nn, g_hash_table_lookup (bg, n));
+    *ok = FALSE;
+  }
+}
+
+/**
+ * gts_graph_bisection_check:
+ * @bg: a #GtsGraphBisection.
+ *
+ * Checks that the boundary of @bg is correctly defined (used for
+ * debugging purposes).
+ *
+ * Returns: %TRUE if @bg is ok, %FALSE otherwise.  
+ */
+gboolean gts_graph_bisection_check (GtsGraphBisection * bg)
+{
+  gboolean ok = TRUE;
+  guint nb;
+  gpointer data[4];
+
+  g_return_val_if_fail (bg != NULL, FALSE);
+
+  nb = 0;
+  data[0] = bg->bg1;
+  data[1] = bg->g2;
+  data[2] = &ok;
+  data[3] = &nb;
+  gts_container_foreach (GTS_CONTAINER (bg->g1), (GtsFunc) check_bg, data);
+  g_return_val_if_fail (g_hash_table_size (bg->bg1) == nb, FALSE);
+
+  nb = 0;
+  data[0] = bg->bg2;
+  data[1] = bg->g1;
+  gts_container_foreach (GTS_CONTAINER (bg->g2), (GtsFunc) check_bg, data);
+  g_return_val_if_fail (g_hash_table_size (bg->bg2) == nb, FALSE);
+
+  return ok;
+}
+
+/**
+ * gts_graph_ggg_bisection:
+ * @g: a #GtsGraph.
+ * @ntry: the number of randomly selected initial seeds.
+ *
+ * An implementation of the "Greedy Graph Growing" algorithm of
+ * Karypis and Kumar (1997).  
+ *
+ * @ntry randomly chosen seeds are used and the best partition is retained.
+ *
+ * Returns: a new #GtsGraphBisection of @g.
+ */
+GtsGraphBisection * gts_graph_ggg_bisection (GtsGraph * g, guint ntry)
+{
+  gfloat size, bestcost = G_MAXFLOAT, smin;
+  GtsGraph * bestg1 = NULL, * bestg2 = NULL;
+  gboolean balanced = FALSE;
+  GtsEHeap * degree_heap;
+  GtsGNode * seed;
+  GtsGraphBisection * bg;
+
+  g_return_val_if_fail (g != NULL, NULL);
+
+  bg = g_malloc (sizeof (GtsGraphBisection));
+  bg->g = g;
+
+  size = gts_graph_weight (g)/2.;
+  smin = 0.9*size;
+
+  degree_heap = gts_eheap_new ((GtsKeyFunc) degree_cost, g);
+  gts_eheap_freeze (degree_heap);
+  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) add_seed, degree_heap);
+  gts_eheap_thaw (degree_heap);
+
+  while (ntry && ((seed = gts_eheap_remove_top (degree_heap, NULL)))) {
+    GtsGraph * g1, * g2;
+    GtsGNode * n;
+    gdouble cost;
+    gpointer data[2];
+    GtsEHeap * heap;
+  
+    g1 = gts_graph_new (GTS_GRAPH_CLASS (GTS_OBJECT (g)->klass),
+			g->node_class, g->edge_class);
+    g2 = gts_graph_new (GTS_GRAPH_CLASS (GTS_OBJECT (g)->klass),
+			g->node_class, g->edge_class);
+    
+    data[0] = g;
+    data[1] = g1;
+    heap = gts_eheap_new ((GtsKeyFunc) node_cost, data);
+
+    gts_container_add (GTS_CONTAINER (g1), GTS_CONTAINEE (seed));
+    GTS_OBJECT (seed)->reserved = seed;
+    gts_gnode_foreach_neighbor (seed, g, (GtsFunc) add_neighbor, heap);
+
+    while ((n = gts_eheap_remove_top (heap, &cost)))
+      if (gts_graph_weight (g1) + gts_gnode_weight (n) <= size) {
+	gts_container_add (GTS_CONTAINER (g1), GTS_CONTAINEE (n));
+	GTS_OBJECT (n)->reserved = n;
+	gts_gnode_foreach_neighbor (n, g, (GtsFunc) add_neighbor, heap);
+      }
+      else
+	GTS_OBJECT (n)->reserved = NULL;
+    gts_eheap_destroy (heap);
+    
+    gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) add_unused, g2);
+
+    cost = gts_graph_edges_cut_weight (g1);
+    if (!bestg1 || 
+	(!balanced && gts_graph_weight (g1) >= smin) ||
+	(cost < bestcost && gts_graph_weight (g1) >= smin)) {
+      if (bestg1)
+	bestcost = cost;
+      if (bestg1)
+	gts_object_destroy (GTS_OBJECT (bestg1));
+      if (bestg2)
+	gts_object_destroy (GTS_OBJECT (bestg2));
+      bestg1 = g1;
+      bestg2 = g2;
+      if (gts_graph_weight (g1) >= smin)
+	balanced = TRUE;
+    }
+    else {
+      gts_object_destroy (GTS_OBJECT (g1));
+      gts_object_destroy (GTS_OBJECT (g2));
+    }
+
+    ntry--;
+  }
+  gts_eheap_destroy (degree_heap);
+
+#ifdef DEBUG
+  fprintf (stderr, "bestcost: %5g g1: %5g|%5d g2: %5g|%5d\n",
+	   bestcost, 
+	   gts_graph_weight (bestg1), 
+	   gts_container_size (GTS_CONTAINER (bestg1)),
+	   gts_graph_weight (bestg2), 
+	   gts_container_size (GTS_CONTAINER (bestg2)));
+#endif
+
+  g_assert (bestg1 != NULL);
+  bg->g1 = bestg1;
+  g_assert (bestg2 != NULL);
+  bg->g2 = bestg2;
+  
+  /* boundary nodes */
+  bg->bg1 = g_hash_table_new (NULL, NULL);
+  gts_container_foreach (GTS_CONTAINER (bg->g1), (GtsFunc) boundary_node1, bg);
+  bg->bg2 = g_hash_table_new (NULL, NULL);
+  gts_container_foreach (GTS_CONTAINER (bg->g2), (GtsFunc) boundary_node2, bg);
+
+  return bg;
+}
+
+/**
+ * gts_graph_bfgg_bisection:
+ * @g: a #GtsGraph.
+ * @ntry: the number of randomly selected initial seeds.
+ *
+ * An implementation of a "Breadth-First Graph Growing" algorithm.
+ *
+ * @ntry randomly chosen seeds are used and the best partition is retained.
+ *
+ * Returns: a new #GtsGraphBisection of @g.
+ */
+GtsGraphBisection * gts_graph_bfgg_bisection (GtsGraph * g, guint ntry)
+{
+  gfloat size, bestcost = G_MAXFLOAT, smin;
+  GtsGraph * bestg1 = NULL, * bestg2 = NULL;
+  GtsEHeap * degree_heap;
+  GtsGNode * seed;
+  GtsGraphBisection * bg;
+
+  g_return_val_if_fail (g != NULL, NULL);
+
+  bg = g_malloc (sizeof (GtsGraphBisection));
+  bg->g = g;
+
+  size = gts_graph_weight (g)/2.;
+  smin = 0.9*size;
+
+  degree_heap = gts_eheap_new ((GtsKeyFunc) degree_cost, g);
+  gts_eheap_freeze (degree_heap);
+  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) add_seed, degree_heap);
+  gts_eheap_thaw (degree_heap);
+
+  while (ntry && ((seed = gts_eheap_remove_top (degree_heap, NULL)))) {
+    GtsGraph * g1, * g2;
+    GtsGNode * n;
+    gdouble cost;
+    GtsGraphTraverse * t = gts_graph_traverse_new (g, seed, 
+						   GTS_BREADTH_FIRST, TRUE);
+    
+    g1 = gts_graph_new (GTS_GRAPH_CLASS (GTS_OBJECT (g)->klass),
+			g->node_class, g->edge_class);
+    g2 = gts_graph_new (GTS_GRAPH_CLASS (GTS_OBJECT (g)->klass),
+			g->node_class, g->edge_class);
+
+    while ((n = gts_graph_traverse_next (t)))
+      if (gts_graph_weight (g1) + gts_gnode_weight (n) <= size) {
+	gts_container_add (GTS_CONTAINER (g1), GTS_CONTAINEE (n));
+	GTS_OBJECT (n)->reserved = n;
+      }
+    gts_graph_traverse_destroy (t);
+    
+    gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) add_unused, g2);
+
+    cost = gts_graph_edges_cut_weight (g1);
+    if (!bestg1 || (cost < bestcost && gts_graph_weight (g1) >= smin)) {
+      if (bestg1)
+	bestcost = cost;
+      if (bestg1)
+	gts_object_destroy (GTS_OBJECT (bestg1));
+      if (bestg2)
+	gts_object_destroy (GTS_OBJECT (bestg2));
+      bestg1 = g1;
+      bestg2 = g2;
+    }
+    else {
+      gts_object_destroy (GTS_OBJECT (g1));
+      gts_object_destroy (GTS_OBJECT (g2));
+    }
+
+    ntry--;
+  }
+  gts_eheap_destroy (degree_heap);
+
+#ifdef DEBUG
+  fprintf (stderr, "bestcost: %5g g1: %5g|%5d g2: %5g|%5d\n",
+	   bestcost, 
+	   gts_graph_weight (bestg1), 
+	   gts_container_size (GTS_CONTAINER (bestg1)),
+	   gts_graph_weight (bestg2), 
+	   gts_container_size (GTS_CONTAINER (bestg2)));
+#endif
+
+  bg->g1 = bestg1;
+  bg->g2 = bestg2;
+  
+  /* boundary nodes */
+  bg->bg1 = g_hash_table_new (NULL, NULL);
+  gts_container_foreach (GTS_CONTAINER (bg->g1), (GtsFunc) boundary_node1, bg);
+  bg->bg2 = g_hash_table_new (NULL, NULL);
+  gts_container_foreach (GTS_CONTAINER (bg->g2), (GtsFunc) boundary_node2, bg);
+
+  return bg;
+}
+
+static gdouble node_move_cost1 (GtsGNode * n, GtsGraphBisection * bg)
+{
+  return gts_gnode_move_cost (n, bg->g1, bg->g2);
+}
+
+static gdouble node_move_cost2 (GtsGNode * n, GtsGraphBisection * bg)
+{
+  return gts_gnode_move_cost (n, bg->g2, bg->g1);
+}
+
+static void build_heap (GtsGNode * n, GtsEHeap * heap)
+{
+  GTS_OBJECT (n)->reserved = gts_eheap_insert (heap, n);
+}
+
+/**
+ * gts_graph_bisection_kl_refine:
+ * @bg: a #GtsGraphBisection.
+ * @mmax: the maximum number of unsuccessful successive moves.
+ *
+ * An implementation of the simplified Kernighan-Lin algorithm for
+ * graph bisection refinement as described in Karypis and Kumar
+ * (1997).
+ *
+ * The algorithm stops if @mmax consecutive modes do not lead to a
+ * decrease in the number of edges cut. This last @mmax moves are
+ * undone.
+ *
+ * Returns: the decrease in the weight of the edges cut by the bisection.  
+ */
+gdouble gts_graph_bisection_kl_refine (GtsGraphBisection * bg,
+				       guint mmax)
+{
+  GtsEHeap * h1, * h2;
+  GtsGNode * n;
+  guint nm = 0, i;
+  GtsGNode ** moves;
+  gdouble bestcost = 0., totalcost = 0., best_balance;
+
+  g_return_val_if_fail (bg != NULL, 0.);
+  g_return_val_if_fail (mmax > 0, 0.);
+
+  h1 = gts_eheap_new ((GtsKeyFunc) node_move_cost1, bg);
+  gts_eheap_freeze (h1);
+  gts_container_foreach (GTS_CONTAINER (bg->g1), (GtsFunc) build_heap, h1);
+  gts_eheap_thaw (h1);
+
+  h2 = gts_eheap_new ((GtsKeyFunc) node_move_cost2, bg);
+  gts_eheap_freeze (h2);
+  gts_container_foreach (GTS_CONTAINER (bg->g2), (GtsFunc) build_heap, h2);
+  gts_eheap_thaw (h2);
+
+  moves = g_malloc (sizeof (GtsGNode *)*mmax);
+  best_balance = fabs (gts_graph_weight (bg->g1) - gts_graph_weight (bg->g2));
+
+  do {
+    GtsGraph * g1, * g2;
+    gdouble cost;
+
+    if (gts_graph_weight (bg->g1) > gts_graph_weight (bg->g2)) {
+      n = gts_eheap_remove_top (h1, &cost);
+      g1 = bg->g1;
+      g2 = bg->g2;
+    }
+    else {
+      n = gts_eheap_remove_top (h2, &cost);
+      g1 = bg->g2;
+      g2 = bg->g1;
+    }
+    if (n) {
+      GSList * i;
+
+      GTS_OBJECT (n)->reserved = NULL;
+      gts_container_add (GTS_CONTAINER (g2), GTS_CONTAINEE (n));
+      gts_container_remove (GTS_CONTAINER (g1), GTS_CONTAINEE (n));
+
+      totalcost += cost;
+      if (totalcost < bestcost) {
+	bestcost = totalcost;
+	nm = 0;
+      }
+      else if (totalcost == bestcost) {
+	gdouble balance = fabs (gts_graph_weight (g1) - gts_graph_weight (g2));
+
+	if (balance < best_balance) {
+	  best_balance = balance;
+	  nm = 0;
+	}
+      }	       
+      else
+	moves[nm++] = n;
+
+      i = GTS_SLIST_CONTAINER (n)->items;
+      while (i) {
+	GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
+	if (GTS_OBJECT (n1)->reserved && 
+	    gts_containee_is_contained (GTS_CONTAINEE (n1), 
+					GTS_CONTAINER (bg->g))) {
+	  GtsEHeap * h = 
+	    gts_containee_is_contained (GTS_CONTAINEE (n1), 
+					GTS_CONTAINER (bg->g1)) ? h1 : h2;
+	  gts_eheap_remove (h, GTS_OBJECT (n1)->reserved);
+	  GTS_OBJECT (n1)->reserved = gts_eheap_insert (h, n1);
+	}
+	i = i->next;
+      }
+    }
+  } while (n && nm < mmax);
+
+  gts_eheap_foreach (h1, (GFunc) gts_object_reset_reserved, NULL);
+  gts_eheap_foreach (h2, (GFunc) gts_object_reset_reserved, NULL);
+  gts_eheap_destroy (h1);
+  gts_eheap_destroy (h2);
+
+  /* undo last nm moves */
+  for (i = 0; i < nm; i++) {
+    GtsGNode * n = moves[i];
+    GtsGraph * g1 = 
+      gts_containee_is_contained (GTS_CONTAINEE (n),
+				  GTS_CONTAINER (bg->g1)) ? bg->g1 : bg->g2;
+    GtsGraph * g2 = g1 == bg->g1 ? bg->g2 : bg->g1;
+    
+    gts_container_add (GTS_CONTAINER (g2), GTS_CONTAINEE (n));
+    gts_container_remove (GTS_CONTAINER (g1), GTS_CONTAINEE (n));
+  }
+  g_free (moves);
+
+  return bestcost;
+}
+
+static void build_bheap (GtsGNode * n, GtsGNode * n1, GtsEHeap * heap)
+{
+  GTS_OBJECT (n)->reserved = gts_eheap_insert (heap, n);
+}
+
+static void update_neighbors (GtsGNode * n, GtsGraphBisection * bg,
+			      GtsEHeap * h1, GtsEHeap * h2)
+{
+  GSList * i;
+
+  i = GTS_SLIST_CONTAINER (n)->items;
+  while (i) {
+    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
+    if (gts_containee_is_contained (GTS_CONTAINEE (n1), 
+				    GTS_CONTAINER (bg->g))) {
+      GtsEHeap * h;
+      GtsGraph * g1, * g2;
+      GHashTable * bg1;
+
+      if (gts_containee_is_contained (GTS_CONTAINEE (n1),
+				      GTS_CONTAINER (bg->g1))) {
+	h = h1;
+	g1 = bg->g1;
+	g2 = bg->g2;
+	bg1 = bg->bg1;
+      }
+      else {
+	h = h2;
+	g1 = bg->g2;
+	g2 = bg->g1;
+	bg1 = bg->bg2;
+      }
+      g_hash_table_remove (bg1, n1);
+      if (h && GTS_OBJECT (n1)->reserved && GTS_OBJECT (n1)->reserved != n1) {
+	gts_eheap_remove (h, GTS_OBJECT (n1)->reserved);
+	GTS_OBJECT (n1)->reserved = NULL;
+      }
+      if (gts_gnode_degree (n1, g2)) {
+	g_hash_table_insert (bg1, n1, n1);
+	if (h && GTS_OBJECT (n1)->reserved != n1)
+	  GTS_OBJECT (n1)->reserved = gts_eheap_insert (h, n1);
+      }
+    }
+    i = i->next;
+  }  
+}
+
+/**
+ * gts_graph_bisection_bkl_refine:
+ * @bg: a #GtsGraphBisection.
+ * @mmax: the maximum number of unsuccessful successive moves.
+ * @imbalance: the maximum relative imbalance allowed between the
+ * weights of both halves of the partition.
+ *
+ * An implementation of the simplified boundary Kernighan-Lin
+ * algorithm for graph bisection refinement as described in Karypis
+ * and Kumar (1997).
+ *
+ * The algorithm stops if @mmax consecutive modes do not lead to a
+ * decrease in the number of edges cut. This last @mmax moves are
+ * undone.
+ *
+ * Returns: the decrease in the weight of the edges cut by the bisection.  
+ */
+gdouble gts_graph_bisection_bkl_refine (GtsGraphBisection * bg,
+					guint mmax,
+					gfloat imbalance)
+{
+  GtsEHeap * h1, * h2;
+  GtsGNode * n;
+  guint nm = 0, i;
+  GtsGNode ** moves;
+  gdouble bestcost = 0., totalcost = 0., best_balance;
+  gboolean balanced = FALSE;
+
+  g_return_val_if_fail (bg != NULL, 0.);
+  g_return_val_if_fail (mmax > 0, 0.);
+  g_return_val_if_fail (imbalance >= 0. && imbalance <= 1., 0.);
+
+  h1 = gts_eheap_new ((GtsKeyFunc) node_move_cost1, bg);
+  gts_eheap_freeze (h1);
+  g_hash_table_foreach (bg->bg1, (GHFunc) build_bheap, h1);
+  gts_eheap_thaw (h1);
+
+  h2 = gts_eheap_new ((GtsKeyFunc) node_move_cost2, bg);
+  gts_eheap_freeze (h2);
+  g_hash_table_foreach (bg->bg2, (GHFunc) build_bheap, h2);
+  gts_eheap_thaw (h2);
+
+  moves = g_malloc (sizeof (GtsGNode *)*mmax);
+  imbalance *= gts_graph_weight (bg->g);
+  best_balance = fabs (gts_graph_weight (bg->g1) - gts_graph_weight (bg->g2));
+  if (best_balance <= imbalance)
+    balanced = TRUE;
+
+  do {
+    GtsGraph * g1, * g2;
+    GHashTable * bg1, * bg2;
+    gdouble cost;
+
+    if (gts_graph_weight (bg->g1) > gts_graph_weight (bg->g2)) {
+      n = gts_eheap_remove_top (h1, &cost);
+      g1 = bg->g1;
+      g2 = bg->g2;
+      bg1 = bg->bg1;
+      bg2 = bg->bg2;
+    }
+    else {
+      n = gts_eheap_remove_top (h2, &cost);
+      g1 = bg->g2;
+      g2 = bg->g1;
+      bg1 = bg->bg2;
+      bg2 = bg->bg1;
+    }
+    if (n) {
+      gdouble balance;
+	
+      GTS_OBJECT (n)->reserved = n;
+      gts_container_add (GTS_CONTAINER (g2), GTS_CONTAINEE (n));
+      gts_container_remove (GTS_CONTAINER (g1), GTS_CONTAINEE (n));
+      g_hash_table_remove (bg1, n);
+      if (gts_gnode_degree (n, g1))
+	g_hash_table_insert (bg2, n, n);
+
+      update_neighbors (n, bg, h1, h2);
+
+      totalcost += cost;
+      balance = fabs (gts_graph_weight (g1) - gts_graph_weight (g2));
+      
+      if (!balanced && balance <= imbalance) {
+	bestcost = totalcost;
+	best_balance = balance;
+	balanced = TRUE;
+	nm = 0;
+      }
+      else if (totalcost < bestcost && 
+	       (balance < best_balance || balance <= imbalance)) {
+	bestcost = totalcost;
+	best_balance = balance;
+	nm = 0;
+      }
+      else if (totalcost == bestcost && balance < best_balance) {
+	best_balance = balance;
+	nm = 0;
+      }
+      else
+	moves[nm++] = n;
+    }
+  } while (n && nm < mmax);
+
+  gts_container_foreach (GTS_CONTAINER (bg->g), 
+			 (GtsFunc) gts_object_reset_reserved, NULL);
+  gts_eheap_destroy (h1);
+  gts_eheap_destroy (h2);
+
+  /* undo last nm moves */
+  for (i = 0; i < nm; i++) {
+    GtsGNode * n = moves[i];
+    GtsGraph * g1, * g2;
+    GHashTable * bg1, * bg2;
+
+    if (gts_containee_is_contained (GTS_CONTAINEE (n),
+				    GTS_CONTAINER (bg->g1))) {
+      g1 = bg->g1;
+      g2 = bg->g2;
+      bg1 = bg->bg1;
+      bg2 = bg->bg2;
+    }
+    else {
+      g1 = bg->g2;
+      g2 = bg->g1;
+      bg1 = bg->bg2;
+      bg2 = bg->bg1;
+    }
+    
+    gts_container_add (GTS_CONTAINER (g2), GTS_CONTAINEE (n));
+    gts_container_remove (GTS_CONTAINER (g1), GTS_CONTAINEE (n));
+    g_hash_table_remove (bg1, n);
+    if (gts_gnode_degree (n, g1))
+      g_hash_table_insert (bg2, n, n);
+
+    update_neighbors (n, bg, NULL, NULL);
+  }
+  g_free (moves);
+
+  return bestcost;
+}
+
+/* Multilevel partitioning */
+
+static void bisection_children (GtsGNodeSplit * ns, GtsGraphBisection * bg)
+{
+  GtsGraph * g, * g1;
+  GHashTable * bbg;
+  GtsGNode * n1 = GTS_GNODE_SPLIT_N1 (ns);
+  GtsGNode * n2 = GTS_GNODE_SPLIT_N2 (ns);
+
+  if (gts_containee_is_contained (GTS_CONTAINEE (ns->n),
+				  GTS_CONTAINER (bg->g1))) {
+    g = bg->g1;
+    g1 = bg->g2;
+    bbg = bg->bg1;
+  }
+  else {
+    g = bg->g2;
+    g1 = bg->g1;
+    bbg = bg->bg2;
+  }
+
+  gts_allow_floating_gnodes = TRUE;
+  gts_container_remove (GTS_CONTAINER (g), GTS_CONTAINEE (ns->n));
+  gts_allow_floating_gnodes = FALSE;
+  gts_container_add (GTS_CONTAINER (g), GTS_CONTAINEE (n1));
+  gts_container_add (GTS_CONTAINER (g), GTS_CONTAINEE (n2));
+
+  if (g_hash_table_lookup (bbg, ns->n)) {
+    g_hash_table_remove (bbg, ns->n);
+    if (gts_gnode_degree (n1, g1) > 0)
+      g_hash_table_insert (bbg, n1, n1);
+    if (gts_gnode_degree (n2, g1) > 0)
+      g_hash_table_insert (bbg, n2, n2);
+  }
+}
+
+/**
+ * gts_graph_bisection_new:
+ * @wg: a #GtsWGraph.
+ * @ntry: the number of tries for the graph growing algorithm.
+ * @mmax: the number of unsucessful moves for the refinement algorithm.
+ * @nmin: the minimum number of nodes of the coarsest graph.
+ * @imbalance: the maximum relative imbalance allowed between the
+ * weights of both halves of the partition.
+ *
+ * An implementation of a multilevel bisection algorithm as presented
+ * in Karypis and Kumar (1997). A multilevel hierarchy of graphs is
+ * created using the #GtsPGraph object. The bisection of the coarsest
+ * graph is created using the gts_graph_ggg_bisection() function. The
+ * graph is then uncoarsened using gts_pgraph_down() and at each level
+ * the bisection is refined using gts_graph_bisection_bkl_refine().
+ *
+ * Returns: a new #GtsGraphBisection of @wg.  
+ */
+GtsGraphBisection * gts_graph_bisection_new (GtsWGraph * wg,
+					     guint ntry,
+					     guint mmax,
+					     guint nmin,
+					     gfloat imbalance)
+{
+  GtsGraph * g;
+  GtsPGraph * pg;
+  GtsGraphBisection * bg;
+  gdouble cost;
+
+  g_return_val_if_fail (wg != NULL, NULL);
+
+  g = GTS_GRAPH (wg);
+  pg = gts_pgraph_new (gts_pgraph_class (), g, 
+		       gts_gnode_split_class (),
+		       gts_wgnode_class (),
+		       gts_wgedge_class (),
+		       nmin);
+
+  bg = gts_graph_ggg_bisection (g, ntry);
+#ifdef DEBUG
+  fprintf (stderr, "before size: %5d weight: %5g cuts: %5d cweight: %5g\n",
+	   gts_container_size (GTS_CONTAINER (bg->g1)),
+	   gts_graph_weight (bg->g1),
+	   gts_graph_edges_cut (bg->g1),
+	   gts_graph_edges_cut_weight (bg->g1));
+  g_assert (gts_graph_bisection_check (bg));
+#endif
+  while ((cost = gts_graph_bisection_bkl_refine (bg, mmax, imbalance))) {
+#ifdef DEBUG
+    fprintf (stderr, "  cost: %g\n", cost);
+    g_assert (gts_graph_bisection_check (bg));
+#endif
+  }
+#ifdef DEBUG
+  fprintf (stderr, "after  size: %5d weight: %5g cuts: %5d cweight: %5g\n",
+	   gts_container_size (GTS_CONTAINER (bg->g1)),
+	   gts_graph_weight (bg->g1),
+	   gts_graph_edges_cut (bg->g1),
+	   gts_graph_edges_cut_weight (bg->g1));
+#endif
+  while (gts_pgraph_down (pg, (GtsFunc) bisection_children, bg)) {
+#ifdef DEBUG
+    fprintf (stderr, "before size: %5d weight: %5g cuts: %5d cweight: %5g\n",
+	     gts_container_size (GTS_CONTAINER (bg->g1)),
+	     gts_graph_weight (bg->g1),
+	     gts_graph_edges_cut (bg->g1),
+	     gts_graph_edges_cut_weight (bg->g1));	   
+#endif
+    while ((cost = gts_graph_bisection_bkl_refine (bg, mmax, imbalance))) {
+#ifdef DEBUG
+      fprintf (stderr, "  cost: %g\n", cost);
+      g_assert (gts_graph_bisection_check (bg));
+#endif
+    }
+#ifdef DEBUG
+    fprintf (stderr, "after  size: %5d weight: %5g cuts: %5d cweight: %5g\n",
+	     gts_container_size (GTS_CONTAINER (bg->g1)),
+	     gts_graph_weight (bg->g1),
+	     gts_graph_edges_cut (bg->g1),
+	     gts_graph_edges_cut_weight (bg->g1));
+#endif
+  }
+  gts_object_destroy (GTS_OBJECT (pg));
+
+  return bg;
+}
+
+/**
+ * gts_graph_bisection_destroy:
+ * @bg: a #GtsGraphBisection.
+ * @destroy_graphs: controls graph destruction.
+ *
+ * Frees all the memory allocated for @bg. If @destroy_graphs is %TRUE
+ * the graphs created by @bg are destroyed.  
+ */
+void gts_graph_bisection_destroy (GtsGraphBisection * bg,
+				  gboolean destroy_graphs)
+{
+  g_return_if_fail (bg != NULL);
+
+  g_hash_table_destroy (bg->bg1);
+  g_hash_table_destroy (bg->bg2);
+
+  if (destroy_graphs) {
+    gts_object_destroy (GTS_OBJECT (bg->g1));
+    gts_object_destroy (GTS_OBJECT (bg->g2));
+  }
+
+  g_free (bg);
+}
+
+static void recursive_bisection (GtsWGraph * wg,
+				 guint np,
+				 guint ntry,
+				 guint mmax,
+				 guint nmin,
+				 gfloat imbalance,
+				 GSList ** list)
+{
+  if (np == 0)
+    *list = g_slist_prepend (*list, wg);
+  else {
+    GtsGraphBisection * bg = 
+      gts_graph_bisection_new (wg, ntry, mmax, nmin, imbalance);
+    GtsGraph * g1 = bg->g1;
+    GtsGraph * g2 = bg->g2;
+
+    gts_object_destroy (GTS_OBJECT (wg));
+    gts_graph_bisection_destroy (bg, FALSE);
+    recursive_bisection (GTS_WGRAPH (g1), np - 1, ntry, mmax, nmin, imbalance,
+			 list);
+    recursive_bisection (GTS_WGRAPH (g2), np - 1, ntry, mmax, nmin, imbalance,
+			 list);
+  }
+}
+
+/**
+ * gts_graph_recursive_bisection:
+ * @wg: a #GtsWGraph.
+ * @n: the number of bisection levels.
+ * @ntry: the number of tries for the graph growing algorithm.
+ * @mmax: the number of unsucessful moves for the refinement algorithm.
+ * @nmin: the minimum number of nodes of the coarsest graph.
+ * @imbalance: the maximum relative imbalance allowed between the
+ * weights of both halves of the partition.
+ *
+ * Calls gts_graph_bisection_new() recursively in order to obtain a
+ * 2^@n partition of @wg.
+ *
+ * Returns: a list of 2^@n new #GtsGraph representing the partition.
+ */
+GSList * gts_graph_recursive_bisection (GtsWGraph * wg,
+					guint n,
+					guint ntry,
+					guint mmax,
+					guint nmin,
+					gfloat imbalance)
+{
+  GtsGraphBisection * bg;
+  GtsGraph * g1, * g2;
+  GSList * list = NULL;
+
+  g_return_val_if_fail (wg != NULL, NULL);
+  g_return_val_if_fail (n > 0, NULL);
+  
+  bg = gts_graph_bisection_new (wg, ntry, mmax, nmin, imbalance);
+  g1 = bg->g1;
+  g2 = bg->g2;
+  gts_graph_bisection_destroy (bg, FALSE);
+  recursive_bisection (GTS_WGRAPH (g1), n - 1, ntry, mmax, nmin, imbalance, 
+		       &list);
+  recursive_bisection (GTS_WGRAPH (g2), n - 1, ntry, mmax, nmin, imbalance,
+		       &list);
+
+  return list;
+}
diff --git a/gts/pgraph.c b/gts/pgraph.c
new file mode 100644
index 0000000..6d1f619
--- /dev/null
+++ b/gts/pgraph.c
@@ -0,0 +1,584 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "gts.h"
+
+/* GtsGNodeSplit */
+
+static void gnode_split_destroy (GtsObject * object)
+{
+  GtsGNodeSplit * ns = GTS_GNODE_SPLIT (object);
+
+  if (gts_container_size (GTS_CONTAINER (ns->n)) == 0) {
+    g_assert (GTS_SLIST_CONTAINEE (ns->n)->containers == NULL);
+    gts_object_destroy (GTS_OBJECT (ns->n));
+  }
+  else {
+    /* GtsGNode * n1 = GTS_GNODE_SPLIT_N1 (ns); */
+    /* GtsGNode * n2 = GTS_GNODE_SPLIT_N2 (ns); */
+
+    g_warning ("Memory deallocation for GtsGNodeSplit not fully implemented yet: memory leak!");
+  }
+
+  (* GTS_OBJECT_CLASS (gts_gnode_split_class ())->parent_class->destroy) 
+    (object);
+}
+
+static void gnode_split_class_init (GtsGNodeSplitClass * klass)
+{
+  GTS_OBJECT_CLASS (klass)->destroy = gnode_split_destroy;
+}
+
+static void gnode_split_init (GtsGNodeSplit * ns)
+{
+  ns->n = NULL;
+  ns->n1 = ns->n2 = NULL;
+}
+
+/**
+ * gts_gnode_split_class:
+ *
+ * Returns: the #GtsGNodeSplitClass.
+ */
+GtsGNodeSplitClass * gts_gnode_split_class (void)
+{
+  static GtsGNodeSplitClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo gnode_split_info = {
+      "GtsGNodeSplit",
+      sizeof (GtsGNodeSplit),
+      sizeof (GtsGNodeSplitClass),
+      (GtsObjectClassInitFunc) gnode_split_class_init,
+      (GtsObjectInitFunc) gnode_split_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (gts_object_class (), &gnode_split_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_gnode_split_new:
+ * @klass: a #GtsGNodeSplitClass.
+ * @n: a #GtsGNode.
+ * @n1: a #GtsGNodeSplit or #GtsGNode.
+ * @n2: a #GtsGNodeSplit or #GtsGNode.
+ *
+ * Creates a new #GtsGNodeSplit which would collapse @n1 and @n2 into
+ * @n. The collapse itself is not performed.
+ *
+ * Returns: the new #GtsGNodeSplit.
+ */
+GtsGNodeSplit * gts_gnode_split_new (GtsGNodeSplitClass * klass,
+				     GtsGNode * n, 
+				     GtsObject * n1,
+				     GtsObject * n2)
+{
+  GtsGNodeSplit * ns;
+
+  g_return_val_if_fail (klass != NULL, NULL);
+  g_return_val_if_fail (n != NULL, NULL);
+  g_return_val_if_fail (GTS_IS_GNODE_SPLIT (n1) || GTS_IS_GNODE (n1), NULL);
+  g_return_val_if_fail (GTS_IS_GNODE_SPLIT (n2) || GTS_IS_GNODE (n2), NULL);
+
+  ns = GTS_GNODE_SPLIT (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  ns->n = n;
+  ns->n1 = n1;
+  ns->n2 = n2;
+
+  return ns;
+}
+
+static void connect_edge (GtsGEdge * e, gpointer * data)
+{
+  GtsGNode * n = data[0];
+  GtsGNode * n1 = data[1];
+  GtsGNode * n2 = data[2];
+
+  if (GTS_OBJECT (e)->reserved || /* edge is disconnected */
+      gts_gedge_connects (e, n1, n2))
+    return;
+  if (e->n1 == n1 || e->n1 == n2)
+    e->n1 = n;
+  else if (e->n2 == n1 || e->n2 == n2)
+    e->n2 = n;
+  else
+    g_assert_not_reached ();
+  gts_container_add (GTS_CONTAINER (n), GTS_CONTAINEE (e));
+}
+
+/**
+ * gts_gnode_split_collapse:
+ * @ns: a #GtsGNodeSplit.
+ * @g: a #GtsGraph.
+ * @klass: a #GtsWGEdgeClass.
+ *
+ * Collapses the node split @ns. Any new edge created during the
+ * process will be of class @klass.  
+ */
+void gts_gnode_split_collapse (GtsGNodeSplit * ns,
+			       GtsGraph * g,
+			       GtsWGEdgeClass * klass)
+{
+  GtsGNode * n1, * n2;
+  GSList * i;
+  gpointer data[3];
+
+  g_return_if_fail (ns != NULL);
+  g_return_if_fail (g != NULL);
+  g_return_if_fail (gts_container_size (GTS_CONTAINER (ns->n)) == 0);
+
+  n1 = GTS_GNODE_SPLIT_N1 (ns);
+  n2 = GTS_GNODE_SPLIT_N2 (ns);
+
+  /* look for triangles */
+  i = GTS_SLIST_CONTAINER (n1)->items;
+  while (i) {
+    GtsGEdge * e13 = i->data;
+    GtsGNode * n3 = GTS_GNODE_NEIGHBOR (n1, e13);
+    if (n3 != n2) {
+      GSList * j = GTS_SLIST_CONTAINER (n3)->items;
+      while (j) {
+	GtsGEdge * e32 = j->data;
+	GSList * next = j->next;
+	GtsGNode * n4 = GTS_GNODE_NEIGHBOR (n3, e32);
+	if (n4 == n2) { /* found triangle n1 (e13) n3 (e32) n2 */
+	  gts_wgedge_new (klass, ns->n, n3,
+			  gts_gedge_weight (e13) + gts_gedge_weight (e32));
+	  GTS_OBJECT (e13)->reserved = n3;
+	  GTS_OBJECT (e32)->reserved = n3;
+	  GTS_SLIST_CONTAINER (n3)->items = 
+	    g_slist_remove (GTS_SLIST_CONTAINER (n3)->items, e32);
+	}
+	j = next;
+      }
+      if (GTS_OBJECT (e13)->reserved == n3)
+	GTS_SLIST_CONTAINER (n3)->items = 
+	  g_slist_remove (GTS_SLIST_CONTAINER (n3)->items, e13);
+    }
+    i = i->next;
+  }
+
+  /* connect edges to new node */
+  data[0] = ns->n;
+  data[1] = n1;
+  data[2] = n2;
+  gts_container_foreach (GTS_CONTAINER (n1), (GtsFunc) connect_edge, data);
+  gts_container_foreach (GTS_CONTAINER (n2), (GtsFunc) connect_edge, data);
+
+  gts_allow_floating_gnodes = TRUE;
+  gts_container_remove (GTS_CONTAINER (g), GTS_CONTAINEE (n1));
+  gts_container_remove (GTS_CONTAINER (g), GTS_CONTAINEE (n2));
+  gts_allow_floating_gnodes = FALSE;
+  gts_container_add (GTS_CONTAINER (g), GTS_CONTAINEE (ns->n));
+}
+
+static void restore_edge (GtsGEdge * e, gpointer * data)
+{
+  GtsGNode * n = data[0];
+  GtsGNode * n1 = data[1];
+  GtsGNode * n2 = data[2];
+  GtsGNode * n3 = GTS_OBJECT (e)->reserved;
+
+  if (n3) { /* e is a disconnected edge */
+    GTS_OBJECT (e)->reserved = NULL;
+    gts_container_add (GTS_CONTAINER (n3), GTS_CONTAINEE (e));
+    return;
+  }
+
+  if (gts_gedge_connects (e, n1, n2))
+    return;
+
+  if (e->n1 == n)
+    e->n1 = n1;
+  else if (e->n2 == n)
+    e->n2 = n1;
+  else
+    g_assert_not_reached ();
+  GTS_SLIST_CONTAINER (n)->items = 
+    g_slist_remove (GTS_SLIST_CONTAINER (n)->items, e);
+}
+
+/**
+ * gts_gnode_split_expand:
+ * @ns: a #GtsGNodeSplit.
+ * @g: a #GtsGraph.
+ *
+ * Expands the node split ns adding the new nodes to @g.
+ */
+void gts_gnode_split_expand (GtsGNodeSplit * ns,
+			     GtsGraph * g)
+{
+  GtsGNode * n1, * n2;
+  gpointer data[3];
+  GSList * i;
+
+  g_return_if_fail (ns != NULL);
+  g_return_if_fail (g != NULL);
+  g_return_if_fail (gts_containee_is_contained (GTS_CONTAINEE (ns->n), 
+						GTS_CONTAINER (g)));
+
+  n1 = GTS_GNODE_SPLIT_N1 (ns);
+  n2 = GTS_GNODE_SPLIT_N2 (ns);
+
+  data[0] = ns->n;
+  data[1] = n1;
+  data[2] = n2;
+  gts_container_foreach (GTS_CONTAINER (n1), (GtsFunc) restore_edge, data);
+  data[1] = n2;
+  data[2] = n1;
+  gts_container_foreach (GTS_CONTAINER (n2), (GtsFunc) restore_edge, data);
+
+  i = GTS_SLIST_CONTAINER (ns->n)->items;
+  while (i) {
+    GSList * next = i->next;
+    gts_container_remove (GTS_CONTAINER (ns->n), GTS_CONTAINEE (i->data));
+    i = next;
+  }
+  g_assert (gts_container_size (GTS_CONTAINER (ns->n)) == 0);
+  
+  gts_allow_floating_gnodes = TRUE;
+  gts_container_remove (GTS_CONTAINER (g), GTS_CONTAINEE (ns->n));
+  gts_allow_floating_gnodes = FALSE;
+
+  gts_container_add (GTS_CONTAINER (g), GTS_CONTAINEE (n1));
+  gts_container_add (GTS_CONTAINER (g), GTS_CONTAINEE (n2));
+}
+
+/* GtsPGraph */
+
+static void pgraph_destroy (GtsObject * object)
+{
+  GtsPGraph * pg = GTS_PGRAPH (object);
+  guint i;
+
+  for (i = 0; i < pg->split->len; i++)
+    gts_object_destroy (GTS_OBJECT (g_ptr_array_index (pg->split, i)));
+  g_ptr_array_free (pg->split, TRUE);
+  g_array_free (pg->levels, TRUE);
+
+  (* GTS_OBJECT_CLASS (gts_pgraph_class ())->parent_class->destroy) (object);
+}
+
+static void pgraph_class_init (GtsPGraphClass * klass)
+{
+  GTS_OBJECT_CLASS (klass)->destroy = pgraph_destroy;
+}
+
+static void pgraph_init (GtsPGraph * pg)
+{
+  pg->g = NULL;
+  pg->split = g_ptr_array_new ();
+  pg->levels = g_array_new (FALSE, FALSE, sizeof (guint));
+  pg->level = 0;
+  pg->split_class = gts_gnode_split_class ();
+  pg->edge_class = gts_wgedge_class ();
+  pg->pos = pg->min = 0;
+}
+
+/**
+ * gts_pgraph_class:
+ *
+ * Returns: the #GtsPGraphClass.
+ */
+GtsPGraphClass * gts_pgraph_class (void)
+{
+  static GtsPGraphClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo pgraph_info = {
+      "GtsPGraph",
+      sizeof (GtsPGraph),
+      sizeof (GtsPGraphClass),
+      (GtsObjectClassInitFunc) pgraph_class_init,
+      (GtsObjectInitFunc) pgraph_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (gts_object_class (), &pgraph_info);
+  }
+
+  return klass;
+}
+
+static void match_neighbor (GtsGNode * n, gpointer * data)
+{
+  if (!GTS_OBJECT (n)->reserved) {
+    GtsGraph * g = data[0];
+    GSList ** list = data[1];
+    GSList * i = GTS_SLIST_CONTAINER (n)->items;
+    gfloat wmax = - G_MAXFLOAT;
+    GtsGEdge * emax = NULL;
+    
+    while (i) {
+      GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
+      if (!GTS_OBJECT (n1)->reserved &&
+	  gts_gedge_weight (i->data) > wmax &&
+	  gts_containee_is_contained (GTS_CONTAINEE (n1), GTS_CONTAINER (g))) {
+	emax = i->data;
+	wmax = gts_gedge_weight (emax);
+      }
+      i = i->next;
+    }
+    if (emax) {
+      GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, emax);
+
+      GTS_OBJECT (n1)->reserved = n;
+      GTS_OBJECT (n)->reserved = n1;
+      *list = g_slist_prepend (*list, emax);
+    }
+  }
+}
+
+static GSList * maximal_matching (GtsGraph * g)
+{
+  GSList * list = NULL;
+  gpointer data[2];
+
+  data[0] = g;
+  data[1] = &list;
+  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) match_neighbor, data);
+  gts_container_foreach (GTS_CONTAINER (g), 
+			 (GtsFunc) gts_object_reset_reserved,
+			 NULL);
+
+  return list;
+}
+
+/**
+ * gts_pgraph_new:
+ * @klass: a #GtsPGraphClass.
+ * @g: a #GtsGraph.
+ * @split_class: a #GtsGNodeSplitClass.
+ * @node_class: a #GtsWGNodeClass.
+ * @edge_class: a #GtsWGEdgeClass.
+ * @min: the minimum number of nodes.
+ *
+ * Creates a new multilevel approximation of graph @g. At each level a
+ * maximal matching is created using the Heavy Edge Matching (HEM)
+ * technique of Karypis and Kumar (1997). The newly created nodes are
+ * of type @node_class and their weight is set to the sum of the
+ * weights of their children. The newly created edges are of type
+ * @edge_class and their weight is set to the sum of the weight of the
+ * collapsed edges. The last level is reached when the maximal
+ * matching obtained would lead to a graph with less than @min nodes.
+ *
+ * Returns: the new #GtsPGraph containing the multilevel
+ * representation of @g.  
+ */
+GtsPGraph * gts_pgraph_new (GtsPGraphClass * klass,
+			    GtsGraph * g,
+			    GtsGNodeSplitClass * split_class,
+			    GtsWGNodeClass * node_class,
+			    GtsWGEdgeClass * edge_class,
+			    guint min)
+{
+  GtsPGraph * pg;
+  GSList * matching;
+
+  g_return_val_if_fail (klass != NULL, NULL);
+  g_return_val_if_fail (g != NULL, NULL);
+  g_return_val_if_fail (split_class != NULL, NULL);
+  g_return_val_if_fail (node_class != NULL, NULL);
+  g_return_val_if_fail (edge_class != NULL, NULL);
+
+  pg = GTS_PGRAPH (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  pg->g = g;
+  pg->split_class = split_class;
+  pg->edge_class = edge_class;
+
+  while (gts_container_size (GTS_CONTAINER (g)) > min &&
+	 (matching = maximal_matching (g))) {
+    GSList * i = matching;
+    guint size = gts_container_size (GTS_CONTAINER (g));
+
+    g_array_append_val (pg->levels, size);
+
+    while (i && gts_container_size (GTS_CONTAINER (g)) > min) {
+      GtsGEdge * e = i->data;
+      GtsGNode * n = GTS_GNODE (gts_wgnode_new (node_class,
+						gts_gnode_weight (e->n1) +
+						gts_gnode_weight (e->n2)));
+      GtsGNodeSplit * ns = gts_gnode_split_new (split_class, n,
+						GTS_OBJECT (e->n1),
+						GTS_OBJECT (e->n2));
+      gts_gnode_split_collapse (ns, g, edge_class);
+      g_ptr_array_add (pg->split, ns);
+      i = i->next;
+    }
+    g_slist_free (matching);
+  }
+
+  pg->pos = pg->split->len;
+  pg->min = gts_container_size (GTS_CONTAINER (g));
+  pg->level = pg->levels->len;
+  
+  return pg;
+}
+
+/**
+ * gts_pgraph_add_node:
+ * @pg: a #GtsPGraph.
+ *
+ * Adds one node to the multilevel graph @pg by expanding the next
+ * available #GtsGNodeSplit.
+ *
+ * Returns: the expanded #GtsGNodeSplit or #NULL if all the
+ * #GtsGNodeSplit have already been expanded.  
+ */
+GtsGNodeSplit * gts_pgraph_add_node (GtsPGraph * pg)
+{ 
+  GtsGNodeSplit * ns;
+
+  g_return_val_if_fail (pg != NULL, NULL);
+
+  if (pg->pos == 0)
+    return NULL;
+
+  ns = g_ptr_array_index (pg->split, --pg->pos);
+  gts_gnode_split_expand (ns, pg->g);
+
+  return ns;
+}
+
+/**
+ * gts_pgraph_remove_node:
+ * @pg: a #GtsPGraph.
+ *
+ * Removes one node from the multilevel graph @pg by collapsing the
+ * first available #GtsGNodeSplit.
+ *
+ * Returns: the collapsed #GtsGNodeSplit or %NULL if all the
+ * #GtsGNodeSplit have already been collapsed.  
+ */
+GtsGNodeSplit * gts_pgraph_remove_node (GtsPGraph * pg)
+{
+  GtsGNodeSplit * ns;
+
+  g_return_val_if_fail (pg != NULL, NULL);
+
+  if (pg->pos == pg->split->len)
+    return NULL;
+
+  ns = g_ptr_array_index (pg->split, pg->pos++);
+  gts_gnode_split_collapse (ns, pg->g, pg->edge_class);
+
+  return ns;
+}
+
+/**
+ * gts_pgraph_max_node_number:
+ * @pg: a #GtsPGraph.
+ *
+ * Returns: the maximum number of nodes of @pg i.e. the number of
+ * nodes if all the #GtsGNodeSplit were expanded.  
+ */
+guint gts_pgraph_max_node_number (GtsPGraph * pg)
+{
+  g_return_val_if_fail (pg != NULL, 0);
+
+  return pg->min + pg->split->len;
+}
+
+/**
+ * gts_pgraph_min_node_number:
+ * @pg: a #GtsPGraph.
+ *
+ * Returns: the minimum number of nodes of @pg i.e. the number of
+ * nodes if all the #GtsGNodeSplit were collapsed.  
+ */
+guint gts_pgraph_min_node_number (GtsPGraph * pg)
+{
+  g_return_val_if_fail (pg != NULL, 0);
+
+  return pg->min;
+}
+
+/**
+ * gts_pgraph_set_node_number:
+ * @pg: a #GtsPGraph.
+ * @n: a number of nodes.
+ *
+ * Performs the required number of collapses or expansions to set the
+ * number of nodes of @pg to @n.
+ */
+void gts_pgraph_set_node_number (GtsPGraph * pg, guint n)
+{
+  g_return_if_fail (pg != NULL);
+
+  n = pg->min + pg->split->len - n;
+  while (pg->pos > n && gts_pgraph_add_node (pg))
+    ;
+  while (pg->pos < n && gts_pgraph_remove_node (pg))
+    ;
+}
+
+/**
+ * gts_pgraph_get_node_number:
+ * @pg: a #GtsPGraph.
+ *
+ * Returns: the current number of nodes of @pg.
+ */
+guint gts_pgraph_get_node_number (GtsPGraph * pg)
+{
+  g_return_val_if_fail (pg != NULL, 0);
+  
+  return pg->min + pg->split->len - pg->pos;
+}
+
+/**
+ * gts_pgraph_down:
+ * @pg: a #GtsPGraph.
+ * @func: a #GtsFunc or %NULL.
+ * @data: user data to pass to @func.
+ *
+ * Performs the required number of expansions to go from the current
+ * level to the level immediately below.
+ *
+ * If @func is not %NULL, it is called after each #GtsGNodeSplit has
+ * been expanded.  
+ *
+ * Returns: %FALSE if it is not possible to go down one level, %TRUE
+ * otherwise.  
+ */
+gboolean gts_pgraph_down (GtsPGraph * pg,
+			  GtsFunc func,
+			  gpointer data)
+{
+  guint size;
+
+  g_return_val_if_fail (pg != NULL, FALSE);
+
+  if (pg->level == 0)
+    return FALSE;
+
+  size = g_array_index (pg->levels, guint, --(pg->level));
+  while (gts_container_size (GTS_CONTAINER (pg->g)) < size) {
+    GtsGNodeSplit * ns = gts_pgraph_add_node (pg);
+
+    g_assert (ns);
+    if (func)
+      (* func) (ns, data);
+  }
+  return TRUE;
+}
+
diff --git a/gts/point.c b/gts/point.c
new file mode 100644
index 0000000..42fce69
--- /dev/null
+++ b/gts/point.c
@@ -0,0 +1,986 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <math.h>
+#include <stdlib.h>
+#include "gts.h"
+#include "gts-private.h"
+#include "predicates.h"
+
+static void point_read (GtsObject ** o, GtsFile * f)
+{
+  GtsPoint * p = GTS_POINT (*o);
+
+  if (GTS_POINT_CLASS ((*o)->klass)->binary) {
+    if (gts_file_read (f, &(p->x), sizeof (gdouble), 1) != 1) {
+      gts_file_error (f, "expecting a binary number (x coordinate)");
+      return;
+    }
+    if (gts_file_read (f, &(p->y), sizeof (gdouble), 1) != 1) {
+      gts_file_error (f, "expecting a binary number (y coordinate)");
+      return;
+    }
+    if (gts_file_read (f, &(p->z), sizeof (gdouble), 1) != 1) {
+      gts_file_error (f, "expecting a binary number (z coordinate)");
+      return;
+    }
+  }
+  else {
+    if (f->type != GTS_INT && f->type != GTS_FLOAT) {
+      gts_file_error (f, "expecting a number (x coordinate)");
+      return;
+    }
+    p->x = atof (f->token->str);
+    
+    gts_file_next_token (f);
+    if (f->type != GTS_INT && f->type != GTS_FLOAT) {
+      gts_file_error (f, "expecting a number (y coordinate)");
+      return;
+    }
+    p->y = atof (f->token->str);
+    
+    gts_file_next_token (f);
+    if (f->type != GTS_INT && f->type != GTS_FLOAT) {
+      gts_file_error (f, "expecting a number (z coordinate)");
+      return;
+    }
+    p->z = atof (f->token->str);
+    
+    gts_file_next_token (f);
+  }
+}
+
+static void point_write (GtsObject * o, FILE * fptr)
+{
+  GtsPoint * p = GTS_POINT (o);
+
+  if (GTS_POINT_CLASS ((o)->klass)->binary) {
+    fwrite (&(p->x), sizeof (gdouble), 1, fptr);
+    fwrite (&(p->y), sizeof (gdouble), 1, fptr);
+    fwrite (&(p->z), sizeof (gdouble), 1, fptr);
+  }
+  else
+    fprintf (fptr, "%.10g %.10g %.10g", p->x, p->y, p->z);
+}
+
+static void point_class_init (GtsObjectClass * klass)
+{
+  klass->read = point_read;
+  klass->write = point_write;
+}
+
+/**
+ * gts_point_class:
+ *
+ * Returns: the #GtsPointClass.
+ */
+GtsPointClass * gts_point_class (void)
+{
+  static GtsPointClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo point_info = {
+      "GtsPoint",
+      sizeof (GtsPoint),
+      sizeof (GtsPointClass),
+      (GtsObjectClassInitFunc) point_class_init,
+      (GtsObjectInitFunc) NULL,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (gts_object_class (), 
+				  &point_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_point_new:
+ * @klass: a #GtsPointClass.
+ * @x: the x-coordinate.
+ * @y: the y-coordinate.
+ * @z: the z-coordinate.
+ *
+ * Returns: a new #GtsPoint.
+ */
+GtsPoint * gts_point_new (GtsPointClass * klass,
+			  gdouble x, gdouble y, gdouble z)
+{
+  GtsPoint * p;
+  
+  p = GTS_POINT (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  p->x = x;
+  p->y = y;
+  p->z = z;
+
+  return p;
+}
+
+/**
+ * gts_point_set:
+ * @p: a #GtsPoint.
+ * @x: the x-coordinate.
+ * @y: the y-coordinate.
+ * @z: the z-coordinate.
+ *
+ * Sets the coordinates of @p.
+ */
+void gts_point_set (GtsPoint * p, gdouble x, gdouble y, gdouble z)
+{
+  g_return_if_fail (p != NULL);
+
+  p->x = x;
+  p->y = y;
+  p->z = z;
+}
+
+/**
+ * gts_point_distance:
+ * @p1: a #GtsPoint.
+ * @p2: another #GtsPoint.
+ *
+ * Returns: the Euclidean distance between @p1 and @p2.
+ */
+gdouble gts_point_distance (GtsPoint * p1, GtsPoint * p2)
+{
+  g_return_val_if_fail (p1 != NULL && p2 != NULL, 0.0);
+  
+  return sqrt ((p1->x - p2->x)*(p1->x - p2->x) + 
+	       (p1->y - p2->y)*(p1->y - p2->y) + 
+	       (p1->z - p2->z)*(p1->z - p2->z));
+}
+
+/**
+ * gts_point_distance2:
+ * @p1: a #GtsPoint.
+ * @p2: another #GtsPoint.
+ *
+ * Returns: the square of the Euclidean distance between @p1 and @p2.
+ */
+gdouble gts_point_distance2 (GtsPoint * p1, GtsPoint * p2)
+{
+  g_return_val_if_fail (p1 != NULL && p2 != NULL, 0.0);
+  
+  return
+    (p1->x - p2->x)*(p1->x - p2->x) +
+    (p1->y - p2->y)*(p1->y - p2->y) + 
+    (p1->z - p2->z)*(p1->z - p2->z);
+}
+
+/**
+ * gts_point_orientation_3d:
+ * @p1: a #GtsPoint.
+ * @p2: a #GtsPoint.
+ * @p3: a #GtsPoint.
+ * @p4: a #GtsPoint.
+ *
+ * Checks if @p4 lies above, below or on the plane passing through the
+ * points @p1, @p2 and @p3. Below is defined so that @p1, @p2 and @p3
+ * appear in counterclockwise order when viewed from above the
+ * plane. The returned value is an approximation of six times the
+ * signed volume of the tetrahedron defined by the four points. This
+ * function uses adaptive floating point arithmetic and is
+ * consequently geometrically robust.
+ *
+ * Returns: a positive value if @p4 lies below, a negative value if
+ * @p4 lies above the plane, zero if the four points are coplanar.  
+ */
+gdouble gts_point_orientation_3d (GtsPoint * p1,
+				  GtsPoint * p2,
+				  GtsPoint * p3,
+				  GtsPoint * p4)
+{
+  g_return_val_if_fail (p1 != NULL && p2 != NULL && 
+			p3 != NULL && p4 != NULL, 0.0);
+  return orient3d ((gdouble *) &p1->x, 
+		   (gdouble *) &p2->x, 
+		   (gdouble *) &p3->x, 
+		   (gdouble *) &p4->x);
+}
+
+/**
+ * gts_point_is_in_triangle:
+ * @p: a #GtsPoint.
+ * @t: a #GtsTriangle.
+ *
+ * Tests if the planar projection (x, y) of @p is inside, outside or
+ * on the boundary of the planar projection of @t.  This function is
+ * geometrically robust.
+ * 
+ * Returns: %GTS_IN if @p is inside @t, %GTS_ON if @p is on the boundary of
+ * @t, %GTS_OUT otherwise.  
+ */
+GtsIntersect gts_point_is_in_triangle (GtsPoint * p, GtsTriangle * t)
+{
+  GtsVertex * v1, * v2, * v3;
+  gdouble d1, d2, d3;
+
+  g_return_val_if_fail (p != NULL && t != NULL, FALSE);
+
+  gts_triangle_vertices (t, &v1, &v2, &v3);
+
+  d1 = gts_point_orientation (GTS_POINT (v1), GTS_POINT (v2), p);
+  if (d1 < 0.0)
+    return GTS_OUT;
+  d2 = gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), p);
+  if (d2 < 0.0)
+    return GTS_OUT;
+  d3 = gts_point_orientation (GTS_POINT (v3), GTS_POINT (v1), p);
+  if (d3 < 0.0)
+    return GTS_OUT;
+  if (d1 == 0.0 || d2 == 0.0 || d3 == 0.0)
+    return GTS_ON;
+  return GTS_IN;
+}
+
+/**
+ * gts_point_in_triangle_circle:
+ * @p: a #GtsPoint.
+ * @t: a #GtsTriangle.
+ *
+ * Tests if the planar projection (x, y) of @p is inside or outside
+ * the circumcircle of the planar projection of @t. This function is
+ * geometrically robust.
+ * 
+ * Returns: a positive number if @p lies inside,
+ * a negative number if @p lies outside and zero if @p lies on 
+ * the circumcircle of @t.  
+ */
+gdouble gts_point_in_triangle_circle (GtsPoint * p, GtsTriangle * t)
+{
+  GtsPoint * p1, * p2, * p3;
+
+  g_return_val_if_fail (p != NULL && t != NULL, 0.0);
+
+  gts_triangle_vertices (t, 
+			 (GtsVertex **) &p1, 
+			 (GtsVertex **) &p2, 
+			 (GtsVertex **) &p3);
+
+  return incircle ((gdouble *) &p1->x, 
+		   (gdouble *) &p2->x, 
+		   (gdouble *) &p3->x, 
+		   (gdouble *) &p->x);
+}
+
+/**
+ * gts_point_in_circle:
+ * @p: a #GtsPoint.
+ * @p1: a #GtsPoint.
+ * @p2: a #GtsPoint.
+ * @p3: a #GtsPoint.
+ *
+ * Tests if the planar projection (x, y) of @p is inside or outside the
+ * circle defined by the planar projection of @p1, @p2 and @p3.
+ * 
+ * Returns: a positive number if @p lies inside,
+ * a negative number if @p lies outside and zero if @p lies on 
+ * the circle.
+ */
+gdouble gts_point_in_circle (GtsPoint * p, 
+			     GtsPoint * p1, GtsPoint * p2, GtsPoint * p3)
+{
+  g_return_val_if_fail (p != NULL && p1 != NULL && p2 != NULL && p3 != NULL, 
+			0.0);
+
+  return incircle ((gdouble *) &p1->x, 
+		   (gdouble *) &p2->x, 
+		   (gdouble *) &p3->x, 
+		   (gdouble *) &p->x);
+}
+
+/**
+ * gts_point_in_sphere:
+ * @p: a #GtsPoint.
+ * @p1: a #GtsPoint.
+ * @p2: a #GtsPoint.
+ * @p3: a #GtsPoint.
+ * @p4: a #GtsPoint.
+ *
+ * Tests if @p is inside or outside the sphere defined by @p1, @p2,
+ * @p3 and @p4.
+ * 
+ * Returns: a positive number if @p lies inside,
+ * a negative number if @p lies outside and zero if @p lies on 
+ * the sphere.
+ */
+gdouble gts_point_in_sphere (GtsPoint * p, 
+			     GtsPoint * p1, GtsPoint * p2, GtsPoint * p3, GtsPoint * p4)
+{
+  g_return_val_if_fail (p != NULL && p1 != NULL && p2 != NULL && p3 != NULL && p4 != NULL, 
+			0.0);
+
+  return insphere ((gdouble *) &p1->x, 
+		   (gdouble *) &p2->x, 
+		   (gdouble *) &p3->x, 
+		   (gdouble *) &p4->x, 
+		   (gdouble *) &p->x);
+}
+
+/**
+ * gts_point_segment_distance2:
+ * @p: a #GtsPoint.
+ * @s: a #GtsSegment.
+ *
+ * Returns: the square of the minimun Euclidean distance between @p and @s.
+ */
+gdouble gts_point_segment_distance2 (GtsPoint * p, GtsSegment * s)
+{
+  gdouble t, ns2, x, y, z;
+  GtsPoint * p1, * p2;
+
+  g_return_val_if_fail (p != NULL, 0.0);
+  g_return_val_if_fail (s != NULL, 0.0);
+
+  p1 = GTS_POINT (s->v1);
+  p2 = GTS_POINT (s->v2);
+  ns2 = gts_point_distance2 (p1, p2);
+  if (ns2 == 0.0)
+    return gts_point_distance2 (p, p1);
+  t = ((p2->x - p1->x)*(p->x - p1->x) + 
+       (p2->y - p1->y)*(p->y - p1->y) +
+       (p2->z - p1->z)*(p->z - p1->z))/ns2;
+  if (t > 1.0)
+    return gts_point_distance2 (p, p2);
+  if (t < 0.0)
+    return gts_point_distance2 (p, p1);
+  x = (1. - t)*p1->x + t*p2->x - p->x;
+  y = (1. - t)*p1->y + t*p2->y - p->y;
+  z = (1. - t)*p1->z + t*p2->z - p->z;
+  return x*x + y*y + z*z;
+}
+
+/**
+ * gts_point_segment_distance:
+ * @p: a #GtsPoint.
+ * @s: a #GtsSegment.
+ *
+ * Returns: the minimun Euclidean distance between @p and @s.
+ */
+gdouble gts_point_segment_distance (GtsPoint * p, GtsSegment * s)
+{
+  g_return_val_if_fail (p != NULL, 0.0);
+  g_return_val_if_fail (s != NULL, 0.0);
+
+  return sqrt (gts_point_segment_distance2 (p, s));
+}
+
+/**
+ * gts_point_segment_closest:
+ * @p: a #GtsPoint.
+ * @s: a #GtsSegment.
+ * @closest: a #GtsPoint.
+ *
+ * Set the coordinates of @closest to the coordinates of the point belonging
+ * to @s closest to @p.
+ */
+void gts_point_segment_closest (GtsPoint * p, 
+				GtsSegment * s,
+				GtsPoint * closest)
+{
+  gdouble t, ns2;
+  GtsPoint * p1, * p2;
+
+  g_return_if_fail (p != NULL);
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (closest != NULL);
+
+  p1 = GTS_POINT (s->v1);
+  p2 = GTS_POINT (s->v2);
+  ns2 = gts_point_distance2 (p1, p2);
+
+  if (ns2 == 0.0) {
+    gts_point_set (closest, p1->x, p1->y, p1->z);
+    return;
+  }
+
+  t = ((p2->x - p1->x)*(p->x - p1->x) + 
+       (p2->y - p1->y)*(p->y - p1->y) +
+       (p2->z - p1->z)*(p->z - p1->z))/ns2;
+
+  if (t > 1.0)
+    gts_point_set (closest, p2->x, p2->y, p2->z);
+  else if (t < 0.0)
+    gts_point_set (closest, p1->x, p1->y, p1->z);
+  else
+    gts_point_set (closest,
+		   (1. - t)*p1->x + t*p2->x,
+		   (1. - t)*p1->y + t*p2->y,
+		   (1. - t)*p1->z + t*p2->z);
+}
+
+/**
+ * gts_point_triangle_distance2:
+ * @p: a #GtsPoint.
+ * @t: a #GtsTriangle.
+ *
+ * Returns: the square of the minimun Euclidean distance between @p and @t.
+ */
+gdouble gts_point_triangle_distance2 (GtsPoint * p, GtsTriangle * t)
+{
+  GtsPoint * p1, * p2, * p3;
+  GtsEdge * e1, * e2, * e3;
+  GtsVector p1p2, p1p3, pp1;
+  gdouble A, B, C, D, E, det;
+  gdouble t1, t2;
+  gdouble x, y, z;
+
+  g_return_val_if_fail (p != NULL, 0.0);
+  g_return_val_if_fail (t != NULL, 0.0);
+
+  gts_triangle_vertices_edges (t, NULL, 
+			       (GtsVertex **) &p1, 
+			       (GtsVertex **) &p2, 
+			       (GtsVertex **) &p3, 
+			       &e1, &e2, &e3);
+
+  gts_vector_init (p1p2, p1, p2);
+  gts_vector_init (p1p3, p1, p3);
+  gts_vector_init (pp1, p, p1);
+
+  B = gts_vector_scalar (p1p3, p1p2);
+  E = gts_vector_scalar (p1p2, p1p2);
+  C = gts_vector_scalar (p1p3, p1p3);
+  
+  det = B*B - E*C;
+  if (det == 0.) { /* p1p2 and p1p3 are colinear */
+    gdouble d1 = gts_point_segment_distance2 (p, GTS_SEGMENT (e1));
+    gdouble d2 = gts_point_segment_distance2 (p, GTS_SEGMENT (e3));
+    if (d1 < d2)
+      return d1;
+    return d2;
+  }
+
+  A = gts_vector_scalar (p1p3, pp1);
+  D = gts_vector_scalar (p1p2, pp1);
+  
+  t1 = (D*C - A*B)/det;
+  t2 = (A*E - D*B)/det;
+
+  if (t1 < 0.)
+    return gts_point_segment_distance2 (p, GTS_SEGMENT (e3));
+  if (t2 < 0.)
+    return gts_point_segment_distance2 (p, GTS_SEGMENT (e1));
+  if (t1 + t2 > 1.)
+    return gts_point_segment_distance2 (p, GTS_SEGMENT (e2));
+
+  x = pp1[0] + t1*p1p2[0] + t2*p1p3[0];
+  y = pp1[1] + t1*p1p2[1] + t2*p1p3[1];
+  z = pp1[2] + t1*p1p2[2] + t2*p1p3[2];
+
+  return x*x + y*y + z*z;
+}
+
+/**
+ * gts_point_triangle_distance:
+ * @p: a #GtsPoint.
+ * @t: a #GtsTriangle.
+ *
+ * Returns: the minimun Euclidean distance between @p and @t.
+ */
+gdouble gts_point_triangle_distance (GtsPoint * p, GtsTriangle * t)
+{
+  g_return_val_if_fail (p != NULL, 0.0);
+  g_return_val_if_fail (t != NULL, 0.0);
+
+  return sqrt (gts_point_triangle_distance2 (p, t));
+}
+
+/**
+ * gts_point_triangle_closest:
+ * @p: a #GtsPoint.
+ * @t: a #GtsTriangle.
+ * @closest: a #GtsPoint.
+ *
+ * Set the coordinates of @closest to those of the point belonging to @t and 
+ * closest to @p.
+ */
+void gts_point_triangle_closest (GtsPoint * p, 
+				 GtsTriangle * t, 
+				 GtsPoint * closest)
+{
+  GtsPoint * p1, * p2, * p3;
+  GtsEdge * e1, * e2, * e3;
+  GtsVector p1p2, p1p3, pp1;
+  gdouble A, B, C, D, E, det;
+  gdouble t1, t2;
+
+  g_return_if_fail (p != NULL);
+  g_return_if_fail (t != NULL);
+  g_return_if_fail (closest != NULL);
+
+  gts_triangle_vertices_edges (t, NULL, 
+			       (GtsVertex **) &p1, 
+			       (GtsVertex **) &p2, 
+			       (GtsVertex **) &p3, 
+			       &e1, &e2, &e3);
+
+  gts_vector_init (p1p2, p1, p2);
+  gts_vector_init (p1p3, p1, p3);
+  gts_vector_init (pp1, p, p1);
+
+  B = gts_vector_scalar (p1p3, p1p2);
+  E = gts_vector_scalar (p1p2, p1p2);
+  C = gts_vector_scalar (p1p3, p1p3);
+  
+  det = B*B - E*C;
+  if (det == 0.) { /* p1p2 and p1p3 are colinear */
+    GtsPoint * cp = 
+      GTS_POINT (gts_object_new (GTS_OBJECT_CLASS (gts_point_class ())));
+    gts_point_segment_closest (p, GTS_SEGMENT (e1), cp);
+    gts_point_segment_closest (p, GTS_SEGMENT (e3), closest);
+
+    if (gts_point_distance2 (cp, p) < gts_point_distance2 (closest, p))
+      gts_point_set (closest, cp->x, cp->y, cp->z);
+    gts_object_destroy (GTS_OBJECT (cp));
+    return;
+  }
+
+  A = gts_vector_scalar (p1p3, pp1);
+  D = gts_vector_scalar (p1p2, pp1);
+  
+  t1 = (D*C - A*B)/det;
+  t2 = (A*E - D*B)/det;
+
+  if (t1 < 0.)
+    gts_point_segment_closest (p, GTS_SEGMENT (e3), closest);
+  else if (t2 < 0.)
+    gts_point_segment_closest (p, GTS_SEGMENT (e1), closest);
+  else if (t1 + t2 > 1.)
+    gts_point_segment_closest (p, GTS_SEGMENT (e2), closest);
+  else
+    gts_point_set (closest, 
+		   p1->x + t1*p1p2[0] + t2*p1p3[0],
+		   p1->y + t1*p1p2[1] + t2*p1p3[1],
+		   p1->z + t1*p1p2[2] + t2*p1p3[2]);
+}
+
+/**
+ * gts_segment_triangle_intersection:
+ * @s: a #GtsSegment.
+ * @t: a #GtsTriangle.
+ * @boundary: if %TRUE, the boundary of @t is taken into account.
+ * @klass: a #GtsPointClass to be used for the new point.
+ *
+ * Checks if @s intersects @t. If this is the case, creates a new
+ * point pi intersection of @s with @t.
+ *
+ * This function is geometrically robust in the sense that it will not
+ * return a point if @s and @t do not intersect and will return a
+ * point if @s and @t do intersect. However, the point coordinates are
+ * subject to round-off errors.
+ *
+ * Note that this function will not return any point if @s is contained in
+ * the plane defined by @t.
+ * 
+ * Returns: a summit of @t (if @boundary is set to %TRUE), one of the endpoints
+ * of @s or a new #GtsPoint, intersection of @s with @t or %NULL if @s 
+ * and @t don't intersect.  
+ */
+GtsPoint * gts_segment_triangle_intersection (GtsSegment * s,
+					      GtsTriangle * t,
+					      gboolean boundary,
+					      GtsPointClass * klass)
+{
+  GtsPoint * A, * B, * C, * D, * E, * I;
+  gdouble ABCE, ABCD, ADCE, ABDE, BCDE;
+  gdouble c;
+
+  g_return_val_if_fail (s != NULL, NULL);
+  g_return_val_if_fail (t != NULL, NULL);
+  g_return_val_if_fail (klass != NULL, NULL);
+
+  A = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
+  B = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
+  C = GTS_POINT (gts_triangle_vertex (t));
+  D = GTS_POINT (s->v1); 
+  E = GTS_POINT (s->v2);
+
+  ABCE = gts_point_orientation_3d (A, B, C, E);
+  ABCD = gts_point_orientation_3d (A, B, C, D);
+  if (ABCE < 0.0 || ABCD > 0.0) {
+    GtsPoint * tmpp;
+    gdouble tmp;
+    tmpp = E; E = D; D = tmpp;
+    tmp = ABCE; ABCE = ABCD; ABCD = tmp;
+  }
+  if (ABCE < 0.0 || ABCD > 0.0)
+    return NULL;
+  ADCE = gts_point_orientation_3d (A, D, C, E);
+  if ((boundary && ADCE < 0.) || (!boundary && ADCE <= 0.))
+    return NULL;
+  ABDE = gts_point_orientation_3d (A, B, D, E);
+  if ((boundary && ABDE < 0.) || (!boundary && ABDE <= 0.))
+    return NULL;
+  BCDE = gts_point_orientation_3d (B, C, D, E);
+  if ((boundary && BCDE < 0.) || (!boundary && BCDE <= 0.))
+    return NULL;
+  if (ABCE == 0.0) {
+    if (ABCD == 0.0)
+      /* s is contained in the plane defined by t*/
+      return NULL;
+    return E;
+  }
+  if (ABCD == 0.0)
+    return D;
+  if (boundary) { /* corners of @t */
+    if (ABDE == 0.) {
+      if (ADCE == 0.)
+	return A;
+      if (BCDE == 0.)
+	return B;
+    }
+    else if (BCDE == 0. && ADCE == 0.)
+      return C;
+  }
+  c = ABCE/(ABCE - ABCD);
+  I = GTS_POINT (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  gts_point_set (I,
+		 E->x + c*(D->x - E->x),
+		 E->y + c*(D->y - E->y),
+		 E->z + c*(D->z - E->z));
+  return I;
+}
+
+/**
+ * gts_point_transform:
+ * @p: a #GtsPoint.
+ * @m: the #GtsMatrix representing the transformation to 
+ * apply to the coordinates of @p.
+ *
+ * Transform the coordinates of @p according to @m. (p[] becomes m[][].p[]).
+ */
+void gts_point_transform (GtsPoint * p, GtsMatrix * m)
+{
+  gdouble x, y, z;
+  g_return_if_fail (p != NULL && m != NULL);
+  x = m[0][0]*p->x + m[0][1]*p->y + m[0][2]*p->z + m[0][3];
+  y = m[1][0]*p->x + m[1][1]*p->y + m[1][2]*p->z + m[1][3];
+  z = m[2][0]*p->x + m[2][1]*p->y + m[2][2]*p->z + m[2][3];
+  p->x = x; p->y = y; p->z = z;
+}
+
+/**
+ * gts_point_orientation:
+ * @p1: a #GtsPoint.
+ * @p2: a #GtsPoint.
+ * @p3: a #GtsPoint.
+ *
+ * Checks for orientation of the projection of three points on the
+ * (x,y) plane. The result is also an approximation of twice the
+ * signed area of the triangle defined by the three points. This
+ * function uses adaptive floating point arithmetic and is
+ * consequently geometrically robust.
+ *
+ * Returns: a positive value if @p1, @p2 and @p3 appear in
+ * counterclockwise order, a negative value if they appear in
+ * clockwise order and zero if they are colinear.  
+ */
+gdouble gts_point_orientation (GtsPoint * p1, GtsPoint * p2, GtsPoint * p3)
+{
+  g_return_val_if_fail (p1 != NULL && p2 != NULL && p3 != NULL, 0.0);
+
+  return orient2d ((gdouble *) &p1->x, 
+		   (gdouble *) &p2->x, 
+		   (gdouble *) &p3->x);
+}
+
+static gboolean ray_intersects_triangle (GtsPoint * D, GtsPoint * E,
+					 GtsTriangle * t)
+{
+  GtsPoint * A, * B, * C;
+  gint ABCE, ABCD, ADCE, ABDE, BCDE;
+
+  gts_triangle_vertices (t, (GtsVertex **) &A, 
+			 (GtsVertex **) &B, 
+			 (GtsVertex **) &C);
+
+  ABCE = gts_point_orientation_3d_sos (A, B, C, E);
+  ABCD = gts_point_orientation_3d_sos (A, B, C, D);
+  if (ABCE < 0 || ABCD > 0) {
+    GtsPoint * tmpp;
+    gint tmp;
+
+    tmpp = E; E = D; D = tmpp;
+    tmp = ABCE; ABCE = ABCD; ABCD = tmp;
+  }
+  if (ABCE < 0 || ABCD > 0)
+    return FALSE;
+  ADCE = gts_point_orientation_3d_sos (A, D, C, E);
+  if (ADCE < 0)
+    return FALSE;
+  ABDE = gts_point_orientation_3d_sos (A, B, D, E);
+  if (ABDE < 0)
+    return FALSE;
+  BCDE = gts_point_orientation_3d_sos (B, C, D, E);
+  if (BCDE < 0)
+    return FALSE;
+  return TRUE;
+}
+
+/** 
+ * gts_point_is_inside_surface: 
+ * @p: a #GtsPoint.  
+ * @tree: a bounding box tree of the faces of a closed, orientable
+ * surface (see gts_bb_tree_surface()).
+ * @is_open: %TRUE if the surface defined by @tree is "open" i.e. its volume 
+ * is negative, %FALSE otherwise.
+ *
+ * Returns: %TRUE if @p is inside the surface defined by @tree, %FALSE
+ * otherwise.  
+ */
+gboolean gts_point_is_inside_surface (GtsPoint * p, 
+				      GNode * tree,
+				      gboolean is_open)
+{
+  GSList * list, * i;
+  guint nc = 0;
+  GtsPoint * p1;
+  GtsBBox * bb;
+
+  g_return_val_if_fail (p != NULL, FALSE);
+  g_return_val_if_fail (tree != NULL, FALSE);
+
+  bb = tree->data;
+  p1 = gts_point_new (gts_point_class (), bb->x2 + fabs (bb->x2)/10., p->y, p->z);
+  i = list = gts_bb_tree_stabbed (tree, p);
+  while (i) {
+    GtsTriangle * t = GTS_TRIANGLE (GTS_BBOX (i->data)->bounded);
+
+    if (ray_intersects_triangle (p, p1, t))
+      nc++;
+    i = i->next;
+  }
+  g_slist_free (list);
+  gts_object_destroy (GTS_OBJECT (p1));
+
+  return is_open ? (nc % 2 == 0) : (nc % 2 != 0);
+}
+
+#define SIGN(x) ((x) > 0. ? 1 : -1)
+#define ORIENT1D(a,b) ((a) > (b) ? 1 : (a) < (b) ? -1 : 0)
+
+static gint sortp (gpointer * p, guint n)
+{
+  gint sign = 1;
+  guint i, j;
+
+  for (i = 0; i < n - 1; i++)
+    for (j = 0; j < n - 1 - i; j++)
+      if (GPOINTER_TO_UINT (p[j+1]) < GPOINTER_TO_UINT (p[j])) {
+	gpointer tmp = p[j];
+
+	p[j] = p[j+1];
+	p[j+1] = tmp;
+	sign = - sign;
+      }
+  return sign;
+}
+
+/**
+ * gts_point_orientation_3d_sos:
+ * @p1: a #GtsPoint.
+ * @p2: a #GtsPoint.
+ * @p3: a #GtsPoint.
+ * @p4: a #GtsPoint.
+ *
+ * Checks if @p4 lies above or below the plane passing through the
+ * points @p1, @p2 and @p3. Below is defined so that @p1, @p2 and @p3
+ * appear in counterclockwise order when viewed from above the
+ * plane. This function uses adaptive floating point arithmetic and is
+ * consequently geometrically robust.
+ *
+ * Simulation of Simplicity (SoS) is used to break ties when the
+ * orientation is degenerate (i.e. @p4 lies on the plane defined by
+ * @p1, @p2 and @p3).
+ *
+ * Returns: +1 if @p4 lies below, -1 if @p4 lies above the plane.  
+ */
+gint gts_point_orientation_3d_sos (GtsPoint * p1,
+				   GtsPoint * p2,
+				   GtsPoint * p3,
+				   GtsPoint * p4)
+{
+  gdouble o;
+
+  g_return_val_if_fail (p1 != NULL && p2 != NULL && 
+			p3 != NULL && p4 != NULL, 0);
+
+  o = orient3d ((gdouble *) &p1->x, 
+		(gdouble *) &p2->x, 
+		(gdouble *) &p3->x, 
+		(gdouble *) &p4->x);
+  if (o != 0.)
+    return SIGN (o);
+  else {
+    GtsPoint * p[4];
+    gdouble a[2], b[2], c[2];
+    gint sign;
+
+    p[0] = p1; p[1] = p2; p[2] = p3; p[3] = p4;
+    sign = sortp ((gpointer *) p, 4);
+    
+    /* epsilon^1/8 */
+    a[0] = p[1]->x; a[1] = p[1]->y;
+    b[0] = p[2]->x; b[1] = p[2]->y;
+    c[0] = p[3]->x; c[1] = p[3]->y;
+    o = orient2d (a, b, c);
+    if (o != 0.)
+      return SIGN (o)*sign;
+    
+    /* epsilon^1/4 */
+    a[0] = p[1]->x; a[1] = p[1]->z;
+    b[0] = p[2]->x; b[1] = p[2]->z;
+    c[0] = p[3]->x; c[1] = p[3]->z;
+    o = orient2d (a, b, c);
+    if (o != 0.)
+      return - SIGN (o)*sign;
+    
+    /* epsilon^1/2 */
+    a[0] = p[1]->y; a[1] = p[1]->z;
+    b[0] = p[2]->y; b[1] = p[2]->z;
+    c[0] = p[3]->y; c[1] = p[3]->z;
+    o = orient2d (a, b, c);
+    if (o != 0.)
+      return SIGN (o)*sign;
+    
+    /* epsilon */
+    a[0] = p[0]->x; a[1] = p[0]->y;
+    b[0] = p[2]->x; b[1] = p[2]->y;
+    c[0] = p[3]->x; c[1] = p[3]->y;
+    o = orient2d (a, b, c);
+    if (o != 0.)
+      return - SIGN (o)*sign;
+    
+    /* epsilon^5/4 */
+    o = ORIENT1D (p[2]->x, p[3]->x);
+    if (o != 0.)
+      return SIGN (o)*sign;
+    
+    /* epsilon^3/2 */
+    o = ORIENT1D (p[2]->y, p[3]->y);
+    if (o != 0.)
+      return - SIGN (o)*sign;
+    
+    /* epsilon^2 */
+    a[0] = p[0]->x; a[1] = p[0]->z;
+    b[0] = p[2]->x; b[1] = p[2]->z;
+    c[0] = p[3]->x; c[1] = p[3]->z;
+    o = orient2d (a, b, c);
+    if (o != 0.)
+      return SIGN (o)*sign;
+
+    /* epsilon^5/2 */
+    o = ORIENT1D (p[2]->z, p[3]->z);
+    if (o != 0.)
+      return SIGN (o)*sign;
+    
+    /* epsilon^4 */
+    a[0] = p[0]->y; a[1] = p[0]->z;
+    b[0] = p[2]->y; b[1] = p[2]->z;
+    c[0] = p[3]->y; c[1] = p[3]->z;
+    o = orient2d (a, b, c);
+    if (o != 0.)
+      return - SIGN (o)*sign;
+
+    /* epsilon^8 */
+    a[0] = p[0]->x; a[1] = p[0]->y;
+    b[0] = p[1]->x; b[1] = p[1]->y;
+    c[0] = p[3]->x; c[1] = p[3]->y;
+    o = orient2d (a, b, c);
+    if (o != 0.)
+      return SIGN (o)*sign;
+
+    /* epsilon^33/4 */
+    o = ORIENT1D (p[1]->x, p[3]->x);
+    if (o != 0.)
+      return - SIGN (o)*sign;
+    
+    /* epsilon^17/2 */
+    o = ORIENT1D (p[1]->y, p[3]->y);
+    if (o != 0.)
+      return SIGN (o)*sign;
+    
+    /* epsilon^10 */
+    o = ORIENT1D (p[0]->x, p[3]->x);
+    if (o != 0.)
+      return SIGN (o)*sign;
+    
+    /* epsilon^21/2 */
+    return sign;
+  }
+}
+
+/**
+ * gts_point_orientation_sos:
+ * @p1: a #GtsPoint.
+ * @p2: a #GtsPoint.
+ * @p3: a #GtsPoint.
+ *
+ * Checks for orientation of the projection of three points on the
+ * (x,y) plane.
+ *
+ * Simulation of Simplicity (SoS) is used to break ties when the
+ * orientation is degenerate (i.e. @p3 lies on the line defined by
+ * @p1 and @p2).
+ *
+ * Returns: a positive value if @p1, @p2 and @p3 appear in
+ * counterclockwise order or a negative value if they appear in
+ * clockwise order.  
+ */
+gint gts_point_orientation_sos (GtsPoint * p1,
+				GtsPoint * p2,
+				GtsPoint * p3)
+{
+  gdouble o;
+
+  g_return_val_if_fail (p1 != NULL && p2 != NULL && p3 != NULL, 0);
+
+  o = orient2d ((gdouble *) &p1->x, 
+		(gdouble *) &p2->x, 
+		(gdouble *) &p3->x);
+  if (o != 0.)
+    return SIGN (o);
+  else {
+    GtsPoint * p[3];
+    gint sign;
+
+    p[0] = p1; p[1] = p2; p[2] = p3;
+    sign = sortp ((gpointer *) p, 3);
+    
+    /* epsilon^1/4 */
+    o = ORIENT1D (p[1]->x, p[2]->x);
+    if (o != 0.)
+      return - SIGN (o)*sign;
+    
+    /* epsilon^1/2 */
+    o = ORIENT1D (p[1]->y, p[2]->y);
+    if (o != 0.)
+      return SIGN (o)*sign;
+    
+    /* epsilon */
+    o = ORIENT1D (p[0]->x, p[2]->x);
+    if (o != 0.)
+      return SIGN (o)*sign;
+    
+    /* epsilon^3/2 */
+    return sign;
+  }
+}
diff --git a/gts/predicates.c b/gts/predicates.c
new file mode 100644
index 0000000..7b7fcf2
--- /dev/null
+++ b/gts/predicates.c
@@ -0,0 +1,2742 @@
+/*****************************************************************************/
+/*                                                                           */
+/*  Routines for Arbitrary Precision Floating-point Arithmetic               */
+/*  and Fast Robust Geometric Predicates                                     */
+/*  (predicates.c)                                                           */
+/*                                                                           */
+/*  May 18, 1996                                                             */
+/*                                                                           */
+/*  Placed in the public domain by                                           */
+/*  Jonathan Richard Shewchuk                                                */
+/*  School of Computer Science                                               */
+/*  Carnegie Mellon University                                               */
+/*  5000 Forbes Avenue                                                       */
+/*  Pittsburgh, Pennsylvania  15213-3891                                     */
+/*  jrs@xxxxxxxxxx                                                           */
+/*                                                                           */
+/*  This file contains C implementation of algorithms for exact addition     */
+/*    and multiplication of floating-point numbers, and predicates for       */
+/*    robustly performing the orientation and incircle tests used in         */
+/*    computational geometry.  The algorithms and underlying theory are      */
+/*    described in Jonathan Richard Shewchuk.  "Adaptive Precision Floating- */
+/*    Point Arithmetic and Fast Robust Geometric Predicates."  Technical     */
+/*    Report CMU-CS-96-140, School of Computer Science, Carnegie Mellon      */
+/*    University, Pittsburgh, Pennsylvania, May 1996.  (Submitted to         */
+/*    Discrete & Computational Geometry.)                                    */
+/*                                                                           */
+/*  This file, the paper listed above, and other information are available   */
+/*    from the Web page http://www.cs.cmu.edu/~quake/robust.html .           */
+/*                                                                           */
+/*****************************************************************************/
+
+/*****************************************************************************/
+/*                                                                           */
+/*  Using this code:                                                         */
+/*                                                                           */
+/*  First, read the short or long version of the paper (from the Web page    */
+/*    above).                                                                */
+/*                                                                           */
+/*  Be sure to call exactinit() once, before calling any of the arithmetic   */
+/*    functions or geometric predicates.  Also be sure to turn on the        */
+/*    optimizer when compiling this file.                                    */
+/*                                                                           */
+/*                                                                           */
+/*  Several geometric predicates are defined.  Their parameters are all      */
+/*    points.  Each point is an array of two or three floating-point         */
+/*    numbers.  The geometric predicates, described in the papers, are       */
+/*                                                                           */
+/*    orient2d(pa, pb, pc)                                                   */
+/*    orient2dfast(pa, pb, pc)                                               */
+/*    orient3d(pa, pb, pc, pd)                                               */
+/*    orient3dfast(pa, pb, pc, pd)                                           */
+/*    incircle(pa, pb, pc, pd)                                               */
+/*    incirclefast(pa, pb, pc, pd)                                           */
+/*    insphere(pa, pb, pc, pd, pe)                                           */
+/*    inspherefast(pa, pb, pc, pd, pe)                                       */
+/*                                                                           */
+/*  Those with suffix "fast" are approximate, non-robust versions.  Those    */
+/*    without the suffix are adaptive precision, robust versions.  There     */
+/*    are also versions with the suffices "exact" and "slow", which are      */
+/*    non-adaptive, exact arithmetic versions, which I use only for timings  */
+/*    in my arithmetic papers.                                               */
+/*                                                                           */
+/*                                                                           */
+/*  An expansion is represented by an array of floating-point numbers,       */
+/*    sorted from smallest to largest magnitude (possibly with interspersed  */
+/*    zeros).  The length of each expansion is stored as a separate integer, */
+/*    and each arithmetic function returns an integer which is the length    */
+/*    of the expansion it created.                                           */
+/*                                                                           */
+/*  Several arithmetic functions are defined.  Their parameters are          */
+/*                                                                           */
+/*    e, f           Input expansions                                        */
+/*    elen, flen     Lengths of input expansions (must be >= 1)              */
+/*    h              Output expansion                                        */
+/*    b              Input scalar                                            */
+/*                                                                           */
+/*  The arithmetic functions are                                             */
+/*                                                                           */
+/*    grow_expansion(elen, e, b, h)                                          */
+/*    grow_expansion_zeroelim(elen, e, b, h)                                 */
+/*    expansion_sum(elen, e, flen, f, h)                                     */
+/*    expansion_sum_zeroelim1(elen, e, flen, f, h)                           */
+/*    expansion_sum_zeroelim2(elen, e, flen, f, h)                           */
+/*    fast_expansion_sum(elen, e, flen, f, h)                                */
+/*    fast_expansion_sum_zeroelim(elen, e, flen, f, h)                       */
+/*    linear_expansion_sum(elen, e, flen, f, h)                              */
+/*    linear_expansion_sum_zeroelim(elen, e, flen, f, h)                     */
+/*    scale_expansion(elen, e, b, h)                                         */
+/*    scale_expansion_zeroelim(elen, e, b, h)                                */
+/*    compress(elen, e, h)                                                   */
+/*                                                                           */
+/*  All of these are described in the long version of the paper; some are    */
+/*    described in the short version.  All return an integer that is the     */
+/*    length of h.  Those with suffix _zeroelim perform zero elimination,    */
+/*    and are recommended over their counterparts.  The procedure            */
+/*    fast_expansion_sum_zeroelim() (or linear_expansion_sum_zeroelim() on   */
+/*    processors that do not use the round-to-even tiebreaking rule) is      */
+/*    recommended over expansion_sum_zeroelim().  Each procedure has a       */
+/*    little note next to it (in the code below) that tells you whether or   */
+/*    not the output expansion may be the same array as one of the input     */
+/*    expansions.                                                            */
+/*                                                                           */
+/*                                                                           */
+/*  If you look around below, you'll also find macros for a bunch of         */
+/*    simple unrolled arithmetic operations, and procedures for printing     */
+/*    expansions (commented out because they don't work with all C           */
+/*    compilers) and for generating random floating-point numbers whose      */
+/*    significand bits are all random.  Most of the macros have undocumented */
+/*    requirements that certain of their parameters should not be the same   */
+/*    variable; for safety, better to make sure all the parameters are       */
+/*    distinct variables.  Feel free to send email to jrs@xxxxxxxxxx if you  */
+/*    have questions.                                                        */
+/*                                                                           */
+/*****************************************************************************/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include "predicates.h"
+
+/* Use header file generated automatically by predicates_init. */
+//#define USE_PREDICATES_INIT
+
+#ifdef USE_PREDICATES_INIT
+#include "predicates_init.h"
+#endif /* USE_PREDICATES_INIT */
+
+/* FPU control. We MUST have only double precision (not extended precision) */
+#include "rounding.h"
+
+/* On some machines, the exact arithmetic routines might be defeated by the  */
+/*   use of internal extended precision floating-point registers.  Sometimes */
+/*   this problem can be fixed by defining certain values to be volatile,    */
+/*   thus forcing them to be stored to memory and rounded off.  This isn't   */
+/*   a great solution, though, as it slows the arithmetic down.              */
+/*                                                                           */
+/* To try this out, write "#define INEXACT volatile" below.  Normally,       */
+/*   however, INEXACT should be defined to be nothing.  ("#define INEXACT".) */
+
+#define INEXACT                          /* Nothing */
+/* #define INEXACT volatile */
+
+#define REAL double                      /* float or double */
+#define REALPRINT doubleprint
+#define REALRAND doublerand
+#define NARROWRAND narrowdoublerand
+#define UNIFORMRAND uniformdoublerand
+
+/* Which of the following two methods of finding the absolute values is      */
+/*   fastest is compiler-dependent.  A few compilers can inline and optimize */
+/*   the fabs() call; but most will incur the overhead of a function call,   */
+/*   which is disastrously slow.  A faster way on IEEE machines might be to  */
+/*   mask the appropriate bit, but that's difficult to do in C.              */
+
+#define Absolute(a)  ((a) >= 0.0 ? (a) : -(a))
+/* #define Absolute(a)  fabs(a) */
+
+/* Many of the operations are broken up into two pieces, a main part that    */
+/*   performs an approximate operation, and a "tail" that computes the       */
+/*   roundoff error of that operation.                                       */
+/*                                                                           */
+/* The operations Fast_Two_Sum(), Fast_Two_Diff(), Two_Sum(), Two_Diff(),    */
+/*   Split(), and Two_Product() are all implemented as described in the      */
+/*   reference.  Each of these macros requires certain variables to be       */
+/*   defined in the calling routine.  The variables `bvirt', `c', `abig',    */
+/*   `_i', `_j', `_k', `_l', `_m', and `_n' are declared `INEXACT' because   */
+/*   they store the result of an operation that may incur roundoff error.    */
+/*   The input parameter `x' (or the highest numbered `x_' parameter) must   */
+/*   also be declared `INEXACT'.                                             */
+
+#define Fast_Two_Sum_Tail(a, b, x, y) \
+  bvirt = x - a; \
+  y = b - bvirt
+
+#define Fast_Two_Sum(a, b, x, y) \
+  x = (REAL) (a + b); \
+  Fast_Two_Sum_Tail(a, b, x, y)
+
+#define Fast_Two_Diff_Tail(a, b, x, y) \
+  bvirt = a - x; \
+  y = bvirt - b
+
+#define Fast_Two_Diff(a, b, x, y) \
+  x = (REAL) (a - b); \
+  Fast_Two_Diff_Tail(a, b, x, y)
+
+#define Two_Sum_Tail(a, b, x, y) \
+  bvirt = (REAL) (x - a); \
+  avirt = x - bvirt; \
+  bround = b - bvirt; \
+  around = a - avirt; \
+  y = around + bround
+
+#define Two_Sum(a, b, x, y) \
+  x = (REAL) (a + b); \
+  Two_Sum_Tail(a, b, x, y)
+
+#define Two_Diff_Tail(a, b, x, y) \
+  bvirt = (REAL) (a - x); \
+  avirt = x + bvirt; \
+  bround = bvirt - b; \
+  around = a - avirt; \
+  y = around + bround
+
+#define Two_Diff(a, b, x, y) \
+  x = (REAL) (a - b); \
+  Two_Diff_Tail(a, b, x, y)
+
+#define Split(a, ahi, alo) \
+  c = (REAL) (splitter * a); \
+  abig = (REAL) (c - a); \
+  ahi = c - abig; \
+  alo = a - ahi
+
+#define Two_Product_Tail(a, b, x, y) \
+  Split(a, ahi, alo); \
+  Split(b, bhi, blo); \
+  err1 = x - (ahi * bhi); \
+  err2 = err1 - (alo * bhi); \
+  err3 = err2 - (ahi * blo); \
+  y = (alo * blo) - err3
+
+#define Two_Product(a, b, x, y) \
+  x = (REAL) (a * b); \
+  Two_Product_Tail(a, b, x, y)
+
+/* Two_Product_Presplit() is Two_Product() where one of the inputs has       */
+/*   already been split.  Avoids redundant splitting.                        */
+
+#define Two_Product_Presplit(a, b, bhi, blo, x, y) \
+  x = (REAL) (a * b); \
+  Split(a, ahi, alo); \
+  err1 = x - (ahi * bhi); \
+  err2 = err1 - (alo * bhi); \
+  err3 = err2 - (ahi * blo); \
+  y = (alo * blo) - err3
+
+/* Two_Product_2Presplit() is Two_Product() where both of the inputs have    */
+/*   already been split.  Avoids redundant splitting.                        */
+
+#define Two_Product_2Presplit(a, ahi, alo, b, bhi, blo, x, y) \
+  x = (REAL) (a * b); \
+  err1 = x - (ahi * bhi); \
+  err2 = err1 - (alo * bhi); \
+  err3 = err2 - (ahi * blo); \
+  y = (alo * blo) - err3
+
+/* Square() can be done more quickly than Two_Product().                     */
+
+#define Square_Tail(a, x, y) \
+  Split(a, ahi, alo); \
+  err1 = x - (ahi * ahi); \
+  err3 = err1 - ((ahi + ahi) * alo); \
+  y = (alo * alo) - err3
+
+#define Square(a, x, y) \
+  x = (REAL) (a * a); \
+  Square_Tail(a, x, y)
+
+/* Macros for summing expansions of various fixed lengths.  These are all    */
+/*   unrolled versions of Expansion_Sum().                                   */
+
+#define Two_One_Sum(a1, a0, b, x2, x1, x0) \
+  Two_Sum(a0, b , _i, x0); \
+  Two_Sum(a1, _i, x2, x1)
+
+#define Two_One_Diff(a1, a0, b, x2, x1, x0) \
+  Two_Diff(a0, b , _i, x0); \
+  Two_Sum( a1, _i, x2, x1)
+
+#define Two_Two_Sum(a1, a0, b1, b0, x3, x2, x1, x0) \
+  Two_One_Sum(a1, a0, b0, _j, _0, x0); \
+  Two_One_Sum(_j, _0, b1, x3, x2, x1)
+
+#define Two_Two_Diff(a1, a0, b1, b0, x3, x2, x1, x0) \
+  Two_One_Diff(a1, a0, b0, _j, _0, x0); \
+  Two_One_Diff(_j, _0, b1, x3, x2, x1)
+
+#define Four_One_Sum(a3, a2, a1, a0, b, x4, x3, x2, x1, x0) \
+  Two_One_Sum(a1, a0, b , _j, x1, x0); \
+  Two_One_Sum(a3, a2, _j, x4, x3, x2)
+
+#define Four_Two_Sum(a3, a2, a1, a0, b1, b0, x5, x4, x3, x2, x1, x0) \
+  Four_One_Sum(a3, a2, a1, a0, b0, _k, _2, _1, _0, x0); \
+  Four_One_Sum(_k, _2, _1, _0, b1, x5, x4, x3, x2, x1)
+
+#define Four_Four_Sum(a3, a2, a1, a0, b4, b3, b1, b0, x7, x6, x5, x4, x3, x2, \
+                      x1, x0) \
+  Four_Two_Sum(a3, a2, a1, a0, b1, b0, _l, _2, _1, _0, x1, x0); \
+  Four_Two_Sum(_l, _2, _1, _0, b4, b3, x7, x6, x5, x4, x3, x2)
+
+#define Eight_One_Sum(a7, a6, a5, a4, a3, a2, a1, a0, b, x8, x7, x6, x5, x4, \
+                      x3, x2, x1, x0) \
+  Four_One_Sum(a3, a2, a1, a0, b , _j, x3, x2, x1, x0); \
+  Four_One_Sum(a7, a6, a5, a4, _j, x8, x7, x6, x5, x4)
+
+#define Eight_Two_Sum(a7, a6, a5, a4, a3, a2, a1, a0, b1, b0, x9, x8, x7, \
+                      x6, x5, x4, x3, x2, x1, x0) \
+  Eight_One_Sum(a7, a6, a5, a4, a3, a2, a1, a0, b0, _k, _6, _5, _4, _3, _2, \
+                _1, _0, x0); \
+  Eight_One_Sum(_k, _6, _5, _4, _3, _2, _1, _0, b1, x9, x8, x7, x6, x5, x4, \
+                x3, x2, x1)
+
+#define Eight_Four_Sum(a7, a6, a5, a4, a3, a2, a1, a0, b4, b3, b1, b0, x11, \
+                       x10, x9, x8, x7, x6, x5, x4, x3, x2, x1, x0) \
+  Eight_Two_Sum(a7, a6, a5, a4, a3, a2, a1, a0, b1, b0, _l, _6, _5, _4, _3, \
+                _2, _1, _0, x1, x0); \
+  Eight_Two_Sum(_l, _6, _5, _4, _3, _2, _1, _0, b4, b3, x11, x10, x9, x8, \
+                x7, x6, x5, x4, x3, x2)
+
+/* Macros for multiplying expansions of various fixed lengths.               */
+
+#define Two_One_Product(a1, a0, b, x3, x2, x1, x0) \
+  Split(b, bhi, blo); \
+  Two_Product_Presplit(a0, b, bhi, blo, _i, x0); \
+  Two_Product_Presplit(a1, b, bhi, blo, _j, _0); \
+  Two_Sum(_i, _0, _k, x1); \
+  Fast_Two_Sum(_j, _k, x3, x2)
+
+#define Four_One_Product(a3, a2, a1, a0, b, x7, x6, x5, x4, x3, x2, x1, x0) \
+  Split(b, bhi, blo); \
+  Two_Product_Presplit(a0, b, bhi, blo, _i, x0); \
+  Two_Product_Presplit(a1, b, bhi, blo, _j, _0); \
+  Two_Sum(_i, _0, _k, x1); \
+  Fast_Two_Sum(_j, _k, _i, x2); \
+  Two_Product_Presplit(a2, b, bhi, blo, _j, _0); \
+  Two_Sum(_i, _0, _k, x3); \
+  Fast_Two_Sum(_j, _k, _i, x4); \
+  Two_Product_Presplit(a3, b, bhi, blo, _j, _0); \
+  Two_Sum(_i, _0, _k, x5); \
+  Fast_Two_Sum(_j, _k, x7, x6)
+
+#define Two_Two_Product(a1, a0, b1, b0, x7, x6, x5, x4, x3, x2, x1, x0) \
+  Split(a0, a0hi, a0lo); \
+  Split(b0, bhi, blo); \
+  Two_Product_2Presplit(a0, a0hi, a0lo, b0, bhi, blo, _i, x0); \
+  Split(a1, a1hi, a1lo); \
+  Two_Product_2Presplit(a1, a1hi, a1lo, b0, bhi, blo, _j, _0); \
+  Two_Sum(_i, _0, _k, _1); \
+  Fast_Two_Sum(_j, _k, _l, _2); \
+  Split(b1, bhi, blo); \
+  Two_Product_2Presplit(a0, a0hi, a0lo, b1, bhi, blo, _i, _0); \
+  Two_Sum(_1, _0, _k, x1); \
+  Two_Sum(_2, _k, _j, _1); \
+  Two_Sum(_l, _j, _m, _2); \
+  Two_Product_2Presplit(a1, a1hi, a1lo, b1, bhi, blo, _j, _0); \
+  Two_Sum(_i, _0, _n, _0); \
+  Two_Sum(_1, _0, _i, x2); \
+  Two_Sum(_2, _i, _k, _1); \
+  Two_Sum(_m, _k, _l, _2); \
+  Two_Sum(_j, _n, _k, _0); \
+  Two_Sum(_1, _0, _j, x3); \
+  Two_Sum(_2, _j, _i, _1); \
+  Two_Sum(_l, _i, _m, _2); \
+  Two_Sum(_1, _k, _i, x4); \
+  Two_Sum(_2, _i, _k, x5); \
+  Two_Sum(_m, _k, x7, x6)
+
+/* An expansion of length two can be squared more quickly than finding the   */
+/*   product of two different expansions of length two, and the result is    */
+/*   guaranteed to have no more than six (rather than eight) components.     */
+
+#define Two_Square(a1, a0, x5, x4, x3, x2, x1, x0) \
+  Square(a0, _j, x0); \
+  _0 = a0 + a0; \
+  Two_Product(a1, _0, _k, _1); \
+  Two_One_Sum(_k, _1, _j, _l, _2, x1); \
+  Square(a1, _j, _1); \
+  Two_Two_Sum(_j, _1, _l, _2, x5, x4, x3, x2)
+
+#ifndef USE_PREDICATES_INIT
+
+static REAL splitter;     /* = 2^ceiling(p / 2) + 1.  Used to split floats in half. */
+/* A set of coefficients used to calculate maximum roundoff errors.          */
+static REAL resulterrbound;
+static REAL ccwerrboundA, ccwerrboundB, ccwerrboundC;
+static REAL o3derrboundA, o3derrboundB, o3derrboundC;
+static REAL iccerrboundA, iccerrboundB, iccerrboundC;
+static REAL isperrboundA, isperrboundB, isperrboundC;
+
+void 
+gts_predicates_init()
+{
+  double half = 0.5;
+  double check = 1.0, lastcheck;
+  int every_other = 1;
+  /* epsilon = 2^(-p).  Used to estimate roundoff errors. */
+  double epsilon = 1.0;   
+
+  FPU_ROUND_DOUBLE;
+
+  splitter = 1.;
+
+  /* Repeatedly divide `epsilon' by two until it is too small to add to   */
+  /* one without causing roundoff.  (Also check if the sum is equal to    */
+  /* the previous sum, for machines that round up instead of using exact  */
+  /* rounding.  Not that this library will work on such machines anyway). */
+  do {
+    lastcheck = check;
+    epsilon *= half;
+    if (every_other) {
+      splitter *= 2.0;
+    }
+    every_other = !every_other;
+    check = 1.0 + epsilon;
+  } while ((check != 1.0) && (check != lastcheck));
+  splitter += 1.0;
+  /* Error bounds for orientation and incircle tests. */
+  resulterrbound = (3.0 + 8.0 * epsilon) * epsilon;
+  ccwerrboundA = (3.0 + 16.0 * epsilon) * epsilon;
+  ccwerrboundB = (2.0 + 12.0 * epsilon) * epsilon;
+  ccwerrboundC = (9.0 + 64.0 * epsilon) * epsilon * epsilon;
+  o3derrboundA = (7.0 + 56.0 * epsilon) * epsilon;
+  o3derrboundB = (3.0 + 28.0 * epsilon) * epsilon;
+  o3derrboundC = (26.0 + 288.0 * epsilon) * epsilon * epsilon;
+  iccerrboundA = (10.0 + 96.0 * epsilon) * epsilon;
+  iccerrboundB = (4.0 + 48.0 * epsilon) * epsilon;
+  iccerrboundC = (44.0 + 576.0 * epsilon) * epsilon * epsilon;
+  isperrboundA = (16.0 + 224.0 * epsilon) * epsilon;
+  isperrboundB = (5.0 + 72.0 * epsilon) * epsilon;
+  isperrboundC = (71.0 + 1408.0 * epsilon) * epsilon * epsilon;
+
+
+  FPU_RESTORE;
+}
+
+#endif /* USE_PREDICATES_INIT */
+
+/*****************************************************************************/
+/*                                                                           */
+/*  doubleprint()   Print the bit representation of a double.                */
+/*                                                                           */
+/*  Useful for debugging exact arithmetic routines.                          */
+/*                                                                           */
+/*****************************************************************************/
+
+/*
+void doubleprint(number)
+double number;
+{
+  unsigned long long no;
+  unsigned long long sign, expo;
+  int exponent;
+  int i, bottomi;
+
+  no = *(unsigned long long *) &number;
+  sign = no & 0x8000000000000000ll;
+  expo = (no >> 52) & 0x7ffll;
+  exponent = (int) expo;
+  exponent = exponent - 1023;
+  if (sign) {
+    printf("-");
+  } else {
+    printf(" ");
+  }
+  if (exponent == -1023) {
+    printf(
+      "0.0000000000000000000000000000000000000000000000000000_     (   )");
+  } else {
+    printf("1.");
+    bottomi = -1;
+    for (i = 0; i < 52; i++) {
+      if (no & 0x0008000000000000ll) {
+        printf("1");
+        bottomi = i;
+      } else {
+        printf("0");
+      }
+      no <<= 1;
+    }
+    printf("_%d  (%d)", exponent, exponent - 1 - bottomi);
+  }
+}
+*/
+
+/*****************************************************************************/
+/*                                                                           */
+/*  floatprint()   Print the bit representation of a float.                  */
+/*                                                                           */
+/*  Useful for debugging exact arithmetic routines.                          */
+/*                                                                           */
+/*****************************************************************************/
+
+/*
+void floatprint(number)
+float number;
+{
+  unsigned no;
+  unsigned sign, expo;
+  int exponent;
+  int i, bottomi;
+
+  no = *(unsigned *) &number;
+  sign = no & 0x80000000;
+  expo = (no >> 23) & 0xff;
+  exponent = (int) expo;
+  exponent = exponent - 127;
+  if (sign) {
+    printf("-");
+  } else {
+    printf(" ");
+  }
+  if (exponent == -127) {
+    printf("0.00000000000000000000000_     (   )");
+  } else {
+    printf("1.");
+    bottomi = -1;
+    for (i = 0; i < 23; i++) {
+      if (no & 0x00400000) {
+        printf("1");
+        bottomi = i;
+      } else {
+        printf("0");
+      }
+      no <<= 1;
+    }
+    printf("_%3d  (%3d)", exponent, exponent - 1 - bottomi);
+  }
+}
+*/
+
+/*****************************************************************************/
+/*                                                                           */
+/*  expansion_print()   Print the bit representation of an expansion.        */
+/*                                                                           */
+/*  Useful for debugging exact arithmetic routines.                          */
+/*                                                                           */
+/*****************************************************************************/
+
+/*
+void expansion_print(elen, e)
+int elen;
+REAL *e;
+{
+  int i;
+
+  for (i = elen - 1; i >= 0; i--) {
+    REALPRINT(e[i]);
+    if (i > 0) {
+      printf(" +\n");
+    } else {
+      printf("\n");
+    }
+  }
+}
+*/
+
+/*****************************************************************************/
+/*                                                                           */
+/*  doublerand()   Generate a double with random 53-bit significand and a    */
+/*                 random exponent in [0, 511].                              */
+/*                                                                           */
+/*****************************************************************************/
+
+/*
+static double doublerand()
+{
+  double result;
+  double expo;
+  long a, b, c;
+  long i;
+
+  a = random();
+  b = random();
+  c = random();
+  result = (double) (a - 1073741824) * 8388608.0 + (double) (b >> 8);
+  for (i = 512, expo = 2; i <= 131072; i *= 2, expo = expo * expo) {
+    if (c & i) {
+      result *= expo;
+    }
+  }
+  return result;
+}
+*/
+
+/*****************************************************************************/
+/*                                                                           */
+/*  narrowdoublerand()   Generate a double with random 53-bit significand    */
+/*                       and a random exponent in [0, 7].                    */
+/*                                                                           */
+/*****************************************************************************/
+
+/*
+static double narrowdoublerand()
+{
+  double result;
+  double expo;
+  long a, b, c;
+  long i;
+
+  a = random();
+  b = random();
+  c = random();
+  result = (double) (a - 1073741824) * 8388608.0 + (double) (b >> 8);
+  for (i = 512, expo = 2; i <= 2048; i *= 2, expo = expo * expo) {
+    if (c & i) {
+      result *= expo;
+    }
+  }
+  return result;
+}
+*/
+
+/*****************************************************************************/
+/*                                                                           */
+/*  uniformdoublerand()   Generate a double with random 53-bit significand.  */
+/*                                                                           */
+/*****************************************************************************/
+
+/*
+static double uniformdoublerand()
+{
+  double result;
+  long a, b;
+
+  a = random();
+  b = random();
+  result = (double) (a - 1073741824) * 8388608.0 + (double) (b >> 8);
+  return result;
+}
+*/
+
+/*****************************************************************************/
+/*                                                                           */
+/*  floatrand()   Generate a float with random 24-bit significand and a      */
+/*                random exponent in [0, 63].                                */
+/*                                                                           */
+/*****************************************************************************/
+
+/*
+static float floatrand()
+{
+  float result;
+  float expo;
+  long a, c;
+  long i;
+
+  a = random();
+  c = random();
+  result = (float) ((a - 1073741824) >> 6);
+  for (i = 512, expo = 2; i <= 16384; i *= 2, expo = expo * expo) {
+    if (c & i) {
+      result *= expo;
+    }
+  }
+  return result;
+}
+*/
+
+/*****************************************************************************/
+/*                                                                           */
+/*  narrowfloatrand()   Generate a float with random 24-bit significand and  */
+/*                      a random exponent in [0, 7].                         */
+/*                                                                           */
+/*****************************************************************************/
+
+/*
+static float narrowfloatrand()
+{
+  float result;
+  float expo;
+  long a, c;
+  long i;
+
+  a = random();
+  c = random();
+  result = (float) ((a - 1073741824) >> 6);
+  for (i = 512, expo = 2; i <= 2048; i *= 2, expo = expo * expo) {
+    if (c & i) {
+      result *= expo;
+    }
+  }
+  return result;
+}
+*/
+
+/*****************************************************************************/
+/*                                                                           */
+/*  uniformfloatrand()   Generate a float with random 24-bit significand.    */
+/*                                                                           */
+/*****************************************************************************/
+
+/*
+static float uniformfloatrand()
+{
+  float result;
+  long a;
+
+  a = random();
+  result = (float) ((a - 1073741824) >> 6);
+  return result;
+}
+*/
+
+/*****************************************************************************/
+/*                                                                           */
+/*  fast_expansion_sum_zeroelim()   Sum two expansions, eliminating zero     */
+/*                                  components from the output expansion.    */
+/*                                                                           */
+/*  Sets h = e + f.  See the long version of my paper for details.           */
+/*                                                                           */
+/*  If round-to-even is used (as with IEEE 754), maintains the strongly      */
+/*  nonoverlapping property.  (That is, if e is strongly nonoverlapping, h   */
+/*  will be also.)  Does NOT maintain the nonoverlapping or nonadjacent      */
+/*  properties.                                                              */
+/*                                                                           */
+/*****************************************************************************/
+
+static int fast_expansion_sum_zeroelim(int elen, REAL *e, 
+				       int flen, REAL *f, REAL *h)
+     /* h cannot be e or f. */
+{
+  REAL Q;
+  INEXACT REAL Qnew;
+  INEXACT REAL hh;
+  INEXACT REAL bvirt;
+  REAL avirt, bround, around;
+  int eindex, findex, hindex;
+  REAL enow, fnow;
+
+  enow = e[0];
+  fnow = f[0];
+  eindex = findex = 0;
+  if ((fnow > enow) == (fnow > -enow)) {
+    Q = enow;
+    enow = e[++eindex];
+  } else {
+    Q = fnow;
+    fnow = f[++findex];
+  }
+  hindex = 0;
+  if ((eindex < elen) && (findex < flen)) {
+    if ((fnow > enow) == (fnow > -enow)) {
+      Fast_Two_Sum(enow, Q, Qnew, hh);
+      enow = e[++eindex];
+    } else {
+      Fast_Two_Sum(fnow, Q, Qnew, hh);
+      fnow = f[++findex];
+    }
+    Q = Qnew;
+    if (hh != 0.0) {
+      h[hindex++] = hh;
+    }
+    while ((eindex < elen) && (findex < flen)) {
+      if ((fnow > enow) == (fnow > -enow)) {
+        Two_Sum(Q, enow, Qnew, hh);
+        enow = e[++eindex];
+      } else {
+        Two_Sum(Q, fnow, Qnew, hh);
+        fnow = f[++findex];
+      }
+      Q = Qnew;
+      if (hh != 0.0) {
+        h[hindex++] = hh;
+      }
+    }
+  }
+  while (eindex < elen) {
+    Two_Sum(Q, enow, Qnew, hh);
+    enow = e[++eindex];
+    Q = Qnew;
+    if (hh != 0.0) {
+      h[hindex++] = hh;
+    }
+  }
+  while (findex < flen) {
+    Two_Sum(Q, fnow, Qnew, hh);
+    fnow = f[++findex];
+    Q = Qnew;
+    if (hh != 0.0) {
+      h[hindex++] = hh;
+    }
+  }
+  if ((Q != 0.0) || (hindex == 0)) {
+    h[hindex++] = Q;
+  }
+  return hindex;
+}
+
+/*****************************************************************************/
+/*                                                                           */
+/*  scale_expansion_zeroelim()   Multiply an expansion by a scalar,          */
+/*                               eliminating zero components from the        */
+/*                               output expansion.                           */
+/*                                                                           */
+/*  Sets h = be.  See either version of my paper for details.                */
+/*                                                                           */
+/*  Maintains the nonoverlapping property.  If round-to-even is used (as     */
+/*  with IEEE 754), maintains the strongly nonoverlapping and nonadjacent    */
+/*  properties as well.  (That is, if e has one of these properties, so      */
+/*  will h.)                                                                 */
+/*                                                                           */
+/*****************************************************************************/
+
+static int scale_expansion_zeroelim(int elen, REAL *e, REAL b, REAL *h)
+     /* e and h cannot be the same. */
+{
+  INEXACT REAL Q, sum;
+  REAL hh;
+  INEXACT REAL product1;
+  REAL product0;
+  int eindex, hindex;
+  REAL enow;
+  INEXACT REAL bvirt;
+  REAL avirt, bround, around;
+  INEXACT REAL c;
+  INEXACT REAL abig;
+  REAL ahi, alo, bhi, blo;
+  REAL err1, err2, err3;
+
+  Split(b, bhi, blo);
+  Two_Product_Presplit(e[0], b, bhi, blo, Q, hh);
+  hindex = 0;
+  if (hh != 0) {
+    h[hindex++] = hh;
+  }
+  for (eindex = 1; eindex < elen; eindex++) {
+    enow = e[eindex];
+    Two_Product_Presplit(enow, b, bhi, blo, product1, product0);
+    Two_Sum(Q, product0, sum, hh);
+    if (hh != 0) {
+      h[hindex++] = hh;
+    }
+    Fast_Two_Sum(product1, sum, Q, hh);
+    if (hh != 0) {
+      h[hindex++] = hh;
+    }
+  }
+  if ((Q != 0.0) || (hindex == 0)) {
+    h[hindex++] = Q;
+  }
+  return hindex;
+}
+
+/*****************************************************************************/
+/*                                                                           */
+/*  estimate()   Produce a one-word estimate of an expansion's value.        */
+/*                                                                           */
+/*  See either version of my paper for details.                              */
+/*                                                                           */
+/*****************************************************************************/
+
+static REAL estimate(int elen, REAL *e)
+{
+  REAL Q;
+  int eindex;
+
+  Q = e[0];
+  for (eindex = 1; eindex < elen; eindex++) {
+    Q += e[eindex];
+  }
+  return Q;
+}
+
+/*****************************************************************************/
+/*                                                                           */
+/*  orient2dfast()   Approximate 2D orientation test.  Nonrobust.            */
+/*  orient2dexact()   Exact 2D orientation test.  Robust.                    */
+/*  orient2dslow()   Another exact 2D orientation test.  Robust.             */
+/*  orient2d()   Adaptive exact 2D orientation test.  Robust.                */
+/*                                                                           */
+/*               Return a positive value if the points pa, pb, and pc occur  */
+/*               in counterclockwise order; a negative value if they occur   */
+/*               in clockwise order; and zero if they are collinear.  The    */
+/*               result is also a rough approximation of twice the signed    */
+/*               area of the triangle defined by the three points.           */
+/*                                                                           */
+/*  Only the first and last routine should be used; the middle two are for   */
+/*  timings.                                                                 */
+/*                                                                           */
+/*  The last three use exact arithmetic to ensure a correct answer.  The     */
+/*  result returned is the determinant of a matrix.  In orient2d() only,     */
+/*  this determinant is computed adaptively, in the sense that exact         */
+/*  arithmetic is used only to the degree it is needed to ensure that the    */
+/*  returned value has the correct sign.  Hence, orient2d() is usually quite */
+/*  fast, but will run more slowly when the input points are collinear or    */
+/*  nearly so.                                                               */
+/*                                                                           */
+/*****************************************************************************/
+
+static REAL orient2dadapt(REAL *pa, REAL *pb, REAL *pc, REAL detsum)
+{
+  INEXACT REAL acx, acy, bcx, bcy;
+  REAL acxtail, acytail, bcxtail, bcytail;
+  INEXACT REAL detleft, detright;
+  REAL detlefttail, detrighttail;
+  REAL det, errbound;
+  REAL B[4], C1[8], C2[12], D[16];
+  INEXACT REAL B3;
+  int C1length, C2length, Dlength;
+  REAL u[4];
+  INEXACT REAL u3;
+  INEXACT REAL s1, t1;
+  REAL s0, t0;
+
+  INEXACT REAL bvirt;
+  REAL avirt, bround, around;
+  INEXACT REAL c;
+  INEXACT REAL abig;
+  REAL ahi, alo, bhi, blo;
+  REAL err1, err2, err3;
+  INEXACT REAL _i, _j;
+  REAL _0;
+
+  acx = (REAL) (pa[0] - pc[0]);
+  bcx = (REAL) (pb[0] - pc[0]);
+  acy = (REAL) (pa[1] - pc[1]);
+  bcy = (REAL) (pb[1] - pc[1]);
+
+  Two_Product(acx, bcy, detleft, detlefttail);
+  Two_Product(acy, bcx, detright, detrighttail);
+
+  Two_Two_Diff(detleft, detlefttail, detright, detrighttail,
+               B3, B[2], B[1], B[0]);
+  B[3] = B3;
+
+  det = estimate(4, B);
+  errbound = ccwerrboundB * detsum;
+  if ((det >= errbound) || (-det >= errbound)) {
+    return det;
+  }
+
+  Two_Diff_Tail(pa[0], pc[0], acx, acxtail);
+  Two_Diff_Tail(pb[0], pc[0], bcx, bcxtail);
+  Two_Diff_Tail(pa[1], pc[1], acy, acytail);
+  Two_Diff_Tail(pb[1], pc[1], bcy, bcytail);
+
+  if ((acxtail == 0.0) && (acytail == 0.0)
+      && (bcxtail == 0.0) && (bcytail == 0.0)) {
+    return det;
+  }
+
+  errbound = ccwerrboundC * detsum + resulterrbound * Absolute(det);
+  det += (acx * bcytail + bcy * acxtail)
+       - (acy * bcxtail + bcx * acytail);
+  if ((det >= errbound) || (-det >= errbound)) {
+    return det;
+  }
+
+  Two_Product(acxtail, bcy, s1, s0);
+  Two_Product(acytail, bcx, t1, t0);
+  Two_Two_Diff(s1, s0, t1, t0, u3, u[2], u[1], u[0]);
+  u[3] = u3;
+  C1length = fast_expansion_sum_zeroelim(4, B, 4, u, C1);
+
+  Two_Product(acx, bcytail, s1, s0);
+  Two_Product(acy, bcxtail, t1, t0);
+  Two_Two_Diff(s1, s0, t1, t0, u3, u[2], u[1], u[0]);
+  u[3] = u3;
+  C2length = fast_expansion_sum_zeroelim(C1length, C1, 4, u, C2);
+
+  Two_Product(acxtail, bcytail, s1, s0);
+  Two_Product(acytail, bcxtail, t1, t0);
+  Two_Two_Diff(s1, s0, t1, t0, u3, u[2], u[1], u[0]);
+  u[3] = u3;
+  Dlength = fast_expansion_sum_zeroelim(C2length, C2, 4, u, D);
+
+  return(D[Dlength - 1]);
+}
+
+REAL orient2d(pa, pb, pc)
+REAL *pa;
+REAL *pb;
+REAL *pc;
+{
+  REAL detleft, detright, det;
+  REAL detsum, errbound;
+  REAL orient;
+
+  FPU_ROUND_DOUBLE;
+
+  detleft = (pa[0] - pc[0]) * (pb[1] - pc[1]);
+  detright = (pa[1] - pc[1]) * (pb[0] - pc[0]);
+  det = detleft - detright;
+
+  if (detleft > 0.0) {
+    if (detright <= 0.0) {
+      FPU_RESTORE;
+      return det;
+    } else {
+      detsum = detleft + detright;
+    }
+  } else if (detleft < 0.0) {
+    if (detright >= 0.0) {
+      FPU_RESTORE;
+      return det;
+    } else {
+      detsum = -detleft - detright;
+    }
+  } else {
+    FPU_RESTORE;
+    return det;
+  }
+
+  errbound = ccwerrboundA * detsum;
+  if ((det >= errbound) || (-det >= errbound)) {
+    FPU_RESTORE;
+    return det;
+  }
+
+  orient = orient2dadapt(pa, pb, pc, detsum);
+  FPU_RESTORE;
+  return orient;
+}
+
+/*****************************************************************************/
+/*                                                                           */
+/*  orient3dfast()   Approximate 3D orientation test.  Nonrobust.            */
+/*  orient3dexact()   Exact 3D orientation test.  Robust.                    */
+/*  orient3dslow()   Another exact 3D orientation test.  Robust.             */
+/*  orient3d()   Adaptive exact 3D orientation test.  Robust.                */
+/*                                                                           */
+/*               Return a positive value if the point pd lies below the      */
+/*               plane passing through pa, pb, and pc; "below" is defined so */
+/*               that pa, pb, and pc appear in counterclockwise order when   */
+/*               viewed from above the plane.  Returns a negative value if   */
+/*               pd lies above the plane.  Returns zero if the points are    */
+/*               coplanar.  The result is also a rough approximation of six  */
+/*               times the signed volume of the tetrahedron defined by the   */
+/*               four points.                                                */
+/*                                                                           */
+/*  Only the first and last routine should be used; the middle two are for   */
+/*  timings.                                                                 */
+/*                                                                           */
+/*  The last three use exact arithmetic to ensure a correct answer.  The     */
+/*  result returned is the determinant of a matrix.  In orient3d() only,     */
+/*  this determinant is computed adaptively, in the sense that exact         */
+/*  arithmetic is used only to the degree it is needed to ensure that the    */
+/*  returned value has the correct sign.  Hence, orient3d() is usually quite */
+/*  fast, but will run more slowly when the input points are coplanar or     */
+/*  nearly so.                                                               */
+/*                                                                           */
+/*****************************************************************************/
+
+static REAL orient3dadapt(REAL *pa, REAL *pb, REAL *pc, REAL *pd, 
+			  REAL permanent)
+{
+  INEXACT REAL adx, bdx, cdx, ady, bdy, cdy, adz, bdz, cdz;
+  REAL det, errbound;
+
+  INEXACT REAL bdxcdy1, cdxbdy1, cdxady1, adxcdy1, adxbdy1, bdxady1;
+  REAL bdxcdy0, cdxbdy0, cdxady0, adxcdy0, adxbdy0, bdxady0;
+  REAL bc[4], ca[4], ab[4];
+  INEXACT REAL bc3, ca3, ab3;
+  REAL adet[8], bdet[8], cdet[8];
+  int alen, blen, clen;
+  REAL abdet[16];
+  int ablen;
+  REAL *finnow, *finother, *finswap;
+  REAL fin1[192], fin2[192];
+  int finlength;
+
+  REAL adxtail, bdxtail, cdxtail;
+  REAL adytail, bdytail, cdytail;
+  REAL adztail, bdztail, cdztail;
+  INEXACT REAL at_blarge, at_clarge;
+  INEXACT REAL bt_clarge, bt_alarge;
+  INEXACT REAL ct_alarge, ct_blarge;
+  REAL at_b[4], at_c[4], bt_c[4], bt_a[4], ct_a[4], ct_b[4];
+  int at_blen, at_clen, bt_clen, bt_alen, ct_alen, ct_blen;
+  INEXACT REAL bdxt_cdy1, cdxt_bdy1, cdxt_ady1;
+  INEXACT REAL adxt_cdy1, adxt_bdy1, bdxt_ady1;
+  REAL bdxt_cdy0, cdxt_bdy0, cdxt_ady0;
+  REAL adxt_cdy0, adxt_bdy0, bdxt_ady0;
+  INEXACT REAL bdyt_cdx1, cdyt_bdx1, cdyt_adx1;
+  INEXACT REAL adyt_cdx1, adyt_bdx1, bdyt_adx1;
+  REAL bdyt_cdx0, cdyt_bdx0, cdyt_adx0;
+  REAL adyt_cdx0, adyt_bdx0, bdyt_adx0;
+  REAL bct[8], cat[8], abt[8];
+  int bctlen, catlen, abtlen;
+  INEXACT REAL bdxt_cdyt1, cdxt_bdyt1, cdxt_adyt1;
+  INEXACT REAL adxt_cdyt1, adxt_bdyt1, bdxt_adyt1;
+  REAL bdxt_cdyt0, cdxt_bdyt0, cdxt_adyt0;
+  REAL adxt_cdyt0, adxt_bdyt0, bdxt_adyt0;
+  REAL u[4], v[12], w[16];
+  INEXACT REAL u3;
+  int vlength, wlength;
+  REAL negate;
+
+  INEXACT REAL bvirt;
+  REAL avirt, bround, around;
+  INEXACT REAL c;
+  INEXACT REAL abig;
+  REAL ahi, alo, bhi, blo;
+  REAL err1, err2, err3;
+  INEXACT REAL _i, _j, _k;
+  REAL _0;
+
+  adx = (REAL) (pa[0] - pd[0]);
+  bdx = (REAL) (pb[0] - pd[0]);
+  cdx = (REAL) (pc[0] - pd[0]);
+  ady = (REAL) (pa[1] - pd[1]);
+  bdy = (REAL) (pb[1] - pd[1]);
+  cdy = (REAL) (pc[1] - pd[1]);
+  adz = (REAL) (pa[2] - pd[2]);
+  bdz = (REAL) (pb[2] - pd[2]);
+  cdz = (REAL) (pc[2] - pd[2]);
+
+  Two_Product(bdx, cdy, bdxcdy1, bdxcdy0);
+  Two_Product(cdx, bdy, cdxbdy1, cdxbdy0);
+  Two_Two_Diff(bdxcdy1, bdxcdy0, cdxbdy1, cdxbdy0, bc3, bc[2], bc[1], bc[0]);
+  bc[3] = bc3;
+  alen = scale_expansion_zeroelim(4, bc, adz, adet);
+
+  Two_Product(cdx, ady, cdxady1, cdxady0);
+  Two_Product(adx, cdy, adxcdy1, adxcdy0);
+  Two_Two_Diff(cdxady1, cdxady0, adxcdy1, adxcdy0, ca3, ca[2], ca[1], ca[0]);
+  ca[3] = ca3;
+  blen = scale_expansion_zeroelim(4, ca, bdz, bdet);
+
+  Two_Product(adx, bdy, adxbdy1, adxbdy0);
+  Two_Product(bdx, ady, bdxady1, bdxady0);
+  Two_Two_Diff(adxbdy1, adxbdy0, bdxady1, bdxady0, ab3, ab[2], ab[1], ab[0]);
+  ab[3] = ab3;
+  clen = scale_expansion_zeroelim(4, ab, cdz, cdet);
+
+  ablen = fast_expansion_sum_zeroelim(alen, adet, blen, bdet, abdet);
+  finlength = fast_expansion_sum_zeroelim(ablen, abdet, clen, cdet, fin1);
+
+  det = estimate(finlength, fin1);
+  errbound = o3derrboundB * permanent;
+  if ((det >= errbound) || (-det >= errbound)) {
+    return det;
+  }
+
+  Two_Diff_Tail(pa[0], pd[0], adx, adxtail);
+  Two_Diff_Tail(pb[0], pd[0], bdx, bdxtail);
+  Two_Diff_Tail(pc[0], pd[0], cdx, cdxtail);
+  Two_Diff_Tail(pa[1], pd[1], ady, adytail);
+  Two_Diff_Tail(pb[1], pd[1], bdy, bdytail);
+  Two_Diff_Tail(pc[1], pd[1], cdy, cdytail);
+  Two_Diff_Tail(pa[2], pd[2], adz, adztail);
+  Two_Diff_Tail(pb[2], pd[2], bdz, bdztail);
+  Two_Diff_Tail(pc[2], pd[2], cdz, cdztail);
+
+  if ((adxtail == 0.0) && (bdxtail == 0.0) && (cdxtail == 0.0)
+      && (adytail == 0.0) && (bdytail == 0.0) && (cdytail == 0.0)
+      && (adztail == 0.0) && (bdztail == 0.0) && (cdztail == 0.0)) {
+    return det;
+  }
+
+  errbound = o3derrboundC * permanent + resulterrbound * Absolute(det);
+  det += (adz * ((bdx * cdytail + cdy * bdxtail)
+                 - (bdy * cdxtail + cdx * bdytail))
+          + adztail * (bdx * cdy - bdy * cdx))
+       + (bdz * ((cdx * adytail + ady * cdxtail)
+                 - (cdy * adxtail + adx * cdytail))
+          + bdztail * (cdx * ady - cdy * adx))
+       + (cdz * ((adx * bdytail + bdy * adxtail)
+                 - (ady * bdxtail + bdx * adytail))
+          + cdztail * (adx * bdy - ady * bdx));
+  if ((det >= errbound) || (-det >= errbound)) {
+    return det;
+  }
+
+  finnow = fin1;
+  finother = fin2;
+
+  if (adxtail == 0.0) {
+    if (adytail == 0.0) {
+      at_b[0] = 0.0;
+      at_blen = 1;
+      at_c[0] = 0.0;
+      at_clen = 1;
+    } else {
+      negate = -adytail;
+      Two_Product(negate, bdx, at_blarge, at_b[0]);
+      at_b[1] = at_blarge;
+      at_blen = 2;
+      Two_Product(adytail, cdx, at_clarge, at_c[0]);
+      at_c[1] = at_clarge;
+      at_clen = 2;
+    }
+  } else {
+    if (adytail == 0.0) {
+      Two_Product(adxtail, bdy, at_blarge, at_b[0]);
+      at_b[1] = at_blarge;
+      at_blen = 2;
+      negate = -adxtail;
+      Two_Product(negate, cdy, at_clarge, at_c[0]);
+      at_c[1] = at_clarge;
+      at_clen = 2;
+    } else {
+      Two_Product(adxtail, bdy, adxt_bdy1, adxt_bdy0);
+      Two_Product(adytail, bdx, adyt_bdx1, adyt_bdx0);
+      Two_Two_Diff(adxt_bdy1, adxt_bdy0, adyt_bdx1, adyt_bdx0,
+                   at_blarge, at_b[2], at_b[1], at_b[0]);
+      at_b[3] = at_blarge;
+      at_blen = 4;
+      Two_Product(adytail, cdx, adyt_cdx1, adyt_cdx0);
+      Two_Product(adxtail, cdy, adxt_cdy1, adxt_cdy0);
+      Two_Two_Diff(adyt_cdx1, adyt_cdx0, adxt_cdy1, adxt_cdy0,
+                   at_clarge, at_c[2], at_c[1], at_c[0]);
+      at_c[3] = at_clarge;
+      at_clen = 4;
+    }
+  }
+  if (bdxtail == 0.0) {
+    if (bdytail == 0.0) {
+      bt_c[0] = 0.0;
+      bt_clen = 1;
+      bt_a[0] = 0.0;
+      bt_alen = 1;
+    } else {
+      negate = -bdytail;
+      Two_Product(negate, cdx, bt_clarge, bt_c[0]);
+      bt_c[1] = bt_clarge;
+      bt_clen = 2;
+      Two_Product(bdytail, adx, bt_alarge, bt_a[0]);
+      bt_a[1] = bt_alarge;
+      bt_alen = 2;
+    }
+  } else {
+    if (bdytail == 0.0) {
+      Two_Product(bdxtail, cdy, bt_clarge, bt_c[0]);
+      bt_c[1] = bt_clarge;
+      bt_clen = 2;
+      negate = -bdxtail;
+      Two_Product(negate, ady, bt_alarge, bt_a[0]);
+      bt_a[1] = bt_alarge;
+      bt_alen = 2;
+    } else {
+      Two_Product(bdxtail, cdy, bdxt_cdy1, bdxt_cdy0);
+      Two_Product(bdytail, cdx, bdyt_cdx1, bdyt_cdx0);
+      Two_Two_Diff(bdxt_cdy1, bdxt_cdy0, bdyt_cdx1, bdyt_cdx0,
+                   bt_clarge, bt_c[2], bt_c[1], bt_c[0]);
+      bt_c[3] = bt_clarge;
+      bt_clen = 4;
+      Two_Product(bdytail, adx, bdyt_adx1, bdyt_adx0);
+      Two_Product(bdxtail, ady, bdxt_ady1, bdxt_ady0);
+      Two_Two_Diff(bdyt_adx1, bdyt_adx0, bdxt_ady1, bdxt_ady0,
+                  bt_alarge, bt_a[2], bt_a[1], bt_a[0]);
+      bt_a[3] = bt_alarge;
+      bt_alen = 4;
+    }
+  }
+  if (cdxtail == 0.0) {
+    if (cdytail == 0.0) {
+      ct_a[0] = 0.0;
+      ct_alen = 1;
+      ct_b[0] = 0.0;
+      ct_blen = 1;
+    } else {
+      negate = -cdytail;
+      Two_Product(negate, adx, ct_alarge, ct_a[0]);
+      ct_a[1] = ct_alarge;
+      ct_alen = 2;
+      Two_Product(cdytail, bdx, ct_blarge, ct_b[0]);
+      ct_b[1] = ct_blarge;
+      ct_blen = 2;
+    }
+  } else {
+    if (cdytail == 0.0) {
+      Two_Product(cdxtail, ady, ct_alarge, ct_a[0]);
+      ct_a[1] = ct_alarge;
+      ct_alen = 2;
+      negate = -cdxtail;
+      Two_Product(negate, bdy, ct_blarge, ct_b[0]);
+      ct_b[1] = ct_blarge;
+      ct_blen = 2;
+    } else {
+      Two_Product(cdxtail, ady, cdxt_ady1, cdxt_ady0);
+      Two_Product(cdytail, adx, cdyt_adx1, cdyt_adx0);
+      Two_Two_Diff(cdxt_ady1, cdxt_ady0, cdyt_adx1, cdyt_adx0,
+                   ct_alarge, ct_a[2], ct_a[1], ct_a[0]);
+      ct_a[3] = ct_alarge;
+      ct_alen = 4;
+      Two_Product(cdytail, bdx, cdyt_bdx1, cdyt_bdx0);
+      Two_Product(cdxtail, bdy, cdxt_bdy1, cdxt_bdy0);
+      Two_Two_Diff(cdyt_bdx1, cdyt_bdx0, cdxt_bdy1, cdxt_bdy0,
+                   ct_blarge, ct_b[2], ct_b[1], ct_b[0]);
+      ct_b[3] = ct_blarge;
+      ct_blen = 4;
+    }
+  }
+
+  bctlen = fast_expansion_sum_zeroelim(bt_clen, bt_c, ct_blen, ct_b, bct);
+  wlength = scale_expansion_zeroelim(bctlen, bct, adz, w);
+  finlength = fast_expansion_sum_zeroelim(finlength, finnow, wlength, w,
+                                          finother);
+  finswap = finnow; finnow = finother; finother = finswap;
+
+  catlen = fast_expansion_sum_zeroelim(ct_alen, ct_a, at_clen, at_c, cat);
+  wlength = scale_expansion_zeroelim(catlen, cat, bdz, w);
+  finlength = fast_expansion_sum_zeroelim(finlength, finnow, wlength, w,
+                                          finother);
+  finswap = finnow; finnow = finother; finother = finswap;
+
+  abtlen = fast_expansion_sum_zeroelim(at_blen, at_b, bt_alen, bt_a, abt);
+  wlength = scale_expansion_zeroelim(abtlen, abt, cdz, w);
+  finlength = fast_expansion_sum_zeroelim(finlength, finnow, wlength, w,
+                                          finother);
+  finswap = finnow; finnow = finother; finother = finswap;
+
+  if (adztail != 0.0) {
+    vlength = scale_expansion_zeroelim(4, bc, adztail, v);
+    finlength = fast_expansion_sum_zeroelim(finlength, finnow, vlength, v,
+                                            finother);
+    finswap = finnow; finnow = finother; finother = finswap;
+  }
+  if (bdztail != 0.0) {
+    vlength = scale_expansion_zeroelim(4, ca, bdztail, v);
+    finlength = fast_expansion_sum_zeroelim(finlength, finnow, vlength, v,
+                                            finother);
+    finswap = finnow; finnow = finother; finother = finswap;
+  }
+  if (cdztail != 0.0) {
+    vlength = scale_expansion_zeroelim(4, ab, cdztail, v);
+    finlength = fast_expansion_sum_zeroelim(finlength, finnow, vlength, v,
+                                            finother);
+    finswap = finnow; finnow = finother; finother = finswap;
+  }
+
+  if (adxtail != 0.0) {
+    if (bdytail != 0.0) {
+      Two_Product(adxtail, bdytail, adxt_bdyt1, adxt_bdyt0);
+      Two_One_Product(adxt_bdyt1, adxt_bdyt0, cdz, u3, u[2], u[1], u[0]);
+      u[3] = u3;
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
+                                              finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+      if (cdztail != 0.0) {
+        Two_One_Product(adxt_bdyt1, adxt_bdyt0, cdztail, u3, u[2], u[1], u[0]);
+        u[3] = u3;
+        finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
+                                                finother);
+        finswap = finnow; finnow = finother; finother = finswap;
+      }
+    }
+    if (cdytail != 0.0) {
+      negate = -adxtail;
+      Two_Product(negate, cdytail, adxt_cdyt1, adxt_cdyt0);
+      Two_One_Product(adxt_cdyt1, adxt_cdyt0, bdz, u3, u[2], u[1], u[0]);
+      u[3] = u3;
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
+                                              finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+      if (bdztail != 0.0) {
+        Two_One_Product(adxt_cdyt1, adxt_cdyt0, bdztail, u3, u[2], u[1], u[0]);
+        u[3] = u3;
+        finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
+                                                finother);
+        finswap = finnow; finnow = finother; finother = finswap;
+      }
+    }
+  }
+  if (bdxtail != 0.0) {
+    if (cdytail != 0.0) {
+      Two_Product(bdxtail, cdytail, bdxt_cdyt1, bdxt_cdyt0);
+      Two_One_Product(bdxt_cdyt1, bdxt_cdyt0, adz, u3, u[2], u[1], u[0]);
+      u[3] = u3;
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
+                                              finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+      if (adztail != 0.0) {
+        Two_One_Product(bdxt_cdyt1, bdxt_cdyt0, adztail, u3, u[2], u[1], u[0]);
+        u[3] = u3;
+        finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
+                                                finother);
+        finswap = finnow; finnow = finother; finother = finswap;
+      }
+    }
+    if (adytail != 0.0) {
+      negate = -bdxtail;
+      Two_Product(negate, adytail, bdxt_adyt1, bdxt_adyt0);
+      Two_One_Product(bdxt_adyt1, bdxt_adyt0, cdz, u3, u[2], u[1], u[0]);
+      u[3] = u3;
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
+                                              finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+      if (cdztail != 0.0) {
+        Two_One_Product(bdxt_adyt1, bdxt_adyt0, cdztail, u3, u[2], u[1], u[0]);
+        u[3] = u3;
+        finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
+                                                finother);
+        finswap = finnow; finnow = finother; finother = finswap;
+      }
+    }
+  }
+  if (cdxtail != 0.0) {
+    if (adytail != 0.0) {
+      Two_Product(cdxtail, adytail, cdxt_adyt1, cdxt_adyt0);
+      Two_One_Product(cdxt_adyt1, cdxt_adyt0, bdz, u3, u[2], u[1], u[0]);
+      u[3] = u3;
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
+                                              finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+      if (bdztail != 0.0) {
+        Two_One_Product(cdxt_adyt1, cdxt_adyt0, bdztail, u3, u[2], u[1], u[0]);
+        u[3] = u3;
+        finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
+                                                finother);
+        finswap = finnow; finnow = finother; finother = finswap;
+      }
+    }
+    if (bdytail != 0.0) {
+      negate = -cdxtail;
+      Two_Product(negate, bdytail, cdxt_bdyt1, cdxt_bdyt0);
+      Two_One_Product(cdxt_bdyt1, cdxt_bdyt0, adz, u3, u[2], u[1], u[0]);
+      u[3] = u3;
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
+                                              finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+      if (adztail != 0.0) {
+        Two_One_Product(cdxt_bdyt1, cdxt_bdyt0, adztail, u3, u[2], u[1], u[0]);
+        u[3] = u3;
+        finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
+                                                finother);
+        finswap = finnow; finnow = finother; finother = finswap;
+      }
+    }
+  }
+
+  if (adztail != 0.0) {
+    wlength = scale_expansion_zeroelim(bctlen, bct, adztail, w);
+    finlength = fast_expansion_sum_zeroelim(finlength, finnow, wlength, w,
+                                            finother);
+    finswap = finnow; finnow = finother; finother = finswap;
+  }
+  if (bdztail != 0.0) {
+    wlength = scale_expansion_zeroelim(catlen, cat, bdztail, w);
+    finlength = fast_expansion_sum_zeroelim(finlength, finnow, wlength, w,
+                                            finother);
+    finswap = finnow; finnow = finother; finother = finswap;
+  }
+  if (cdztail != 0.0) {
+    wlength = scale_expansion_zeroelim(abtlen, abt, cdztail, w);
+    finlength = fast_expansion_sum_zeroelim(finlength, finnow, wlength, w,
+                                            finother);
+    finswap = finnow; finnow = finother; finother = finswap;
+  }
+
+  return finnow[finlength - 1];
+}
+
+REAL orient3d(pa, pb, pc, pd)
+REAL *pa;
+REAL *pb;
+REAL *pc;
+REAL *pd;
+{
+  REAL adx, bdx, cdx, ady, bdy, cdy, adz, bdz, cdz;
+  REAL bdxcdy, cdxbdy, cdxady, adxcdy, adxbdy, bdxady;
+  REAL det;
+  REAL permanent, errbound;
+  REAL orient;
+
+  FPU_ROUND_DOUBLE;
+
+  adx = pa[0] - pd[0];
+  bdx = pb[0] - pd[0];
+  cdx = pc[0] - pd[0];
+  ady = pa[1] - pd[1];
+  bdy = pb[1] - pd[1];
+  cdy = pc[1] - pd[1];
+  adz = pa[2] - pd[2];
+  bdz = pb[2] - pd[2];
+  cdz = pc[2] - pd[2];
+
+  bdxcdy = bdx * cdy;
+  cdxbdy = cdx * bdy;
+
+  cdxady = cdx * ady;
+  adxcdy = adx * cdy;
+
+  adxbdy = adx * bdy;
+  bdxady = bdx * ady;
+
+  det = adz * (bdxcdy - cdxbdy) 
+      + bdz * (cdxady - adxcdy)
+      + cdz * (adxbdy - bdxady);
+
+  permanent = (Absolute(bdxcdy) + Absolute(cdxbdy)) * Absolute(adz)
+            + (Absolute(cdxady) + Absolute(adxcdy)) * Absolute(bdz)
+            + (Absolute(adxbdy) + Absolute(bdxady)) * Absolute(cdz);
+  errbound = o3derrboundA * permanent;
+  if ((det > errbound) || (-det > errbound)) {
+    FPU_RESTORE;
+    return det;
+  }
+
+  orient = orient3dadapt(pa, pb, pc, pd, permanent);
+  FPU_RESTORE;
+  return orient;
+}
+
+/*****************************************************************************/
+/*                                                                           */
+/*  incirclefast()   Approximate 2D incircle test.  Nonrobust.               */
+/*  incircleexact()   Exact 2D incircle test.  Robust.                       */
+/*  incircleslow()   Another exact 2D incircle test.  Robust.                */
+/*  incircle()   Adaptive exact 2D incircle test.  Robust.                   */
+/*                                                                           */
+/*               Return a positive value if the point pd lies inside the     */
+/*               circle passing through pa, pb, and pc; a negative value if  */
+/*               it lies outside; and zero if the four points are cocircular.*/
+/*               The points pa, pb, and pc must be in counterclockwise       */
+/*               order, or the sign of the result will be reversed.          */
+/*                                                                           */
+/*  Only the first and last routine should be used; the middle two are for   */
+/*  timings.                                                                 */
+/*                                                                           */
+/*  The last three use exact arithmetic to ensure a correct answer.  The     */
+/*  result returned is the determinant of a matrix.  In incircle() only,     */
+/*  this determinant is computed adaptively, in the sense that exact         */
+/*  arithmetic is used only to the degree it is needed to ensure that the    */
+/*  returned value has the correct sign.  Hence, incircle() is usually quite */
+/*  fast, but will run more slowly when the input points are cocircular or   */
+/*  nearly so.                                                               */
+/*                                                                           */
+/*****************************************************************************/
+
+static REAL incircleadapt(REAL *pa, REAL *pb, REAL *pc, REAL *pd, 
+			  REAL permanent)
+{
+  INEXACT REAL adx, bdx, cdx, ady, bdy, cdy;
+  REAL det, errbound;
+
+  INEXACT REAL bdxcdy1, cdxbdy1, cdxady1, adxcdy1, adxbdy1, bdxady1;
+  REAL bdxcdy0, cdxbdy0, cdxady0, adxcdy0, adxbdy0, bdxady0;
+  REAL bc[4], ca[4], ab[4];
+  INEXACT REAL bc3, ca3, ab3;
+  REAL axbc[8], axxbc[16], aybc[8], ayybc[16], adet[32];
+  int axbclen, axxbclen, aybclen, ayybclen, alen;
+  REAL bxca[8], bxxca[16], byca[8], byyca[16], bdet[32];
+  int bxcalen, bxxcalen, bycalen, byycalen, blen;
+  REAL cxab[8], cxxab[16], cyab[8], cyyab[16], cdet[32];
+  int cxablen, cxxablen, cyablen, cyyablen, clen;
+  REAL abdet[64];
+  int ablen;
+  REAL fin1[1152], fin2[1152];
+  REAL *finnow, *finother, *finswap;
+  int finlength;
+
+  REAL adxtail, bdxtail, cdxtail, adytail, bdytail, cdytail;
+  INEXACT REAL adxadx1, adyady1, bdxbdx1, bdybdy1, cdxcdx1, cdycdy1;
+  REAL adxadx0, adyady0, bdxbdx0, bdybdy0, cdxcdx0, cdycdy0;
+  REAL aa[4], bb[4], cc[4];
+  INEXACT REAL aa3, bb3, cc3;
+  INEXACT REAL ti1, tj1;
+  REAL ti0, tj0;
+  REAL u[4], v[4];
+  INEXACT REAL u3, v3;
+  REAL temp8[8], temp16a[16], temp16b[16], temp16c[16];
+  REAL temp32a[32], temp32b[32], temp48[48], temp64[64];
+  int temp8len, temp16alen, temp16blen, temp16clen;
+  int temp32alen, temp32blen, temp48len, temp64len;
+  REAL axtbb[8], axtcc[8], aytbb[8], aytcc[8];
+  int axtbblen, axtcclen, aytbblen, aytcclen;
+  REAL bxtaa[8], bxtcc[8], bytaa[8], bytcc[8];
+  int bxtaalen, bxtcclen, bytaalen, bytcclen;
+  REAL cxtaa[8], cxtbb[8], cytaa[8], cytbb[8];
+  int cxtaalen, cxtbblen, cytaalen, cytbblen;
+  REAL axtbc[8], aytbc[8], bxtca[8], bytca[8], cxtab[8], cytab[8];
+  int axtbclen = 0, aytbclen = 0;
+  int bxtcalen = 0, bytcalen = 0;
+  int cxtablen = 0, cytablen = 0;
+  REAL axtbct[16], aytbct[16], bxtcat[16], bytcat[16], cxtabt[16], cytabt[16];
+  int axtbctlen, aytbctlen, bxtcatlen, bytcatlen, cxtabtlen, cytabtlen;
+  REAL axtbctt[8], aytbctt[8], bxtcatt[8];
+  REAL bytcatt[8], cxtabtt[8], cytabtt[8];
+  int axtbcttlen, aytbcttlen, bxtcattlen, bytcattlen, cxtabttlen, cytabttlen;
+  REAL abt[8], bct[8], cat[8];
+  int abtlen, bctlen, catlen;
+  REAL abtt[4], bctt[4], catt[4];
+  int abttlen, bcttlen, cattlen;
+  INEXACT REAL abtt3, bctt3, catt3;
+  REAL negate;
+
+  INEXACT REAL bvirt;
+  REAL avirt, bround, around;
+  INEXACT REAL c;
+  INEXACT REAL abig;
+  REAL ahi, alo, bhi, blo;
+  REAL err1, err2, err3;
+  INEXACT REAL _i, _j;
+  REAL _0;
+
+  adx = (REAL) (pa[0] - pd[0]);
+  bdx = (REAL) (pb[0] - pd[0]);
+  cdx = (REAL) (pc[0] - pd[0]);
+  ady = (REAL) (pa[1] - pd[1]);
+  bdy = (REAL) (pb[1] - pd[1]);
+  cdy = (REAL) (pc[1] - pd[1]);
+
+  Two_Product(bdx, cdy, bdxcdy1, bdxcdy0);
+  Two_Product(cdx, bdy, cdxbdy1, cdxbdy0);
+  Two_Two_Diff(bdxcdy1, bdxcdy0, cdxbdy1, cdxbdy0, bc3, bc[2], bc[1], bc[0]);
+  bc[3] = bc3;
+  axbclen = scale_expansion_zeroelim(4, bc, adx, axbc);
+  axxbclen = scale_expansion_zeroelim(axbclen, axbc, adx, axxbc);
+  aybclen = scale_expansion_zeroelim(4, bc, ady, aybc);
+  ayybclen = scale_expansion_zeroelim(aybclen, aybc, ady, ayybc);
+  alen = fast_expansion_sum_zeroelim(axxbclen, axxbc, ayybclen, ayybc, adet);
+
+  Two_Product(cdx, ady, cdxady1, cdxady0);
+  Two_Product(adx, cdy, adxcdy1, adxcdy0);
+  Two_Two_Diff(cdxady1, cdxady0, adxcdy1, adxcdy0, ca3, ca[2], ca[1], ca[0]);
+  ca[3] = ca3;
+  bxcalen = scale_expansion_zeroelim(4, ca, bdx, bxca);
+  bxxcalen = scale_expansion_zeroelim(bxcalen, bxca, bdx, bxxca);
+  bycalen = scale_expansion_zeroelim(4, ca, bdy, byca);
+  byycalen = scale_expansion_zeroelim(bycalen, byca, bdy, byyca);
+  blen = fast_expansion_sum_zeroelim(bxxcalen, bxxca, byycalen, byyca, bdet);
+
+  Two_Product(adx, bdy, adxbdy1, adxbdy0);
+  Two_Product(bdx, ady, bdxady1, bdxady0);
+  Two_Two_Diff(adxbdy1, adxbdy0, bdxady1, bdxady0, ab3, ab[2], ab[1], ab[0]);
+  ab[3] = ab3;
+  cxablen = scale_expansion_zeroelim(4, ab, cdx, cxab);
+  cxxablen = scale_expansion_zeroelim(cxablen, cxab, cdx, cxxab);
+  cyablen = scale_expansion_zeroelim(4, ab, cdy, cyab);
+  cyyablen = scale_expansion_zeroelim(cyablen, cyab, cdy, cyyab);
+  clen = fast_expansion_sum_zeroelim(cxxablen, cxxab, cyyablen, cyyab, cdet);
+
+  ablen = fast_expansion_sum_zeroelim(alen, adet, blen, bdet, abdet);
+  finlength = fast_expansion_sum_zeroelim(ablen, abdet, clen, cdet, fin1);
+
+  det = estimate(finlength, fin1);
+  errbound = iccerrboundB * permanent;
+  if ((det >= errbound) || (-det >= errbound)) {
+    return det;
+  }
+
+  Two_Diff_Tail(pa[0], pd[0], adx, adxtail);
+  Two_Diff_Tail(pa[1], pd[1], ady, adytail);
+  Two_Diff_Tail(pb[0], pd[0], bdx, bdxtail);
+  Two_Diff_Tail(pb[1], pd[1], bdy, bdytail);
+  Two_Diff_Tail(pc[0], pd[0], cdx, cdxtail);
+  Two_Diff_Tail(pc[1], pd[1], cdy, cdytail);
+  if ((adxtail == 0.0) && (bdxtail == 0.0) && (cdxtail == 0.0)
+      && (adytail == 0.0) && (bdytail == 0.0) && (cdytail == 0.0)) {
+    return det;
+  }
+
+  errbound = iccerrboundC * permanent + resulterrbound * Absolute(det);
+  det += ((adx * adx + ady * ady) * ((bdx * cdytail + cdy * bdxtail)
+                                     - (bdy * cdxtail + cdx * bdytail))
+          + 2.0 * (adx * adxtail + ady * adytail) * (bdx * cdy - bdy * cdx))
+       + ((bdx * bdx + bdy * bdy) * ((cdx * adytail + ady * cdxtail)
+                                     - (cdy * adxtail + adx * cdytail))
+          + 2.0 * (bdx * bdxtail + bdy * bdytail) * (cdx * ady - cdy * adx))
+       + ((cdx * cdx + cdy * cdy) * ((adx * bdytail + bdy * adxtail)
+                                     - (ady * bdxtail + bdx * adytail))
+          + 2.0 * (cdx * cdxtail + cdy * cdytail) * (adx * bdy - ady * bdx));
+  if ((det >= errbound) || (-det >= errbound)) {
+    return det;
+  }
+
+  finnow = fin1;
+  finother = fin2;
+
+  if ((bdxtail != 0.0) || (bdytail != 0.0)
+      || (cdxtail != 0.0) || (cdytail != 0.0)) {
+    Square(adx, adxadx1, adxadx0);
+    Square(ady, adyady1, adyady0);
+    Two_Two_Sum(adxadx1, adxadx0, adyady1, adyady0, aa3, aa[2], aa[1], aa[0]);
+    aa[3] = aa3;
+  }
+  if ((cdxtail != 0.0) || (cdytail != 0.0)
+      || (adxtail != 0.0) || (adytail != 0.0)) {
+    Square(bdx, bdxbdx1, bdxbdx0);
+    Square(bdy, bdybdy1, bdybdy0);
+    Two_Two_Sum(bdxbdx1, bdxbdx0, bdybdy1, bdybdy0, bb3, bb[2], bb[1], bb[0]);
+    bb[3] = bb3;
+  }
+  if ((adxtail != 0.0) || (adytail != 0.0)
+      || (bdxtail != 0.0) || (bdytail != 0.0)) {
+    Square(cdx, cdxcdx1, cdxcdx0);
+    Square(cdy, cdycdy1, cdycdy0);
+    Two_Two_Sum(cdxcdx1, cdxcdx0, cdycdy1, cdycdy0, cc3, cc[2], cc[1], cc[0]);
+    cc[3] = cc3;
+  }
+
+  if (adxtail != 0.0) {
+    axtbclen = scale_expansion_zeroelim(4, bc, adxtail, axtbc);
+    temp16alen = scale_expansion_zeroelim(axtbclen, axtbc, 2.0 * adx,
+                                          temp16a);
+
+    axtcclen = scale_expansion_zeroelim(4, cc, adxtail, axtcc);
+    temp16blen = scale_expansion_zeroelim(axtcclen, axtcc, bdy, temp16b);
+
+    axtbblen = scale_expansion_zeroelim(4, bb, adxtail, axtbb);
+    temp16clen = scale_expansion_zeroelim(axtbblen, axtbb, -cdy, temp16c);
+
+    temp32alen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                            temp16blen, temp16b, temp32a);
+    temp48len = fast_expansion_sum_zeroelim(temp16clen, temp16c,
+                                            temp32alen, temp32a, temp48);
+    finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
+                                            temp48, finother);
+    finswap = finnow; finnow = finother; finother = finswap;
+  }
+  if (adytail != 0.0) {
+    aytbclen = scale_expansion_zeroelim(4, bc, adytail, aytbc);
+    temp16alen = scale_expansion_zeroelim(aytbclen, aytbc, 2.0 * ady,
+                                          temp16a);
+
+    aytbblen = scale_expansion_zeroelim(4, bb, adytail, aytbb);
+    temp16blen = scale_expansion_zeroelim(aytbblen, aytbb, cdx, temp16b);
+
+    aytcclen = scale_expansion_zeroelim(4, cc, adytail, aytcc);
+    temp16clen = scale_expansion_zeroelim(aytcclen, aytcc, -bdx, temp16c);
+
+    temp32alen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                            temp16blen, temp16b, temp32a);
+    temp48len = fast_expansion_sum_zeroelim(temp16clen, temp16c,
+                                            temp32alen, temp32a, temp48);
+    finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
+                                            temp48, finother);
+    finswap = finnow; finnow = finother; finother = finswap;
+  }
+  if (bdxtail != 0.0) {
+    bxtcalen = scale_expansion_zeroelim(4, ca, bdxtail, bxtca);
+    temp16alen = scale_expansion_zeroelim(bxtcalen, bxtca, 2.0 * bdx,
+                                          temp16a);
+
+    bxtaalen = scale_expansion_zeroelim(4, aa, bdxtail, bxtaa);
+    temp16blen = scale_expansion_zeroelim(bxtaalen, bxtaa, cdy, temp16b);
+
+    bxtcclen = scale_expansion_zeroelim(4, cc, bdxtail, bxtcc);
+    temp16clen = scale_expansion_zeroelim(bxtcclen, bxtcc, -ady, temp16c);
+
+    temp32alen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                            temp16blen, temp16b, temp32a);
+    temp48len = fast_expansion_sum_zeroelim(temp16clen, temp16c,
+                                            temp32alen, temp32a, temp48);
+    finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
+                                            temp48, finother);
+    finswap = finnow; finnow = finother; finother = finswap;
+  }
+  if (bdytail != 0.0) {
+    bytcalen = scale_expansion_zeroelim(4, ca, bdytail, bytca);
+    temp16alen = scale_expansion_zeroelim(bytcalen, bytca, 2.0 * bdy,
+                                          temp16a);
+
+    bytcclen = scale_expansion_zeroelim(4, cc, bdytail, bytcc);
+    temp16blen = scale_expansion_zeroelim(bytcclen, bytcc, adx, temp16b);
+
+    bytaalen = scale_expansion_zeroelim(4, aa, bdytail, bytaa);
+    temp16clen = scale_expansion_zeroelim(bytaalen, bytaa, -cdx, temp16c);
+
+    temp32alen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                            temp16blen, temp16b, temp32a);
+    temp48len = fast_expansion_sum_zeroelim(temp16clen, temp16c,
+                                            temp32alen, temp32a, temp48);
+    finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
+                                            temp48, finother);
+    finswap = finnow; finnow = finother; finother = finswap;
+  }
+  if (cdxtail != 0.0) {
+    cxtablen = scale_expansion_zeroelim(4, ab, cdxtail, cxtab);
+    temp16alen = scale_expansion_zeroelim(cxtablen, cxtab, 2.0 * cdx,
+                                          temp16a);
+
+    cxtbblen = scale_expansion_zeroelim(4, bb, cdxtail, cxtbb);
+    temp16blen = scale_expansion_zeroelim(cxtbblen, cxtbb, ady, temp16b);
+
+    cxtaalen = scale_expansion_zeroelim(4, aa, cdxtail, cxtaa);
+    temp16clen = scale_expansion_zeroelim(cxtaalen, cxtaa, -bdy, temp16c);
+
+    temp32alen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                            temp16blen, temp16b, temp32a);
+    temp48len = fast_expansion_sum_zeroelim(temp16clen, temp16c,
+                                            temp32alen, temp32a, temp48);
+    finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
+                                            temp48, finother);
+    finswap = finnow; finnow = finother; finother = finswap;
+  }
+  if (cdytail != 0.0) {
+    cytablen = scale_expansion_zeroelim(4, ab, cdytail, cytab);
+    temp16alen = scale_expansion_zeroelim(cytablen, cytab, 2.0 * cdy,
+                                          temp16a);
+
+    cytaalen = scale_expansion_zeroelim(4, aa, cdytail, cytaa);
+    temp16blen = scale_expansion_zeroelim(cytaalen, cytaa, bdx, temp16b);
+
+    cytbblen = scale_expansion_zeroelim(4, bb, cdytail, cytbb);
+    temp16clen = scale_expansion_zeroelim(cytbblen, cytbb, -adx, temp16c);
+
+    temp32alen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                            temp16blen, temp16b, temp32a);
+    temp48len = fast_expansion_sum_zeroelim(temp16clen, temp16c,
+                                            temp32alen, temp32a, temp48);
+    finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
+                                            temp48, finother);
+    finswap = finnow; finnow = finother; finother = finswap;
+  }
+
+  if ((adxtail != 0.0) || (adytail != 0.0)) {
+    if ((bdxtail != 0.0) || (bdytail != 0.0)
+        || (cdxtail != 0.0) || (cdytail != 0.0)) {
+      Two_Product(bdxtail, cdy, ti1, ti0);
+      Two_Product(bdx, cdytail, tj1, tj0);
+      Two_Two_Sum(ti1, ti0, tj1, tj0, u3, u[2], u[1], u[0]);
+      u[3] = u3;
+      negate = -bdy;
+      Two_Product(cdxtail, negate, ti1, ti0);
+      negate = -bdytail;
+      Two_Product(cdx, negate, tj1, tj0);
+      Two_Two_Sum(ti1, ti0, tj1, tj0, v3, v[2], v[1], v[0]);
+      v[3] = v3;
+      bctlen = fast_expansion_sum_zeroelim(4, u, 4, v, bct);
+
+      Two_Product(bdxtail, cdytail, ti1, ti0);
+      Two_Product(cdxtail, bdytail, tj1, tj0);
+      Two_Two_Diff(ti1, ti0, tj1, tj0, bctt3, bctt[2], bctt[1], bctt[0]);
+      bctt[3] = bctt3;
+      bcttlen = 4;
+    } else {
+      bct[0] = 0.0;
+      bctlen = 1;
+      bctt[0] = 0.0;
+      bcttlen = 1;
+    }
+
+    if (adxtail != 0.0) {
+      temp16alen = scale_expansion_zeroelim(axtbclen, axtbc, adxtail, temp16a);
+      axtbctlen = scale_expansion_zeroelim(bctlen, bct, adxtail, axtbct);
+      temp32alen = scale_expansion_zeroelim(axtbctlen, axtbct, 2.0 * adx,
+                                            temp32a);
+      temp48len = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                              temp32alen, temp32a, temp48);
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
+                                              temp48, finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+      if (bdytail != 0.0) {
+        temp8len = scale_expansion_zeroelim(4, cc, adxtail, temp8);
+        temp16alen = scale_expansion_zeroelim(temp8len, temp8, bdytail,
+                                              temp16a);
+        finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp16alen,
+                                                temp16a, finother);
+        finswap = finnow; finnow = finother; finother = finswap;
+      }
+      if (cdytail != 0.0) {
+        temp8len = scale_expansion_zeroelim(4, bb, -adxtail, temp8);
+        temp16alen = scale_expansion_zeroelim(temp8len, temp8, cdytail,
+                                              temp16a);
+        finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp16alen,
+                                                temp16a, finother);
+        finswap = finnow; finnow = finother; finother = finswap;
+      }
+
+      temp32alen = scale_expansion_zeroelim(axtbctlen, axtbct, adxtail,
+                                            temp32a);
+      axtbcttlen = scale_expansion_zeroelim(bcttlen, bctt, adxtail, axtbctt);
+      temp16alen = scale_expansion_zeroelim(axtbcttlen, axtbctt, 2.0 * adx,
+                                            temp16a);
+      temp16blen = scale_expansion_zeroelim(axtbcttlen, axtbctt, adxtail,
+                                            temp16b);
+      temp32blen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                              temp16blen, temp16b, temp32b);
+      temp64len = fast_expansion_sum_zeroelim(temp32alen, temp32a,
+                                              temp32blen, temp32b, temp64);
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp64len,
+                                              temp64, finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+    }
+    if (adytail != 0.0) {
+      temp16alen = scale_expansion_zeroelim(aytbclen, aytbc, adytail, temp16a);
+      aytbctlen = scale_expansion_zeroelim(bctlen, bct, adytail, aytbct);
+      temp32alen = scale_expansion_zeroelim(aytbctlen, aytbct, 2.0 * ady,
+                                            temp32a);
+      temp48len = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                              temp32alen, temp32a, temp48);
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
+                                              temp48, finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+
+
+      temp32alen = scale_expansion_zeroelim(aytbctlen, aytbct, adytail,
+                                            temp32a);
+      aytbcttlen = scale_expansion_zeroelim(bcttlen, bctt, adytail, aytbctt);
+      temp16alen = scale_expansion_zeroelim(aytbcttlen, aytbctt, 2.0 * ady,
+                                            temp16a);
+      temp16blen = scale_expansion_zeroelim(aytbcttlen, aytbctt, adytail,
+                                            temp16b);
+      temp32blen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                              temp16blen, temp16b, temp32b);
+      temp64len = fast_expansion_sum_zeroelim(temp32alen, temp32a,
+                                              temp32blen, temp32b, temp64);
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp64len,
+                                              temp64, finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+    }
+  }
+  if ((bdxtail != 0.0) || (bdytail != 0.0)) {
+    if ((cdxtail != 0.0) || (cdytail != 0.0)
+        || (adxtail != 0.0) || (adytail != 0.0)) {
+      Two_Product(cdxtail, ady, ti1, ti0);
+      Two_Product(cdx, adytail, tj1, tj0);
+      Two_Two_Sum(ti1, ti0, tj1, tj0, u3, u[2], u[1], u[0]);
+      u[3] = u3;
+      negate = -cdy;
+      Two_Product(adxtail, negate, ti1, ti0);
+      negate = -cdytail;
+      Two_Product(adx, negate, tj1, tj0);
+      Two_Two_Sum(ti1, ti0, tj1, tj0, v3, v[2], v[1], v[0]);
+      v[3] = v3;
+      catlen = fast_expansion_sum_zeroelim(4, u, 4, v, cat);
+
+      Two_Product(cdxtail, adytail, ti1, ti0);
+      Two_Product(adxtail, cdytail, tj1, tj0);
+      Two_Two_Diff(ti1, ti0, tj1, tj0, catt3, catt[2], catt[1], catt[0]);
+      catt[3] = catt3;
+      cattlen = 4;
+    } else {
+      cat[0] = 0.0;
+      catlen = 1;
+      catt[0] = 0.0;
+      cattlen = 1;
+    }
+
+    if (bdxtail != 0.0) {
+      temp16alen = scale_expansion_zeroelim(bxtcalen, bxtca, bdxtail, temp16a);
+      bxtcatlen = scale_expansion_zeroelim(catlen, cat, bdxtail, bxtcat);
+      temp32alen = scale_expansion_zeroelim(bxtcatlen, bxtcat, 2.0 * bdx,
+                                            temp32a);
+      temp48len = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                              temp32alen, temp32a, temp48);
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
+                                              temp48, finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+      if (cdytail != 0.0) {
+        temp8len = scale_expansion_zeroelim(4, aa, bdxtail, temp8);
+        temp16alen = scale_expansion_zeroelim(temp8len, temp8, cdytail,
+                                              temp16a);
+        finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp16alen,
+                                                temp16a, finother);
+        finswap = finnow; finnow = finother; finother = finswap;
+      }
+      if (adytail != 0.0) {
+        temp8len = scale_expansion_zeroelim(4, cc, -bdxtail, temp8);
+        temp16alen = scale_expansion_zeroelim(temp8len, temp8, adytail,
+                                              temp16a);
+        finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp16alen,
+                                                temp16a, finother);
+        finswap = finnow; finnow = finother; finother = finswap;
+      }
+
+      temp32alen = scale_expansion_zeroelim(bxtcatlen, bxtcat, bdxtail,
+                                            temp32a);
+      bxtcattlen = scale_expansion_zeroelim(cattlen, catt, bdxtail, bxtcatt);
+      temp16alen = scale_expansion_zeroelim(bxtcattlen, bxtcatt, 2.0 * bdx,
+                                            temp16a);
+      temp16blen = scale_expansion_zeroelim(bxtcattlen, bxtcatt, bdxtail,
+                                            temp16b);
+      temp32blen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                              temp16blen, temp16b, temp32b);
+      temp64len = fast_expansion_sum_zeroelim(temp32alen, temp32a,
+                                              temp32blen, temp32b, temp64);
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp64len,
+                                              temp64, finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+    }
+    if (bdytail != 0.0) {
+      temp16alen = scale_expansion_zeroelim(bytcalen, bytca, bdytail, temp16a);
+      bytcatlen = scale_expansion_zeroelim(catlen, cat, bdytail, bytcat);
+      temp32alen = scale_expansion_zeroelim(bytcatlen, bytcat, 2.0 * bdy,
+                                            temp32a);
+      temp48len = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                              temp32alen, temp32a, temp48);
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
+                                              temp48, finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+
+
+      temp32alen = scale_expansion_zeroelim(bytcatlen, bytcat, bdytail,
+                                            temp32a);
+      bytcattlen = scale_expansion_zeroelim(cattlen, catt, bdytail, bytcatt);
+      temp16alen = scale_expansion_zeroelim(bytcattlen, bytcatt, 2.0 * bdy,
+                                            temp16a);
+      temp16blen = scale_expansion_zeroelim(bytcattlen, bytcatt, bdytail,
+                                            temp16b);
+      temp32blen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                              temp16blen, temp16b, temp32b);
+      temp64len = fast_expansion_sum_zeroelim(temp32alen, temp32a,
+                                              temp32blen, temp32b, temp64);
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp64len,
+                                              temp64, finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+    }
+  }
+  if ((cdxtail != 0.0) || (cdytail != 0.0)) {
+    if ((adxtail != 0.0) || (adytail != 0.0)
+        || (bdxtail != 0.0) || (bdytail != 0.0)) {
+      Two_Product(adxtail, bdy, ti1, ti0);
+      Two_Product(adx, bdytail, tj1, tj0);
+      Two_Two_Sum(ti1, ti0, tj1, tj0, u3, u[2], u[1], u[0]);
+      u[3] = u3;
+      negate = -ady;
+      Two_Product(bdxtail, negate, ti1, ti0);
+      negate = -adytail;
+      Two_Product(bdx, negate, tj1, tj0);
+      Two_Two_Sum(ti1, ti0, tj1, tj0, v3, v[2], v[1], v[0]);
+      v[3] = v3;
+      abtlen = fast_expansion_sum_zeroelim(4, u, 4, v, abt);
+
+      Two_Product(adxtail, bdytail, ti1, ti0);
+      Two_Product(bdxtail, adytail, tj1, tj0);
+      Two_Two_Diff(ti1, ti0, tj1, tj0, abtt3, abtt[2], abtt[1], abtt[0]);
+      abtt[3] = abtt3;
+      abttlen = 4;
+    } else {
+      abt[0] = 0.0;
+      abtlen = 1;
+      abtt[0] = 0.0;
+      abttlen = 1;
+    }
+
+    if (cdxtail != 0.0) {
+      temp16alen = scale_expansion_zeroelim(cxtablen, cxtab, cdxtail, temp16a);
+      cxtabtlen = scale_expansion_zeroelim(abtlen, abt, cdxtail, cxtabt);
+      temp32alen = scale_expansion_zeroelim(cxtabtlen, cxtabt, 2.0 * cdx,
+                                            temp32a);
+      temp48len = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                              temp32alen, temp32a, temp48);
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
+                                              temp48, finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+      if (adytail != 0.0) {
+        temp8len = scale_expansion_zeroelim(4, bb, cdxtail, temp8);
+        temp16alen = scale_expansion_zeroelim(temp8len, temp8, adytail,
+                                              temp16a);
+        finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp16alen,
+                                                temp16a, finother);
+        finswap = finnow; finnow = finother; finother = finswap;
+      }
+      if (bdytail != 0.0) {
+        temp8len = scale_expansion_zeroelim(4, aa, -cdxtail, temp8);
+        temp16alen = scale_expansion_zeroelim(temp8len, temp8, bdytail,
+                                              temp16a);
+        finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp16alen,
+                                                temp16a, finother);
+        finswap = finnow; finnow = finother; finother = finswap;
+      }
+
+      temp32alen = scale_expansion_zeroelim(cxtabtlen, cxtabt, cdxtail,
+                                            temp32a);
+      cxtabttlen = scale_expansion_zeroelim(abttlen, abtt, cdxtail, cxtabtt);
+      temp16alen = scale_expansion_zeroelim(cxtabttlen, cxtabtt, 2.0 * cdx,
+                                            temp16a);
+      temp16blen = scale_expansion_zeroelim(cxtabttlen, cxtabtt, cdxtail,
+                                            temp16b);
+      temp32blen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                              temp16blen, temp16b, temp32b);
+      temp64len = fast_expansion_sum_zeroelim(temp32alen, temp32a,
+                                              temp32blen, temp32b, temp64);
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp64len,
+                                              temp64, finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+    }
+    if (cdytail != 0.0) {
+      temp16alen = scale_expansion_zeroelim(cytablen, cytab, cdytail, temp16a);
+      cytabtlen = scale_expansion_zeroelim(abtlen, abt, cdytail, cytabt);
+      temp32alen = scale_expansion_zeroelim(cytabtlen, cytabt, 2.0 * cdy,
+                                            temp32a);
+      temp48len = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                              temp32alen, temp32a, temp48);
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
+                                              temp48, finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+
+
+      temp32alen = scale_expansion_zeroelim(cytabtlen, cytabt, cdytail,
+                                            temp32a);
+      cytabttlen = scale_expansion_zeroelim(abttlen, abtt, cdytail, cytabtt);
+      temp16alen = scale_expansion_zeroelim(cytabttlen, cytabtt, 2.0 * cdy,
+                                            temp16a);
+      temp16blen = scale_expansion_zeroelim(cytabttlen, cytabtt, cdytail,
+                                            temp16b);
+      temp32blen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
+                                              temp16blen, temp16b, temp32b);
+      temp64len = fast_expansion_sum_zeroelim(temp32alen, temp32a,
+                                              temp32blen, temp32b, temp64);
+      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp64len,
+                                              temp64, finother);
+      finswap = finnow; finnow = finother; finother = finswap;
+    }
+  }
+
+  return finnow[finlength - 1];
+}
+
+REAL incircle(pa, pb, pc, pd)
+REAL *pa;
+REAL *pb;
+REAL *pc;
+REAL *pd;
+{
+  REAL adx, bdx, cdx, ady, bdy, cdy;
+  REAL bdxcdy, cdxbdy, cdxady, adxcdy, adxbdy, bdxady;
+  REAL alift, blift, clift;
+  REAL det;
+  REAL permanent, errbound;
+  REAL inc;
+
+  FPU_ROUND_DOUBLE;
+  
+  adx = pa[0] - pd[0];
+  bdx = pb[0] - pd[0];
+  cdx = pc[0] - pd[0];
+  ady = pa[1] - pd[1];
+  bdy = pb[1] - pd[1];
+  cdy = pc[1] - pd[1];
+
+  bdxcdy = bdx * cdy;
+  cdxbdy = cdx * bdy;
+  alift = adx * adx + ady * ady;
+
+  cdxady = cdx * ady;
+  adxcdy = adx * cdy;
+  blift = bdx * bdx + bdy * bdy;
+
+  adxbdy = adx * bdy;
+  bdxady = bdx * ady;
+  clift = cdx * cdx + cdy * cdy;
+
+  det = alift * (bdxcdy - cdxbdy)
+      + blift * (cdxady - adxcdy)
+      + clift * (adxbdy - bdxady);
+
+  permanent = (Absolute(bdxcdy) + Absolute(cdxbdy)) * alift
+            + (Absolute(cdxady) + Absolute(adxcdy)) * blift
+            + (Absolute(adxbdy) + Absolute(bdxady)) * clift;
+  errbound = iccerrboundA * permanent;
+  if ((det > errbound) || (-det > errbound)) {
+    FPU_RESTORE;
+    return det;
+  }
+
+  inc = incircleadapt(pa, pb, pc, pd, permanent);
+  FPU_RESTORE;
+  return inc;
+}
+
+/*****************************************************************************/
+/*                                                                           */
+/*  inspherefast()   Approximate 3D insphere test.  Nonrobust.               */
+/*  insphereexact()   Exact 3D insphere test.  Robust.                       */
+/*  insphereslow()   Another exact 3D insphere test.  Robust.                */
+/*  insphere()   Adaptive exact 3D insphere test.  Robust.                   */
+/*                                                                           */
+/*               Return a positive value if the point pe lies inside the     */
+/*               sphere passing through pa, pb, pc, and pd; a negative value */
+/*               if it lies outside; and zero if the five points are         */
+/*               cospherical.  The points pa, pb, pc, and pd must be ordered */
+/*               so that they have a positive orientation (as defined by     */
+/*               orient3d()), or the sign of the result will be reversed.    */
+/*                                                                           */
+/*  Only the first and last routine should be used; the middle two are for   */
+/*  timings.                                                                 */
+/*                                                                           */
+/*  The last three use exact arithmetic to ensure a correct answer.  The     */
+/*  result returned is the determinant of a matrix.  In insphere() only,     */
+/*  this determinant is computed adaptively, in the sense that exact         */
+/*  arithmetic is used only to the degree it is needed to ensure that the    */
+/*  returned value has the correct sign.  Hence, insphere() is usually quite */
+/*  fast, but will run more slowly when the input points are cospherical or  */
+/*  nearly so.                                                               */
+/*                                                                           */
+/*****************************************************************************/
+
+static REAL insphereexact(REAL *pa, REAL *pb, REAL *pc, REAL *pd, REAL *pe)
+{
+  INEXACT REAL axby1, bxcy1, cxdy1, dxey1, exay1;
+  INEXACT REAL bxay1, cxby1, dxcy1, exdy1, axey1;
+  INEXACT REAL axcy1, bxdy1, cxey1, dxay1, exby1;
+  INEXACT REAL cxay1, dxby1, excy1, axdy1, bxey1;
+  REAL axby0, bxcy0, cxdy0, dxey0, exay0;
+  REAL bxay0, cxby0, dxcy0, exdy0, axey0;
+  REAL axcy0, bxdy0, cxey0, dxay0, exby0;
+  REAL cxay0, dxby0, excy0, axdy0, bxey0;
+  REAL ab[4], bc[4], cd[4], de[4], ea[4];
+  REAL ac[4], bd[4], ce[4], da[4], eb[4];
+  REAL temp8a[8], temp8b[8], temp16[16];
+  int temp8alen, temp8blen, temp16len;
+  REAL abc[24], bcd[24], cde[24], dea[24], eab[24];
+  REAL abd[24], bce[24], cda[24], deb[24], eac[24];
+  int abclen, bcdlen, cdelen, dealen, eablen;
+  int abdlen, bcelen, cdalen, deblen, eaclen;
+  REAL temp48a[48], temp48b[48];
+  int temp48alen, temp48blen;
+  REAL abcd[96], bcde[96], cdea[96], deab[96], eabc[96];
+  int abcdlen, bcdelen, cdealen, deablen, eabclen;
+  REAL temp192[192];
+  REAL det384x[384], det384y[384], det384z[384];
+  int xlen, ylen, zlen;
+  REAL detxy[768];
+  int xylen;
+  REAL adet[1152], bdet[1152], cdet[1152], ddet[1152], edet[1152];
+  int alen, blen, clen, dlen, elen;
+  REAL abdet[2304], cddet[2304], cdedet[3456];
+  int ablen, cdlen;
+  REAL deter[5760];
+  int deterlen;
+  int i;
+
+  INEXACT REAL bvirt;
+  REAL avirt, bround, around;
+  INEXACT REAL c;
+  INEXACT REAL abig;
+  REAL ahi, alo, bhi, blo;
+  REAL err1, err2, err3;
+  INEXACT REAL _i, _j;
+  REAL _0;
+
+  Two_Product(pa[0], pb[1], axby1, axby0);
+  Two_Product(pb[0], pa[1], bxay1, bxay0);
+  Two_Two_Diff(axby1, axby0, bxay1, bxay0, ab[3], ab[2], ab[1], ab[0]);
+
+  Two_Product(pb[0], pc[1], bxcy1, bxcy0);
+  Two_Product(pc[0], pb[1], cxby1, cxby0);
+  Two_Two_Diff(bxcy1, bxcy0, cxby1, cxby0, bc[3], bc[2], bc[1], bc[0]);
+
+  Two_Product(pc[0], pd[1], cxdy1, cxdy0);
+  Two_Product(pd[0], pc[1], dxcy1, dxcy0);
+  Two_Two_Diff(cxdy1, cxdy0, dxcy1, dxcy0, cd[3], cd[2], cd[1], cd[0]);
+
+  Two_Product(pd[0], pe[1], dxey1, dxey0);
+  Two_Product(pe[0], pd[1], exdy1, exdy0);
+  Two_Two_Diff(dxey1, dxey0, exdy1, exdy0, de[3], de[2], de[1], de[0]);
+
+  Two_Product(pe[0], pa[1], exay1, exay0);
+  Two_Product(pa[0], pe[1], axey1, axey0);
+  Two_Two_Diff(exay1, exay0, axey1, axey0, ea[3], ea[2], ea[1], ea[0]);
+
+  Two_Product(pa[0], pc[1], axcy1, axcy0);
+  Two_Product(pc[0], pa[1], cxay1, cxay0);
+  Two_Two_Diff(axcy1, axcy0, cxay1, cxay0, ac[3], ac[2], ac[1], ac[0]);
+
+  Two_Product(pb[0], pd[1], bxdy1, bxdy0);
+  Two_Product(pd[0], pb[1], dxby1, dxby0);
+  Two_Two_Diff(bxdy1, bxdy0, dxby1, dxby0, bd[3], bd[2], bd[1], bd[0]);
+
+  Two_Product(pc[0], pe[1], cxey1, cxey0);
+  Two_Product(pe[0], pc[1], excy1, excy0);
+  Two_Two_Diff(cxey1, cxey0, excy1, excy0, ce[3], ce[2], ce[1], ce[0]);
+
+  Two_Product(pd[0], pa[1], dxay1, dxay0);
+  Two_Product(pa[0], pd[1], axdy1, axdy0);
+  Two_Two_Diff(dxay1, dxay0, axdy1, axdy0, da[3], da[2], da[1], da[0]);
+
+  Two_Product(pe[0], pb[1], exby1, exby0);
+  Two_Product(pb[0], pe[1], bxey1, bxey0);
+  Two_Two_Diff(exby1, exby0, bxey1, bxey0, eb[3], eb[2], eb[1], eb[0]);
+
+  temp8alen = scale_expansion_zeroelim(4, bc, pa[2], temp8a);
+  temp8blen = scale_expansion_zeroelim(4, ac, -pb[2], temp8b);
+  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
+                                          temp16);
+  temp8alen = scale_expansion_zeroelim(4, ab, pc[2], temp8a);
+  abclen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
+                                       abc);
+
+  temp8alen = scale_expansion_zeroelim(4, cd, pb[2], temp8a);
+  temp8blen = scale_expansion_zeroelim(4, bd, -pc[2], temp8b);
+  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
+                                          temp16);
+  temp8alen = scale_expansion_zeroelim(4, bc, pd[2], temp8a);
+  bcdlen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
+                                       bcd);
+
+  temp8alen = scale_expansion_zeroelim(4, de, pc[2], temp8a);
+  temp8blen = scale_expansion_zeroelim(4, ce, -pd[2], temp8b);
+  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
+                                          temp16);
+  temp8alen = scale_expansion_zeroelim(4, cd, pe[2], temp8a);
+  cdelen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
+                                       cde);
+
+  temp8alen = scale_expansion_zeroelim(4, ea, pd[2], temp8a);
+  temp8blen = scale_expansion_zeroelim(4, da, -pe[2], temp8b);
+  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
+                                          temp16);
+  temp8alen = scale_expansion_zeroelim(4, de, pa[2], temp8a);
+  dealen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
+                                       dea);
+
+  temp8alen = scale_expansion_zeroelim(4, ab, pe[2], temp8a);
+  temp8blen = scale_expansion_zeroelim(4, eb, -pa[2], temp8b);
+  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
+                                          temp16);
+  temp8alen = scale_expansion_zeroelim(4, ea, pb[2], temp8a);
+  eablen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
+                                       eab);
+
+  temp8alen = scale_expansion_zeroelim(4, bd, pa[2], temp8a);
+  temp8blen = scale_expansion_zeroelim(4, da, pb[2], temp8b);
+  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
+                                          temp16);
+  temp8alen = scale_expansion_zeroelim(4, ab, pd[2], temp8a);
+  abdlen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
+                                       abd);
+
+  temp8alen = scale_expansion_zeroelim(4, ce, pb[2], temp8a);
+  temp8blen = scale_expansion_zeroelim(4, eb, pc[2], temp8b);
+  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
+                                          temp16);
+  temp8alen = scale_expansion_zeroelim(4, bc, pe[2], temp8a);
+  bcelen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
+                                       bce);
+
+  temp8alen = scale_expansion_zeroelim(4, da, pc[2], temp8a);
+  temp8blen = scale_expansion_zeroelim(4, ac, pd[2], temp8b);
+  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
+                                          temp16);
+  temp8alen = scale_expansion_zeroelim(4, cd, pa[2], temp8a);
+  cdalen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
+                                       cda);
+
+  temp8alen = scale_expansion_zeroelim(4, eb, pd[2], temp8a);
+  temp8blen = scale_expansion_zeroelim(4, bd, pe[2], temp8b);
+  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
+                                          temp16);
+  temp8alen = scale_expansion_zeroelim(4, de, pb[2], temp8a);
+  deblen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
+                                       deb);
+
+  temp8alen = scale_expansion_zeroelim(4, ac, pe[2], temp8a);
+  temp8blen = scale_expansion_zeroelim(4, ce, pa[2], temp8b);
+  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
+                                          temp16);
+  temp8alen = scale_expansion_zeroelim(4, ea, pc[2], temp8a);
+  eaclen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
+                                       eac);
+
+  temp48alen = fast_expansion_sum_zeroelim(cdelen, cde, bcelen, bce, temp48a);
+  temp48blen = fast_expansion_sum_zeroelim(deblen, deb, bcdlen, bcd, temp48b);
+  for (i = 0; i < temp48blen; i++) {
+    temp48b[i] = -temp48b[i];
+  }
+  bcdelen = fast_expansion_sum_zeroelim(temp48alen, temp48a,
+                                        temp48blen, temp48b, bcde);
+  xlen = scale_expansion_zeroelim(bcdelen, bcde, pa[0], temp192);
+  xlen = scale_expansion_zeroelim(xlen, temp192, pa[0], det384x);
+  ylen = scale_expansion_zeroelim(bcdelen, bcde, pa[1], temp192);
+  ylen = scale_expansion_zeroelim(ylen, temp192, pa[1], det384y);
+  zlen = scale_expansion_zeroelim(bcdelen, bcde, pa[2], temp192);
+  zlen = scale_expansion_zeroelim(zlen, temp192, pa[2], det384z);
+  xylen = fast_expansion_sum_zeroelim(xlen, det384x, ylen, det384y, detxy);
+  alen = fast_expansion_sum_zeroelim(xylen, detxy, zlen, det384z, adet);
+
+  temp48alen = fast_expansion_sum_zeroelim(dealen, dea, cdalen, cda, temp48a);
+  temp48blen = fast_expansion_sum_zeroelim(eaclen, eac, cdelen, cde, temp48b);
+  for (i = 0; i < temp48blen; i++) {
+    temp48b[i] = -temp48b[i];
+  }
+  cdealen = fast_expansion_sum_zeroelim(temp48alen, temp48a,
+                                        temp48blen, temp48b, cdea);
+  xlen = scale_expansion_zeroelim(cdealen, cdea, pb[0], temp192);
+  xlen = scale_expansion_zeroelim(xlen, temp192, pb[0], det384x);
+  ylen = scale_expansion_zeroelim(cdealen, cdea, pb[1], temp192);
+  ylen = scale_expansion_zeroelim(ylen, temp192, pb[1], det384y);
+  zlen = scale_expansion_zeroelim(cdealen, cdea, pb[2], temp192);
+  zlen = scale_expansion_zeroelim(zlen, temp192, pb[2], det384z);
+  xylen = fast_expansion_sum_zeroelim(xlen, det384x, ylen, det384y, detxy);
+  blen = fast_expansion_sum_zeroelim(xylen, detxy, zlen, det384z, bdet);
+
+  temp48alen = fast_expansion_sum_zeroelim(eablen, eab, deblen, deb, temp48a);
+  temp48blen = fast_expansion_sum_zeroelim(abdlen, abd, dealen, dea, temp48b);
+  for (i = 0; i < temp48blen; i++) {
+    temp48b[i] = -temp48b[i];
+  }
+  deablen = fast_expansion_sum_zeroelim(temp48alen, temp48a,
+                                        temp48blen, temp48b, deab);
+  xlen = scale_expansion_zeroelim(deablen, deab, pc[0], temp192);
+  xlen = scale_expansion_zeroelim(xlen, temp192, pc[0], det384x);
+  ylen = scale_expansion_zeroelim(deablen, deab, pc[1], temp192);
+  ylen = scale_expansion_zeroelim(ylen, temp192, pc[1], det384y);
+  zlen = scale_expansion_zeroelim(deablen, deab, pc[2], temp192);
+  zlen = scale_expansion_zeroelim(zlen, temp192, pc[2], det384z);
+  xylen = fast_expansion_sum_zeroelim(xlen, det384x, ylen, det384y, detxy);
+  clen = fast_expansion_sum_zeroelim(xylen, detxy, zlen, det384z, cdet);
+
+  temp48alen = fast_expansion_sum_zeroelim(abclen, abc, eaclen, eac, temp48a);
+  temp48blen = fast_expansion_sum_zeroelim(bcelen, bce, eablen, eab, temp48b);
+  for (i = 0; i < temp48blen; i++) {
+    temp48b[i] = -temp48b[i];
+  }
+  eabclen = fast_expansion_sum_zeroelim(temp48alen, temp48a,
+                                        temp48blen, temp48b, eabc);
+  xlen = scale_expansion_zeroelim(eabclen, eabc, pd[0], temp192);
+  xlen = scale_expansion_zeroelim(xlen, temp192, pd[0], det384x);
+  ylen = scale_expansion_zeroelim(eabclen, eabc, pd[1], temp192);
+  ylen = scale_expansion_zeroelim(ylen, temp192, pd[1], det384y);
+  zlen = scale_expansion_zeroelim(eabclen, eabc, pd[2], temp192);
+  zlen = scale_expansion_zeroelim(zlen, temp192, pd[2], det384z);
+  xylen = fast_expansion_sum_zeroelim(xlen, det384x, ylen, det384y, detxy);
+  dlen = fast_expansion_sum_zeroelim(xylen, detxy, zlen, det384z, ddet);
+
+  temp48alen = fast_expansion_sum_zeroelim(bcdlen, bcd, abdlen, abd, temp48a);
+  temp48blen = fast_expansion_sum_zeroelim(cdalen, cda, abclen, abc, temp48b);
+  for (i = 0; i < temp48blen; i++) {
+    temp48b[i] = -temp48b[i];
+  }
+  abcdlen = fast_expansion_sum_zeroelim(temp48alen, temp48a,
+                                        temp48blen, temp48b, abcd);
+  xlen = scale_expansion_zeroelim(abcdlen, abcd, pe[0], temp192);
+  xlen = scale_expansion_zeroelim(xlen, temp192, pe[0], det384x);
+  ylen = scale_expansion_zeroelim(abcdlen, abcd, pe[1], temp192);
+  ylen = scale_expansion_zeroelim(ylen, temp192, pe[1], det384y);
+  zlen = scale_expansion_zeroelim(abcdlen, abcd, pe[2], temp192);
+  zlen = scale_expansion_zeroelim(zlen, temp192, pe[2], det384z);
+  xylen = fast_expansion_sum_zeroelim(xlen, det384x, ylen, det384y, detxy);
+  elen = fast_expansion_sum_zeroelim(xylen, detxy, zlen, det384z, edet);
+
+  ablen = fast_expansion_sum_zeroelim(alen, adet, blen, bdet, abdet);
+  cdlen = fast_expansion_sum_zeroelim(clen, cdet, dlen, ddet, cddet);
+  cdelen = fast_expansion_sum_zeroelim(cdlen, cddet, elen, edet, cdedet);
+  deterlen = fast_expansion_sum_zeroelim(ablen, abdet, cdelen, cdedet, deter);
+
+  return deter[deterlen - 1];
+}
+
+static REAL insphereadapt(REAL *pa, REAL *pb, REAL *pc, REAL *pd, REAL *pe, 
+			  REAL permanent)
+{
+  INEXACT REAL aex, bex, cex, dex, aey, bey, cey, dey, aez, bez, cez, dez;
+  REAL det, errbound;
+
+  INEXACT REAL aexbey1, bexaey1, bexcey1, cexbey1;
+  INEXACT REAL cexdey1, dexcey1, dexaey1, aexdey1;
+  INEXACT REAL aexcey1, cexaey1, bexdey1, dexbey1;
+  REAL aexbey0, bexaey0, bexcey0, cexbey0;
+  REAL cexdey0, dexcey0, dexaey0, aexdey0;
+  REAL aexcey0, cexaey0, bexdey0, dexbey0;
+  REAL ab[4], bc[4], cd[4], da[4], ac[4], bd[4];
+  INEXACT REAL ab3, bc3, cd3, da3, ac3, bd3;
+  REAL abeps, bceps, cdeps, daeps, aceps, bdeps;
+  REAL temp8a[8], temp8b[8], temp8c[8], temp16[16], temp24[24], temp48[48];
+  int temp8alen, temp8blen, temp8clen, temp16len, temp24len, temp48len;
+  REAL xdet[96], ydet[96], zdet[96], xydet[192];
+  int xlen, ylen, zlen, xylen;
+  REAL adet[288], bdet[288], cdet[288], ddet[288];
+  int alen, blen, clen, dlen;
+  REAL abdet[576], cddet[576];
+  int ablen, cdlen;
+  REAL fin1[1152];
+  int finlength;
+
+  REAL aextail, bextail, cextail, dextail;
+  REAL aeytail, beytail, ceytail, deytail;
+  REAL aeztail, beztail, ceztail, deztail;
+
+  INEXACT REAL bvirt;
+  REAL avirt, bround, around;
+  INEXACT REAL c;
+  INEXACT REAL abig;
+  REAL ahi, alo, bhi, blo;
+  REAL err1, err2, err3;
+  INEXACT REAL _i, _j;
+  REAL _0;
+
+  aex = (REAL) (pa[0] - pe[0]);
+  bex = (REAL) (pb[0] - pe[0]);
+  cex = (REAL) (pc[0] - pe[0]);
+  dex = (REAL) (pd[0] - pe[0]);
+  aey = (REAL) (pa[1] - pe[1]);
+  bey = (REAL) (pb[1] - pe[1]);
+  cey = (REAL) (pc[1] - pe[1]);
+  dey = (REAL) (pd[1] - pe[1]);
+  aez = (REAL) (pa[2] - pe[2]);
+  bez = (REAL) (pb[2] - pe[2]);
+  cez = (REAL) (pc[2] - pe[2]);
+  dez = (REAL) (pd[2] - pe[2]);
+
+  Two_Product(aex, bey, aexbey1, aexbey0);
+  Two_Product(bex, aey, bexaey1, bexaey0);
+  Two_Two_Diff(aexbey1, aexbey0, bexaey1, bexaey0, ab3, ab[2], ab[1], ab[0]);
+  ab[3] = ab3;
+
+  Two_Product(bex, cey, bexcey1, bexcey0);
+  Two_Product(cex, bey, cexbey1, cexbey0);
+  Two_Two_Diff(bexcey1, bexcey0, cexbey1, cexbey0, bc3, bc[2], bc[1], bc[0]);
+  bc[3] = bc3;
+
+  Two_Product(cex, dey, cexdey1, cexdey0);
+  Two_Product(dex, cey, dexcey1, dexcey0);
+  Two_Two_Diff(cexdey1, cexdey0, dexcey1, dexcey0, cd3, cd[2], cd[1], cd[0]);
+  cd[3] = cd3;
+
+  Two_Product(dex, aey, dexaey1, dexaey0);
+  Two_Product(aex, dey, aexdey1, aexdey0);
+  Two_Two_Diff(dexaey1, dexaey0, aexdey1, aexdey0, da3, da[2], da[1], da[0]);
+  da[3] = da3;
+
+  Two_Product(aex, cey, aexcey1, aexcey0);
+  Two_Product(cex, aey, cexaey1, cexaey0);
+  Two_Two_Diff(aexcey1, aexcey0, cexaey1, cexaey0, ac3, ac[2], ac[1], ac[0]);
+  ac[3] = ac3;
+
+  Two_Product(bex, dey, bexdey1, bexdey0);
+  Two_Product(dex, bey, dexbey1, dexbey0);
+  Two_Two_Diff(bexdey1, bexdey0, dexbey1, dexbey0, bd3, bd[2], bd[1], bd[0]);
+  bd[3] = bd3;
+
+  temp8alen = scale_expansion_zeroelim(4, cd, bez, temp8a);
+  temp8blen = scale_expansion_zeroelim(4, bd, -cez, temp8b);
+  temp8clen = scale_expansion_zeroelim(4, bc, dez, temp8c);
+  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a,
+                                          temp8blen, temp8b, temp16);
+  temp24len = fast_expansion_sum_zeroelim(temp8clen, temp8c,
+                                          temp16len, temp16, temp24);
+  temp48len = scale_expansion_zeroelim(temp24len, temp24, aex, temp48);
+  xlen = scale_expansion_zeroelim(temp48len, temp48, -aex, xdet);
+  temp48len = scale_expansion_zeroelim(temp24len, temp24, aey, temp48);
+  ylen = scale_expansion_zeroelim(temp48len, temp48, -aey, ydet);
+  temp48len = scale_expansion_zeroelim(temp24len, temp24, aez, temp48);
+  zlen = scale_expansion_zeroelim(temp48len, temp48, -aez, zdet);
+  xylen = fast_expansion_sum_zeroelim(xlen, xdet, ylen, ydet, xydet);
+  alen = fast_expansion_sum_zeroelim(xylen, xydet, zlen, zdet, adet);
+
+  temp8alen = scale_expansion_zeroelim(4, da, cez, temp8a);
+  temp8blen = scale_expansion_zeroelim(4, ac, dez, temp8b);
+  temp8clen = scale_expansion_zeroelim(4, cd, aez, temp8c);
+  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a,
+                                          temp8blen, temp8b, temp16);
+  temp24len = fast_expansion_sum_zeroelim(temp8clen, temp8c,
+                                          temp16len, temp16, temp24);
+  temp48len = scale_expansion_zeroelim(temp24len, temp24, bex, temp48);
+  xlen = scale_expansion_zeroelim(temp48len, temp48, bex, xdet);
+  temp48len = scale_expansion_zeroelim(temp24len, temp24, bey, temp48);
+  ylen = scale_expansion_zeroelim(temp48len, temp48, bey, ydet);
+  temp48len = scale_expansion_zeroelim(temp24len, temp24, bez, temp48);
+  zlen = scale_expansion_zeroelim(temp48len, temp48, bez, zdet);
+  xylen = fast_expansion_sum_zeroelim(xlen, xdet, ylen, ydet, xydet);
+  blen = fast_expansion_sum_zeroelim(xylen, xydet, zlen, zdet, bdet);
+
+  temp8alen = scale_expansion_zeroelim(4, ab, dez, temp8a);
+  temp8blen = scale_expansion_zeroelim(4, bd, aez, temp8b);
+  temp8clen = scale_expansion_zeroelim(4, da, bez, temp8c);
+  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a,
+                                          temp8blen, temp8b, temp16);
+  temp24len = fast_expansion_sum_zeroelim(temp8clen, temp8c,
+                                          temp16len, temp16, temp24);
+  temp48len = scale_expansion_zeroelim(temp24len, temp24, cex, temp48);
+  xlen = scale_expansion_zeroelim(temp48len, temp48, -cex, xdet);
+  temp48len = scale_expansion_zeroelim(temp24len, temp24, cey, temp48);
+  ylen = scale_expansion_zeroelim(temp48len, temp48, -cey, ydet);
+  temp48len = scale_expansion_zeroelim(temp24len, temp24, cez, temp48);
+  zlen = scale_expansion_zeroelim(temp48len, temp48, -cez, zdet);
+  xylen = fast_expansion_sum_zeroelim(xlen, xdet, ylen, ydet, xydet);
+  clen = fast_expansion_sum_zeroelim(xylen, xydet, zlen, zdet, cdet);
+
+  temp8alen = scale_expansion_zeroelim(4, bc, aez, temp8a);
+  temp8blen = scale_expansion_zeroelim(4, ac, -bez, temp8b);
+  temp8clen = scale_expansion_zeroelim(4, ab, cez, temp8c);
+  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a,
+                                          temp8blen, temp8b, temp16);
+  temp24len = fast_expansion_sum_zeroelim(temp8clen, temp8c,
+                                          temp16len, temp16, temp24);
+  temp48len = scale_expansion_zeroelim(temp24len, temp24, dex, temp48);
+  xlen = scale_expansion_zeroelim(temp48len, temp48, dex, xdet);
+  temp48len = scale_expansion_zeroelim(temp24len, temp24, dey, temp48);
+  ylen = scale_expansion_zeroelim(temp48len, temp48, dey, ydet);
+  temp48len = scale_expansion_zeroelim(temp24len, temp24, dez, temp48);
+  zlen = scale_expansion_zeroelim(temp48len, temp48, dez, zdet);
+  xylen = fast_expansion_sum_zeroelim(xlen, xdet, ylen, ydet, xydet);
+  dlen = fast_expansion_sum_zeroelim(xylen, xydet, zlen, zdet, ddet);
+
+  ablen = fast_expansion_sum_zeroelim(alen, adet, blen, bdet, abdet);
+  cdlen = fast_expansion_sum_zeroelim(clen, cdet, dlen, ddet, cddet);
+  finlength = fast_expansion_sum_zeroelim(ablen, abdet, cdlen, cddet, fin1);
+
+  det = estimate(finlength, fin1);
+  errbound = isperrboundB * permanent;
+  if ((det >= errbound) || (-det >= errbound)) {
+    return det;
+  }
+
+  Two_Diff_Tail(pa[0], pe[0], aex, aextail);
+  Two_Diff_Tail(pa[1], pe[1], aey, aeytail);
+  Two_Diff_Tail(pa[2], pe[2], aez, aeztail);
+  Two_Diff_Tail(pb[0], pe[0], bex, bextail);
+  Two_Diff_Tail(pb[1], pe[1], bey, beytail);
+  Two_Diff_Tail(pb[2], pe[2], bez, beztail);
+  Two_Diff_Tail(pc[0], pe[0], cex, cextail);
+  Two_Diff_Tail(pc[1], pe[1], cey, ceytail);
+  Two_Diff_Tail(pc[2], pe[2], cez, ceztail);
+  Two_Diff_Tail(pd[0], pe[0], dex, dextail);
+  Two_Diff_Tail(pd[1], pe[1], dey, deytail);
+  Two_Diff_Tail(pd[2], pe[2], dez, deztail);
+  if ((aextail == 0.0) && (aeytail == 0.0) && (aeztail == 0.0)
+      && (bextail == 0.0) && (beytail == 0.0) && (beztail == 0.0)
+      && (cextail == 0.0) && (ceytail == 0.0) && (ceztail == 0.0)
+      && (dextail == 0.0) && (deytail == 0.0) && (deztail == 0.0)) {
+    return det;
+  }
+
+  errbound = isperrboundC * permanent + resulterrbound * Absolute(det);
+  abeps = (aex * beytail + bey * aextail)
+        - (aey * bextail + bex * aeytail);
+  bceps = (bex * ceytail + cey * bextail)
+        - (bey * cextail + cex * beytail);
+  cdeps = (cex * deytail + dey * cextail)
+        - (cey * dextail + dex * ceytail);
+  daeps = (dex * aeytail + aey * dextail)
+        - (dey * aextail + aex * deytail);
+  aceps = (aex * ceytail + cey * aextail)
+        - (aey * cextail + cex * aeytail);
+  bdeps = (bex * deytail + dey * bextail)
+        - (bey * dextail + dex * beytail);
+  det += (((bex * bex + bey * bey + bez * bez)
+           * ((cez * daeps + dez * aceps + aez * cdeps)
+              + (ceztail * da3 + deztail * ac3 + aeztail * cd3))
+           + (dex * dex + dey * dey + dez * dez)
+           * ((aez * bceps - bez * aceps + cez * abeps)
+              + (aeztail * bc3 - beztail * ac3 + ceztail * ab3)))
+          - ((aex * aex + aey * aey + aez * aez)
+           * ((bez * cdeps - cez * bdeps + dez * bceps)
+              + (beztail * cd3 - ceztail * bd3 + deztail * bc3))
+           + (cex * cex + cey * cey + cez * cez)
+           * ((dez * abeps + aez * bdeps + bez * daeps)
+              + (deztail * ab3 + aeztail * bd3 + beztail * da3))))
+       + 2.0 * (((bex * bextail + bey * beytail + bez * beztail)
+                 * (cez * da3 + dez * ac3 + aez * cd3)
+                 + (dex * dextail + dey * deytail + dez * deztail)
+                 * (aez * bc3 - bez * ac3 + cez * ab3))
+                - ((aex * aextail + aey * aeytail + aez * aeztail)
+                 * (bez * cd3 - cez * bd3 + dez * bc3)
+                 + (cex * cextail + cey * ceytail + cez * ceztail)
+                 * (dez * ab3 + aez * bd3 + bez * da3)));
+  if ((det >= errbound) || (-det >= errbound)) {
+    return det;
+  }
+
+  return insphereexact(pa, pb, pc, pd, pe);
+}
+
+REAL insphere(pa, pb, pc, pd, pe)
+REAL *pa;
+REAL *pb;
+REAL *pc;
+REAL *pd;
+REAL *pe;
+{
+  REAL aex, bex, cex, dex;
+  REAL aey, bey, cey, dey;
+  REAL aez, bez, cez, dez;
+  REAL aexbey, bexaey, bexcey, cexbey, cexdey, dexcey, dexaey, aexdey;
+  REAL aexcey, cexaey, bexdey, dexbey;
+  REAL alift, blift, clift, dlift;
+  REAL ab, bc, cd, da, ac, bd;
+  REAL abc, bcd, cda, dab;
+  REAL aezplus, bezplus, cezplus, dezplus;
+  REAL aexbeyplus, bexaeyplus, bexceyplus, cexbeyplus;
+  REAL cexdeyplus, dexceyplus, dexaeyplus, aexdeyplus;
+  REAL aexceyplus, cexaeyplus, bexdeyplus, dexbeyplus;
+  REAL det;
+  REAL permanent, errbound;
+  REAL ins;
+
+  FPU_ROUND_DOUBLE;
+
+  aex = pa[0] - pe[0];
+  bex = pb[0] - pe[0];
+  cex = pc[0] - pe[0];
+  dex = pd[0] - pe[0];
+  aey = pa[1] - pe[1];
+  bey = pb[1] - pe[1];
+  cey = pc[1] - pe[1];
+  dey = pd[1] - pe[1];
+  aez = pa[2] - pe[2];
+  bez = pb[2] - pe[2];
+  cez = pc[2] - pe[2];
+  dez = pd[2] - pe[2];
+
+  aexbey = aex * bey;
+  bexaey = bex * aey;
+  ab = aexbey - bexaey;
+  bexcey = bex * cey;
+  cexbey = cex * bey;
+  bc = bexcey - cexbey;
+  cexdey = cex * dey;
+  dexcey = dex * cey;
+  cd = cexdey - dexcey;
+  dexaey = dex * aey;
+  aexdey = aex * dey;
+  da = dexaey - aexdey;
+
+  aexcey = aex * cey;
+  cexaey = cex * aey;
+  ac = aexcey - cexaey;
+  bexdey = bex * dey;
+  dexbey = dex * bey;
+  bd = bexdey - dexbey;
+
+  abc = aez * bc - bez * ac + cez * ab;
+  bcd = bez * cd - cez * bd + dez * bc;
+  cda = cez * da + dez * ac + aez * cd;
+  dab = dez * ab + aez * bd + bez * da;
+
+  alift = aex * aex + aey * aey + aez * aez;
+  blift = bex * bex + bey * bey + bez * bez;
+  clift = cex * cex + cey * cey + cez * cez;
+  dlift = dex * dex + dey * dey + dez * dez;
+
+  det = (dlift * abc - clift * dab) + (blift * cda - alift * bcd);
+
+  aezplus = Absolute(aez);
+  bezplus = Absolute(bez);
+  cezplus = Absolute(cez);
+  dezplus = Absolute(dez);
+  aexbeyplus = Absolute(aexbey);
+  bexaeyplus = Absolute(bexaey);
+  bexceyplus = Absolute(bexcey);
+  cexbeyplus = Absolute(cexbey);
+  cexdeyplus = Absolute(cexdey);
+  dexceyplus = Absolute(dexcey);
+  dexaeyplus = Absolute(dexaey);
+  aexdeyplus = Absolute(aexdey);
+  aexceyplus = Absolute(aexcey);
+  cexaeyplus = Absolute(cexaey);
+  bexdeyplus = Absolute(bexdey);
+  dexbeyplus = Absolute(dexbey);
+  permanent = ((cexdeyplus + dexceyplus) * bezplus
+               + (dexbeyplus + bexdeyplus) * cezplus
+               + (bexceyplus + cexbeyplus) * dezplus)
+            * alift
+            + ((dexaeyplus + aexdeyplus) * cezplus
+               + (aexceyplus + cexaeyplus) * dezplus
+               + (cexdeyplus + dexceyplus) * aezplus)
+            * blift
+            + ((aexbeyplus + bexaeyplus) * dezplus
+               + (bexdeyplus + dexbeyplus) * aezplus
+               + (dexaeyplus + aexdeyplus) * bezplus)
+            * clift
+            + ((bexceyplus + cexbeyplus) * aezplus
+               + (cexaeyplus + aexceyplus) * bezplus
+               + (aexbeyplus + bexaeyplus) * cezplus)
+            * dlift;
+  errbound = isperrboundA * permanent;
+  if ((det > errbound) || (-det > errbound)) {
+    FPU_RESTORE;
+    return det;
+  }
+
+  ins = insphereadapt(pa, pb, pc, pd, pe, permanent);
+  FPU_RESTORE;
+  return ins;
+}
diff --git a/gts/predicates.h b/gts/predicates.h
new file mode 100644
index 0000000..8b026ed
--- /dev/null
+++ b/gts/predicates.h
@@ -0,0 +1,41 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+/* Header file for robust predicates by Jonathan Richard Shewchuk */
+
+#ifndef __PREDICATES_H__
+#define __PREDICATES_H__
+
+double orient2d            (double * pa,
+			    double * pb,
+			    double * pc);
+double orient3d            (double * pa,
+			    double * pb,
+			    double * pc,
+			    double * pd);
+double incircle            (double * pa,
+			    double * pb,
+			    double * pc,
+			    double * pd);
+double insphere            (double * pa,
+			    double * pb,
+			    double * pc,
+			    double * pd,
+			    double * pe);
+
+#endif /* __PREDICATES_H__ */
diff --git a/gts/psurface.c b/gts/psurface.c
new file mode 100644
index 0000000..6db3ae2
--- /dev/null
+++ b/gts/psurface.c
@@ -0,0 +1,471 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <stdlib.h>
+#include <math.h>
+#include "gts.h"
+
+#define HEAP_INSERT_OBJECT(h, e) (GTS_OBJECT (e)->reserved =\
+                                   gts_eheap_insert (h, e))
+#define HEAP_REMOVE_OBJECT(h, e) (gts_eheap_remove (h, GTS_OBJECT (e)->reserved),\
+				  GTS_OBJECT (e)->reserved = NULL)
+
+static void psurface_destroy (GtsObject * object)
+{
+  GtsPSurface * ps = GTS_PSURFACE (object);
+  guint i;
+
+  if (!GTS_PSURFACE_IS_CLOSED (ps))
+    gts_psurface_close (ps);
+
+  for (i = 0; i < ps->split->len; i++)
+    if (g_ptr_array_index (ps->split, i))
+      gts_object_destroy (GTS_OBJECT (g_ptr_array_index (ps->split, i)));
+  g_ptr_array_free (ps->split, TRUE);
+
+  (* GTS_OBJECT_CLASS (gts_psurface_class ())->parent_class->destroy) (object);
+}
+
+static void psurface_class_init (GtsObjectClass * klass)
+{
+  klass->destroy = psurface_destroy;
+}
+
+static void psurface_init (GtsPSurface * psurface)
+{
+  psurface->s = NULL;
+  psurface->split = g_ptr_array_new ();
+  psurface->split_class = gts_split_class ();
+  psurface->pos = psurface->min = 0;
+  psurface->vertices = psurface->faces = NULL;
+}
+
+/**
+ * gts_psurface_class:
+ * 
+ * Returns: the #GtsPSurfaceClass.
+ */
+GtsPSurfaceClass * gts_psurface_class (void)
+{
+  static GtsPSurfaceClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo psurface_info = {
+      "GtsPSurface",
+      sizeof (GtsPSurface),
+      sizeof (GtsPSurfaceClass),
+      (GtsObjectClassInitFunc) psurface_class_init,
+      (GtsObjectInitFunc) psurface_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (gts_object_class (), 
+				  &psurface_info);
+  }
+
+  return klass;
+}
+
+static GtsVertex * edge_collapse (GtsPSurface * ps,
+				  GtsEdge * e,
+				  GtsEHeap * heap,
+				  GtsCoarsenFunc coarsen_func,
+				  gpointer coarsen_data,
+				  gdouble maxcosine2)
+{
+  GtsVertex  * v1 = GTS_SEGMENT (e)->v1, * v2 = GTS_SEGMENT (e)->v2, * mid;
+  GtsSplit * vs;
+  GtsObject * o1, * o2;
+
+  /* if the edge is degenerate (i.e. v1 == v2), destroy and return */
+  if (v1 == v2) {
+    gts_object_destroy (GTS_OBJECT (e));
+    return NULL;
+  }
+
+  if (!gts_edge_collapse_is_valid (e) ||
+      /* check that a non-manifold edge is not a contact edge */
+      (g_slist_length (e->triangles) > 2 && gts_edge_is_contact (e) > 1)) {
+    GTS_OBJECT (e)->reserved = 
+      gts_eheap_insert_with_key (heap, e, G_MAXDOUBLE);
+    return NULL;
+  }
+
+  mid = (*coarsen_func) (e, ps->s->vertex_class, coarsen_data);
+
+  if (gts_edge_collapse_creates_fold (e, mid, maxcosine2)) {
+    GTS_OBJECT (e)->reserved = 
+      gts_eheap_insert_with_key (heap, e, G_MAXDOUBLE);
+    gts_object_destroy (GTS_OBJECT (mid));
+    return NULL;
+  }
+
+  if (GTS_OBJECT (v1)->reserved)
+    o1 = GTS_OBJECT (v1)->reserved;
+  else
+    o1 = GTS_OBJECT (v1);
+  if (GTS_OBJECT (v2)->reserved)
+    o2 = GTS_OBJECT (v2)->reserved;
+  else
+    o2 = GTS_OBJECT (v2);
+  vs = gts_split_new (ps->split_class, mid, o1, o2);
+  gts_split_collapse (vs, ps->s->edge_class, heap);
+  GTS_OBJECT (vs->v)->reserved = vs;
+  g_ptr_array_add (ps->split, vs);
+
+  return mid;
+}
+
+static void update_2nd_closest_neighbors (GtsVertex * v, GtsEHeap * heap)
+{
+  GSList * i = v->segments;
+  GSList * list = NULL;
+  
+  while (i) {
+    GtsSegment * s = i->data;
+    if (GTS_IS_EDGE (s)) {
+      GtsVertex * v1 = s->v1 == v ? s->v2 : s->v1;
+      GSList * j = v1->segments;
+      while (j) {
+	GtsSegment * s1 = j->data;
+	if (GTS_IS_EDGE (s1) && !g_slist_find (list, s1))
+	  list = g_slist_prepend (list, s1);
+	j = j->next;
+      }
+    }
+    i = i->next;
+  }
+
+  i = list;
+  while (i) {
+    GtsEdge * e = i->data;
+    if (GTS_OBJECT (e)->reserved)
+      HEAP_REMOVE_OBJECT (heap, e);
+    HEAP_INSERT_OBJECT (heap, e);
+    i = i->next;
+  }
+
+  g_slist_free (list);
+}
+
+static gdouble edge_length2 (GtsEdge * e)
+{
+  return gts_point_distance2 (GTS_POINT (GTS_SEGMENT (e)->v1), 
+			      GTS_POINT (GTS_SEGMENT (e)->v2));
+}
+
+static void create_heap_coarsen (GtsEdge * e, GtsEHeap * heap)
+{
+  HEAP_INSERT_OBJECT (heap, e);
+}
+
+/* #define DEBUG_FOLD */
+/* #define DEBUG_CONTACT_VERTEX */
+
+#ifdef DEBUG_FOLD
+static void check_fold (GtsTriangle * t, gdouble * maxcosine2)
+{
+  GtsEdge * e1 = t->e1, * e2 = t->e2, * e3 = t->e3;
+
+  
+  if (gts_triangles_are_folded (e1->triangles, 
+				GTS_SEGMENT (e1)->v1,
+				GTS_SEGMENT (e1)->v2,
+				*maxcosine2) ||
+      gts_triangles_are_folded (e2->triangles, 
+				GTS_SEGMENT (e2)->v1,
+				GTS_SEGMENT (e2)->v2,
+				*maxcosine2) ||
+      gts_triangles_are_folded (e3->triangles, 
+				GTS_SEGMENT (e3)->v1,
+				GTS_SEGMENT (e3)->v2,
+				*maxcosine2)) {
+    fprintf (stderr, "triangle %p:(%p,%p,%p) is folded\n", t, e1, e2, e3);
+    g_assert_not_reached ();
+  }
+}
+#endif
+
+/**
+ * gts_psurface_new:
+ * @klass: a #GtsPSurfaceClass.
+ * @surface: a #GtsSurface.
+ * @split_class: a #GtsSplitClass to use for the new progressive surface.
+ * @cost_func: cost function for the edge collapse algorithm.
+ * @cost_data: data to pass to @cost_func.
+ * @coarsen_func: the function returning the vertex replacement for the edge 
+ * collapse.
+ * @coarsen_data: data to pass to @coarsen_func.
+ * @stop_func: the function to call to decide whether to stop the coarsening
+ * process.
+ * @stop_data: data to pass to @stop_func.
+ * @minangle: the minimum angle allowable between two neighboring triangles. 
+ * This is used to avoid introducing folds in the mesh during simplification.
+ *
+ * This function works in exactly the same way as the
+ * gts_surface_coarsen() function, except that the history of edge
+ * collapse is saved in an array of #GtsSplit objects. This allows for
+ * dynamic continuous multiresolution control of the input @surface.
+ *
+ * Returns: a new progressive surface.
+ */
+GtsPSurface * gts_psurface_new (GtsPSurfaceClass * klass,
+				GtsSurface * surface,
+				GtsSplitClass * split_class,
+				GtsKeyFunc cost_func,
+				gpointer cost_data,
+				GtsCoarsenFunc coarsen_func,
+				gpointer coarsen_data,
+				GtsStopFunc stop_func,
+				gpointer stop_data,
+				gdouble minangle)
+{
+  GtsPSurface * psurface;
+  GtsEHeap * heap;
+  GtsEdge * e;
+  gdouble top_cost, maxcosine2;
+  guint i;
+
+  g_return_val_if_fail (klass != NULL, NULL);
+  g_return_val_if_fail (surface != NULL, NULL);
+  g_return_val_if_fail (split_class != NULL, NULL);
+  g_return_val_if_fail (stop_func != NULL, NULL);
+
+  psurface = GTS_PSURFACE (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  psurface->s = surface;
+  psurface->split_class = split_class;
+
+  if (cost_func == NULL)
+    cost_func = (GtsKeyFunc) edge_length2;
+  if (coarsen_func == NULL)
+    coarsen_func = (GtsCoarsenFunc) gts_segment_midvertex;
+
+  heap = gts_eheap_new (cost_func, cost_data);
+  maxcosine2 = cos (minangle); maxcosine2 *= maxcosine2;
+
+  gts_eheap_freeze (heap);
+  gts_surface_foreach_edge (surface, (GtsFunc) create_heap_coarsen, heap);
+  gts_eheap_thaw (heap);
+  /* we want to control edge destruction manually */
+  gts_allow_floating_edges = TRUE;
+  while ((e = gts_eheap_remove_top (heap, &top_cost)) &&
+	 (top_cost < G_MAXDOUBLE) &&
+	 !(*stop_func) (top_cost, gts_eheap_size (heap) - 
+			gts_edge_face_number (e, surface), stop_data)) {
+    GtsVertex * v = edge_collapse (psurface, e, heap, 
+				   coarsen_func, coarsen_data, maxcosine2);
+    if (v != NULL) {
+      update_2nd_closest_neighbors (v, heap);
+#ifdef DEBUG_FOLD
+      {
+	GSList * triangles = gts_vertex_triangles (v, NULL), * i;
+	fprintf (stderr, "\n---- Check for folds ----\n%p: ", v);
+	i = triangles;
+	while (i) {
+	  GtsTriangle * t = i->data;
+	  fprintf (stderr, "%p:(%p,%p,%p) ", t, t->e1, t->e2, t->e3);
+	  i = i->next;
+	}
+	fprintf (stderr, "\n");
+	g_slist_free (triangles);
+	gts_surface_foreach_face (surface, (GtsFunc) check_fold, &maxcosine2);
+      }
+#endif
+#ifdef DEBUG_CONTACT_VERTEX
+      if (gts_vertex_is_contact (v, FALSE) != 1) {
+	FILE * fptr = fopen ("after", "wt");
+	GSList * triangles = gts_vertex_triangles (v, NULL), * i;
+
+	fprintf (stderr, "collapse of %p created a contact vertex\n", e);
+		 
+	fprintf (fptr, 
+		 "(geometry \"sphere\" { = SPHERE 0.1 0. 0. 0. })\n"
+		 "(normalization \"sphere\" none)\n");
+	i = triangles;
+	while (i) {
+	  gts_write_triangle (i->data, GTS_POINT (v), fptr);
+	  i = i->next;
+	}
+	g_assert_not_reached ();
+      }
+#endif
+    }
+  }
+  gts_allow_floating_edges = FALSE;
+
+  /* set reserved field of remaining edges back to NULL */
+  if (e) GTS_OBJECT (e)->reserved = NULL;
+  gts_eheap_foreach (heap, (GFunc) gts_object_reset_reserved, NULL);
+
+  gts_eheap_destroy (heap);
+
+  psurface->pos = psurface->split->len;
+  psurface->min = gts_surface_vertex_number (psurface->s);
+
+  /* set reserved field of vertices (used to build the hierarchy) 
+     back to NULL */
+  for (i = 0; i < psurface->split->len; i++) {
+    GtsSplit * vs = g_ptr_array_index (psurface->split, i);
+    gts_object_reset_reserved (GTS_OBJECT (vs->v));
+  }
+
+  return psurface;
+}
+
+/**
+ * gts_psurface_add_vertex:
+ * @ps: a #GtsPSurface.
+ *
+ * Adds a vertex to the progressive surface @ps by expanding the next
+ * available #GtsSplit.
+ *
+ * Returns: the expanded #GtsSplit or %NULL if all the #GtsSplit have already
+ * been expanded.
+ */
+GtsSplit * gts_psurface_add_vertex (GtsPSurface * ps) 
+{ 
+  GtsSplit * vs;
+
+  g_return_val_if_fail (ps != NULL, NULL);
+  g_return_val_if_fail (GTS_PSURFACE_IS_CLOSED (ps), NULL);
+
+  if (ps->pos == 0)
+    return NULL;
+
+  vs = g_ptr_array_index (ps->split, --ps->pos);
+  gts_split_expand (vs, ps->s, ps->s->edge_class);
+
+  return vs;
+}
+
+/**
+ * gts_psurface_remove_vertex:
+ * @ps: a #GtsPSurface.
+ *
+ * Removes one vertex from the progressive surface @ps by collapsing the first
+ * available #GtsSplit.
+ *
+ * Returns: the collapsed #GtsSplit or %NULL if all the #GtsSplit have already
+ * been collapsed.
+ */
+GtsSplit * gts_psurface_remove_vertex (GtsPSurface * ps)
+{
+  GtsSplit * vs;
+
+  g_return_val_if_fail (ps != NULL, NULL);
+  g_return_val_if_fail (GTS_PSURFACE_IS_CLOSED (ps), NULL);
+
+  if (ps->pos == ps->split->len)
+    return NULL;
+
+  vs = g_ptr_array_index (ps->split, ps->pos++);
+  gts_split_collapse (vs, ps->s->edge_class, NULL);
+
+  return vs;
+}
+
+/**
+ * gts_psurface_max_vertex_number:
+ * @ps: a #GtsPSurface.
+ *
+ * Returns: the maximum number of vertices of @ps i.e. the number of vertices
+ * if all the #GtsSplit were expanded.
+ */
+guint gts_psurface_max_vertex_number (GtsPSurface * ps)
+{
+  g_return_val_if_fail (ps != NULL, 0);
+
+  return ps->min + ps->split->len;
+}
+
+/**
+ * gts_psurface_min_vertex_number:
+ * @ps: a #GtsPSurface.
+ *
+ * Returns: the minimum number of vertices of @ps i.e. the number of vertices
+ * if all the #GtsSplit were collapsed.
+ */
+guint gts_psurface_min_vertex_number (GtsPSurface * ps)
+{
+  g_return_val_if_fail (ps != NULL, 0);
+
+  return ps->min;
+}
+
+/**
+ * gts_psurface_set_vertex_number:
+ * @ps: a #GtsPSurface.
+ * @n: a number of vertices.
+ *
+ * Performs the required number of collapses or expansions to set the number
+ * of vertices of @ps to @n.
+ */
+void gts_psurface_set_vertex_number (GtsPSurface * ps, guint n)
+{
+  g_return_if_fail (ps != NULL);
+  g_return_if_fail (GTS_PSURFACE_IS_CLOSED (ps));
+
+  n = ps->min + ps->split->len - n;
+  while (ps->pos > n && gts_psurface_add_vertex (ps))
+    ;
+  while (ps->pos < n && gts_psurface_remove_vertex (ps))
+    ;
+}
+
+/**
+ * gts_psurface_get_vertex_number:
+ * @ps: a #GtsPSurface.
+ *
+ * Returns: the current number of vertices of @ps.
+ */
+guint gts_psurface_get_vertex_number (GtsPSurface * ps)
+{
+  g_return_val_if_fail (ps != NULL, 0);
+  
+  if (!GTS_PSURFACE_IS_CLOSED (ps))
+    return ps->min + ps->pos;
+  else
+    return ps->min + ps->split->len - ps->pos;
+}
+
+/**
+ * gts_psurface_foreach_vertex:
+ * @ps: a #GtsPSurface.
+ * @func: a function to call for each vertex of @ps.
+ * @data: data to be passed to @func.
+ *
+ * Calls @func for each (potential) vertex of @ps, whether actually used
+ * or not. The vertices are called in the order they were created during the
+ * edge collapse operation.
+ */
+void gts_psurface_foreach_vertex (GtsPSurface * ps, 
+				  GtsFunc func, 
+				  gpointer data)
+{
+  guint i;
+
+  g_return_if_fail (ps != NULL);
+  g_return_if_fail (func != NULL);
+  g_return_if_fail (GTS_PSURFACE_IS_CLOSED (ps));
+  
+  for (i = 0; i < ps->split->len; i++) {
+    GtsSplit * vs = g_ptr_array_index (ps->split, i);
+    (*func) (vs->v, data);
+  }
+}
diff --git a/gts/refine.c b/gts/refine.c
new file mode 100644
index 0000000..293eb11
--- /dev/null
+++ b/gts/refine.c
@@ -0,0 +1,418 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <math.h>
+#include "gts.h"
+
+/**
+ * gts_vertex_encroaches_edge:
+ * @v: a #GtsVertex.
+ * @e: a #GtsEdge.
+ *
+ * Returns: %TRUE if @v is strictly contained in the diametral circle of @e,
+ * %FALSE otherwise.
+ */
+gboolean gts_vertex_encroaches_edge (GtsVertex * v, GtsEdge * e)
+{
+  GtsPoint * p, * p1, * p2;
+
+  g_return_val_if_fail (v != NULL, FALSE);
+  g_return_val_if_fail (e != NULL, FALSE);
+
+  p = GTS_POINT (v);
+  p1 = GTS_POINT (GTS_SEGMENT (e)->v1);
+  p2 = GTS_POINT (GTS_SEGMENT (e)->v2);
+
+  if ((p1->x - p->x)*(p2->x - p->x) + (p1->y - p->y)*(p2->y - p->y) < 0.0)
+    return TRUE;
+  return FALSE;
+}
+
+/**
+ * gts_edge_is_encroached:
+ * @e: a #GtsEdge.
+ * @s: a #GtsSurface describing a (constrained) Delaunay triangulation.
+ * @encroaches: a #GtsEncroachFunc.
+ * @data: user data to be passed to @encroaches.
+ *
+ * Returns: a #GtsVertex belonging to @s and encroaching upon @e
+ * (as defined by @encroaches) or %NULL if there is none.  
+ */
+GtsVertex * gts_edge_is_encroached (GtsEdge * e,
+				    GtsSurface * s,
+				    GtsEncroachFunc encroaches,
+				    gpointer data)
+{
+  GSList * i;
+
+  g_return_val_if_fail (e != NULL, NULL);
+  g_return_val_if_fail (s != NULL, NULL);
+  g_return_val_if_fail (encroaches != NULL, NULL);
+
+  i = e->triangles;
+  while (i) {
+    GtsFace * f = i->data;
+    if (GTS_IS_FACE (f) && gts_face_has_parent_surface (f, s)) {
+      GtsVertex * v = gts_triangle_vertex_opposite (GTS_TRIANGLE (f), e);
+      if ((* encroaches) (v, e, s, data))
+	return v;
+    }
+    i = i->next;
+  }
+
+  return NULL;
+}
+
+#define ALREADY_ENCROACHED(c) (GTS_OBJECT (c)->reserved)
+
+static void vertex_encroaches (GtsVertex * v,
+			       GtsSurface * surface,
+			       GtsFifo * encroached,
+			       GtsEncroachFunc encroaches,
+			       gpointer data)
+{
+  GSList * triangles, * i;
+
+  g_return_if_fail (v != NULL);
+  g_return_if_fail (surface != NULL);
+  g_return_if_fail (encroached != NULL);
+  g_return_if_fail (encroaches != NULL);
+
+  i = triangles = gts_vertex_triangles (v, NULL);
+  while (i) {
+    GtsFace * f = i->data;
+    if (GTS_IS_FACE (f) && gts_face_has_parent_surface (f, surface)) {
+      GtsEdge * e = gts_triangle_edge_opposite (i->data, v);
+      if (!ALREADY_ENCROACHED (e) && 
+	  GTS_IS_CONSTRAINT (e) &&
+	  (* encroaches) (v, e, surface, data)) {
+	gts_fifo_push (encroached, e);
+	ALREADY_ENCROACHED (e) = encroached;
+      }
+    }
+    i = i->next;
+  }
+  g_slist_free (triangles);
+}
+
+static void make_encroached_fifo (GtsEdge * e, gpointer * datas)
+{
+  GtsFifo * fifo = datas[0];
+  GtsSurface * s = datas[1];
+  GtsEncroachFunc encroaches = (GtsEncroachFunc) datas[2];
+  gpointer data = datas[3];
+
+  if (GTS_IS_CONSTRAINT (e) && 
+      gts_edge_is_encroached (e, s, encroaches, data)) {
+    gts_fifo_push (fifo, e);
+    ALREADY_ENCROACHED (e) = fifo;
+  }
+}
+
+#define SQUARE_ROOT_TWO 1.41421356237309504880168872420969807856967187
+#define DISTANCE_2D(v1, v2) (sqrt ((GTS_POINT (v2)->x - GTS_POINT (v1)->x)*\
+                                   (GTS_POINT (v2)->x - GTS_POINT (v1)->x) +\
+                                   (GTS_POINT (v2)->y - GTS_POINT (v1)->y)*\
+                                   (GTS_POINT (v2)->y - GTS_POINT (v1)->y)))
+
+/* finds where to split the given edge to avoid infinite cycles. (see
+   Shewchuk's thesis for details */
+static GtsVertex * split_edge (GtsEdge * e,
+			       GtsSurface * surface)
+{
+  GSList * i = e->triangles;
+  GtsEdge * c = NULL;
+
+  /* look for constraints touching e */
+  while (i && !c) {
+    GtsTriangle * t = i->data;
+    if (GTS_IS_FACE (t) && 
+	gts_face_has_parent_surface (GTS_FACE (t), surface)) {
+      GtsEdge * e1, * e2;
+      if (t->e1 == e) { e1 = t->e2; e2 = t->e3; }
+      else if (t->e2 == e) { e1 = t->e1; e2 = t->e3; }
+      else { e1 = t->e1; e2 = t->e2; }
+      if (GTS_IS_CONSTRAINT (e1) && !GTS_IS_CONSTRAINT (e2))
+	c = e1;
+      else if (GTS_IS_CONSTRAINT (e2) && !GTS_IS_CONSTRAINT (e1))
+	c = e2;
+    }
+    i = i->next;
+  }
+  if (c) {
+    /* use power of two concentric shells */
+    GtsVertex * v1 = GTS_SEGMENT (e)->v1;
+    GtsVertex * v2 = GTS_SEGMENT (e)->v2;
+    gdouble l = DISTANCE_2D (v1, v2);
+    gdouble nearestpower = 1., split;
+
+    while (l > SQUARE_ROOT_TWO*nearestpower)
+      nearestpower *= 2.;
+    while (l < SQUARE_ROOT_TWO*nearestpower/2.)
+      nearestpower /= 2.;
+    split = nearestpower/l/2.;
+
+    if (GTS_SEGMENT (c)->v1 == v2 || GTS_SEGMENT (c)->v2 == v2)
+      split = 1. - split;
+    return gts_vertex_new (surface->vertex_class,
+			   (1. - split)*GTS_POINT (v1)->x +
+			   split*GTS_POINT (v2)->x,
+			   (1. - split)*GTS_POINT (v1)->y +
+			   split*GTS_POINT (v2)->y,
+			   (1. - split)*GTS_POINT (v1)->z +
+			   split*GTS_POINT (v2)->z);
+  }
+  else
+    return gts_segment_midvertex (GTS_SEGMENT (e), surface->vertex_class);
+}
+
+static gint split_encroached (GtsSurface * surface, 
+			      GtsFifo * encroached,
+			      gint steiner_max,
+			      GtsEncroachFunc encroaches,
+			      gpointer data)
+{
+  GtsSegment * s;
+
+  while (steiner_max-- != 0 && (s = gts_fifo_pop (encroached))) {
+    GtsVertex * v = split_edge (GTS_EDGE (s), surface);
+    GtsFace * boundary = gts_edge_is_boundary (GTS_EDGE (s), surface);
+    GtsFace * f = boundary;
+#if 1
+    GtsEdge * e1 = GTS_EDGE (gts_object_clone (GTS_OBJECT (s)));
+    GtsEdge * e2 = GTS_EDGE (gts_object_clone (GTS_OBJECT (s)));
+
+    GTS_SEGMENT (e1)->v1 = s->v1;
+    s->v1->segments = g_slist_prepend (s->v1->segments, e1);
+    GTS_SEGMENT (e1)->v2 = v;
+    v->segments = g_slist_prepend (v->segments, e1);
+
+    GTS_SEGMENT (e2)->v1 = v;
+    v->segments = g_slist_prepend (v->segments, e2);
+    GTS_SEGMENT (e2)->v2 = s->v2;
+    s->v2->segments = g_slist_prepend (s->v2->segments, e2);
+#else
+    GtsEdge * e1 = gts_edge_new (GTS_EDGE_CLASS (GTS_OBJECT (s)->klass),
+				 s->v1, v);
+    GtsEdge * e2 = gts_edge_new (GTS_EDGE_CLASS (GTS_OBJECT (s)->klass),
+				 v, s->v2);
+#endif
+
+    GTS_OBJECT (s)->klass = GTS_OBJECT_CLASS (surface->edge_class);
+
+    if (f == NULL)
+      g_assert ((f = gts_edge_has_parent_surface (GTS_EDGE (s), surface)));
+    g_assert (gts_delaunay_add_vertex_to_face (surface, v, f) == NULL);
+
+    if (boundary)
+      gts_object_destroy (GTS_OBJECT (s));
+
+    vertex_encroaches (v, surface, encroached, encroaches, data);
+
+    if (gts_edge_is_encroached (e1, surface, encroaches, data)) {
+      gts_fifo_push (encroached, e1);
+      ALREADY_ENCROACHED (e1) = encroached;
+    }
+    if (gts_edge_is_encroached (e2, surface, encroaches, data)) {
+      gts_fifo_push (encroached, e2);
+      ALREADY_ENCROACHED (e2) = encroached;
+    }
+  }
+
+  return steiner_max;
+}
+
+/**
+ * gts_delaunay_conform:
+ * @surface: a #GtsSurface describing a constrained Delaunay triangulation.
+ * @steiner_max: maximum number of Steiner points.
+ * @encroaches: a #GtsEncroachFunc.
+ * @data: user-data to pass to @encroaches.
+ *
+ * Recursively split constraints of @surface which are encroached by
+ * vertices of @surface (see Shewchuk 96 for details). The split
+ * constraints are destroyed and replaced by a set of new constraints
+ * of the same class. If gts_vertex_encroaches_edge() is used for
+ * @encroaches, the resulting surface will be Delaunay conforming.
+ *
+ * If @steiner_max is positive or nul, the recursive splitting
+ * procedure will stop when this maximum number of Steiner points is
+ * reached. In that case the resulting surface will not necessarily be
+ * Delaunay conforming.
+ *
+ * Returns: the number of remaining encroached edges. If @steiner_max
+ * is set to a negative value and gts_vertex_encroaches_edge() is used
+ * for @encroaches this should always be zero. 
+ */
+guint gts_delaunay_conform (GtsSurface * surface,
+			    gint steiner_max,
+			    GtsEncroachFunc encroaches,
+			    gpointer data)
+{
+  GtsFifo * encroached;
+  gpointer datas[4];
+  guint encroached_number;
+
+  g_return_val_if_fail (surface != NULL, 0);
+  g_return_val_if_fail (surface != NULL, 0);
+  g_return_val_if_fail (encroaches != NULL, 0);
+
+  datas[0] = encroached = gts_fifo_new ();
+  datas[1] = surface;
+  datas[2] = encroaches;
+  datas[3] = data;
+  gts_surface_foreach_edge (surface, (GtsFunc) make_encroached_fifo, datas);
+
+  split_encroached (surface, 
+		    encroached, 
+		    steiner_max,
+		    encroaches, data);
+  gts_fifo_foreach (encroached, (GtsFunc) gts_object_reset_reserved, NULL);
+  encroached_number = gts_fifo_size (encroached);
+  gts_fifo_destroy (encroached);
+  return encroached_number;
+}
+
+#define EHEAP_PAIR(f) (GTS_OBJECT (f)->reserved)
+
+static void heap_surface_add_face (GtsSurface * s, GtsFace * f)
+{
+  GtsEHeap * heap = GTS_OBJECT (s)->reserved;
+  gdouble key = gts_eheap_key (heap, f);
+
+  if (key != 0.)
+    EHEAP_PAIR (f) = gts_eheap_insert_with_key (heap, f, key);
+  
+  if (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass->parent_class)->add_face)
+    (* GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass->parent_class)->add_face) 
+      (s, f);
+}
+
+static void heap_surface_remove_face (GtsSurface * s, GtsFace * f)
+{
+  GtsEHeap * heap = GTS_OBJECT (s)->reserved;
+
+  if (EHEAP_PAIR (f))
+    gts_eheap_remove (heap, EHEAP_PAIR (f));
+
+  if (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass->parent_class)->remove_face)
+    (* GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass->parent_class)->remove_face) 
+      (s, f);
+}
+
+static void heap_surface_class_init (GtsSurfaceClass * klass)
+{
+  klass->add_face = heap_surface_add_face;
+  klass->remove_face = heap_surface_remove_face;
+}
+
+static GtsObjectClass * heap_surface_class_new (GtsObjectClass * parent_class)
+{
+  GtsObjectClassInfo heap_surface_info;
+
+  heap_surface_info = parent_class->info;
+  heap_surface_info.class_init_func = (GtsObjectClassInitFunc)
+    heap_surface_class_init;
+  return gts_object_class_new (parent_class,
+			       &heap_surface_info);
+}
+
+static void make_face_heap (GtsFace * f, GtsEHeap * heap)
+{
+  gdouble key = gts_eheap_key (heap, f);
+
+  if (key != 0.)
+    EHEAP_PAIR (f) = gts_eheap_insert_with_key (heap, f, key);
+}
+
+/**
+ * gts_delaunay_refine:
+ * @surface: a #GtsSurface describing a conforming Delaunay triangulation.
+ * @steiner_max: maximum number of Steiner points.
+ * @encroaches: a #GtsEncroachFunc.
+ * @encroach_data: user-data to pass to @encroaches.
+ * @cost: a #GtsKeyFunc used to sort the faces during refinement.
+ * @cost_data: user-data to pass to @cost.
+ *
+ * An implementation of the refinement algorithm described in Ruppert
+ * (1995) and Shewchuk (1996).
+ * 
+ * Returns: the number of unrefined faces of @surface left. Should be zero
+ * if @steiner_max is set to a negative value.
+ */
+guint gts_delaunay_refine (GtsSurface * surface,
+			   gint steiner_max,
+			   GtsEncroachFunc encroaches,
+			   gpointer encroach_data,
+			   GtsKeyFunc cost,
+			   gpointer cost_data)
+{
+  GtsObjectClass * heap_surface_class;
+  GtsObjectClass * original_class;
+  GtsEHeap * heap;
+  GtsFifo * encroached;
+  GtsFace * f;
+  guint unrefined_number;
+
+  g_return_val_if_fail (surface != NULL, 0);
+  g_return_val_if_fail (encroaches != NULL, 0);
+  g_return_val_if_fail (cost != NULL, 0);
+
+  original_class = GTS_OBJECT (surface)->klass;
+  heap_surface_class = heap_surface_class_new (original_class);
+  GTS_OBJECT (surface)->klass = heap_surface_class;
+
+  heap = gts_eheap_new (cost, cost_data);
+  gts_surface_foreach_face (surface, (GtsFunc) make_face_heap, heap);
+  encroached = gts_fifo_new ();
+  
+  GTS_OBJECT (surface)->reserved = heap;
+
+  while (steiner_max-- != 0 && (f = gts_eheap_remove_top (heap, NULL))) {
+    GtsVertex * c = 
+      GTS_VERTEX (gts_triangle_circumcircle_center (GTS_TRIANGLE (f),
+		  GTS_POINT_CLASS (surface->vertex_class)));
+    EHEAP_PAIR (f) = NULL;
+    g_assert (c != NULL);
+    g_assert (gts_delaunay_add_vertex (surface, c, f) == NULL);
+
+    vertex_encroaches (c, surface, encroached, encroaches, encroach_data);
+    if (!gts_fifo_is_empty (encroached)) {
+      gts_delaunay_remove_vertex (surface, c);
+      steiner_max = split_encroached (surface, 
+				      encroached, 
+				      steiner_max, 
+				      encroaches, 
+				      encroach_data);
+    }
+  }
+
+  unrefined_number = gts_eheap_size (heap);
+  gts_eheap_foreach (heap, (GFunc) gts_object_reset_reserved, NULL);
+  gts_eheap_destroy (heap);
+
+  gts_fifo_foreach (encroached, (GtsFunc) gts_object_reset_reserved, NULL);
+  gts_fifo_destroy (encroached);
+
+  GTS_OBJECT (surface)->klass = original_class;
+  GTS_OBJECT (surface)->reserved = NULL;
+  g_free (heap_surface_class);
+
+  return unrefined_number;
+}
diff --git a/gts/rounding.h b/gts/rounding.h
new file mode 100644
index 0000000..053b32f
--- /dev/null
+++ b/gts/rounding.h
@@ -0,0 +1,85 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "config.h"
+
+#ifdef HAVE_FPU_CONTROL_H
+#  include <fpu_control.h>
+#  ifdef _FPU_EXTENDED
+#   if !defined(__alpha__) || !defined(__GLIBC__)
+#    if defined(__arm__)
+     static fpu_control_t fpu_round_double = _FPU_DEFAULT;
+#    else
+     static fpu_control_t fpu_round_double =
+       (_FPU_DEFAULT & ~ _FPU_EXTENDED)|_FPU_DOUBLE;
+#    endif
+     static fpu_control_t fpu_init;
+#    define FPU_ROUND_DOUBLE  { _FPU_GETCW(fpu_init);\
+                                _FPU_SETCW(fpu_round_double); }
+#    define FPU_RESTORE       {_FPU_SETCW(fpu_init);}
+#   else /* __alpha__ && __GLIBC__ */
+#    define FPU_ROUND_DOUBLE
+#    define FPU_RESTORE
+#   endif /* __alpha__ && __GLIBC__ */
+#  else /* not FPU_EXTENDED */
+#    define FPU_ROUND_DOUBLE
+#    define FPU_RESTORE
+#  endif /* not FPU_EXTENDED */
+#else /* not HAVE_FPU_CONTROL_H */
+#  ifdef __FreeBSD__
+#    include <floatingpoint.h>
+#    define FPU_ROUND_DOUBLE  (fpsetprec(FP_PD))
+#    define FPU_RESTORE       (fpsetprec(FP_PE))
+#  else /* not __FreeBSD__ */
+#    ifdef WIN32
+#      ifdef _MSC_VER
+#        include <float.h>
+         static unsigned int fpu_init;
+#        define FPU_ROUND_DOUBLE (fpu_init = _controlfp (0, 0),\
+                                 _controlfp (_PC_53, MCW_PC))
+#        define FPU_RESTORE      (_controlfp (fpu_init, 0xfffff))
+#      elif __MINGW32__
+#        include <float.h>
+         static unsigned int fpu_init;
+#        define FPU_ROUND_DOUBLE (fpu_init = _controlfp (0, 0),\
+                                  _controlfp (_PC_53, _MCW_PC))
+#        define FPU_RESTORE      (_controlfp (fpu_init, 0xfffff))
+#      else /* not _MSC_VER or __MINGW32__ */
+#        error "You need MSVC or MinGW for the Win32 version"
+#      endif /*  not _MSC_VER or __MINGW32__ */
+#    else /* not WIN32 */
+#      ifdef __CYGWIN__
+         typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__HI__)));
+         static fpu_control_t fpu_round_double = 0x027f;
+         static fpu_control_t fpu_init;
+#        define _FPU_GETCW(cw) __asm__ ("fnstcw %0" : "=m" (*&cw))
+#        define _FPU_SETCW(cw) __asm__ ("fldcw %0" : : "m" (*&cw))
+#        define FPU_ROUND_DOUBLE  { _FPU_GETCW(fpu_init);\
+                                    _FPU_SETCW(fpu_round_double); }
+#        define FPU_RESTORE       { _FPU_SETCW(fpu_init);}
+#      else /* not __CYGWIN__ */
+#        ifdef CPP_HAS_WARNING
+#          warning "Unknown CPU: assuming default double precision rounding"
+#        endif /* CPP_HAS_WARNING */
+#        define FPU_ROUND_DOUBLE
+#        define FPU_RESTORE
+#      endif /* not __CYGWIN__ */
+#    endif /* not WIN32 */
+#  endif /* not __FreeBSD__ */
+#endif /* not HAVE_FPU_CONTROL_H */
diff --git a/gts/segment.c b/gts/segment.c
new file mode 100644
index 0000000..58a0540
--- /dev/null
+++ b/gts/segment.c
@@ -0,0 +1,233 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "gts.h"
+
+static void segment_destroy (GtsObject * object)
+{
+  GtsSegment * segment = GTS_SEGMENT (object);
+  GtsVertex * v1 = segment->v1;
+  GtsVertex * v2 = segment->v2;
+
+  v1->segments = g_slist_remove (v1->segments, segment);
+  if (!GTS_OBJECT_DESTROYED (v1) &&
+      !gts_allow_floating_vertices && v1->segments == NULL)
+    gts_object_destroy (GTS_OBJECT (v1));
+
+  v2->segments = g_slist_remove (v2->segments, segment);
+  if (!GTS_OBJECT_DESTROYED (v2) &&
+      !gts_allow_floating_vertices && v2->segments == NULL)
+    gts_object_destroy (GTS_OBJECT (v2));
+
+  (* GTS_OBJECT_CLASS (gts_segment_class ())->parent_class->destroy) (object);
+}
+
+static void segment_class_init (GtsObjectClass * klass)
+{
+  klass->destroy = segment_destroy;
+}
+
+static void segment_init (GtsSegment * segment)
+{
+  segment->v1 = segment->v2 = NULL;
+}
+
+/**
+ * gts_segment_class:
+ *
+ * Returns: the #GtsSegmentClass.
+ */
+GtsSegmentClass * gts_segment_class (void)
+{
+  static GtsSegmentClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo segment_info = {
+      "GtsSegment",
+      sizeof (GtsSegment),
+      sizeof (GtsSegmentClass),
+      (GtsObjectClassInitFunc) segment_class_init,
+      (GtsObjectInitFunc) segment_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (gts_object_class (), 
+				  &segment_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_segment_new:
+ * @klass: a #GtsSegmentClass.
+ * @v1: a #GtsVertex.
+ * @v2: another #GtsVertex different from @v1.
+ *
+ * Returns: a new #GtsSegment linking @v1 and @v2.
+ */
+GtsSegment * gts_segment_new (GtsSegmentClass * klass, 
+			      GtsVertex * v1, GtsVertex * v2)
+{
+  GtsSegment * s;
+
+  g_return_val_if_fail (v1 != NULL, NULL);
+  g_return_val_if_fail (v2 != NULL, NULL);
+  g_return_val_if_fail (v1 != v2, NULL);
+
+  s = GTS_SEGMENT (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  s->v1 = v1;
+  s->v2 = v2;
+  v1->segments = g_slist_prepend (v1->segments, s);
+  v2->segments = g_slist_prepend (v2->segments, s);
+  
+  return s;
+}
+
+/**
+ * gts_segment_is_duplicate:
+ * @s: a #GtsSegment.
+ *
+ * Returns: the first #GtsSegment different from @s which shares the
+ * same endpoints or %NULL if there is none.
+ */
+GtsSegment * gts_segment_is_duplicate (GtsSegment * s)
+{
+  GSList * i;
+  GtsVertex * v2;
+
+  g_return_val_if_fail (s != NULL, NULL);
+
+  v2 = s->v2;
+  i = s->v1->segments;
+  if (s->v1 == v2) /* s is degenerate: special treatment */
+    while (i) {
+      GtsSegment * s1 = i->data;
+      if (s1 != s && s1->v1 == v2 && s1->v2 == v2)
+	return s1;
+      i = i->next;
+    }
+  else /* s is not degenerate */
+    while (i) {
+      GtsSegment * s1 = i->data;
+      if (s1 != s && (s1->v1 == v2 || s1->v2 == v2))
+	return s1;
+      i = i->next;
+    }
+  return NULL;
+}
+
+/**
+ * gts_segments_are_intersecting:
+ * @s1: a #GtsSegment.
+ * @s2: a #GtsSegment.
+ *
+ * Returns: %GTS_IN if @s1 and @s2 are intersecting, %GTS_ON if one of the
+ * endpoints of @s1 (resp. @s2) lies on @s2 (resp. @s1), %GTS_OUT otherwise.
+ */
+GtsIntersect gts_segments_are_intersecting (GtsSegment * s1, GtsSegment * s2)
+{
+  GtsPoint * p1, * p2, * p3, * p4;
+  gdouble d1, d2, d3, d4;
+
+  g_return_val_if_fail (s1 != NULL && s2 != NULL, FALSE);
+
+  p1 = GTS_POINT (s1->v1); p2 = GTS_POINT (s1->v2);
+  p3 = GTS_POINT (s2->v1); p4 = GTS_POINT (s2->v2);
+  d1 = gts_point_orientation (p1, p2, p3);
+  d2 = gts_point_orientation (p1, p2, p4);
+  if ((d1 > 0.0 && d2 > 0.0) ||
+      (d1 < 0.0 && d2 < 0.0))
+    return GTS_OUT;
+  d3 = gts_point_orientation (p3, p4, p1);
+  d4 = gts_point_orientation (p3, p4, p2);
+  if ((d3 > 0.0 && d4 > 0.0) ||
+      (d3 < 0.0 && d4 < 0.0))
+    return GTS_OUT;
+  if (d1 == 0.0 || d2 == 0.0 || d3 == 0.0 || d4 == 0.0)
+    return GTS_ON;
+  return GTS_IN;
+}
+
+/**
+ * gts_segment_midvertex:
+ * @s: a #GtsSegment.
+ * @klass: a #GtsVertexClass to be used for the new vertex.
+ *
+ * Returns: a new #GtsVertex, midvertex of @s.
+ */
+GtsVertex * gts_segment_midvertex (GtsSegment * s, GtsVertexClass * klass)
+{
+  GtsPoint * p1, * p2;
+
+  g_return_val_if_fail (s != NULL, NULL);
+  g_return_val_if_fail (klass != NULL, NULL);
+
+  p1 = GTS_POINT (s->v1); p2 = GTS_POINT (s->v2);
+  return gts_vertex_new (klass,
+			 (p1->x + p2->x)/2., 
+			 (p1->y + p2->y)/2.,
+			 (p1->z + p2->z)/2.);
+}
+
+/**
+ * gts_segments_from_vertices:
+ * @vertices: a list of #GtsVertex.
+ * 
+ * Returns: a list of unique #GtsSegment which have one of their vertices in 
+ * @vertices.
+ */
+GSList * gts_segments_from_vertices (GSList * vertices)
+{
+  GHashTable * hash;
+  GSList * segments = NULL, * i;
+
+  hash = g_hash_table_new (NULL, NULL);
+  i = vertices;
+  while (i) {
+    GSList * j = GTS_VERTEX (i->data)->segments;
+    while (j) {
+      GtsSegment * s = j->data;
+      if (g_hash_table_lookup (hash, s) == NULL) {
+	segments = g_slist_prepend (segments, s);
+	g_hash_table_insert (hash, s, i);
+      }
+      j = j->next;
+    }
+    i = i->next;
+  }
+  g_hash_table_destroy (hash);
+  return segments;
+}
+
+/**
+ * gts_segment_is_ok:
+ * @s: a #GtsSegment.
+ * 
+ * Returns: %TRUE if @s is not degenerate (i.e. @s->v1 != @s->v2) and not 
+ * duplicate, %FALSE otherwise.
+ */
+gboolean gts_segment_is_ok (GtsSegment * s)
+{
+  g_return_val_if_fail (s != NULL, FALSE);
+  g_return_val_if_fail (s->v1 != s->v2, FALSE);
+  g_return_val_if_fail (!gts_segment_is_duplicate (s), FALSE);
+  g_return_val_if_fail (GTS_OBJECT (s)->reserved == NULL, FALSE);
+  return TRUE;
+}
diff --git a/gts/split.c b/gts/split.c
new file mode 100644
index 0000000..8283e17
--- /dev/null
+++ b/gts/split.c
@@ -0,0 +1,1840 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include "gts.h"
+
+#define DYNAMIC_SPLIT
+#define NEW
+
+/* #define DEBUG
+   #define DEBUG_HEXPAND
+   #define DEBUG_EXPAND */
+
+struct _GtsSplitCFace {
+  GtsFace * f;
+  GtsTriangle ** a1, ** a2;
+};
+
+typedef struct _CFace      CFace;
+typedef struct _CFaceClass CFaceClass;
+
+struct _CFace {
+  GtsObject object; 
+
+  GtsSplit * parent_split;
+  GtsTriangle * t;
+  guint flags;
+};
+/* the size of the CFace structure must be smaller or equal to the size
+   of the GtsFace structure as both structures use the same memory location */
+
+struct _CFaceClass {
+  GtsObjectClass parent_class;
+};
+
+#define IS_CFACE(obj) (gts_object_is_from_class (obj, cface_class ()))
+#define CFACE(obj)    ((CFace *) obj)
+#define CFACE_ORIENTATION(cf) ((cf)->flags & 0x1)
+#define CFACE_ORIENTATION_DIRECT(cf) ((cf)->flags |= 0x1)
+#define CFACE_VVS(cf)                ((cf)->flags & 0x2)
+#define CFACE_VVS_DIRECT(cf)         ((cf)->flags |= 0x2)
+#define CFACE_E1                     0x4
+#define CFACE_E2                     0x8
+#define CFACE_KEEP_VVS               0x10
+
+#define ROTATE_ORIENT(e, e1, e2, e3)  { if (e1 == e) { e1 = e2; e2 = e3; }\
+                                 else if (e2 == e) { e2 = e1; e1 = e3; }\
+                                 else g_assert (e3 == e); }
+#define SEGMENT_USE_VERTEX(s, v) ((s)->v1 == v || (s)->v2 == v)
+#define TRIANGLE_REPLACE_EDGE(t, e, with) { if ((t)->e1 == e)\
+					      (t)->e1 = with;\
+					    else if ((t)->e2 == e)\
+					      (t)->e2 = with;\
+					    else {\
+					      g_assert ((t)->e3 == e);\
+					      (t)->e3 = with;\
+					    }\
+                                          }
+
+#define HEAP_INSERT_OBJECT(h, e) (GTS_OBJECT (e)->reserved =\
+				  gts_eheap_insert (h, e))
+#define HEAP_REMOVE_OBJECT(h, e) (gts_eheap_remove (h, GTS_OBJECT (e)->reserved),\
+				   GTS_OBJECT (e)->reserved = NULL)
+
+static GtsObjectClass * cface_class (void)
+{
+  static GtsObjectClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo cface_info = {
+      "GtsCFace",
+      sizeof (CFace),
+      sizeof (CFaceClass),
+      (GtsObjectClassInitFunc) NULL,
+      (GtsObjectInitFunc) NULL,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (gts_object_class (), &cface_info);
+    g_assert (sizeof (CFace) <= sizeof (GtsFace));
+  }
+
+  return klass;
+}
+
+/* Replace @e with @with for all the triangles using @e but @f.
+   Destroys @e and removes it from @heap (if not %NULL). 
+   Returns a triangle using e different from f or %NULL. */
+static GtsTriangle * replace_edge_collapse (GtsEdge * e, 
+					    GtsEdge * with, 
+					    CFace * cf,
+					    GtsEHeap * heap
+#ifdef DYNAMIC_SPLIT
+					    , GtsTriangle *** a1
+#endif
+#ifdef NEW
+					    , guint edge_flag
+#endif
+					    )
+{
+  GSList * i;
+  GtsTriangle * rt = NULL;
+#ifdef DYNAMIC_SPLIT
+  guint size;
+  GtsTriangle ** a;
+#endif
+
+#ifdef NEW
+  i = e->triangles;
+  e->triangles = NULL;
+  size = g_slist_length (i)*sizeof (GtsTriangle *);
+  *a1 = a = g_malloc (size > 0 ? size : sizeof (GtsTriangle *));
+  while (i) {
+    GtsTriangle * t = i->data;
+    GSList * next = i->next;
+    if (t != ((GtsTriangle *) cf)) {
+      if (IS_CFACE (t)) {
+	i->next = e->triangles;
+	e->triangles = i;
+	/* set the edge given by edge_flag (CFACE_E1 or CFACE_E2) */
+	GTS_OBJECT (t)->reserved = GUINT_TO_POINTER (edge_flag);
+	cf->flags |= CFACE_KEEP_VVS;
+      }
+      else {
+	TRIANGLE_REPLACE_EDGE (t, e, with);
+	i->next = with->triangles;
+	with->triangles = i;
+	rt = t;
+	*(a++) = t;
+      }
+    }
+    else
+      g_slist_free_1 (i);
+    i = next;
+  }
+  *a = NULL;
+  if (!e->triangles) {
+    if (heap)
+      HEAP_REMOVE_OBJECT (heap, e);
+    gts_object_destroy (GTS_OBJECT (e));
+  }
+#else /* not NEW */
+  i = e->triangles;
+#ifdef DYNAMIC_SPLIT
+  size = g_slist_length (i)*sizeof (GtsTriangle *);
+  *a1 = a = g_malloc (size > 0 ? size : sizeof (GtsTriangle *));
+#endif
+  while (i) {
+    GtsTriangle * t = i->data;
+    GSList * next = i->next;
+    if (t != ((GtsTriangle *) cf)) {
+      TRIANGLE_REPLACE_EDGE (t, e, with);
+      i->next = with->triangles;
+      with->triangles = i;
+      rt = t;
+#ifdef DYNAMIC_SPLIT
+      *(a++) = t;
+#endif
+    }
+    else
+      g_slist_free_1 (i);
+    i = next;
+  }
+#ifdef DYNAMIC_SPLIT
+  *a = NULL;
+#endif
+  if (heap)
+    HEAP_REMOVE_OBJECT (heap, e);
+  e->triangles = NULL;
+  gts_object_destroy (GTS_OBJECT (e));
+#endif /* NEW */
+
+  return rt;
+}
+
+static CFace * cface_new (GtsFace * f,
+			  GtsEdge * e,
+			  GtsVertex * v1, 
+			  GtsVertex * v2,
+			  GtsSplit * vs,
+			  GtsEHeap * heap,
+			  GtsEdgeClass * klass
+#ifdef DYNAMIC_SPLIT
+			  , GtsSplitCFace * scf
+#endif
+			  )
+{
+  CFace * cf;
+  GtsVertex * v;
+  GtsEdge * e1, * e2, * e3, * vvs;
+  GSList * i;
+  GtsTriangle * t, * t1 = NULL, * t2 = NULL;
+  guint flags;
+
+  g_return_val_if_fail (f != NULL, NULL);
+#ifndef NEW
+  g_return_val_if_fail (GTS_IS_FACE (f), NULL);
+#endif
+  g_return_val_if_fail (e != NULL, NULL);
+  g_return_val_if_fail (vs != NULL, NULL);
+
+  t = ((GtsTriangle *) f);
+  if (heap)
+    g_return_val_if_fail (!gts_triangle_is_duplicate (t), NULL);
+
+#ifdef NEW
+  /* get CFACE_E1 and CFACE_E2 info */
+  flags = GPOINTER_TO_UINT (GTS_OBJECT (f)->reserved);
+#endif
+  GTS_OBJECT_SET_FLAGS (f, GTS_DESTROYED);
+
+  i = f->surfaces;
+  while (i) {
+    GSList * next = i->next;
+    gts_surface_remove_face (i->data, f);
+    i = next;
+  }
+  g_slist_free (f->surfaces);
+
+  e1 = t->e1; e2 = t->e2; e3 = t->e3;
+  ROTATE_ORIENT (e, e1, e2, e3);
+
+  cf = (CFace *) f;
+#ifndef NEW
+  GTS_OBJECT (cf)->klass = cface_class ();
+#else
+  cf->flags = flags;
+#endif
+  gts_object_init (GTS_OBJECT (cf), cface_class ());
+  cf->parent_split = vs;
+
+  if (SEGMENT_USE_VERTEX (GTS_SEGMENT (e1), v2)) {
+    CFACE_ORIENTATION_DIRECT (cf); /* v1->v2->v */
+    e3 = e1; e1 = e2; e2 = e3;
+  }
+  v = GTS_SEGMENT (e1)->v1 == v1 ?
+    GTS_SEGMENT (e1)->v2 : GTS_SEGMENT (e1)->v1;
+#ifdef NEW
+  if ((cf->flags & CFACE_E1) || (cf->flags & CFACE_E2))
+    g_assert ((vvs = GTS_EDGE (gts_vertices_are_connected (vs->v, v))));
+  else
+#endif
+  vvs = gts_edge_new (klass, v, vs->v);
+
+  t1 = replace_edge_collapse (e1, vvs, cf, heap
+#ifdef DYNAMIC_SPLIT
+			      , &scf->a1
+#endif
+#ifdef NEW
+			      , CFACE_E1
+#endif
+			      );
+  t2 = replace_edge_collapse (e2, vvs, cf, heap
+#ifdef DYNAMIC_SPLIT
+			      , &scf->a2
+#endif
+#ifdef NEW
+			      , CFACE_E2
+#endif
+			      );
+  t = cf->t = t1 ? t1 : t2;
+  g_assert (t);
+
+  /* set up flags necessary to find vvs */
+  if (t->e1 == vvs) e2 = t->e2;
+  else if (t->e2 == vvs) e2 = t->e3;
+  else {
+    g_assert (t->e3 == vvs);
+    e2 = t->e1;
+  }
+  if (SEGMENT_USE_VERTEX (GTS_SEGMENT (e2), v))
+    CFACE_VVS_DIRECT (cf);
+
+  return cf;
+}
+
+static void find_vvs (GtsVertex * vs,
+		      GtsTriangle * t,
+		      GtsVertex ** v, GtsEdge ** vvs,
+		      gboolean orientation)
+{
+  GtsEdge * e1 = t->e1, * e2 = t->e2, * e3 = t->e3, * tmp;
+
+  if (SEGMENT_USE_VERTEX (GTS_SEGMENT (e2), vs)) {
+    tmp = e1; e1 = e2; e2 = e3; e3 = tmp;
+  }
+  else if (SEGMENT_USE_VERTEX (GTS_SEGMENT (e3), vs)) {
+    tmp = e1; e1 = e3; e3 = e2; e2 = tmp;
+  }
+  else
+    g_assert (SEGMENT_USE_VERTEX (GTS_SEGMENT (e1), vs));
+  if (SEGMENT_USE_VERTEX (GTS_SEGMENT (e2), vs) ||
+      !gts_segments_touch (GTS_SEGMENT (e1), GTS_SEGMENT (e2))) {
+    tmp = e1; e1 = e2; e2 = e3; e3 = tmp;
+    g_assert (gts_segments_touch (GTS_SEGMENT (e1), GTS_SEGMENT (e2)));
+  }
+
+  *vvs = orientation ? e1 : e3;
+
+  if (GTS_SEGMENT (*vvs)->v1 != vs) {
+    g_assert (GTS_SEGMENT (*vvs)->v2 == vs);
+    *v = GTS_SEGMENT (*vvs)->v1;
+  }
+  else
+    *v = GTS_SEGMENT (*vvs)->v2;
+}
+
+static void replace_edge_expand (GtsEdge * e, 
+				 GtsEdge * with,
+				 GtsTriangle ** a,
+				 GtsVertex * v)
+{
+  GtsTriangle ** i = a, * t;
+
+  while ((t = *(i++))) {
+#ifdef DEBUG_EXPAND
+    g_assert (!IS_CFACE (t));
+    fprintf (stderr, "replacing %p->%d: e: %p->%d with: %p->%d\n",
+	     t, id (t), e, id (e), with, id (with));
+#endif
+    TRIANGLE_REPLACE_EDGE (t, e, with);
+    with->triangles = g_slist_prepend (with->triangles, t);
+    if (GTS_OBJECT (t)->reserved) {
+      /* apart from the triangles having e as an edge, t is the only
+	 triangle using v */
+      g_assert (GTS_OBJECT (t)->reserved == v);
+      GTS_OBJECT (t)->reserved = NULL;
+    }
+    else
+      GTS_OBJECT (t)->reserved = v;
+  }
+}
+
+static void cface_expand (CFace * cf,
+			  GtsTriangle ** a1,
+			  GtsTriangle ** a2,
+			  GtsEdge * e,
+			  GtsVertex * v1, 
+			  GtsVertex * v2,
+			  GtsVertex * vs,
+			  GtsEdgeClass * klass)
+{
+  GtsVertex * v;
+  GtsEdge * e1, * e2, * vvs;
+  gboolean orientation;
+  guint flags;
+
+  g_return_if_fail (cf != NULL);
+  g_return_if_fail (IS_CFACE (cf));
+  g_return_if_fail (e != NULL);
+  g_return_if_fail (vs != NULL);
+
+  flags = cf->flags;
+  orientation = CFACE_ORIENTATION (cf);
+
+  find_vvs (vs, cf->t, &v, &vvs, CFACE_VVS (cf));
+
+#ifdef NEW
+  if (flags & CFACE_E1)
+    e1 = GTS_EDGE (gts_vertices_are_connected (v1, v));
+  else
+    e1 = gts_edge_new (klass, v, v1);
+  if (flags & CFACE_E2)
+    e2 = GTS_EDGE (gts_vertices_are_connected (v2, v));
+  else
+    e2 = gts_edge_new (klass, v, v2);
+#else
+  e1 = gts_edge_new (v, v1);
+  e2 = gts_edge_new (v, v2);
+#endif
+
+  replace_edge_expand (vvs, e1, a1, v1);
+  replace_edge_expand (vvs, e2, a2, v2);
+
+#ifdef NEW
+  if (!(flags & CFACE_KEEP_VVS)) {
+    g_slist_free (vvs->triangles);
+    vvs->triangles = NULL;
+    gts_object_destroy (GTS_OBJECT (vvs));
+  }
+#else
+  g_slist_free (vvs->triangles);
+  vvs->triangles = NULL;
+  gts_object_destroy (GTS_OBJECT (vvs));
+#endif
+
+  /* gts_face_new : because I am "creating" a face */
+  GTS_OBJECT (cf)->klass = GTS_OBJECT_CLASS (gts_face_class ());
+  gts_object_init (GTS_OBJECT (cf), GTS_OBJECT (cf)->klass);
+  
+  if (orientation)
+    gts_triangle_set (GTS_TRIANGLE (cf), e, e2, e1);
+  else
+    gts_triangle_set (GTS_TRIANGLE (cf), e, e1, e2);
+}
+
+static void split_destroy (GtsObject * object)
+{
+  GtsSplit * vs = GTS_SPLIT (object);
+  guint i = vs->ncf;
+  GtsSplitCFace * cf = vs->cfaces;
+
+  while (i--) {
+    if (IS_CFACE (cf->f))
+      gts_object_destroy (GTS_OBJECT (cf->f));
+    g_free (cf->a1);
+    g_free (cf->a2);
+    cf++;
+  }
+  g_free (vs->cfaces);
+
+  if (!gts_allow_floating_vertices && vs->v && vs->v->segments == NULL)
+    gts_object_destroy (GTS_OBJECT (vs->v));
+
+  (* GTS_OBJECT_CLASS (gts_split_class ())->parent_class->destroy) (object);
+}
+
+static void split_class_init (GtsObjectClass * klass)
+{
+  klass->destroy = split_destroy;
+}
+
+static void split_init (GtsSplit * split)
+{
+  split->v1 = split->v2 = NULL;
+  split->v = NULL;
+  split->cfaces = NULL;
+  split->ncf = 0;
+}
+
+/**
+ * gts_split_class:
+ *
+ * Returns: the #GtsSplitClass.
+ */
+GtsSplitClass * gts_split_class (void)
+{
+  static GtsSplitClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo split_info = {
+      "GtsSplit",
+      sizeof (GtsSplit),
+      sizeof (GtsSplitClass),
+      (GtsObjectClassInitFunc) split_class_init,
+      (GtsObjectInitFunc) split_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (gts_object_class (), 
+				  &split_info);
+  }
+
+  return klass;
+}
+
+#ifdef DEBUG
+static gboolean edge_collapse_is_valid (GtsEdge * e)
+{
+  GSList * i;
+
+  g_return_val_if_fail (e != NULL, FALSE);
+  
+  if (gts_segment_is_duplicate (GTS_SEGMENT (e))) {
+    g_warning ("collapsing duplicate edge");
+    return FALSE;
+  }
+    
+  i = GTS_SEGMENT (e)->v1->segments;
+  while (i) {
+    GtsEdge * e1 = i->data;
+    if (e1 != e && GTS_IS_EDGE (e1)) {
+      GtsEdge * e2 = NULL;
+      GSList * j = GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e)->v1 ? 
+	GTS_SEGMENT (e1)->v2->segments : GTS_SEGMENT (e1)->v1->segments;
+      while (j && !e2) {
+	GtsEdge * e1 = j->data;
+	if (GTS_IS_EDGE (e1) && 
+	    (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e)->v2 || 
+	     GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e)->v2))
+	  e2 = e1;
+	j = j->next;
+      }
+      if (e2 && !gts_triangle_use_edges (e, e1, e2)) {
+	g_warning ("collapsing empty triangle");
+	return FALSE;
+      }
+    }
+    i = i->next;
+  }
+
+  if (gts_edge_is_boundary (e, NULL)) {
+    GtsTriangle * t = e->triangles->data;
+    if (gts_edge_is_boundary (t->e1, NULL) &&
+	gts_edge_is_boundary (t->e2, NULL) &&
+	gts_edge_is_boundary (t->e3, NULL)) {
+      g_warning ("collapsing single triangle");
+      return FALSE;
+    }
+  }
+  else {
+    if (gts_vertex_is_boundary (GTS_SEGMENT (e)->v1, NULL) &&
+	gts_vertex_is_boundary (GTS_SEGMENT (e)->v2, NULL)) {
+      g_warning ("collapsing two sides of a strip");
+      return FALSE;    
+    }
+    if (gts_edge_belongs_to_tetrahedron (e)) {
+      g_warning ("collapsing tetrahedron");
+      return FALSE;
+    }
+  }
+
+  return TRUE;
+}
+#endif /* DEBUG */
+
+/* Not currently used.  May be useful for some debug code */
+#ifdef DEBUG
+static void print_split (GtsSplit * vs, FILE * fptr)
+{
+  guint j;
+  GtsSplitCFace * cf;
+
+  g_return_if_fail (vs != NULL);
+  g_return_if_fail (fptr != NULL);
+
+  fprintf (fptr, "%p: v: %p v1: %p v2: %p ncf: %u cfaces: %p\n",
+	   vs, vs->v, vs->v1, vs->v2, vs->ncf, vs->cfaces);
+  cf = vs->cfaces;
+  j = vs->ncf;
+  while (j--) {
+    fprintf (stderr, "  f: %p a1: %p a2: %p\n",
+	     cf->f, cf->a1, cf->a2);
+    cf++;
+  }
+}
+#endif
+
+/**
+ * gts_split_collapse:
+ * @vs: a #GtsSplit.
+ * @klass: a #GtsEdgeClass.
+ * @heap: a #GtsEHeap or %NULL.
+ *
+ * Collapses the vertex split @vs. Any new edge created during the process will
+ * be of class @klass. If heap is not %NULL, the new edges will be inserted
+ * into it and the destroyed edges will be removed from it.
+ */
+void gts_split_collapse (GtsSplit * vs, 
+			 GtsEdgeClass * klass,
+			 GtsEHeap * heap)
+{
+  GtsEdge * e;
+  GtsVertex * v, * v1, * v2;
+  GSList * i, * end;
+#ifdef DYNAMIC_SPLIT
+  GtsSplitCFace * cf;
+  guint j;
+#endif
+#ifdef DEBUG
+  gboolean invalid = FALSE;
+  static guint ninvalid = 0;
+#endif
+
+  g_return_if_fail (vs != NULL);
+  g_return_if_fail (klass != NULL);
+
+  v = vs->v;
+
+  g_return_if_fail (v->segments == NULL);
+  
+  /* we don't want to destroy vertices */
+  gts_allow_floating_vertices = TRUE;
+
+  v1 = GTS_SPLIT_V1 (vs);
+  v2 = GTS_SPLIT_V2 (vs);
+  g_assert ((e = GTS_EDGE (gts_vertices_are_connected (v1, v2))));
+
+#ifdef DEBUG
+  fprintf (stderr, "collapsing %p: v1: %p v2: %p v: %p\n", vs, v1, v2, v);
+  if (!edge_collapse_is_valid (e)) {
+    char fname[80];
+    FILE * fptr;
+    GSList * triangles, * i;
+
+    g_warning ("invalid edge collapse");
+    invalid = TRUE;
+    sprintf (fname, "invalid.%d", ninvalid);
+    fptr = fopen (fname, "wt");
+    gts_write_segment (GTS_SEGMENT (e), GTS_POINT (v), fptr);
+    triangles = gts_vertex_triangles (v1, NULL);
+    triangles = gts_vertex_triangles (v2, triangles);
+    i = triangles;
+    while (i) {
+      gts_write_triangle (i->data, GTS_POINT (v), fptr);
+      i = i->next;
+    }
+    g_slist_free (triangles);
+    fclose (fptr);
+  }
+#endif
+
+  i = e->triangles;
+#ifdef DYNAMIC_SPLIT
+  cf = vs->cfaces;
+  j = vs->ncf;
+  while (j--) {
+    g_free (cf->a1);
+    g_free (cf->a2);
+    cf++;
+  }
+  g_free (vs->cfaces);
+
+  vs->ncf = g_slist_length (i);
+  g_assert (vs->ncf > 0);
+  cf = vs->cfaces = g_malloc (vs->ncf*sizeof (GtsSplitCFace));
+#endif /* DYNAMIC_SPLIT */
+#ifdef NEW
+  while (i) {
+    cf->f = i->data;
+    g_assert (GTS_IS_FACE (cf->f));
+    GTS_OBJECT (cf->f)->klass = GTS_OBJECT_CLASS (cface_class ());
+    cf++;
+    i = i->next;
+  }
+  i = e->triangles;
+  cf = vs->cfaces;
+  while (i) {
+    cface_new (i->data, e, v1, v2, vs, heap, klass, cf);
+#ifdef DEBUG
+    fprintf (stderr, "cface: %p->%d t: %p->%d a1: ", 
+	     cf->f, id (cf->f), CFACE (cf->f)->t, id (CFACE (cf->f)->t));
+    {
+      GtsTriangle * t, ** a;
+      a = cf->a1;
+      while ((t = *(a++)))
+	fprintf (stderr, "%p->%d ", t, id (t));
+      fprintf (stderr, "a2: ");
+      a = cf->a2;
+      while ((t = *(a++)))
+	fprintf (stderr, "%p->%d ", t, id (t));
+      fprintf (stderr, "\n");
+    }
+#endif
+    cf++;
+    i = i->next;
+  }
+#else /* not NEW */
+  while (i) {
+    cface_new (i->data, e, v1, v2, vs, heap
+#ifdef DYNAMIC_SPLIT
+	       , cf
+#endif /* DYNAMIC_SPLIT */
+	       );
+#ifdef DYNAMIC_SPLIT
+    cf->f = i->data;
+    cf++;
+#endif /* DYNAMIC_SPLIT */
+    i = i->next;
+  }
+#endif /* NEW */
+  g_slist_free (e->triangles);
+  e->triangles = NULL;
+  gts_object_destroy (GTS_OBJECT (e));
+
+  gts_allow_floating_vertices = FALSE;
+
+  end = NULL;
+  i = v1->segments;
+  while (i) {
+    GtsSegment * s = i->data;
+    if (s->v1 == v1)
+      s->v1 = v;
+    else
+      s->v2 = v;
+    end = i;
+    i = i->next;
+  }
+  if (end) {
+    end->next = v->segments;
+    v->segments = v1->segments;
+    v1->segments = NULL;
+  }
+
+  end = NULL;
+  i = v2->segments;
+  while (i) {
+    GtsSegment * s = i->data;
+    if (s->v1 == v2)
+      s->v1 = v;
+    else
+      s->v2 = v;
+    end = i;
+    i = i->next;
+  }
+  if (end) {
+    end->next = v->segments;
+    v->segments = v2->segments;
+    v2->segments = NULL;
+  }
+
+#ifdef DEBUG
+  if (invalid) {
+    char fname[80];
+    FILE * fptr;
+    GSList * triangles, * i;
+    GtsSurface * surface = NULL;
+
+    sprintf (fname, "invalid_after.%d", ninvalid);
+    fptr = fopen (fname, "wt");
+    triangles = gts_vertex_triangles (v, NULL);
+    i = triangles;
+    while (i) {
+      GtsTriangle * t = i->data;
+      fprintf (stderr, "checking %p->%d\n", t, id (t));
+      g_assert (GTS_IS_FACE (t));
+      gts_write_triangle (t, GTS_POINT (v), fptr);
+      surface = GTS_FACE (t)->surfaces->data;
+      if (gts_triangle_is_duplicate (t))
+	fprintf (stderr, "%p->%d is duplicate\n", t, id (t));
+      if (gts_segment_is_duplicate (GTS_SEGMENT (t->e1)))
+	fprintf (stderr, "e1 of %p->%d is duplicate\n", t, id (t));
+      if (gts_segment_is_duplicate (GTS_SEGMENT (t->e2)))
+	fprintf (stderr, "e2 of %p->%d is duplicate\n", t, id (t));
+      if (gts_segment_is_duplicate (GTS_SEGMENT (t->e3)))
+	fprintf (stderr, "e3 of %p->%d is duplicate\n", t, id (t));
+      i = i->next;
+    }
+    fclose (fptr);
+    g_slist_free (triangles);
+#if 0
+    gts_split_expand (vs, surface);
+
+    sprintf (fname, "invalid_after_after.%d", ninvalid);
+    fptr = fopen (fname, "wt");
+    triangles = gts_vertex_triangles (v1, NULL);
+    triangles = gts_vertex_triangles (v2, triangles);
+    i = triangles;
+    while (i) {
+      GtsTriangle * t = i->data;
+      gts_write_triangle (t, GTS_POINT (v), fptr);
+      surface = GTS_FACE (t)->surfaces->data;
+      if (gts_triangle_is_duplicate (t))
+	fprintf (stderr, "%p->%d is duplicate\n", t, id (t));
+      if (gts_segment_is_duplicate (GTS_SEGMENT (t->e1)))
+	fprintf (stderr, "e1 of %p->%d is duplicate\n", t, id (t));
+      if (gts_segment_is_duplicate (GTS_SEGMENT (t->e2)))
+	fprintf (stderr, "e2 of %p->%d is duplicate\n", t, id (t));
+      if (gts_segment_is_duplicate (GTS_SEGMENT (t->e3)))
+	fprintf (stderr, "e3 of %p->%d is duplicate\n", t, id (t));
+      i = i->next;
+    }
+    fclose (fptr);
+    g_slist_free (triangles);
+
+    exit (1);
+#endif
+    ninvalid++;
+  }
+#endif
+}
+
+/**
+ * gts_split_expand:
+ * @vs: a #GtsSplit.
+ * @s: a #GtsSurface.
+ * @klass: a #GtsEdgeClass.
+ *
+ * Expands the vertex split @vs adding the newly created faces to @s. Any 
+ * new edge will be of class @klass.
+ */
+void gts_split_expand (GtsSplit * vs, 
+		       GtsSurface * s,
+		       GtsEdgeClass * klass)
+{
+  GSList * i;
+  GtsEdge * e;
+  GtsVertex * v, * v1, * v2;  
+  gboolean changed = FALSE;
+  GtsSplitCFace * cf;
+  guint j;
+  
+  g_return_if_fail (vs != NULL);
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (klass != NULL);
+
+  /* we don't want to destroy vertices */
+  gts_allow_floating_vertices = TRUE;
+
+  v1 = GTS_SPLIT_V1 (vs);
+  v2 = GTS_SPLIT_V2 (vs);
+  v = vs->v;
+#ifdef DEBUG_EXPAND
+  fprintf (stderr, "expanding %p->%d: v1: %p->%d v2: %p->%d v: %p->%d\n",
+	   vs, id (vs), v1, id (v1), v2, id (v2), v, id (v));
+#endif
+  e = gts_edge_new (klass, v1, v2);
+  cf = vs->cfaces;
+  j = vs->ncf;
+  while (j--) {
+    cface_expand (CFACE (cf->f), cf->a1, cf->a2, e, v1, v2, v, klass);
+    gts_surface_add_face (s, cf->f);
+    cf++;
+  }
+
+  gts_allow_floating_vertices = FALSE;
+
+  /* this part is described by figure "expand.fig" */
+  i = v->segments;
+  while (i) {
+    GtsEdge * e1 = i->data;
+    GtsVertex * with = NULL;
+    GSList * j = e1->triangles, * next = i->next;
+    // fprintf (stderr, "e1: %p->%d\n", e1, id (e1));
+    while (j && !with) {
+      with = GTS_OBJECT (j->data)->reserved;
+      j = j->next;
+    }
+    if (with) {
+      j = e1->triangles;
+      while (j) {
+	GtsTriangle * t = j->data;
+	if (GTS_OBJECT (t)->reserved) {
+	  g_assert (GTS_OBJECT (t)->reserved == with);
+	  GTS_OBJECT (t)->reserved = NULL;
+	}
+	else
+	  GTS_OBJECT (t)->reserved = with;
+	j = j->next;
+      }
+      if (GTS_SEGMENT (e1)->v1 == v)
+	GTS_SEGMENT (e1)->v1 = with;
+      else
+	GTS_SEGMENT (e1)->v2 = with;
+
+      v->segments = g_slist_remove_link (v->segments, i);
+      i->next = with->segments;
+      with->segments = i;
+      changed = TRUE;
+    }
+    if (next)
+      i = next;
+    else {
+      /* check for infinite loop (the crossed out case in 
+	 figure "expand.fig") */
+      g_assert (changed);
+      changed = FALSE;
+      i = v->segments;
+    }
+  }
+}
+
+#ifndef DYNAMIC_SPLIT
+static void cface_neighbors (GtsSplitCFace * cf,
+			     GtsEdge * e,
+			     GtsVertex * v1,
+			     GtsVertex * v2)
+{
+  GtsTriangle * t = GTS_TRIANGLE (cf->f), ** a;
+  GtsEdge * e1 = t->e1, * e2 = t->e2, * e3 = t->e3;
+  GSList * i;
+  guint size;
+
+  ROTATE_ORIENT (e, e1, e2, e3);
+  if (SEGMENT_USE_VERTEX (GTS_SEGMENT (e1), v2)) {
+    e3 = e1; e1 = e2; e2 = e3;
+  }
+  
+  i = e1->triangles;
+  size = g_slist_length (i)*sizeof (GtsTriangle *);
+  a = cf->a1 = g_malloc (size > 0 ? size : sizeof (GtsTriangle *));
+  while (i) {
+    if (i->data != t)
+      *(a++) = i->data;
+    i = i->next;
+  }
+  *a = NULL;
+
+  i = e2->triangles;
+  size = g_slist_length (i)*sizeof (GtsTriangle *);
+  a = cf->a2 = g_malloc (size > 0 ? size : sizeof (GtsTriangle *));
+  while (i) {
+    if (i->data != t)
+      *(a++) = i->data;
+    i = i->next;
+  }
+  *a = NULL;
+}
+#endif /*ifndef DYNAMIC_SPLIT */
+
+/**
+ * gts_split_new:
+ * @klass: a #GtsSplitClass.
+ * @v: a #GtsVertex.
+ * @o1: either a #GtsVertex or a #GtsSplit.
+ * @o2: either a #GtsVertex or a #GtsSplit.
+ *
+ * Creates a new #GtsSplit which would collapse @o1 and @o2 into @v. The 
+ * collapse itself is not performed.
+ *
+ * Returns: the new #GtsSplit.
+ */
+GtsSplit * gts_split_new (GtsSplitClass * klass,
+			  GtsVertex * v,
+			  GtsObject * o1,
+			  GtsObject * o2)
+{
+  GtsSplit * vs;
+  GtsVertex * v1, * v2;
+#ifndef DYNAMIC_SPLIT
+  GtsEdge * e;
+  GSList * i;
+  GtsSplitCFace * cf;
+#endif
+
+  g_return_val_if_fail (klass != NULL, NULL);
+  g_return_val_if_fail (v != NULL, NULL);
+  g_return_val_if_fail (GTS_IS_SPLIT (o1) || GTS_IS_VERTEX (o1), NULL);
+  g_return_val_if_fail (GTS_IS_SPLIT (o2) || GTS_IS_VERTEX (o2), NULL);
+
+  vs = GTS_SPLIT (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  vs->v = v;
+  vs->v1 = o1;
+  vs->v2 = o2;
+  v1 = GTS_SPLIT_V1 (vs);
+  v2 = GTS_SPLIT_V2 (vs);
+#ifdef DYNAMIC_SPLIT
+  vs->ncf = 0;
+  vs->cfaces = NULL;
+#else
+  g_assert ((e = GTS_EDGE (gts_vertices_are_connected (v1, v2))));
+  i = e->triangles;
+  vs->ncf = g_slist_length (i);
+  g_assert (vs->ncf > 0);
+  cf = vs->cfaces = g_malloc (vs->ncf*sizeof (GtsSplitCFace));
+  while (i) {
+    cf->f = i->data;
+    cface_neighbors (cf, e, v1, v2);
+    i = i->next;
+    cf++;
+  }
+#endif
+  
+  return vs;
+}
+
+static gboolean 
+split_traverse_pre_order (GtsSplit *           vs,
+			  GtsSplitTraverseFunc func,
+			  gpointer	       data)
+{
+  if (func (vs, data))
+    return TRUE;
+  if (GTS_IS_SPLIT (vs->v1) &&
+      split_traverse_pre_order (GTS_SPLIT (vs->v1), func, data))
+    return TRUE;
+  if (GTS_IS_SPLIT (vs->v2) &&
+      split_traverse_pre_order (GTS_SPLIT (vs->v2), func, data))
+    return TRUE;
+  return FALSE;
+}
+
+static gboolean 
+split_depth_traverse_pre_order (GtsSplit *             vs,
+				guint                  depth,
+				GtsSplitTraverseFunc   func,
+				gpointer	       data)
+{
+  if (func (vs, data))
+      return TRUE;
+    
+  depth--;
+  if (!depth)
+    return FALSE;
+
+  if (GTS_IS_SPLIT (vs->v1) &&
+      split_depth_traverse_pre_order (GTS_SPLIT (vs->v1), depth, func, data))
+    return TRUE;
+  if (GTS_IS_SPLIT (vs->v2) &&
+      split_depth_traverse_pre_order (GTS_SPLIT (vs->v2), depth, func, data))
+    return TRUE;
+  return FALSE;
+}
+
+static gboolean 
+split_traverse_post_order (GtsSplit *           vs,
+			   GtsSplitTraverseFunc func,
+			   gpointer	        data)
+{
+  if (GTS_IS_SPLIT (vs->v1) &&
+      split_traverse_post_order (GTS_SPLIT (vs->v1), func, data))
+    return TRUE;
+  if (GTS_IS_SPLIT (vs->v2) &&
+      split_traverse_post_order (GTS_SPLIT (vs->v2), func, data))
+    return TRUE;
+  if (func (vs, data))
+    return TRUE;
+  return FALSE;
+}
+
+static gboolean
+split_depth_traverse_post_order (GtsSplit *           vs,
+				 guint                depth,
+				 GtsSplitTraverseFunc func,
+				 gpointer	      data)
+{
+  depth--;
+  if (depth) {
+    if (GTS_IS_SPLIT (vs->v1) &&
+	split_depth_traverse_post_order (GTS_SPLIT (vs->v1), 
+					 depth, func, data))
+      return TRUE;
+    if (GTS_IS_SPLIT (vs->v2) &&
+	split_depth_traverse_post_order (GTS_SPLIT (vs->v2),
+					 depth, func, data))
+      return TRUE;
+  }
+  if (func (vs, data))
+    return TRUE;
+  return FALSE;
+}
+
+/**
+ * gts_split_traverse:
+ * @root: the #GtsSplit to start the traversal from.
+ * @order: the order in which nodes are visited - G_PRE_ORDER or G_POST_ORDER.
+ * @depth: the maximum depth of the traversal. Nodes below this depth
+ * will not be visited. If depth is -1 all nodes in the tree are
+ * visited. If depth is 1, only the root is visited. If depth is 2,
+ * the root and its children are visited. And so on.
+ * @func: the function to call for each visited #GtsHSplit.
+ * @data: user data to pass to the function.
+ *
+ * Traverses the #GtsSplit tree having @root as root. Calls @func for each
+ * #GtsSplit of the tree in the order specified by @order. If order is set
+ * to G_PRE_ORDER @func is called for the #GtsSplit then its children, if order
+ * is set to G_POST_ORDER @func is called for the children and then for the
+ * #GtsSplit.
+ */
+void gts_split_traverse (GtsSplit *           root,
+			 GTraverseType        order,
+			 gint                 depth,
+			 GtsSplitTraverseFunc func,
+			 gpointer             data)
+{
+  g_return_if_fail (root != NULL);
+  g_return_if_fail (func != NULL);
+  g_return_if_fail (order < G_LEVEL_ORDER);
+  g_return_if_fail (depth == -1 || depth > 0);
+
+  switch (order) {
+  case G_PRE_ORDER:
+    if (depth < 0)
+      split_traverse_pre_order (root, func, data);
+    else
+      split_depth_traverse_pre_order (root, depth, func, data);
+    break;
+  case G_POST_ORDER:
+    if (depth < 0)
+      split_traverse_post_order (root, func, data);
+    else
+      split_depth_traverse_post_order (root, depth, func, data);
+    break;
+  default:
+    g_assert_not_reached ();
+  }
+}
+
+/**
+ * gts_split_height:
+ * @root: a #GtsSplit.
+ *
+ * Returns: the maximum height of the vertex split tree having @root as root.
+ */
+guint gts_split_height (GtsSplit * root)
+{
+  guint height = 0, tmp_height;
+
+  g_return_val_if_fail (root != NULL, 0);
+
+  if (GTS_IS_SPLIT (root->v1)) {
+    tmp_height = gts_split_height (GTS_SPLIT (root->v1));
+    if (tmp_height > height)
+      height = tmp_height;
+  }
+  if (GTS_IS_SPLIT (root->v2)) {
+    tmp_height = gts_split_height (GTS_SPLIT (root->v2));
+    if (tmp_height > height)
+      height = tmp_height;
+  }
+
+  return height + 1;
+}
+
+#ifndef DYNAMIC_SPLIT
+static gboolean list_array_are_identical (GSList * list, 
+					  gpointer * array,
+					  gpointer excluded)
+{
+  while (list) {
+    gpointer data = list->data;
+    if (data != excluded) {
+      gboolean found = FALSE;
+      gpointer * a = array;
+      
+      while (!found && *a)
+	if (*(a++) == data)
+	  found = TRUE;
+      if (!found)
+	return FALSE;
+    }
+    list = list->next;
+  }
+  return TRUE;
+}
+#endif /* ifndef DYNAMIC_SPLIT */
+
+#ifndef NEW
+gboolean gts_split_is_collapsable (GtsSplit * vs)
+{
+  guint i;
+  GtsSplitCFace * cf;
+  GtsVertex * v1, * v2;
+  GtsEdge * e;
+
+  g_return_val_if_fail (vs != NULL, FALSE);
+
+  v1 = GTS_SPLIT_V1 (vs);
+  v2 = GTS_SPLIT_V2 (vs);
+  g_return_val_if_fail ((e = GTS_EDGE (gts_vertices_are_connected (v1, v2))),
+			FALSE);
+
+#ifdef DYNAMIC_SPLIT
+  if (!gts_edge_collapse_is_valid (e))
+    return FALSE;
+#else 
+  i = vs->ncf;
+  cf = vs->cfaces;
+  while (i--) {
+    GtsTriangle * t = GTS_TRIANGLE (cf->f);
+    GtsEdge * e1 = t->e1, * e2 = t->e2, * e3 = t->e3;
+
+    ROTATE_ORIENT (e, e1, e2, e3);
+    if (SEGMENT_USE_VERTEX (GTS_SEGMENT (e1), v2)) {
+      e3 = e1; e1 = e2; e2 = e3;
+    }
+
+    if (!list_array_are_identical (e1->triangles, (gpointer *) cf->a1, t))
+      return FALSE;
+    if (!list_array_are_identical (e2->triangles, (gpointer *) cf->a2, t))
+      return FALSE;
+    
+    cf++;
+  }
+#endif
+  return TRUE;
+}
+#endif /* not NEW */
+
+#ifdef DEBUG_HEXPAND
+static guint expand_level = 0;
+
+static void expand_indent (FILE * fptr)
+{
+  guint i = expand_level;
+  while (i--)
+    fputc (' ', fptr);
+}
+#endif
+
+/**
+ * gts_hsplit_force_expand:
+ * @hs: a #GtsHSplit.
+ * @hsurface: a #GtsHSurface.
+ *
+ * Forces the expansion of @hs by first expanding all its dependencies not
+ * already expanded.
+ */
+void gts_hsplit_force_expand (GtsHSplit * hs,
+			      GtsHSurface * hsurface)
+{
+  guint i;
+  GtsSplitCFace * cf;
+
+  g_return_if_fail (hs != NULL);
+  g_return_if_fail (hsurface != NULL);
+  g_return_if_fail (hs->nchild == 0);
+
+#ifdef DEBUG_HEXPAND
+  expand_level += 2;
+#endif
+
+  if (hs->parent && hs->parent->nchild == 0) {
+#ifdef DEBUG_HEXPAND
+    expand_indent (stderr); 
+    fprintf (stderr, "expand parent %p\n", hs->parent);
+#endif
+    gts_hsplit_force_expand (hs->parent, hsurface);
+  }
+
+  i = GTS_SPLIT (hs)->ncf;
+  cf = GTS_SPLIT (hs)->cfaces;
+  while (i--) {
+    GtsTriangle ** j, * t;
+
+    j = cf->a1;
+    while ((t = *(j++)))
+      if (IS_CFACE (t)) {
+#ifdef DEBUG_HEXPAND
+	expand_indent (stderr); 
+	fprintf (stderr, "expand a1: cf->f: %p t: %p parent_split: %p\n", 
+		 cf->f,
+		 t,
+		 GTS_HSPLIT (CFACE (t)->parent_split));
+#endif
+	gts_hsplit_force_expand (GTS_HSPLIT (CFACE (t)->parent_split),
+				 hsurface);
+#ifdef DEBUG_HEXPAND
+	g_assert (!IS_CFACE (t));
+#endif
+      }
+    j = cf->a2;
+    while ((t = *(j++)))
+      if (IS_CFACE (t)) {
+#ifdef DEBUG_HEXPAND
+	expand_indent (stderr); 
+	fprintf (stderr, "expand a2: cf->f: %p t: %p parent_split: %p\n", 
+		 cf->f,
+		 t,
+		 GTS_HSPLIT (CFACE (t)->parent_split));
+#endif
+	gts_hsplit_force_expand (GTS_HSPLIT (CFACE (t)->parent_split),
+				 hsurface);
+      }
+    cf++;
+  }
+
+  gts_hsplit_expand (hs, hsurface);
+
+#ifdef DEBUG_HEXPAND
+  expand_level -= 2; 
+  expand_indent (stderr); 
+  fprintf (stderr, "%p expanded\n", hs);
+#endif
+}
+
+static void index_object (GtsObject * o, guint * n)
+{
+  o->reserved = GUINT_TO_POINTER ((*n)++);
+}
+
+static void index_face (GtsFace * f, gpointer * data)
+{
+  guint * nf = data[1];
+
+  g_hash_table_insert (data[0], f, GUINT_TO_POINTER ((*nf)++));
+}
+
+/**
+ * gts_psurface_write:
+ * @ps: a #GtsPSurface.
+ * @fptr: a file pointer.
+ *
+ * Writes to @fptr a GTS progressive surface description.
+ */
+void gts_psurface_write (GtsPSurface * ps, FILE * fptr)
+{
+  guint nv = 1;
+  guint nf = 1;
+  GHashTable * hash;
+  gpointer data[2];
+
+  g_return_if_fail (ps != NULL);
+  g_return_if_fail (fptr != NULL);
+  g_return_if_fail (GTS_PSURFACE_IS_CLOSED (ps));
+
+  while (gts_psurface_remove_vertex (ps))
+    ;
+
+  GTS_POINT_CLASS (ps->s->vertex_class)->binary = FALSE;
+  gts_surface_write (ps->s, fptr);
+  
+  gts_surface_foreach_vertex (ps->s, (GtsFunc) index_object, &nv);
+  hash = g_hash_table_new (NULL, NULL);
+  data[0] = hash;
+  data[1] = &nf;
+  gts_surface_foreach_face (ps->s, (GtsFunc) index_face, data);
+
+  fprintf (fptr, "%u\n", ps->split->len);
+  while (ps->pos) {
+    GtsSplit * vs = g_ptr_array_index (ps->split, --ps->pos);
+    GtsSplitCFace * scf = vs->cfaces;
+    GtsVertex * v1, * v2;
+    guint i = vs->ncf;
+
+    fprintf (fptr, "%u %u",
+	     GPOINTER_TO_UINT (GTS_OBJECT (vs->v)->reserved),
+	     vs->ncf);
+    if (GTS_OBJECT (vs)->klass->write)
+      (*GTS_OBJECT (vs)->klass->write) (GTS_OBJECT (vs), fptr);
+    fputc ('\n', fptr);
+
+    v1 = GTS_IS_SPLIT (vs->v1) ? GTS_SPLIT (vs->v1)->v : GTS_VERTEX (vs->v1);
+    GTS_OBJECT (v1)->reserved = GUINT_TO_POINTER (nv++);
+    v2 = GTS_IS_SPLIT (vs->v2) ? GTS_SPLIT (vs->v2)->v : GTS_VERTEX (vs->v2);
+    GTS_OBJECT (v2)->reserved = GUINT_TO_POINTER (nv++);
+
+    (*GTS_OBJECT (v1)->klass->write) (GTS_OBJECT (v1), fptr);
+    fputc ('\n', fptr);
+
+    (*GTS_OBJECT (v2)->klass->write) (GTS_OBJECT (v2), fptr);
+    fputc ('\n', fptr);
+    
+    while (i--) {
+      CFace * cf = CFACE (scf->f);
+      GtsTriangle ** a, * t;
+
+      fprintf (fptr, "%u %u",
+	       GPOINTER_TO_UINT (g_hash_table_lookup (hash, cf->t)),
+	       cf->flags);
+      if (GTS_OBJECT_CLASS (ps->s->face_class)->write)
+	(*GTS_OBJECT_CLASS (ps->s->face_class)->write) (GTS_OBJECT (cf), fptr);
+      fputc ('\n', fptr);
+
+      a = scf->a1;
+      while ((t = *(a++)))
+	fprintf (fptr, "%u ",
+		 GPOINTER_TO_UINT (g_hash_table_lookup (hash, t)));
+      fprintf (fptr, "\n");
+
+      a = scf->a2;
+      while ((t = *(a++)))
+	fprintf (fptr, "%u ",
+		 GPOINTER_TO_UINT (g_hash_table_lookup (hash, t)));
+      fprintf (fptr, "\n");
+
+      g_hash_table_insert (hash, cf, GUINT_TO_POINTER (nf++));
+
+      scf++;
+    }
+
+    gts_split_expand (vs, ps->s, ps->s->edge_class);
+  }
+
+  gts_surface_foreach_vertex (ps->s, 
+			      (GtsFunc) gts_object_reset_reserved, NULL);
+  g_hash_table_destroy (hash);
+}
+
+static guint surface_read (GtsSurface * surface, 
+			   GtsFile * f,
+			   GPtrArray * vertices,
+			   GPtrArray * faces)
+{
+  GtsEdge ** edges;
+  guint n, nv, ne, nf;
+
+  g_return_val_if_fail (surface != NULL, 1);
+  g_return_val_if_fail (f != NULL, 1);
+  
+  if (f->type != GTS_INT) {
+    gts_file_error (f, "expecting an integer (number of vertices)");
+    return f->line;
+  }
+  nv = atoi (f->token->str);
+
+  gts_file_next_token (f);
+  if (f->type != GTS_INT) {
+    gts_file_error (f, "expecting an integer (number of edges)");
+    return f->line;
+  }
+  ne = atoi (f->token->str);
+
+  gts_file_next_token (f);
+  if (f->type != GTS_INT) {
+    gts_file_error (f, "expecting an integer (number of faces)");
+    return f->line;
+  }
+  nf = atoi (f->token->str);
+
+  gts_file_next_token (f);
+  if (f->type == GTS_STRING) {
+    if (f->type != GTS_STRING) {
+      gts_file_error (f, "expecting a string (GtsSurfaceClass)");
+      return f->line;
+    }
+    gts_file_next_token (f);
+    if (f->type != GTS_STRING) {
+      gts_file_error (f, "expecting a string (GtsFaceClass)");
+      return f->line;
+    }
+    gts_file_next_token (f);
+    if (f->type != GTS_STRING) {
+      gts_file_error (f, "expecting a string (GtsEdgeClass)");
+      return f->line;
+    }
+    gts_file_next_token (f);
+    if (f->type != GTS_STRING) {
+      gts_file_error (f, "expecting a string (GtsVertexClass)");
+      return f->line;
+    }
+    if (!strcmp (f->token->str, "GtsVertexBinary"))
+      GTS_POINT_CLASS (surface->vertex_class)->binary = TRUE;
+    else
+      gts_file_first_token_after (f, '\n');
+  }
+  else
+    gts_file_first_token_after (f, '\n');
+
+  g_ptr_array_set_size (vertices, nv);
+  g_ptr_array_set_size (faces, nf);
+  /* allocate nv + 1 just in case nv == 0 */
+  edges = g_malloc ((ne + 1)*sizeof (GtsEdge *));
+  
+  n = 0;
+  while (n < nv && f->type != GTS_ERROR) {
+    GtsObject * new_vertex =
+      gts_object_new (GTS_OBJECT_CLASS (surface->vertex_class));
+
+    (* GTS_OBJECT_CLASS (surface->vertex_class)->read) (&new_vertex, f);
+    if (f->type != GTS_ERROR) {
+      if (!GTS_POINT_CLASS (surface->vertex_class)->binary)
+	gts_file_first_token_after (f, '\n');
+      g_ptr_array_index (vertices, n++) = new_vertex;
+    }
+    else
+      gts_object_destroy (new_vertex);
+  }
+  if (f->type == GTS_ERROR)
+    nv = n;
+  if (GTS_POINT_CLASS (surface->vertex_class)->binary)
+    gts_file_first_token_after (f, '\n');
+
+  n = 0;
+  while (n < ne && f->type != GTS_ERROR) {
+    guint p1, p2;
+
+    if (f->type != GTS_INT)
+      gts_file_error (f, "expecting an integer (first vertex index)");
+    else {
+      p1 = atoi (f->token->str);
+      if (p1 == 0 || p1 > nv)
+	gts_file_error (f, "vertex index `%d' is out of range `[1,%d]'", 
+			p1, nv);
+      else {
+	gts_file_next_token (f);
+	if (f->type != GTS_INT)
+	  gts_file_error (f, "expecting an integer (second vertex index)");
+	else {
+	  p2 = atoi (f->token->str);
+	  if (p2 == 0 || p2 > nv)
+	    gts_file_error (f, "vertex index `%d' is out of range `[1,%d]'", 
+			    p2, nv);
+	  else {
+	    GtsEdge * new_edge =
+	      gts_edge_new (surface->edge_class,
+			    g_ptr_array_index (vertices, p1 - 1),
+			    g_ptr_array_index (vertices, p2 - 1));
+
+	    gts_file_next_token (f);
+	    if (f->type != '\n')
+	      if (GTS_OBJECT_CLASS (surface->edge_class)->read)
+		(*GTS_OBJECT_CLASS (surface->edge_class)->read)
+		  ((GtsObject **) &new_edge, f);
+	    gts_file_first_token_after (f, '\n');
+	    edges[n++] = new_edge;
+	  }
+	}
+      }
+    }
+  }
+  if (f->type == GTS_ERROR)
+    ne = n;
+
+  n = 0;
+  while (n < nf && f->type != GTS_ERROR) {
+    guint s1, s2, s3;
+
+    if (f->type != GTS_INT)
+      gts_file_error (f, "expecting an integer (first edge index)");
+    else {
+      s1 = atoi (f->token->str);
+      if (s1 == 0 || s1 > ne)
+	gts_file_error (f, "edge index `%d' is out of range `[1,%d]'", 
+			s1, ne);
+      else {
+	gts_file_next_token (f);
+	if (f->type != GTS_INT)
+	  gts_file_error (f, "expecting an integer (second edge index)");
+	else {
+	  s2 = atoi (f->token->str);
+	  if (s2 == 0 || s2 > ne)
+	    gts_file_error (f, "edge index `%d' is out of range `[1,%d]'", 
+			    s2, ne);
+	  else {
+	    gts_file_next_token (f);
+	    if (f->type != GTS_INT)
+	      gts_file_error (f, "expecting an integer (third edge index)");
+	    else {
+	      s3 = atoi (f->token->str);
+	      if (s3 == 0 || s3 > ne)
+		gts_file_error (f, "edge index `%d' is out of range `[1,%d]'", 
+				s3, ne);
+	      else {
+		GtsFace * new_face = gts_face_new (surface->face_class,
+						   edges[s1 - 1],
+						   edges[s2 - 1],
+						   edges[s3 - 1]);
+
+		gts_file_next_token (f);
+		if (f->type != '\n')
+		  if (GTS_OBJECT_CLASS (surface->face_class)->read)
+		    (*GTS_OBJECT_CLASS (surface->face_class)->read)
+		      ((GtsObject **) &new_face, f);
+		gts_file_first_token_after (f, '\n');
+		gts_surface_add_face (surface, new_face);
+		g_ptr_array_index (faces, n++) = new_face;
+	      }
+	    }
+	  }
+	}
+      }
+    }
+  }
+
+  g_free (edges);
+
+  if (f->type == GTS_ERROR) {
+    gts_allow_floating_vertices = TRUE;
+    while (nv)
+      gts_object_destroy (GTS_OBJECT (g_ptr_array_index (vertices, nv-- - 1)));
+    gts_allow_floating_vertices = FALSE;    
+    return f->line;
+  }
+
+  return 0;
+}
+
+/**
+ * gts_psurface_open:
+ * @klass: a #GtsPSurfaceClass.
+ * @s: a #GtsSurface.
+ * @split_class: a #GtsSplitClass to use for the #GtsSplit.
+ * @f: a #GtsFile.
+ *
+ * Creates a new #GtsPSurface prepared for input from the file @f 
+ * containing a valid GTS representation of a progressive surface. The initial
+ * shape of the progressive surface is loaded into @s.
+ * 
+ * Before being usable as such this progressive surface must be closed using
+ * gts_psurface_close(). While open however, the functions
+ * gts_psurface_get_vertex_number(), gts_psurface_min_vertex_number() and
+ * gts_psurface_max_vertex_number() can still be used.
+ *
+ * Returns: a new #GtsPSurface or %NULL if there was a format error while
+ * reading the file, in which case @f contains information about the error.
+ */
+GtsPSurface * gts_psurface_open (GtsPSurfaceClass * klass,
+				 GtsSurface * s,
+				 GtsSplitClass * split_class,
+				 GtsFile * f)
+{
+  GtsPSurface * ps;
+
+  g_return_val_if_fail (klass != NULL, NULL);
+  g_return_val_if_fail (s != NULL, NULL);
+  g_return_val_if_fail (split_class != NULL, NULL);
+  g_return_val_if_fail (f != NULL, NULL);
+
+  ps = GTS_PSURFACE (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  ps->s = s;
+  ps->split_class = split_class;
+
+  ps->vertices = g_ptr_array_new ();
+  ps->faces = g_ptr_array_new ();
+
+  if (surface_read (s, f, ps->vertices, ps->faces)) {
+    ps->s = NULL;
+    gts_object_destroy (GTS_OBJECT (ps));
+    return NULL;
+  }
+
+  ps->min = gts_surface_vertex_number (ps->s);
+  ps->pos = 0;
+
+  if (f->type == GTS_INT) {
+    gint ns = atoi (f->token->str);
+    
+    if (ns > 0) {
+      g_ptr_array_set_size (ps->split, ns);
+      gts_file_first_token_after (f, '\n');
+    }
+  }
+
+  return ps;
+}
+
+/**
+ * gts_psurface_read_vertex:
+ * @ps: a #GtsPSurface prealably created with gts_psurface_open().
+ * @fp: a #GtsFile.
+ *
+ * Reads in one vertex split operation from @fp and performs the expansion.
+ *
+ * If an error occurs while reading the file, the @error field of @fp is set.
+ *
+ * Returns: the newly created #GtsSplit or %NULL if no vertex split could be
+ * read from @fp.
+ */
+GtsSplit * gts_psurface_read_vertex (GtsPSurface * ps, GtsFile * fp)
+{
+  guint nv, ncf;
+  GtsSplit * vs, * parent;
+  GtsSplitCFace * scf;
+
+  g_return_val_if_fail (ps != NULL, NULL);
+  g_return_val_if_fail (fp != NULL, NULL);
+  g_return_val_if_fail (!GTS_PSURFACE_IS_CLOSED (ps), NULL);
+  
+  if (ps->pos >= ps->split->len)
+    return NULL;
+
+  if (fp->type == GTS_NONE)
+    return NULL;
+  if (fp->type != GTS_INT) {
+    gts_file_error (fp, "expecting an integer (vertex index)");
+    return NULL;
+  }
+  nv = atoi (fp->token->str);
+  if (nv == 0 || nv > ps->vertices->len) {
+    gts_file_error (fp, "vertex index `%d' is out of range `[1,%d]'",
+		    nv, ps->vertices->len);
+    return NULL;
+  }
+
+  gts_file_next_token (fp);
+  if (fp->type != GTS_INT) {
+    gts_file_error (fp, "expecting an integer (ncf)");
+    return NULL;
+  }
+  ncf = atoi (fp->token->str);
+  
+  vs = GTS_SPLIT (gts_object_new (GTS_OBJECT_CLASS (ps->split_class)));
+
+  vs->v = g_ptr_array_index (ps->vertices, nv - 1);
+  vs->v1 = vs->v2 = NULL;
+  vs->cfaces = NULL;
+  vs->ncf = 0;
+
+  gts_file_next_token (fp);
+  if (fp->type != '\n')
+    if (GTS_OBJECT (vs)->klass->read)
+      (* GTS_OBJECT (vs)->klass->read) ((GtsObject **) &vs, fp);
+  gts_file_first_token_after (fp, '\n');
+
+  if (fp->type != GTS_ERROR) {
+    vs->v1 = gts_object_new (GTS_OBJECT_CLASS (ps->s->vertex_class));
+    (* GTS_OBJECT_CLASS (ps->s->vertex_class)->read) (&(vs->v1), fp);
+    if (fp->type != GTS_ERROR) {
+      vs->v1->reserved = vs;
+      g_ptr_array_add (ps->vertices, vs->v1);
+
+      gts_file_first_token_after (fp, '\n');
+      
+      vs->v2 = gts_object_new (GTS_OBJECT_CLASS (ps->s->vertex_class));
+      (*GTS_OBJECT_CLASS (ps->s->vertex_class)->read) (&(vs->v2), fp);
+      if (fp->type != GTS_ERROR) {
+	vs->v2->reserved = vs;
+	g_ptr_array_add (ps->vertices, vs->v2);
+	gts_file_first_token_after (fp, '\n');
+      }
+    }
+  }
+
+  if (fp->type != GTS_ERROR) {
+    scf = vs->cfaces = g_malloc (sizeof (GtsSplitCFace)*ncf);
+    while (fp->type != GTS_ERROR && ncf--) {
+      guint it, flags;
+      GtsFace * f;
+      CFace * cf;
+      GPtrArray * a;
+
+      if (fp->type != GTS_INT)
+	gts_file_error (fp, "expecting an integer (face index)");
+      else {
+	it = atoi (fp->token->str);
+	if (it == 0 || it > ps->faces->len)
+	  gts_file_error (fp, "face index `%d' is out of range `[1,%d]'",
+			  it, ps->faces->len);
+	else {
+	  gts_file_next_token (fp);
+	  if (fp->type != GTS_INT)
+	    gts_file_error (fp, "expecting an integer (flags)");
+	  else {
+	    flags = atoi (fp->token->str);
+	    f = 
+	      GTS_FACE (gts_object_new (GTS_OBJECT_CLASS (ps->s->face_class)));
+
+	    gts_file_next_token (fp);
+	    if (fp->type != '\n')
+	      if (GTS_OBJECT (f)->klass->read)
+		(*GTS_OBJECT (f)->klass->read) ((GtsObject **) &f, fp);
+	    gts_file_first_token_after (fp, '\n');
+	    if (fp->type != GTS_ERROR) {
+	      scf->f = f;
+
+	      cf = (CFace *) f;
+	      GTS_OBJECT (cf)->klass = GTS_OBJECT_CLASS (cface_class ());
+	      cf->parent_split = vs;
+	      cf->t = g_ptr_array_index (ps->faces, it - 1);
+	      cf->flags = flags;
+	  
+	      a = g_ptr_array_new ();
+	      do {
+		if (fp->type != GTS_INT)
+		  gts_file_error (fp, "expecting an integer (face index)");
+		else {
+		  it = atoi (fp->token->str);
+		  if (it > ps->faces->len)
+		    gts_file_error (fp, 
+				    "face index `%d' is out of range `[1,%d]'",
+				    it, ps->faces->len);
+		  else {
+		    g_ptr_array_add (a, g_ptr_array_index (ps->faces, 
+							   it - 1));
+		    gts_file_next_token (fp);
+		  }
+		}
+	      } while (fp->type != GTS_ERROR && fp->type != '\n');
+	      gts_file_first_token_after (fp, '\n');
+	      g_ptr_array_add (a, NULL);
+	      scf->a1 = (GtsTriangle **) a->pdata;
+	      g_ptr_array_free (a, FALSE);
+
+	      if (fp->type != GTS_ERROR) {
+		a = g_ptr_array_new ();
+		do {
+		  if (fp->type != GTS_INT)
+		    gts_file_error (fp, "expecting an integer (face index)");
+		  else {
+		    it = atoi (fp->token->str);
+		    if (it > ps->faces->len)
+		      gts_file_error (fp, 
+				   "face index `%d' is out of range `[1,%d]'",
+				      it, ps->faces->len);
+		    else {
+		      g_ptr_array_add (a, g_ptr_array_index (ps->faces, 
+							     it - 1));
+		      gts_file_next_token (fp);
+		    }
+		  }
+		} while (fp->type != GTS_ERROR && fp->type != '\n');
+		gts_file_first_token_after (fp, '\n');
+		g_ptr_array_add (a, NULL);
+		scf->a2 = (GtsTriangle **) a->pdata;
+		g_ptr_array_free (a, FALSE);
+		
+		g_ptr_array_add (ps->faces, f);
+	      
+		vs->ncf++;
+		scf++;
+	      }
+	    }
+	  }
+	}
+      }
+    }
+  }
+
+  if (fp->type != GTS_ERROR) {
+    if ((parent = GTS_OBJECT (vs->v)->reserved)) {
+      GTS_OBJECT (vs->v)->reserved = NULL;
+      if (parent->v1 == GTS_OBJECT (vs->v))
+	parent->v1 = GTS_OBJECT (vs);
+      else {
+	g_assert (parent->v2 == GTS_OBJECT (vs->v));
+	parent->v2 = GTS_OBJECT (vs);
+      }
+    }
+    g_ptr_array_index (ps->split, ps->pos++) = vs;
+    gts_split_expand (vs, ps->s, ps->s->edge_class);
+
+    return vs;
+  }
+
+  if (vs->v1) gts_object_destroy (vs->v1);
+  if (vs->v2) gts_object_destroy (vs->v2);
+  gts_object_destroy (GTS_OBJECT (vs));
+  
+  return NULL;
+}
+
+/**
+ * gts_psurface_close:
+ * @ps: a #GtsPSurface prealably created with gts_psurface_open().
+ *
+ * Closes a progressive surface.
+ */
+void gts_psurface_close (GtsPSurface * ps)
+{
+  g_return_if_fail (ps != NULL);
+  g_return_if_fail (!GTS_PSURFACE_IS_CLOSED (ps));
+
+  g_ptr_array_free (ps->vertices, TRUE);
+  g_ptr_array_free (ps->faces, TRUE);
+  ps->faces = ps->vertices = NULL;
+  
+  gts_surface_foreach_vertex (ps->s, 
+			      (GtsFunc) gts_object_reset_reserved, NULL);
+  if (ps->pos > 0)
+    g_ptr_array_set_size (ps->split, ps->pos);
+  if (ps->split->len > 1) {
+    guint i, half = ps->split->len/2, n = ps->split->len - 1;
+    
+    for (i = 0; i < half; i++) {
+      gpointer p1 = g_ptr_array_index (ps->split, i);
+      gpointer p2 = g_ptr_array_index (ps->split, n - i);
+      g_ptr_array_index (ps->split, n - i) = p1;
+      g_ptr_array_index (ps->split, i) = p2;
+    }
+  }
+  ps->pos = 0;
+}
diff --git a/gts/stripe.c b/gts/stripe.c
new file mode 100644
index 0000000..7e98a9c
--- /dev/null
+++ b/gts/stripe.c
@@ -0,0 +1,766 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999-2003  Wagner Toledo Correa, Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "gts.h"
+
+#define PRINT_HEAP_ELEMENTS 0
+
+typedef struct {
+  GtsTriangle * t;
+  gboolean used;
+  GSList * neighbors;
+  GtsEHeapPair *pos;
+} tri_data_t;
+
+typedef struct {
+  GHashTable * ht;
+} map_t;
+
+typedef struct {
+  map_t * map;
+  GtsEHeap * heap;
+} heap_t;
+
+static tri_data_t    * tri_data_new (GtsTriangle * t);
+static void            tri_data_destroy (tri_data_t * td);
+static guint           tri_data_num_unused_neighbors2 (const tri_data_t * td,
+						       const map_t * map);
+static GHashTable    * tri_data_unused_neighbors2 (const tri_data_t * td,
+						   const map_t * map);
+
+static map_t         * map_new (GtsSurface * s);
+static void            map_destroy (map_t * map);
+static tri_data_t    * map_lookup (const map_t * map, GtsTriangle * t);
+
+
+static heap_t        * heap_new (GtsSurface * s);
+static void            heap_destroy (heap_t * heap);
+static gboolean        heap_is_empty (const heap_t * heap);
+static GtsTriangle   * heap_top (const heap_t * heap);
+static void            heap_remove (heap_t * heap, GtsTriangle * t);
+
+/* helper functions */
+
+static gboolean vertices_are_unique (GtsVertex * v1,
+				     GtsVertex * v2,
+				     GtsVertex * v3)
+{
+  g_assert (v1 && v2 && v3);
+  return (v1 != v2 && v1 != v3 && v2 != v3);
+}
+
+static gboolean vertex_is_one_of (GtsVertex * v,
+				  GtsVertex * v1,
+				  GtsVertex * v2,
+				  GtsVertex * v3)
+{
+  g_assert (v && v1 && v2 && v3);
+  return v == v1 || v == v2 || v == v3;
+}
+
+static guint num_shared_vertices (GtsVertex * u1,
+				  GtsVertex * u2,
+				  GtsVertex * u3,
+				  GtsVertex * v1,
+				  GtsVertex * v2,
+				  GtsVertex * v3)
+{
+  guint n = 0;
+  
+  g_assert (u1 && u2 && u3);
+  g_assert (v1 && v2 && v3);
+  g_assert (vertices_are_unique (u1, u2, u3));
+  g_assert (vertices_are_unique (v1, v2, v3));
+  
+  if (vertex_is_one_of (v1, u1, u2, u3))
+    n++;
+  if (vertex_is_one_of (v2, u1, u2, u3))
+    n++;
+  if (vertex_is_one_of (v3, u1, u2, u3))
+    n++;
+  return n;
+}
+
+static gboolean vertices_match (GtsVertex * v1,
+				GtsVertex * v2,
+				GtsVertex * v3,
+				GtsVertex ** v4,
+				GtsVertex ** v5,
+				GtsVertex ** v6)
+{
+  guint i;
+
+  g_assert (v4 && v5 && v6);
+  g_assert (*v4 && *v5 && *v6);
+  g_assert (vertices_are_unique (*v4, *v5, *v6));
+  
+  for (i = 0; i < 2; i++) {
+    if ((!v1 || (v1 == *v4)) &&
+	(!v2 || (v2 == *v5)) &&
+	(!v3 || (v3 == *v6)))
+      return TRUE;
+    else {
+      GtsVertex * v7 = * v4;
+
+      *v4 = *v5;
+      *v5 = *v6;
+      *v6 = v7;
+    }
+  }
+  return ((!v1 || (v1 == *v4)) &&
+	  (!v2 || (v2 == *v5)) &&
+	  (!v3 || (v3 == *v6)));
+}
+
+static GtsVertex * non_shared_vertex1 (GtsVertex * u1,
+				       GtsVertex * u2,
+				       GtsVertex * u3,
+				       GtsVertex * v1,
+				       GtsVertex * v2,
+				       GtsVertex * v3)
+{
+  GtsVertex * u = NULL;
+
+  g_assert (u1 && u2 && u3);
+  g_assert (v1 && v2 && v3);
+  g_assert (vertices_are_unique (u1, u2, u3));
+  g_assert (vertices_are_unique (v1, v2, v3));
+  g_assert (num_shared_vertices (u1, u2, u3, v1, v2, v3) == 2);
+
+  if (!vertex_is_one_of (u1, v1, v2, v3)) {
+    g_assert (vertex_is_one_of (u2, v1, v2, v3));
+    g_assert (vertex_is_one_of (u3, v1, v2, v3));
+    u = u1;
+  } else if (!vertex_is_one_of (u2, v1, v2, v3)) {
+    g_assert (vertex_is_one_of (u1, v1, v2, v3));
+    g_assert (vertex_is_one_of (u3, v1, v2, v3));
+    u = u2;
+  } else if (!vertex_is_one_of (u3, v1, v2, v3)) {
+    g_assert (vertex_is_one_of (u1, v1, v2, v3));
+    g_assert (vertex_is_one_of (u2, v1, v2, v3));
+    u = u3;
+  } else 
+    g_assert_not_reached ();
+
+  return u;
+}
+
+static void match_vertex (GtsVertex * v,
+			  GtsVertex ** v1,
+			  GtsVertex ** v2,
+			  GtsVertex ** v3)
+{
+  g_assert (v && v1 && v2 && v3);
+  g_assert (*v1 && *v2 && *v3);
+  g_assert (vertex_is_one_of (v, *v1, *v2, *v3));
+  while (*v1 != v) {
+    GtsVertex *v0 = *v1;
+
+    *v1 = *v2;
+    *v2 = *v3;
+    *v3 = v0;
+  }
+}
+
+/* tri_data_t functions */
+
+static tri_data_t * tri_data_new (GtsTriangle * t)
+{
+  tri_data_t * td;
+  
+  td = g_malloc (sizeof (tri_data_t));
+  td->t = t;
+  td->used = FALSE;
+  td->neighbors = gts_triangle_neighbors (t);
+  td->pos = NULL;
+
+  return td;
+}
+
+static void tri_data_destroy (tri_data_t * td)
+{
+  if (!td)
+    return;
+  g_slist_free (td->neighbors);
+  g_free (td);
+}
+
+static guint tri_data_num_unused_neighbors2 (const tri_data_t * td,
+					     const map_t * map)
+{
+  GHashTable *h;
+  guint n;
+
+  g_assert (td);
+  g_assert (map);
+  h = tri_data_unused_neighbors2 (td, map);
+  n = g_hash_table_size (h);
+  g_hash_table_destroy (h);
+  return n;
+}
+
+static void copy_key_to_array (gpointer key,
+			       gpointer value,
+			       gpointer user_data)
+{
+  GtsTriangle * t = key;
+  GtsTriangle *** p = user_data;
+
+  (void) value;
+  g_assert (t);
+  g_assert (p && *p);
+  **p = t;
+  (*p)++;
+}
+
+static gboolean are_neighbors_unique (GHashTable *h)
+{
+  GtsTriangle ** a;
+  GtsTriangle ** p;
+  gint i, j, n;		/* guint won't work if n == 0 */
+
+  g_assert (h);
+  n = g_hash_table_size (h);
+#ifdef DEBUG
+  if (n > 9)
+    g_warning ("triangle has %d 2-level neighbors", n);
+#endif /* DEBUG */
+  a = g_malloc(n*sizeof (GtsTriangle *));
+  p = a;
+  g_hash_table_foreach (h, copy_key_to_array, &p);
+  for (i = 0; i < n - 1; i++) {
+    g_assert (a[i]);
+    for (j = i + 1; j < n; j++) {
+      g_assert (a[j]);
+      if (a[i] == a[j]) {
+	g_free (a);
+	return FALSE;
+      }
+    }
+  }
+  g_free (a);
+  return TRUE;
+}
+
+static GHashTable * tri_data_unused_neighbors2 (const tri_data_t * td,
+						const map_t * map)
+{
+  GHashTable * h = g_hash_table_new (NULL, NULL);
+  GSList * li;
+
+  g_assert (td);
+  g_assert (map);
+  for (li = td->neighbors; li != NULL; li = li->next) {
+    GtsTriangle * t2 = li->data;
+    tri_data_t * td2 = map_lookup (map, t2);
+    GSList * lj;
+
+    g_assert (td2);
+    if (!td2->used) {
+      g_hash_table_insert (h, t2, td2);
+      for (lj = td2->neighbors; lj != NULL; lj = lj->next) {
+	GtsTriangle * t3 = lj->data;
+	tri_data_t * td3 = map_lookup (map, t3);
+
+	g_assert (td3);
+	if (td3 != td && !td3->used)
+	  g_hash_table_insert (h, t3, td3);
+      }
+    }
+  }
+  g_assert (are_neighbors_unique (h));
+  return h;
+}
+
+#if PRINT_HEAP_ELEMENTS
+static void tri_data_print (const tri_data_t * td, FILE * fp)
+{
+  g_assert (td);
+  g_assert (fp);
+  fprintf(fp, "td=%p t=%p used=%d pos=%p key=%f\n",
+	  td, td->t, td->used, td->pos,
+	  td->pos ? td->pos->key : -1.0);
+}
+#endif /* PRINT_HEAP_ELEMENTS */
+
+/* heap_t functions */
+
+static gdouble triangle_priority (gpointer item, gpointer data)
+{
+  GtsTriangle * t = item;
+  map_t * map = data;
+  tri_data_t * td;
+  gdouble k;
+  
+  g_assert (t);
+  g_assert (map);
+  td = map_lookup (map, t);
+  g_assert (td);
+  k = tri_data_num_unused_neighbors2 (td, map);
+  return k;
+}
+
+#if PRINT_HEAP_ELEMENTS
+static void print_heap_element (gpointer data, gpointer user_data)
+{
+  GtsTriangle * t = data;
+  map_t * map = user_data;
+  tri_data_t * td;
+  
+  g_assert (t);
+  g_assert (map);
+  td = map_lookup (map, t);
+  g_assert (td);
+  g_assert (!td->used);
+  g_assert (td->pos);
+  tri_data_print (td, stderr);
+}
+#endif /* PRINT_HEAP_ELEMENTS */
+
+static void insert_entry_into_heap (gpointer key,
+				    gpointer value,
+				    gpointer user_data)
+{
+  GtsTriangle * t = key;
+  tri_data_t * td = value;
+  GtsEHeap * heap = user_data;
+  
+  g_assert (!td->pos);
+  td->pos = gts_eheap_insert (heap, t);
+  g_assert (td->pos);
+}
+
+static heap_t * heap_new (GtsSurface *s)
+{
+  heap_t * heap;
+
+  g_assert (s);
+  heap = g_malloc (sizeof (heap_t));
+  heap->map = map_new (s);
+  heap->heap = gts_eheap_new (triangle_priority, heap->map);
+  g_hash_table_foreach (heap->map->ht,
+			insert_entry_into_heap,
+			heap->heap);
+#if PRINT_HEAP_ELEMENTS
+  gts_eheap_foreach (heap->heap, print_heap_element, heap->map);
+#endif /* PRINT_HEAP_ELEMENTS */
+  return heap;
+}
+
+static void heap_destroy (heap_t * heap)
+{
+  if (!heap)
+    return;
+  map_destroy (heap->map);
+  gts_eheap_destroy (heap->heap);
+  g_free (heap);
+}
+
+static gboolean heap_is_empty (const heap_t * heap)
+{
+  g_assert (heap);
+  g_assert (heap->heap);
+  return gts_eheap_size (heap->heap) == 0;
+}
+
+typedef struct {
+  const heap_t * heap;
+  double min_key;
+} min_key_t;
+
+static GtsTriangle * heap_top (const heap_t * heap)
+{
+  GtsTriangle * t;
+  
+  g_assert (heap);
+  g_assert (heap->heap);
+  t = gts_eheap_top (heap->heap, NULL);
+  return t;
+}
+
+static void decrease_key (gpointer key, gpointer value, gpointer user_data)
+{
+  GtsTriangle * t = key;
+  tri_data_t * td = value;
+  heap_t *heap = user_data;
+  gdouble k;
+  
+  (void) t;
+  g_assert (heap);
+  g_assert (heap->map);
+  g_assert (heap->heap);
+  g_assert (td);
+  g_assert (!td->used);
+  g_assert (td->pos);
+  
+  k = tri_data_num_unused_neighbors2 (td, heap->map);
+  g_assert (k <= td->pos->key);
+#ifdef DEBUG
+  if (k == td->pos->key)
+    g_warning ("same key: %f\n", k);
+#endif /* DEBUG */
+  if (k != td->pos->key) {
+    g_assert (k < td->pos->key);
+    g_assert (k >= 0.0);
+    gts_eheap_decrease_key (heap->heap, td->pos, k);
+  }
+}
+
+static void heap_remove (heap_t * heap, GtsTriangle * t)
+{
+  tri_data_t * td;
+  GHashTable * h;
+  
+  g_assert (heap);
+  g_assert (t);
+  td = map_lookup (heap->map, t);
+  g_assert (td);
+  g_assert (!td->used);
+  g_assert (td->pos);
+  td->used = TRUE;
+  gts_eheap_remove (heap->heap, td->pos);
+  td->pos = NULL;
+  
+  /*	fprintf(stderr, "td: %p\n", td); */
+  h = tri_data_unused_neighbors2 (td, heap->map);
+  g_hash_table_foreach (h, decrease_key, heap);
+  g_hash_table_destroy (h);
+}
+
+/* map_t functions */
+
+static gint create_map_entry (gpointer item, gpointer data)
+{
+  GtsTriangle * t = item;
+  GHashTable * ht = data;
+  tri_data_t * td;
+
+  g_assert (t);
+  g_assert (ht);
+  td = tri_data_new (t);
+  g_hash_table_insert (ht, t, td);
+  return 0;
+}
+
+static void free_map_entry (gpointer key, gpointer value, gpointer user_data)
+{
+  GtsTriangle * t = key;
+  tri_data_t * td = value;
+
+  (void) user_data;
+  g_assert (t);
+  g_assert (td);
+  g_assert (td->t == t);
+  tri_data_destroy (td);
+}
+
+static map_t * map_new (GtsSurface * s)
+{
+  map_t * map;
+
+  map = g_malloc (sizeof (map_t));
+  map->ht = g_hash_table_new (NULL, NULL);
+  gts_surface_foreach_face (s, create_map_entry, map->ht);
+  return map;
+}
+
+static void map_destroy (map_t * map)
+{
+  if (!map)
+    return;
+  g_hash_table_foreach (map->ht, free_map_entry, NULL);
+  g_hash_table_destroy (map->ht);
+  g_free (map);
+}
+
+static tri_data_t * map_lookup (const map_t * map, GtsTriangle * t)
+{
+  tri_data_t * td;
+
+  g_assert (map);
+  g_assert (map->ht);
+  g_assert (t);
+  td = g_hash_table_lookup (map->ht, t);
+  g_assert (td);
+  g_assert (td->t == t);
+  return td;
+}
+
+/* other helper functions */
+
+static GtsTriangle * find_min_neighbor (heap_t * heap, GtsTriangle * t)
+{
+  GtsTriangle * min_neighbor = NULL;
+  gdouble min_key = G_MAXDOUBLE;
+  tri_data_t * td;
+  GSList * li;
+
+  g_assert (heap);
+  g_assert (t);
+
+  td = map_lookup (heap->map, t);
+  for (li = td->neighbors; li != NULL; li = li->next) {
+    GtsTriangle * t2 = li->data;
+    tri_data_t * td2 = map_lookup (heap->map, t2);
+    gdouble k;
+    
+    g_assert (td2);
+    if (td2->used)
+      continue;
+    g_assert (td2->pos);
+    k = td2->pos->key;
+    if (k < min_key) {
+      min_key = k;
+      min_neighbor = t2;
+    }
+  }
+  return min_neighbor;
+}
+
+static GtsTriangle * find_neighbor_forward (heap_t * heap,
+					    GtsTriangle * t,
+					    GtsVertex ** v1,
+					    GtsVertex ** v2,
+					    GtsVertex ** v3,
+					    gboolean left_turn)
+{
+  GtsTriangle * neighbor = NULL;
+  tri_data_t * td;
+  GSList * li;
+
+  g_assert (heap);
+  g_assert (t);
+  g_assert (v1 && v2 && v3);
+  g_assert (vertices_are_unique (*v1, *v2, *v3));
+  
+  td = map_lookup (heap->map, t);
+  g_assert (td);
+  for (li = td->neighbors; li && !neighbor; li = li->next) {
+    GtsTriangle * t2 = li->data;
+    tri_data_t * td2 = map_lookup (heap->map, t2);
+    GtsVertex * v4, * v5, * v6;
+    
+    g_assert (td2);
+    if (t2 == t || td2->used)
+      continue;
+    gts_triangle_vertices (t2, &v4, &v5, &v6);
+    if (left_turn) {
+      if (!vertices_match (*v1, *v3, NULL, &v4, &v5, &v6))
+	continue;
+    } else {
+      if (!vertices_match (*v3, *v2, NULL, &v4, &v5, &v6))
+	continue;
+    }
+    neighbor = t2;
+    *v1 = v4;
+    *v2 = v5;
+    *v3 = v6;
+  }
+  return neighbor;
+}
+
+static GtsTriangle * find_neighbor_backward (heap_t * heap,
+					     GtsTriangle * t,
+					     GtsVertex ** v1,
+					     GtsVertex ** v2,
+					     GtsVertex ** v3,
+					     gboolean left_turn)
+{
+  GtsTriangle * neighbor = NULL;
+  tri_data_t * td;
+  GSList * li;
+
+  g_assert (heap);
+  g_assert (t);
+  g_assert (v1 && v2 && v3);
+  g_assert (vertices_are_unique (*v1, *v2, *v3));
+
+  td = map_lookup (heap->map, t);
+  g_assert (td);
+  for (li = td->neighbors; li && !neighbor; li = li->next) {
+    GtsTriangle * t2 = li->data;
+    tri_data_t * td2 = map_lookup (heap->map, t2);
+    GtsVertex * v4, * v5, * v6;
+    
+    g_assert (td2);
+    if (t2 == t || td2->used)
+      continue;
+    gts_triangle_vertices (t2, &v4, &v5, &v6);
+    if (left_turn) {
+      if (!vertices_match (NULL, *v2, *v1, &v4, &v5, &v6))
+	continue;
+    } else if (!vertices_match(*v1, NULL, *v2, &v4, &v5, &v6))
+      continue;
+    neighbor = t2;
+    *v1 = v4;
+    *v2 = v5;
+    *v3 = v6;
+  }
+  return neighbor;
+}
+
+static GSList * grow_strip_forward (heap_t * heap,
+				    GSList * strip,
+				    GtsTriangle * t,
+				    GtsVertex * v1,
+				    GtsVertex * v2,
+				    GtsVertex * v3)
+{
+  gboolean left_turn;
+  
+  g_assert (heap);
+  g_assert (g_slist_length(strip) == 2);
+  g_assert (t);
+  g_assert (v1 && v2 && v3);
+  g_assert (vertices_are_unique (v1, v2, v3));
+
+  left_turn = TRUE;
+  while ((t = find_neighbor_forward (heap, t, &v1, &v2, &v3, 
+				     left_turn)) != NULL) {
+    heap_remove (heap, t);
+    strip = g_slist_prepend (strip, t);
+    left_turn = !left_turn;
+  }
+  return strip;
+}
+
+static GSList * grow_strip_backward (heap_t * heap,
+				     GSList * strip,
+				     GtsTriangle * t,
+				     GtsVertex * v1,
+				     GtsVertex * v2,
+				     GtsVertex * v3)
+{
+  /* we have to make sure we add an even number of triangles */
+  GtsTriangle * t2;
+
+  g_assert (heap);
+  g_assert (g_slist_length(strip) >= 2);
+  g_assert (t);
+  g_assert (v1 && v2 && v3);
+  g_assert (vertices_are_unique (v1, v2, v3));
+
+  while ((t2 = find_neighbor_backward (heap, t, &v1, &v2, &v3,
+				       FALSE)) != NULL
+	 && (t = find_neighbor_backward (heap, t2, &v1, &v2, &v3,
+					 TRUE)) != NULL) {
+    heap_remove (heap, t2);
+    heap_remove (heap, t);
+    strip = g_slist_prepend (strip, t2);
+    strip = g_slist_prepend (strip, t);
+  }
+  return strip;
+}
+
+static gboolean find_right_turn (GtsVertex ** v1,
+				 GtsVertex ** v2,
+				 GtsVertex ** v3,
+				 GtsVertex ** v4,
+				 GtsVertex ** v5,
+				 GtsVertex ** v6)
+{
+  GtsVertex * v;
+
+  g_assert (v1 && v2 && v3);
+  g_assert (v4 && v5 && v6);
+  g_assert (vertices_are_unique (*v1, *v2, *v3));
+  g_assert (vertices_are_unique (*v4, *v5, *v6));
+  g_assert (num_shared_vertices (*v1, *v2, *v3, *v4, *v5, *v6) == 2);
+
+  v = non_shared_vertex1 (*v1, *v2, *v3, *v4, *v5, *v6);
+  match_vertex (v, v1, v2, v3);
+  match_vertex (*v3, v4, v5, v6);
+
+  g_assert (v1 && v2 && v3);
+  g_assert (v4 && v5 && v6);
+  g_assert (*v4 == *v3);
+
+  if (*v5 == *v2) {
+    g_assert (vertices_are_unique (*v1, *v2, *v3));
+    g_assert (vertices_are_unique (*v4, *v5, *v6));
+    g_assert (num_shared_vertices (*v1, *v2, *v3,
+					*v4, *v5, *v6) == 2);
+    return TRUE;
+  } else {
+#ifdef DEBUG
+    g_warning ("couldn't find a right turn");
+#endif /* DEBUG */
+    return FALSE;
+  }
+}
+
+/**
+ * gts_surface_strip:
+ * @s: a #GtsSurface.
+ *
+ * Decompose @s into triangle strips for fast-rendering.
+ *
+ * Returns: a list of triangle strips containing all the triangles of @s. 
+ * A triangle strip is itself a list of successive triangles having one edge
+ * in common.
+ */
+GSList * gts_surface_strip (GtsSurface *s)
+{
+  GSList * strips = NULL;
+  heap_t * heap;
+
+  g_return_val_if_fail (s != NULL, NULL);
+
+  heap = heap_new (s);
+  while (!heap_is_empty (heap)) {
+    GtsTriangle * t1, * t2;
+    GtsVertex * v1, * v2, * v3, * v4, * v5, * v6;
+    GSList * strip = NULL;
+
+    /* remove heap top */
+    t1 = heap_top (heap);
+    g_assert (t1);
+    heap_remove (heap, t1);
+
+    /* start a new strip */
+    strip = g_slist_prepend (strip, t1);
+
+    /* find second triangle */
+    t2 = find_min_neighbor (heap, t1);
+    if (t2) {
+      g_assert (t2 != t1);
+
+      /* find right turn */
+      gts_triangle_vertices (t1, &v1, &v2, &v3);
+      gts_triangle_vertices (t2, &v4, &v5, &v6);
+      if (find_right_turn (&v1, &v2, &v3, &v4, &v5, &v6)) {
+	heap_remove (heap, t2);
+	strip = g_slist_prepend (strip, t2);
+
+	/* grow strip forward */
+	strip = grow_strip_forward (heap, strip, t2, v4, v5, v6);
+
+	strip = g_slist_reverse (strip);
+
+	/* grow strip backward */
+	strip = grow_strip_backward (heap, strip, t1, v1, v2, v3);
+      }
+    }
+    strips = g_slist_prepend (strips, strip);
+  }
+  strips = g_slist_reverse (strips);
+  heap_destroy (heap);
+
+  return strips;
+}
diff --git a/gts/surface.c b/gts/surface.c
new file mode 100644
index 0000000..34c5cbe
--- /dev/null
+++ b/gts/surface.c
@@ -0,0 +1,2743 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <stdlib.h>
+#include <math.h>
+#include <string.h>
+#include "gts.h"
+
+#include "gts-private.h"
+
+static void destroy_foreach_face (GtsFace * f, GtsSurface * s)
+{
+  f->surfaces = g_slist_remove (f->surfaces, s);
+  if (!GTS_OBJECT_DESTROYED (f) &&
+      !gts_allow_floating_faces && f->surfaces == NULL)
+    gts_object_destroy (GTS_OBJECT (f));
+}
+
+static void surface_destroy (GtsObject * object)
+{
+  GtsSurface * surface = GTS_SURFACE (object);
+  
+  gts_surface_foreach_face (surface, (GtsFunc) destroy_foreach_face, surface);
+#ifdef USE_SURFACE_BTREE
+  g_tree_destroy (surface->faces);
+#else /* not USE_SURFACE_BTREE */
+  g_hash_table_destroy (surface->faces);
+#endif /* not USE_SURFACE_BTREE */
+
+  (* GTS_OBJECT_CLASS (gts_surface_class ())->parent_class->destroy) (object);
+}
+
+static void surface_write (GtsObject * object, FILE * fptr)
+{
+  fprintf (fptr, " %s %s %s %s", 
+	   object->klass->info.name,
+	   GTS_OBJECT_CLASS (GTS_SURFACE (object)->face_class)->info.name,
+	   GTS_OBJECT_CLASS (GTS_SURFACE (object)->edge_class)->info.name,
+	   GTS_POINT_CLASS (GTS_SURFACE (object)->vertex_class)->binary ?
+	   "GtsVertexBinary" :
+	   GTS_OBJECT_CLASS (GTS_SURFACE (object)->vertex_class)->info.name);
+}
+
+static void surface_class_init (GtsSurfaceClass * klass)
+{
+  GTS_OBJECT_CLASS (klass)->destroy = surface_destroy;
+  GTS_OBJECT_CLASS (klass)->write = surface_write;
+  klass->add_face = NULL;
+  klass->remove_face = NULL;
+}
+
+#ifdef USE_SURFACE_BTREE
+static gint compare_pointers (gconstpointer a, gconstpointer b)
+{
+  if (GPOINTER_TO_UINT (a) < GPOINTER_TO_UINT (b))
+    return -1;
+  if (GPOINTER_TO_UINT (a) > GPOINTER_TO_UINT (b))
+    return 1;
+  return 0;
+}
+#endif /* USE_SURFACE_BTREE */
+
+static void surface_init (GtsSurface * surface)
+{
+#ifdef USE_SURFACE_BTREE
+  surface->faces = g_tree_new (compare_pointers);
+#else /* not USE_SURFACE_BTREE */
+  surface->faces = g_hash_table_new (NULL, NULL);
+#endif /* not USE_SURFACE_BTREE */
+  surface->vertex_class = gts_vertex_class ();
+  surface->edge_class = gts_edge_class ();
+  surface->face_class = gts_face_class ();
+  surface->keep_faces = FALSE;
+}
+
+/**
+ * gts_surface_class:
+ *
+ * Returns: the #GtsSurfaceClass.
+ */
+GtsSurfaceClass * gts_surface_class (void)
+{
+  static GtsSurfaceClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo surface_info = {
+      "GtsSurface",
+      sizeof (GtsSurface),
+      sizeof (GtsSurfaceClass),
+      (GtsObjectClassInitFunc) surface_class_init,
+      (GtsObjectInitFunc) surface_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (gts_object_class (), &surface_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_surface_new:
+ * @klass: a #GtsSurfaceClass.
+ * @face_class: a #GtsFaceClass.
+ * @edge_class: a #GtsEdgeClass.
+ * @vertex_class: a #GtsVertexClass.
+ *
+ * Returns: a new empty #GtsSurface.
+ */
+GtsSurface * gts_surface_new (GtsSurfaceClass * klass,
+			      GtsFaceClass * face_class,
+			      GtsEdgeClass * edge_class,
+			      GtsVertexClass * vertex_class)
+{
+  GtsSurface * s;
+
+  s = GTS_SURFACE (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  s->vertex_class = vertex_class;
+  s->edge_class = edge_class;
+  s->face_class = face_class;
+
+  return s;
+}
+
+/**
+ * gts_surface_add_face:
+ * @s: a #GtsSurface.
+ * @f: a #GtsFace.
+ *
+ * Adds face @f to surface @s.
+ */
+void gts_surface_add_face (GtsSurface * s, GtsFace * f)
+{
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (f != NULL);
+
+  g_assert (s->keep_faces == FALSE);
+
+#ifdef USE_SURFACE_BTREE
+  if (!g_tree_lookup (s->faces, f)) {
+    f->surfaces = g_slist_prepend (f->surfaces, s);
+    g_tree_insert (s->faces, f, f);
+  }
+#else /* not USE_SURFACE_BTREE */
+  if (!g_hash_table_lookup (s->faces, f)) {
+    f->surfaces = g_slist_prepend (f->surfaces, s);
+    g_hash_table_insert (s->faces, f, f);
+  }
+#endif /* not USE_SURFACE_BTREE */
+
+  if (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->add_face)
+    (* GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->add_face) (s, f);
+}
+
+/**
+ * gts_surface_remove_face:
+ * @s: a #GtsSurface.
+ * @f: a #GtsFace.
+ *
+ * Removes face @f from surface @s.
+ */
+void gts_surface_remove_face (GtsSurface * s, 
+			      GtsFace * f)
+{
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (f != NULL);
+
+  g_assert (s->keep_faces == FALSE);
+
+#ifdef USE_SURFACE_BTREE
+  g_tree_remove (s->faces, f);
+#else /* not USE_SURFACE_BTREE */
+  g_hash_table_remove (s->faces, f);
+#endif /* not USE_SURFACE_BTREE */
+
+  f->surfaces = g_slist_remove (f->surfaces, s);
+
+  if (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->remove_face)
+    (* GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->remove_face) (s, f);
+
+  if (!GTS_OBJECT_DESTROYED (f) &&
+      !gts_allow_floating_faces && 
+      f->surfaces == NULL)
+    gts_object_destroy (GTS_OBJECT (f));
+}
+
+/**
+ * gts_surface_read:
+ * @surface: a #GtsSurface.
+ * @f: a #GtsFile.
+ *
+ * Add to @surface the data read from @f. The format of the file pointed to
+ * by @f is as described in gts_surface_write().
+ *
+ * Returns: 0 if successful or the line number at which the parsing
+ * stopped in case of error (in which case the @error field of @f is
+ * set to a description of the error which occured).  
+ */
+/* Update split.c/surface_read() if modifying this function */
+guint gts_surface_read (GtsSurface * surface, GtsFile * f)
+{
+  GtsVertex ** vertices;
+  GtsEdge ** edges;
+  guint n, nv, ne, nf;
+
+  g_return_val_if_fail (surface != NULL, 1);
+  g_return_val_if_fail (f != NULL, 1);
+
+  if (f->type != GTS_INT) {
+    gts_file_error (f, "expecting an integer (number of vertices)");
+    return f->line;
+  }
+  nv = atoi (f->token->str);
+
+  gts_file_next_token (f);
+  if (f->type != GTS_INT) {
+    gts_file_error (f, "expecting an integer (number of edges)");
+    return f->line;
+  }
+  ne = atoi (f->token->str);
+
+  gts_file_next_token (f);
+  if (f->type != GTS_INT) {
+    gts_file_error (f, "expecting an integer (number of faces)");
+    return f->line;
+  }
+  nf = atoi (f->token->str);
+  
+  gts_file_next_token (f);
+  if (f->type == GTS_STRING) {
+    if (f->type != GTS_STRING) {
+      gts_file_error (f, "expecting a string (GtsSurfaceClass)");
+      return f->line;
+    }
+    gts_file_next_token (f);
+    if (f->type != GTS_STRING) {
+      gts_file_error (f, "expecting a string (GtsFaceClass)");
+      return f->line;
+    }
+    gts_file_next_token (f);
+    if (f->type != GTS_STRING) {
+      gts_file_error (f, "expecting a string (GtsEdgeClass)");
+      return f->line;
+    }
+    gts_file_next_token (f);
+    if (f->type != GTS_STRING) {
+      gts_file_error (f, "expecting a string (GtsVertexClass)");
+      return f->line;
+    }
+    if (!strcmp (f->token->str, "GtsVertexBinary"))
+      GTS_POINT_CLASS (surface->vertex_class)->binary = TRUE;
+    else {
+      GTS_POINT_CLASS (surface->vertex_class)->binary = FALSE;
+      gts_file_first_token_after (f, '\n');
+    }
+  }
+  else
+    gts_file_first_token_after (f, '\n');
+
+  if (nf <= 0)
+    return 0;
+
+  /* allocate nv + 1 just in case nv == 0 */
+  vertices = g_malloc ((nv + 1)*sizeof (GtsVertex *));
+  edges = g_malloc ((ne + 1)*sizeof (GtsEdge *));
+  
+  n = 0;
+  while (n < nv && f->type != GTS_ERROR) {
+    GtsObject * new_vertex =
+      gts_object_new (GTS_OBJECT_CLASS (surface->vertex_class));
+
+    (* GTS_OBJECT_CLASS (surface->vertex_class)->read) (&new_vertex, f);
+    if (f->type != GTS_ERROR) {
+      if (!GTS_POINT_CLASS (surface->vertex_class)->binary)
+	gts_file_first_token_after (f, '\n');
+      vertices[n++] = GTS_VERTEX (new_vertex);
+    }
+    else
+      gts_object_destroy (new_vertex);
+  }
+  if (f->type == GTS_ERROR)
+    nv = n;
+  if (GTS_POINT_CLASS (surface->vertex_class)->binary)
+    gts_file_first_token_after (f, '\n');
+
+  n = 0;
+  while (n < ne && f->type != GTS_ERROR) {
+    guint p1, p2;
+
+    if (f->type != GTS_INT)
+      gts_file_error (f, "expecting an integer (first vertex index)");
+    else {
+      p1 = atoi (f->token->str);
+      if (p1 == 0 || p1 > nv)
+	gts_file_error (f, "vertex index `%d' is out of range `[1,%d]'", 
+			p1, nv);
+      else {
+	gts_file_next_token (f);
+	if (f->type != GTS_INT)
+	  gts_file_error (f, "expecting an integer (second vertex index)");
+	else {
+	  p2 = atoi (f->token->str);
+	  if (p2 == 0 || p2 > nv)
+	    gts_file_error (f, "vertex index `%d' is out of range `[1,%d]'", 
+			    p2, nv);
+	  else {
+	    GtsEdge * new_edge =
+	      gts_edge_new (surface->edge_class,
+			    vertices[p1 - 1], vertices[p2 - 1]);
+
+	    gts_file_next_token (f);
+	    if (f->type != '\n')
+	      if (GTS_OBJECT_CLASS (surface->edge_class)->read)
+		(*GTS_OBJECT_CLASS (surface->edge_class)->read)
+		  ((GtsObject **) &new_edge, f);
+	    gts_file_first_token_after (f, '\n');
+	    edges[n++] = new_edge;
+	  }
+	}
+      }
+    }
+  }
+  if (f->type == GTS_ERROR)
+    ne = n;
+
+  n = 0;
+  while (n < nf && f->type != GTS_ERROR) {
+    guint s1, s2, s3;
+
+    if (f->type != GTS_INT)
+      gts_file_error (f, "expecting an integer (first edge index)");
+    else {
+      s1 = atoi (f->token->str);
+      if (s1 == 0 || s1 > ne)
+	gts_file_error (f, "edge index `%d' is out of range `[1,%d]'", 
+			s1, ne);
+      else {
+	gts_file_next_token (f);
+	if (f->type != GTS_INT)
+	  gts_file_error (f, "expecting an integer (second edge index)");
+	else {
+	  s2 = atoi (f->token->str);
+	  if (s2 == 0 || s2 > ne)
+	    gts_file_error (f, "edge index `%d' is out of range `[1,%d]'", 
+			    s2, ne);
+	  else {
+	    gts_file_next_token (f);
+	    if (f->type != GTS_INT)
+	      gts_file_error (f, "expecting an integer (third edge index)");
+	    else {
+	      s3 = atoi (f->token->str);
+	      if (s3 == 0 || s3 > ne)
+		gts_file_error (f, "edge index `%d' is out of range `[1,%d]'", 
+				s3, ne);
+	      else {
+		GtsFace * new_face = gts_face_new (surface->face_class,
+						   edges[s1 - 1],
+						   edges[s2 - 1],
+						   edges[s3 - 1]);
+
+		gts_file_next_token (f);
+		if (f->type != '\n')
+		  if (GTS_OBJECT_CLASS (surface->face_class)->read)
+		    (*GTS_OBJECT_CLASS (surface->face_class)->read)
+		      ((GtsObject **) &new_face, f);
+		gts_file_first_token_after (f, '\n');
+		gts_surface_add_face (surface, new_face);
+		n++;
+	      }
+	    }
+	  }
+	}
+      }
+    }
+  }
+
+  if (f->type == GTS_ERROR) {
+    gts_allow_floating_vertices = TRUE;
+    while (nv)
+      gts_object_destroy (GTS_OBJECT (vertices[nv-- - 1]));
+    gts_allow_floating_vertices = FALSE;
+  }
+
+  g_free (vertices);
+  g_free (edges);
+
+  if (f->type == GTS_ERROR)
+    return f->line;
+  return 0;
+}
+
+static void sum_area (GtsFace * f, gdouble * area) {
+  *area += gts_triangle_area (GTS_TRIANGLE (f));
+}
+
+/**
+ * gts_surface_area:
+ * @s: a #GtsSurface.
+ *
+ * Returns: the area of @s obtained as the sum of the signed areas of its
+ * faces.
+ */
+gdouble gts_surface_area (GtsSurface * s)
+{  
+  gdouble area = 0.0;
+  gts_surface_foreach_face (s, (GtsFunc)sum_area, &area);
+  return area;
+}
+
+/**
+ * gts_range_init:
+ * @r: a #GtsRange.
+ *
+ * Initializes a #GtsRange.
+ */
+void gts_range_init (GtsRange * r)
+{
+  g_return_if_fail (r != NULL);
+
+  r->max = - G_MAXDOUBLE;
+  r->min = G_MAXDOUBLE;
+  r->sum = r->sum2 = 0.0;
+  r->n = 0;
+}
+
+/**
+ * gts_range_reset:
+ * @r: a #GtsRange.
+ *
+ * Sets all the fields of @r to 0.
+ */
+void gts_range_reset (GtsRange * r)
+{
+  g_return_if_fail (r != NULL);
+
+  r->max = 0.0;
+  r->min = 0.0;
+  r->sum = r->sum2 = 0.0;
+  r->n = 0;
+}
+
+/**
+ * gts_range_add_value:
+ * @r: a #GtsRange.
+ * @val: a value to add to @r.
+ *
+ * Adds @val to @r.
+ */
+void gts_range_add_value (GtsRange * r, gdouble val)
+{
+  g_return_if_fail (r != NULL);
+
+  if (val < r->min) r->min = val;
+  if (val > r->max) r->max = val;
+  r->sum += val;
+  r->sum2 += val*val;
+  r->n++;
+}
+
+/**
+ * gts_range_update:
+ * @r: a #GtsRange.
+ * 
+ * Updates the fields of @r.
+ */
+void gts_range_update (GtsRange * r)
+{
+  g_return_if_fail (r != NULL);
+
+  if (r->n > 0) {
+    if (r->sum2 - r->sum*r->sum/(gdouble) r->n >= 0.)
+      r->stddev = sqrt ((r->sum2 - r->sum*r->sum/(gdouble) r->n)
+			/(gdouble) r->n);
+    else
+      r->stddev = 0.;
+    r->mean = r->sum/(gdouble) r->n;
+  }
+  else 
+    r->min = r->max = r->mean = r->stddev = 0.;
+}
+
+/**
+ * gts_range_print:
+ * @r: a #GtsRange.
+ * @fptr: a file pointer.
+ * 
+ * Writes a text representation of @r in @fptr.
+ */
+void gts_range_print (GtsRange * r, FILE * fptr)
+{
+  g_return_if_fail (r != NULL);
+  g_return_if_fail (fptr != NULL);
+  fprintf (fptr, "min: %g mean: %g | %g max: %g", 
+	   r->min, r->mean, r->stddev, r->max);
+}
+
+static void stats_foreach_vertex (GtsVertex * v, GtsSurfaceStats * stats) 
+{
+  GSList * i = v->segments;
+  guint nedges = 0;
+
+  while (i) {
+    if (GTS_IS_EDGE (i->data) && 
+	gts_edge_has_parent_surface (i->data, stats->parent))
+      nedges++;
+    i = i->next;
+  }
+  gts_range_add_value (&stats->edges_per_vertex, nedges);
+}
+
+static void stats_foreach_edge (GtsEdge * e, GtsSurfaceStats * stats) 
+{
+  guint nt = gts_edge_face_number (e, stats->parent);
+
+  if (gts_segment_is_duplicate (GTS_SEGMENT (e)))
+    stats->n_duplicate_edges++;
+  if (nt == 1)
+    stats->n_boundary_edges++;
+  else if (nt > 2)
+    stats->n_non_manifold_edges++;
+  gts_range_add_value (&stats->faces_per_edge, nt);
+}
+
+static void stats_foreach_face (GtsTriangle * t, GtsSurfaceStats * stats)
+{
+  if (!gts_face_is_compatible (GTS_FACE (t), stats->parent))
+    stats->n_incompatible_faces++;
+  if (gts_triangle_is_duplicate (t))
+    stats->n_duplicate_faces++;
+  stats->n_faces++;
+}
+
+/**
+ * gts_surface_stats:
+ * @s: a #GtsSurface.
+ * @stats: a #GtsSurfaceStats.
+ *
+ * Fills @stats with the statistics relevant to surface @s.
+ */
+void gts_surface_stats (GtsSurface * s, GtsSurfaceStats * stats)
+{
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (stats != NULL);
+
+  stats->parent = s;
+  stats->n_faces = 0;
+  stats->n_incompatible_faces = 0;
+  stats->n_duplicate_faces = 0;
+  stats->n_duplicate_edges = 0;
+  stats->n_boundary_edges = 0;
+  stats->n_non_manifold_edges = 0;
+  gts_range_init (&stats->edges_per_vertex);
+  gts_range_init (&stats->faces_per_edge);
+
+  gts_surface_foreach_vertex (s, (GtsFunc) stats_foreach_vertex, stats);
+  gts_surface_foreach_edge (s, (GtsFunc) stats_foreach_edge, stats);
+  gts_surface_foreach_face (s, (GtsFunc) stats_foreach_face, stats);
+
+  gts_range_update (&stats->edges_per_vertex);
+  gts_range_update (&stats->faces_per_edge);
+}
+
+static void quality_foreach_edge (GtsSegment * s,
+				  GtsSurfaceQualityStats * stats) 
+{
+  GSList * i = GTS_EDGE (s)->triangles;
+
+  gts_range_add_value (&stats->edge_length, 
+		   gts_point_distance (GTS_POINT (s->v1), 
+				       GTS_POINT (s->v2)));
+  while (i) {
+    GSList * j = i->next;
+    while (j) {
+      gts_range_add_value (&stats->edge_angle,
+			   fabs (gts_triangles_angle (i->data, j->data)));
+      j = j->next;
+    }
+    i = i->next;
+  }
+}
+
+static void quality_foreach_face (GtsTriangle * t,
+				  GtsSurfaceQualityStats * stats) 
+{
+  gts_range_add_value (&stats->face_quality, gts_triangle_quality (t));
+  gts_range_add_value (&stats->face_area, gts_triangle_area (t));
+}
+
+/**
+ * gts_surface_quality_stats:
+ * @s: a #GtsSurface.
+ * @stats: a #GtsSurfaceQualityStats.
+ *
+ * Fills @stats with quality statistics relevant to surface @s.
+ */
+void gts_surface_quality_stats (GtsSurface * s, GtsSurfaceQualityStats * stats)
+{
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (stats != NULL);
+
+  stats->parent = s;
+  gts_range_init (&stats->face_quality);
+  gts_range_init (&stats->face_area);
+  gts_range_init (&stats->edge_length);
+  gts_range_init (&stats->edge_angle);
+
+  gts_surface_foreach_edge (s, (GtsFunc) quality_foreach_edge, stats);  
+  gts_surface_foreach_face (s, (GtsFunc) quality_foreach_face, stats);
+
+  gts_range_update (&stats->face_quality);
+  gts_range_update (&stats->face_area);
+  gts_range_update (&stats->edge_length);
+  gts_range_update (&stats->edge_angle);
+}
+
+/**
+ * gts_surface_print_stats:
+ * @s: a #GtsSurface.
+ * @fptr: a file pointer.
+ *
+ * Writes in the file pointed to by @fptr the statistics for surface @s.
+ */
+void gts_surface_print_stats (GtsSurface * s, FILE * fptr)
+{
+  GtsSurfaceStats stats;
+  GtsSurfaceQualityStats qstats;
+
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (fptr != NULL);
+
+  gts_surface_stats (s, &stats);
+  gts_surface_quality_stats (s, &qstats);
+
+  fprintf (fptr, 
+	   "# vertices: %u edges: %u faces: %u\n"
+	   "# Connectivity statistics\n"
+	   "#   incompatible faces: %u\n"
+	   "#   duplicate faces: %u\n"
+	   "#   boundary edges: %u\n"
+	   "#   duplicate edges: %u\n"
+	   "#   non-manifold edges: %u\n",
+	   stats.edges_per_vertex.n, 
+	   stats.faces_per_edge.n,
+	   stats.n_faces,
+	   stats.n_incompatible_faces,
+	   stats.n_duplicate_faces,
+	   stats.n_boundary_edges,
+	   stats.n_duplicate_edges,
+	   stats.n_non_manifold_edges);
+  fputs ("#   edges per vertex: ", fptr); 
+  gts_range_print (&stats.edges_per_vertex, fptr);
+  fputs ("\n#   faces per edge: ", fptr);
+  gts_range_print (&stats.faces_per_edge, fptr);
+  fputs ("\n# Geometric statistics\n#   face quality: ", fptr);
+  gts_range_print (&qstats.face_quality, fptr);
+  fputs ("\n#   face area  : ", fptr);
+  gts_range_print (&qstats.face_area, fptr);
+  fputs ("\n#   edge length : ", fptr);
+  gts_range_print (&qstats.edge_length, fptr);
+  fputc ('\n', fptr);
+}
+
+static void write_vertex (GtsPoint * p, gpointer * data)
+{
+  (*GTS_OBJECT (p)->klass->write) (GTS_OBJECT (p), (FILE *) data[0]);
+  if (!GTS_POINT_CLASS (GTS_OBJECT (p)->klass)->binary)
+    fputc ('\n', (FILE *) data[0]);
+  g_hash_table_insert (data[2], p, 
+		       GUINT_TO_POINTER (++(*((guint *) data[1]))));
+}
+
+static void write_edge (GtsSegment * s, gpointer * data) 
+{
+  fprintf ((FILE *) data[0], "%u %u",
+	   GPOINTER_TO_UINT (g_hash_table_lookup (data[2], s->v1)),
+	   GPOINTER_TO_UINT (g_hash_table_lookup (data[2], s->v2)));
+  if (GTS_OBJECT (s)->klass->write)
+    (*GTS_OBJECT (s)->klass->write) (GTS_OBJECT (s), (FILE *) data[0]);
+  fputc ('\n', (FILE *) data[0]);
+  g_hash_table_insert (data[3], s, 
+		       GUINT_TO_POINTER (++(*((guint *) data[1]))));
+}
+
+static void write_face (GtsTriangle * t, gpointer * data)
+{
+  fprintf (data[0], "%u %u %u",
+	   GPOINTER_TO_UINT (g_hash_table_lookup (data[3], t->e1)),
+	   GPOINTER_TO_UINT (g_hash_table_lookup (data[3], t->e2)),
+	   GPOINTER_TO_UINT (g_hash_table_lookup (data[3], t->e3)));
+  if (GTS_OBJECT (t)->klass->write)
+    (*GTS_OBJECT (t)->klass->write) (GTS_OBJECT (t), data[0]);
+  fputc ('\n', data[0]);
+}
+
+/**
+ * gts_surface_write:
+ * @s: a #GtsSurface.
+ * @fptr: a file pointer.
+ * 
+ * Writes in the file @fptr an ASCII representation of @s. The file
+ * format is as follows. 
+ *
+ * All the lines beginning with #GTS_COMMENTS are ignored. The first line
+ * contains three unsigned integers separated by spaces. The first
+ * integer is the number of vertices, nv, the second is the number of
+ * edges, ne and the third is the number of faces, nf.
+ *
+ * Follows nv lines containing the x, y and z coordinates of the
+ * vertices.  Follows ne lines containing the two indices (starting
+ * from one) of the vertices of each edge. Follows nf lines containing
+ * the three ordered indices (also starting from one) of the edges of
+ * each face.  
+ *
+ * The format described above is the least common denominator to all
+ * GTS files.  Consistent with an object-oriented approach, the GTS
+ * file format is extensible. Each of the lines of the file can be
+ * extended with user-specific attributes accessible through the
+ * read() and write() virtual methods of each of the objects written
+ * (surface, vertices, edges or faces). When read with different
+ * object classes, these extra attributes are just ignored.  
+ */
+void gts_surface_write (GtsSurface * s, FILE * fptr)
+{
+  guint n;
+  gpointer data[4];
+  GHashTable * vindex, * eindex;
+  GtsSurfaceStats stats;
+
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (fptr != NULL);
+
+  data[0] = fptr;
+  data[1] = &n;
+  data[2] = vindex = g_hash_table_new (NULL, NULL);
+  data[3] = eindex = g_hash_table_new (NULL, NULL);
+
+  gts_surface_stats (s, &stats);
+  fprintf (fptr, "%u %u %u", 
+	   stats.edges_per_vertex.n, 
+	   stats.faces_per_edge.n, 
+	   stats.n_faces);
+  if (GTS_OBJECT (s)->klass->write)
+    (*GTS_OBJECT (s)->klass->write) (GTS_OBJECT (s), fptr);
+  fputc ('\n', fptr);
+  n = 0;
+  gts_surface_foreach_vertex (s, (GtsFunc) write_vertex, data);
+  n = 0;
+  if (GTS_POINT_CLASS (s->vertex_class)->binary)
+    fputc ('\n', fptr);
+  gts_surface_foreach_edge (s, (GtsFunc) write_edge, data);
+  gts_surface_foreach_face (s, (GtsFunc) write_face, data);
+  g_hash_table_destroy (vindex);
+  g_hash_table_destroy (eindex);
+}
+
+static void write_vertex_oogl (GtsPoint * p, gpointer * data)
+{
+  FILE * fp = data[0];
+
+  fprintf (fp, "%g %g %g", p->x, p->y, p->z);
+  if (GTS_OBJECT (p)->klass->color) {
+    GtsColor c = (* GTS_OBJECT (p)->klass->color) (GTS_OBJECT (p));
+    fprintf (fp, " %g %g %g 1.0\n", c.r, c.g, c.b);
+  }
+  else
+    fputc ('\n', fp);
+  GTS_OBJECT (p)->reserved = GUINT_TO_POINTER ((*((guint *) data[1]))++);
+}
+
+static void write_face_oogl (GtsTriangle * t, FILE * fp)
+{
+  GtsVertex * v1, * v2, * v3;
+  gts_triangle_vertices (t, &v1, &v2, &v3);
+  fprintf (fp, "3 %u %u %u",
+	   GPOINTER_TO_UINT (GTS_OBJECT (v1)->reserved),
+	   GPOINTER_TO_UINT (GTS_OBJECT (v2)->reserved),
+	   GPOINTER_TO_UINT (GTS_OBJECT (v3)->reserved));
+  if (GTS_OBJECT (t)->klass->color) {
+    GtsColor c = (* GTS_OBJECT (t)->klass->color) (GTS_OBJECT (t));
+    fprintf (fp, " %g %g %g\n", c.r, c.g, c.b);
+  }
+  else
+    fputc ('\n', fp);
+}
+
+/**
+ * gts_surface_write_oogl:
+ * @s: a #GtsSurface.
+ * @fptr: a file pointer.
+ * 
+ * Writes in the file @fptr an OOGL (Geomview) representation of @s.
+ */
+void gts_surface_write_oogl (GtsSurface * s, FILE * fptr)
+{
+  guint n = 0;
+  gpointer data[2];
+  GtsSurfaceStats stats;
+
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (fptr != NULL);
+
+  data[0] = fptr;
+  data[1] = &n;
+
+  gts_surface_stats (s, &stats);
+  if (GTS_OBJECT_CLASS (s->vertex_class)->color)
+    fputs ("COFF ", fptr);
+  else
+    fputs ("OFF ", fptr);
+  fprintf (fptr, "%u %u %u\n", 
+	   stats.edges_per_vertex.n, 
+	   stats.n_faces,
+	   stats.faces_per_edge.n);
+  gts_surface_foreach_vertex (s, (GtsFunc) write_vertex_oogl, data);
+  gts_surface_foreach_face (s, (GtsFunc) write_face_oogl, fptr);
+  gts_surface_foreach_vertex (s, (GtsFunc) gts_object_reset_reserved, NULL);
+}
+
+static void write_vertex_vtk (GtsPoint * p, gpointer * data)
+{
+  FILE * fp = data[0];
+
+  fprintf (fp, "%g %g %g\n", p->x, p->y, p->z);
+  GTS_OBJECT (p)->reserved = GUINT_TO_POINTER ((*((guint *) data[1]))++);
+}
+
+static void write_face_vtk (GtsTriangle * t, FILE * fp)
+{
+  GtsVertex * v1, * v2, * v3;
+  gts_triangle_vertices (t, &v1, &v2, &v3);
+  fprintf (fp, "3 %u %u %u\n",
+	   GPOINTER_TO_UINT (GTS_OBJECT (v1)->reserved),
+	   GPOINTER_TO_UINT (GTS_OBJECT (v2)->reserved),
+	   GPOINTER_TO_UINT (GTS_OBJECT (v3)->reserved));
+}
+
+/**
+ * gts_surface_write_vtk:
+ * @s: a #GtsSurface.
+ * @fptr: a file pointer.
+ * 
+ * Writes in the file @fptr a VTK representation of @s.
+ */
+void gts_surface_write_vtk (GtsSurface * s, FILE * fptr)
+{
+  guint n = 0;
+  gpointer data[2];
+  GtsSurfaceStats stats;
+
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (fptr != NULL);
+
+  data[0] = fptr;
+  data[1] = &n;
+
+  gts_surface_stats (s, &stats);
+  fprintf (fptr,
+	   "# vtk DataFile Version 2.0\n"
+	   "Generated by GTS\n"
+           "ASCII\n"
+	   "DATASET POLYDATA\n"
+	   "POINTS %u float\n",
+	   stats.edges_per_vertex.n);
+  gts_surface_foreach_vertex (s, (GtsFunc) write_vertex_vtk, data);
+  fprintf (fptr,
+	   "POLYGONS %u %u\n",
+	   stats.n_faces, stats.n_faces*4);
+  gts_surface_foreach_face (s, (GtsFunc) write_face_vtk, fptr);
+  gts_surface_foreach_vertex (s, (GtsFunc) gts_object_reset_reserved, NULL);  
+}
+
+static void write_edge_oogl_boundary (GtsSegment * s, gpointer * data)
+{
+  if (!gts_edge_is_boundary (GTS_EDGE (s), data[1]))
+    return;
+
+  if (GTS_OBJECT (s)->klass->color) {
+    GtsColor c = (* GTS_OBJECT (s)->klass->color) (GTS_OBJECT (s));
+    fprintf (data[0], "VECT 1 2 1 2 1 %g %g %g %g %g %g %g %g %g 1.\n",
+	     GTS_POINT (s->v1)->x, GTS_POINT (s->v1)->y, GTS_POINT (s->v1)->z,
+	     GTS_POINT (s->v2)->x, GTS_POINT (s->v2)->y, GTS_POINT (s->v2)->z,
+	     c.r, c.g, c.b);
+  }
+  else
+    fprintf (data[0], "VECT 1 2 0 2 0 %g %g %g %g %g %g\n",
+	     GTS_POINT (s->v1)->x, GTS_POINT (s->v1)->y, GTS_POINT (s->v1)->z,
+	     GTS_POINT (s->v2)->x, GTS_POINT (s->v2)->y, GTS_POINT (s->v2)->z);
+}
+
+/**
+ * gts_surface_write_oogl_boundary:
+ * @s: a #GtsSurface.
+ * @fptr: a file pointer.
+ * 
+ * Writes in the file @fptr an OOGL (Geomview) representation of the
+ * boundary of @s.  
+ */
+void gts_surface_write_oogl_boundary (GtsSurface * s, FILE * fptr)
+{
+  gpointer data[2];
+
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (fptr != NULL);
+
+  data[0] = fptr;
+  data[1] = s;
+  fputs ("LIST {\n", fptr);
+  gts_surface_foreach_edge (s, (GtsFunc) write_edge_oogl_boundary, data);
+  fputs ("}\n", fptr);
+}
+
+#ifdef USE_SURFACE_BTREE
+static gint vertex_foreach_face (GtsTriangle * t,
+				 gpointer t_data,
+				 gpointer * info)
+#else /* not USE_SURFACE_BTREE */
+static void vertex_foreach_face (GtsTriangle * t,
+				 gpointer t_data,
+				 gpointer * info)
+#endif /* not USE_SURFACE_BTREE */
+{
+  GHashTable * hash = info[0];
+  gpointer data = info[1];
+  GtsFunc func = (GtsFunc) info[2];
+  GtsSegment 
+    * s1 = GTS_SEGMENT (t->e1);
+
+  if (!g_hash_table_lookup (hash, s1->v1)) {
+    (*func) (s1->v1, data);
+    g_hash_table_insert (hash, s1->v1, GINT_TO_POINTER (-1));
+  }
+  if (!g_hash_table_lookup (hash, s1->v2)) {
+    (*func) (s1->v2, data);
+    g_hash_table_insert (hash, s1->v2, GINT_TO_POINTER (-1));
+  }
+  if (!g_hash_table_lookup (hash, gts_triangle_vertex (t))) {
+    (*func) (gts_triangle_vertex (t), data);
+    g_hash_table_insert (hash, gts_triangle_vertex (t), 
+			 GINT_TO_POINTER (-1));
+  }
+#ifdef USE_SURFACE_BTREE
+  return FALSE;
+#endif /* USE_SURFACE_BTREE */
+}
+
+/**
+ * gts_surface_foreach_vertex:
+ * @s: a #GtsSurface.
+ * @func: a #GtsFunc.
+ * @data: user data to be passed to @func.
+ *
+ * Calls @func once for each vertex of @s.
+ */
+void gts_surface_foreach_vertex (GtsSurface * s, GtsFunc func, gpointer data)
+{
+  gpointer info[3];
+
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (func != NULL);
+
+  /* forbid removal of faces */
+  s->keep_faces = TRUE;
+  info[0] = g_hash_table_new (NULL, NULL);
+  info[1] = data;
+  info[2] = func;
+#ifdef USE_SURFACE_BTREE
+  g_tree_traverse (s->faces, (GTraverseFunc) vertex_foreach_face, G_IN_ORDER,
+		   info);
+#else /* not USE_SURFACE_BTREE */
+  g_hash_table_foreach (s->faces, (GHFunc) vertex_foreach_face, info);
+#endif /* not USE_SURFACE_BTREE */
+  g_hash_table_destroy (info[0]);
+  /* allow removal of faces */
+  s->keep_faces = FALSE;
+}
+
+#ifdef USE_SURFACE_BTREE
+static gint edge_foreach_face (GtsTriangle * t,
+			       gpointer t_data, 
+			       gpointer * info)
+#else /* not USE_SURFACE_BTREE */
+static void edge_foreach_face (GtsTriangle * t,
+			       gpointer t_data, 
+			       gpointer * info)
+#endif /* not USE_SURFACE_BTREE */
+{
+  GHashTable * hash = info[0];
+  gpointer data = info[1];
+  GtsFunc func = (GtsFunc) info[2];
+
+  if (!g_hash_table_lookup (hash, t->e1)) {
+    (*func) (t->e1, data);
+    g_hash_table_insert (hash, t->e1, GINT_TO_POINTER (-1));
+  }
+  if (!g_hash_table_lookup (hash, t->e2)) {
+    (*func) (t->e2, data);
+    g_hash_table_insert (hash, t->e2, GINT_TO_POINTER (-1));
+  }
+  if (!g_hash_table_lookup (hash, t->e3)) {
+    (*func) (t->e3, data);
+    g_hash_table_insert (hash, t->e3, GINT_TO_POINTER (-1));
+  }
+#ifdef USE_SURFACE_BTREE
+  return FALSE;
+#endif /* not USE_SURFACE_BTREE */
+}
+
+/**
+ * gts_surface_foreach_edge:
+ * @s: a #GtsSurface.
+ * @func: a #GtsFunc.
+ * @data: user data to be passed to @func.
+ *
+ * Calls @func once for each edge of @s.
+ */
+void gts_surface_foreach_edge (GtsSurface * s, GtsFunc func, gpointer data)
+{
+  gpointer info[3];
+
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (func != NULL);
+  
+  /* forbid removal of faces */
+  s->keep_faces = TRUE;
+  info[0] = g_hash_table_new (NULL, NULL);
+  info[1] = data;
+  info[2] = func;
+#ifdef USE_SURFACE_BTREE
+  g_tree_traverse (s->faces, (GTraverseFunc) edge_foreach_face, G_IN_ORDER,
+		   info);
+#else /* not USE_SURFACE_BTREE */
+  g_hash_table_foreach (s->faces, (GHFunc) edge_foreach_face, info);
+#endif /* not USE_SURFACE_BTREE */
+  g_hash_table_destroy (info[0]);
+  /* allow removal of faces */
+  s->keep_faces = FALSE;
+}
+
+#ifdef USE_SURFACE_BTREE
+static gint foreach_face (GtsFace * f, 
+			  gpointer t_data,
+			  gpointer * info)
+#else /* not USE_SURFACE_BTREE */
+static void foreach_face (GtsFace * f, 
+			  gpointer t_data,
+			  gpointer * info)
+#endif /* not USE_SURFACE_BTREE */
+{
+  (*((GtsFunc) info[0])) (f, info[1]);
+#ifdef USE_SURFACE_BTREE
+  return FALSE;
+#endif /* USE_SURFACE_BTREE */
+}
+
+/**
+ * gts_surface_foreach_face:
+ * @s: a #GtsSurface.
+ * @func: a #GtsFunc.
+ * @data: user data to be passed to @func.
+ *
+ * Calls @func once for each face of @s.
+ */
+void gts_surface_foreach_face (GtsSurface * s,
+			       GtsFunc func, 
+			       gpointer data)
+{
+  gpointer info[2];
+
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (func != NULL);
+
+  /* forbid removal of faces */
+  s->keep_faces = TRUE;
+  info[0] = func;
+  info[1] = data;
+#ifdef USE_SURFACE_BTREE
+  g_tree_traverse (s->faces, (GTraverseFunc) foreach_face, G_IN_ORDER,
+		   info);
+#else /* not USE_SURFACE_BTREE */
+  g_hash_table_foreach (s->faces, (GHFunc) foreach_face, info);
+#endif /* not USE_SURFACE_BTREE */
+  /* allow removal of faces */
+  s->keep_faces = FALSE;
+}
+
+#ifdef USE_SURFACE_BTREE
+static gint foreach_face_remove (GtsFace * f,
+				 gpointer t_data,
+				 gpointer * info)
+{
+  if ((*((GtsFunc) info[0])) (f, info[1])) {
+    GtsSurface * s = info[2];
+    guint * n = info[3];
+
+    f->surfaces = g_slist_remove (f->surfaces, s);
+    if (!GTS_OBJECT_DESTROYED (f) &&
+	!gts_allow_floating_faces && 
+	f->surfaces == NULL)
+      gts_object_destroy (GTS_OBJECT (f));
+    
+    if (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->remove_face)
+      (* GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->remove_face) (s, f);
+
+    g_tree_remove (s->faces, f);
+    (*n)++;
+  }
+  return FALSE;
+}
+#else /* not USE_SURFACE_BTREE */
+static gboolean foreach_face_remove (GtsFace * f,
+				     gpointer t_data,
+				     gpointer * info)
+{
+  if ((*((GtsFunc) info[0])) (f, info[1])) {
+    GtsSurface * s = info[2];
+
+    f->surfaces = g_slist_remove (f->surfaces, s);
+    if (!GTS_OBJECT_DESTROYED (f) &&
+	!gts_allow_floating_faces && 
+	f->surfaces == NULL)
+      gts_object_destroy (GTS_OBJECT (f));
+    
+    if (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->remove_face)
+      (* GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->remove_face) (s, f);
+
+    return TRUE;
+  }
+  return FALSE;
+}
+#endif /* not USE_SURFACE_BTREE */
+
+/**
+ * gts_surface_foreach_face_remove:
+ * @s: a #GtsSurface.
+ * @func: a #GtsFunc.
+ * @data: user data to be passed to @func.
+ *
+ * Calls @func once for each face of @s. If @func returns %TRUE the
+ * corresponding face is removed from @s (and destroyed if it does not
+ * belong to any other surface and #gts_allow_floating_faces is set to
+ * %FALSE).
+ *
+ * Returns: the number of faces removed from @s.  
+ */
+guint gts_surface_foreach_face_remove (GtsSurface * s,
+				       GtsFunc func, 
+				       gpointer data)
+{
+  gpointer info[4];
+  guint n = 0;
+
+  g_return_val_if_fail (s != NULL, 0);
+  g_return_val_if_fail (func != NULL, 0);
+
+  /* forbid removal of faces */
+  s->keep_faces = TRUE;
+  info[0] = func;
+  info[1] = data;
+  info[2] = s;
+#ifdef USE_SURFACE_BTREE
+  info[3] = &n;
+  g_tree_traverse (s->faces, (GTraverseFunc) foreach_face_remove, G_PRE_ORDER,
+		   info);
+#else /* not USE_SURFACE_BTREE */
+  n = g_hash_table_foreach_remove (s->faces, 
+				   (GHRFunc) foreach_face_remove, 
+				   info);
+#endif /* not USE_SURFACE_BTREE */
+  /* allow removal of faces */
+  s->keep_faces = FALSE;
+  
+  return n;
+}
+
+static void midvertex_insertion (GtsEdge * e,
+				 GtsSurface * surface,
+				 GtsEHeap * heap,
+				 GtsRefineFunc refine_func,
+				 gpointer refine_data,
+				 GtsVertexClass * vertex_class,
+				 GtsEdgeClass * edge_class)
+{
+  GtsVertex * midvertex;
+  GtsEdge * e1, * e2;
+  GSList * i;
+
+  midvertex = (*refine_func) (e, vertex_class, refine_data);
+  e1 = gts_edge_new (edge_class, GTS_SEGMENT (e)->v1, midvertex);
+  gts_eheap_insert (heap, e1);
+  e2 = gts_edge_new (edge_class, GTS_SEGMENT (e)->v2, midvertex);
+  gts_eheap_insert (heap, e2);
+  
+  /* creates new faces and modifies old ones */
+  i = e->triangles;
+  while (i) {
+    GtsTriangle * t = i->data;
+    GtsVertex * v1, * v2, * v3;
+    GtsEdge * te2, * te3, * ne, * tmp;
+
+    gts_triangle_vertices_edges (t, e, &v1, &v2, &v3, &e, &te2, &te3);
+    ne = gts_edge_new (edge_class, midvertex, v3);
+    gts_eheap_insert (heap, ne);
+    if (GTS_SEGMENT (e1)->v1 == v2) {
+      tmp = e1; e1 = e2; e2 = tmp;
+    }
+    e1->triangles = g_slist_prepend (e1->triangles, t);
+    ne->triangles = g_slist_prepend (ne->triangles, t);
+    te2->triangles = g_slist_remove (te2->triangles, t);
+    t->e1 = e1; t->e2 = ne; t->e3 = te3;
+    gts_surface_add_face (surface, 
+			  gts_face_new (surface->face_class, e2, te2, ne));
+    i = i->next;
+  }
+  /* destroys edge */
+  g_slist_free (e->triangles);
+  e->triangles = NULL;
+  gts_object_destroy (GTS_OBJECT (e));
+}
+
+static gdouble edge_length2_inverse (GtsSegment * s)
+{
+  return - gts_point_distance2 (GTS_POINT (s->v1), GTS_POINT (s->v2));
+}
+
+static void create_heap_refine (GtsEdge * e, GtsEHeap * heap)
+{
+  gts_eheap_insert (heap, e);
+}
+
+/**
+ * gts_surface_refine:
+ * @surface: a #GtsSurface.
+ * @cost_func: a function returning the cost for a given edge.
+ * @cost_data: user data to be passed to @cost_func.
+ * @refine_func: a #GtsRefineFunc.
+ * @refine_data: user data to be passed to @refine_func.
+ * @stop_func: a #GtsStopFunc.
+ * @stop_data: user data to be passed to @stop_func.
+ *
+ * Refine @surface using a midvertex insertion technique. All the
+ * edges of @surface are ordered according to @cost_func. The edges
+ * are then processed in order until @stop_func returns %TRUE. Each
+ * edge is split in two and new edges and faces are created.
+ *
+ * If @cost_func is set to %NULL, the edges are sorted according 
+ * to their length squared (the longest is on top).
+ *
+ * If @refine_func is set to %NULL gts_segment_midvertex() is used.
+ * 
+ */
+void gts_surface_refine (GtsSurface * surface,
+			 GtsKeyFunc cost_func,
+			 gpointer cost_data,
+			 GtsRefineFunc refine_func,
+			 gpointer refine_data,
+			 GtsStopFunc stop_func,
+			 gpointer stop_data)
+{
+  GtsEHeap * heap;
+  GtsEdge * e;
+  gdouble top_cost;
+
+  g_return_if_fail (surface != NULL);
+  g_return_if_fail (stop_func != NULL);
+
+  if (cost_func == NULL)
+    cost_func = (GtsKeyFunc) edge_length2_inverse;
+  if (refine_func == NULL)
+    refine_func = (GtsRefineFunc) gts_segment_midvertex;
+
+  heap = gts_eheap_new (cost_func, cost_data);
+  gts_eheap_freeze (heap);
+  gts_surface_foreach_edge (surface, (GtsFunc) create_heap_refine, heap);
+  gts_eheap_thaw (heap);
+  while ((e = gts_eheap_remove_top (heap, &top_cost)) &&
+	 !(*stop_func) (top_cost,
+			gts_eheap_size (heap) + 
+			gts_edge_face_number (e, surface) + 2,
+			stop_data))
+    midvertex_insertion (e, surface, heap, refine_func, refine_data,
+			 surface->vertex_class, surface->edge_class);
+  gts_eheap_destroy (heap);
+}
+
+static GSList * edge_triangles (GtsEdge * e1, GtsEdge * e)
+{
+  GSList * i = e1->triangles;
+  GSList * triangles = NULL;
+  
+  while (i) {
+    GtsTriangle * t = i->data;
+    if (t->e1 == e || t->e2 == e || t->e3 == e) {
+      GtsEdge * e2;
+      GSList * j;
+      if (t->e1 == e) {
+	if (t->e2 == e1)
+	  e2 = t->e3;
+	else
+	  e2 = t->e2;
+      }
+      else if (t->e2 == e) {
+	if (t->e3 == e1)
+	  e2 = t->e1;
+	else
+	  e2 = t->e3;
+      }
+      else {
+	if (t->e2 == e1)
+	  e2 = t->e1;
+	else
+	  e2 = t->e2;
+      }
+      j = e2->triangles;
+      while (j) {
+	GtsTriangle * t = j->data;
+	if (t->e1 != e && t->e2 != e && t->e3 != e)
+	  triangles = g_slist_prepend (triangles, t);
+	j = j->next;
+      }
+    }
+    else
+      triangles = g_slist_prepend (triangles, t);
+    i = i->next;
+  }
+  return triangles;
+}
+
+static void replace_vertex (GSList * i, GtsVertex * v1, GtsVertex * v)
+{
+  while (i) {
+    GtsSegment * s = i->data;
+    if (s->v1 == v1)
+      s->v1 = v;
+    else
+      s->v2 = v;
+    i = i->next;
+  }
+}
+
+/**
+ * gts_edge_collapse_creates_fold:
+ * @e: a #GtsEdge.
+ * @v: a #GtsVertex.
+ * @max:  the maximum value of the square of the cosine of the angle between
+ * two triangles.
+ *
+ * Returns: %TRUE if collapsing edge @e to vertex @v would create
+ * faces making an angle the cosine squared of which would be larger than max,
+ * %FALSE otherwise.  
+ */
+gboolean gts_edge_collapse_creates_fold (GtsEdge * e, 
+					 GtsVertex * v,
+					 gdouble max)
+{
+  GtsVertex * v1, * v2;
+  GtsSegment * s;
+  GSList * i;
+  gboolean folded = FALSE;
+
+  g_return_val_if_fail (e != NULL, TRUE);
+  g_return_val_if_fail (v != NULL, TRUE);
+
+  s = GTS_SEGMENT (e);
+  v1 = s->v1;
+  v2 = s->v2;
+  replace_vertex (v1->segments, v1, v);
+  replace_vertex (v2->segments, v2, v);
+
+  i = v1->segments;
+  while (i && !folded) {
+    GtsSegment * s = i->data;
+    if (GTS_IS_EDGE (s)) {
+      GtsEdge * e1 = GTS_EDGE (s);
+      if (e1 != e) {
+	GSList * triangles = edge_triangles (e1, e);
+	folded = gts_triangles_are_folded (triangles, s->v1, s->v2, max);
+	g_slist_free (triangles);
+      }
+    }
+    i = i->next;
+  }
+
+  i = v2->segments;
+  while (i && !folded) {
+    GtsSegment * s = i->data;
+    if (GTS_IS_EDGE (s)) {
+      GtsEdge * e1 = GTS_EDGE (s);
+      if (e1 != e) {
+	GSList * triangles = edge_triangles (e1, e);
+	folded = gts_triangles_are_folded (triangles, s->v1, s->v2, max);
+	g_slist_free (triangles);
+      }
+    }
+    i = i->next;
+  }
+#if 1
+  if (!folded) {
+    GSList * triangles = gts_vertex_triangles (v1, NULL);
+    i = triangles = gts_vertex_triangles (v2, triangles);
+    while (i && !folded) {
+      GtsTriangle * t = i->data;
+      if (t->e1 != e && t->e2 != e && t->e3 != e) {
+	GtsEdge * e1 = gts_triangle_edge_opposite (t, v);
+	g_assert (e1);
+	folded = gts_triangles_are_folded (e1->triangles, 
+					   GTS_SEGMENT (e1)->v1,
+					   GTS_SEGMENT (e1)->v2,
+					   max);
+      }
+      i = i->next;
+    }
+    g_slist_free (triangles);
+  }
+#endif
+  replace_vertex (v1->segments, v, v1);
+  replace_vertex (v2->segments, v, v2);
+  return folded;
+}
+
+/**
+ * gts_edge_collapse_is_valid:
+ * @e: a #GtsEdge.
+ *
+ * An implementation of the topological constraints described in the 
+ * "Mesh Optimization" article of Hoppe et al (1993).
+ *
+ * Returns: %TRUE if @e can be collapsed without violation of the topological
+ * constraints, %FALSE otherwise.
+ */
+gboolean gts_edge_collapse_is_valid (GtsEdge * e)
+{
+  GSList * i;
+
+  g_return_val_if_fail (e != NULL, FALSE);
+
+  i = GTS_SEGMENT (e)->v1->segments;
+  while (i) {
+    GtsEdge * e1 = i->data;
+    if (e1 != e && GTS_IS_EDGE (e1)) {
+      GtsEdge * e2 = NULL;
+      GSList * j = GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e)->v1 ? 
+	GTS_SEGMENT (e1)->v2->segments : GTS_SEGMENT (e1)->v1->segments;
+      while (j && !e2) {
+	GtsEdge * e1 = j->data;
+	if (GTS_IS_EDGE (e1) && 
+	    (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e)->v2 || 
+	     GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e)->v2))
+	  e2 = e1;
+	j = j->next;
+      }
+      if (e2 && !gts_triangle_use_edges (e, e1, e2))
+	return FALSE;
+    }
+    i = i->next;
+  }
+
+  if (gts_edge_is_boundary (e, NULL)) {
+    GtsTriangle * t = e->triangles->data;
+    if (gts_edge_is_boundary (t->e1, NULL) &&
+	gts_edge_is_boundary (t->e2, NULL) &&
+	gts_edge_is_boundary (t->e3, NULL))
+      return FALSE;
+  }
+  else {
+    if (gts_vertex_is_boundary (GTS_SEGMENT (e)->v1, NULL) &&
+	gts_vertex_is_boundary (GTS_SEGMENT (e)->v2, NULL))
+      return FALSE;    
+    if (gts_edge_belongs_to_tetrahedron (e))
+      return FALSE;
+  }
+
+  return TRUE;
+}
+
+#define HEAP_INSERT_EDGE(h, e) (GTS_OBJECT (e)->reserved = gts_eheap_insert (h, e))
+#define HEAP_REMOVE_EDGE(h, e) (gts_eheap_remove (h, GTS_OBJECT (e)->reserved),\
+                                GTS_OBJECT (e)->reserved = NULL)
+
+static GtsVertex * edge_collapse (GtsEdge * e,
+				  GtsEHeap * heap,
+				  GtsCoarsenFunc coarsen_func,
+				  gpointer coarsen_data,
+				  GtsVertexClass * klass,
+				  gdouble maxcosine2)
+{
+  GSList * i;
+  GtsVertex  * v1 = GTS_SEGMENT (e)->v1, * v2 = GTS_SEGMENT (e)->v2, * mid;
+
+  /* if the edge is degenerate (i.e. v1 == v2), destroy and return */
+  if (v1 == v2) {
+    gts_object_destroy (GTS_OBJECT (e));
+    return NULL;
+  }
+
+  if (!gts_edge_collapse_is_valid (e)) {
+    GTS_OBJECT (e)->reserved = 
+      gts_eheap_insert_with_key (heap, e, G_MAXDOUBLE);
+    return NULL;
+  }
+
+  mid = (*coarsen_func) (e, klass, coarsen_data);
+
+  if (gts_edge_collapse_creates_fold (e, mid, maxcosine2)) {
+    GTS_OBJECT (e)->reserved = 
+      gts_eheap_insert_with_key (heap, e, G_MAXDOUBLE);
+    gts_object_destroy (GTS_OBJECT (mid));
+    return NULL;
+  }
+
+  gts_object_destroy (GTS_OBJECT (e));
+
+  gts_vertex_replace (v1, mid);
+  gts_object_destroy (GTS_OBJECT (v1));
+  gts_vertex_replace (v2, mid);
+  gts_object_destroy (GTS_OBJECT (v2));
+
+  /* destroy duplicate edges */
+  i = mid->segments;
+  while (i) {
+    GtsEdge * e1 = i->data;
+    GtsEdge * duplicate;
+    while ((duplicate = gts_edge_is_duplicate (e1))) {
+      gts_edge_replace (duplicate, GTS_EDGE (e1));
+      HEAP_REMOVE_EDGE (heap, duplicate);
+      gts_object_destroy (GTS_OBJECT (duplicate));
+    }
+    i = i->next;
+    if (!e1->triangles) {
+      /* e1 is the result of the collapse of one edge of a pair of identical
+	 faces (it should not happen unless duplicate triangles are present in
+	 the initial surface) */
+      g_warning ("file %s: line %d (%s): probably duplicate triangle.",
+		 __FILE__, __LINE__, G_GNUC_PRETTY_FUNCTION);
+      HEAP_REMOVE_EDGE (heap, e1);
+      gts_object_destroy (GTS_OBJECT (e1));
+      if (i == NULL) /* mid has been destroyed */
+	mid = NULL;
+    }
+  }
+
+  return mid;
+}
+
+/*
+ * I don't see where this code is ever used, but keep it for a bit 
+ * in case it is needed for debugging
+ */
+#ifdef GTS_NEED_UPDATE_CLOSEST_NEIGHBORS
+static void update_closest_neighbors (GtsVertex * v, GtsEHeap * heap)
+{
+  GSList * i = v->segments;
+  
+  while (i) {
+    GtsSegment * s = i->data;
+    if (GTS_IS_EDGE (s)) {
+      HEAP_REMOVE_EDGE (heap, GTS_EDGE (s));
+      HEAP_INSERT_EDGE (heap, GTS_EDGE (s));
+    }
+    i = i->next;
+  }
+}
+#endif
+
+static void update_2nd_closest_neighbors (GtsVertex * v, GtsEHeap * heap)
+{
+  GSList * i = v->segments;
+  GSList * list = NULL;
+  
+  while (i) {
+    GtsSegment * s = i->data;
+    if (GTS_IS_EDGE (s)) {
+      GtsVertex * v1 = s->v1 == v ? s->v2 : s->v1;
+      GSList * j = v1->segments;
+      while (j) {
+	GtsSegment * s1 = j->data;
+	if (GTS_IS_EDGE (s1) && !g_slist_find (list, s1))
+	  list = g_slist_prepend (list, s1);
+	j = j->next;
+      }
+    }
+    i = i->next;
+  }
+
+  i = list;
+  while (i) {
+    GtsEdge * e = i->data;
+    HEAP_REMOVE_EDGE (heap, e);
+    HEAP_INSERT_EDGE (heap, e);
+    i = i->next;
+  }
+
+  g_slist_free (list);
+}
+
+static gdouble edge_length2 (GtsEdge * e)
+{
+  return gts_point_distance2 (GTS_POINT (GTS_SEGMENT (e)->v1), 
+			      GTS_POINT (GTS_SEGMENT (e)->v2));
+}
+
+static void create_heap_coarsen (GtsEdge * e, GtsEHeap * heap)
+{
+  HEAP_INSERT_EDGE (heap, e);
+}
+
+/**
+ * gts_surface_coarsen:
+ * @surface: a #GtsSurface.
+ * @cost_func: a function returning the cost for a given edge.
+ * @cost_data: user data to be passed to @cost_func.
+ * @coarsen_func: a #GtsCoarsenVertexFunc.
+ * @coarsen_data: user data to be passed to @coarsen_func.
+ * @stop_func: a #GtsStopFunc.
+ * @stop_data: user data to be passed to @stop_func.
+ * @minangle: minimum angle between two neighboring triangles.
+ *
+ * The edges of @surface are sorted according to @cost_func to 
+ * create a priority heap (a #GtsEHeap). The edges are extracted in
+ * turn from the top of the heap and collapsed (i.e. the vertices are
+ * replaced by the vertex returned by the @coarsen_func function)
+ * until the @stop_func functions returns %TRUE.
+ *
+ * If @cost_func is set to %NULL, the edges are sorted according 
+ * to their length squared (the shortest is on top).
+ *
+ * If @coarsen_func is set to %NULL gts_segment_midvertex() is used.
+ *
+ * The minimum angle is used to avoid introducing faces which would be folded.
+ */
+void gts_surface_coarsen (GtsSurface * surface,
+			  GtsKeyFunc cost_func,
+			  gpointer cost_data,
+			  GtsCoarsenFunc coarsen_func,
+			  gpointer coarsen_data,
+			  GtsStopFunc stop_func,
+			  gpointer stop_data,
+			  gdouble minangle)
+{
+  GtsEHeap * heap;
+  GtsEdge * e;
+  gdouble top_cost;
+  gdouble maxcosine2;
+
+  g_return_if_fail (surface != NULL);
+  g_return_if_fail (stop_func != NULL);
+
+  if (cost_func == NULL)
+    cost_func = (GtsKeyFunc) edge_length2;
+  if (coarsen_func == NULL)
+    coarsen_func = (GtsCoarsenFunc) gts_segment_midvertex;
+
+  heap = gts_eheap_new (cost_func, cost_data);
+  maxcosine2 = cos (minangle); maxcosine2 *= maxcosine2;
+
+  gts_eheap_freeze (heap);
+  gts_surface_foreach_edge (surface, (GtsFunc) create_heap_coarsen, heap);
+  gts_eheap_thaw (heap);
+  /* we want to control edge destruction manually */
+  gts_allow_floating_edges = TRUE;
+  while ((e = gts_eheap_remove_top (heap, &top_cost)) &&
+	 (top_cost < G_MAXDOUBLE) &&
+	 !(*stop_func) (top_cost, gts_eheap_size (heap) - 
+			gts_edge_face_number (e, surface), stop_data))
+    {
+      GtsVertex * v = edge_collapse (e, heap, coarsen_func, coarsen_data,
+				     surface->vertex_class, maxcosine2);
+      if (v != NULL)
+	update_2nd_closest_neighbors (v, heap);
+    }
+  gts_allow_floating_edges = FALSE;
+
+  /* set reserved field of remaining edges back to NULL */
+  if (e) GTS_OBJECT (e)->reserved = NULL;
+  gts_eheap_foreach (heap, (GFunc) gts_object_reset_reserved, NULL);
+
+  gts_eheap_destroy (heap);
+}
+
+/**
+ * gts_coarsen_stop_number:
+ * @cost: the cost of the edge collapse considered.
+ * @nedge: the current number of edges of the surface being simplified.
+ * @min_number: a pointer to the minimum number of edges desired for the 
+ * surface being simplified.
+ *
+ * This function is to be used as the @stop_func argument of 
+ * gts_surface_coarsen() or gts_psurface_new().
+ *
+ * Returns: %TRUE if the edge collapse would create a surface with a smaller 
+ * number of edges than given by @min_number, %FALSE otherwise.
+ */
+gboolean gts_coarsen_stop_number (gdouble cost, 
+				  guint nedge, 
+				  guint * min_number)
+{
+  g_return_val_if_fail (min_number != NULL, TRUE);
+
+  if (nedge < *min_number)
+    return TRUE;
+  return FALSE;
+}
+
+/**
+ * gts_coarsen_stop_cost:
+ * @cost: the cost of the edge collapse considered.
+ * @nedge: the current number of edges of the surface being simplified.
+ * @max_cost: a pointer to the maximum cost allowed for an edge collapse.
+ *
+ * This function is to be used as the @stop_func argument of 
+ * gts_surface_coarsen() or gts_psurface_new().
+ *
+ * Returns: %TRUE if the cost of the edge collapse considered is larger than
+ * given by @max_cost, %FALSE otherwise.
+ */
+gboolean gts_coarsen_stop_cost (gdouble cost, 
+				guint nedge, 
+				gdouble * max_cost)
+{
+  g_return_val_if_fail (max_cost != NULL, TRUE);
+
+  if (cost > *max_cost)
+    return TRUE;
+  return FALSE;
+}
+
+#define GTS_M_ICOSAHEDRON_X /* sqrt(sqrt(5)+1)/sqrt(2*sqrt(5)) */ \
+  0.850650808352039932181540497063011072240401406
+#define GTS_M_ICOSAHEDRON_Y /* sqrt(2)/sqrt(5+sqrt(5))         */ \
+  0.525731112119133606025669084847876607285497935
+#define GTS_M_ICOSAHEDRON_Z 0.0
+
+static guint generate_icosahedron (GtsSurface * s)
+{
+  GtsVertex * v01 = gts_vertex_new (s->vertex_class,
+      +GTS_M_ICOSAHEDRON_Z, +GTS_M_ICOSAHEDRON_X, -GTS_M_ICOSAHEDRON_Y);
+  GtsVertex * v02 = gts_vertex_new (s->vertex_class,
+      +GTS_M_ICOSAHEDRON_X, +GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z);
+  GtsVertex * v03 = gts_vertex_new (s->vertex_class,
+      +GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z, -GTS_M_ICOSAHEDRON_X);
+  GtsVertex * v04 = gts_vertex_new (s->vertex_class,
+      +GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z, +GTS_M_ICOSAHEDRON_X);
+  GtsVertex * v05 = gts_vertex_new (s->vertex_class,
+      +GTS_M_ICOSAHEDRON_X, -GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z);
+  GtsVertex * v06 = gts_vertex_new (s->vertex_class,
+      +GTS_M_ICOSAHEDRON_Z, +GTS_M_ICOSAHEDRON_X, +GTS_M_ICOSAHEDRON_Y);
+  GtsVertex * v07 = gts_vertex_new (s->vertex_class,
+      -GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z, +GTS_M_ICOSAHEDRON_X);
+  GtsVertex * v08 = gts_vertex_new (s->vertex_class,
+      +GTS_M_ICOSAHEDRON_Z, -GTS_M_ICOSAHEDRON_X, -GTS_M_ICOSAHEDRON_Y);
+  GtsVertex * v09 = gts_vertex_new (s->vertex_class,
+      -GTS_M_ICOSAHEDRON_X, +GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z);
+  GtsVertex * v10 = gts_vertex_new (s->vertex_class,
+      -GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z, -GTS_M_ICOSAHEDRON_X);
+  GtsVertex * v11 = gts_vertex_new (s->vertex_class,
+      -GTS_M_ICOSAHEDRON_X, -GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z);
+  GtsVertex * v12 = gts_vertex_new (s->vertex_class,
+      +GTS_M_ICOSAHEDRON_Z, -GTS_M_ICOSAHEDRON_X, +GTS_M_ICOSAHEDRON_Y);
+
+  GtsEdge * e01 = gts_edge_new (s->edge_class, v01, v02);
+  GtsEdge * e02 = gts_edge_new (s->edge_class, v03, v02);
+  GtsEdge * e03 = gts_edge_new (s->edge_class, v01, v03);
+  GtsEdge * e04 = gts_edge_new (s->edge_class, v04, v05);
+  GtsEdge * e05 = gts_edge_new (s->edge_class, v02, v05);
+  GtsEdge * e06 = gts_edge_new (s->edge_class, v04, v02);
+  GtsEdge * e07 = gts_edge_new (s->edge_class, v06, v07);
+  GtsEdge * e08 = gts_edge_new (s->edge_class, v04, v07);
+  GtsEdge * e09 = gts_edge_new (s->edge_class, v06, v04);
+  GtsEdge * e10 = gts_edge_new (s->edge_class, v08, v03);
+  GtsEdge * e11 = gts_edge_new (s->edge_class, v03, v05);
+  GtsEdge * e12 = gts_edge_new (s->edge_class, v08, v05);
+  GtsEdge * e13 = gts_edge_new (s->edge_class, v06, v09);
+  GtsEdge * e14 = gts_edge_new (s->edge_class, v07, v09);
+  GtsEdge * e15 = gts_edge_new (s->edge_class, v08, v10);
+  GtsEdge * e16 = gts_edge_new (s->edge_class, v03, v10);
+  GtsEdge * e17 = gts_edge_new (s->edge_class, v06, v01);
+  GtsEdge * e18 = gts_edge_new (s->edge_class, v01, v09);
+  GtsEdge * e19 = gts_edge_new (s->edge_class, v08, v11);
+  GtsEdge * e20 = gts_edge_new (s->edge_class, v10, v11);
+  GtsEdge * e21 = gts_edge_new (s->edge_class, v06, v02);
+  GtsEdge * e22 = gts_edge_new (s->edge_class, v12, v11);
+  GtsEdge * e23 = gts_edge_new (s->edge_class, v12, v08);
+  GtsEdge * e24 = gts_edge_new (s->edge_class, v12, v07);
+  GtsEdge * e25 = gts_edge_new (s->edge_class, v07, v11);
+  GtsEdge * e26 = gts_edge_new (s->edge_class, v12, v04);
+  GtsEdge * e27 = gts_edge_new (s->edge_class, v09, v11);
+  GtsEdge * e28 = gts_edge_new (s->edge_class, v10, v09);
+  GtsEdge * e29 = gts_edge_new (s->edge_class, v12, v05);
+  GtsEdge * e30 = gts_edge_new (s->edge_class, v01, v10);
+  
+  gts_surface_add_face (s, gts_face_new (s->face_class, e01, e02, e03));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e04, e05, e06));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e07, e08, e09));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e10, e11, e12));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e13, e14, e07));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e15, e16, e10));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e17, e18, e13));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e19, e20, e15));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e21, e01, e17));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e22, e19, e23));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e09, e06, e21));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e24, e25, e22));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e26, e08, e24));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e20, e27, e28));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e29, e04, e26));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e14, e27, e25));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e23, e12, e29));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e02, e05, e11));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e30, e28, e18));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e03, e16, e30));
+
+  return 0;
+}
+
+static GtsVertex * unit_sphere_arc_midvertex (GtsSegment * s, 
+					      GtsVertexClass * vertex_class)
+{
+  GtsPoint * p1, * p2;
+  gdouble x, y, z, norm;
+
+  p1 = GTS_POINT (s->v1); p2 = GTS_POINT (s->v2);
+
+  x = 0.5*(p1->x + p2->x);
+  y = 0.5*(p1->y + p2->y);
+  z = 0.5*(p1->z + p2->z);
+
+  norm = x*x + y*y + z*z;
+  norm = sqrt (norm);
+
+  x /= norm; y /= norm; z /= norm;
+
+  return gts_vertex_new (vertex_class, x, y, z);
+}
+
+static void tessellate_face (GtsFace * f,
+			     GtsSurface * s,
+			     GtsRefineFunc refine_func,
+			     gpointer refine_data,
+			     GtsVertexClass * vertex_class,
+			     GtsEdgeClass * edge_class)
+{
+  GtsTriangle * t;
+  GtsEdge * e1, * e2, * e3;                          /* former edges     */
+  GtsVertex * v1, * v2, * v3;                        /* initial vertices */
+  GtsVertex * v4, * v5, * v6;                        /* new vertices     */ 
+  GtsEdge * e56, * e64, * e45;                       /* new inside edges */
+  GtsEdge * e24, * e34, * e35, * e15, * e16, * e26;  /* new border edges */
+  GSList * dum;
+  GtsEdge * edum;
+  
+  t = GTS_TRIANGLE (f);
+  e1 = t->e1; e2 = t->e2; e3 = t->e3;
+
+  if (GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v1) {
+    v1 = GTS_SEGMENT (e2)->v2;
+    v2 = GTS_SEGMENT (e1)->v1;
+    v3 = GTS_SEGMENT (e1)->v2;
+  }
+  else if (GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v2) {
+    v1 = GTS_SEGMENT (e2)->v1;
+    v2 = GTS_SEGMENT (e1)->v1;
+    v3 = GTS_SEGMENT (e1)->v2;
+  }
+  else if (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e2)->v1) {
+    v1 = GTS_SEGMENT (e2)->v2;
+    v2 = GTS_SEGMENT (e1)->v2;
+    v3 = GTS_SEGMENT (e1)->v1;
+  }
+  else if (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e2)->v2) {
+    v1 = GTS_SEGMENT (e2)->v1;
+    v2 = GTS_SEGMENT (e1)->v2;
+    v3 = GTS_SEGMENT (e1)->v1;
+  }
+  else {
+    v1 = v2 = v3 = NULL;
+    g_assert_not_reached ();
+  }
+
+  e1->triangles = g_slist_remove (e1->triangles, t);
+  e2->triangles = g_slist_remove (e2->triangles, t);
+  e3->triangles = g_slist_remove (e3->triangles, t);
+  
+  if (GTS_OBJECT (e1)->reserved) {
+    dum = (GTS_OBJECT (e1)->reserved);
+    e24 = dum->data;
+    e34 = dum->next->data;
+    v4 = GTS_SEGMENT (e24)->v2;
+    if (GTS_SEGMENT (e24)->v1 == v3) {
+      edum = e34; e34 = e24; e24 = edum;
+    }
+  }
+  else {
+    v4 = (*refine_func) (e1, vertex_class, refine_data);
+    e24 = gts_edge_new (edge_class, v2, v4);
+    e34 = gts_edge_new (edge_class, v3, v4);
+    dum = g_slist_append (NULL, e24);
+    dum = g_slist_append (dum,  e34);
+    GTS_OBJECT (e1)->reserved = dum;
+  }
+  if (GTS_OBJECT (e2)->reserved) {
+    dum = (GTS_OBJECT (e2)->reserved);
+    e35 = dum->data;
+    e15 = dum->next->data;
+    v5 = GTS_SEGMENT (e35)->v2;
+    if (GTS_SEGMENT (e35)->v1 == v1) {
+      edum = e15; e15 = e35; e35 = edum;
+    }
+  }
+  else {
+    v5 = (*refine_func) (e2, vertex_class, refine_data);
+    e35 = gts_edge_new (edge_class, v3, v5);
+    e15 = gts_edge_new (edge_class, v1, v5);
+    dum = g_slist_append (NULL, e35);
+    dum = g_slist_append (dum,  e15);
+    GTS_OBJECT (e2)->reserved = dum;
+  }
+  if (GTS_OBJECT (e3)->reserved) {
+    dum = (GTS_OBJECT (e3)->reserved);
+    e16 = dum->data;
+    e26 = dum->next->data;
+    v6 = GTS_SEGMENT (e16)->v2;
+    if (GTS_SEGMENT (e16)->v1 == v2) {
+      edum = e16; e16 = e26; e26 = edum;
+    }
+  }
+  else {
+    v6 = (*refine_func) (e3, vertex_class, refine_data);
+    e16 = gts_edge_new (edge_class, v1, v6);
+    e26 = gts_edge_new (edge_class, v2, v6);
+    dum = g_slist_append (NULL, e16);
+    dum = g_slist_append (dum,  e26);
+    GTS_OBJECT (e3)->reserved = dum;
+  }
+  
+  if (e1->triangles == NULL) {
+    g_slist_free (GTS_OBJECT (e1)->reserved);
+    GTS_OBJECT (e1)->reserved = NULL;
+    gts_object_destroy (GTS_OBJECT (e1));
+    e1 = NULL;
+  }
+  if (e2->triangles == NULL) {
+    g_slist_free (GTS_OBJECT (e2)->reserved);
+    GTS_OBJECT (e2)->reserved = NULL;
+    gts_object_destroy (GTS_OBJECT (e2));
+    e2 = NULL;
+  }
+  if (e3->triangles == NULL) {
+    g_slist_free (GTS_OBJECT (e3)->reserved);
+    GTS_OBJECT (e3)->reserved = NULL;
+    gts_object_destroy (GTS_OBJECT (e3));
+    e3 = NULL;
+  }
+
+  e56 = gts_edge_new (edge_class, v5, v6);
+  e64 = gts_edge_new (edge_class, v6, v4);
+  e45 = gts_edge_new (edge_class, v4, v5);
+  t->e1 = e56; e56->triangles = g_slist_prepend (e56->triangles, t);
+  t->e2 = e64; e64->triangles = g_slist_prepend (e64->triangles, t);
+  t->e3 = e45; e45->triangles = g_slist_prepend (e45->triangles, t);
+  
+  gts_surface_add_face (s, gts_face_new (s->face_class, e16, e56, e15));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e26, e24, e64));
+  gts_surface_add_face (s, gts_face_new (s->face_class, e45, e34, e35)); 
+}
+
+static void create_array_tessellate (GtsFace * f, GPtrArray * array)
+{
+  g_ptr_array_add (array, f);
+}
+
+/**
+ * gts_surface_tessellate:
+ * @s: a #GtsSurface.
+ * @refine_func: a #GtsRefineFunc.
+ * @refine_data: user data to be passed to @refine_func.
+ *
+ * Tessellate each triangle of @s with 4 triangles:   
+ * the number of triangles is increased by a factor of 4.
+ * http://mathworld.wolfram.com/GeodesicDome.html
+ *
+ * If @refine_func is set to %NULL a mid arc function is used: if
+ * the surface is a polyhedron with the unit sphere as circum sphere,
+ * then gts_surface_tessellate() corresponds to a geodesation step
+ * (see gts_surface_generate_sphere()).
+ * 
+ */
+void gts_surface_tessellate (GtsSurface * s,
+			     GtsRefineFunc refine_func,
+			     gpointer refine_data)
+{
+  GPtrArray * array;
+  guint i;
+
+  g_return_if_fail (s != NULL);
+  
+  if (refine_func == NULL) /* tessellate_surface == geodesate_surface */
+    refine_func = (GtsRefineFunc) unit_sphere_arc_midvertex;
+
+  array = g_ptr_array_new ();
+  gts_surface_foreach_face (s, (GtsFunc) create_array_tessellate, array);
+  for(i = 0; i < array->len; i++)
+    tessellate_face (g_ptr_array_index (array, i),
+		     s, refine_func, refine_data, 
+		     s->vertex_class, s->edge_class);
+  g_ptr_array_free (array, TRUE);
+}
+
+/**
+ * gts_surface_generate_sphere:
+ * @s: a #GtsSurface.
+ * @geodesation_order: a #guint.
+ *
+ * Add a triangulated unit sphere generated by recursive subdivision to @s.
+ * First approximation is an isocahedron; each level of refinement
+ * (@geodesation_order) increases the number of triangles by a factor of 4.
+ * http://mathworld.wolfram.com/GeodesicDome.html
+ *
+ * Returns: @s.
+ */
+GtsSurface * gts_surface_generate_sphere (GtsSurface * s, 
+					  guint geodesation_order)
+{
+  guint cgo; 
+
+  g_return_val_if_fail (s != NULL, NULL);
+  g_return_val_if_fail (geodesation_order != 0, NULL);
+
+  generate_icosahedron (s);
+
+  for (cgo = 1; cgo < geodesation_order; cgo++)
+    gts_surface_tessellate (s, NULL, NULL);
+  
+  return s;
+}
+
+static void foreach_vertex_copy (GtsPoint * p, GtsVertexClass * klass)
+{
+  GTS_OBJECT (p)->reserved = gts_vertex_new (klass, p->x, p->y, p->z);
+}
+
+static void foreach_edge_copy (GtsSegment * s, GtsEdgeClass * klass)
+{
+  GTS_OBJECT (s)->reserved = gts_edge_new (klass,
+					   GTS_OBJECT (s->v1)->reserved, 
+					   GTS_OBJECT (s->v2)->reserved);
+}
+
+static void foreach_face_copy (GtsTriangle * t,
+			       GtsSurface * s)
+{
+  gts_surface_add_face (s, gts_face_new (s->face_class,
+					 GTS_OBJECT (t->e1)->reserved,
+					 GTS_OBJECT (t->e2)->reserved,
+					 GTS_OBJECT (t->e3)->reserved));
+}
+
+/**
+ * gts_surface_copy:
+ * @s1: a #GtsSurface.
+ * @s2: a #GtsSurface.
+ *
+ * Add a copy of all the faces, edges and vertices of @s2 to @s1.
+ *
+ * Returns: @s1.
+ */
+GtsSurface * gts_surface_copy (GtsSurface * s1, GtsSurface * s2)
+{
+  g_return_val_if_fail (s1 != NULL, NULL);
+  g_return_val_if_fail (s2 != NULL, NULL);
+  
+  gts_surface_foreach_vertex (s2, (GtsFunc) foreach_vertex_copy, 
+			      s1->vertex_class);
+  gts_surface_foreach_edge (s2, (GtsFunc) foreach_edge_copy, s1->edge_class);
+  gts_surface_foreach_face (s2, (GtsFunc) foreach_face_copy, s1);
+
+  gts_surface_foreach_vertex (s2, (GtsFunc) gts_object_reset_reserved, NULL);
+  gts_surface_foreach_edge (s2, (GtsFunc) gts_object_reset_reserved, NULL);
+  
+  return s1;
+}
+
+static void merge_foreach_face (GtsFace * f, 
+				GtsSurface * s)
+{
+  gts_surface_add_face (s, f);
+}
+
+/**
+ * gts_surface_merge:
+ * @s: a #GtsSurface.
+ * @with: another #GtsSurface.
+ *
+ * Adds all the faces of @with which do not already belong to @s
+ * to @s.
+ */
+void gts_surface_merge (GtsSurface * s, GtsSurface * with)
+{
+  g_return_if_fail (s != NULL);
+  g_return_if_fail (with != NULL);
+  
+  gts_surface_foreach_face (with, (GtsFunc) merge_foreach_face, s);
+}
+
+static void manifold_foreach_edge (GtsEdge * e, gpointer * data)
+{
+  gboolean * is_manifold = data[0];
+
+  if (*is_manifold) {
+    if (gts_edge_face_number (e, data[1]) > 2)
+      *is_manifold = FALSE;
+  }
+}
+
+/**
+ * gts_surface_is_manifold:
+ * @s: a #GtsSurface.
+ *
+ * Returns: %TRUE if the surface is a manifold, %FALSE otherwise.
+ */
+gboolean gts_surface_is_manifold (GtsSurface * s)
+{
+  gboolean is_manifold = TRUE;
+  gpointer data[2];
+
+  g_return_val_if_fail (s != NULL, FALSE);
+
+  data[0] = &is_manifold;
+  data[1] = s;
+  gts_surface_foreach_edge (s, (GtsFunc) manifold_foreach_edge, data);
+  return is_manifold;
+}
+
+static void closed_foreach_edge (GtsEdge * e, gpointer * data)
+{
+  gboolean * is_closed = data[0];
+
+  if (*is_closed) {
+    if (gts_edge_face_number (e, data[1]) != 2)
+      *is_closed = FALSE;
+  }
+}
+
+/**
+ * gts_surface_is_closed:
+ * @s: a #GtsSurface.
+ *
+ * Returns: %TRUE if @s is a closed surface, %FALSE otherwise. Note that a
+ * closed surface is also a manifold.
+ */
+gboolean gts_surface_is_closed (GtsSurface * s)
+{
+  gboolean is_closed = TRUE;
+  gpointer data[2];
+
+  g_return_val_if_fail (s != NULL, FALSE);
+
+  data[0] = &is_closed;
+  data[1] = s;
+  gts_surface_foreach_edge (s, (GtsFunc) closed_foreach_edge, data);
+  return is_closed;
+}
+
+static void orientable_foreach_edge (GtsEdge * e, gpointer * data)
+{
+  gboolean * is_orientable = data[0];
+
+  if (*is_orientable) {
+    GtsSurface * surface = data[1];
+    GtsFace * f1 = NULL, * f2 = NULL;
+    GSList * i = e->triangles;
+    while (i && *is_orientable) {
+      GtsFace * f = i->data;
+      if (GTS_IS_FACE (f) && gts_face_has_parent_surface (f, surface)) {
+	if (!f1) f1 = f;
+	else if (!f2) f2 = f;
+	else *is_orientable = FALSE;
+      }
+      i = i->next;
+    }
+    if (f1 && f2 && !gts_triangles_are_compatible (GTS_TRIANGLE (f1), 
+						   GTS_TRIANGLE (f2), e))
+      *is_orientable = FALSE;
+  }
+}
+
+/**
+ * gts_surface_is_orientable:
+ * @s: a #GtsSurface.
+ *
+ * Returns: %TRUE if all the faces of @s have compatible orientation
+ * as checked by gts_faces_are_compatible(), %FALSE otherwise. Note that
+ * an orientable surface is also a manifold.
+ */
+gboolean gts_surface_is_orientable (GtsSurface * s)
+{
+  gboolean is_orientable = TRUE;
+  gpointer data[2];
+
+  g_return_val_if_fail (s != NULL, FALSE);
+
+  data[0] = &is_orientable;
+  data[1] = s;
+  gts_surface_foreach_edge (s, (GtsFunc) orientable_foreach_edge, data);
+  return is_orientable;
+}
+
+static void volume_foreach_face (GtsTriangle * t,
+				 gdouble * volume)
+{
+  GtsVertex * va, * vb, * vc;
+  GtsPoint * pa, * pb, * pc;
+
+  gts_triangle_vertices (t, &va, &vb, &vc);
+  pa = GTS_POINT (va);
+  pb = GTS_POINT (vb);
+  pc = GTS_POINT (vc);
+  
+  *volume += (pa->x * (pb->y * pc->z - pb->z * pc->y) +
+	      pb->x * (pc->y * pa->z - pc->z * pa->y) +
+	      pc->x * (pa->y * pb->z - pa->z * pb->y));
+}
+
+/**
+ * gts_surface_volume:
+ * @s: a #GtsSurface.
+ *
+ * Returns: the signed volume of the domain bounded by the surface @s. It
+ * makes sense only if @s is a closed and orientable manifold.
+ */
+gdouble gts_surface_volume (GtsSurface * s)
+{
+  gdouble volume = 0.0;
+
+  g_return_val_if_fail (s != NULL, 0.0);
+
+  gts_surface_foreach_face (s, (GtsFunc) volume_foreach_face, &volume);
+
+  return volume/6.;
+}
+
+static void center_of_mass_foreach_face (GtsTriangle * t,
+					 gpointer * data)
+{
+  GtsVertex * v1, * v2, * v3;
+  GtsPoint * p1, * p2, * p3;
+  gdouble x1, y1, z1, x2, y2, z2, nx, ny, nz;
+  gdouble * volume = data[0];
+  gdouble * cm = data[1];
+
+  gts_triangle_vertices (t, &v1, &v2, &v3);
+  p1 = GTS_POINT (v1);
+  p2 = GTS_POINT (v2);
+  p3 = GTS_POINT (v3);
+
+  x1 = p2->x - p1->x;
+  y1 = p2->y - p1->y;
+  z1 = p2->z - p1->z;
+
+  x2 = p3->x - p1->x;
+  y2 = p3->y - p1->y;
+  z2 = p3->z - p1->z;
+  
+  nx = y1*z2 - z1*y2;
+  ny = z1*x2 - x1*z2;
+  nz = x1*y2 - y1*x2;
+
+  cm[0] += nx*(p1->x*p1->x + p2->x*p2->x + p3->x*p3->x + 
+	       p1->x*p2->x + p1->x*p3->x + p2->x*p3->x);
+  cm[1] += ny*(p1->y*p1->y + p2->y*p2->y + p3->y*p3->y + 
+	       p1->y*p2->y + p1->y*p3->y + p2->y*p3->y);
+  cm[2] += nz*(p1->z*p1->z + p2->z*p2->z + p3->z*p3->z + 
+	       p1->z*p2->z + p1->z*p3->z + p2->z*p3->z);
+
+  *volume += nx*(p1->x + p2->x + p3->x);
+}
+
+
+/**
+ * gts_surface_center_of_mass:
+ * @s: a #GtsSurface.
+ * @cm: a #GtsVector.
+ *
+ * Fills @cm with the coordinates of the center of mass of @s.
+ *
+ * Returns: the signed volume of the domain bounded by the surface @s.
+ */
+gdouble gts_surface_center_of_mass (GtsSurface * s,
+				    GtsVector cm)
+{
+  gdouble volume = 0.;
+  gpointer data[2];
+
+  g_return_val_if_fail (s != NULL, 0.0);
+
+  data[0] = &volume;
+  data[1] = &(cm[0]);
+  cm[0] = cm[1] = cm[2] = 0.;
+  gts_surface_foreach_face (s, (GtsFunc) center_of_mass_foreach_face, data);
+  
+  if (volume != 0.) {
+    cm[0] /= 4.*volume;
+    cm[1] /= 4.*volume;
+    cm[2] /= 4.*volume;
+  }
+
+  return volume/6.;
+}
+
+static void center_of_area_foreach_face (GtsTriangle * t,
+					 gpointer * data)
+{
+  GtsVertex * v1, * v2, * v3;
+  GtsPoint * p1, * p2, * p3;
+  gdouble a;
+  gdouble * area = data[0];
+  gdouble * cm = data[1];
+
+  gts_triangle_vertices (t, &v1, &v2, &v3);
+  p1 = GTS_POINT (v1);
+  p2 = GTS_POINT (v2);
+  p3 = GTS_POINT (v3);
+
+  a = gts_triangle_area (t);
+  cm[0] += a*(p1->x + p2->x + p3->x);
+  cm[1] += a*(p1->y + p2->y + p3->y);
+  cm[2] += a*(p1->z + p2->z + p3->z);
+  *area += a;
+}
+
+
+/**
+ * gts_surface_center_of_area:
+ * @s: a #GtsSurface.
+ * @cm: a #GtsVector.
+ *
+ * Fills @cm with the coordinates of the center of area of @s.
+ *
+ * Returns: the area of surface @s.
+ */
+gdouble gts_surface_center_of_area (GtsSurface * s,
+				    GtsVector cm)
+{
+  gdouble area = 0.;
+  gpointer data[2];
+
+  g_return_val_if_fail (s != NULL, 0.0);
+
+  data[0] = &area;
+  data[1] = &(cm[0]);
+  cm[0] = cm[1] = cm[2] = 0.;
+  gts_surface_foreach_face (s, (GtsFunc) center_of_area_foreach_face, data);
+  
+  if (area != 0.) {
+    cm[0] /= 3.*area;
+    cm[1] /= 3.*area;
+    cm[2] /= 3.*area;
+  }
+
+  return area;
+}
+
+static void number_foreach (gpointer data, guint * n)
+{
+  (*n)++;
+}
+
+/**
+ * gts_surface_vertex_number:
+ * @s: a #GtsSurface.
+ *
+ * Returns: the number of vertices of @s.
+ */
+guint gts_surface_vertex_number (GtsSurface * s)
+{
+  guint n = 0;
+
+  g_return_val_if_fail (s != NULL, 0);
+
+  gts_surface_foreach_vertex (s, (GtsFunc) number_foreach, &n);
+
+  return n;
+}
+
+/**
+ * gts_surface_edge_number:
+ * @s: a #GtsSurface.
+ *
+ * Returns: the number of edges of @s.
+ */
+guint gts_surface_edge_number (GtsSurface * s)
+{
+  guint n = 0;
+
+  g_return_val_if_fail (s != NULL, 0);
+
+  gts_surface_foreach_edge (s, (GtsFunc) number_foreach, &n);
+
+  return n;
+}
+
+/**
+ * gts_surface_face_number:
+ * @s: a #GtsSurface.
+ *
+ * Returns: the number of faces of @s
+ */
+guint gts_surface_face_number (GtsSurface * s)
+{
+  g_return_val_if_fail (s != NULL, 0);
+
+#ifdef USE_SURFACE_BTREE
+  return g_tree_nnodes (s->faces);
+#else /* not USE_SURFACE_BTREE */
+  return g_hash_table_size (s->faces);
+#endif /* not USE_SURFACE_BTREE */
+}
+
+static void build_list_face (GtsTriangle * t, GSList ** list)
+{
+  *list = g_slist_prepend (*list, gts_bbox_triangle (gts_bbox_class (), t));
+}
+
+static void build_list_boundary (GtsEdge * e, GSList ** list)
+{
+  if (gts_edge_is_boundary (e, NULL))
+    *list = g_slist_prepend (*list, gts_bbox_segment (gts_bbox_class (),
+						      GTS_SEGMENT (e)));
+}
+
+/**
+ * gts_surface_distance:
+ * @s1: a #GtsSurface.
+ * @s2: a #GtsSurface.
+ * @delta: a spatial increment defined as the percentage of the diagonal
+ * of the bounding box of @s2.
+ * @face_range: a #GtsRange.
+ * @boundary_range: a #GtsRange.
+ *
+ * Using the gts_bb_tree_surface_distance() and
+ * gts_bb_tree_surface_boundary_distance() functions fills @face_range
+ * and @boundary_range with the min, max and average Euclidean
+ * (minimum) distances between the faces of @s1 and the faces of @s2
+ * and between the boundary edges of @s1 and @s2.  
+ */
+void gts_surface_distance (GtsSurface * s1, GtsSurface * s2, gdouble delta,
+			   GtsRange * face_range, GtsRange * boundary_range)
+{
+  GNode * face_tree, * boundary_tree;
+  GSList * bboxes;
+
+  g_return_if_fail (s1 != NULL);
+  g_return_if_fail (s2 != NULL);
+  g_return_if_fail (delta > 0. && delta < 1.);
+  g_return_if_fail (face_range != NULL);
+  g_return_if_fail (boundary_range != NULL);
+
+  bboxes = NULL;
+  gts_surface_foreach_face (s2, (GtsFunc) build_list_face, &bboxes);
+  if (bboxes != NULL) {
+    face_tree = gts_bb_tree_new (bboxes);
+    g_slist_free (bboxes);
+    
+    gts_bb_tree_surface_distance (face_tree, s1, 
+			       (GtsBBoxDistFunc) gts_point_triangle_distance,
+				  delta, face_range);
+    gts_bb_tree_destroy (face_tree, TRUE);
+    
+    bboxes = NULL;
+    gts_surface_foreach_edge (s2, (GtsFunc) build_list_boundary, &bboxes);
+    if (bboxes != NULL) {
+      boundary_tree = gts_bb_tree_new (bboxes);
+      g_slist_free (bboxes);
+
+      gts_bb_tree_surface_boundary_distance (boundary_tree,
+	       s1, 
+	       (GtsBBoxDistFunc) gts_point_segment_distance,
+	       delta, boundary_range);
+      gts_bb_tree_destroy (boundary_tree, TRUE);
+    }
+    else
+      gts_range_reset (boundary_range);
+  }
+  else {
+    gts_range_reset (face_range);
+    gts_range_reset (boundary_range);
+  }
+}
+
+static void surface_boundary (GtsEdge * e, gpointer * data)
+{
+  GSList ** list = data[0];
+
+  if (gts_edge_is_boundary (e, data[1]))
+    *list = g_slist_prepend (*list, e);
+}
+
+/**
+ * gts_surface_boundary:
+ * @surface: a #GtsSurface.
+ *
+ * Returns: a list of #GtsEdge boundary of @surface.
+ */
+GSList * gts_surface_boundary (GtsSurface * surface)
+{
+  GSList * list = NULL;
+  gpointer data[2];
+
+  g_return_val_if_fail (surface != NULL, NULL);
+
+  data[0] = &list;
+  data[1] = surface;
+  gts_surface_foreach_edge (surface, (GtsFunc) surface_boundary, data);
+  
+  return list;
+}
+
+struct _GtsSurfaceTraverse {
+  GtsFifo * q;
+  GtsSurface * s;
+};
+
+/**
+ * gts_surface_traverse_new:
+ * @s: a #GtsSurface.
+ * @f: a #GtsFace belonging to @s.
+ *
+ * Returns: a new #GtsSurfaceTraverse, initialized to start traversing
+ * from face @f of surface @s.  
+ */
+GtsSurfaceTraverse * gts_surface_traverse_new (GtsSurface * s,
+					       GtsFace * f)
+{
+  GtsSurfaceTraverse * t;
+
+  g_return_val_if_fail (s != NULL, NULL);
+  g_return_val_if_fail (f != NULL, NULL);
+  g_return_val_if_fail (gts_face_has_parent_surface (f, s), NULL);
+  
+  t = g_malloc (sizeof (GtsSurfaceTraverse));
+  t->q = gts_fifo_new ();
+  t->s = s;
+  GTS_OBJECT (f)->reserved = GUINT_TO_POINTER (1);
+  gts_fifo_push (t->q, f);
+  return t;
+}
+
+static void push_neighbor (GtsFace * v, gpointer * data)
+{
+  if (!GTS_OBJECT (v)->reserved) {
+    GTS_OBJECT (v)->reserved = 
+      GUINT_TO_POINTER (GPOINTER_TO_UINT (GTS_OBJECT (data[1])->reserved) + 1);
+    gts_fifo_push (data[0], v);
+  }
+}
+
+/**
+ * gts_surface_traverse_next:
+ * @t: a #GtsSurfaceTraverse.
+ * @level: a pointer to a guint or %NULL.
+ *
+ * Returns: the next face of the traversal in breadth-first order or
+ * %NULL if no faces are left. If @level if not %NULL, it is filled
+ * with the level of the returned face (0 for the initial face, 1 for
+ * its neighbors and so on).  
+ */
+GtsFace * gts_surface_traverse_next (GtsSurfaceTraverse * t,
+				     guint * level)
+{
+  GtsFace * u;
+
+  g_return_val_if_fail (t != NULL, NULL);
+
+  u = gts_fifo_pop (t->q);
+  if (u) {
+    gpointer data[2];
+
+    if (level)
+      *level = GPOINTER_TO_UINT (GTS_OBJECT (u)->reserved);
+    data[0] = t->q;
+    data[1] = u;
+    gts_face_foreach_neighbor (u, t->s, (GtsFunc) push_neighbor, data);
+  }
+  return u;
+}
+
+/**
+ * gts_surface_traverse_destroy:
+ * @t: a #GtsSurfaceTraverse.
+ *
+ * Frees all the memory allocated for @t.
+ */
+void gts_surface_traverse_destroy (GtsSurfaceTraverse * t)
+{
+  g_return_if_fail (t != NULL);
+
+  gts_surface_foreach_face (t->s, (GtsFunc) gts_object_reset_reserved, NULL);
+  gts_fifo_destroy (t->q);
+  g_free (t);
+}
+
+static void traverse_manifold (GtsTriangle * t, GtsSurface * s)
+{
+  if (g_slist_length (GTS_FACE (t)->surfaces) > 1)
+    return;
+
+  gts_surface_add_face (s, GTS_FACE (t));
+  if (g_slist_length (t->e1->triangles) == 2) {
+    if (t->e1->triangles->data != t)
+      traverse_manifold (t->e1->triangles->data, s);
+    else
+      traverse_manifold (t->e1->triangles->next->data, s);
+  }
+  if (g_slist_length (t->e2->triangles) == 2) {
+    if (t->e2->triangles->data != t)
+      traverse_manifold (t->e2->triangles->data, s);
+    else
+      traverse_manifold (t->e2->triangles->next->data, s);
+  }
+  if (g_slist_length (t->e3->triangles) == 2) {
+    if (t->e3->triangles->data != t)
+      traverse_manifold (t->e3->triangles->data, s);
+    else
+      traverse_manifold (t->e3->triangles->next->data, s);
+  }
+}
+
+static void non_manifold_edges (GtsEdge * e, gpointer * data)
+{
+  GtsSurface * s = data[0];
+  GSList ** non_manifold = data[1];
+
+  if (gts_edge_face_number (e, s) > 2) {
+    GSList * i = e->triangles;
+
+    while (i) {
+      if (gts_face_has_parent_surface (i->data, s) &&
+	  !g_slist_find (*non_manifold, i->data))
+	*non_manifold = g_slist_prepend (*non_manifold, i->data);
+      i = i->next;
+    }
+  }
+}
+
+static void traverse_boundary (GtsEdge * e, gpointer * data)
+{
+  GtsSurface * orig = data[0];
+  GSList ** components = data[1];
+  GtsFace * f = gts_edge_is_boundary (e, orig);
+
+  if (f != NULL && g_slist_length (f->surfaces) == 1) {
+    GtsSurface * s = 
+      gts_surface_new (GTS_SURFACE_CLASS (GTS_OBJECT (orig)->klass),
+		       orig->face_class,
+		       orig->edge_class,
+		       orig->vertex_class);
+    GSList * non_manifold = NULL, * i;
+    gpointer data[2];
+
+    *components = g_slist_prepend (*components, s);
+    data[0] = s;
+    data[1] = &non_manifold;
+    traverse_manifold (GTS_TRIANGLE (f), s);
+
+    gts_surface_foreach_edge (s, (GtsFunc) non_manifold_edges, data);
+    i = non_manifold;
+    while (i) {
+      gts_surface_remove_face (s, i->data);
+      i = i->next;
+    }
+    g_slist_free (non_manifold);
+  }
+}
+
+static void traverse_remaining (GtsFace * f, gpointer * data)
+{
+  GtsSurface * orig = data[0];
+  GSList ** components = data[1];
+
+  if (g_slist_length (f->surfaces) == 1) {
+    GtsSurface * s = 
+      gts_surface_new (GTS_SURFACE_CLASS (GTS_OBJECT (orig)->klass),
+		       orig->face_class,
+		       orig->edge_class,
+		       orig->vertex_class);
+    GSList * non_manifold = NULL, * i;
+    gpointer data[2];
+
+    *components = g_slist_prepend (*components, s);
+    data[0] = s;
+    data[1] = &non_manifold;
+    traverse_manifold (GTS_TRIANGLE (f), s);
+
+    gts_surface_foreach_edge (s, (GtsFunc) non_manifold_edges, data);
+    i = non_manifold;
+    while (i) {
+      gts_surface_remove_face (s, i->data);
+      i = i->next;
+    }
+    g_slist_free (non_manifold);
+  }
+}
+
+/**
+ * gts_surface_split:
+ * @s: a #GtsSurface.
+ *
+ * Splits a surface into connected and manifold components.
+ * 
+ * Returns: a list of new #GtsSurface.
+ */
+GSList * gts_surface_split (GtsSurface * s)
+{
+  gpointer data[2];
+  GSList * components = NULL;
+
+  g_return_val_if_fail (s != NULL, NULL);
+
+  data[0] = s;
+  data[1] = &components;
+
+  /* boundary components */
+  gts_surface_foreach_edge (s, (GtsFunc) traverse_boundary, data);
+
+  /* remaining components */
+  gts_surface_foreach_face (s, (GtsFunc) traverse_remaining, data);
+
+  return components;
+}
diff --git a/gts/triangle.c b/gts/triangle.c
new file mode 100644
index 0000000..5213a51
--- /dev/null
+++ b/gts/triangle.c
@@ -0,0 +1,1094 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <math.h>
+#include "gts.h"
+
+static void triangle_destroy (GtsObject * object)
+{
+  GtsTriangle * triangle = GTS_TRIANGLE (object);
+  GtsEdge * e1 = triangle->e1;
+  GtsEdge * e2 = triangle->e2;
+  GtsEdge * e3 = triangle->e3;
+
+  e1->triangles = g_slist_remove (e1->triangles, triangle);
+  if (!GTS_OBJECT_DESTROYED (e1) &&
+      !gts_allow_floating_edges && e1->triangles == NULL)
+    gts_object_destroy (GTS_OBJECT (e1));
+  
+  e2->triangles = g_slist_remove (e2->triangles, triangle);
+  if (!GTS_OBJECT_DESTROYED (e2) &&
+      !gts_allow_floating_edges && e2->triangles == NULL)
+    gts_object_destroy (GTS_OBJECT (e2));
+  
+  e3->triangles = g_slist_remove (e3->triangles, triangle);
+  if (!GTS_OBJECT_DESTROYED (e3) &&
+      !gts_allow_floating_edges && e3->triangles == NULL)
+    gts_object_destroy (GTS_OBJECT (e3));
+
+  (* GTS_OBJECT_CLASS (gts_triangle_class ())->parent_class->destroy) (object);
+}
+
+static void triangle_class_init (GtsObjectClass * klass)
+{
+  klass->destroy = triangle_destroy;
+}
+
+static void triangle_init (GtsTriangle * triangle)
+{
+  triangle->e1 = triangle->e2 = triangle->e3 = NULL;
+}
+
+/**
+ * gts_triangle_class:
+ *
+ * Returns: the #GtsTriangleClass.
+ */
+GtsTriangleClass * gts_triangle_class (void)
+{
+  static GtsTriangleClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo triangle_info = {
+      "GtsTriangle",
+      sizeof (GtsTriangle),
+      sizeof (GtsTriangleClass),
+      (GtsObjectClassInitFunc) triangle_class_init,
+      (GtsObjectInitFunc) triangle_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (gts_object_class (), 
+				  &triangle_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_triangle_set:
+ * @triangle: a #GtsTriangle.
+ * @e1: a #GtsEdge.
+ * @e2: another #GtsEdge touching @e1.
+ * @e3: another #GtsEdge touching both @e1 and @e2.
+ *
+ * Sets the edge of @triangle to @e1, @e2 and @e3 while checking that they
+ * define a valid triangle.
+ */
+void gts_triangle_set (GtsTriangle * triangle, 
+		       GtsEdge * e1, 
+		       GtsEdge * e2,
+		       GtsEdge * e3)
+{
+  g_return_if_fail (e1 != NULL);
+  g_return_if_fail (e2 != NULL);
+  g_return_if_fail (e3 != NULL);
+  g_return_if_fail (e1 != e2 && e1 != e3 && e2 != e3);
+
+  triangle->e1 = e1;
+  triangle->e2 = e2;
+  triangle->e3 = e3;
+
+  if (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e2)->v1)
+    g_return_if_fail (gts_segment_connect (GTS_SEGMENT (e3), 
+					   GTS_SEGMENT (e1)->v2, 
+					   GTS_SEGMENT (e2)->v2));
+  else if (GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v1)
+    g_return_if_fail (gts_segment_connect (GTS_SEGMENT (e3), 
+					   GTS_SEGMENT (e1)->v1, 
+					   GTS_SEGMENT (e2)->v2));
+  else if (GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v2)
+    g_return_if_fail (gts_segment_connect (GTS_SEGMENT (e3), 
+					   GTS_SEGMENT (e1)->v1, 
+					   GTS_SEGMENT (e2)->v1));
+  else if (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e2)->v2)
+    g_return_if_fail (gts_segment_connect (GTS_SEGMENT (e3), 
+					   GTS_SEGMENT (e1)->v2, 
+					   GTS_SEGMENT (e2)->v1));
+  else
+    g_assert_not_reached ();
+
+  e1->triangles = g_slist_prepend (e1->triangles, triangle);
+  e2->triangles = g_slist_prepend (e2->triangles, triangle);
+  e3->triangles = g_slist_prepend (e3->triangles, triangle);
+}
+
+/**
+ * gts_triangle_new:
+ * @klass: a #GtsTriangleClass.
+ * @e1: a #GtsEdge.
+ * @e2: another #GtsEdge touching @e1.
+ * @e3: another #GtsEdge touching both @e1 and @e2.
+ *
+ * Returns: a new #GtsTriangle having @e1, @e2 and @e3 as edges.
+ */
+GtsTriangle * gts_triangle_new (GtsTriangleClass * klass,
+				GtsEdge * e1,
+				GtsEdge * e2,
+				GtsEdge * e3)
+{
+  GtsTriangle * t;
+
+  t = GTS_TRIANGLE (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  gts_triangle_set (t, e1, e2, e3);
+  
+  return t;
+}
+
+/**
+ * gts_triangle_vertex_opposite:
+ * @t: a #GtsTriangle.
+ * @e: a #GtsEdge used by @t.
+ *
+ * This function fails if @e is not an edge of @t.
+ * 
+ * Returns: a #GtsVertex, vertex of @t which does not belong to @e.
+ */
+GtsVertex * gts_triangle_vertex_opposite (GtsTriangle * t, GtsEdge * e)
+{
+  g_return_val_if_fail (t != NULL, NULL);
+  g_return_val_if_fail (e != NULL, NULL);
+
+  if (t->e1 == e) {
+    GtsVertex * v = GTS_SEGMENT (t->e2)->v1;
+    if (v != GTS_SEGMENT (e)->v1 && v != GTS_SEGMENT (e)->v2)
+      return v;
+    return GTS_SEGMENT (t->e2)->v2;
+  }
+  if (t->e2 == e) {
+    GtsVertex * v = GTS_SEGMENT (t->e1)->v1;
+    if (v != GTS_SEGMENT (e)->v1 && v != GTS_SEGMENT (e)->v2)
+      return v;
+    return GTS_SEGMENT (t->e1)->v2;
+  }
+  if (t->e3 == e) {
+    GtsVertex * v = GTS_SEGMENT (t->e2)->v1;
+    if (v != GTS_SEGMENT (e)->v1 && v != GTS_SEGMENT (e)->v2)
+      return v;
+    return GTS_SEGMENT (t->e2)->v2;
+  }
+  g_assert_not_reached ();
+  return NULL;
+}
+
+/**
+ * gts_triangle_edge_opposite:
+ * @t: a #GtsTriangle.
+ * @v: a #GtsVertex of @t.
+ *
+ * Returns: the edge of @t opposite @v or %NULL if @v is not a vertice of @t.
+ */
+GtsEdge * gts_triangle_edge_opposite (GtsTriangle * t, GtsVertex * v)
+{
+  GtsSegment * s1, * s2, * s3;
+
+  g_return_val_if_fail (t != NULL, NULL);
+  g_return_val_if_fail (v != NULL, NULL);
+
+  s1 = GTS_SEGMENT (t->e1);
+  s2 = GTS_SEGMENT (t->e2);
+
+  if (s1->v1 != v && s1->v2 != v) {
+    if (s2->v1 != v && s2->v2 != v)
+      return NULL;
+    return t->e1;
+  }
+  if (s2->v1 != v && s2->v2 != v)
+    return t->e2;
+  s3 = GTS_SEGMENT (t->e3);
+  g_assert (s3->v1 != v && s3->v2 != v);
+  return t->e3;
+}
+
+/**
+ * gts_triangles_angle:
+ * @t1: a #GtsTriangle.
+ * @t2: a #GtsTriangle.
+ *
+ * Returns: the value (in radians) of the angle between @t1 and @t2.
+ */
+gdouble gts_triangles_angle (GtsTriangle * t1,
+			     GtsTriangle * t2)
+{
+  gdouble nx1, ny1, nz1, nx2, ny2, nz2;
+  gdouble pvx, pvy, pvz;
+  gdouble theta;
+
+  g_return_val_if_fail (t1 != NULL && t2 != NULL, 0.0);
+
+  gts_triangle_normal (t1, &nx1, &ny1, &nz1);
+  gts_triangle_normal (t2, &nx2, &ny2, &nz2);
+
+  pvx = ny1*nz2 - nz1*ny2;
+  pvy = nz1*nx2 - nx1*nz2;
+  pvz = nx1*ny2 - ny1*nx2;
+
+  theta = atan2 (sqrt (pvx*pvx + pvy*pvy + pvz*pvz), 
+		 nx1*nx2 + ny1*ny2 + nz1*nz2) - M_PI;
+  return theta < - M_PI ? theta + 2.*M_PI : theta;
+}
+
+/**
+ * gts_triangles_are_compatible:
+ * @t1: a #GtsTriangle.
+ * @t2: a #GtsTriangle.
+ * @e: a #GtsEdge used by both @t1 and @t2.
+ *
+ * Checks if @t1 and @t2 have compatible orientations i.e. if @t1 and
+ * @t2 can be part of the same surface without conflict in the surface
+ * normal orientation.
+ *
+ * Returns: %TRUE if @t1 and @t2 are compatible, %FALSE otherwise.
+ */
+gboolean gts_triangles_are_compatible (GtsTriangle * t1, 
+				       GtsTriangle * t2,
+				       GtsEdge * e)
+{
+  GtsEdge * e1 = NULL, * e2 = NULL;
+
+  g_return_val_if_fail (t1 != NULL, FALSE);
+  g_return_val_if_fail (t2 != NULL, FALSE);
+  g_return_val_if_fail (e != NULL, FALSE);
+
+  if (t1->e1 == e) e1 = t1->e2;
+  else if (t1->e2 == e) e1 = t1->e3;
+  else if (t1->e3 == e) e1 = t1->e1;
+  else
+    g_assert_not_reached ();
+  if (t2->e1 == e) e2 = t2->e2;
+  else if (t2->e2 == e) e2 = t2->e3;
+  else if (t2->e3 == e) e2 = t2->e1;
+  else
+    g_assert_not_reached ();
+  if (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e2)->v1 || 
+      GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e2)->v2 || 
+      GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v1 || 
+      GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v2)
+    return FALSE;
+  return TRUE;
+}
+
+/**
+ * gts_triangle_area:
+ * @t: a #GtsTriangle.
+ *
+ * Returns: the area of the triangle @t.
+ */
+gdouble gts_triangle_area (GtsTriangle * t)
+{
+  gdouble x, y, z;
+  
+  g_return_val_if_fail (t != NULL, 0.0);
+  
+  gts_triangle_normal (t, &x, &y, &z);
+  
+  return sqrt (x*x + y*y + z*z)/2.;
+}
+
+/**
+ * gts_triangle_perimeter:
+ * @t: a #GtsTriangle.
+ *
+ * Returns: the perimeter of the triangle @t.
+ */
+gdouble gts_triangle_perimeter (GtsTriangle * t)
+{
+  GtsVertex * v;
+
+  g_return_val_if_fail (t != NULL, 0.0);
+
+  v = gts_triangle_vertex (t);
+  return 
+    gts_point_distance (GTS_POINT (GTS_SEGMENT (t->e1)->v1), 
+			GTS_POINT (GTS_SEGMENT (t->e1)->v2)) +
+    gts_point_distance (GTS_POINT (GTS_SEGMENT (t->e1)->v1), 
+			GTS_POINT (v)) +
+    gts_point_distance (GTS_POINT (GTS_SEGMENT (t->e1)->v2), 
+			GTS_POINT (v));
+}
+
+/* perimeter of the equilateral triangle of area unity */
+#define GOLDEN_PERIMETER 4.5590141139 
+
+/**
+ * gts_triangle_quality:
+ * @t: a #GtsTriangle.
+ *
+ * The quality of a triangle is defined as the ratio of the square
+ * root of its surface area to its perimeter relative to this same
+ * ratio for an equilateral triangle with the same area. The quality
+ * is then one for an equilateral triangle and tends to zero for a
+ * very stretched triangle.
+ *
+ * Returns: the quality of the triangle @t.
+ */
+gdouble gts_triangle_quality (GtsTriangle * t)
+{
+  gdouble perimeter;
+
+  g_return_val_if_fail (t != NULL, 0.0);
+
+  perimeter = gts_triangle_perimeter (t);
+  return perimeter > 0.0 ?
+    GOLDEN_PERIMETER*sqrt (gts_triangle_area (t))/perimeter :
+    0.0;
+}
+
+/**
+ * gts_triangle_normal:
+ * @t: a #GtsTriangle.
+ * @x: the x coordinate of the normal.
+ * @y: the y coordinate of the normal.
+ * @z: the z coordinate of the normal.
+ *
+ * Computes the coordinates of the oriented normal of @t as the
+ * cross-product of two edges, using the left-hand rule. The normal is
+ * not normalized.  If this triangle is part of a closed and oriented
+ * surface, the normal points to the outside of the surface.  
+ */
+void gts_triangle_normal (GtsTriangle * t, 
+			  gdouble * x, 
+			  gdouble * y, 
+			  gdouble * z)
+{
+  GtsVertex * v1, * v2 = NULL, * v3 = NULL;
+  GtsPoint * p1, * p2, * p3;
+  gdouble x1, y1, z1, x2, y2, z2;
+
+  g_return_if_fail (t != NULL);
+
+  v1 = GTS_SEGMENT (t->e1)->v1;
+  if (GTS_SEGMENT (t->e1)->v1 == GTS_SEGMENT (t->e2)->v1) {
+    v2 = GTS_SEGMENT (t->e2)->v2;
+    v3 = GTS_SEGMENT (t->e1)->v2;
+  }
+  else if (GTS_SEGMENT (t->e1)->v2 == GTS_SEGMENT (t->e2)->v2) {
+    v2 = GTS_SEGMENT (t->e1)->v2;
+    v3 = GTS_SEGMENT (t->e2)->v1;
+  }
+  else if (GTS_SEGMENT (t->e1)->v1 == GTS_SEGMENT (t->e2)->v2) {
+    v2 = GTS_SEGMENT (t->e2)->v1;
+    v3 = GTS_SEGMENT (t->e1)->v2;
+  }
+  else if (GTS_SEGMENT (t->e1)->v2 == GTS_SEGMENT (t->e2)->v1) {
+    v2 = GTS_SEGMENT (t->e1)->v2;
+    v3 = GTS_SEGMENT (t->e2)->v2;
+  }
+  else {
+    fprintf (stderr, "t: %p t->e1: %p t->e2: %p t->e3: %p t->e1->v1: %p t->e1->v2: %p t->e2->v1: %p t->e2->v2: %p t->e3->v1: %p t->e3->v2: %p\n",
+	 t, t->e1, t->e2, 
+	 t->e3, GTS_SEGMENT (t->e1)->v1, GTS_SEGMENT (t->e1)->v2, 
+	 GTS_SEGMENT (t->e2)->v1, GTS_SEGMENT (t->e2)->v2, 
+	 GTS_SEGMENT (t->e3)->v1, GTS_SEGMENT (t->e3)->v2);
+    g_assert_not_reached ();
+  }
+
+  p1 = GTS_POINT (v1);
+  p2 = GTS_POINT (v2);
+  p3 = GTS_POINT (v3);
+
+  x1 = p2->x - p1->x;
+  y1 = p2->y - p1->y;
+  z1 = p2->z - p1->z;
+
+  x2 = p3->x - p1->x;
+  y2 = p3->y - p1->y;
+  z2 = p3->z - p1->z;
+
+  *x = y1*z2 - z1*y2;
+  *y = z1*x2 - x1*z2;
+  *z = x1*y2 - y1*x2;
+}
+
+/**
+ * gts_triangle_orientation:
+ * @t: a #GtsTriangle.
+ * 
+ * Checks for the orientation of the plane (x,y) projection of a
+ * triangle. See gts_point_orientation() for details. This function
+ * is geometrically robust.
+ *
+ * Returns: a number depending on the orientation of the vertices of @t.
+ */
+gdouble gts_triangle_orientation (GtsTriangle * t)
+{
+  GtsVertex * v1, * v2 = NULL, * v3 = NULL;
+
+  g_return_val_if_fail (t != NULL, 0.0);
+
+  v1 = GTS_SEGMENT (t->e1)->v1;
+  if (GTS_SEGMENT (t->e1)->v1 == GTS_SEGMENT (t->e2)->v1) {
+    v2 = GTS_SEGMENT (t->e2)->v2;
+    v3 = GTS_SEGMENT (t->e1)->v2;
+  }
+  else if (GTS_SEGMENT (t->e1)->v2 == GTS_SEGMENT (t->e2)->v2) {
+    v2 = GTS_SEGMENT (t->e1)->v2;
+    v3 = GTS_SEGMENT (t->e2)->v1;
+  }
+  else if (GTS_SEGMENT (t->e1)->v1 == GTS_SEGMENT (t->e2)->v2) {
+    v2 = GTS_SEGMENT (t->e2)->v1;
+    v3 = GTS_SEGMENT (t->e1)->v2;
+  }
+  else if (GTS_SEGMENT (t->e1)->v2 == GTS_SEGMENT (t->e2)->v1) {
+    v2 = GTS_SEGMENT (t->e1)->v2;
+    v3 = GTS_SEGMENT (t->e2)->v2;
+  }
+  else
+    g_assert_not_reached ();
+  return gts_point_orientation (GTS_POINT (v1), 
+				GTS_POINT (v2), 
+				GTS_POINT (v3));
+}
+
+/**
+ * gts_triangle_revert:
+ * @t: a #GtsTriangle.
+ * 
+ * Changes the orientation of triangle @t, turning it inside out.
+ */
+void gts_triangle_revert (GtsTriangle * t)
+{
+  GtsEdge * e;
+
+  g_return_if_fail (t != NULL);
+
+  e = t->e1;
+  t->e1 = t->e2;
+  t->e2 = e;
+}
+
+/**
+ * gts_triangles_from_edges:
+ * @edges: a list of #GtsEdge.
+ *
+ * Builds a list of unique triangles which have one of their edges in @edges.
+ * 
+ * Returns: the list of triangles.
+ */
+GSList * gts_triangles_from_edges (GSList * edges)
+{
+  GHashTable * hash;
+  GSList * triangles = NULL, * i;
+
+  hash = g_hash_table_new (NULL, NULL);
+  i = edges;
+  while (i) {
+    GSList * j = GTS_EDGE (i->data)->triangles;
+    while (j) {
+      GtsTriangle * t = j->data;
+      if (g_hash_table_lookup (hash, t) == NULL) {
+	triangles = g_slist_prepend (triangles, t);
+	g_hash_table_insert (hash, t, i);
+      }
+      j = j->next;
+    }
+    i = i->next;
+  }
+  g_hash_table_destroy (hash);
+
+  return triangles;
+}
+
+/**
+ * gts_triangle_vertices_edges:
+ * @t: a #GtsTriangle.
+ * @e: a #GtsEdge belonging to the edges of @t or %NULL.
+ * @v1: a #GtsVertex used by @t.
+ * @v2: a #GtsVertex used by @t.
+ * @v3: a #GtsVertex used by @t.
+ * @e1: a #GtsEdge used by @t.
+ * @e2: a #GtsEdge used by @t.
+ * @e3: a #GtsEdge used by @t.
+ *
+ * Given @t and @e, returns @v1, @v2, @v3, @e1, @e2 and @e3. @e1
+ * has @v1 and @v2 as vertices, @e2 has @v2 and @v3 as vertices
+ * and @e3 has @v3 and @v1 as vertices. @v1, @v2 and @v3 respects
+ * the orientation of @t. If @e is not NULL, @e1 and @e are
+ * identical.
+ */
+void gts_triangle_vertices_edges (GtsTriangle * t, 
+				  GtsEdge * e,
+				  GtsVertex ** v1, 
+				  GtsVertex ** v2, 
+				  GtsVertex ** v3,
+				  GtsEdge ** e1,
+				  GtsEdge ** e2,
+				  GtsEdge ** e3)
+{
+  GtsEdge * ee1, * ee2;
+
+  g_return_if_fail (t != NULL);
+  
+  if (e == t->e1 || e == NULL) {
+    *e1 = ee1 = t->e1; *e2 = ee2 = t->e2; *e3 = t->e3;    
+  }
+  else if (e == t->e2) {
+    *e1 = ee1 = e; *e2 = ee2 = t->e3; *e3 = t->e1;
+  }
+  else if (e == t->e3) {
+    *e1 = ee1 = e; *e2 = ee2 = t->e1; *e3 = t->e2;
+  }
+  else {
+    g_assert_not_reached ();
+    ee1 = ee2 = NULL; /* to avoid complaints from the compiler */
+  }
+  if (GTS_SEGMENT (ee1)->v2 == GTS_SEGMENT (ee2)->v1) {
+    *v1 = GTS_SEGMENT (ee1)->v1; 
+    *v2 = GTS_SEGMENT (ee1)->v2; 
+    *v3 = GTS_SEGMENT (ee2)->v2;
+  }
+  else if (GTS_SEGMENT (ee1)->v2 == GTS_SEGMENT (ee2)->v2) {
+    *v1 = GTS_SEGMENT (ee1)->v1; 
+    *v2 = GTS_SEGMENT (ee1)->v2; 
+    *v3 = GTS_SEGMENT (ee2)->v1;
+  }
+  else if (GTS_SEGMENT (ee1)->v1 == GTS_SEGMENT (ee2)->v1) {
+    *v1 = GTS_SEGMENT (ee1)->v2; 
+    *v2 = GTS_SEGMENT (ee1)->v1; 
+    *v3 = GTS_SEGMENT (ee2)->v2;
+  }
+  else if (GTS_SEGMENT (ee1)->v1 == GTS_SEGMENT (ee2)->v2) {
+    *v1 = GTS_SEGMENT (ee1)->v2; 
+    *v2 = GTS_SEGMENT (ee1)->v1; 
+    *v3 = GTS_SEGMENT (ee2)->v1;
+  }
+  else
+    g_assert_not_reached ();
+}
+
+/* sqrt(3) */
+#define SQRT3 1.73205080757
+
+/**
+ * gts_triangle_enclosing:
+ * @klass: the class of the new triangle.
+ * @points: a list of #GtsPoint.
+ * @scale: a scaling factor (must be larger than one).
+ * 
+ * Builds a new triangle (including new vertices and edges) enclosing
+ * the plane projection of all the points in @points. This triangle is
+ * equilateral and encloses a rectangle defined by the maximum and
+ * minimum x and y coordinates of the points. @scale is an homothetic
+ * scaling factor. If equal to one, the triangle encloses exactly the
+ * enclosing rectangle.
+ * 
+ * Returns: a new #GtsTriangle.  
+ */
+GtsTriangle * gts_triangle_enclosing (GtsTriangleClass * klass,
+				      GSList * points, gdouble scale)
+{
+  gdouble xmax, xmin, ymax, ymin;
+  gdouble xo, yo, r;
+  GtsVertex * v1, * v2, * v3;
+  GtsEdge * e1, * e2, * e3;
+
+  if (points == NULL)
+    return NULL;
+  
+  xmax = xmin = GTS_POINT (points->data)->x;
+  ymax = ymin = GTS_POINT (points->data)->y;
+  points = points->next;
+  while (points) {
+    GtsPoint * p = points->data;
+    if (p->x > xmax) xmax = p->x;
+    else if (p->x < xmin) xmin = p->x;
+    if (p->y > ymax) ymax = p->y;
+    else if (p->y < ymin) ymin = p->y;    
+    points = points->next;
+  }
+  xo = (xmax + xmin)/2.;
+  yo = (ymax + ymin)/2.;
+  r = scale*sqrt((xmax - xo)*(xmax - xo) + (ymax - yo)*(ymax - yo));
+  if (r == 0.0) r = scale;
+  v1 = gts_vertex_new (gts_vertex_class (),
+		       xo + r*SQRT3, yo - r, 0.0);
+  v2 = gts_vertex_new (gts_vertex_class (),
+		       xo, yo + 2.*r, 0.0);
+  v3 = gts_vertex_new (gts_vertex_class (),
+		       xo - r*SQRT3, yo - r, 0.0);
+  e1 = gts_edge_new (gts_edge_class (), v1, v2);
+  e2 = gts_edge_new (gts_edge_class (), v2, v3);
+  e3 = gts_edge_new (gts_edge_class (), v3, v1);
+  return gts_triangle_new (gts_triangle_class (), e1, e2, e3);
+}
+
+/**
+ * gts_triangle_neighbor_number:
+ * @t: a #GtsTriangle.
+ *
+ * Returns: the number of triangles neighbors of @t.
+ */
+guint gts_triangle_neighbor_number (GtsTriangle * t)
+{
+  GSList * i;
+  guint nn = 0;
+  GtsEdge * ee[4], ** e = ee;
+  
+  g_return_val_if_fail (t != NULL, 0);
+
+  ee[0] = t->e1; ee[1] = t->e2; ee[2] = t->e3; ee[3] = NULL;
+  while (*e) {
+    i = (*e++)->triangles;
+    while (i) {
+      GtsTriangle * t1 = i->data;
+      if (t1 != t)
+	nn++;
+      i = i->next;
+    }
+  }
+  return nn;
+}
+
+/**
+ * gts_triangle_neighbors:
+ * @t: a #GtsTriangle.
+ *
+ * Returns: a list of #GtsTriangle neighbors of @t.
+ */
+GSList * gts_triangle_neighbors (GtsTriangle * t)
+{
+  GSList * i, * list = NULL;
+  GtsEdge * ee[4], ** e = ee;
+  
+  g_return_val_if_fail (t != NULL, NULL);
+
+  ee[0] = t->e1; ee[1] = t->e2; ee[2] = t->e3; ee[3] = NULL;
+  while (*e) {
+    i = (*e++)->triangles;
+    while (i) {
+      GtsTriangle * t1 = i->data;
+      if (t1 != t)
+	list = g_slist_prepend (list, t1);
+      i = i->next;
+    }
+  }
+  return list;
+}
+
+/**
+ * gts_triangles_common_edge:
+ * @t1: a #GtsTriangle.
+ * @t2: a #GtsTriangle.
+ *
+ * Returns: a #GtsEdge common to both @t1 and @t2 or %NULL if @t1 and @t2
+ * do not share any edge.
+ */
+GtsEdge * gts_triangles_common_edge (GtsTriangle * t1,
+				     GtsTriangle * t2)
+{
+  g_return_val_if_fail (t1 != NULL, NULL);
+  g_return_val_if_fail (t2 != NULL, NULL);
+
+  if (t1->e1 == t2->e1 || t1->e1 == t2->e2 || t1->e1 == t2->e3)
+    return t1->e1;
+  if (t1->e2 == t2->e1 || t1->e2 == t2->e2 || t1->e2 == t2->e3)
+    return t1->e2;
+  if (t1->e3 == t2->e1 || t1->e3 == t2->e2 || t1->e3 == t2->e3)
+    return t1->e3;
+  return NULL;
+}
+
+/**
+ * gts_triangle_is_duplicate:
+ * @t: a #GtsTriangle.
+ *
+ * Returns: a #GtsTriangle different from @t but sharing all its edges 
+ * with @t or %NULL if there is none.
+ */
+GtsTriangle * gts_triangle_is_duplicate (GtsTriangle * t)
+{
+  GSList * i;
+  GtsEdge * e2, * e3;
+
+  g_return_val_if_fail (t != NULL, NULL);
+
+  e2 = t->e2;
+  e3 = t->e3;
+  i = t->e1->triangles;
+  while (i) {
+    GtsTriangle * t1 = i->data;
+    if (t1 != t && 
+	(t1->e1 == e2 || t1->e2 == e2 || t1->e3 == e2) &&
+	(t1->e1 == e3 || t1->e2 == e3 || t1->e3 == e3))
+      return t1;
+    i = i->next;
+  }
+  
+  return NULL;
+}
+
+/**
+ * gts_triangle_use_edges:
+ * @e1: a #GtsEdge.
+ * @e2: a #GtsEdge.
+ * @e3: a #GtsEdge.
+ *
+ * Returns: a #GtsTriangle having @e1, @e2 and @e3 as edges or %NULL if @e1,
+ * @e2 and @e3 are not part of any triangle.
+ */
+GtsTriangle * gts_triangle_use_edges (GtsEdge * e1,
+				      GtsEdge * e2,
+				      GtsEdge * e3)
+{
+  GSList * i;
+  
+  g_return_val_if_fail (e1 != NULL, NULL);
+  g_return_val_if_fail (e2 != NULL, NULL);
+  g_return_val_if_fail (e3 != NULL, NULL);
+
+  i = e1->triangles;
+  while (i) {
+    GtsTriangle * t = i->data;
+    if ((t->e1 == e2 && (t->e2 == e3 || t->e3 == e3)) ||
+	(t->e2 == e2 && (t->e1 == e3 || t->e3 == e3)) ||
+	(t->e3 == e2 && (t->e1 == e3 || t->e2 == e3)))
+      return t;
+    i = i->next;
+  }
+  
+  return NULL;
+}
+
+/**
+ * gts_triangle_is_ok:
+ * @t: a #GtsTriangle.
+ *
+ * Returns: %TRUE if @t is a non-degenerate, non-duplicate triangle,
+ * %FALSE otherwise.
+ */
+gboolean gts_triangle_is_ok (GtsTriangle * t)
+{
+  g_return_val_if_fail (t != NULL, FALSE);
+  g_return_val_if_fail (t->e1 != NULL, FALSE);
+  g_return_val_if_fail (t->e2 != NULL, FALSE);
+  g_return_val_if_fail (t->e3 != NULL, FALSE);
+  g_return_val_if_fail (t->e1 != t->e2 && t->e1 != t->e3 && t->e2 != t->e3, 
+			FALSE);
+  g_return_val_if_fail (gts_segments_touch (GTS_SEGMENT (t->e1), 
+					    GTS_SEGMENT (t->e2)),
+			FALSE);
+  g_return_val_if_fail (gts_segments_touch (GTS_SEGMENT (t->e1), 
+					    GTS_SEGMENT (t->e3)), 
+			FALSE);
+  g_return_val_if_fail (gts_segments_touch (GTS_SEGMENT (t->e2), 
+					    GTS_SEGMENT (t->e3)), 
+			FALSE);
+  g_return_val_if_fail (GTS_SEGMENT (t->e1)->v1 != GTS_SEGMENT (t->e1)->v2, 
+			FALSE);
+  g_return_val_if_fail (GTS_SEGMENT (t->e2)->v1 != GTS_SEGMENT (t->e2)->v2, 
+			FALSE);
+  g_return_val_if_fail (GTS_SEGMENT (t->e3)->v1 != GTS_SEGMENT (t->e3)->v2, 
+			FALSE);
+  g_return_val_if_fail (GTS_OBJECT (t)->reserved == NULL, FALSE);
+  g_return_val_if_fail (!gts_triangle_is_duplicate (t), FALSE);
+  return TRUE;
+}
+
+/**
+ * gts_triangle_vertices:
+ * @t: a #GtsTriangle.
+ * @v1: a pointer on a #GtsVertex.
+ * @v2: a pointer on a #GtsVertex.
+ * @v3: a pointer on a #GtsVertex.
+ *
+ * Fills @v1, @v2 and @v3 with the oriented set of vertices, summits of @t.
+ */
+void gts_triangle_vertices (GtsTriangle * t,
+			    GtsVertex ** v1, GtsVertex ** v2, GtsVertex ** v3)
+{
+  GtsSegment * e1, * e2;
+
+  g_return_if_fail (t != NULL);
+  g_return_if_fail (v1 != NULL && v2 != NULL && v3 != NULL);
+
+  e1 = GTS_SEGMENT (t->e1);
+  e2 = GTS_SEGMENT (t->e2);
+
+  if (GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v1) {
+    *v1 = GTS_SEGMENT (e1)->v1; 
+    *v2 = GTS_SEGMENT (e1)->v2; 
+    *v3 = GTS_SEGMENT (e2)->v2;
+  }
+  else if (GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v2) {
+    *v1 = GTS_SEGMENT (e1)->v1; 
+    *v2 = GTS_SEGMENT (e1)->v2; 
+    *v3 = GTS_SEGMENT (e2)->v1;
+  }
+  else if (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e2)->v1) {
+    *v1 = GTS_SEGMENT (e1)->v2; 
+    *v2 = GTS_SEGMENT (e1)->v1; 
+    *v3 = GTS_SEGMENT (e2)->v2;
+  }
+  else {
+    *v1 = GTS_SEGMENT (e1)->v2; 
+    *v2 = GTS_SEGMENT (e1)->v1; 
+    *v3 = GTS_SEGMENT (e2)->v1;
+  }
+}
+
+/**
+ * gts_triangle_circumcircle_center:
+ * @t: a #GtsTriangle.
+ * @point_class: a #GtsPointClass.
+ *
+ * Returns: a new #GtsPoint, center of the circumscribing circle of @t or
+ * %NULL if the circumscribing circle is not defined.
+ */
+GtsPoint * gts_triangle_circumcircle_center (GtsTriangle * t,
+					     GtsPointClass * point_class)
+{
+  GtsVertex * v1, * v2, * v3;
+  gdouble xa, ya, xb, yb, xc, yc;
+  gdouble xd, yd, xe, ye;
+  gdouble xad, yad, xae, yae;
+  gdouble det;
+  
+  g_return_val_if_fail (t != NULL, NULL);
+  g_return_val_if_fail (point_class != NULL, NULL);
+
+  gts_triangle_vertices (t, &v1, &v2, &v3);
+
+  xa = GTS_POINT (v1)->x; ya = GTS_POINT (v1)->y;
+  xb = GTS_POINT (v2)->x; yb = GTS_POINT (v2)->y;
+  xc = GTS_POINT (v3)->x; yc = GTS_POINT (v3)->y;
+  xd = (xa + xb)/2.; yd = (ya + yb)/2.;
+  xe = (xa + xc)/2.; ye = (ya + yc)/2.;
+  xad = xd - xa; yad = yd - ya;
+  xae = xe - xa; yae = ye - ya;
+  det = xad*yae - xae*yad;
+  if (det == 0.)
+    return NULL;
+  return gts_point_new (point_class,
+			(yae*yad*(yd - ye) + xad*yae*xd - xae*yad*xe)/det,
+			-(xae*xad*(xd - xe) + yad*xae*yd - yae*xad*ye)/det,
+			0.);
+}
+
+/* square of the maximum area ratio admissible */
+#define AREA_RATIO_MAX2 1e8
+
+static gboolean points_are_folded (GtsPoint * A,
+				   GtsPoint * B,
+				   GtsPoint * C,
+				   GtsPoint * D,
+				   gdouble max)
+{
+  GtsVector AB, AC, AD;
+  GtsVector n1, n2;
+  gdouble nn1, nn2, n1n2;
+
+  gts_vector_init (AB, A, B);
+  gts_vector_init (AC, A, C);
+  gts_vector_init (AD, A, D);
+  gts_vector_cross (n1, AB, AC);
+  gts_vector_cross (n2, AD, AB);
+
+  nn1 = gts_vector_scalar (n1, n1);
+  nn2 = gts_vector_scalar (n2, n2);
+  if (nn1 >= AREA_RATIO_MAX2*nn2 || nn2 >= AREA_RATIO_MAX2*nn1)
+    return TRUE;
+  n1n2 = gts_vector_scalar (n1, n2);
+  if (n1n2 > 0.)
+    return FALSE;
+  if (n1n2*n1n2/(nn1*nn2) > max)
+    return TRUE;
+  return FALSE;
+}
+
+static GtsVertex * triangle_use_vertices (GtsTriangle * t,
+					  GtsVertex * A, 
+					  GtsVertex * B)
+{
+  GtsVertex 
+    * v1 = GTS_SEGMENT (t->e1)->v1, 
+    * v2 = GTS_SEGMENT (t->e1)->v2, 
+    * v3 = gts_triangle_vertex (t);
+
+  if (v1 == A) {
+    if (v2 == B)
+      return v3;
+    g_assert (v3 == B);
+    return v2;
+  }
+  if (v2 == A) {
+    if (v1 == B)
+      return v3;
+    g_assert (v3 == B);
+    return v1;
+  }
+  if (v3 == A) {
+    if (v1 == B)
+      return v2;
+    g_assert (v2 == B);
+    return v1;
+  }
+  g_assert_not_reached ();
+  return NULL;
+}
+
+/**
+ * gts_triangles_are_folded:
+ * @triangles: a list of #GtsTriangle.
+ * @A: a #GtsVertex.
+ * @B: another #GtsVertex.
+ * @max: the maximum value of the square of the cosine of the angle between
+ * two triangles.
+ *
+ * Given a list of triangles sharing @A and @B as vertices, checks if any
+ * two triangles in the list make an angle larger than a given value defined
+ * by @max.
+ * 
+ * Returns: %TRUE if any pair of triangles in @triangles makes an angle larger 
+ * than the maximum value, %FALSE otherwise.
+ */
+gboolean gts_triangles_are_folded (GSList * triangles,
+				   GtsVertex * A, GtsVertex * B,
+				   gdouble max)
+{
+  GSList * i;
+
+  g_return_val_if_fail (A != NULL, TRUE);
+  g_return_val_if_fail (B != NULL, TRUE);
+
+  i = triangles;
+  while (i) {
+    GtsVertex * C = triangle_use_vertices (i->data, A, B);
+    GSList * j = i->next;    
+    while (j) {
+      GtsVertex * D = triangle_use_vertices (j->data, A, B);
+      if (points_are_folded (GTS_POINT (A), 
+			     GTS_POINT (B), 
+			     GTS_POINT (C), 
+			     GTS_POINT (D), 
+			     max))
+	return TRUE;
+      j = j->next;
+    }
+    i = i->next;
+  }
+  return FALSE;
+}
+
+/**
+ * gts_triangle_is_stabbed:
+ * @t: a #GtsTriangle.
+ * @p: a #GtsPoint.
+ * @orientation: a pointer or %NULL.
+ *
+ * Returns: one of the vertices of @t, one of the edges of @t or @t if
+ * any of these are stabbed by the ray starting at @p (included) and
+ * ending at (@p->x, @p->y, +infty), %NULL otherwise. If the ray is
+ * contained in the plane of the triangle %NULL is also returned. If
+ * @orientation is not %NULL, it is set to the value of the
+ * orientation of @p relative to @t (as given by
+ * gts_point_orientation_3d()).  
+ */
+GtsObject * gts_triangle_is_stabbed (GtsTriangle * t, 
+				     GtsPoint * p,
+				     gdouble * orientation)
+{
+  GtsVertex * v1, * v2, * v3, * inverted = NULL;
+  GtsEdge * e1, * e2, * e3, * tmp;
+  gdouble o, o1, o2, o3;
+
+  g_return_val_if_fail (t != NULL, NULL);
+  g_return_val_if_fail (p != NULL, NULL);
+
+  gts_triangle_vertices_edges (t, NULL, &v1, &v2, &v3, &e1, &e2, &e3);
+  o = gts_point_orientation (GTS_POINT (v1), GTS_POINT (v2), GTS_POINT (v3));
+  if (o == 0.)
+    return NULL;
+  if (o < 0.) {
+    inverted = v1;
+    v1 = v2;
+    v2 = inverted;
+    tmp = e2;
+    e2 = e3;
+    e3 = tmp;
+  }
+  o = gts_point_orientation_3d (GTS_POINT (v1),
+				GTS_POINT (v2), 
+				GTS_POINT (v3), 
+				p);
+  if (o < 0.)
+    return NULL;
+  o1 = gts_point_orientation (GTS_POINT (v1), GTS_POINT (v2), p);
+  if (o1 < 0.)
+    return NULL;
+  o2 = gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), p);
+  if (o2 < 0.)
+    return NULL;
+  o3 = gts_point_orientation (GTS_POINT (v3), GTS_POINT (v1), p);
+  if (o3 < 0.)
+    return NULL;  
+  if (orientation) *orientation = inverted ? -o : o;
+  if (o1 == 0.) {
+    if (o2 == 0.)
+      return GTS_OBJECT (v2);
+    if (o3 == 0.)
+      return GTS_OBJECT (v1);
+    return GTS_OBJECT (e1);
+  }
+  if (o2 == 0.) {
+    if (o3 == 0.)
+      return GTS_OBJECT (v3);
+    return GTS_OBJECT (e2);
+  }
+  if (o3 == 0.)
+    return GTS_OBJECT (e3);
+  return GTS_OBJECT (t);
+}
+
+/**
+ * gts_triangle_interpolate_height:
+ * @t: a #GtsTriangle.
+ * @p: a #GtsPoint.
+ *
+ * Fills the z-coordinate of point @p belonging to the plane
+ * projection of triangle @t with the linearly interpolated value of
+ * the z-coordinates of the vertices of @t.
+ */
+void gts_triangle_interpolate_height (GtsTriangle * t, GtsPoint * p)
+{
+  GtsPoint * p1, * p2, * p3;
+  gdouble x1, x2, y1, y2, det;
+
+  g_return_if_fail (t != NULL);
+  g_return_if_fail (p != NULL);
+
+  p1 = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
+  p2 = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
+  p3 = GTS_POINT (gts_triangle_vertex (t));
+
+  x1 = p2->x - p1->x;
+  y1 = p2->y - p1->y;
+  x2 = p3->x - p1->x;
+  y2 = p3->y - p1->y;
+  det = x1*y2 - x2*y1;
+  if (det == 0.)
+    p->z = (p1->z + p2->z + p3->z)/3.;
+  else {
+    gdouble x = p->x - p1->x;
+    gdouble y = p->y - p1->y;
+    gdouble a = (x*y2 - y*x2)/det;
+    gdouble b = (y*x1 - x*y1)/det;
+
+    p->z = (1. - a - b)*p1->z + a*p2->z + b*p3->z;
+  }
+}
diff --git a/gts/tribox3.c b/gts/tribox3.c
new file mode 100644
index 0000000..c0ea778
--- /dev/null
+++ b/gts/tribox3.c
@@ -0,0 +1,192 @@
+/**
+ * History:
+ * 2004-10-27 Stephane Popinet: changed float to double
+ */
+
+/********************************************************/
+/* AABB-triangle overlap test code                      */
+/* by Tomas Akenine-Möller                              */
+/* Function: int triBoxOverlap(float boxcenter[3],      */
+/*          float boxhalfsize[3],float triverts[3][3]); */
+/* History:                                             */
+/*   2001-03-05: released the code in its first version */
+/*   2001-06-18: changed the order of the tests, faster */
+/*                                                      */
+/* Acknowledgement: Many thanks to Pierre Terdiman for  */
+/* suggestions and discussions on how to optimize code. */
+/* Thanks to David Hunt for finding a ">="-bug!         */
+/********************************************************/
+#include <math.h>
+#include <stdio.h>
+
+#define X 0
+#define Y 1
+#define Z 2
+
+#define CROSS(dest,v1,v2) \
+          dest[0]=v1[1]*v2[2]-v1[2]*v2[1]; \
+          dest[1]=v1[2]*v2[0]-v1[0]*v2[2]; \
+          dest[2]=v1[0]*v2[1]-v1[1]*v2[0]; 
+
+#define DOT(v1,v2) (v1[0]*v2[0]+v1[1]*v2[1]+v1[2]*v2[2])
+
+#define SUB(dest,v1,v2) \
+          dest[0]=v1[0]-v2[0]; \
+          dest[1]=v1[1]-v2[1]; \
+          dest[2]=v1[2]-v2[2]; 
+
+#define FINDMINMAX(x0,x1,x2,min,max) \
+  min = max = x0;   \
+  if(x1<min) min=x1;\
+  if(x1>max) max=x1;\
+  if(x2<min) min=x2;\
+  if(x2>max) max=x2;
+
+int planeBoxOverlap(double normal[3], double vert[3], double maxbox[3])	// -NJMP-
+{
+  int q;
+  double vmin[3],vmax[3],v;
+  for(q=X;q<=Z;q++)
+  {
+    v=vert[q];					// -NJMP-
+    if(normal[q]>0.0f)
+    {
+      vmin[q]=-maxbox[q] - v;	// -NJMP-
+      vmax[q]= maxbox[q] - v;	// -NJMP-
+    }
+    else
+    {
+      vmin[q]= maxbox[q] - v;	// -NJMP-
+      vmax[q]=-maxbox[q] - v;	// -NJMP-
+    }
+  }
+  if(DOT(normal,vmin)>0.0f) return 0;	// -NJMP-
+  if(DOT(normal,vmax)>=0.0f) return 1;	// -NJMP-
+  
+  return 0;
+}
+
+
+/*======================== X-tests ========================*/
+#define AXISTEST_X01(a, b, fa, fb)			   \
+	p0 = a*v0[Y] - b*v0[Z];			       	   \
+	p2 = a*v2[Y] - b*v2[Z];			       	   \
+        if(p0<p2) {min=p0; max=p2;} else {min=p2; max=p0;} \
+	rad = fa * boxhalfsize[Y] + fb * boxhalfsize[Z];   \
+	if(min>rad || max<-rad) return 0;
+
+#define AXISTEST_X2(a, b, fa, fb)			   \
+	p0 = a*v0[Y] - b*v0[Z];			           \
+	p1 = a*v1[Y] - b*v1[Z];			       	   \
+        if(p0<p1) {min=p0; max=p1;} else {min=p1; max=p0;} \
+	rad = fa * boxhalfsize[Y] + fb * boxhalfsize[Z];   \
+	if(min>rad || max<-rad) return 0;
+
+/*======================== Y-tests ========================*/
+#define AXISTEST_Y02(a, b, fa, fb)			   \
+	p0 = -a*v0[X] + b*v0[Z];		      	   \
+	p2 = -a*v2[X] + b*v2[Z];	       	       	   \
+        if(p0<p2) {min=p0; max=p2;} else {min=p2; max=p0;} \
+	rad = fa * boxhalfsize[X] + fb * boxhalfsize[Z];   \
+	if(min>rad || max<-rad) return 0;
+
+#define AXISTEST_Y1(a, b, fa, fb)			   \
+	p0 = -a*v0[X] + b*v0[Z];		      	   \
+	p1 = -a*v1[X] + b*v1[Z];	     	       	   \
+        if(p0<p1) {min=p0; max=p1;} else {min=p1; max=p0;} \
+	rad = fa * boxhalfsize[X] + fb * boxhalfsize[Z];   \
+	if(min>rad || max<-rad) return 0;
+
+/*======================== Z-tests ========================*/
+
+#define AXISTEST_Z12(a, b, fa, fb)			   \
+	p1 = a*v1[X] - b*v1[Y];			           \
+	p2 = a*v2[X] - b*v2[Y];			       	   \
+        if(p2<p1) {min=p2; max=p1;} else {min=p1; max=p2;} \
+	rad = fa * boxhalfsize[X] + fb * boxhalfsize[Y];   \
+	if(min>rad || max<-rad) return 0;
+
+#define AXISTEST_Z0(a, b, fa, fb)			   \
+	p0 = a*v0[X] - b*v0[Y];				   \
+	p1 = a*v1[X] - b*v1[Y];			           \
+        if(p0<p1) {min=p0; max=p1;} else {min=p1; max=p0;} \
+	rad = fa * boxhalfsize[X] + fb * boxhalfsize[Y];   \
+	if(min>rad || max<-rad) return 0;
+
+int triBoxOverlap(double boxcenter[3],double boxhalfsize[3],double triverts[3][3])
+{
+
+  /*    use separating axis theorem to test overlap between triangle and box */
+  /*    need to test for overlap in these directions: */
+  /*    1) the {x,y,z}-directions (actually, since we use the AABB of the triangle */
+  /*       we do not even need to test these) */
+  /*    2) normal of the triangle */
+  /*    3) crossproduct(edge from tri, {x,y,z}-directin) */
+  /*       this gives 3x3=9 more tests */
+   double v0[3],v1[3],v2[3];
+//   double axis[3];
+   double min,max,p0,p1,p2,rad,fex,fey,fez;		// -NJMP- "d" local variable removed
+   double normal[3],e0[3],e1[3],e2[3];
+
+   /* This is the fastest branch on Sun */
+   /* move everything so that the boxcenter is in (0,0,0) */
+   SUB(v0,triverts[0],boxcenter);
+   SUB(v1,triverts[1],boxcenter);
+   SUB(v2,triverts[2],boxcenter);
+
+   /* compute triangle edges */
+   SUB(e0,v1,v0);      /* tri edge 0 */
+   SUB(e1,v2,v1);      /* tri edge 1 */
+   SUB(e2,v0,v2);      /* tri edge 2 */
+
+   /* Bullet 3:  */
+   /*  test the 9 tests first (this was faster) */
+   fex = fabsf(e0[X]);
+   fey = fabsf(e0[Y]);
+   fez = fabsf(e0[Z]);
+   AXISTEST_X01(e0[Z], e0[Y], fez, fey);
+   AXISTEST_Y02(e0[Z], e0[X], fez, fex);
+   AXISTEST_Z12(e0[Y], e0[X], fey, fex);
+
+   fex = fabsf(e1[X]);
+   fey = fabsf(e1[Y]);
+   fez = fabsf(e1[Z]);
+   AXISTEST_X01(e1[Z], e1[Y], fez, fey);
+   AXISTEST_Y02(e1[Z], e1[X], fez, fex);
+   AXISTEST_Z0(e1[Y], e1[X], fey, fex);
+
+   fex = fabsf(e2[X]);
+   fey = fabsf(e2[Y]);
+   fez = fabsf(e2[Z]);
+   AXISTEST_X2(e2[Z], e2[Y], fez, fey);
+   AXISTEST_Y1(e2[Z], e2[X], fez, fex);
+   AXISTEST_Z12(e2[Y], e2[X], fey, fex);
+
+   /* Bullet 1: */
+   /*  first test overlap in the {x,y,z}-directions */
+   /*  find min, max of the triangle each direction, and test for overlap in */
+   /*  that direction -- this is equivalent to testing a minimal AABB around */
+   /*  the triangle against the AABB */
+
+   /* test in X-direction */
+   FINDMINMAX(v0[X],v1[X],v2[X],min,max);
+   if(min>boxhalfsize[X] || max<-boxhalfsize[X]) return 0;
+
+   /* test in Y-direction */
+   FINDMINMAX(v0[Y],v1[Y],v2[Y],min,max);
+   if(min>boxhalfsize[Y] || max<-boxhalfsize[Y]) return 0;
+
+   /* test in Z-direction */
+   FINDMINMAX(v0[Z],v1[Z],v2[Z],min,max);
+   if(min>boxhalfsize[Z] || max<-boxhalfsize[Z]) return 0;
+
+   /* Bullet 2: */
+   /*  test if the box intersects the plane of the triangle */
+   /*  compute plane equation of triangle: normal*x+d=0 */
+   CROSS(normal,e0,e1);
+   // -NJMP- (line removed here)
+   if(!planeBoxOverlap(normal,v0,boxhalfsize)) return 0;	// -NJMP-
+
+   return 1;   /* box and triangle overlaps */
+}
+
diff --git a/gts/vertex.c b/gts/vertex.c
new file mode 100644
index 0000000..d312869
--- /dev/null
+++ b/gts/vertex.c
@@ -0,0 +1,780 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <math.h>
+#include "gts.h"
+
+gboolean gts_allow_floating_vertices = FALSE;
+
+static void vertex_destroy (GtsObject * object)
+{
+  GtsVertex * vertex = GTS_VERTEX (object);
+  GSList * i;
+
+  i = vertex->segments;
+  while (i) {
+    GTS_OBJECT_SET_FLAGS (i->data, GTS_DESTROYED);
+    i = i->next;
+  }
+  i = vertex->segments;
+  while (i) {
+    GSList * next = i->next;
+    gts_object_destroy (i->data);
+    i = next;
+  }
+  g_assert (vertex->segments == NULL);
+
+  (* GTS_OBJECT_CLASS (gts_vertex_class ())->parent_class->destroy) (object);
+}
+
+static void vertex_clone (GtsObject * clone, GtsObject * object)
+{
+  (* GTS_OBJECT_CLASS (gts_vertex_class ())->parent_class->clone) (clone, 
+								   object);
+  GTS_VERTEX (clone)->segments = NULL;
+}
+
+static void vertex_class_init (GtsVertexClass * klass)
+{
+  klass->intersection_attributes = NULL;
+  GTS_OBJECT_CLASS (klass)->clone = vertex_clone;
+  GTS_OBJECT_CLASS (klass)->destroy = vertex_destroy;
+}
+
+static void vertex_init (GtsVertex * vertex)
+{
+  vertex->segments = NULL;
+}
+
+/**
+ * gts_vertex_class:
+ *
+ * Returns: the #GtsVertexClass.
+ */
+GtsVertexClass * gts_vertex_class (void)
+{
+  static GtsVertexClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo vertex_info = {
+      "GtsVertex",
+      sizeof (GtsVertex),
+      sizeof (GtsVertexClass),
+      (GtsObjectClassInitFunc) vertex_class_init,
+      (GtsObjectInitFunc) vertex_init,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_point_class ()), 
+				  &vertex_info);
+  }
+
+  return klass;
+}
+
+/**
+ * gts_vertex_new:
+ * @klass: a #GtsVertexClass.
+ * @x: the x-coordinate of the vertex to create.
+ * @y: the y-coordinate of the vertex to create.
+ * @z: the y-coordinate of the vertex to create.
+ *
+ * Returns: a new #GtsVertex with @x, @y and @z as coordinates.
+ */
+GtsVertex * gts_vertex_new (GtsVertexClass * klass,
+			    gdouble x, gdouble y, gdouble z)
+{
+  GtsVertex * v;
+
+  v = GTS_VERTEX (gts_object_new (GTS_OBJECT_CLASS (klass)));
+  gts_point_set (GTS_POINT (v), x, y, z);
+
+  return v;
+}
+
+/**
+ * gts_vertex_replace:
+ * @v: a #GtsVertex.
+ * @with: another #GtsVertex.
+ *
+ * Replaces vertex @v with vertex @with. @v and @with must be
+ * different.  All the #GtsSegment which have @v has one of their
+ * vertices are updated.  The segments list of vertex @v is freed and
+ * @v->segments is set to %NULL.  
+ */
+void gts_vertex_replace (GtsVertex * v, GtsVertex * with)
+{
+  GSList * i;
+
+  g_return_if_fail (v != NULL);
+  g_return_if_fail (with != NULL);
+  g_return_if_fail (v != with);
+
+  i = v->segments;
+  while (i) {
+    GtsSegment * s = i->data;
+    if (s->v1 != with && s->v2 != with)
+      with->segments = g_slist_prepend (with->segments, s);
+    if (s->v1 == v) s->v1 = with;
+    if (s->v2 == v) s->v2 = with;
+    i = i->next;
+  }
+  g_slist_free (v->segments);
+  v->segments = NULL;
+}
+
+/**
+ * gts_vertex_is_unattached:
+ * @v: a #GtsVertex.
+ *
+ * Returns: %TRUE if @v is not the endpoint of any #GtsSegment, 
+ * %FALSE otherwise.
+ */
+gboolean gts_vertex_is_unattached (GtsVertex * v)
+{
+  g_return_val_if_fail (v != NULL, FALSE);
+  if (v->segments == NULL)
+    return TRUE;
+  return FALSE;
+}
+
+/**
+ * gts_vertices_are_connected:
+ * @v1: a #GtsVertex.
+ * @v2: another #GtsVertex.
+ *
+ * Returns: if @v1 and @v2 are the vertices of the same #GtsSegment
+ * this segment else %NULL.
+ */
+GtsSegment * gts_vertices_are_connected (GtsVertex * v1, GtsVertex * v2)
+{
+  GSList * i;
+  
+  g_return_val_if_fail (v1 != NULL, FALSE);
+  g_return_val_if_fail (v2 != NULL, FALSE);
+  
+  i = v1->segments;
+  while (i) {
+    GtsSegment * s = i->data;
+
+    if (s->v1 == v2 || s->v2 == v2)
+      return s;
+    i = i->next;
+  }
+  return NULL;
+}
+
+/**
+ * gts_vertices_from_segments:
+ * @segments: a list of #GtsSegment.
+ *
+ * Returns: a list of #GtsVertex, vertices of a #GtsSegment in @segments.
+ * Each element in the list is unique (no duplicates).
+ */
+GSList * gts_vertices_from_segments (GSList * segments)
+{
+  GHashTable * hash;
+  GSList * vertices = NULL, * i;
+  
+  hash = g_hash_table_new (NULL, NULL);
+  i = segments;
+  while (i) {
+    GtsSegment * s = i->data;
+    if (g_hash_table_lookup (hash, s->v1) == NULL) {
+      vertices = g_slist_prepend (vertices, s->v1);
+      g_hash_table_insert (hash, s->v1, s);
+    }
+    if (g_hash_table_lookup (hash, s->v2) == NULL) {
+      vertices = g_slist_prepend (vertices, s->v2);
+      g_hash_table_insert (hash, s->v2, s);
+    }
+    i = i->next;
+  }
+  g_hash_table_destroy (hash);
+  return vertices;
+}
+
+/**
+ * gts_vertex_triangles:
+ * @v: a #GtsVertex.
+ * @list: a list of #GtsTriangle.
+ *
+ * Adds all the #GtsTriangle which share @v as a vertex and do not
+ * already belong to @list.
+ *
+ * Returns: the new list of unique #GtsTriangle which share @v as a
+ * vertex.  
+ */
+GSList * gts_vertex_triangles (GtsVertex * v, 
+			       GSList * list)
+{
+  GSList * i;
+
+  g_return_val_if_fail (v != NULL, NULL);
+
+  i = v->segments;
+  while (i) {
+    GtsSegment * s = i->data;
+    if (GTS_IS_EDGE (s)) {
+      GSList * j = GTS_EDGE (s)->triangles;
+      while (j) {
+	if (!g_slist_find (list, j->data))
+	  list = g_slist_prepend (list, j->data);
+	j = j->next;
+      }
+    }
+    i = i->next;
+  }
+  return list;
+}
+
+/**
+ * gts_vertex_faces:
+ * @v: a #GtsVertex.
+ * @surface: a #GtsSurface or %NULL.
+ * @list: a list of #GtsFace.
+ *
+ * Adds all the #GtsFace belonging to @surface (if not %NULL) which share 
+ * @v as a vertex and do not already belong to @list.
+ *
+ * Returns: the new list of unique #GtsFace belonging to @surface 
+ * which share @v as a vertex.
+ */
+GSList * gts_vertex_faces (GtsVertex * v, 
+			   GtsSurface * surface, 
+			   GSList * list)
+{
+  GSList * i;
+
+  g_return_val_if_fail (v != NULL, NULL);
+
+  i = v->segments;
+  while (i) {
+    GtsSegment * s = i->data;
+    if (GTS_IS_EDGE (s)) {
+      GSList * j = GTS_EDGE (s)->triangles;
+      while (j) {
+	GtsTriangle * t = j->data;
+	if (GTS_IS_FACE (t) 
+	    && 
+	    (!surface || gts_face_has_parent_surface (GTS_FACE (t), surface)) 
+	    &&
+	    !g_slist_find (list, t))
+	  list = g_slist_prepend (list, t);
+	j = j->next;
+      }
+    }
+    i = i->next;
+  }
+  return list;
+}
+
+/**
+ * gts_vertex_neighbors:
+ * @v: a #GtsVertex.
+ * @list: a list of #GtsVertex.
+ * @surface: a #GtsSurface or %NULL.
+ *
+ * Adds to @list all the #GtsVertex connected to @v by a #GtsSegment and not
+ * already in @list. If @surface is not %NULL only the vertices connected to
+ * @v by an edge belonging to @surface are considered.
+ *
+ * Returns: the new list of unique #GtsVertex.
+ */
+GSList * gts_vertex_neighbors (GtsVertex * v, 
+			       GSList * list,
+			       GtsSurface * surface)
+{
+  GSList * i;
+
+  g_return_val_if_fail (v != NULL, NULL);
+
+  i = v->segments;
+  while (i) {
+    GtsSegment * s = i->data;
+    GtsVertex * v1 = s->v1 == v ? s->v2 : s->v1;
+    if (v1 != v && 
+	(!surface || 
+	 (GTS_IS_EDGE (s) && 
+	  gts_edge_has_parent_surface (GTS_EDGE (s), surface))) &&
+	!g_slist_find (list, v1))
+      list = g_slist_prepend (list, v1);
+    i = i->next;
+  }
+  return list;
+}
+
+/**
+ * gts_vertex_is_boundary:
+ * @v: a #GtsVertex.
+ * @surface: a #GtsSurface or %NULL.
+ * 
+ * Returns: %TRUE if @v is used by a #GtsEdge boundary of @surface as
+ * determined by gts_edge_is_boundary(), %FALSE otherwise.
+ */
+gboolean gts_vertex_is_boundary (GtsVertex * v, GtsSurface * surface)
+{
+  GSList * i;
+
+  g_return_val_if_fail (v != NULL, FALSE);
+  
+  i = v->segments;
+  while (i) {
+    if (GTS_IS_EDGE (i->data) && 
+	gts_edge_is_boundary (i->data, surface))
+      return TRUE;
+    i = i->next;
+  }
+
+  return FALSE;
+}
+
+/**
+ * gts_vertices_merge:
+ * @vertices: a list of #GtsVertex.
+ * @epsilon: half the size of the bounding box to consider for each vertex.
+ * @check: function called for each pair of vertices about to be merged
+ * or %NULL.
+ *
+ * For each vertex v in @vertices look if there are any vertex of
+ * @vertices contained in a box centered on v of size 2*@epsilon. If
+ * there are and if @check is not %NULL and returns %TRUE, replace
+ * them with v (using gts_vertex_replace()), destroy them and remove
+ * them from list.  This is done efficiently using Kd-Trees.
+ *
+ * Returns: the updated list of vertices.  
+ */
+GList * gts_vertices_merge (GList * vertices, 
+			    gdouble epsilon,
+			    gboolean (* check) (GtsVertex *, GtsVertex *))
+{
+  GPtrArray * array;
+  GList * i;
+  GNode * kdtree;
+
+  g_return_val_if_fail (vertices != NULL, 0);
+
+  array = g_ptr_array_new ();
+  i = vertices;
+  while (i) {
+    g_ptr_array_add (array, i->data);
+    i = i->next;
+  }
+  kdtree = gts_kdtree_new (array, NULL);
+  g_ptr_array_free (array, TRUE);
+  
+  i = vertices;
+  while (i) {
+    GtsVertex * v = i->data;
+    if (!GTS_OBJECT (v)->reserved) { /* Do something only if v is active */
+      GtsBBox * bbox;
+      GSList * selected, * j;
+
+      /* build bounding box */
+      bbox = gts_bbox_new (gts_bbox_class (),
+			   v, 
+			   GTS_POINT (v)->x - epsilon,
+			   GTS_POINT (v)->y - epsilon,
+			   GTS_POINT (v)->z - epsilon,
+			   GTS_POINT (v)->x + epsilon,
+			   GTS_POINT (v)->y + epsilon,
+			   GTS_POINT (v)->z + epsilon);
+
+      /* select vertices which are inside bbox using kdtree */
+      j = selected = gts_kdtree_range (kdtree, bbox, NULL);
+      while (j) {
+	GtsVertex * sv = j->data;
+	if (sv != v && !GTS_OBJECT (sv)->reserved && (!check || (*check) (sv, v))) {
+	  /* sv is not v and is active */
+	  gts_vertex_replace (sv, v);
+	  GTS_OBJECT (sv)->reserved = sv; /* mark sv as inactive */
+	}
+	j = j->next;
+      }
+      g_slist_free (selected);
+      gts_object_destroy (GTS_OBJECT (bbox));
+    }
+    i = i->next;
+  }
+
+  gts_kdtree_destroy (kdtree);
+
+  /* destroy inactive vertices and removes them from list */
+
+  /* we want to control vertex destruction */
+  gts_allow_floating_vertices = TRUE;
+
+  i = vertices;
+  while (i) {
+    GtsVertex * v = i->data;
+    GList * next = i->next;
+    if (GTS_OBJECT (v)->reserved) { /* v is inactive */
+      gts_object_destroy (GTS_OBJECT (v));
+      vertices = g_list_remove_link (vertices, i);
+      g_list_free_1 (i);
+    }
+    i = next;
+  }
+  gts_allow_floating_vertices = FALSE; 
+
+  return vertices;
+}
+
+/* returns the list of edges belonging to @surface turning around @v */
+static GSList * edge_fan_list (GtsVertex * v,
+			       GtsSurface * surface,
+			       GtsFace * f, 
+			       GtsEdge * e,
+			       GtsFace * first)
+{
+  GSList * i = e->triangles;
+  GtsFace * neighbor = NULL;
+  GtsEdge * next = NULL, * enext = NULL;
+
+  while (i) {
+    GtsFace * f1 = i->data;
+    if (GTS_IS_FACE (f1) &&
+	f1 != f &&
+	gts_face_has_parent_surface (f1, surface)) {
+      g_return_val_if_fail (neighbor == NULL, NULL); /* non-manifold edge */
+      neighbor = f1;
+    }
+    i = i->next;
+  }
+  if (neighbor == NULL || neighbor == first) /* end of fan */
+    return NULL;
+
+  if (GTS_TRIANGLE (neighbor)->e1 == e) {
+    next = GTS_TRIANGLE (neighbor)->e2;
+    enext = GTS_TRIANGLE (neighbor)->e3;
+  }
+  else if (GTS_TRIANGLE (neighbor)->e2 == e) {
+    next = GTS_TRIANGLE (neighbor)->e3;
+    enext = GTS_TRIANGLE (neighbor)->e1;
+  }
+  else if (GTS_TRIANGLE (neighbor)->e3 == e) {
+    next = GTS_TRIANGLE (neighbor)->e1;
+    enext = GTS_TRIANGLE (neighbor)->e2;
+  }
+  else
+    g_assert_not_reached ();
+
+  /* checking for correct orientation */
+  g_return_val_if_fail (GTS_SEGMENT (enext)->v1 == v ||
+			GTS_SEGMENT (enext)->v2 == v, NULL);
+
+  return g_slist_prepend (edge_fan_list (v, surface, neighbor, enext, first), 
+			  next);
+}
+
+/**
+ * gts_vertex_fan_oriented:
+ * @v: a #GtsVertex.
+ * @surface: a #GtsSurface.
+ *
+ * Returns: a list of #GtsEdge describing in counterclockwise order the 
+ * boundary of the fan of summit @v, the faces of the fan belonging to 
+ * @surface.
+ */
+GSList * gts_vertex_fan_oriented (GtsVertex * v, GtsSurface * surface)
+{
+  GtsFace * f = NULL;
+  guint d = 2;
+  GSList * i;
+  GtsVertex * v1, * v2, * v3;
+  GtsEdge * e1, * e2, * e3;
+
+  g_return_val_if_fail (v != NULL, NULL);
+  g_return_val_if_fail (surface != NULL, NULL);
+
+  i = v->segments;
+  while (i) {
+    GtsEdge * e = i->data;
+    if (GTS_IS_EDGE (e)) {
+      GSList * j = e->triangles;
+      GtsFace * f1 = NULL;
+      guint degree = 0;
+      while (j) {
+	if (GTS_IS_FACE (j->data) &&
+	    gts_face_has_parent_surface (j->data, surface)) {
+	  f1 = j->data;
+	  degree++;
+	}
+	j = j->next;
+      }
+      if (f1 != NULL) {
+	g_return_val_if_fail (degree <= 2, NULL); /* non-manifold edge */
+	if (degree == 1) {
+	  gts_triangle_vertices_edges (GTS_TRIANGLE (f1), NULL,
+				       &v1, &v2, &v3, &e1, &e2, &e3);
+	  if (v == v2) {
+	    e2 = e3;
+	    e3 = e1;
+	  }
+	  else if (v == v3) {
+	    e3 = e2;
+	    e2 = e1;
+	  }
+	  if (e3 != e) {
+	    d = 1;
+	    f = f1;
+	  }
+	}
+	else if (degree <= d)
+	  f = f1;
+      }
+    }
+    i = i->next;
+  }
+
+  if (f == NULL)
+    return NULL;
+
+  gts_triangle_vertices_edges (GTS_TRIANGLE (f), NULL,
+			       &v1, &v2, &v3, &e1, &e2, &e3);
+  if (v == v2) {
+    e2 = e3;
+    e3 = e1;
+  }
+  else if (v == v3) {
+    e3 = e2;
+    e2 = e1;
+  }
+
+  return g_slist_prepend (edge_fan_list (v, surface, f, e3, f), e2);
+}
+
+#define edge_use_vertex(e, v) (GTS_SEGMENT(e)->v1 == v ||\
+			       GTS_SEGMENT(e)->v2 == v)
+
+static GtsEdge * replace_vertex (GtsTriangle * t, 
+				 GtsEdge * e1,
+				 GtsVertex * v, 
+				 GtsVertex * with)
+{
+  GtsEdge * e = NULL;
+
+  if (t->e1 != e1 && edge_use_vertex (t->e1, v))
+    e = t->e1;
+  else if (t->e2 != e1 && edge_use_vertex (t->e2, v))
+    e = t->e2;
+  else if (t->e3 != e1 && edge_use_vertex (t->e3, v))
+    e = t->e3;
+  else
+    return NULL;
+
+  if (with != v) {
+    GtsSegment * s = GTS_SEGMENT (e);
+    if (s->v1 == v) s->v1 = with;
+    if (s->v2 == v) s->v2 = with;
+    with->segments = g_slist_prepend (with->segments, s);
+    v->segments = g_slist_remove (v->segments, s);
+  }
+
+  return e;
+}
+
+static void triangle_next (GtsEdge * e, GtsVertex * v, GtsVertex * with)
+{
+  GSList * i;
+
+  if (e == NULL)
+    return;
+    
+  i = e->triangles;
+  while (i) {
+    GtsTriangle * t = i->data;
+    if (GTS_OBJECT (t)->reserved) {
+      GTS_OBJECT (t)->reserved = NULL;
+      triangle_next (replace_vertex (t, e, v, with), v, with);
+    }
+    i = i->next;
+  }
+}
+
+/** 
+ * gts_vertex_is_contact: 
+ * @v: a #GtsVertex.  
+ * @sever: if %TRUE and if @v is a contact vertex between two or more
+ * sets of connected triangles replaces it with as many vertices,
+ * clones of @v.
+ *
+ * Returns: the number of sets of connected triangles sharing @v as a
+ * contact vertex.  
+ */
+guint gts_vertex_is_contact (GtsVertex * v, gboolean sever)
+{
+  GSList * triangles, * i;
+  GtsVertex * with = v;
+  guint ncomponent = 0;
+
+  g_return_val_if_fail (v != NULL, 0);
+
+  triangles = gts_vertex_triangles (v, NULL);
+  i = triangles;
+  while (i) {
+    GTS_OBJECT (i->data)->reserved = i;
+    i = i->next;
+  }
+
+  i = triangles;
+  while (i) {
+    GtsTriangle * t = i->data;
+    if (GTS_OBJECT (t)->reserved) {
+      GtsEdge * e;
+      if (ncomponent && sever)
+	with = GTS_VERTEX (gts_object_clone (GTS_OBJECT (v)));
+      GTS_OBJECT (t)->reserved = NULL;
+      e = replace_vertex (t, NULL, v, with);
+      triangle_next (e, v, with);
+      triangle_next (replace_vertex (t, e, v, with), v, with);
+      ncomponent++;
+    }
+    i = i->next;
+  }
+  g_slist_free (triangles);
+
+  return ncomponent;
+}
+
+/* GtsVertexNormal: Object */
+
+static void vertex_normal_attributes (GtsVertex * v,
+				      GtsObject * e,
+				      GtsObject * t)
+{
+  g_return_if_fail (GTS_IS_EDGE (e));
+  g_return_if_fail (GTS_IS_TRIANGLE (t));
+
+  if (GTS_IS_VERTEX_NORMAL (GTS_SEGMENT (e)->v1) &&
+      GTS_IS_VERTEX_NORMAL (GTS_SEGMENT (e)->v2)) {
+    GtsPoint * p1 = GTS_POINT (GTS_SEGMENT (e)->v1);
+    GtsPoint * p2 = GTS_POINT (GTS_SEGMENT (e)->v2);
+    GtsPoint * p = GTS_POINT (v);
+    gdouble a, b, lambda;
+    guint i;
+
+    a = p2->x - p1->x; b = p->x - p1->x;
+    if (fabs (p2->y - p1->y) > fabs (a)) {
+      a = p2->y - p1->y; b = p->y - p1->y;      
+    }
+    if (fabs (p2->z - p1->z) > fabs (a)) {
+      a = p2->z - p1->z; b = p->z - p1->z;      
+    }
+    lambda = a != 0. ? b/a : 0.;
+    for (i = 0; i < 3; i++)
+      GTS_VERTEX_NORMAL (v)->n[i] = 
+	(1. - lambda)*GTS_VERTEX_NORMAL (GTS_SEGMENT (e)->v1)->n[i] +
+	lambda*GTS_VERTEX_NORMAL (GTS_SEGMENT (e)->v2)->n[i];
+  }
+  else {
+    GtsVertex * v1, * v2, * v3;
+
+    gts_triangle_vertices (GTS_TRIANGLE (t), &v1, &v2, &v3);
+    if (GTS_IS_VERTEX_NORMAL (v1) && 
+	GTS_IS_VERTEX_NORMAL (v2) &&
+	GTS_IS_VERTEX_NORMAL (v3)) {
+      GtsVector a1, a2, a3, det;
+      guint i, j = 0;
+      gdouble l1, l2;
+
+      gts_vector_init (a1, GTS_POINT (v1), GTS_POINT (v));
+      gts_vector_init (a2, GTS_POINT (v1), GTS_POINT (v2));
+      gts_vector_init (a3, GTS_POINT (v1), GTS_POINT (v3));
+      gts_vector_cross (det, a2, a3);
+      if (fabs (det[1]) > fabs (det[0])) j = 1;
+      if (fabs (det[2]) > fabs (det[j])) j = 2;
+      if (det[j] == 0.) {
+	g_warning ("vertex_normal_attributes: det[%d] == 0.", j);
+	return;
+      }
+      switch (j) {
+      case 0: 
+	l1 = (a1[1]*a3[2] - a1[2]*a3[1])/det[0]; 
+	l2 = (a1[2]*a2[1] - a1[1]*a2[2])/det[0]; 
+	break;
+      case 1:
+	l1 = (a1[2]*a3[0] - a1[0]*a3[2])/det[1];
+	l2 = (a1[0]*a2[2] - a1[2]*a2[0])/det[1];
+	break;
+      case 2:
+	l1 = (a1[0]*a3[1] - a1[1]*a3[0])/det[2];
+	l2 = (a1[1]*a2[0] - a1[0]*a2[1])/det[2];
+	break;
+      default:
+	l1 = l2 = 0.;
+      }
+      for (i = 0; i < 3; i++)
+	GTS_VERTEX_NORMAL (v)->n[i] = 
+	  GTS_VERTEX_NORMAL (v1)->n[i]*(1. - l1 - l2) +
+	  GTS_VERTEX_NORMAL (v2)->n[i]*l1 +
+	  GTS_VERTEX_NORMAL (v3)->n[i]*l2;
+    }
+  }
+}
+
+static void gts_vertex_normal_class_init (GtsVertexClass * klass)
+{
+  klass->intersection_attributes = vertex_normal_attributes;
+}
+
+GtsVertexClass * gts_vertex_normal_class (void)
+{
+  static GtsVertexClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo gts_vertex_normal_info = {
+      "GtsVertexNormal",
+      sizeof (GtsVertexNormal),
+      sizeof (GtsVertexClass),
+      (GtsObjectClassInitFunc) gts_vertex_normal_class_init,
+      (GtsObjectInitFunc) NULL,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_vertex_class ()),
+				  &gts_vertex_normal_info);
+  }
+
+  return klass;
+}
+
+/* GtsColorVertex: Object */
+
+GtsVertexClass * gts_color_vertex_class (void)
+{
+  static GtsVertexClass * klass = NULL;
+
+  if (klass == NULL) {
+    GtsObjectClassInfo gts_color_vertex_info = {
+      "GtsColorVertex",
+      sizeof (GtsColorVertex),
+      sizeof (GtsVertexClass),
+      (GtsObjectClassInitFunc) NULL,
+      (GtsObjectInitFunc) NULL,
+      (GtsArgSetFunc) NULL,
+      (GtsArgGetFunc) NULL
+    };
+    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_vertex_class ()),
+				  &gts_color_vertex_info);
+  }
+
+  return klass;
+}
+
diff --git a/gts/vopt.c b/gts/vopt.c
new file mode 100644
index 0000000..d772af9
--- /dev/null
+++ b/gts/vopt.c
@@ -0,0 +1,521 @@
+/* GTS - Library for the manipulation of triangulated surfaces
+ * Copyright (C) 1999 Stéphane Popinet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "gts.h"
+
+/* #define DEBUG_VOPT */
+
+/* compute the normal (nx, ny, nz) as the cross-product of the first two 
+   oriented edges and the norm nt = |t| as (v1xv2).v3 */
+static void triangle_normal (GtsTriangle * t, 
+			     gdouble * nx, 
+			     gdouble * ny, 
+			     gdouble * nz,
+			     gdouble * nt)
+{
+  GtsPoint * p1, * p2 = NULL, * p3 = NULL;
+  gdouble x1, y1, z1, x2, y2, z2;
+
+  g_return_if_fail (t != NULL);
+
+  p1 = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
+  if (GTS_SEGMENT (t->e1)->v1 == GTS_SEGMENT (t->e2)->v1) {
+    p2 = GTS_POINT (GTS_SEGMENT (t->e2)->v2);
+    p3 = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
+  }
+  else if (GTS_SEGMENT (t->e1)->v2 == GTS_SEGMENT (t->e2)->v2) {
+    p2 = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
+    p3 = GTS_POINT (GTS_SEGMENT (t->e2)->v1);
+  }
+  else if (GTS_SEGMENT (t->e1)->v1 == GTS_SEGMENT (t->e2)->v2) {
+    p2 = GTS_POINT (GTS_SEGMENT (t->e2)->v1);
+    p3 = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
+  }
+  else if (GTS_SEGMENT (t->e1)->v2 == GTS_SEGMENT (t->e2)->v1) {
+    p2 = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
+    p3 = GTS_POINT (GTS_SEGMENT (t->e2)->v2);
+  }
+  else
+    g_assert_not_reached ();
+
+  x1 = p2->x - p1->x;
+  y1 = p2->y - p1->y;
+  z1 = p2->z - p1->z;
+
+  x2 = p3->x - p1->x;
+  y2 = p3->y - p1->y;
+  z2 = p3->z - p1->z;
+
+  *nt = ((p1->y*p2->z - p1->z*p2->y)*p3->x + 
+	 (p1->z*p2->x - p1->x*p2->z)*p3->y + 
+	 (p1->x*p2->y - p1->y*p2->x)*p3->z);
+  *nx = y1*z2 - z1*y2;
+  *ny = z1*x2 - x1*z2;
+  *nz = x1*y2 - y1*x2;
+}
+
+static void boundary_preservation (GtsEdge * edge,
+				   GtsFace * f,
+				   GtsVector e1, GtsVector e2,
+				   GtsMatrix * H, GtsVector c)
+{
+  GtsTriangle * t = GTS_TRIANGLE (f);
+  GtsEdge * edge2;
+  GtsVertex * v1 = GTS_SEGMENT (edge)->v1, * v2 = GTS_SEGMENT (edge)->v2;
+  GtsPoint * p1, * p2;
+  GtsVector e, e3;
+
+  /* find orientation of segment */
+  edge2 = edge == t->e1 ? t->e2 : edge == t->e2 ? t->e3 : t->e1;
+  if (v2 != GTS_SEGMENT (edge2)->v1 && v2 != GTS_SEGMENT (edge2)->v2) {
+    v2 = v1; v1 = GTS_SEGMENT (edge)->v2;
+  }
+  p1 = GTS_POINT (v1);
+  p2 = GTS_POINT (v2);
+
+  e[0] = p2->x - p1->x;
+  e[1] = p2->y - p1->y;
+  e[2] = p2->z - p1->z;
+
+  e1[0] += e[0];
+  e1[1] += e[1];
+  e1[2] += e[2];
+
+  e3[0] = p2->y*p1->z - p2->z*p1->y;
+  e3[1] = p2->z*p1->x - p2->x*p1->z;
+  e3[2] = p2->x*p1->y - p2->y*p1->x;
+
+  e2[0] += e3[0];
+  e2[1] += e3[1];
+  e2[2] += e3[2];
+
+  H[0][0] += e[1]*e[1] + e[2]*e[2];
+  H[0][1] -= e[0]*e[1];
+  H[0][2] -= e[0]*e[2];
+  H[1][0] = H[0][1];
+  H[1][1] += e[0]*e[0] + e[2]*e[2];
+  H[1][2] -= e[1]*e[2];
+  H[2][0] = H[0][2];
+  H[2][1] = H[1][2];
+  H[2][2] += e[0]*e[0] + e[1]*e[1];
+
+  c[0] += e[1]*e3[2] - e[2]*e3[1];
+  c[1] += e[2]*e3[0] - e[0]*e3[2];
+  c[2] += e[0]*e3[1] - e[1]*e3[0];
+}
+
+static gdouble boundary_cost (GtsEdge * edge, 
+			      GtsFace * f,
+			      GtsVertex * v)
+{
+  GtsTriangle * t = GTS_TRIANGLE (f);
+  GtsEdge * edge2;
+  GtsVertex * v1 = GTS_SEGMENT (edge)->v1, * v2 = GTS_SEGMENT (edge)->v2;
+  GtsPoint * p1, * p2;
+  GtsVector e;
+  GtsPoint * p = GTS_POINT (v);
+
+  /* find orientation of segment */
+  edge2 = edge == t->e1 ? t->e2 : edge == t->e2 ? t->e3 : t->e1;
+  if (v2 != GTS_SEGMENT (edge2)->v1 && v2 != GTS_SEGMENT (edge2)->v2) {
+    v2 = v1; v1 = GTS_SEGMENT (edge)->v2;
+  }
+  p1 = GTS_POINT (v1);
+  p2 = GTS_POINT (v2);  
+
+  e[0] = (p2->y - p1->y)*(p->z - p2->z) - (p2->z - p1->z)*(p->y - p2->y);
+  e[1] = (p2->z - p1->z)*(p->x - p2->x) - (p2->x - p1->x)*(p->z - p2->z);
+  e[2] = (p2->x - p1->x)*(p->y - p2->y) - (p2->y - p1->y)*(p->x - p2->x);
+
+  return e[0]*e[0] + e[1]*e[1] + e[2]*e[2];
+}
+
+static gdouble edge_boundary_cost (GtsEdge * e, GtsVertex * v)
+{
+  gdouble cost = 0.;
+  GSList * i;
+
+  i = GTS_SEGMENT (e)->v1->segments;
+  while (i) {
+    GtsFace * f;
+    if (GTS_IS_EDGE (i->data) && 
+	(f = gts_edge_is_boundary (i->data, NULL)))
+      cost += boundary_cost (i->data, f, v);
+    i = i->next;
+  }
+  i = GTS_SEGMENT (e)->v2->segments;
+  while (i) {
+    GtsFace * f;
+    if (i->data != e && 
+	GTS_IS_EDGE (i->data) && 
+	(f = gts_edge_is_boundary (i->data, NULL)))
+      cost += boundary_cost (i->data, f, v);
+    i = i->next;
+  }
+
+  return cost/4.;
+}
+
+static gdouble edge_volume_cost (GtsEdge * e, GtsVertex * v)
+{
+  GSList * i, * triangles;
+  gdouble n1, n2, n3, nt;
+  gdouble cost = 0.0, a;
+
+  triangles = gts_vertex_triangles (GTS_SEGMENT (e)->v1, NULL);
+  triangles = gts_vertex_triangles (GTS_SEGMENT (e)->v2, triangles);
+
+  i = triangles;
+  while (i) {
+    if (GTS_IS_FACE (i->data)) {
+      triangle_normal (i->data, &n1, &n2, &n3, &nt);
+      a = GTS_POINT (v)->x*n1 + 
+	GTS_POINT (v)->y*n2 + 
+	GTS_POINT (v)->z*n3 - nt;
+      cost += a*a;
+    }
+    i = i->next;
+  }
+  g_slist_free (triangles);
+
+  return cost/36.;
+}
+
+static gdouble edge_shape_cost (GtsEdge * e, GtsVertex * v)
+{
+  GSList * list, * i;
+  GtsVertex 
+    * v1 = GTS_SEGMENT (e)->v1,
+    * v2 = GTS_SEGMENT (e)->v2;
+  gdouble cost = 0.;
+
+  list = gts_vertex_neighbors (v1, NULL, NULL);
+  list = gts_vertex_neighbors (v2, list, NULL);
+  i = list;
+  while (i) {
+    GtsPoint * p = i->data;
+    if (p != GTS_POINT (v1) && p != GTS_POINT (v2))
+      cost += gts_point_distance2 (p, GTS_POINT (v));
+    i = i->next;
+  }
+  g_slist_free (list);
+
+  return cost;
+}
+
+/**
+ * gts_volume_optimized_vertex:
+ * @edge: a #GtsEdge.
+ * @klass: a #GtsVertexClass to be used for the new vertex.
+ * @params: a #GtsVolumeOptimizedParms.
+ *
+ * Returns: a #GtsVertex which can be used to replace @edge for an
+ * edge collapse operation. The position of the vertex is optimized in
+ * order to minimize the changes in area and volume for the surface
+ * using @edge. The volume enclosed by the surface is locally
+ * preserved. For more details see "Fast and memory efficient
+ * polygonal simplification" (1998) and "Evaluation of memoryless
+ * simplification" (1999) by Lindstrom and Turk.  
+ */
+GtsVertex * gts_volume_optimized_vertex (GtsEdge * edge,
+					 GtsVertexClass * klass,
+					 GtsVolumeOptimizedParams * params)
+{
+  GSList * triangles, * i;
+  gdouble sn1 = 0., sn2 = 0., sn3 = 0.;
+  gdouble sn11 = 0., sn22 = 0., sn33 = 0.;
+  gdouble sn12 = 0., sn13 = 0., sn23 = 0.;
+  gdouble st = 0., stn1 = 0., stn2 = 0., stn3 = 0.;
+  gdouble n1, n2, n3, nt;
+  GtsMatrix * A, * Ai;
+  GtsVector A1, b;
+  GtsVector e1 = {0., 0., 0.}, e2 = {0., 0., 0.};
+  GtsMatrix * Hb;
+  GtsVector cb = {0., 0., 0.};
+  GtsVertex * v;
+  GtsVertex * v1, * v2;
+  guint n = 0, nb = 0;
+#ifdef DEBUG_VOPT
+  guint nold = 0;
+#endif
+
+  g_return_val_if_fail (edge != NULL, NULL);
+  g_return_val_if_fail (klass != NULL, NULL);
+  g_return_val_if_fail (params != NULL, NULL);
+
+  A = gts_matrix_zero (NULL);
+  Hb = gts_matrix_zero (NULL);
+  v1 = GTS_SEGMENT (edge)->v1;
+  v2 = GTS_SEGMENT (edge)->v2;
+
+  /* boundary preservation */
+  i = v1->segments;
+  while (i) {
+    GtsEdge * edge1 = i->data;
+    GtsFace * f;
+    if (GTS_IS_EDGE (edge1) &&
+	(f = gts_edge_is_boundary (edge1, NULL))) {
+      boundary_preservation (edge1, f, e1, e2, Hb, cb);
+      nb++;
+    }
+    i = i->next;
+  }
+  i = v2->segments;
+  while (i) {
+    GtsEdge * edge1 = i->data;
+    GtsFace * f;
+    if (edge1 != edge && 
+	GTS_IS_EDGE (edge1) &&
+	(f = gts_edge_is_boundary (edge1, NULL))) {
+      boundary_preservation (edge1, f, e1, e2, Hb, cb);
+      nb++;
+    }
+    i = i->next;
+  }
+  if (nb > 0) {
+    GtsMatrix * H = gts_matrix_new (
+	       e1[2]*e1[2] + e1[1]*e1[1], - e1[0]*e1[1], - e1[0]*e1[2], 0.,
+	       - e1[0]*e1[1], e1[2]*e1[2] + e1[0]*e1[0], - e1[1]*e1[2], 0.,
+	       - e1[0]*e1[2], - e1[1]*e1[2], e1[1]*e1[1] + e1[0]*e1[0], 0.,
+	       0., 0., 0., 0.);
+    GtsVector c;
+
+    c[0] = e1[1]*e2[2] - e1[2]*e2[1];
+    c[1] = e1[2]*e2[0] - e1[0]*e2[2];
+    c[2] = e1[0]*e2[1] - e1[1]*e2[0];
+    n = gts_matrix_quadratic_optimization (A, b, n, H, c);
+    gts_matrix_destroy (H);
+  }
+
+  g_assert (n <= 2);
+
+#ifdef DEBUG_VOPT
+  if (n != nold) {
+    fprintf (stderr, "--- boundary preservation ---\n");
+    gts_matrix_print (A, stderr);
+    gts_vector_print (b, stderr);
+    nold = n;
+  }
+#endif
+
+  /* volume preservation */
+  triangles = gts_vertex_triangles (v1, NULL);
+  triangles = gts_vertex_triangles (v2, triangles);
+
+  i = triangles;
+  while (i) {
+    if (GTS_IS_FACE (i->data)) {
+      triangle_normal (i->data, &n1, &n2, &n3, &nt);
+      sn1 += n1; sn2 += n2; sn3 += n3;
+      sn11 += n1*n1; sn22 += n2*n2; sn33 += n3*n3;
+      sn12 += n1*n2; sn13 += n1*n3; sn23 += n2*n3;
+      st += nt; stn1 += nt*n1; stn2 += nt*n2; stn3 += nt*n3;
+    }
+    i = i->next;
+  }
+  g_slist_free (triangles);
+
+  A1[0] = sn1; A1[1] = sn2; A1[2] = sn3;
+  n = gts_matrix_compatible_row (A, b, n, A1, st);
+
+#ifdef DEBUG_VOPT
+  if (n != nold) {
+    fprintf (stderr, "--- volume preservation ---\n");
+    gts_matrix_print (A, stderr);
+    gts_vector_print (b, stderr);
+    nold = n;
+  }
+#endif
+
+#if 1 /* Weighted average of volume and boundary optimization */
+  if (n < 3) {
+    /* volume optimization and boundary optimization */
+    GtsMatrix * H = gts_matrix_new (sn11, sn12, sn13, 0.,
+				    sn12, sn22, sn23, 0.,
+				    sn13, sn23, sn33, 0.,
+				    0., 0., 0., 0.);
+    GtsVector c;
+    gdouble le = 9.*params->boundary_weight*
+      gts_point_distance2 (GTS_POINT (v1), 
+			   GTS_POINT (v2));
+    guint i, j;
+
+    c[0] = - stn1; c[1] = - stn2; c[2] = - stn3;
+    if (nb > 0)
+      for (i = 0; i < 3; i++) {
+	for (j = 0; j < 3; j++)
+	  H[i][j] = params->volume_weight*H[i][j] + le*Hb[i][j];
+	c[i] = params->volume_weight*c[i] + le*cb[i];
+      }
+    n = gts_matrix_quadratic_optimization (A, b, n, H, c);
+    gts_matrix_destroy (H);
+  }
+
+#ifdef DEBUG_VOPT
+  if (n != nold) {
+    fprintf (stderr, "--- volume and boundary optimization ---\n");
+    gts_matrix_print (A, stderr);
+    gts_vector_print (b, stderr);
+    nold = n;
+  }
+#endif
+
+  if (n < 3) {
+    /* triangle shape optimization */
+    gdouble nv = 0.0;
+    GtsMatrix * H;
+    GtsVector c = {0., 0., 0.};
+    GSList * list, * i;
+
+    list = gts_vertex_neighbors (v1, NULL, NULL);
+    list = gts_vertex_neighbors (v2, list, NULL);
+
+    i = list;
+    while (i) {
+      GtsPoint * p1 = i->data;
+      if (p1 != GTS_POINT (v1) && p1 != GTS_POINT (v2)) {
+	nv += 1.0;
+	c[0] -= p1->x;
+	c[1] -= p1->y;
+	c[2] -= p1->z;
+      }
+      i = i->next;
+    }
+    g_slist_free (list);
+    
+    H = gts_matrix_new (nv, 0., 0., 0.,
+			0., nv, 0., 0.,
+			0., 0., nv, 0.,
+			0., 0., 0., 0.);
+    n = gts_matrix_quadratic_optimization (A, b, n, H, c);
+    gts_matrix_destroy (H);
+  }
+
+#ifdef DEBUG_VOPT
+  if (n != nold) {
+    fprintf (stderr, "--- triangle shape optimization ---\n");
+    gts_matrix_print (A, stderr);
+    gts_vector_print (b, stderr);
+    nold = n;
+  }
+#endif
+#else /* Weighted average of volume, boundary and shape optimization */
+  if (n < 3) {
+    /* volume optimization, boundary and shape optimization */
+    GtsMatrix * H; 
+    GtsVector c;
+    gdouble l2 = gts_point_distance2 (GTS_POINT (v1), 
+				      GTS_POINT (v2));
+    gdouble wv = params->volume_weight/32.;
+    gdouble wb = params->boundary_weight/4.*l2;
+    gdouble ws = params->shape_weight*l2*l2;
+    
+    gdouble nv = 0.0;
+    GtsVector cs = {0., 0., 0.};
+    GSList * list, * i;
+
+    list = gts_vertex_neighbors (v1, NULL, NULL);
+    list = gts_vertex_neighbors (v2, list, NULL);
+
+    i = list;
+    while (i) {
+      GtsPoint * p1 = i->data;
+      if (p1 != GTS_POINT (v1) && p1 != GTS_POINT (v2)) {
+	nv += 1.0;
+	cs[0] -= p1->x;
+	cs[1] -= p1->y;
+	cs[2] -= p1->z;
+      }
+      i = i->next;
+    }
+    g_slist_free (list);
+
+    H = gts_matrix_new (wv*sn11 + wb*Hb[0][0] + ws*nv, 
+			wv*sn12 + wb*Hb[0][1], 
+			wv*sn13 + wb*Hb[0][2],
+			wv*sn12 + wb*Hb[1][0], 
+			wv*sn22 + wb*Hb[1][1] + ws*nv, 
+			wv*sn23 + wb*Hb[1][2],
+			wv*sn13 + wb*Hb[2][0], 
+			wv*sn23 + wb*Hb[2][1], 
+			wv*sn33 + wb*Hb[2][2] + ws*nv);
+
+    c[0] = - wv*stn1 + wb*cb[0] + ws*cs[0];
+    c[1] = - wv*stn2 + wb*cb[1] + ws*cs[1];
+    c[2] = - wv*stn3 + wb*cb[2] + ws*cs[2];
+
+    n = gts_matrix_quadratic_optimization (A, b, n, H, c);
+    gts_matrix_destroy (H);
+  }
+
+#ifdef DEBUG_VOPT
+  if (n != nold) {
+    fprintf (stderr, "--- volume, boundary and shape optimization ---\n");
+    gts_matrix_print (A, stderr);
+    gts_vector_print (b, stderr);
+    nold = n;
+  }
+#endif
+#endif /* Weighted average of volume, boundary and shape optimization */
+
+  g_assert (n == 3);
+  g_assert ((Ai = gts_matrix3_inverse (A)));
+
+  v = gts_vertex_new (klass,
+		      Ai[0][0]*b[0] + Ai[0][1]*b[1] + Ai[0][2]*b[2],
+		      Ai[1][0]*b[0] + Ai[1][1]*b[1] + Ai[1][2]*b[2],
+		      Ai[2][0]*b[0] + Ai[2][1]*b[1] + Ai[2][2]*b[2]);
+
+  gts_matrix_destroy (A);
+  gts_matrix_destroy (Ai);
+  gts_matrix_destroy (Hb);
+  
+  return v;
+}
+
+/**
+ * gts_volume_optimized_cost:
+ * @e: a #GtsEdge.
+ * @params: a #GtsVolumeOptimizedParams.
+ * 
+ * Returns: the cost for the collapse of @e as minimized by the function
+ * gts_volume_optimized_vertex().
+ */
+gdouble gts_volume_optimized_cost (GtsEdge * e, 
+				   GtsVolumeOptimizedParams * params)
+{
+  GtsVertex * v;
+  gdouble cost;
+  gdouble length2;
+
+  g_return_val_if_fail (e != NULL, G_MAXDOUBLE);
+  g_return_val_if_fail (params != NULL, G_MAXDOUBLE);
+
+  v = gts_volume_optimized_vertex (e, gts_vertex_class (), params);
+
+  length2 = gts_point_distance2 (GTS_POINT (GTS_SEGMENT (e)->v1), 
+				 GTS_POINT (GTS_SEGMENT (e)->v2));
+  cost = 
+    params->volume_weight*edge_volume_cost (e, v) +
+    params->boundary_weight*length2*edge_boundary_cost (e, v) +
+    params->shape_weight*length2*length2*edge_shape_cost (e, v);
+  gts_object_destroy (GTS_OBJECT (v));
+
+  return cost;
+}
diff --git a/src/Makefile.am b/src/Makefile.am
index e287ae7..34c672d 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -4,6 +4,9 @@
 
 SUBDIRS=	icons
 
+CC = @CC_OR_CXX@
+CFLAGS = @CC_OR_CXX_FLAGS@
+
 pcbtreedir=	@PCBTREEDIR@
 pcblibdir=	@PCBLIBDIR@
 
@@ -12,7 +15,7 @@ HIDLIST = @HIDLIST@
 noinst_LIBRARIES = @HIDLIBS@
 EXTRA_LIBRARIES = \
 	libgtk.a liblesstif.a libbatch.a \
-	liblpr.a libgerber.a libbom.a libpng.a libps.a libnelma.a libgts.a \
+	liblpr.a libgerber.a libbom.a libpng.a libps.a libnelma.a \
 	libgcode.a
 
 pcblib_DATA=	\
@@ -181,9 +184,8 @@ pcb_DEPENDENCIES = @HIDLIBS@
 
 if WITH_TOPOROUTER
 PCB_SRCS += toporouter.c toporouter.h
-noinst_LIBRARIES += libgts.a
-pcb_LDADD += libgts.a
-pcb_DEPENDENCIES += libgts.a
+pcb_LDADD += ../gts/libgts.a
+pcb_DEPENDENCIES += ../gts/libgts.a
 endif
 
 pcb_SOURCES = ${PCB_SRCS} core_lists.h
@@ -195,7 +197,7 @@ core_lists.h : ${PCB_SRCS} Makefile
 	mv $@.tmp $@
 
 # for globalconst.h
-INCLUDES=	-I$(top_srcdir) -I$(srcdir)/icons -I$(srcdir)/gts
+INCLUDES=	-I$(top_srcdir) -I$(srcdir)/icons -I$(srcdir)/../gts
 
 DEFS= 	-DLOCALEDIR=\"$(localedir)\" @DEFS@
 
@@ -328,56 +330,6 @@ hid/lesstif/lesstif_lists.h : ${LIBLESSTIF_SRCS} Makefile
 	(for f in ${LIBLESSTIF_SRCS} ; do cat $(srcdir)/$$f ; done) | grep "^REGISTER" > $@.tmp
 	mv $@.tmp $@
 
-libgts_a_CPPFLAGS = -I./gts
-LIBGTS_SRCS = \
-	gts/object.c \
-	gts/point.c \
-	gts/vertex.c \
-	gts/segment.c \
-	gts/edge.c \
-	gts/triangle.c \
-	gts/face.c \
-	gts/kdtree.c \
-	gts/bbtree.c \
-	gts/misc.c \
-	gts/gts-private.h \
-	gts/predicates.c \
-	gts/predicates.h \
-	gts/rounding.h \
-	gts/heap.c \
-	gts/eheap.c \
-	gts/fifo.c \
-	gts/gts.h \
-	gts/matrix.c \
-	gts/surface.c \
-	gts/stripe.c \
-	gts/vopt.c \
-	gts/refine.c \
-	gts/iso.c \
-	gts/isotetra.c \
-	gts/split.c \
-	gts/psurface.c \
-	gts/hsurface.c \
-	gts/cdt.c \
-	gts/boolean.c \
-	gts/named.c \
-	gts/oocs.c \
-	gts/container.c \
-	gts/graph.c \
-	gts/pgraph.c \
-	gts/partition.c \
-	gts/curvature.c \
-	gts/tribox3.c
-libgts_a_SOURCES = ${LIBGTS_SRCS} gts/gts_lists.h
- 
-gts/gts_lists.h : ${LIBGTS_SRCS} Makefile
-	$(MKDIR_P) gts
-	true > $@
-# Uncomment out the following if/when we ever end up with REGISTER in any of the gts
-# source files.  For now, there aren't any and so the grep fails and make stops
-#	(for f in ${LIBGTS_SRCS} ; do cat $(srcdir)/$$f ; done) | grep "^REGISTER" > $@.tmp
-#	mv $@.tmp $@
-
 libbatch_a_CPPFLAGS = -I./hid/batch
 LIBBATCH_SRCS = \
 	hid/hidint.h \
@@ -478,7 +430,6 @@ DISTCLEANFILES= pcbtest.sh gpcb-menu.h pcb-menu.h \
 	hid/gcode/gcode_lists.h \
 	hid/nelma/nelma_lists.h \
 	hid/ps/ps_lists.h \
-	gts/gts_lists.h \
 	core_lists.h \
 	dbus-introspect.h
 
diff --git a/src/gts/.gitignore b/src/gts/.gitignore
deleted file mode 100644
index 8e051a6..0000000
--- a/src/gts/.gitignore
+++ /dev/null
@@ -1,2 +0,0 @@
-.dirstamp
-predicates_init.h
diff --git a/src/gts/NOTES b/src/gts/NOTES
deleted file mode 100644
index c697949..0000000
--- a/src/gts/NOTES
+++ /dev/null
@@ -1,3 +0,0 @@
-- hsurface may create surfaces with duplicates edges and triangles (because of 
- collapses of "empty triangles").
-- psurface however will not.
diff --git a/src/gts/bbtree.c b/src/gts/bbtree.c
deleted file mode 100644
index cec93e4..0000000
--- a/src/gts/bbtree.c
+++ /dev/null
@@ -1,1289 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <math.h>
-#include "gts.h"
-
-static void bbox_init (GtsBBox * bbox)
-{
-  bbox->bounded = NULL;
-}
-
-/**
- * gts_bbox_class:
- *
- * Returns: the #GtsBBoxClass.
- */
-GtsBBoxClass * gts_bbox_class (void)
-{
-  static GtsBBoxClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo bbox_info = {
-      "GtsBBox",
-      sizeof (GtsBBox),
-      sizeof (GtsBBoxClass),
-      (GtsObjectClassInitFunc) NULL,
-      (GtsObjectInitFunc) bbox_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (gts_object_class (), &bbox_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_bbox_set:
- * @bbox: a #GtsBBox.
- * @bounded: the object to be bounded.
- * @x1: x-coordinate of the lower left corner.
- * @y1: y-coordinate of the lower left corner.
- * @z1: z-coordinate of the lower left corner.
- * @x2: x-coordinate of the upper right corner.
- * @y2: y-coordinate of the upper right corner.
- * @z2: z-coordinate of the upper right corner.
- *
- * Sets fields of @bbox.
- */
-void gts_bbox_set (GtsBBox * bbox,
-		   gpointer bounded,
-		   gdouble x1, gdouble y1, gdouble z1,
-		   gdouble x2, gdouble y2, gdouble z2)
-{
-  g_return_if_fail (bbox != NULL);
-  g_return_if_fail (x2 >= x1 && y2 >= y1 && z2 >= z1);
-
-  bbox->x1 = x1; bbox->y1 = y1; bbox->z1 = z1;
-  bbox->x2 = x2; bbox->y2 = y2; bbox->z2 = z2;
-  bbox->bounded = bounded;
-}
-
-/**
- * gts_bbox_new:
- * @klass: a #GtsBBoxClass.
- * @bounded: the object to be bounded.
- * @x1: x-coordinate of the lower left corner.
- * @y1: y-coordinate of the lower left corner.
- * @z1: z-coordinate of the lower left corner.
- * @x2: x-coordinate of the upper right corner.
- * @y2: y-coordinate of the upper right corner.
- * @z2: z-coordinate of the upper right corner.
- *
- * Returns: a new #GtsBBox.
- */
-GtsBBox * gts_bbox_new (GtsBBoxClass * klass,
-			gpointer bounded,
-			gdouble x1, gdouble y1, gdouble z1,
-			gdouble x2, gdouble y2, gdouble z2)
-{
-  GtsBBox * bbox;
-
-  g_return_val_if_fail (klass != NULL, NULL);
-
-  bbox = GTS_BBOX (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  gts_bbox_set (bbox, bounded, x1, y1, z1, x2, y2, z2);
-  return bbox;
-}
-
-/**
- * gts_bbox_triangle:
- * @klass: a #GtsBBoxClass.
- * @t: a #GtsTriangle.
- *
- * Returns: a new #GtsBBox bounding box of @t.
- */
-GtsBBox * gts_bbox_triangle (GtsBBoxClass * klass,
-			     GtsTriangle * t)
-{
-  GtsBBox * bbox;
-  GtsPoint * p;
-
-  g_return_val_if_fail (t != NULL, NULL);
-  g_return_val_if_fail (klass != NULL, NULL);
-
-  p = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
-  bbox = gts_bbox_new (klass, t, p->x, p->y, p->z, p->x, p->y, p->z);
-
-  p = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
-  if (p->x > bbox->x2) bbox->x2 = p->x;
-  if (p->x < bbox->x1) bbox->x1 = p->x;
-  if (p->y > bbox->y2) bbox->y2 = p->y;
-  if (p->y < bbox->y1) bbox->y1 = p->y;
-  if (p->z > bbox->z2) bbox->z2 = p->z;
-  if (p->z < bbox->z1) bbox->z1 = p->z;
-  p = GTS_POINT (gts_triangle_vertex (t));
-  if (p->x > bbox->x2) bbox->x2 = p->x;
-  if (p->x < bbox->x1) bbox->x1 = p->x;
-  if (p->y > bbox->y2) bbox->y2 = p->y;
-  if (p->y < bbox->y1) bbox->y1 = p->y;
-  if (p->z > bbox->z2) bbox->z2 = p->z;
-  if (p->z < bbox->z1) bbox->z1 = p->z;
-  
-  return bbox;
-}
-
-/**
- * gts_bbox_segment:
- * @klass: a #GtsBBoxClass.
- * @s: a #GtsSegment.
- * 
- * Returns: a new #GtsBBox bounding box of @s.
- */
-GtsBBox * gts_bbox_segment (GtsBBoxClass * klass, GtsSegment * s)
-{
-  GtsBBox * bbox;
-  GtsPoint * p1, * p2;
-
-  g_return_val_if_fail (s != NULL, NULL);
-  g_return_val_if_fail (klass != NULL, NULL);
-
-  bbox = gts_bbox_new (klass, s, 0., 0., 0., 0., 0., 0.);
-
-  p1 = GTS_POINT (s->v1); 
-  p2 = GTS_POINT (s->v2);
-  if (p1->x > p2->x) {
-    bbox->x2 = p1->x; bbox->x1 = p2->x;
-  }
-  else {
-    bbox->x1 = p1->x; bbox->x2 = p2->x;
-  }
-  if (p1->y > p2->y) {
-    bbox->y2 = p1->y; bbox->y1 = p2->y;
-  }
-  else {
-    bbox->y1 = p1->y; bbox->y2 = p2->y;
-  }
-  if (p1->z > p2->z) {
-    bbox->z2 = p1->z; bbox->z1 = p2->z;
-  }
-  else {
-    bbox->z1 = p1->z; bbox->z2 = p2->z;
-  }
-
-  return bbox;
-}
-
-static void bbox_foreach_vertex (GtsPoint * p, GtsBBox * bb)
-{
-  if (p->x < bb->x1) bb->x1 = p->x;
-  if (p->y < bb->y1) bb->y1 = p->y;
-  if (p->z < bb->z1) bb->z1 = p->z;
-  if (p->x > bb->x2) bb->x2 = p->x;
-  if (p->y > bb->y2) bb->y2 = p->y;
-  if (p->z > bb->z2) bb->z2 = p->z;
-}
-
-/**
- * gts_bbox_surface:
- * @klass: a #GtsBBoxClass.
- * @surface: a #GtsSurface.
- *
- * Returns: a new #GtsBBox bounding box of @surface.
- */
-GtsBBox * gts_bbox_surface (GtsBBoxClass * klass, GtsSurface * surface)
-{
-  GtsBBox * bbox;
-
-  g_return_val_if_fail (klass != NULL, NULL);
-  g_return_val_if_fail (surface != NULL, NULL);
-
-  bbox = gts_bbox_new (klass, surface, 0., 0., 0., 0., 0., 0.);
-  bbox->x1 = bbox->y1 = bbox->z1 = G_MAXDOUBLE;
-  bbox->x2 = bbox->y2 = bbox->z2 = -G_MAXDOUBLE;
-
-  gts_surface_foreach_vertex (surface, (GtsFunc) bbox_foreach_vertex, bbox);
-
-  return bbox;
-}
-
-/**
- * gts_bbox_bboxes:
- * @klass: a #GtsBBoxClass.
- * @bboxes: a list of #GtsBBox.
- * 
- * Returns: a new #GtsBBox bounding box of all the bounding boxes in
- * @bboxes.  
- */
-GtsBBox * gts_bbox_bboxes (GtsBBoxClass * klass, GSList * bboxes)
-{
-  GtsBBox * bbox;
-  GtsBBox * bb;
-
-  g_return_val_if_fail (bboxes != NULL, NULL);
-  g_return_val_if_fail (klass != NULL, NULL);
-
-  bb = bboxes->data;
-  bbox = gts_bbox_new (klass, bboxes, 
-		       bb->x1, bb->y1, bb->z1, bb->x2, bb->y2, bb->z2);
-  bboxes = bboxes->next;
-  while (bboxes) {
-    bb = bboxes->data;
-    if (bb->x1 < bbox->x1) bbox->x1 = bb->x1;
-    if (bb->y1 < bbox->y1) bbox->y1 = bb->y1;
-    if (bb->z1 < bbox->z1) bbox->z1 = bb->z1;
-    if (bb->x2 > bbox->x2) bbox->x2 = bb->x2;
-    if (bb->y2 > bbox->y2) bbox->y2 = bb->y2;
-    if (bb->z2 > bbox->z2) bbox->z2 = bb->z2;
-    bboxes = bboxes->next;
-  }
-
-  return bbox;
-}
-
-/**
- * gts_bbox_points:
- * @klass: a #GtsBBoxClass.
- * @points: a list of #GtsPoint.
- *
- * Returns: a new #GtsBBox bounding box of @points.
- */
-GtsBBox * gts_bbox_points (GtsBBoxClass * klass, GSList * points)
-{
-  GtsPoint * p;
-  GtsBBox * bbox;
-  GSList * i;
-
-  if (points == NULL) 
-    return NULL;
-
-  p = points->data;  
-  bbox = gts_bbox_new (klass, points, p->x, p->y, p->z, p->x, p->y, p->z);
-
-  i = points->next;
-  while (i) {
-    p = i->data;
-    if (p->x > bbox->x2) 
-      bbox->x2 = p->x;
-    else if (p->x < bbox->x1) 
-      bbox->x1 = p->x;
-    if (p->y > bbox->y2) 
-      bbox->y2 = p->y;
-    else if (p->y < bbox->y1) 
-      bbox->y1 = p->y;
-    if (p->z > bbox->z2) 
-      bbox->z2 = p->z;
-    else if (p->z < bbox->z1) 
-      bbox->z1 = p->z;
-    i = i->next;
-  }
-  
-  return bbox;
-}
-
-/**
- * gts_bboxes_are_overlapping:
- * @bb1: a #GtsBBox.
- * @bb2: a #GtsBBox.
- *
- * Returns: %TRUE if the bounding boxes @bb1 and @bb2 are overlapping
- * (including just touching), %FALSE otherwise.
- */
-gboolean gts_bboxes_are_overlapping (GtsBBox * bb1, GtsBBox * bb2)
-{
-  if (bb1 == bb2)
-    return TRUE;
-  if (bb1->x1 > bb2->x2)
-    return FALSE;
-  if (bb2->x1 > bb1->x2)
-    return FALSE;
-  if (bb1->y1 > bb2->y2)
-    return FALSE;
-  if (bb2->y1 > bb1->y2)
-    return FALSE;
-  if (bb1->z1 > bb2->z2)
-    return FALSE;
-  if (bb2->z1 > bb1->z2)
-    return FALSE;  
-  return TRUE;
-}
-
-#define bbox_volume(bb) (((bb)->x2 -\
-                          (bb)->x1)*\
-                         ((bb)->y2 -\
-                          (bb)->y1)*\
-                         ((bb)->z2 -\
-                          (bb)->z1))
-
-/**
- * gts_bbox_diagonal2:
- * @bb: a #GtsBBox.
- *
- * Returns: the squared length of the diagonal of @bb.
- */
-gdouble gts_bbox_diagonal2 (GtsBBox * bb)
-{
-  gdouble x, y, z;
-
-  g_return_val_if_fail (bb != NULL, 0.);
-
-  x = bb->x2 - bb->x1;
-  y = bb->y2 - bb->y1;
-  z = bb->z2 - bb->z1;
-
-  return x*x + y*y + z*z;
-}
-
-/**
- * gts_bbox_draw:
- * @bb: a #GtsBBox.
- * @fptr: a file pointer.
- * 
- * Writes in file @fptr an OOGL (Geomview) description of @bb.
- */
-void gts_bbox_draw (GtsBBox * bb, FILE * fptr)
-{
-  g_return_if_fail (bb != NULL);
-
-  fprintf (fptr, "OFF 8 6 12\n");
-  fprintf (fptr, "%g %g %g\n",
-	   bb->x1, bb->y1, bb->z1);
-  fprintf (fptr, "%g %g %g\n",
-	   bb->x2, bb->y1, bb->z1);
-  fprintf (fptr, "%g %g %g\n",
-	   bb->x2, bb->y2, bb->z1);
-  fprintf (fptr, "%g %g %g\n",
-	   bb->x1, bb->y2, bb->z1);
-  fprintf (fptr, "%g %g %g\n",
-	   bb->x1, bb->y1, bb->z2);
-  fprintf (fptr, "%g %g %g\n",
-	   bb->x2, bb->y1, bb->z2);
-  fprintf (fptr, "%g %g %g\n",
-	   bb->x2, bb->y2, bb->z2);
-  fprintf (fptr, "%g %g %g\n",
-	   bb->x1, bb->y2, bb->z2);
-  fputs ("4 3 2 1 0\n"
-	 "4 4 5 6 7\n"
-	 "4 2 3 7 6\n"
-	 "4 0 1 5 4\n"
-	 "4 0 4 7 3\n"
-	 "4 1 2 6 5\n",
-	 fptr);
-}
-
-#define MINMAX(x1, x2, xmin, xmax) { if (x1 < x2) { xmin = x1; xmax = x2; }\
-                                     else { xmin = x2; xmax = x1; } }
-
-/**
- * gts_bbox_point_distance2:
- * @bb: a #GtsBBox.
- * @p: a #GtsPoint.
- * @min: a pointer on a gdouble.
- * @max: a pointer on a gdouble.
- * 
- * Sets @min and @max to lower and upper bounds for the square of the
- * Euclidean distance between the object contained in @bb and @p. For these
- * bounds to make any sense the bounding box must be "tight" i.e. each of the
- * 6 faces of the box must at least be touched by one point of the bounded
- * object.
- */
-void gts_bbox_point_distance2 (GtsBBox * bb, GtsPoint * p,
-			       gdouble * min, gdouble * max)
-{
-  gdouble x1, y1, z1, x2, y2, z2, x, y, z;
-  gdouble dmin, dmax, xd1, xd2, yd1, yd2, zd1, zd2;
-  gdouble mx, Mx, my, My, mz, Mz;
-    
-  g_return_if_fail (bb != NULL);
-  g_return_if_fail (p != NULL);
-  g_return_if_fail (min != NULL);
-  g_return_if_fail (max != NULL);
-
-  x1 = bb->x1; y1 = bb->y1; z1 = bb->z1; 
-  x2 = bb->x2; y2 = bb->y2; z2 = bb->z2;
-  x = p->x; y = p->y; z = p->z;
-
-  xd1 = (x1 - x)*(x1 - x);
-  xd2 = (x - x2)*(x - x2);
-  yd1 = (y1 - y)*(y1 - y);
-  yd2 = (y - y2)*(y - y2);
-  zd1 = (z1 - z)*(z1 - z);
-  zd2 = (z - z2)*(z - z2);
-  
-  dmin = x < x1 ? xd1 : x > x2 ? xd2 : 0.0;
-  dmin += y < y1 ? yd1 : y > y2 ? yd2 : 0.0;
-  dmin += z < z1 ? zd1 : z > z2 ? zd2 : 0.0;
-
-  MINMAX (xd1, xd2, mx, Mx);
-  MINMAX (yd1, yd2, my, My);
-  MINMAX (zd1, zd2, mz, Mz);
-  
-  dmax = mx + My + Mz;
-  dmax = MIN (dmax, Mx + my + Mz);
-  dmax = MIN (dmax, Mx + My + mz);
-  
-  *min = dmin;
-  *max = dmax;
-}
-
-/**
- * gts_bbox_is_stabbed:
- * @bb: a #GtsBBox.
- * @p: a #GtsPoint.
- *
- * Returns: %TRUE if the ray starting at @p and ending at (+infty,
- * @p->y, @p->z) intersects with @bb, %FALSE otherwise.
- */
-gboolean gts_bbox_is_stabbed (GtsBBox * bb, GtsPoint * p)
-{
-  g_return_val_if_fail (bb != NULL, FALSE);
-  g_return_val_if_fail (p != NULL, FALSE);
-
-  if (p->x > bb->x2 ||
-      p->y < bb->y1 || p->y > bb->y2 ||
-      p->z < bb->z1 || p->z > bb->z2)
-    return FALSE;
-  return TRUE;
-}
-
-extern int triBoxOverlap (double boxcenter[3],
-			  double boxhalfsize[3],
-			  double triverts[3][3]);
-
-/**
- * gts_bbox_overlaps_triangle:
- * @bb: a #GtsBBox.
- * @t: a #GtsTriangle.
- *
- * This is a wrapper around the fast overlap test of Tomas
- * Akenine-Moller (http://www.cs.lth.se/home/Tomas_Akenine_Moller/).
- *
- * Returns: %TRUE if @bb overlaps with @t, %FALSE otherwise.
- */
-gboolean gts_bbox_overlaps_triangle (GtsBBox * bb, GtsTriangle * t)
-{
-  double bc[3], bh[3], tv[3][3];
-  GtsPoint * p1, * p2, * p3;
-
-  g_return_val_if_fail (bb != NULL, FALSE);
-  g_return_val_if_fail (t != NULL, FALSE);
-
-  bc[0] = (bb->x2 + bb->x1)/2.;
-  bh[0] = (bb->x2 - bb->x1)/2.;
-  bc[1] = (bb->y2 + bb->y1)/2.;
-  bh[1] = (bb->y2 - bb->y1)/2.;
-  bc[2] = (bb->z2 + bb->z1)/2.;
-  bh[2] = (bb->z2 - bb->z1)/2.;
-  p1 = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
-  p2 = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
-  p3 = GTS_POINT (gts_triangle_vertex (t));
-  tv[0][0] = p1->x; tv[0][1] = p1->y; tv[0][2] = p1->z;
-  tv[1][0] = p2->x; tv[1][1] = p2->y; tv[1][2] = p2->z;
-  tv[2][0] = p3->x; tv[2][1] = p3->y; tv[2][2] = p3->z;
-
-  return triBoxOverlap (bc, bh, tv);
-}
-
-/**
- * gts_bbox_overlaps_segment:
- * @bb: a #GtsBBox.
- * @s: a #GtsSegment.
- *
- * This functions uses gts_bbox_overlaps_triangle() with a degenerate
- * triangle.
- *
- * Returns: %TRUE if @bb overlaps with @s, %FALSE otherwise.
- */
-gboolean gts_bbox_overlaps_segment (GtsBBox * bb, GtsSegment * s)
-{
-  double bc[3], bh[3], tv[3][3];
-  GtsPoint * p1, * p2, * p3;
-
-  g_return_val_if_fail (bb != NULL, FALSE);
-  g_return_val_if_fail (s != NULL, FALSE);
-
-  bc[0] = (bb->x2 + bb->x1)/2.;
-  bh[0] = (bb->x2 - bb->x1)/2.;
-  bc[1] = (bb->y2 + bb->y1)/2.;
-  bh[1] = (bb->y2 - bb->y1)/2.;
-  bc[2] = (bb->z2 + bb->z1)/2.;
-  bh[2] = (bb->z2 - bb->z1)/2.;
-  p1 = GTS_POINT (s->v1);
-  p2 = GTS_POINT (s->v2);
-  p3 = p1;
-  tv[0][0] = p1->x; tv[0][1] = p1->y; tv[0][2] = p1->z;
-  tv[1][0] = p2->x; tv[1][1] = p2->y; tv[1][2] = p2->z;
-  tv[2][0] = p3->x; tv[2][1] = p3->y; tv[2][2] = p3->z;
-
-  return triBoxOverlap (bc, bh, tv);
-}
-
-/**
- * gts_bb_tree_new:
- * @bboxes: a list of #GtsBBox.
- *
- * Builds a new hierarchy of bounding boxes for @bboxes. At each
- * level, the GNode->data field contains a #GtsBBox bounding box of
- * all the children. The tree is binary and is built by repeatedly
- * cutting in two approximately equal halves the bounding boxes at
- * each level until a leaf node (i.e. a bounding box given in @bboxes)
- * is reached. In order to minimize the depth of the tree, the cutting
- * direction is always chosen as perpendicular to the longest
- * dimension of the bounding box.
- *
- * Returns: a new hierarchy of bounding boxes.  
- */
-GNode * gts_bb_tree_new (GSList * bboxes)
-{
-  GSList * i, * positive = NULL, * negative = NULL;
-  GNode * node;
-  GtsBBox * bbox;
-  guint dir, np = 0, nn = 0;
-  gdouble * p1, * p2;
-  gdouble cut;
-  
-  g_return_val_if_fail (bboxes != NULL, NULL);
-
-  if (bboxes->next == NULL) /* leaf node */
-    return g_node_new (bboxes->data);
-
-  bbox = gts_bbox_bboxes (gts_bbox_class (), bboxes);
-  node = g_node_new (bbox);
-
-  if (bbox->x2 - bbox->x1 > bbox->y2 - bbox->y1) {
-    if (bbox->z2 - bbox->z1 > bbox->x2 - bbox->x1)
-      dir = 2;
-    else
-      dir = 0;
-  }
-  else if (bbox->z2 - bbox->z1 > bbox->y2 - bbox->y1)
-    dir = 2;
-  else
-    dir = 1;
-
-  p1 = (gdouble *) &bbox->x1;
-  p2 = (gdouble *) &bbox->x2;
-  cut = (p1[dir] + p2[dir])/2.;
-  i = bboxes;
-  while (i) {
-    bbox = i->data; 
-    p1 = (gdouble *) &bbox->x1;
-    p2 = (gdouble *) &bbox->x2;
-    if ((p1[dir] + p2[dir])/2. > cut) {
-      positive = g_slist_prepend (positive, bbox);
-      np++;
-    }
-    else {
-      negative = g_slist_prepend (negative, bbox);
-      nn++;
-    }
-    i = i->next;
-  }
-  if (!positive) {
-    GSList * last = g_slist_nth (negative, (nn - 1)/2);
-    positive = last->next;
-    last->next = NULL;
-  }
-  else if (!negative) {
-    GSList * last = g_slist_nth (positive, (np - 1)/2);
-    negative = last->next;
-    last->next = NULL;
-  }
-  g_node_prepend (node, gts_bb_tree_new (positive));
-  g_slist_free (positive);
-  g_node_prepend (node, gts_bb_tree_new (negative));
-  g_slist_free (negative);
-  
-  return node;
-}
-
-static void prepend_triangle_bbox (GtsTriangle * t, GSList ** bboxes)
-{
-  *bboxes = g_slist_prepend (*bboxes, 
-			     gts_bbox_triangle (gts_bbox_class (), t));
-}
-
-/**
- * gts_bb_tree_surface:
- * @s: a #GtsSurface.
- *
- * Returns: a new hierarchy of bounding boxes bounding the faces of @s.
- */
-GNode * gts_bb_tree_surface (GtsSurface * s)
-{
-  GSList * bboxes = NULL;
-  GNode * tree;
-
-  g_return_val_if_fail (s != NULL, NULL);
-
-  gts_surface_foreach_face (s, (GtsFunc) prepend_triangle_bbox, &bboxes);
-  tree = gts_bb_tree_new (bboxes);
-  g_slist_free (bboxes);
-
-  return tree;
-}
-
-/**
- * gts_bb_tree_stabbed:
- * @tree: a bounding box tree.
- * @p: a #GtsPoint.
- *
- * Returns: a list of bounding boxes, leaves of @tree which are
- * stabbed by the ray defined by @p (see gts_bbox_is_stabbed()).
- */
-GSList * gts_bb_tree_stabbed (GNode * tree, GtsPoint * p)
-{
-  GSList * list = NULL;
-  GtsBBox * bb;
-  GNode * i;
-
-  g_return_val_if_fail (tree != NULL, NULL);
-  g_return_val_if_fail (p != NULL, NULL);
-
-  bb = tree->data;
-  if (!gts_bbox_is_stabbed (bb, p))
-    return NULL;
-  if (tree->children == NULL) /* leaf node */
-    return g_slist_prepend (NULL, bb);
-  i = tree->children;
-  while (i) {
-    list = g_slist_concat (list, gts_bb_tree_stabbed (i, p));
-    i = i->next;
-  }
-  return list;
-}
-
-/**
- * gts_bb_tree_overlap:
- * @tree: a bounding box tree.
- * @bbox: a #GtsBBox.
- *
- * Returns: a list of bounding boxes, leaves of @tree which overlap @bbox.
- */
-GSList * gts_bb_tree_overlap (GNode * tree, GtsBBox * bbox)
-{
-  GSList * list = NULL;
-  GtsBBox * bb;
-  GNode * i;
-
-  g_return_val_if_fail (tree != NULL, NULL);
-  g_return_val_if_fail (bbox != NULL, NULL);
-
-  bb = tree->data;
-  if (!gts_bboxes_are_overlapping (bbox, bb))
-    return NULL;
-  if (tree->children == NULL) /* leaf node */
-    return g_slist_prepend (NULL, bb);
-  i = tree->children;
-  while (i) {
-    list = g_slist_concat (list, gts_bb_tree_overlap (i, bbox));
-    i = i->next;
-  }
-  return list;
-}
-
-/**
- * gts_bb_tree_is_overlapping:
- * @tree: a bounding box tree.
- * @bbox: a #GtsBBox.
- *
- * Returns: %TRUE if any leaf of @tree overlaps @bbox, %FALSE otherwise.
- */
-gboolean gts_bb_tree_is_overlapping (GNode * tree, GtsBBox * bbox)
-{
-  GtsBBox * bb;
-  GNode * i;
-
-  g_return_val_if_fail (tree != NULL, FALSE);
-  g_return_val_if_fail (bbox != NULL, FALSE);
-
-  bb = tree->data;
-  if (!gts_bboxes_are_overlapping (bbox, bb))
-    return FALSE;
-  if (tree->children == NULL) /* leaf node */
-    return TRUE;
-  i = tree->children;
-  while (i) {
-    if (gts_bb_tree_is_overlapping (i, bbox))
-      return TRUE;
-    i = i->next;
-  }
-  return FALSE;
-}
-
-/**
- * gts_bb_tree_traverse_overlapping:
- * @tree1: a bounding box tree.
- * @tree2: a bounding box tree.
- * @func: a #GtsBBTreeTraverseFunc.
- * @data: user data to be passed to @func.
- *
- * Calls @func for each overlapping pair of leaves of @tree1 and @tree2.
- */
-void gts_bb_tree_traverse_overlapping (GNode * tree1, GNode * tree2,
-				       GtsBBTreeTraverseFunc func,
-				       gpointer data)
-{
-  GtsBBox * bb1, * bb2;
-
-  g_return_if_fail (tree1 != NULL && tree2 != NULL);
-
-  bb1 = tree1->data; bb2 = tree2->data;
-  if (!gts_bboxes_are_overlapping (bb1, bb2))
-    return;
-
-  if (tree1->children == NULL && tree2->children == NULL)
-    (*func) (tree1->data, tree2->data, data);
-  else if (tree2->children == NULL || 
-	   (tree1->children != NULL && 
-	    bbox_volume (bb1) > bbox_volume (bb2))) {
-    GNode * i = tree1->children;
-    while (i) {
-      gts_bb_tree_traverse_overlapping (i, tree2, func, data);
-      i = i->next;
-    }
-  }
-  else {
-    GNode * i = tree2->children;
-    while (i) {
-      gts_bb_tree_traverse_overlapping (tree1, i, func, data);
-      i = i->next;
-    }
-  }
-}
-
-/**
- * gts_bb_tree_draw:
- * @tree: a bounding box tree.
- * @depth: a specified depth.
- * @fptr: a file pointer.
- *
- * Write in @fptr an OOGL (Geomview) description of @tree for the
- * depth specified by @depth.
- */
-void gts_bb_tree_draw (GNode * tree, guint depth, FILE * fptr)
-{
-  guint d;
-
-  g_return_if_fail (tree != NULL);
-  g_return_if_fail (fptr != NULL);
-
-  d = g_node_depth (tree);
-
-  if (d == 1)
-    fprintf (fptr, "{ LIST");
-
-  if (d == depth)
-    gts_bbox_draw (tree->data, fptr);
-  else if (d < depth) {
-    GNode * i = tree->children;
-    while (i) {
-      gts_bb_tree_draw (i, depth, fptr);
-      i = i->next;
-    }
-  }
-
-  if (d == 1)
-    fprintf (fptr, "}\n");
-}
-
-static void bb_tree_free (GNode * tree, gboolean free_leaves)
-{
-  GNode * i;
-
-  g_return_if_fail (tree != NULL);
-
-  if (!free_leaves && tree->children == NULL) /* leaf node */
-    return;
-
-  gts_object_destroy (tree->data);
-
-  i = tree->children;
-  while (i) {
-    bb_tree_free (i, free_leaves);
-    i = i->next;
-  }
-}
-
-/**
- * gts_bb_tree_destroy:
- * @tree: a bounding box tree.
- * @free_leaves: if %TRUE the bounding boxes given by the user are freed.
- *
- * Destroys all the bounding boxes created by @tree and destroys the
- * tree itself. If @free_leaves is set to %TRUE, destroys boxes given
- * by the user when creating the tree (i.e. leaves of the tree).  
- */
-void gts_bb_tree_destroy (GNode * tree, gboolean free_leaves)
-{
-  g_return_if_fail (tree != NULL);
-  
-  bb_tree_free (tree, free_leaves);
-  g_node_destroy (tree);
-}
-
-static gdouble bb_tree_min_max (GNode * tree,
-				GtsPoint * p,
-				gdouble min_max,
-				GSList ** list)
-{
-  GNode * tree1, * tree2;
-  gdouble min1, max1, min2, max2;
-
-  if (tree->children == NULL) {
-    *list = g_slist_prepend (*list, tree->data);
-    return min_max;
-  }
-  tree1 = tree->children;
-  gts_bbox_point_distance2 (tree1->data, p, &min1, &max1);
-  if (max1 < min_max)
-    min_max = max1;
-
-  tree2 = tree1->next;
-  gts_bbox_point_distance2 (tree2->data, p, &min2, &max2);
-  if (max2 < min_max)
-    min_max = max2;
-
-  if (min1 < min2) {
-    if (min1 <= min_max) {
-      min_max = bb_tree_min_max (tree1, p, min_max, list);
-      if (min2 <= min_max)
-	min_max = bb_tree_min_max (tree2, p, min_max, list);
-    }
-  }
-  else {
-    if (min2 <= min_max) {
-      min_max = bb_tree_min_max (tree2, p, min_max, list);
-      if (min1 <= min_max)
-	min_max = bb_tree_min_max (tree1, p, min_max, list);
-    }
-  }
-
-  return min_max;
-}
-
-/**
- * gts_bb_tree_point_closest_bboxes:
- * @tree: a bounding box tree.
- * @p: a #GtsPoint.
- *
- * Returns: a list of #GtsBBox. One of the bounding boxes is assured to contain
- * the object of @tree closest to @p.
- */
-GSList * gts_bb_tree_point_closest_bboxes (GNode * tree, 
-					   GtsPoint * p)
-{
-  gdouble min, min_max;
-  GSList * list = NULL, * i, * prev = NULL;
-
-  g_return_val_if_fail (tree != NULL, NULL);
-  g_return_val_if_fail (p != NULL, NULL);
-
-  gts_bbox_point_distance2 (tree->data, p, &min, &min_max);
-  min_max = bb_tree_min_max (tree, p, min_max, &list);
-
-  i = list;
-  while (i) {
-    GSList * next = i->next;
-    gdouble min, max;
-
-    gts_bbox_point_distance2 (i->data, p, &min, &max);
-
-    if (min > min_max) {
-      if (prev == NULL)
-	list = next;
-      else
-	prev->next = next;
-      g_slist_free_1 (i);
-    }
-    else
-      prev = i;
-    i = next;
-  }
-
-  return list;
-}
-
-/**
- * gts_bb_tree_point_distance:
- * @tree: a bounding box tree.
- * @p: a #GtsPoint.
- * @distance: a #GtsBBoxDistFunc.
- * @bbox: if not %NULL is set to the bounding box containing the closest 
- * object.
- *
- * Returns: the distance as evaluated by @distance between @p and the closest
- * object in @tree.
- */
-gdouble gts_bb_tree_point_distance (GNode * tree, 
-				    GtsPoint * p,
-				    GtsBBoxDistFunc distance,
-				    GtsBBox ** bbox)
-{
-  GSList * list, * i;
-  gdouble dmin = G_MAXDOUBLE;
-
-  g_return_val_if_fail (tree != NULL, dmin);
-  g_return_val_if_fail (p != NULL, dmin);
-  g_return_val_if_fail (distance != NULL, dmin);
-
-  i = list = gts_bb_tree_point_closest_bboxes (tree, p);
-  while (i) {
-    gdouble d = (*distance) (p, GTS_BBOX (i->data)->bounded);
-
-    if (fabs (d) < fabs (dmin)) {
-      dmin = d;
-      if (bbox)
-	*bbox = i->data;
-    }
-    i = i->next;
-  }
-  g_slist_free (list);
-
-  return dmin;
-}
-
-/**
- * gts_bb_tree_point_closest:
- * @tree: a bounding box tree.
- * @p: a #GtsPoint.
- * @closest: a #GtsBBoxClosestFunc.
- * @distance: if not %NULL is set to the distance between @p and the 
- * new #GtsPoint.
- *
- * Returns: a new #GtsPoint, closest point to @p and belonging to an object of
- * @tree.
- */
-GtsPoint * gts_bb_tree_point_closest (GNode * tree, 
-				      GtsPoint * p,
-				      GtsBBoxClosestFunc closest,
-				      gdouble * distance)
-{
-  GSList * list, * i;
-  gdouble dmin = G_MAXDOUBLE;
-  GtsPoint * np = NULL;
-
-  g_return_val_if_fail (tree != NULL, NULL);
-  g_return_val_if_fail (p != NULL, NULL);
-  g_return_val_if_fail (closest != NULL, NULL);
-
-  i = list = gts_bb_tree_point_closest_bboxes (tree, p);
-  while (i) {
-    GtsPoint * tp = (*closest) (p, GTS_BBOX (i->data)->bounded);
-    gdouble d = gts_point_distance2 (tp, p);
-
-    if (d < dmin) {
-      if (np)
-	gts_object_destroy (GTS_OBJECT (np));
-      np = tp;
-      dmin = d;
-    }
-    else
-      gts_object_destroy (GTS_OBJECT (tp));
-    i = i->next;
-  }
-  g_slist_free (list);
-
-  if (distance)
-    *distance = dmin;
-
-  return np;  
-}
-
-/**
- * gts_bb_tree_triangle_distance:
- * @tree: a bounding box tree.
- * @t: a #GtsTriangle.
- * @distance: a #GtsBBoxDistFunc.
- * @delta: spatial scale of the sampling to be used.
- * @range: a #GtsRange to be filled with the results.
- * 
- * Given a triangle @t, points are sampled regularly on its surface
- * using @delta as increment. The distance from each of these points
- * to the closest object of @tree is computed using @distance and the
- * gts_bb_tree_point_distance() function. The fields of @range are
- * filled with the number of points sampled, the minimum, average and
- * maximum value and the standard deviation.  
- */
-void gts_bb_tree_triangle_distance (GNode * tree,
-				    GtsTriangle * t,
-				    GtsBBoxDistFunc distance,
-				    gdouble delta,
-				    GtsRange * range)
-{
-  GtsPoint * p1, * p2, * p3, * p;
-  GtsVector p1p2, p1p3;
-  gdouble l1, t1, dt1;
-  guint i, n1;
-
-  g_return_if_fail (tree != NULL);
-  g_return_if_fail (t != NULL);
-  g_return_if_fail (distance != NULL);
-  g_return_if_fail (delta > 0.);
-  g_return_if_fail (range != NULL);
-
-  gts_triangle_vertices (t, 
-			 (GtsVertex **) &p1, 
-			 (GtsVertex **) &p2, 
-			 (GtsVertex **) &p3);
-
-  gts_vector_init (p1p2, p1, p2);
-  gts_vector_init (p1p3, p1, p3);
-  gts_range_init (range);
-  p = GTS_POINT (gts_object_new (GTS_OBJECT_CLASS (gts_point_class ())));
-
-  l1 = sqrt (gts_vector_scalar (p1p2, p1p2));
-  n1 = l1/delta + 1;
-  dt1 = 1.0/(gdouble) n1;
-  t1 = 0.0;
-  for (i = 0; i <= n1; i++, t1 += dt1) {
-    gdouble t2 = 1. - t1;
-    gdouble x = t2*p1p3[0];
-    gdouble y = t2*p1p3[1];
-    gdouble z = t2*p1p3[2];
-    gdouble l2 = sqrt (x*x + y*y + z*z);
-    guint j, n2 = (guint) (l2/delta + 1);
-    gdouble dt2 = t2/(gdouble) n2;
-
-    x = t2*p1->x + t1*p2->x;
-    y = t2*p1->y + t1*p2->y;
-    z = t2*p1->z + t1*p2->z;
-    
-    t2 = 0.0;
-    for (j = 0; j <= n2; j++, t2 += dt2) {
-      p->x = x + t2*p1p3[0];
-      p->y = y + t2*p1p3[1];
-      p->z = z + t2*p1p3[2];
-
-      gts_range_add_value (range,
-		    gts_bb_tree_point_distance (tree, p, distance, NULL));
-    }
-  }
-
-  gts_object_destroy (GTS_OBJECT (p));
-  gts_range_update (range);
-}
-
-/**
- * gts_bb_tree_segment_distance:
- * @tree: a bounding box tree.
- * @s: a #GtsSegment.
- * @distance: a #GtsBBoxDistFunc.
- * @delta: spatial scale of the sampling to be used.
- * @range: a #GtsRange to be filled with the results.
- * 
- * Given a segment @s, points are sampled regularly on its length
- * using @delta as increment. The distance from each of these points
- * to the closest object of @tree is computed using @distance and the
- * gts_bb_tree_point_distance() function. The fields of @range are
- * filled with the number of points sampled, the minimum, average and
- * maximum value and the standard deviation.  
- */
-void gts_bb_tree_segment_distance (GNode * tree,
-				   GtsSegment * s,
-				   gdouble (*distance) (GtsPoint *, 
-							gpointer),
-				   gdouble delta,
-				   GtsRange * range)
-{
-  GtsPoint * p1, * p2, * p;
-  GtsVector p1p2;
-  gdouble l, t, dt;
-  guint i, n;
-
-  g_return_if_fail (tree != NULL);
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (distance != NULL);
-  g_return_if_fail (delta > 0.);
-  g_return_if_fail (range != NULL);
-
-  p1 = GTS_POINT (s->v1);
-  p2 = GTS_POINT (s->v2);
-
-  gts_vector_init (p1p2, p1, p2);
-  gts_range_init (range);
-  p = GTS_POINT (gts_object_new (GTS_OBJECT_CLASS (gts_point_class())));
-
-  l = sqrt (gts_vector_scalar (p1p2, p1p2));
-  n = (guint) (l/delta + 1);
-  dt = 1.0/(gdouble) n;
-  t = 0.0;
-  for (i = 0; i <= n; i++, t += dt) {
-    p->x = p1->x + t*p1p2[0];
-    p->y = p1->y + t*p1p2[1];
-    p->z = p1->z + t*p1p2[2];
-    
-    gts_range_add_value (range,
-			 gts_bb_tree_point_distance (tree, p, distance, NULL));
-  }
-
-  gts_object_destroy (GTS_OBJECT (p));
-  gts_range_update (range);
-}
-
-static void surface_distance_foreach_triangle (GtsTriangle * t, 
-					       gpointer * data)
-{
-  gdouble * delta = data[1];
-  GtsRange * range = data[2];
-  gdouble * total_area = data[3], area;
-  GtsRange range_triangle;
-
-  gts_bb_tree_triangle_distance (data[0], t, data[4], *delta, &range_triangle);
-
-  if (range_triangle.min < range->min)
-    range->min = range_triangle.min;
-  if (range_triangle.max > range->max)
-    range->max = range_triangle.max;
-  range->n += range_triangle.n;
-
-  area = gts_triangle_area (t);
-  *total_area += area;
-  range->sum += area*range_triangle.mean;
-  range->sum2 += area*range_triangle.mean*range_triangle.mean;
-}
-
-/**
- * gts_bb_tree_surface_distance:
- * @tree: a bounding box tree.
- * @s: a #GtsSurface.
- * @distance: a #GtsBBoxDistFunc.
- * @delta: a sampling increment defined as the percentage of the diagonal
- * of the root bounding box of @tree.
- * @range: a #GtsRange to be filled with the results.
- *
- * Calls gts_bb_tree_triangle_distance() for each face of @s. The
- * fields of @range are filled with the minimum, maximum and average
- * distance. The average distance is defined as the sum of the average
- * distances for each triangle weighthed by their area and divided by
- * the total area of the surface. The standard deviation is defined
- * accordingly. The @n field of @range is filled with the number of
- * sampled points used.  
- */
-void gts_bb_tree_surface_distance (GNode * tree,
-				   GtsSurface * s,
-				   GtsBBoxDistFunc distance,
-				   gdouble delta,
-				   GtsRange * range)
-{
-  gpointer data[5];
-  gdouble total_area = 0.;
-
-  g_return_if_fail (tree != NULL);
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (delta > 0. && delta < 1.);
-  g_return_if_fail (range != NULL);
-
-  gts_range_init (range);
-  delta *= sqrt (gts_bbox_diagonal2 (tree->data));
-  data[0] = tree;
-  data[1] = &delta;
-  data[2] = range;
-  data[3] = &total_area;
-  data[4] = distance;
-
-  gts_surface_foreach_face (s, 
-			    (GtsFunc) surface_distance_foreach_triangle, 
-			    data);
-
-  if (total_area > 0.) {
-    if (range->sum2 - range->sum*range->sum/total_area >= 0.)
-      range->stddev = sqrt ((range->sum2 - range->sum*range->sum/total_area)
-			    /total_area);
-    else
-      range->stddev = 0.;
-    range->mean = range->sum/total_area;
-  }
-  else
-    range->min = range->max = range->mean = range->stddev = 0.;
-}
-
-static void surface_distance_foreach_boundary (GtsEdge * e,
-					       gpointer * data)
-{
-  gdouble * delta = data[1];
-  GtsRange * range = data[2];
-  gdouble * total_length = data[3], length;
-  GtsRange range_edge;
-
-  if (gts_edge_is_boundary (e, NULL)) {
-    GtsSegment * s =  GTS_SEGMENT (e);
-
-    gts_bb_tree_segment_distance (data[0], s, data[4], *delta, &range_edge);
-
-    if (range_edge.min < range->min)
-      range->min = range_edge.min;
-    if (range_edge.max > range->max)
-      range->max = range_edge.max;
-    range->n += range_edge.n;
-    
-    length = gts_point_distance (GTS_POINT (s->v1), GTS_POINT (s->v2));
-    *total_length += length;
-    range->sum += length*range_edge.mean;
-    range->sum2 += length*range_edge.mean*range_edge.mean;
-  }
-}
-
-/**
- * gts_bb_tree_surface_boundary_distance:
- * @tree: a bounding box tree.
- * @s: a #GtsSurface.
- * @distance: a #GtsBBoxDistFunc.
- * @delta: a sampling increment defined as the percentage of the diagonal
- * of the root bounding box of @tree.
- * @range: a #GtsRange to be filled with the results.
- *
- * Calls gts_bb_tree_segment_distance() for each edge boundary of @s.
- * The fields of @range are filled with the minimum, maximum and
- * average distance. The average distance is defined as the sum of the
- * average distances for each boundary edge weighthed by their length
- * and divided by the total length of the boundaries. The standard
- * deviation is defined accordingly. The @n field of @range is filled
- * with the number of sampled points used.  
- */
-void gts_bb_tree_surface_boundary_distance (GNode * tree,
-					    GtsSurface * s,
-					    gdouble (*distance) (GtsPoint *,
-								 gpointer),
-					    gdouble delta,
-					    GtsRange * range)
-{
-  gpointer data[5];
-  gdouble total_length = 0.;
-
-  g_return_if_fail (tree != NULL);
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (delta > 0. && delta < 1.);
-  g_return_if_fail (range != NULL);
-
-  gts_range_init (range);
-  delta *= sqrt (gts_bbox_diagonal2 (tree->data));
-  data[0] = tree;
-  data[1] = &delta;
-  data[2] = range;
-  data[3] = &total_length;
-  data[4] = distance;
-
-  gts_surface_foreach_edge (s, 
-			    (GtsFunc) surface_distance_foreach_boundary, 
-			    data);
-
-  if (total_length > 0.) {
-    if (range->sum2 - range->sum*range->sum/total_length >= 0.)
-      range->stddev = sqrt ((range->sum2 - 
-			     range->sum*range->sum/total_length)
-			    /total_length);
-    else
-      range->stddev = 0.;
-    range->mean = range->sum/total_length;
-  }
-  else
-    range->min = range->max = range->mean = range->stddev = 0.;
-}
diff --git a/src/gts/boolean.c b/src/gts/boolean.c
deleted file mode 100644
index 8b76d42..0000000
--- a/src/gts/boolean.c
+++ /dev/null
@@ -1,2048 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999--2002 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <math.h>
-#include "gts.h"
-
-/*#define DEBUG*/
-/*#define DEBUG_BOOLEAN*/
-/*#define CHECK_ORIENTED*/
-
-#ifdef DEBUG
-#  include "gts-private.h"
-#endif /* DEBUG */
-
-static void surface_inter_destroy (GtsObject * object)
-{
-  GtsSurfaceInter * si = GTS_SURFACE_INTER (object);
-
-  gts_object_destroy (GTS_OBJECT (si->s1));
-  gts_object_destroy (GTS_OBJECT (si->s2));
-  g_slist_free (si->edges);
-
-  (* GTS_OBJECT_CLASS (gts_surface_inter_class ())->parent_class->destroy)
-    (object);
-}
-
-static void surface_inter_class_init (GtsObjectClass * klass)
-{
-  klass->destroy = surface_inter_destroy;
-}
-
-static void surface_inter_init (GtsSurfaceInter * si)
-{
-  si->s1 = si->s2 = NULL;
-  si->edges = NULL;
-}
-
-/**
- * gts_surface_inter_class:
- *
- * Returns: the #GtsSurfaceInterClass.
- */
-GtsSurfaceInterClass * gts_surface_inter_class (void)
-{
-  static GtsSurfaceInterClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo surface_inter_info = {
-      "GtsSurfaceInter",
-      sizeof (GtsSurfaceInter),
-      sizeof (GtsSurfaceInterClass),
-      (GtsObjectClassInitFunc) surface_inter_class_init,
-      (GtsObjectInitFunc) surface_inter_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (gts_object_class (), &surface_inter_info);
-  }
-
-  return klass;
-}
-
-/* EdgeInter: Header */
-
-typedef struct _EdgeInter         EdgeInter;
-
-struct _EdgeInter {
-  GtsEdge parent;
-
-  GtsTriangle * t1, * t2;
-};
-
-#define EDGE_INTER(obj)            GTS_OBJECT_CAST (obj,\
-					         EdgeInter,\
-					         edge_inter_class ())
-#define IS_EDGE_INTER(obj)         (gts_object_is_from_class (obj,\
-						 edge_inter_class ()))
-
-static GtsEdgeClass * edge_inter_class  (void);
-static EdgeInter * edge_inter_new    (GtsVertex * v1, GtsVertex * v2,
-				      GtsTriangle * t1, GtsTriangle * t2);
-
-/* EdgeInter: Object */
-
-static GtsEdgeClass * edge_inter_class (void)
-{
-  static GtsEdgeClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo edge_inter_info = {
-      "EdgeInter",
-      sizeof (EdgeInter),
-      sizeof (GtsEdgeClass),
-      (GtsObjectClassInitFunc) NULL,
-      (GtsObjectInitFunc) NULL,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_constraint_class ()),
-				  &edge_inter_info);
-  }
-
-  return klass;
-}
-
-static EdgeInter * edge_inter_new (GtsVertex * v1, GtsVertex * v2,
-				   GtsTriangle * t1, GtsTriangle * t2)
-{
-  EdgeInter * object;
-
-  object = EDGE_INTER (gts_edge_new (GTS_EDGE_CLASS (edge_inter_class ()), 
-				     v1, v2));
-  object->t1 = t1;
-  object->t2 = t2;
-
-  return object;
-}
-
-#ifdef DEBUG
-static void write_surface_graph (GtsSurface * s, FILE * fp)
-{
-  GSList * l = NULL;
-  GtsGraph * g;
-  static void add_to_list (gpointer data, GSList ** l) {
-    *l = g_slist_prepend (*l, data);
-  }
-
-  gts_surface_foreach_vertex (s, (GtsFunc) gts_object_reset_reserved, NULL);
-  gts_surface_foreach_edge (s, (GtsFunc) gts_object_reset_reserved, NULL);
-  gts_surface_foreach_edge (s, (GtsFunc) add_to_list, &l);
-  g = gts_segments_graph_new (gts_graph_class (), l);
-  gts_graph_write_dot (g, fp);
-  gts_object_destroy (GTS_OBJECT (g));
-  g_slist_free (l);
-}
-#endif /* DEBUG */
-
-static GtsPoint * segment_triangle_intersection (GtsSegment * s,
-						 GtsTriangle * t,
-						 GtsPointClass * klass)
-{
-  GtsPoint * A, * B, * C, * D, * E;
-  gint ABCE, ABCD, ADCE, ABDE, BCDE;
-  GtsEdge * AB, * BC, * CA;
-  gdouble a, b, c;
-
-  g_return_val_if_fail (s != NULL, NULL);
-  g_return_val_if_fail (t != NULL, NULL);
-  g_return_val_if_fail (klass != NULL, NULL);
-
-  gts_triangle_vertices_edges (t, NULL, 
-			       (GtsVertex **) &A, 
-			       (GtsVertex **) &B, 
-			       (GtsVertex **) &C, 
-			       &AB, &BC, &CA);
-  D = GTS_POINT (s->v1);
-  E = GTS_POINT (s->v2);
-
-  ABCE = gts_point_orientation_3d_sos (A, B, C, E);
-  ABCD = gts_point_orientation_3d_sos (A, B, C, D);
-  if (ABCE < 0 || ABCD > 0) {
-    GtsPoint * tmpp;
-    gint tmp;
-
-    tmpp = E; E = D; D = tmpp;
-    tmp = ABCE; ABCE = ABCD; ABCD = tmp;
-  }
-  if (ABCE < 0 || ABCD > 0)
-    return NULL;
-  ADCE = gts_point_orientation_3d_sos (A, D, C, E);
-  if (ADCE < 0)
-    return NULL;
-  ABDE = gts_point_orientation_3d_sos (A, B, D, E);
-  if (ABDE < 0)
-    return NULL;
-  BCDE = gts_point_orientation_3d_sos (B, C, D, E);
-  if (BCDE < 0)
-    return NULL;
-  a = gts_point_orientation_3d (A, B, C, E);
-  b = gts_point_orientation_3d (A, B, C, D);
-  if (a != b) {
-    c = a/(a - b);
-    return gts_point_new (klass,
-			  E->x + c*(D->x - E->x),
-			  E->y + c*(D->y - E->y),
-			  E->z + c*(D->z - E->z));
-  }
-  /* D and E are contained within ABC */
-#ifdef DEBUG
-  fprintf (stderr, 
-	   "segment: %p:%s triangle: %p:%s intersection\n"
-	   "D and E contained in ABC\n",
-	   s, GTS_NEDGE (s)->name, t, GTS_NFACE (t)->name);
-#endif /* DEBUG */  
-  g_assert (a == 0.); 
-  return gts_point_new (klass,
-			(E->x + D->x)/2.,
-			(E->y + D->y)/2.,
-			(E->z + D->z)/2.);
-}
-
-static gint triangle_triangle_orientation (GtsPoint * p1, 
-					   GtsPoint * p2, GtsPoint * p3,
-					   GtsPoint * p4, GtsPoint * p5,
-					   GtsPoint * p6)
-{
-  gint o4 = 0, o5 = 0, o6 = 0;
-
-  if (p4 != p1 && p4 != p2 && p4 != p3)
-    o4 = gts_point_orientation_3d_sos (p1, p2, p3, p4);
-  if (p5 != p1 && p5 != p2 && p5 != p3)
-    o5 = gts_point_orientation_3d_sos (p1, p2, p3, p5);
-  if (o4*o5 < 0)
-    return 0;
-  if (p6 != p1 && p6 != p2 && p6 != p3)
-    o6 = gts_point_orientation_3d_sos (p1, p2, p3, p6);
-  if (o4*o6 < 0 || o5*o6 < 0)
-    return 0;
-  if (o4) return o4;
-  if (o5) return o5;
-  g_assert (o6);
-  return o6;
-}
-
-static gint triangle_point_orientation (GtsTriangle * t1, 
-					GtsTriangle * t2,
-					gint o1,
-					GtsPoint * p)
-{
-  GtsPoint * p1 = GTS_POINT (GTS_SEGMENT (t1->e1)->v1);
-  GtsPoint * p2 = GTS_POINT (GTS_SEGMENT (t1->e1)->v2);
-  GtsPoint * p3 = GTS_POINT (gts_triangle_vertex (t1));
-  GtsPoint * p4 = GTS_POINT (GTS_SEGMENT (t2->e1)->v1);
-  GtsPoint * p5 = GTS_POINT (GTS_SEGMENT (t2->e1)->v2);
-  GtsPoint * p6 = GTS_POINT (gts_triangle_vertex (t2));
-  gint o = triangle_triangle_orientation (p1, p2, p3, p4, p5, p6);
-
-  if (o != 0)
-    return o;
-  o = triangle_triangle_orientation (p4, p5, p6, p1, p2, p3);
-  if (o != 0) {
-    gint o2 = gts_point_orientation_3d_sos (p4, p5, p6, p);
-
-    return - o*o1*o2;
-  }
-  return 0;
-}
-
-static void add_edge_inter (GtsEdge * e,
-			    GtsTriangle * t,
-			    GtsVertex * v)
-{
-  GtsVertex * ev1 = GTS_SEGMENT (e)->v1, * ev2 = GTS_SEGMENT (e)->v2;
-  GList * i = GTS_OBJECT (e)->reserved;
-
-  GTS_OBJECT (v)->reserved = t;
-  if (i == NULL) {
-    GTS_OBJECT (e)->reserved = g_list_prepend (NULL, v);
-#ifdef DEBUG
-    fprintf (stderr, "add_edge_inter: inserting %p (%p,%p)\n", v, e, t);
-#endif /* DEBUG */
-  }
-  else {
-    GtsPoint * p1 = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
-    GtsPoint * p2 = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
-    GtsPoint * p3 = GTS_POINT (gts_triangle_vertex (t));
-    gint o1, oref = gts_point_orientation_3d_sos (p1, p2, p3, GTS_POINT (ev1));
-    
-    o1 = oref;
-    while (i) {
-      gint o2 = triangle_point_orientation (t, GTS_OBJECT (i->data)->reserved,
-					    oref, GTS_POINT (ev1));
-
-      if (o2 == 0) {
-#ifdef DEBUG
-	g_warning ("add_edge_inter: safe sign evaluation failed\n");
-#endif /* DEBUG */
-	o2 = gts_point_orientation_3d_sos (p1, p2, p3, i->data);
-      }
-
-      if (o1*o2 < 0)
-	break;
-      ev1 = i->data;
-      o1 = o2;
-      i = i->next;
-    }
-    if (i != NULL) {
-      GList * n = g_list_prepend (NULL, v);
-
-      ev2 = i->data;
-      n->next = i;
-      n->prev = i->prev;
-      i->prev = n;
-      if (n->prev == NULL)
-	GTS_OBJECT (e)->reserved = n;
-      else
-	n->prev->next = n;
-    }
-    else {
-      g_assert (o1*gts_point_orientation_3d_sos (p1, p2, p3, GTS_POINT (ev2))
-		< 0);
-      GTS_OBJECT (e)->reserved = g_list_append (GTS_OBJECT (e)->reserved, v);
-    }
-#ifdef DEBUG
-    fprintf (stderr, 
-	     "add_edge_inter: inserting %p (%p,%p) between %p and %p\n", 
-	     v, e, t, ev1, ev2);
-    i = GTS_OBJECT (e)->reserved;
-    while (i) {
-      fprintf (stderr, " %p", i->data);
-      i = i->next;
-    }
-    fprintf (stderr, "\n");
-#endif /* DEBUG */
-  }
-}
-
-static GtsVertex * intersects (GtsEdge * e,
-			       GtsTriangle * t,
-			       GtsSurface * s)
-{
-  GList * i = GTS_OBJECT (e)->reserved;
-  GtsVertex * v;
-
-  while (i) {
-    if (GTS_OBJECT (i->data)->reserved == t)
-      return i->data;
-    i = i->next;
-  }
-
-  v = GTS_VERTEX (segment_triangle_intersection (GTS_SEGMENT (e), t, 
-				    GTS_POINT_CLASS (s->vertex_class)));
-  if (v != NULL) {
-#ifdef DEBUG
-    if (GTS_IS_NVERTEX (v) && GTS_IS_NEDGE (e) && GTS_IS_NFACE (t) &&
-	GTS_NVERTEX (v)->name[0] == '\0')
-      g_snprintf (GTS_NVERTEX (v)->name, GTS_NAME_LENGTH, "%s|%s",
-		  GTS_NEDGE (e)->name, GTS_NFACE (t)->name);
-#endif /* DEBUG */
-    if (s->vertex_class->intersection_attributes)
-      (*s->vertex_class->intersection_attributes)
-	(v, GTS_OBJECT (e), GTS_OBJECT (t));
-    add_edge_inter (e, t, v);
-  }
-  return v;
-}
-
-/* see figure misc/orientation.fig */
-static gint intersection_orientation (GtsTriangle * t1, 
-				      GtsEdge * e,
-				      GtsTriangle * t2)
-{
-  GtsVertex * v1, * v2, * v3;
-  GtsEdge * e2, * e3;
-  GtsVertex * v4, * v5, * v6;
-
-  gts_triangle_vertices_edges (t1, e, &v1, &v2, &v3, &e, &e2, &e3);
-  gts_triangle_vertices (t2, &v4, &v5, &v6);
-
-  return gts_point_orientation_3d_sos (GTS_POINT (v4), 
-				       GTS_POINT (v5), 
-				       GTS_POINT (v6),
-				       GTS_POINT (v2));
-}
-
-#define UPDATE_ORIENTATION if (o > 0) { vi2 = v; e2 = e; } else { vi2 = vi1;\
-                                                                  e2 = e1;\
-                                                                  vi1 = v;\
-                                                                  e1 = e; }
-
-static void intersect_edges (GtsBBox * bb1, GtsBBox * bb2,
-			     GtsSurfaceInter * si)
-{
-  GtsSurface * s1 = GTS_OBJECT (si->s1)->reserved;
-  GtsTriangle * t1 = GTS_TRIANGLE (bb1->bounded);
-  GtsTriangle * t2 = GTS_TRIANGLE (bb2->bounded);
-  GtsVertex * v, * vi1 = NULL, * vi2 = NULL;
-  GtsEdge * e1 = NULL, * e2 = NULL, * e;
-
-  vi1 = intersects (t2->e1, t1, s1);
-  e1 = t2->e1;
-  v = intersects (t2->e2, t1, s1);
-  e = t2->e2;
-  if (!vi1) {
-    vi1 = v;
-    e1 = e;
-  }
-  else if (v) {
-    gint o = intersection_orientation (t2, t2->e2, t1);
-    UPDATE_ORIENTATION;
-  }
-  if (!vi2) {
-    v = intersects (t2->e3, t1, s1);
-    e = t2->e3;
-    if (!vi1) {
-      vi1 = v;
-      e1 = e;
-    }
-    else if (v) {
-      gint o = intersection_orientation (t2, t2->e3, t1);
-      UPDATE_ORIENTATION;
-    }
-  }
-  if (!vi2) {
-    v = intersects (t1->e1, t2, s1);
-    e = t1->e1;
-    if (!vi1) {
-      vi1 = v;
-      e1 = e;
-    }
-    else if (v) {
-      gint o = - intersection_orientation (t1, t1->e1, t2);
-      UPDATE_ORIENTATION;
-    }
-  }
-  if (!vi2) {
-    v = intersects (t1->e2, t2, s1);
-    e = t1->e2;
-    if (!vi1) {
-      vi1 = v;
-      e1 = e;
-    }
-    else if (v) {
-      gint o = - intersection_orientation (t1, t1->e2, t2);
-      UPDATE_ORIENTATION;
-    }
-  }
-  if (!vi2) {
-    v = intersects (t1->e3, t2, s1);
-    e = t1->e3;
-    if (!vi1) {
-      vi1 = v;
-      e1 = e;
-    }
-    else if (v) {
-      gint o = - intersection_orientation (t1, t1->e3, t2);
-      UPDATE_ORIENTATION;
-    }
-  }
-
-  g_assert ((!vi1 && !vi2) || (vi1 && vi2));
-  if (vi1) {
-    GtsEdge * e = GTS_EDGE (edge_inter_new (vi1, vi2, t1, t2));
-
-#ifdef DEBUG
-    fprintf (stderr, "creating constraint %p: %p->%p: %p/%p\n", 
-	     e, vi1, vi2, t1, t2);
-#endif /* DEBUG */
-    gts_surface_add_face (si->s1, GTS_FACE (t1));
-    gts_surface_add_face (si->s2, GTS_FACE (t2));
-    si->edges = g_slist_prepend (si->edges, e);
-    GTS_OBJECT (t1)->reserved = g_slist_prepend (GTS_OBJECT (t1)->reserved, e);
-    GTS_OBJECT (t2)->reserved = g_slist_prepend (GTS_OBJECT (t2)->reserved, e);
-  }
-}
-
-static GtsSurfaceInter * surface_inter_new (GtsSurfaceInterClass * klass,
-					    GtsSurface * s1,
-					    GtsSurface * s2,
-					    GNode * faces_tree1,
-					    GNode * faces_tree2)
-{
-  GtsSurfaceInter * si;
-
-  si = GTS_SURFACE_INTER (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  si->s1 = gts_surface_new (gts_surface_class (),
-			    s1->face_class,
-			    s1->edge_class,
-			    s1->vertex_class);
-  GTS_OBJECT (si->s1)->reserved = s1;
-  si->s2 = gts_surface_new (gts_surface_class (),
-			    s2->face_class,
-			    s2->edge_class,
-			    s2->vertex_class);
-  GTS_OBJECT (si->s2)->reserved = s2;
-  gts_bb_tree_traverse_overlapping (faces_tree1, faces_tree2,
-				    (GtsBBTreeTraverseFunc) intersect_edges, 
-				    si);
-
-  return si;
-}
-
-static void free_slist (GtsObject * o)
-{
-  g_slist_free (o->reserved);
-  o->reserved = NULL;
-}
-
-static void free_glist (GtsObject * o)
-{
-  g_list_foreach (o->reserved, (GFunc) gts_object_reset_reserved, NULL);
-  g_list_free (o->reserved);
-  o->reserved = NULL;
-}
-
-/**
- * gts_surface_intersection:
- * @s1: a #GtsSurface.
- * @s2: a #GtsSurface.
- * @faces_tree1: a bounding box tree (see gts_bb_tree_new()) for
- * the faces of @s1.
- * @faces_tree2: a bounding box tree for the faces of @s2.
- *
- * Returns: a list of #GtsEdge defining the curve intersection of the
- * two surfaces.
- */
-GSList * gts_surface_intersection (GtsSurface * s1,
-				   GtsSurface * s2,
-				   GNode * faces_tree1,
-				   GNode * faces_tree2)
-{
-  GtsSurfaceInter * si;
-  GSList * inter;
-
-  g_return_val_if_fail (s1 != NULL, NULL);
-  g_return_val_if_fail (s2 != NULL, NULL);
-  g_return_val_if_fail (faces_tree1 != NULL, NULL);
-  g_return_val_if_fail (faces_tree2 != NULL, NULL);
-
-  si = surface_inter_new (gts_surface_inter_class (),
-			  s1, s2, faces_tree1, faces_tree2);
-
-  gts_surface_foreach_face (si->s1, (GtsFunc) free_slist, NULL);
-  gts_surface_foreach_face (si->s2, (GtsFunc) free_slist, NULL);
-  gts_surface_foreach_edge (si->s1, (GtsFunc) free_glist, NULL);
-  gts_surface_foreach_edge (si->s2, (GtsFunc) free_glist, NULL);
-  inter = si->edges;
-  si->edges = NULL;
-  gts_object_destroy (GTS_OBJECT (si));
-
-  return inter;  
-}
-
-typedef enum {
-  INTERIOR = 1 << (GTS_USER_FLAG),
-  RELEVANT = 1 << (GTS_USER_FLAG + 1)
-} CurveFlag;
-
-#define IS_SET(s, f) ((GTS_OBJECT_FLAGS (s) & (f)) != 0)
-#define SET(s, f)   (GTS_OBJECT_FLAGS (s) |= (f))
-#define UNSET(s, f) (GTS_OBJECT_FLAGS (s) &= ~(f))
-#define NEXT(s)  (GTS_OBJECT (s)->reserved)
-
-#ifdef DEBUG
-static void print_segment (GtsSegment * s)
-{
-  fprintf (stderr, "%p: %s->%s ", s,
-	   GTS_NVERTEX (s->v1)->name,
-	   GTS_NVERTEX (s->v2)->name);
-  if (NEXT (s)) {
-    GtsSegment * next = NEXT (s);
-
-    fprintf (stderr, "next %p: %s->%s\n", next,
-	     GTS_NVERTEX (next->v1)->name,
-	     GTS_NVERTEX (next->v2)->name);
-  }
-  else
-    fprintf (stderr, "next NULL\n");
-}
-
-static void write_nodes (GSList * i, GHashTable * hash, guint * nn,
-			 FILE * fp)
-{
-  while (i) {
-    GtsSegment * s = i->data;
-
-    if (!g_hash_table_lookup (hash, s->v1)) {
-      fprintf (fp, "  %u [ label = \"%p\" ];\n", *nn, s->v1);
-      g_hash_table_insert (hash, s->v1, GUINT_TO_POINTER ((*nn)++));
-    }
-    if (!g_hash_table_lookup (hash, s->v2)) {
-      fprintf (fp, "  %u [ label = \"%p\" ];\n", *nn, s->v2);
-      g_hash_table_insert (hash, s->v2, GUINT_TO_POINTER ((*nn)++));
-    }
-    i = i->next;
-  }
-}
-
-static void write_edges (GSList * i, GHashTable * hash, 
-			 GtsSurface * surface,
-			 FILE * fp)
-{
-  while (i) {
-    GtsSegment * s = i->data;
-
-    fprintf (fp, "  %u -> %u [ label = \"%p:%d\" ];\n",
-	     GPOINTER_TO_UINT (g_hash_table_lookup (hash, s->v1)),
-	     GPOINTER_TO_UINT (g_hash_table_lookup (hash, s->v2)),
-	     s,
-	     gts_edge_face_number (GTS_EDGE (s), surface));
-    i = i->next;
-  }
-}
-
-static void write_graph (GSList * boundary, GSList * interior,
-			 GtsSurface * surface,
-			 FILE * fp)
-{
-  GHashTable * hash = g_hash_table_new (NULL, NULL);
-  guint nn = 1;
-  
-  fprintf (fp, "digraph oriented_curve {\n");
-  write_nodes (boundary, hash, &nn, fp);
-  write_nodes (interior, hash, &nn, fp);
-  write_edges (boundary, hash, surface, fp);
-  fprintf (fp, "  edge [ color = red ];\n");
-  write_edges (interior, hash, surface, fp);
-  fprintf (fp, "}\n");
-  g_hash_table_destroy (hash);
-}
-
-static void write_graph1 (GtsSegment * start, GSList * i,
-			  GtsSurface * surface,
-			  FILE * fp)
-{
-  GSList * boundary = NULL, * interior = NULL;
-  GtsSegment * s = start;
-
-  do {
-    boundary = g_slist_prepend (boundary, s);
-    s = NEXT (s);
-  } while (s != start);
-  while (i) {
-    if (IS_SET (i->data, INTERIOR))
-      interior = g_slist_prepend (interior, i->data);
-    i = i->next;
-  }
-  write_graph (boundary, interior, surface, fp);
-  g_slist_free (boundary);
-  g_slist_free (interior);
-}
-
-static void print_loop (GtsSegment * start, FILE * fp)
-{
-  GtsSegment * s = start;
-
-  do {
-    fprintf (fp, "  %p: %p:%s -> %p:%s\n",
-	     s, 
-	     s->v1, GTS_NVERTEX (s->v1)->name, 
-	     s->v2, GTS_NVERTEX (s->v2)->name);
-    s = NEXT (s);
-  } while (s != start && s != NULL);
-}
-
-static void draw_vector (GtsPoint * p1, GtsPoint * p2, FILE * fp)
-{
-  gdouble x = p2->x - p1->x;
-  gdouble y = p2->y - p1->y;
-  gdouble z = p2->z - p1->z;
-
-  fprintf (fp, "VECT 1 3 0 3 0 %g %g %g %g %g %g %g %g %g\n",
-	   p1->x + x - (x - y/2.)/5.,
-	   p1->y + y - (x/2. + y)/5.,
-	   p1->z + z - (x/2. + z)/5.,
-	   p1->x + x,
-	   p1->y + y,
-	   p1->z + z,
-	   p1->x + x - (x + y/2.)/5.,
-	   p1->y + y + (x/2. - y)/5.,
-	   p1->z + z + (x/2. - z)/5.);
-  fprintf (fp, "VECT 1 2 0 2 0 %g %g %g %g %g %g\n",
-	   p1->x, p1->y, p1->z,
-	   p1->x + x,
-	   p1->y + y,
-	   p1->z + z);
-}
-
-static void draw_vector1 (GtsPoint * p1, GtsPoint * p2, GtsPoint * o,
-			  FILE * fp)
-{
-  gdouble x1 = o->x + 0.9*(p1->x - o->x);
-  gdouble y1 = o->y + 0.9*(p1->y - o->y);
-  gdouble z1 = o->z + 0.9*(p1->z - o->z);
-  gdouble x2 = o->x + 0.9*(p2->x - o->x);
-  gdouble y2 = o->y + 0.9*(p2->y - o->y);
-  gdouble z2 = o->z + 0.9*(p2->z - o->z);
-  gdouble x = x2 - x1;
-  gdouble y = y2 - y1;
-  gdouble z = z2 - z1;
-
-  fprintf (fp, "VECT 1 3 0 3 0 %g %g %g %g %g %g %g %g %g\n",
-	   x1 + x - (x - y/2.)/5.,
-	   y1 + y - (x/2. + y)/5.,
-	   z1 + z - (x/2. + z)/5.,
-	   x1 + x,
-	   y1 + y,
-	   z1 + z,
-	   x1 + x - (x + y/2.)/5.,
-	   y1 + y + (x/2. - y)/5.,
-	   z1 + z + (x/2. - z)/5.);
-  fprintf (fp, "VECT 1 2 0 2 0 %g %g %g %g %g %g\n",
-	   x1, y1, z1,
-	   x1 + x,
-	   y1 + y,
-	   z1 + z);
-}
-
-static void write_segments (GSList * boundary, GSList * interior,
-			    FILE * fp)
-{
-  GSList * i = boundary;
-
-  fprintf (fp, "LIST {\n");
-  while (i) {
-    GSList * inext = i->next;
-    GtsSegment * s = i->data;
-    GtsSegment * next = inext ? inext->data : boundary->data;
-    GtsVertex * v1, * v2;
-
-    if (s->v1 != next->v1 && s->v1 != next->v2) {
-      v1 = s->v1;
-      v2 = s->v2;
-    }
-    else {
-      v1 = s->v2;
-      v2 = s->v1;
-    }
-    draw_vector (GTS_POINT (v1), GTS_POINT (v2), fp);
-    i = inext;
-  }
-  i = interior;
-  while (i) {
-    GtsSegment * s = i->data;
-
-    draw_vector (GTS_POINT (s->v1), GTS_POINT (s->v2), fp);
-    i = i->next;
-  }
-  fprintf (fp, "}\n");
-}
-
-static void write_loops (GSList * i, FILE * fp)
-{
-  guint nl = 0;
-
-  while (i) {
-    GtsSegment * start = i->data, * s;
-    GtsPoint os;
-    guint n = 0;
-
-    fprintf (fp, "(geometry \"loop%d\" = LIST {\n", nl++);    
-
-    os.x = os.y = os.z = 0.;
-    s = start;
-    do {
-      GtsSegment * next = NEXT (s);
-      GtsPoint * p;
-      
-      if (s->v1 != next->v1 && s->v1 != next->v2)
-	p = GTS_POINT (s->v1);
-       else
-	 p = GTS_POINT (s->v2);
-      os.x += p->x; os.y += p->y; os.z += p->z; n++;
-      s = next;
-     } while (s != start);
-    os.x /= n; os.y /= n; os.z /= n;
-    
-    s = start;
-    do {
-      GtsSegment * next = NEXT (s);
-      
-      if (s->v1 != next->v1 && s->v1 != next->v2)
-	draw_vector1 (GTS_POINT (s->v1), GTS_POINT (s->v2), &os, fp);
-      else
-	 draw_vector1 (GTS_POINT (s->v2), GTS_POINT (s->v1), &os, fp);
-      s = next;
-    } while (s != start);
-    
-    fprintf (fp, "})\n");
-
-    i = i->next;
-  }
-}
-
-#define NAME(v) (GTS_IS_NVERTEX (v) ? GTS_NVERTEX (v)->name : "")
-#endif /* DEBUG */
-
-static GtsSegment * prev_flag (GtsSegment * s, CurveFlag flag)
-{
-  GSList * i = s->v1->segments;
-
-  while (i) {
-    if (i->data != s && IS_SET (i->data, flag))
-      return i->data;
-    i = i->next;
-  }
-  return NULL;
-}
-
-static GtsSegment * next_flag (GtsSegment * s, CurveFlag flag)
-{
-  GSList * i = s->v2->segments;
-
-  while (i) {
-    if (i->data != s && IS_SET (i->data, flag))
-      return i->data;
-    i = i->next;
-  }
-  return NULL;
-}
-
-static GtsSegment * next_interior (GtsVertex * v)
-{
-  GSList * i = v->segments;
-
-  while (i) {
-    GtsSegment * s = i->data;
-
-    if (s->v1 == v && IS_SET (s, INTERIOR))
-      return s;
-    i = i->next;
-  }
-  return NULL;
-}
-
-static GtsSegment * prev_interior (GtsVertex * v)
-{
-  GSList * i = v->segments;
-
-  while (i) {
-    GtsSegment * s = i->data;
-
-    if (s->v2 == v && IS_SET (s, INTERIOR))
-      return s;
-    i = i->next;
-  }
-  return NULL;
-}
-
-static GtsSegment * reverse (GtsSegment * start,
-			     gboolean interior,
-			     gboolean * isloop)
-{
-  GtsSegment * s = start, * prev = NULL, * rprev = NULL;
-  GtsSegment * rstart = NULL, * rstart1 = NULL;
-
-  do {
-    GtsSegment * rs;
-
-    g_assert (IS_EDGE_INTER (s));
-    rs = GTS_SEGMENT (edge_inter_new (s->v2, s->v1,
-				      EDGE_INTER (s)->t1, EDGE_INTER (s)->t2));
-
-    if (rstart == NULL)
-      rstart = rs;
-    else if (rstart1 == NULL)
-      rstart1 = rs;
-    if (interior)
-      SET (rs, INTERIOR);
-    NEXT (rs) = rprev;
-    rprev = rs;
-    prev = s;
-    s = NEXT (s);
-  } while (s != NULL && s != start);
-  if (s == start) {
-    NEXT (rstart) = rprev;
-    *isloop = TRUE;
-  }
-  else {
-    NEXT (rstart) = start;
-    NEXT (prev) = rprev;
-    *isloop = FALSE;
-  }    
-  return rstart1;
-}
-
-static GSList * interior_loops (GSList * interior)
-{
-  GSList * i = interior;
-  GSList * loops = NULL;
-
-  i = interior;
-  while (i) {
-    GtsSegment * s = i->data;
-
-    if (IS_SET (s, RELEVANT)) {
-      GtsSegment * start = s, * end;
-
-      do {
-	GtsSegment * next = next_flag (s, INTERIOR);
-
-	UNSET (s, RELEVANT);
-	end = s; 
-	s = NEXT (s) = next;
-      } while (s != NULL && s != start);
-
-      if (s == start)
-	loops = g_slist_prepend (loops, start);
-      else {
-	GtsSegment * next, * prev;
-	gboolean isloop;
-
-	s = prev_flag (start, INTERIOR);
-	while (s) {
-	  UNSET (s, RELEVANT);
-	  NEXT (s) = start;
-	  start = s;
-	  s = prev_flag (s, INTERIOR);
-	}
-	next = next_flag (end, RELEVANT);
-	prev = prev_flag (start, RELEVANT);
-	if (prev != NULL)
-	  SET (start->v1, INTERIOR);
-	if (next != NULL)
-	  SET (end->v2, INTERIOR);
-	if (next == NULL && prev == NULL)
-	  loops = g_slist_prepend (loops, start);
-	else
-	  reverse (start, TRUE, &isloop);
-      }
-    }
-    i = i->next;
-  }
-  return loops;
-}
-
-#define ORIENTATION(p1,p2,p3,o) (gts_point_orientation_3d (p1, p2, o, p3))
-#define ORIENTATION_SOS(p1,p2,p3,o) (gts_point_orientation_3d_sos (p1, p2, o, p3))
-
-#define ORIENTED_VERTICES(s,next,w1,w2) {\
-  if ((s)->v1 == (next)->v1 || (s)->v1 == (next)->v2) {\
-    w1 = (s)->v2;\
-    w2 = (s)->v1;\
-  }\
-  else {\
-    w1 = (s)->v1;\
-    w2 = (s)->v2;\
-  }\
-}
-
-#if 0
-static GtsSegment * segment_intersects (GtsPoint * p1, GtsPoint * p2,
-					GSList * i,
-					GtsPoint * o)
-{
-  while (i) {
-    GtsSegment * s = i->data;
-    GtsPoint * p3 = GTS_POINT (s->v1);
-    GtsPoint * p4 = GTS_POINT (s->v2);
-
-    if (p3 != p1 && p3 != p2 && p4 != p1 && p4 != p2) {
-      gdouble o1 = ORIENTATION (p3, p4, p1, o);
-      gdouble o2 = ORIENTATION (p3, p4, p2, o);
-
-      if ((o1 < 0. && o2 > 0.) || (o1 > 0. && o2 < 0.)) {
-	o1 = ORIENTATION (p1, p2, p3, o);
-	o2 = ORIENTATION (p1, p2, p4, o);
-
-	if ((o1 <= 0. && o2 >= 0.) || (o1 >= 0. && o2 <= 0.))
-	  return s;
-      }
-    }
-    i = i->next;
-  }
-  return NULL;
-}
-#else
-static GtsSegment * segment_intersects (GtsPoint * p1, GtsPoint * p2,
-					GSList * i,
-					GtsPoint * o)
-{
-  while (i) {
-    GtsSegment * s = i->data;
-    GtsPoint * p3 = GTS_POINT (s->v1);
-    GtsPoint * p4 = GTS_POINT (s->v2);
-
-    if (p3 != p1 && p3 != p2 && p4 != p1 && p4 != p2) {
-      gint o1 = ORIENTATION_SOS (p3, p4, p1, o);
-      gint o2 = ORIENTATION_SOS (p3, p4, p2, o);
-
-      if (o1*o2 < 0) {
-	o1 = ORIENTATION_SOS (p1, p2, p3, o);
-	o2 = ORIENTATION_SOS (p1, p2, p4, o);
-
-	if (o1*o2 < 0)
-	  return s;
-      }
-    }
-    i = i->next;
-  }
-  return NULL;
-}
-#endif
-
-static gboolean is_inside_wedge (GtsSegment * s1, GtsSegment * s2,
-				 GtsPoint * p, GtsPoint * o)
-{
-  GtsVertex * v1, * v2, * v3;
-
-  ORIENTED_VERTICES (s1, s2, v1, v2);
-  v3 = s2->v1 != v2 ? s2->v1 : s2->v2;
-
-  if (ORIENTATION (GTS_POINT (v1), GTS_POINT (v2), 
-		   GTS_POINT (v3), o) >= 0.) {
-    if (ORIENTATION (GTS_POINT (v1), GTS_POINT (v2), p, o) <= 0. ||
-	ORIENTATION (GTS_POINT (v2), GTS_POINT (v3), p, o) <= 0.)
-      return FALSE;
-  }
-  else if (ORIENTATION (GTS_POINT (v1), GTS_POINT (v2), p, o) <= 0. &&
-	   ORIENTATION (GTS_POINT (v2), GTS_POINT (v3), p, o) <= 0.)
-    return FALSE;
-  return TRUE;
-}
-
-static GtsSegment * connection (GtsPoint * p, 
-				GSList * interior,
-				GSList * bloops,
-				GtsPoint * o)
-{
-  while (bloops) {
-    GtsSegment * start = bloops->data, * s = start;
-
-    do {
-      GtsSegment * next = NEXT (s);
-      GtsVertex * v2 = s->v1 == next->v1 || s->v1 == next->v2 ? s->v1 : s->v2;
-
-      if (is_inside_wedge (s, next, p, o) &&
-	  !segment_intersects (p, GTS_POINT (v2), interior, o))
-	return s;
-      s = next;
-    } while (s != start);
-    bloops = bloops->next;
-  }
-  return NULL;
-}
-
-static gdouble loop_orientation (GtsSegment * start,
-				 GtsPoint * p, GtsPoint * o)
-{
-  GtsSegment * s = start;
-  gdouble or = 0.;
-
-  do {
-    GtsSegment * next = NEXT (s);
-    GtsVertex * v1, * v2;
-
-    ORIENTED_VERTICES (s, next, v1, v2);
-    or += ORIENTATION (p, GTS_POINT (v1), GTS_POINT (v2), o);
-    s = next;
-  } while (s != start);
-
-#ifdef DEBUG
-  fprintf (stderr, "loop orientation: %g\n", or);
-#endif /* DEBUG */
-
-  return or;
-}
-
-static void connect_interior_loop (GtsSegment * start,
-				   GSList ** interior,
-				   GSList ** bloops,
-				   GtsSurface * surface,
-				   GtsPoint * o)
-{
-  GtsSegment * s = start, * c = NULL, * next, * s1, * rs1, * rs;
-  GtsVertex * v, * cv;
-  gboolean isloop;
-
-  do {
-    if (!(c = connection (GTS_POINT (s->v2), *interior, *bloops, o)))
-      s = NEXT (s);
-  } while (s != start && !c);
-  g_assert (c);
-  next = NEXT (c);
-  v = c->v1 == next->v1 || c->v1 == next->v2 ? c->v1 : c->v2;
-  cv = s->v2;
-#ifdef DEBUG
-  fprintf (stderr, "connecting %p:%s with %p:%s\n", 
-	   cv, NAME (cv), v, NAME (v));
-  fprintf (stderr, "  c: %p: %p:%s %p:%s\n", c, 
-	   c->v1, NAME (c->v1),
-	   c->v2, NAME (c->v2));
-  fprintf (stderr, "  next: %p: %p:%s %p:%s\n", next,
-	   next->v1, NAME (next->v1),
-	   next->v2, NAME (next->v2));
-#endif /* DEBUG */
-  rs = reverse (s, FALSE, &isloop);
-  if (isloop) {
-    if (loop_orientation (rs, GTS_POINT (v), o) < 0.) {
-      GtsSegment * tmp = s;
-      s = rs;
-      rs = tmp;
-    }
-    *bloops = g_slist_prepend (*bloops, rs);
-  }
-  s1 = GTS_SEGMENT (gts_edge_new (surface->edge_class, v, cv));
-  rs1 = GTS_SEGMENT (gts_edge_new (surface->edge_class, cv, v));
-  NEXT (c) = s1;
-  NEXT (rs1) = next;
-  *interior = g_slist_prepend (*interior, s1);
-  NEXT (s1) = NEXT (s);
-  NEXT (s) = rs1;
-}
-
-static GSList * boundary_loops (GSList * boundary)
-{
-  GSList * i = boundary;  
-  GtsSegment * start = i->data;
-  GSList * loops = NULL;
-
-  while (i) {
-    GtsSegment * s = i->data;
-    GSList * inext = i->next;
-    GtsSegment * next = inext ? inext->data : start;
-    GtsVertex * v = s->v1 == next->v1 || s->v1 == next->v2 ? s->v1 : s->v2;
-
-    if (IS_SET (v, INTERIOR)) {
-      GtsSegment * intprev = prev_interior (v);
-
-      NEXT (intprev) = next;
-      NEXT (s) = next_interior (v);
-      UNSET (v, INTERIOR);
-    }
-    else
-      NEXT (s) = next;
-    i = inext;
-  }
-
-  i = boundary;
-  while (i) {
-    start = i->data;
-    
-    if (IS_SET (start, RELEVANT)) {
-      GtsSegment * s = start;
-
-      do {
-	UNSET (s, RELEVANT);
-	UNSET (s, INTERIOR);
-	s = NEXT (s);
-      } while (s != start);
-      loops = g_slist_prepend (loops, start);
-    }
-    i = i->next;
-  }
-
-  return loops;
-}
-
-typedef struct _Ear    Ear;
-
-struct _Ear {
-  GtsVertex * v1, * v2, * v3;
-  GtsSegment * s1, * s2, * s3;
-};
-
-static gboolean point_in_wedge (GtsPoint * p1, GtsPoint * p2, GtsPoint * p3,
-				GtsPoint * p, gboolean closed, GtsPoint * o)
-{
-  gdouble o1;
-
-  if (p == p2 || p == p3)
-    return FALSE;
-  o1 = ORIENTATION (p1, p2, p, o);
-  if ((closed && o1 < 0.) || (!closed && o1 <= 0.)) return FALSE;
-  o1 = ORIENTATION (p3, p1, p, o);
-  if ((closed && o1 < 0.) || (!closed && o1 <= 0.)) return FALSE;
-  return TRUE;
-}
-
-#if 0
-static gboolean segment_intersects1 (GtsPoint * p1, GtsPoint * p2, 
-				     GtsPoint * p3, GtsPoint * p4,
-				     gboolean closed, GtsPoint * o)
-{
-  gdouble o1 = ORIENTATION (p3, p4, p1, o);
-  gdouble o2 = ORIENTATION (p3, p4, p2, o);
-  gdouble o3, o4;
-
-  if ((closed && ((o1 > 0. && o2 > 0.) || (o1 < 0. && o2 < 0.))) ||
-      (!closed && ((o1 >= 0. && o2 >= 0.) || (o1 <= 0. && o2 <= 0.))))
-    return FALSE;
-  o3 = ORIENTATION (p1, p2, p3, o);
-  o4 = ORIENTATION (p1, p2, p4, o);
-  if ((o3 > 0. && o4 > 0.) || (o3 < 0. && o4 < 0.))
-    return FALSE;
-  if (closed) return TRUE;
-  if ((o3 == 0. && o4 > 0.) || (o4 == 0. && o3 > 0.))
-    return TRUE;
-  return FALSE;
-}
-#else
-static gboolean segment_intersects1 (GtsPoint * p1, GtsPoint * p2, 
-				     GtsPoint * p3, GtsPoint * p4,
-				     gboolean closed, GtsPoint * o)
-{
-  gint o1, o2;
-
-  o1 = ORIENTATION_SOS (p3, p4, p1, o);
-  o2 = ORIENTATION_SOS (p3, p4, p2, o);
-  if (o1*o2 > 0)
-    return FALSE;
-  o1 = ORIENTATION_SOS (p1, p2, p3, o);
-  o2 = ORIENTATION_SOS (p1, p2, p4, o);
-  if (o1*o2 > 0)
-    return FALSE;
-  return TRUE;
-}
-#endif
-
-static GtsSegment * triangle_intersects_segments (GtsPoint * p1,
-						  GtsPoint * p2,
-						  GtsPoint * p3,
-						  gboolean closed,
-						  GtsSegment * start,
-						  GtsPoint * o)
-{
-  GtsSegment * s = start;
-
-  do {
-    GtsPoint * p4 = GTS_POINT (s->v1);
-    GtsPoint * p5 = GTS_POINT (s->v2);
-
-    if (p4 == p1) {
-      if (point_in_wedge (p1, p2, p3, p5, closed, o))
-	return s;
-    }
-    else if (p4 == p2) {
-      if (point_in_wedge (p2, p3, p1, p5, closed, o))
-	return s;
-    }
-    else if (p4 == p3) {
-      if (point_in_wedge (p3, p1, p2, p5, closed, o))
-	return s;
-    }
-    else if (p5 == p1) {
-      if (point_in_wedge (p1, p2, p3, p4, closed, o))
-	return s;
-    }
-    else if (p5 == p2) {
-      if (point_in_wedge (p2, p3, p1, p4, closed, o))
-	return s;
-    }
-    else if (p5 == p3) {
-      if (point_in_wedge (p3, p1, p2, p4, closed, o))
-	return s;
-    }
-    else if (segment_intersects1 (p1, p2, p4, p5, closed, o) ||
-	     segment_intersects1 (p2, p3, p4, p5, closed, o) ||
-	     segment_intersects1 (p3, p1, p4, p5, closed, o))
-      return s;
-    s = NEXT (s);
-  } while (s != start);
-  return NULL;
-}
-
-static gboolean new_ear (GtsSegment * s, 
-			 Ear * e, 
-			 GtsSegment * start,
-			 guint sloppy,
-			 GtsPoint * o)
-{
-  gdouble or;
-
-  e->s1 = s;
-  e->s2 = NEXT (s);
-
-  g_return_val_if_fail (e->s2, FALSE);
-  g_return_val_if_fail (e->s2 != e->s1, FALSE);
-
-  ORIENTED_VERTICES (e->s1, e->s2, e->v1, e->v2);
-  e->v3 = e->s2->v1 != e->v2 ? e->s2->v1 : e->s2->v2;
-  if (e->v3 == e->v1)
-    return FALSE;
-  e->s3 = NEXT (e->s2);
-  if (gts_segment_connect (e->s3, e->v1, e->v3)) {
-    if (NEXT (e->s3) != e->s1)
-      return FALSE;
-  }
-  else if (gts_vertices_are_connected (e->v1, e->v3))
-    return FALSE;
-  else
-    e->s3 = NULL;
-  or = ORIENTATION (GTS_POINT (e->v1), GTS_POINT (e->v2), GTS_POINT (e->v3),o);
-  switch (sloppy) {
-  case 0: 
-    if (or <= 0. ||
-	triangle_intersects_segments (GTS_POINT (e->v1), GTS_POINT (e->v2),
-				      GTS_POINT (e->v3), TRUE, start, o))
-      return FALSE;
-    break;
-  case 1:
-    if (or < 0. || 
-	(or > 0. && 
-	 triangle_intersects_segments (GTS_POINT (e->v1), GTS_POINT (e->v2),
-				       GTS_POINT (e->v3), FALSE, start, o)))
-      return FALSE;
-    break;
-  case 2:
-    if ((or > 0. && 
-	 triangle_intersects_segments (GTS_POINT (e->v1), GTS_POINT (e->v2),
-				       GTS_POINT (e->v3), FALSE, start, o)) ||
-	(or < 0. && 
-	 triangle_intersects_segments (GTS_POINT (e->v2), GTS_POINT (e->v1),
-				       GTS_POINT (e->v3), FALSE, start, o)))
-      return FALSE;
-    break;
-  case 3:
-    if (or < 0.)
-      return FALSE;
-    break;
-  }
-#ifdef DEBUG
-  if (or <= 0.)
-    fprintf (stderr, "or: %g\n", or);
-#endif /* DEBUG */
-  g_assert (or > -1e-6);
-  return TRUE;
-}
-
-static void triangulate_loop (GtsSegment * start,
-			      GtsSurface * surface,
-			      GtsPoint * o)
-{
-  GtsSegment * prev = start, * s;
-  guint sloppy = 0;
-#ifdef DEBUG
-  guint nt = 0;
-#endif /* DEBUG */
-
-  s = NEXT (start);
-  while (NEXT (s) != s) {
-    GtsSegment * next = NEXT (s);
-    Ear e;
-
-#ifdef DEBUG
-    fprintf (stderr, "prev: %p s: %p next: %p\n", prev, s, next);
-#endif /* DEBUG */
-  
-    if (!new_ear (s, &e, start, sloppy, o)) {
-      if (s == start) {
-	sloppy++;
-#ifdef DEBUG
-	fprintf (stderr, "sloppy: %u\n", sloppy);
-#endif /* DEBUG */
-      }
-      prev = s;
-      s = next;
-    }
-    else {
-      GtsFace * f;
-
-      if (!GTS_IS_EDGE (e.s3))
-	e.s3 = GTS_SEGMENT (gts_edge_new (surface->edge_class, e.v1, e.v3));
-      f = gts_face_new (surface->face_class, 
-			GTS_EDGE (e.s1), GTS_EDGE (e.s2), GTS_EDGE (e.s3));
-      gts_surface_add_face (surface, f);
-      UNSET (e.s1, RELEVANT);
-      UNSET (e.s1, INTERIOR);
-      UNSET (e.s2, RELEVANT);
-      UNSET (e.s2, INTERIOR);
-      NEXT (prev) = e.s3;
-      NEXT (e.s3) = NEXT (e.s2);
-      NEXT (e.s1) = NEXT (e.s2) = NULL;
-      start = prev;
-      s = NEXT (prev);
-      sloppy = 0;
-#ifdef DEBUG
-      {
-	gchar name[80];
-	FILE * fp;
-	
-	fprintf (stderr, " t.%u: (%p:%s,%p:%s,%p:%s)\n",
-		 nt, 
-		 e.v1, NAME (e.v1),
-		 e.v2, NAME (e.v2),
-		 e.v3, NAME (e.v3));
-	sprintf (name, "/tmp/t.%u", nt++);
-	fp = fopen (name, "wt");
-	//	gts_surface_write (surface, fp);
-	gts_write_triangle (GTS_TRIANGLE (f), NULL, fp);
-	//	  write_graph1 (start, interior, surface, fp);
-	fclose (fp);
-	print_loop (start, stderr);
-      }
-#endif /* DEBUG */
-    }
-  }
-  UNSET (s, RELEVANT);
-  UNSET (s, INTERIOR);
-  NEXT (s) = NULL;
-}
-
-#ifdef CHECK_ORIENTED
-static void check_object (GtsObject * o)
-{
-  g_assert (o->reserved == NULL);
-  g_assert (o->flags == 0);  
-}
-
-static void check_boundary (GtsEdge * e, GtsSurface * s)
-{
-  check_object (GTS_OBJECT (e));
-  check_object (GTS_OBJECT (GTS_SEGMENT (e)->v1));
-  check_object (GTS_OBJECT (GTS_SEGMENT (e)->v2));
-  g_assert (gts_edge_face_number (e, s) == 1);
-}
-
-static void check_interior (GtsEdge * e, GtsSurface * s)
-{
-  guint n;
-  check_object (GTS_OBJECT (e));
-  check_object (GTS_OBJECT (GTS_SEGMENT (e)->v1));
-  check_object (GTS_OBJECT (GTS_SEGMENT (e)->v2));
-
-  n = gts_edge_face_number (e, s);
-#ifdef DEBUG
-  if (n != 2)
-    gts_surface_print_stats (s, stderr);
-#endif /* DEBUG */
-  g_assert (n == 2);
-}
-
-static void check_boundary_interior_triangulation (GSList * boundary,
-						   GSList * interior,
-						   GtsSurface * surface)
-{
-  g_slist_foreach (boundary, (GFunc) check_boundary, surface);
-  g_slist_foreach (interior, (GFunc) check_interior, surface);
-}
-#endif /*ifdef CHECK_ORIENTED */
-
-static void merge_duplicate (GtsEdge * e)
-{
-  GtsEdge * dup = gts_edge_is_duplicate (e);
-
-  g_assert (dup);
-  gts_edge_replace (dup, e);
-  gts_object_destroy (GTS_OBJECT (dup));
-}
-
-static void triangulate_boundary_interior (GSList * boundary, 
-					   GSList * interior,
-					   GtsSurface * s,
-					   GtsPoint * o)
-{
-  GSList * iloops, * bloops, * i;
-
-  i = boundary;
-  while (i) {
-    SET (i->data, RELEVANT);
-    i = i->next;
-  }
-  i = interior;
-  while (i) {
-    SET (i->data, RELEVANT);
-    SET (i->data, INTERIOR);
-    i = i->next;
-  }
-
-  iloops = interior_loops (interior);
-  bloops = boundary_loops (boundary);
-
-  i = iloops;
-  while (i) {
-#ifdef DEBUG
-    fprintf (stderr, "--- interior loop ---\n");
-    print_loop (i->data, stderr);
-#endif /* DEBUG */
-    connect_interior_loop (i->data, &interior, &bloops, s, o);
-    i = i->next;
-  }
-  
-#ifdef DEBUG
- {
-   FILE * fp = fopen ("/tmp/bloops", "w");
-   write_loops (bloops, fp);
-   fclose (fp);
- }
-#endif /* DEBUG */
-
-  i = bloops;
-  while (i) {
-#ifdef DEBUG
-    fprintf (stderr, "--- boundary loop ---\n");
-    print_loop (i->data, stderr);
-#endif /* DEBUG */
-    triangulate_loop (i->data, s, o);
-    i = i->next;
-  }
-  
-  g_slist_foreach (interior, (GFunc) merge_duplicate, NULL);
-  g_slist_free (iloops);
-  g_slist_free (bloops);
-
-#ifdef CHECK_ORIENTED
-  check_boundary_interior_triangulation (boundary, interior, s);
-#endif /* CHECK_ORIENTED */
-}
-
-static void create_edges (GtsSegment * s, GtsSurface * surface)
-{
-  if (GTS_OBJECT (s)->reserved) {
-    GList * i = GTS_OBJECT (s)->reserved;
-    GtsVertex * v1 = i->data;
-
-    GTS_OBJECT (s)->reserved = g_list_prepend (i, 
-		      gts_edge_new (surface->edge_class, s->v1, v1));
-    while (i) {
-      GList * next = i->next;
-      GtsVertex * v2 = next ? next->data : s->v2;
-
-      GTS_OBJECT (i->data)->reserved = NULL;
-      i->data = gts_edge_new (surface->edge_class, v1, v2);
-      v1 = v2;
-      i = next;
-    }
-  }
-}
-
-static void add_boundary (GtsSegment * s, GtsSegment * next, 
-			  GSList ** boundary)
-{
-  if (GTS_OBJECT (s)->reserved == NULL)
-    *boundary = g_slist_prepend (*boundary, s);
-  else {
-    if (s->v2 == next->v2 || s->v2 == next->v1) {
-      GList * i = g_list_last (GTS_OBJECT (s)->reserved);
-
-      while (i) {
-	*boundary = g_slist_prepend (*boundary, i->data);
-	i = i->prev;
-      }
-    }
-    else {
-      GList * i = GTS_OBJECT (s)->reserved;
-
-      while (i) {
-	*boundary = g_slist_prepend (*boundary, i->data);
-	i = i->next;
-      }
-    }
-  }
-}
-
-static void triangulate_face (GtsTriangle * t, GtsSurface * surface)
-{
-  GSList * interior = GTS_OBJECT (t)->reserved;
-  GSList * boundary = NULL;
-  GtsSurface * s = gts_surface_new (gts_surface_class (),
-				    surface->face_class,
-				    surface->edge_class,
-				    surface->vertex_class);
-  gdouble x, y, z;
-  GtsPoint * p = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
-  GtsPoint * o;
-
-  GTS_OBJECT (t)->reserved = NULL;  
-  gts_triangle_normal (t, &x, &y, &z);
-  g_assert (x != 0. || y != 0. || z != 0.);
-  o = gts_point_new (gts_point_class (), p->x + x, p->y + y, p->z + z);
-  add_boundary (GTS_SEGMENT (t->e3), GTS_SEGMENT (t->e1), &boundary);
-  add_boundary (GTS_SEGMENT (t->e2), GTS_SEGMENT (t->e3), &boundary);
-  add_boundary (GTS_SEGMENT (t->e1), GTS_SEGMENT (t->e2), &boundary);
-#ifdef DEBUG
-  {
-    static guint nt = 0;
-    char name[80];
-    FILE * fp;
-
-    fprintf (stderr, "%u: triangulating %p\n", nt, t);
-if (nt == 28)
-  fprintf (stderr, "tintin!!!!\n");
-    sprintf (name, "/tmp/oc.%u", nt++);
-    fp = fopen (name, "wt");
-    //    write_graph (boundary, interior, s, fp);
-    write_segments (boundary, interior, fp);
-    fclose (fp);
-  }
-#endif /* DEBUG */
-  triangulate_boundary_interior (boundary, interior, s, o);
-  g_slist_free (interior);
-  g_slist_free (boundary);
-  if (GTS_OBJECT (t)->klass->attributes)
-    gts_surface_foreach_face (s, (GtsFunc) gts_object_attributes, t);
-  gts_surface_merge (surface, s);
-  gts_object_destroy (GTS_OBJECT (s));
-  gts_object_destroy (GTS_OBJECT (o));
-}
-
-static void free_edge_list (GtsObject * o)
-{
-  g_list_free (o->reserved);
-  o->reserved = NULL;
-}
-
-/**
- * gts_surface_inter_new:
- * @klass: a #GtsSurfaceInterClass.
- * @s1: a #GtsSurface.
- * @s2: a #GtsSurface.
- * @faces_tree1: a bounding box tree (see gts_bb_tree_new()) for
- * the faces of @s1.
- * @faces_tree2: a bounding box tree for the faces of @s2.
- * @is_open1: whether @s1 is an "open" surface.
- * @is_open2: whether @s2 is an "open" surface.
- *
- * When triangulating the cut faces, the new faces inherit the
- * attributes of these original faces through their attributes()
- * method.
- *
- * Returns: a new #GtsSurfaceInter describing the intersection of @s1
- * and @s2.  
- */
-GtsSurfaceInter * gts_surface_inter_new (GtsSurfaceInterClass * klass,
-					 GtsSurface * s1,
-					 GtsSurface * s2,
-					 GNode * faces_tree1,
-					 GNode * faces_tree2,
-					 gboolean is_open1,
-					 gboolean is_open2)
-{
-  GtsSurfaceInter * si;
-  GtsSurface * s;
-
-  g_return_val_if_fail (klass != NULL, NULL);
-  g_return_val_if_fail (s1 != NULL, NULL);
-  g_return_val_if_fail (s2 != NULL, NULL);
-  g_return_val_if_fail (faces_tree1 != NULL, NULL);
-  g_return_val_if_fail (faces_tree2 != NULL, NULL);
-
-  si = surface_inter_new (klass, s1, s2, faces_tree1, faces_tree2);
-
-  gts_surface_foreach_edge (si->s1, (GtsFunc) create_edges, si->s1);
-  gts_surface_foreach_edge (si->s2, (GtsFunc) create_edges, si->s2);
-
-#ifdef DEBUG
-  fprintf (stderr, "====== triangulating s1 ======\n");
-#endif /* DEBUG */
-  s = gts_surface_new (gts_surface_class (),
-		       s1->face_class,
-		       s1->edge_class,
-		       s1->vertex_class);
-  gts_surface_foreach_face (si->s1, (GtsFunc) triangulate_face, s);
-  gts_surface_foreach_edge (si->s1, (GtsFunc) free_edge_list, NULL);
-  gts_object_destroy (GTS_OBJECT (si->s1));
-  si->s1 = s;
-  GTS_OBJECT (si->s1)->reserved = s1;
-  
-#ifdef DEBUG
-  fprintf (stderr, "====== triangulating s2 ======\n");
-#endif /* DEBUG */
-  s = gts_surface_new (gts_surface_class (),
-		       s2->face_class,
-		       s2->edge_class,
-		       s2->vertex_class);
-  gts_surface_foreach_face (si->s2, (GtsFunc) triangulate_face, s);
-  gts_surface_foreach_edge (si->s2, (GtsFunc) free_edge_list, NULL);
-  gts_object_destroy (GTS_OBJECT (si->s2));
-  si->s2 = s;
-  GTS_OBJECT (si->s2)->reserved = s2;
-
-  return si;
-}
-
-static void check_surface_edge (GtsEdge * e, gpointer * data)
-{
-  gboolean * ok = data[0];
-  GtsSurface * s = data[1];
-  GtsSurface * bs = GTS_OBJECT (s)->reserved;
-  guint nf = gts_edge_face_number (e, s);
-
-  if (nf < 1 || nf > 2) {
-    *ok = FALSE;
-    g_return_if_fail (nf >= 1 && nf <= 2);
-  }
-  if (nf == 1 && gts_edge_face_number (e, bs) == 0) {
-    *ok = FALSE;
-    g_return_if_fail (gts_edge_face_number (e, bs) > 0);
-  }
-}
-
-static void mark_edge (GtsObject * o, gpointer data)
-{
-  o->reserved = data;
-}
-
-static gint triangle_orientation (GtsTriangle * t, GtsEdge * e)
-{
-  GtsSegment * s = GTS_SEGMENT (t->e1 == e ? t->e2 
-				: 
-				t->e2 == e ? t->e3 
-				: 
-				t->e1);
-  GtsVertex * v2 = GTS_SEGMENT (e)->v2;
-
-  if (s->v1 == v2 || s->v2 == v2)
-    return 1;
-  return -1;
-}
-
-static gboolean check_orientation (GtsEdge * e, GtsSurface * s)
-{
-  GtsTriangle * t1 = NULL, * t2 = NULL;
-  GSList * i = e->triangles;
-  gint o1 = 0, o2 = 0;
-
-  while (i) {
-    if (GTS_IS_FACE (i->data) && 
-	gts_face_has_parent_surface (i->data, s)) {
-      if (t1 == NULL) {
-	t1 = i->data;
-	o1 = triangle_orientation (t1, e);
-      }
-      else if (t2 == NULL) {
-	t2 = i->data;
-	o2 = triangle_orientation (t2, e);
-	g_return_val_if_fail (o1*o2 < 0, FALSE);
-      }
-      else
-	g_assert_not_reached ();
-    }
-    i = i->next;
-  }
-  g_return_val_if_fail (t1 && t2, FALSE);
-  return TRUE;
-}
-
-static void check_edge (GtsSegment * s, gpointer * data)
-{
-  gboolean * ok = data[0];
-  GtsSurfaceInter * si = data[1];
-  gboolean * closed = data[2];
-  GSList * j;
-  guint nn = 0;
-  
-  j = s->v1->segments;
-  while (j && *ok) {
-    GtsSegment * s1 = j->data;
-    
-    if (s1 != s && GTS_OBJECT (s1)->reserved == si) {
-      if (s1->v2 != s->v1)
-	*ok = FALSE;
-      nn++;
-    }
-    j = j->next;
-  }
-  j = s->v2->segments;
-  while (j && *ok) {
-    GtsSegment * s1 = j->data;
-    
-    if (s1 != s && GTS_OBJECT (s1)->reserved == si) {
-      if (s1->v1 != s->v2)
-	*ok = FALSE;
-      nn++;
-    }
-    j = j->next;
-  }
-  if (nn != 2)
-    *closed = FALSE;
-
-  if (!check_orientation (GTS_EDGE (s), si->s1))
-    *ok = FALSE;
-  if (!check_orientation (GTS_EDGE (s), si->s2))
-    *ok = FALSE;
-}
-
-/**
- * gts_surface_inter_check:
- * @si: a #GtsSurfaceInter.
- * @closed: is set to %TRUE if @si->edges is a closed curve, %FALSE
- * otherwise.
- *
- * Returns: %TRUE if the curve described by @si is an orientable
- * manifold, %FALSE otherwise.  
- */
-gboolean gts_surface_inter_check (GtsSurfaceInter * si,
-				  gboolean * closed)
-{
-  gboolean ok = TRUE;
-  gpointer data[3];
-
-  g_return_val_if_fail (si != NULL, FALSE);
-  g_return_val_if_fail (closed != NULL, FALSE);
-
-  *closed = si->edges ? TRUE : FALSE;
-
-  /* mark edges as used by si */
-  g_slist_foreach (si->edges, (GFunc) mark_edge, si);
-
-  data[0] = &ok;
-  data[1] = si;
-  data[2] = closed;
-  g_slist_foreach (si->edges, (GFunc) check_edge, data);
-  g_slist_foreach (si->edges, (GFunc) gts_object_reset_reserved, NULL);
-
-  /* check connectivity of the faces of @si */
-  if (*closed) {
-    gpointer data[2];
-
-    data[0] = &ok;
-    data[1] = si->s1;
-    gts_surface_foreach_edge (si->s1, (GtsFunc) check_surface_edge, data);
-    data[1] = si->s2;
-    gts_surface_foreach_edge (si->s2, (GtsFunc) check_surface_edge, data);
-  }
-
-  return ok;
-}
-
-/* Given @e and @f returns a #GtsFace compatible with @f and belonging to
-   @s1 or @s2 */
-static GtsFace * next_compatible_face (GtsEdge * e, 
-				       GtsFace * f, 
-				       GtsSurface * s1,
-				       GtsSurface * s2)
-{
-  GSList * i = e->triangles;
-  GtsFace * f2 = NULL, * f3 = NULL;
-
-  while (i) {
-    GtsFace * f1 = i->data;
-
-    if (f1 != f && GTS_IS_FACE (f1)) {
-      if (gts_face_has_parent_surface (f1, s1))
-	return f1;
-      if (gts_face_has_parent_surface (f1, s2)) {
-	if (f2 == NULL) f2 = f1;
-	else if (f3 == NULL) f3 = f1;
-	else g_assert_not_reached (); /* s2 is a non-manifold surface */
-      }
-    }
-    i = i->next;
-  }
-  if (f3 == NULL) {
-    if (gts_edge_is_boundary (e, s2))
-      return NULL;
-    return f2; 
-  }
-  g_assert (gts_face_has_parent_surface (f, s1));
-  if (gts_triangles_are_compatible (GTS_TRIANGLE (f), GTS_TRIANGLE (f2), e))
-    return f2;
-  return f3;
-}
-
-static void walk_faces (GtsEdge * e, GtsFace * f, 
-			GtsSurface * s1,
-			GtsSurface * s2,
-			GtsSurface * s)
-{
-  GtsFifo * faces = gts_fifo_new ();
-  GtsFifo * edges = gts_fifo_new ();
-
-  gts_fifo_push (faces, f);
-  gts_fifo_push (edges, e);
-  while ((f = gts_fifo_pop (faces)) && (e = gts_fifo_pop (edges))) {
-    if (!GTS_OBJECT (f)->reserved) {
-      GtsTriangle * t = GTS_TRIANGLE (f);
-      GtsFace * f1;
-
-      gts_surface_add_face (s, f);
-      GTS_OBJECT (f)->reserved = s;
-      if (t->e1 != e && !GTS_OBJECT (t->e1)->reserved &&
-	  (f1 = next_compatible_face (t->e1, f, s1, s2))) {
-	gts_fifo_push (faces, f1);
-	gts_fifo_push (edges, t->e1);
-      }	
-      if (t->e2 != e && !GTS_OBJECT (t->e2)->reserved &&
-	  (f1 = next_compatible_face (t->e2, f, s1, s2))) {
-	gts_fifo_push (faces, f1);
-	gts_fifo_push (edges, t->e2);
-      }	
-      if (t->e3 != e && !GTS_OBJECT (t->e3)->reserved &&
-	  (f1 = next_compatible_face (t->e3, f, s1, s2))) {
-	gts_fifo_push (faces, f1);
-	gts_fifo_push (edges, t->e3);
-      }	
-    }
-  }
-  gts_fifo_destroy (faces);
-  gts_fifo_destroy (edges);
-}
-
-/**
- * gts_surface_inter_boolean:
- * @si: a #GtsSurfaceInter.
- * @surface: a #GtsSurface.
- * @op: a #GtsBooleanOperation.
- *
- * Adds to @surface the part of the surface described by @si and @op.
- */
-void gts_surface_inter_boolean (GtsSurfaceInter * si,
-				GtsSurface * surface,
-				GtsBooleanOperation op)
-{
-  GtsSurface * s = NULL;
-  gint orient = 1;
-  GSList * i;
-
-  g_return_if_fail (si != NULL);
-  g_return_if_fail (surface != NULL);
-
-  switch (op) {
-  case GTS_1_OUT_2: s = si->s1; orient = 1; break;
-  case GTS_1_IN_2: s = si->s1; orient = -1; break;
-  case GTS_2_OUT_1: s = si->s2; orient = -1; break;
-  case GTS_2_IN_1: s = si->s2; orient = 1; break;
-  default: g_assert_not_reached ();
-  }
-
-  /* mark edges as belonging to intersection */
-  g_slist_foreach (si->edges, (GFunc) mark_edge, si);
-
-  i = si->edges;
-  while (i) {
-    GtsEdge * e = i->data;
-    GSList * j = e->triangles;
-    
-    while (j) {
-      if (gts_face_has_parent_surface (j->data, s) &&
-	  orient*triangle_orientation (j->data, e) > 0) {
-#ifdef DEBUG_BOOLEAN
-	GtsFace * boundary = gts_edge_is_boundary (e, surface);
-
-	g_assert (!boundary || boundary == j->data);
-#endif /* DEBUG_BOOLEAN */
-	walk_faces (e, j->data, s, GTS_OBJECT (s)->reserved, surface);
-	break;
-      }
-      j = j->next;
-    }
-    i = i->next;
-  }
-  g_slist_foreach (si->edges, (GFunc) gts_object_reset_reserved, NULL);
-  gts_surface_foreach_face (surface, 
-			    (GtsFunc) gts_object_reset_reserved, NULL);
-}
-
-static void self_intersecting (GtsBBox * bb1, GtsBBox * bb2, 
-			       gpointer * d)
-{
-  GtsTriangle * t1 = bb1->bounded;
-  GtsTriangle * t2 = bb2->bounded;
-
-  if (t1 != t2) {
-    GtsSegment * s1 = GTS_SEGMENT (t1->e1);
-    GtsSegment * s2 = GTS_SEGMENT (t1->e2);
-    GtsSegment * s3 = GTS_SEGMENT (t1->e3);
-    GtsSegment * s4 = GTS_SEGMENT (t2->e1);
-    GtsSegment * s5 = GTS_SEGMENT (t2->e2);
-    GtsSegment * s6 = GTS_SEGMENT (t2->e3);
-    GtsPoint * pi;
-
-    if ((!gts_segments_touch (s4, s1) && 
-	 !gts_segments_touch (s4, s2) &&
-	 !gts_segments_touch (s4, s3) &&
-	 (pi = segment_triangle_intersection (s4, t1, gts_point_class ()))
-	 != NULL) ||
-	(!gts_segments_touch (s5, s1) && 
-	 !gts_segments_touch (s5, s2) &&
-	 !gts_segments_touch (s5, s3) &&
-	 (pi = segment_triangle_intersection (s5, t1, gts_point_class ())) 
-	 != NULL) ||
-	(!gts_segments_touch (s6, s1) && 
-	 !gts_segments_touch (s6, s2) &&
-	 !gts_segments_touch (s6, s3) &&
-	 (pi = segment_triangle_intersection (s6, t1, gts_point_class ())) 
-	 != NULL)) {
-      GtsBBTreeTraverseFunc func = d[0];
-      gpointer data = d[1];
-      gboolean * self_inter = d[2];
-
-      gts_object_destroy (GTS_OBJECT (pi));
-      *self_inter = TRUE;
-      (* func) (bb1, bb2, data);
-    }
-  }
-}
-
-/**
- * gts_surface_foreach_intersecting_face:
- * @s: a #GtsSurface.
- * @func: a #GtsBBTreeTraverseFunc.
- * @data: user data to pass to @func.
- *
- * Calls @func for each intersecting pair of faces of @s.
- *
- * Returns: %TRUE if @func was called at least once, %FALSE otherwise.
- */
-gboolean gts_surface_foreach_intersecting_face (GtsSurface * s,
-						GtsBBTreeTraverseFunc func,
-						gpointer data)
-{
-  GNode * tree;
-  gpointer d[3];
-  gboolean self_inter = FALSE;
-
-  g_return_val_if_fail (s != NULL, FALSE);
-  g_return_val_if_fail (func != NULL, FALSE);
-
-  tree = gts_bb_tree_surface (s);
-  d[0] = func;
-  d[1] = data;
-  d[2] = &self_inter;
-  gts_bb_tree_traverse_overlapping (tree, tree, 
-				    (GtsBBTreeTraverseFunc) self_intersecting,
-				    d);
-  gts_bb_tree_destroy (tree, TRUE);
-
-  return self_inter;
-}
-
-static void add_intersecting (GtsBBox * bb1, GtsBBox * bb2, 
-			      GtsSurface * intersected)
-{
-  gts_surface_add_face (intersected, bb1->bounded);
-  gts_surface_add_face (intersected, bb2->bounded);
-}
-
-/**
- * gts_surface_is_self_intersecting:
- * @s: a #GtsSurface.
- *
- * Returns: a new #GtsSurface containing the faces of @s which are
- * self-intersecting or %NULL if no faces of @s are self-intersecting.
- */
-GtsSurface * gts_surface_is_self_intersecting (GtsSurface * s)
-{
-  GtsSurface * intersected;
-
-  g_return_val_if_fail (s != NULL, NULL);
-
-  intersected = gts_surface_new (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass),
-				 s->face_class,
-				 s->edge_class,
-				 s->vertex_class);
-  if (!gts_surface_foreach_intersecting_face (s,
-		      (GtsBBTreeTraverseFunc) add_intersecting, intersected)) {
-    gts_object_destroy (GTS_OBJECT (intersected));
-    intersected = NULL;
-  }
-  return intersected;
-}
diff --git a/src/gts/cdt.c b/src/gts/cdt.c
deleted file mode 100644
index 2038ab5..0000000
--- a/src/gts/cdt.c
+++ /dev/null
@@ -1,1175 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#ifdef HAVE_CONFIG_H
-# include <config.h>
-#endif
-
-
-#include <math.h>
-#include "gts.h"
-
-#ifdef USE_SURFACE_BTREE
-
-static gint find_closest (GtsTriangle * t, gpointer value, gpointer * data)
-{
-  guint * ns = data[2];
-  guint * n = data[3];
-
-  if (*n >= *ns)
-    return TRUE;
-  else {
-    gdouble * dmin = data[0];
-    gpointer * closest = data[1];
-    GtsPoint * p = data[4];
-
-    if (gts_triangle_orientation (t) > 0.) {
-      GtsPoint * p1 = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
-      gdouble d = (p->x - p1->x)*(p->x - p1->x) + (p->y - p1->y)*(p->y - p1->y);
-      
-      if (d < *dmin) {
-	*dmin = d;
-	*closest = t;
-      }
-      (*n)++;
-    }
-  }
-  return FALSE;
-}
-
-/* select the face closest to @p among n^1/3 randomly picked faces
- *  of @surface */
-static GtsFace * closest_face (GtsSurface * s, GtsPoint * p)
-{
-  guint n = 0, nt, ns;
-  gdouble dmin = G_MAXDOUBLE;
-  GtsFace * closest = NULL;
-  gpointer data[5];
-
-  nt = gts_surface_face_number (s);
-  if (!nt)
-    return NULL;
-  ns = exp (log ((gdouble) nt)/3.);
-
-  data[0] = &dmin;
-  data[1] = &closest;
-  data[2] = &ns;
-  data[3] = &n;
-  data[4] = p;
-  g_tree_traverse (s->faces, (GTraverseFunc) find_closest, G_IN_ORDER, data);
-
-  return closest;
-}
-
-#else /* not USE_SURFACE_BTREE */
-
-typedef struct _SFindClosest SFindClosest; 
-
-struct _SFindClosest {
-  gdouble dmin; 
-  GtsFace *closest;
-  GtsPoint * p;
-  gint stop;
-};
-
-#  if GLIB_CHECK_VERSION(2,4,0)
-/* finally, with g_hash_table_find we are able to stop iteration over the hash
-   table in the middle */
-
-static gboolean find_closest (gpointer key, gpointer value, gpointer user_data)
-{
-  SFindClosest * data = (SFindClosest *) user_data;
-  GtsFace * f = GTS_FACE (value);
-  
-  if (gts_triangle_orientation (GTS_TRIANGLE (f)) > 0.) {
-    GtsPoint * p1 = GTS_POINT (GTS_SEGMENT (GTS_TRIANGLE (f)->e1)->v1);
-    gdouble d = ((data->p->x - p1->x)*(data->p->x - p1->x) + 
-		 (data->p->y - p1->y)*(data->p->y - p1->y));
-
-    if (d < data->dmin) {
-      data->dmin = d;
-      data->closest = f;
-    }
-  }
-  data->stop--;
-  return !(data->stop > 0);
-}
-
-static GtsFace * closest_face (GtsSurface * s, GtsPoint * p)
-{
-  SFindClosest fc;
-
-  fc.dmin = G_MAXDOUBLE;
-  fc.closest = NULL;
-  fc.p = p;
-  fc.stop = (gint) exp (log ((gdouble) g_hash_table_size (s->faces))/3.);
-  g_hash_table_find (s->faces, find_closest, &fc);
-  
-  return fc.closest;
-}
-
-#  else /* VERSION < 2.4.0 */
-
-static void
-find_closest (gpointer key, gpointer value, gpointer user_data)
-{
-  SFindClosest * data = (SFindClosest *) user_data;
-  GtsFace * f = GTS_FACE (value);
-
-  if (gts_triangle_orientation (GTS_TRIANGLE (f)) > 0.) {
-    GtsPoint * p1 = GTS_POINT (GTS_SEGMENT (GTS_TRIANGLE (f)->e1)->v1);
-    gdouble d = ((data->p->x - p1->x)*(data->p->x - p1->x) +
-		 (data->p->y - p1->y)*(data->p->y - p1->y));
-
-    if (d < data->dmin) {
-      data->dmin = d;
-      data->closest = f;
-    }
-  }
-  data->stop--;
-}
-
-/* select the face closest to @p among n^1/3 randomly picked faces
- * of @surface */
-static GtsFace * closest_face (GtsSurface * s, GtsPoint * p)
-{
-  SFindClosest fc;
-
-  if (!g_hash_table_size (s->faces))
-    return NULL;
-
-  fc.dmin = G_MAXDOUBLE;
-  fc.closest = NULL;
-  fc.p = p;
-  fc.stop = (gint) exp (log ((gdouble) g_hash_table_size (s->faces))/3.);
-  g_hash_table_foreach (s->faces, find_closest, &fc);
-  return fc.closest;
-}
-#  endif /* VERSION < 2.4.0 */
-#endif /* not USE_SURFACE_BTREE */
-
-/* returns the face belonging to @surface and neighbor of @f via @e */
-static GtsFace * neighbor (GtsFace * f,
-			   GtsEdge * e,
-			   GtsSurface * surface)
-{
-  GSList * i = e->triangles;
-  GtsTriangle * t = GTS_TRIANGLE (f);
-
-  while (i) {
-    GtsTriangle * t1 = i->data;
-    if (t1 != t &&
-	GTS_IS_FACE (t1) &&
-	gts_face_has_parent_surface (GTS_FACE (t1), surface))
-      return GTS_FACE (t1);
-    i = i->next;
-  }
-  return NULL;
-}
-
-/* given a triangle @t and a segment s (@o -> @p). 
-   @o must be in @t. Returns the
-   edge of @t which is intersected by s or %NULL if @p is also
-   contained in @t (on_summit is set to %FALSE) or if s intersects @t 
-   exactly on one of its summit (on_summit is set to %TRUE). */
-static GtsEdge * triangle_next_edge (GtsTriangle * t,
-				     GtsPoint * o, GtsPoint * p,
-				     gboolean * on_summit)
-{
-  GtsVertex * v1, * v2, * v3;
-  GtsEdge * e1, * e2, * e3;
-  gdouble orient = 0.0;
-  
-  gts_triangle_vertices_edges (t, NULL,
-			       &v1, &v2, &v3, 
-			       &e1, &e2, &e3);
-
-  *on_summit = FALSE;
-  orient = gts_point_orientation (o, GTS_POINT (v1), p);
-  if (orient > 0.0) {
-    orient = gts_point_orientation (o, GTS_POINT (v2), p);
-    if (orient > 0.0) {
-      if (gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), p) >= 0.0)
-	return NULL;
-      return e2;
-    }
-    if (orient < 0.0) {
-      if (gts_point_orientation (GTS_POINT (v1), GTS_POINT (v2), p) >= 0.0)
-	return NULL;
-      return e1;
-    }
-    if (gts_point_orientation (GTS_POINT (v1), GTS_POINT (v2), p) < 0.0)
-      *on_summit = TRUE;
-    return NULL;
-  }
-
-  if (orient < 0.0) {
-    orient = gts_point_orientation (o, GTS_POINT (v3), p);
-    if (orient > 0.0) {
-      if (gts_point_orientation (GTS_POINT (v3), GTS_POINT (v1), p) >= 0.0)
-	return NULL;
-      return e3;
-    }
-    if (orient < 0.0) {
-      if (gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), p) >= 0.0)
-	return NULL;
-      return e2;
-    }
-    if (gts_point_orientation (GTS_POINT (v3), GTS_POINT (v1), p) < 0.0)
-      *on_summit = TRUE;
-    return NULL;
-  }
-  
-  if (gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), p) < 0.0)
-    return e2;
-  if (gts_point_orientation (GTS_POINT (v1), GTS_POINT (v2), p) < 0.0)
-    *on_summit = TRUE;
-  return NULL;
-}
-
-static void triangle_barycenter (GtsTriangle * t, GtsPoint * b)
-{
-  GtsPoint * p = GTS_POINT (gts_triangle_vertex (t));
-  b->x = (p->x + 
-	  GTS_POINT (GTS_SEGMENT(t->e1)->v1)->x +
-	  GTS_POINT (GTS_SEGMENT(t->e1)->v2)->x)/3.;
-  b->y = (p->y + 
-	  GTS_POINT (GTS_SEGMENT(t->e1)->v1)->y +
-	  GTS_POINT (GTS_SEGMENT(t->e1)->v2)->y)/3.;
-}
-
-static GtsFace * point_locate (GtsPoint * o,
-			       GtsPoint * p,
-			       GtsFace * f,
-			       GtsSurface * surface)
-{
-  GtsEdge * prev;
-  gboolean on_summit;
-  GtsVertex * v1, * v2, * v3;
-  GtsEdge * e2, * e3;    
-  
-  prev = triangle_next_edge (GTS_TRIANGLE (f), o, p, &on_summit);
-
-  if (!prev) {
-    GtsFace * f1;
-
-    if (!on_summit)
-      return f; /* p is inside f */
-
-    /* s intersects f exactly on a summit: restarts from a neighbor of f */
-    if ((f1 = neighbor (f, GTS_TRIANGLE (f)->e1, surface)) ||
-	(f1 = neighbor (f, GTS_TRIANGLE (f)->e2, surface)) ||
-	(f1 = neighbor (f, GTS_TRIANGLE (f)->e3, surface))) {
-      triangle_barycenter (GTS_TRIANGLE (f1), o);
-      return point_locate (o, p, f1, surface);
-    }
-    return NULL;
-  }
-  
-  f = neighbor (f, prev, surface);
-  if (f)
-    gts_triangle_vertices_edges (GTS_TRIANGLE (f), prev, 
-				 &v1, &v2, &v3, &prev, &e2, &e3);
-  while (f) {
-    gdouble orient = gts_point_orientation (o, GTS_POINT (v3), p);
-
-    if (orient < 0.0) {
-      if (gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), p) >= 0.0)
-	return f; /* p is inside f */
-      f = neighbor (f, e2, surface);
-      prev = e2;
-      v1 = v3;      
-    }
-    else if (orient > 0.0) {
-      if (gts_point_orientation (GTS_POINT (v3), GTS_POINT (v1), p) >= 0.0)
-	return f; /* p is inside f */
-      f = neighbor (f, e3, surface);
-      prev = e3;
-      v2 = v3;
-    }
-    else {
-      GtsFace * f1;
-
-      if (gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), p) >= 0.0)
-	return f; /* p is inside f */
-
-      /* s intersects f exactly on v3: restarts from a neighbor of f */
-      if ((f1 = neighbor (f, e2, surface)) ||
-	  (f1 = neighbor (f, e3, surface))) {
-	triangle_barycenter (GTS_TRIANGLE (f1), o);
-	return point_locate (o, p, f1, surface);
-      }
-      return NULL;
-    }
-    /* update e2, e3, v3 for the new triangle */
-    if (f) {
-      if (prev == GTS_TRIANGLE (f)->e1) {
-	e2 = GTS_TRIANGLE (f)->e2; e3 = GTS_TRIANGLE (f)->e3;
-      }
-      else if (prev == GTS_TRIANGLE (f)->e2) {
-	e2 = GTS_TRIANGLE (f)->e3; e3 = GTS_TRIANGLE (f)->e1;
-      }
-      else {
-	e2 = GTS_TRIANGLE (f)->e1; e3 = GTS_TRIANGLE (f)->e2;
-      }
-      if (GTS_SEGMENT (e2)->v1 == v1 || GTS_SEGMENT (e2)->v1 == v2)
-	v3 = GTS_SEGMENT (e2)->v2;
-      else
-	v3 = GTS_SEGMENT (e2)->v1;
-    }
-  }
-  return NULL;
-}
-
-/**
- * gts_point_locate:
- * @p: a #GtsPoint.
- * @surface: a #GtsSurface.
- * @guess: %NULL or a face of @surface close to @p.
- *
- * Locates the face of the planar projection of @surface containing
- * @p. The planar projection of @surface must define a connected set
- * of triangles without holes and bounded by a convex boundary. The
- * algorithm is randomized and performs in O(n^1/3) expected time
- * where n is the number of triangles of @surface.
- *
- * If a good @guess is given the point location can be significantly faster.
- *
- * Returns: a #GtsFace of @surface containing @p or %NULL if @p is not
- * contained within the boundary of @surface.  
- */
-GtsFace * gts_point_locate (GtsPoint * p, 
-			    GtsSurface * surface,
-			    GtsFace * guess)
-{
-  GtsFace * fr;
-  GtsPoint * o;
-
-  g_return_val_if_fail (p != NULL, NULL);
-  g_return_val_if_fail (surface != NULL, NULL);
-  g_return_val_if_fail (guess == NULL || 
-			gts_face_has_parent_surface (guess, surface), NULL);
-
-  if (guess == NULL)
-    guess = closest_face (surface, p);
-  else
-    g_return_val_if_fail (gts_triangle_orientation (GTS_TRIANGLE (guess)) > 0., NULL);
-
-  if (guess == NULL)
-    return NULL;
-
-  o = GTS_POINT (gts_object_new (GTS_OBJECT_CLASS (gts_point_class ())));
-  triangle_barycenter (GTS_TRIANGLE (guess), o);
-  fr = point_locate (o, p, guess, surface);
-  gts_object_destroy (GTS_OBJECT (o));
-
-  return fr;
-}
-
-
-/**
- * gts_constraint_class:
- *
- * Returns: the #GtsConstraintClass.
- */
-GtsConstraintClass * gts_constraint_class (void)
-{
-  static GtsConstraintClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo constraint_info = {
-      "GtsConstraint",
-      sizeof (GtsConstraint),
-      sizeof (GtsConstraintClass),
-      (GtsObjectClassInitFunc) NULL,
-      (GtsObjectInitFunc) NULL,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_edge_class ()), 
-				  &constraint_info);
-  }
-
-  return klass;
-}
-
-static void split_list (GtsListFace * f, GtsListFace * f1, GtsListFace * f2, 
-			GtsPoint * p1, GtsPoint * p2,
-			GSList ** last1, GSList ** last2)
-{
-  GSList * i = f->points, * l1 = *last1, * l2 = *last2;
-
-  while (i) {
-    GtsPoint * p = i->data;
-    
-    if (gts_point_orientation (p1, p2, p) >= 0.) {
-      if (l1) l1->next = i; else f1->points = i;
-      l1 = i;
-    }
-    else {
-      if (l2) l2->next = i; else f2->points = i;
-      l2 = i;
-    }
-    i = i->next;
-  }
-  f->points = NULL;
-  *last1 = l1;
-  *last2 = l2;
-}
-
-/* cf. figure misc/swap.fig */
-static void swap_if_in_circle (GtsFace * f1,
-			       GtsVertex * v1, 
-			       GtsVertex * v2, 
-			       GtsVertex * v3,
-			       GtsEdge * e1, 
-			       GtsEdge * e2, 
-			       GtsEdge * e3,
-			       GtsSurface * surface)
-{
-  GtsFace * f2;
-  GtsEdge * e4, *e5;
-  GtsVertex * v4;
-
-  if (GTS_IS_CONSTRAINT (e1)) /* @e1 is a constraint can not swap */
-    return;
-
-  f2 = neighbor (f1, e1, surface);
-  if (f2 == NULL) /* @e1 is a boundary of @surface */
-    return;
-
-  if (GTS_TRIANGLE (f2)->e1 == e1) {
-    e4 = GTS_TRIANGLE (f2)->e2; e5 = GTS_TRIANGLE (f2)->e3;
-  }
-  else if (GTS_TRIANGLE (f2)->e2 == e1) {
-    e4 = GTS_TRIANGLE (f2)->e3; e5 = GTS_TRIANGLE (f2)->e1;
-  }
-  else {
-    e4 = GTS_TRIANGLE (f2)->e1; e5 = GTS_TRIANGLE (f2)->e2;
-  }
-  if (GTS_SEGMENT (e4)->v1 == GTS_SEGMENT (e1)->v1 || 
-      GTS_SEGMENT (e4)->v1 == GTS_SEGMENT (e1)->v2)
-    v4 = GTS_SEGMENT (e4)->v2;
-  else
-    v4 = GTS_SEGMENT (e4)->v1;
-
-  if (gts_point_in_circle (GTS_POINT (v4), GTS_POINT (v1), 
-			   GTS_POINT (v2), GTS_POINT (v3)) > 0.0) {
-    GtsEdge * en;
-    GtsSegment * sn = gts_vertices_are_connected (v3, v4);
-    GtsFace * f3, * f4;
-
-    if (!GTS_IS_EDGE (sn))
-      en = gts_edge_new (surface->edge_class, v3, v4);
-    else
-      en = GTS_EDGE (sn);
-
-    f3 = gts_face_new (surface->face_class, en, e5, e2);
-    gts_object_attributes (GTS_OBJECT (f3), GTS_OBJECT (f1));
-    f4 = gts_face_new (surface->face_class, en, e3, e4);
-    gts_object_attributes (GTS_OBJECT (f4), GTS_OBJECT (f2));
-    
-    if (GTS_IS_LIST_FACE (f3)) {
-      GSList * last3 = NULL, * last4 = NULL;
-
-      if (GTS_IS_LIST_FACE (f1))
-	split_list (GTS_LIST_FACE (f1), GTS_LIST_FACE (f3), GTS_LIST_FACE (f4),
-		    GTS_POINT (v3), GTS_POINT (v4), &last3, &last4);
-      if (GTS_IS_LIST_FACE (f2))
-	split_list (GTS_LIST_FACE (f2), GTS_LIST_FACE (f3), GTS_LIST_FACE (f4),
-		    GTS_POINT (v3), GTS_POINT (v4), &last3, &last4);
-      if (last3) last3->next = NULL;
-      if (last4) last4->next = NULL;
-    }
-
-    gts_surface_remove_face (surface, f1);
-    gts_surface_remove_face (surface, f2);
-    gts_surface_add_face (surface, f3);
-    gts_surface_add_face (surface, f4);
-
-    swap_if_in_circle (f3, v4, v2, v3, e5, e2, en, surface);
-    swap_if_in_circle (f4, v1, v4, v3, e4, en, e3, surface);
-  }
-}
-
-/**
- * gts_delaunay_add_vertex_to_face:
- * @surface: a #GtsSurface.
- * @v: a #GtsVertex.
- * @f: a #GtsFace belonging to @surface.
- *
- * Adds vertex @v to the face @f of the Delaunay triangulation defined
- * by @surface.
- *
- * Returns: %NULL is @v has been successfully added to @surface or was
- * already contained in @surface or a #GtsVertex having the same x and
- * y coordinates as @v.  
- */
-GtsVertex * gts_delaunay_add_vertex_to_face (GtsSurface * surface, 
-					     GtsVertex * v,
-					     GtsFace * f)
-{
-  GtsEdge * e1, * e2, * e3;
-  GtsSegment * s4, * s5, * s6;
-  GtsEdge * e4, * e5, * e6;
-  GtsVertex * v1, * v2, * v3;
-  GtsFace * nf[3];
-
-  g_return_val_if_fail (surface != NULL, v);
-  g_return_val_if_fail (v != NULL, v);
-  g_return_val_if_fail (f != NULL, v);
-
-  gts_triangle_vertices_edges (GTS_TRIANGLE (f), NULL, 
-			       &v1, &v2, &v3, &e1, &e2, &e3);
-  if (v == v1 || v == v2 || v == v3) /* v already in @surface */
-    return NULL;
-  if (GTS_POINT (v)->x == GTS_POINT (v1)->x &&
-      GTS_POINT (v)->y == GTS_POINT (v1)->y)
-    return v1;
-  if (GTS_POINT (v)->x == GTS_POINT (v2)->x &&
-      GTS_POINT (v)->y == GTS_POINT (v2)->y)
-    return v2;
-  if (GTS_POINT (v)->x == GTS_POINT (v3)->x &&
-      GTS_POINT (v)->y == GTS_POINT (v3)->y)
-    return v3;
-
-  s4 = gts_vertices_are_connected (v, v1);
-  if (!GTS_IS_EDGE (s4))
-    e4 = gts_edge_new (surface->edge_class, v, v1);
-  else
-    e4 = GTS_EDGE (s4);
-  s5 = gts_vertices_are_connected (v, v2);
-  if (!GTS_IS_EDGE (s5))
-    e5 = gts_edge_new (surface->edge_class, v, v2);
-  else
-    e5 = GTS_EDGE (s5);
-  s6 = gts_vertices_are_connected (v, v3);
-  if (!GTS_IS_EDGE (s6))
-    e6 = gts_edge_new (surface->edge_class, v, v3);
-  else
-    e6 = GTS_EDGE (s6);
-
-  /* cf. figure misc/swap.fig */
-  nf[0] = gts_face_new (surface->face_class, e4, e1, e5);
-  gts_object_attributes (GTS_OBJECT (nf[0]), GTS_OBJECT (f));
-  nf[1] = gts_face_new (surface->face_class, e5, e2, e6);
-  gts_object_attributes (GTS_OBJECT (nf[1]), GTS_OBJECT (f));
-  nf[2] = gts_face_new (surface->face_class, e6, e3, e4);
-  gts_object_attributes (GTS_OBJECT (nf[2]), GTS_OBJECT (f));
-
-  if (GTS_IS_LIST_FACE (f) && GTS_IS_LIST_FACE (nf[0])) {
-    GSList * i = GTS_LIST_FACE (f)->points, * last[3] = { NULL, NULL, NULL };
-
-    while (i) {
-      GtsPoint * p = i->data;
-      GSList * next = i->next;
-      guint j;
-      
-      if (p != GTS_POINT (v)) {
-	if (gts_point_orientation (GTS_POINT (v), GTS_POINT (v1), p) >= 0.) {
-	  gdouble o = gts_point_orientation (GTS_POINT (v), GTS_POINT (v2), p);
-
-	  if (o != 0.)
-	    j = o > 0. ? 1 : 0;
-	  else
-	    j = gts_point_orientation (GTS_POINT (v), GTS_POINT (v3), p) 
-	      > 0. ? 0 : 1;
-	}
-	else if (gts_point_orientation (GTS_POINT (v), GTS_POINT (v3), p) > 0.)
-	  j = 2;
-	else
-	  j = 1;
-	if (last[j])
-	  last[j]->next = i; 
-	else 
-	  GTS_LIST_FACE (nf[j])->points = i;
-	last[j] = i;
-      }
-      else
-	g_slist_free_1 (i);
-      i = next;
-    }
-    GTS_LIST_FACE (f)->points = NULL;
-    if (last[0]) last[0]->next = NULL;
-    if (last[1]) last[1]->next = NULL;
-    if (last[2]) last[2]->next = NULL;
-  }
-
-  gts_surface_remove_face (surface, f);
-  gts_surface_add_face (surface, nf[0]);
-  gts_surface_add_face (surface, nf[1]);
-  gts_surface_add_face (surface, nf[2]);
-
-  swap_if_in_circle (nf[0], v1, v2, v, e1, e5, e4, surface);
-  swap_if_in_circle (nf[1], v2, v3, v, e2, e6, e5, surface);
-  swap_if_in_circle (nf[2], v3, v1, v, e3, e4, e6, surface);
-
-  return NULL;
-}
-
-/** 
- * gts_delaunay_add_vertex: 
- * @surface: a #GtsSurface.  
- * @v: a #GtsVertex.  
- * @guess: %NULL or a #GtsFace belonging to @surface to be used as an initial
- * guess for point location.
- *
- * Adds vertex @v to the Delaunay triangulation defined by
- * @surface. If @v is not contained in the convex hull bounding
- * @surface, @v is not added to the triangulation.
- *
- * Returns: %NULL is @v has been successfully added to @surface or was
- * already contained in @surface, @v if @v is not contained in the
- * convex hull bounding surface or a #GtsVertex having the same x and
- * y coordinates as @v.  
- */
-GtsVertex * gts_delaunay_add_vertex (GtsSurface * surface, 
-				     GtsVertex * v,
-				     GtsFace * guess)
-{
-  GtsFace * f;
-
-  g_return_val_if_fail (surface != NULL, v);
-  g_return_val_if_fail (v != NULL, v);
-
-  if (!(f = gts_point_locate (GTS_POINT (v), surface, guess)))
-    return v;
-  return gts_delaunay_add_vertex_to_face (surface, v, f);
-}
-
-static gboolean polygon_in_circle (GSList * poly,
-				   GtsPoint * p1, 
-				   GtsPoint * p2,
-				   GtsPoint * p3)
-{
-  GtsVertex * v1 = NULL, * v2 = NULL;
-
-  while (poly) {
-    GtsSegment * s = poly->data;
-    GtsVertex * v;
-    v = s->v1;
-    if (v != v1 && v != v2 &&
-	v != GTS_VERTEX (p1) &&
-	v != GTS_VERTEX (p2) &&
-	v != GTS_VERTEX (p3) &&
-	gts_point_in_circle (GTS_POINT (v), p1, p2, p3) > 0.)
-      return TRUE;
-    v = s->v2;
-    if (v != v1 && v != v2 &&
-	v != GTS_VERTEX (p1) &&
-	v != GTS_VERTEX (p2) &&
-	v != GTS_VERTEX (p3) &&
-	gts_point_in_circle (GTS_POINT (v), p1, p2, p3) > 0.)
-      return TRUE;
-    v1 = s->v1;
-    v2 = s->v2;
-    poly = poly->next;
-  }
-  return FALSE;
-}
-
-static void triangulate_polygon (GSList * poly, 
-				 GtsSurface * surface,
-				 GtsFace * ref)
-{
-  GSList * i, * poly1, * poly2;
-  GtsVertex * v1, * v2, * v3 = NULL;
-  gboolean found = FALSE;
-  GtsSegment * s, * s1, * s2;
-  GtsEdge * e1, * e2;
-  GtsFace * f;
-
-  if (poly == NULL || poly->next == NULL) {
-    g_slist_free (poly);
-    return;
-  }
-
-  s = poly->data;
-  s1 = poly->next->data;
-  if (s->v1 == s1->v1 || s->v1 == s1->v2) {
-    v1 = s->v2;
-    v2 = s->v1;
-  }
-  else {
-    g_assert (s->v2 == s1->v1 || s->v2 == s1->v2);
-    v1 = s->v1;
-    v2 = s->v2;
-  }
-
-  i = poly->next;
-  v3 = v2;
-  while (i && !found) {
-    s1 = i->data;
-    if (s1->v1 == v3)
-      v3 = s1->v2;
-    else {
-      g_assert (s1->v2 == v3);
-      v3 = s1->v1;
-    }
-    if (v3 != v1 &&
-	gts_point_orientation (GTS_POINT (v1), 
-			       GTS_POINT (v2), 
-			       GTS_POINT (v3)) >= 0. &&
-	!polygon_in_circle (poly, 
-			    GTS_POINT (v1), 
-			    GTS_POINT (v2), 
-			    GTS_POINT (v3)))
-      found = TRUE;
-    else 
-      i = i->next;
-  }
-
-  if (!found) {
-    g_slist_free (poly);
-    return;
-  }
-
-  s1 = gts_vertices_are_connected (v2, v3);
-  if (!GTS_IS_EDGE (s1))
-    e1 = gts_edge_new (surface->edge_class, v2, v3);
-  else
-    e1 = GTS_EDGE (s1);
-  s2 = gts_vertices_are_connected (v3, v1);
-  if (!GTS_IS_EDGE (s2))
-    e2 = gts_edge_new (surface->edge_class, v3, v1);
-  else
-    e2 = GTS_EDGE (s2);
-  f = gts_face_new (surface->face_class, GTS_EDGE (s), e1, e2);
-  gts_object_attributes (GTS_OBJECT (f), GTS_OBJECT (ref));
-  gts_surface_add_face (surface, f);
-
-  poly1 = poly->next;
-  g_slist_free_1 (poly);
-  if (i->next && e2 != i->next->data)
-    poly2 = g_slist_prepend (i->next, e2);
-  else
-    poly2 = i->next;
-  if (e1 != i->data)
-    i->next = g_slist_prepend (NULL, e1);
-  else
-    i->next = NULL;
-
- triangulate_polygon (poly1, surface, ref);
- triangulate_polygon (poly2, surface, ref);
-}
-
-/**
- * gts_delaunay_remove_vertex:
- * @surface: a #GtsSurface.
- * @v: a #GtsVertex.
- *
- * Removes @v from the Delaunay triangulation defined by @surface and
- * restores the Delaunay property. Vertex @v must not be used by any
- * constrained edge otherwise the triangulation is not guaranteed to
- * be Delaunay.  
- */
-void gts_delaunay_remove_vertex (GtsSurface * surface, GtsVertex * v)
-{
-  GSList * triangles, * i;
-  GtsFace * ref = NULL;
-
-  g_return_if_fail (surface != NULL);
-  g_return_if_fail (v != NULL);
-
-  i = triangles = gts_vertex_triangles (v, NULL);
-  while (i && !ref) {
-    if (GTS_IS_FACE (i->data) &&
-	gts_face_has_parent_surface (i->data, surface))
-      ref = i->data;
-    i = i->next;
-  }
-  if (!ref) {
-    g_slist_free (triangles);
-    g_return_if_fail (ref);
-  }
-  triangulate_polygon (gts_vertex_fan_oriented (v, surface), surface, ref);
-  i = triangles;
-  while (i) {
-    if (GTS_IS_FACE (i->data) &&
-	gts_face_has_parent_surface (i->data, surface))
-      gts_surface_remove_face (surface, i->data);
-    i = i->next;
-  }
-  g_slist_free (triangles);
-}
-
-#define NEXT_CUT(edge, edge1, list) { next = neighbor (f, edge, surface);\
-                                      remove_triangles (e, surface);\
-                                      if (!constraint && !e->triangles)\
-				        gts_object_destroy (GTS_OBJECT (e));\
-                                      g_assert (next);\
-				      *list = g_slist_prepend (*list, edge1);\
-                                      return g_slist_concat (constraint,\
-                                        remove_intersected_edge (s, edge,\
-					       next, surface, left, right));\
-                                    }
-
-static void remove_triangles (GtsEdge * e, GtsSurface * s)
-{
-  GSList * i = e->triangles;
-
-  while (i) {
-    GSList * next = i->next;
-
-    if (GTS_IS_FACE (i->data) && gts_face_has_parent_surface (i->data, s))
-      gts_surface_remove_face (s, i->data);
-    i = next;
-  }
-}
-
-static GSList * 
-remove_intersected_edge (GtsSegment * s,
-			 GtsEdge * e,
-			 GtsFace * f,
-			 GtsSurface * surface,
-			 GSList ** left, GSList ** right)
-{
-  GtsVertex * v1, * v2, * v3;
-  GtsEdge * e1, * e2;
-  gdouble o1, o2;
-  GtsFace * next;
-  GSList * constraint = NULL;
-
-  if (GTS_IS_CONSTRAINT (e))
-    constraint = g_slist_prepend (NULL, e);
-
-  gts_triangle_vertices_edges (GTS_TRIANGLE (f), e, 
-			       &v1, &v2, &v3, &e, &e1, &e2);
-  
-  o1 = gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), 
-			      GTS_POINT (s->v2));
-  o2 = gts_point_orientation (GTS_POINT (v3), GTS_POINT (v1), 
-			      GTS_POINT (s->v2));
-
-  if (o1 == 0. && o2 == 0.) {
-/*    if(o2 != 0.) {
-      fprintf(stderr, "o1 = %f o2 = %f\n", o1, o2);
-      fprintf(stderr, "v1 = %f, %f\n", GTS_POINT(v1)->x, GTS_POINT(v1)->y);
-      fprintf(stderr, "v2 = %f, %f\n", GTS_POINT(v2)->x, GTS_POINT(v2)->y);
-      fprintf(stderr, "v3 = %f, %f\n", GTS_POINT(v3)->x, GTS_POINT(v3)->y);
-      fprintf(stderr, "s->v2 = %f, %f\n", GTS_POINT(s->v2)->x, GTS_POINT(s->v2)->y);
-
-      g_assert (o2 == 0.);
-    }*/
- //   if(o2 == 0.) {
-      remove_triangles (e, surface);
-      if (!constraint && !e->triangles)
-        gts_object_destroy (GTS_OBJECT (e));
-      *left = g_slist_prepend (*left, e2);
-      *right = g_slist_prepend (*right, e1);
-//    }
-  }
-  else if (o1 > 0.) {
-    g_assert (o2 <= 0.);
-    NEXT_CUT (e2, e1, right)
-  }
-  else if (o2 >= 0.)
-    NEXT_CUT (e1, e2, left)
-  else {
-    gdouble o3 = gts_point_orientation (GTS_POINT (s->v1), GTS_POINT (s->v2),
-					GTS_POINT (v3));
-    if (o3 > 0.)
-      NEXT_CUT (e1, e2, left)
-    else
-      NEXT_CUT (e2, e1, right)
-  }
-  return constraint;
-}
-
-static GSList * 
-remove_intersected_vertex (GtsSegment * s,
-			   GtsVertex * v,
-			   GtsSurface * surface,
-			   GSList ** left,
-			   GSList ** right,
-			   GtsFace ** ref)
-{
-  GSList * triangles = gts_vertex_triangles (v, NULL);
-  GSList * i;
-
-  i = triangles;
-  while (i) {
-    GtsTriangle * t = i->data;
-    if (GTS_IS_FACE (t) && 
-	gts_face_has_parent_surface (GTS_FACE (t), surface)) {
-      GtsVertex * v1, * v2, * v3;
-      gdouble o1, o2;
-
-      gts_triangle_vertices (t, &v1, &v2, &v3);
-      if (v == v2) {
-	v2 = v3;
-	v3 = v1;
-      }
-      else if (v == v3) {
-	v3 = v2;
-	v2 = v1;	
-      }
-      else
-	g_assert (v == v1);
-
-      if ((o1 = gts_point_orientation (GTS_POINT (v), GTS_POINT (v2),
-				       GTS_POINT (s->v2))) >= 0. &&
-	  (o2 = gts_point_orientation (GTS_POINT (v3), GTS_POINT (v),
-				       GTS_POINT (s->v2))) >= 0.) {
-	gdouble o3 = gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3),
-					    GTS_POINT (s->v2));
-	GtsEdge * e = gts_triangle_edge_opposite (t, v);
-	GtsEdge * e1, * e2;
-	GtsFace * next = neighbor (GTS_FACE (t), e, surface);
-
-	*ref = GTS_FACE (t);
-	gts_triangle_vertices_edges (t, e, &v2, &v3, &v, &e, &e2, &e1);
-
-	g_slist_free (triangles);
-
-	if (o3 >= 0.) /* @s->v2 is inside (or on the edge) of t */
-	  return NULL;
-
-	gts_allow_floating_faces = TRUE;
-	gts_surface_remove_face (surface, GTS_FACE (t));
-	gts_allow_floating_faces = FALSE;
-
-	*left = g_slist_prepend (*left, e2);
-	*right = g_slist_prepend (*right, e1);
-
-	g_assert (next);
-	return remove_intersected_edge (s, e, next, surface, left, right);
-      }
-    }
-    i = i->next;
-  }
-
-  g_assert_not_reached ();
-  return NULL;
-}
-
-/**
- * gts_delaunay_add_constraint:
- * @surface: a #GtsSurface.
- * @c: a #GtsConstraint.
- *
- * Add constraint @c to the constrained Delaunay triangulation defined by
- * @surface.
- *
- * Returns: a list of #GtsConstraint conflicting (i.e. intersecting) with @c 
- * which were removed from @surface (%NULL if there was none).
- */
-GSList * gts_delaunay_add_constraint (GtsSurface * surface,
-				      GtsConstraint * c)
-{
-  GSList * constraints;
-  GtsVertex * v1, * v2;
-  GSList * left = NULL, * right = NULL;
-  GtsFace * ref = NULL;
-
-  g_return_val_if_fail (surface != NULL, NULL);
-  g_return_val_if_fail (c != NULL, NULL);
-  g_return_val_if_fail (GTS_IS_CONSTRAINT (c), NULL);
-  
-  v1 = GTS_SEGMENT (c)->v1;
-  v2 = GTS_SEGMENT (c)->v2;
-  
-  gts_allow_floating_edges = TRUE;
-  constraints = remove_intersected_vertex (GTS_SEGMENT (c), v1, surface,
-					   &left, &right, &ref);
-  gts_allow_floating_edges = FALSE;
-#if 1
-  triangulate_polygon (g_slist_prepend (g_slist_reverse (right), c), 
-		       surface, ref);
-  triangulate_polygon (g_slist_prepend (left, c), 
-		       surface, ref);
-#else
-  right = g_slist_prepend (g_slist_reverse (right), c);
-  left = g_slist_prepend (left, c);
-  {
-    FILE * fp0 = fopen ("hole", "wt");
-    FILE * fp1 = fopen ("right", "wt");
-    FILE * fp2 = fopen ("left", "wt");
-    GSList * i = left;
-
-    gts_surface_write (surface, fp0);
-    fclose (fp0);
- 
-    fprintf (fp2, "LIST {\n");
-    while (i) {
-      GtsSegment * s = i->data;
-      fprintf (fp2, 
-	       "# %p: %p->%p\n"
-	       "VECT 1 2 0 2 0 %g %g 0 %g %g 0\n",
-	       s, s->v1, s->v2,
-	       GTS_POINT (s->v1)->x, GTS_POINT (s->v1)->y,
-	       GTS_POINT (s->v2)->x, GTS_POINT (s->v2)->y);
-      i = i->next;
-    }
-    fprintf (fp2, "}\n");
-    fprintf (fp1, "LIST {\n");
-    i = right;
-    while (i) {
-      GtsSegment * s = i->data;
-      fprintf (fp1, 
-	       "# %p: %p->%p\n"
-	       "VECT 1 2 0 2 0 %g %g 0 %g %g 0\n",
-	       s, s->v1, s->v2,
-	       GTS_POINT (s->v1)->x, GTS_POINT (s->v1)->y,
-	       GTS_POINT (s->v2)->x, GTS_POINT (s->v2)->y);
-      i = i->next;
-    }
-    fprintf (fp1, "}\n");
-    fclose (fp1);
-    fclose (fp2);
-  }
-  triangulate_polygon (right, surface);
-  triangulate_polygon (left, surface);
-#endif
-  if (ref && !ref->surfaces) {
-    gts_allow_floating_edges = TRUE;
-    gts_object_destroy (GTS_OBJECT (ref));
-    gts_allow_floating_edges = FALSE;
-  }
-  return constraints;
-}
-
-static void delaunay_check (GtsTriangle * t, gpointer * data)
-{
-  GtsSurface * surface = data[0];
-  GtsFace ** face = data[1];
-
-  if (*face == NULL) {
-    GSList * i, * list;
-    GtsVertex * v1, * v2, * v3;
-
-    gts_triangle_vertices (t, &v1, &v2, &v3);
-    list = gts_vertex_neighbors (v1, NULL, surface);
-    list = gts_vertex_neighbors (v2, list, surface);
-    list = gts_vertex_neighbors (v3, list, surface);
-    i = list;
-    while (i && *face == NULL) {
-      GtsVertex * v = i->data;
-      if (v != v1 && v != v2 && v != v3 &&
-	  gts_point_in_circle (GTS_POINT (v), 
-			       GTS_POINT (v1),
-			       GTS_POINT (v2),  
-			       GTS_POINT (v3)) > 0.)
-	*face = GTS_FACE (t);
-      i = i->next;
-    }
-    g_slist_free (list);
-  }
-}
-
-/**
- * gts_delaunay_check:
- * @surface: a #GtsSurface.
- *
- * Returns: %NULL if the planar projection of @surface is a Delaunay 
- * triangulation (unconstrained), a #GtsFace violating the Delaunay
- * property otherwise.
- */
-GtsFace * gts_delaunay_check (GtsSurface * surface)
-{
-  GtsFace * face = NULL;
-  gpointer data[2];
-
-  g_return_val_if_fail (surface != NULL, FALSE);
-
-  data[0] = surface;
-  data[1] = &face;
-  gts_surface_foreach_face (surface, (GtsFunc) delaunay_check, data);
-
-  return face;
-}
-
-/**
- * gts_delaunay_remove_hull:
- * @surface: a #GtsSurface.
- *
- * Removes all the edges of the boundary of @surface which are not
- * constraints.  
- */
-void gts_delaunay_remove_hull (GtsSurface * surface)
-{
-  GSList * boundary;
-
-  g_return_if_fail (surface != NULL);
-
-  boundary = gts_surface_boundary (surface);
-  gts_allow_floating_edges = TRUE;
-  while (boundary) {
-    GSList * i = boundary;
-    GtsEdge * e = i->data;
-
-    boundary = i->next;
-    g_slist_free_1 (i);
-    if (!GTS_IS_CONSTRAINT (e)) {
-      GtsTriangle * t = GTS_TRIANGLE (gts_edge_is_boundary (e, surface));
-
-      if (t != NULL) {
-	if (t->e1 != e && !GTS_IS_CONSTRAINT (t->e1) &&
-	    !gts_edge_is_boundary (t->e1, surface))
-	  boundary = g_slist_prepend (boundary, t->e1);
-	if (t->e2 != e && !GTS_IS_CONSTRAINT (t->e2) &&
-	    !gts_edge_is_boundary (t->e2, surface))
-	  boundary = g_slist_prepend (boundary, t->e2);
-	if (t->e3 != e && !GTS_IS_CONSTRAINT (t->e3) &&
-	    !gts_edge_is_boundary (t->e3, surface))
-	  boundary = g_slist_prepend (boundary, t->e3);
-	gts_surface_remove_face (surface, GTS_FACE (t));
-      }
-      if (!e->triangles)
-	gts_object_destroy (GTS_OBJECT (e));
-    }
-  }
-  gts_allow_floating_edges = FALSE;
-}
-
-/* GtsListFace: Object */
-
-static void gts_list_face_destroy (GtsObject * object)
-{
-  g_slist_free (GTS_LIST_FACE (object)->points);
-
-  (* GTS_OBJECT_CLASS (gts_list_face_class ())->parent_class->destroy) 
-    (object);
-}
-
-static void gts_list_face_class_init (GtsFaceClass * klass)
-{
-  GTS_OBJECT_CLASS (klass)->destroy = gts_list_face_destroy;
-}
-
-GtsFaceClass * gts_list_face_class (void)
-{
-  static GtsFaceClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo gts_list_face_info = {
-      "GtsListFace",
-      sizeof (GtsListFace),
-      sizeof (GtsFaceClass),
-      (GtsObjectClassInitFunc) gts_list_face_class_init,
-      (GtsObjectInitFunc) NULL,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_face_class ()),
-				  &gts_list_face_info);
-  }
-
-  return klass;
-}
diff --git a/src/gts/container.c b/src/gts/container.c
deleted file mode 100644
index e1dc0fa..0000000
--- a/src/gts/container.c
+++ /dev/null
@@ -1,493 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include "gts.h"
-
-/* GtsContainee */
-
-static void containee_class_init (GtsContaineeClass * klass)
-{
-  klass->remove_container = NULL;
-  klass->add_container = NULL;
-  klass->foreach = NULL;
-  klass->is_contained = NULL;
-  klass->replace = NULL;
-}
-
-GtsContaineeClass * gts_containee_class (void)
-{
-  static GtsContaineeClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo containee_info = {
-      "GtsContainee",
-      sizeof (GtsContainee),
-      sizeof (GtsContaineeClass),
-      (GtsObjectClassInitFunc) containee_class_init,
-      (GtsObjectInitFunc) NULL,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (gts_object_class (),
-				  &containee_info);
-  }
-
-  return klass;
-}
-
-GtsContainee * gts_containee_new (GtsContaineeClass * klass)
-{
-  GtsContainee * object;
-
-  object = GTS_CONTAINEE (gts_object_new (GTS_OBJECT_CLASS (klass)));
-
-  return object;
-}
-
-gboolean gts_containee_is_contained (GtsContainee * item,
-				     GtsContainer * c)
-{
-  g_return_val_if_fail (item != NULL, FALSE);
-  g_return_val_if_fail (c != NULL, FALSE);
-
-  if (GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->is_contained)
-    return
-      (* GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->is_contained) 
-      (item, c);
-  return FALSE;
-}
-
-void gts_containee_replace (GtsContainee * item,
-			    GtsContainee * with)
-{
-  if (GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->replace)
-    (* GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->replace) (item, with);
-  if (GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->foreach) {
-    (* GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->foreach) 
-      (item, (GtsFunc) gts_container_add, with);
-    (* GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->foreach) 
-      (item, (GtsFunc) gts_container_remove, item);
-  }
-}
-
-/* GtsSListContainee */
-
-static void slist_containee_destroy (GtsObject * object)
-{
-  GtsSListContainee * item = GTS_SLIST_CONTAINEE (object);
-  GSList * i;
-
-  i = item->containers;
-  while (i) {
-    GSList * next = i->next;
-
-    gts_container_remove (i->data, GTS_CONTAINEE (item));
-    i = next;
-  }
-  g_assert (item->containers == NULL);
-
-  (* GTS_OBJECT_CLASS (gts_slist_containee_class ())->parent_class->destroy) 
-    (object);
-}
-
-static void slist_containee_remove_container (GtsContainee * i, 
-					      GtsContainer * c)
-{
-  GtsSListContainee * item = GTS_SLIST_CONTAINEE (i);
-  item->containers = g_slist_remove (item->containers, c);
-}
-
-static void slist_containee_add_container (GtsContainee * i, 
-					   GtsContainer * c)
-{
-  GtsSListContainee * item = GTS_SLIST_CONTAINEE (i);
-  if (!g_slist_find (item->containers, c))
-    item->containers = g_slist_prepend (item->containers, c);
-}
-
-static void slist_containee_foreach (GtsContainee * c,
-				     GtsFunc func, 
-				     gpointer data)
-{
-  GSList * i = GTS_SLIST_CONTAINEE (c)->containers;
-
-  while (i) {
-    GSList * next = i->next;
-    
-    (* func) (i->data, data);
-    i = next;
-  }
-}
-
-static gboolean slist_containee_is_contained (GtsContainee * i,
-					      GtsContainer * c)
-{
-  return g_slist_find (GTS_SLIST_CONTAINEE (i)->containers, c) ? TRUE : FALSE;
-}
-
-static void slist_containee_class_init (GtsSListContaineeClass * klass)
-{
-  GTS_CONTAINEE_CLASS (klass)->remove_container = 
-    slist_containee_remove_container;
-  GTS_CONTAINEE_CLASS (klass)->add_container = 
-    slist_containee_add_container;
-  GTS_CONTAINEE_CLASS (klass)->foreach = 
-    slist_containee_foreach;
-  GTS_CONTAINEE_CLASS (klass)->is_contained = 
-    slist_containee_is_contained;
-
-  GTS_OBJECT_CLASS (klass)->destroy = slist_containee_destroy;
-}
-
-static void slist_containee_init (GtsSListContainee * object)
-{
-  object->containers = NULL;
-}
-
-GtsSListContaineeClass * gts_slist_containee_class (void)
-{
-  static GtsSListContaineeClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo slist_containee_info = {
-      "GtsSListContainee",
-      sizeof (GtsSListContainee),
-      sizeof (GtsSListContaineeClass),
-      (GtsObjectClassInitFunc) slist_containee_class_init,
-      (GtsObjectInitFunc) slist_containee_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_containee_class ()),
-				  &slist_containee_info);
-  }
-
-  return klass;
-}
-
-/* GtsContainer */
-
-static void remove_container (GtsContainee * item, GtsContainer * c)
-{
-  if (GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->remove_container)
-    (* GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->remove_container) 
-      (item, c);
-}
-
-static void container_destroy (GtsObject * object)
-{
-  GtsContainer * c = GTS_CONTAINER (object);
-
-  gts_container_foreach (c, (GtsFunc) remove_container, c);
-
-  (* GTS_OBJECT_CLASS (gts_container_class ())->parent_class->destroy) 
-    (object);
-}
-
-static void container_add (GtsContainer * c, GtsContainee * item)
-{
-  if (GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->add_container)
-    (* GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->add_container)
-      (item, c);
-}
-
-static void container_remove (GtsContainer * c, GtsContainee * item)
-{
-  if (GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->remove_container)
-    (* GTS_CONTAINEE_CLASS (GTS_OBJECT (item)->klass)->remove_container)
-      (item, c);
-}
-
-static void container_clone_add (GtsContainee * item, GtsContainer * clone)
-{
-  gts_container_add (clone, item);
-}
-
-static void container_clone (GtsObject * clone, GtsObject * object)
-{
-  gts_object_init (clone, object->klass);
-  gts_container_foreach (GTS_CONTAINER (object), 
-			 (GtsFunc) container_clone_add, clone);
-}
-
-static void container_class_init (GtsContainerClass * klass)
-{
-  klass->add = container_add;
-  klass->remove = container_remove;
-  klass->foreach = NULL;
-  klass->size = NULL;
-
-  GTS_OBJECT_CLASS (klass)->destroy = container_destroy;
-  GTS_OBJECT_CLASS (klass)->clone = container_clone;
-}
-
-GtsContainerClass * gts_container_class (void)
-{
-  static GtsContainerClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo container_info = {
-      "GtsContainer",
-      sizeof (GtsContainer),
-      sizeof (GtsContainerClass),
-      (GtsObjectClassInitFunc) container_class_init,
-      (GtsObjectInitFunc) NULL,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = 
-      gts_object_class_new (GTS_OBJECT_CLASS (gts_slist_containee_class ()), 
-			    &container_info);
-  }
-
-  return klass;
-}
-
-GtsContainer * gts_container_new (GtsContainerClass * klass)
-{
-  GtsContainer * object;
-
-  object = GTS_CONTAINER (gts_object_new (GTS_OBJECT_CLASS (klass)));
-
-  return object;
-}
-
-void gts_container_add (GtsContainer * c,
-			GtsContainee * item)
-{
-  g_return_if_fail (c != NULL);
-  g_return_if_fail (item != NULL);
-
-  g_assert (GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->add);
-  (* GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->add) (c, item);
-}
-
-void gts_container_remove (GtsContainer * c,
-			   GtsContainee * item)
-{
-  g_return_if_fail (c != NULL);
-  g_return_if_fail (item != NULL);
-
-  g_assert (GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->remove);
-  (* GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->remove) (c, item);
-}
-
-void gts_container_foreach (GtsContainer * c,
-			    GtsFunc func,
-			    gpointer data)
-{
-  g_return_if_fail (c != NULL);
-  g_return_if_fail (func != NULL);
-
-  if (GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->foreach)
-    (* GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->foreach) (c, func, data);
-}
-
-guint gts_container_size (GtsContainer * c)
-{
-  g_return_val_if_fail (c != NULL, 0);
-
-  if (GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->size)
-    return (* GTS_CONTAINER_CLASS (GTS_OBJECT (c)->klass)->size) (c);
-  return 0;
-}
-
-/* GtsHashContainer */
-
-static void hash_container_destroy (GtsObject * object)
-{
-  GHashTable * items = GTS_HASH_CONTAINER (object)->items;
-
-  (* GTS_OBJECT_CLASS (gts_hash_container_class ())->parent_class->destroy) 
-    (object);
-
-  g_hash_table_destroy (items);
-}
-
-static void hash_container_add (GtsContainer * c, GtsContainee * item)
-{
-  g_return_if_fail (GTS_HASH_CONTAINER (c)->frozen == FALSE);
-
-  g_hash_table_insert (GTS_HASH_CONTAINER (c)->items, item, NULL);
-
-  (* GTS_CONTAINER_CLASS (GTS_OBJECT_CLASS (gts_hash_container_class ())->parent_class)->add) (c, item);
-}
-
-static void hash_container_remove (GtsContainer * c, GtsContainee * item)
-{
-  g_return_if_fail (GTS_HASH_CONTAINER (c)->frozen == FALSE);
-
-  g_hash_table_remove (GTS_HASH_CONTAINER (c)->items, item);
-
-  (* GTS_CONTAINER_CLASS (GTS_OBJECT_CLASS (gts_hash_container_class ())->parent_class)->remove) (c, item);
-}
-
-static void hash_foreach (GtsContainee * item, 
-			  gpointer item_data, 
-			  gpointer * info)
-{
-  (* ((GtsFunc) info[0])) (item, info[1]);
-}
-
-static void hash_container_foreach (GtsContainer * c, 
-				    GtsFunc func, 
-				    gpointer data)
-{
-  gpointer info[2];
-  
-  info[0] = func;
-  info[1] = data;
-  /* prevent removing or adding items */
-  GTS_HASH_CONTAINER (c)->frozen = TRUE;
-  g_hash_table_foreach (GTS_HASH_CONTAINER (c)->items, 
-			(GHFunc) hash_foreach, info);
-  GTS_HASH_CONTAINER (c)->frozen = FALSE;
-}
-
-static guint hash_container_size (GtsContainer * c)
-{
-  return g_hash_table_size (GTS_HASH_CONTAINER (c)->items);
-}
-
-static void hash_container_class_init (GtsHashContainerClass * klass)
-{
-  GTS_CONTAINER_CLASS (klass)->add = hash_container_add;
-  GTS_CONTAINER_CLASS (klass)->remove = hash_container_remove;
-  GTS_CONTAINER_CLASS (klass)->foreach = hash_container_foreach;
-  GTS_CONTAINER_CLASS (klass)->size = hash_container_size;
-
-  GTS_OBJECT_CLASS (klass)->destroy = hash_container_destroy;
-}
-
-static void hash_container_init (GtsHashContainer * object)
-{
-  object->items = g_hash_table_new (NULL, NULL);
-  object->frozen = FALSE;
-}
-
-GtsHashContainerClass * gts_hash_container_class (void)
-{
-  static GtsHashContainerClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo hash_container_info = {
-      "GtsHashContainer",
-      sizeof (GtsHashContainer),
-      sizeof (GtsHashContainerClass),
-      (GtsObjectClassInitFunc) hash_container_class_init,
-      (GtsObjectInitFunc) hash_container_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_container_class ()),
-				  &hash_container_info);
-  }
-
-  return klass;
-}
-
-/* GtsSListContainer */
-
-static void slist_container_destroy (GtsObject * object)
-{
-  GSList * items = GTS_SLIST_CONTAINER (object)->items;
-
-  (* GTS_OBJECT_CLASS (gts_slist_container_class ())->parent_class->destroy) 
-    (object);
-
-  g_slist_free (items);
-}
-
-static void slist_container_add (GtsContainer * c, GtsContainee * item)
-{
-  g_return_if_fail (GTS_SLIST_CONTAINER (c)->frozen == FALSE);
-
-  if (!g_slist_find (GTS_SLIST_CONTAINER (c)->items, item))
-    GTS_SLIST_CONTAINER (c)->items = 
-      g_slist_prepend (GTS_SLIST_CONTAINER (c)->items, item);
-
-  (* GTS_CONTAINER_CLASS (GTS_OBJECT_CLASS (gts_slist_container_class ())->parent_class)->add) (c, item);
-}
-
-static void slist_container_remove (GtsContainer * c, GtsContainee * item)
-{
-  g_return_if_fail (GTS_SLIST_CONTAINER (c)->frozen == FALSE);
-
-  GTS_SLIST_CONTAINER (c)->items = 
-      g_slist_remove (GTS_SLIST_CONTAINER (c)->items, item);
-
-  (* GTS_CONTAINER_CLASS (GTS_OBJECT_CLASS (gts_slist_container_class ())->parent_class)->remove) (c, item);
-}
-
-static void slist_container_foreach (GtsContainer * c, 
-				     GtsFunc func, 
-				     gpointer data)
-{
-  GSList * i;
-
-  i = GTS_SLIST_CONTAINER (c)->items;
-  while (i) {
-    GSList * next = i->next;
-
-    (* func) (i->data, data);
-    i = next;
-  }
-}
-
-static guint slist_container_size (GtsContainer * c)
-{
-  return g_slist_length (GTS_SLIST_CONTAINER (c)->items);
-}
-
-static void slist_container_class_init (GtsSListContainerClass * klass)
-{
-  GTS_CONTAINER_CLASS (klass)->add = slist_container_add;
-  GTS_CONTAINER_CLASS (klass)->remove = slist_container_remove;
-  GTS_CONTAINER_CLASS (klass)->foreach = slist_container_foreach;
-  GTS_CONTAINER_CLASS (klass)->size = slist_container_size;
-
-  GTS_OBJECT_CLASS (klass)->destroy = slist_container_destroy;
-}
-
-static void slist_container_init (GtsSListContainer * object)
-{
-  object->items = NULL;
-  object->frozen = FALSE;
-}
-
-GtsSListContainerClass * gts_slist_container_class (void)
-{
-  static GtsSListContainerClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo slist_container_info = {
-      "GtsSListContainer",
-      sizeof (GtsSListContainer),
-      sizeof (GtsSListContainerClass),
-      (GtsObjectClassInitFunc) slist_container_class_init,
-      (GtsObjectInitFunc) slist_container_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_container_class ()),
-				  &slist_container_info);
-  }
-
-  return klass;
-}
diff --git a/src/gts/curvature.c b/src/gts/curvature.c
deleted file mode 100644
index 70f6af2..0000000
--- a/src/gts/curvature.c
+++ /dev/null
@@ -1,621 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999-2002 Ray Jones, Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <math.h>
-#include "gts.h"
-
-static gboolean angle_obtuse (GtsVertex * v, GtsFace * f)
-{
-  GtsEdge * e = gts_triangle_edge_opposite (GTS_TRIANGLE (f), v);
-  GtsVector vec1, vec2;
-
-  gts_vector_init (vec1, GTS_POINT (v), GTS_POINT (GTS_SEGMENT (e)->v1));
-  gts_vector_init (vec2, GTS_POINT (v), GTS_POINT (GTS_SEGMENT (e)->v2));
-
-  return (gts_vector_scalar (vec1, vec2) < 0.0);
-}
-
-static gboolean triangle_obtuse (GtsVertex * v, GtsFace * f)
-{
-  GtsEdge * e = gts_triangle_edge_opposite (GTS_TRIANGLE (f), v);
-
-  return (angle_obtuse (v, f) ||
-          angle_obtuse (GTS_SEGMENT (e)->v1, f) ||
-          angle_obtuse (GTS_SEGMENT (e)->v2, f));
-} 
-
-static gdouble cotan (GtsVertex * vo, GtsVertex * v1, GtsVertex * v2)
-{
-  /* cf. Appendix B of [Meyer et al 2002] */
-  GtsVector u, v;
-  gdouble udotv, denom;
-
-  gts_vector_init (u, GTS_POINT (vo), GTS_POINT (v1));
-  gts_vector_init (v, GTS_POINT (vo), GTS_POINT (v2));
-
-  udotv = gts_vector_scalar (u, v);
-  denom = sqrt (gts_vector_scalar (u,u)*gts_vector_scalar (v,v) -
-		udotv*udotv);
-
-
-  /* denom can be zero if u==v.  Returning 0 is acceptable, based on
-   * the callers of this function below. */
-  if (denom == 0.0) return (0.0);
-
-  return (udotv/denom);
-}
-
-static gdouble angle_from_cotan (GtsVertex * vo, 
-				 GtsVertex * v1, GtsVertex * v2)
-{
-  /* cf. Appendix B and the caption of Table 1 from [Meyer et al 2002] */
-  GtsVector u, v;
-  gdouble udotv, denom;
-
-  gts_vector_init (u, GTS_POINT (vo), GTS_POINT (v1));
-  gts_vector_init (v, GTS_POINT (vo), GTS_POINT (v2));
-
-  udotv = gts_vector_scalar (u, v);
-  denom = sqrt (gts_vector_scalar (u,u)*gts_vector_scalar (v,v) 
-		- udotv*udotv);
-
-  /* Note: I assume this is what they mean by using atan2 (). -Ray Jones */
-
-  /* tan = denom/udotv = y/x (see man page for atan2) */
-  return (fabs (atan2 (denom, udotv)));
-}
-
-static gdouble region_area (GtsVertex * v, GtsFace * f)
-{
-  /* cf. Section 3.3 of [Meyer et al 2002] */
-  
-  if (gts_triangle_area (GTS_TRIANGLE (f)) == 0.0) return (0.0);
-
-  if (triangle_obtuse (v, f)) {
-    if (angle_obtuse (v, f))
-      return (gts_triangle_area (GTS_TRIANGLE (f))/2.0);
-    else
-      return (gts_triangle_area (GTS_TRIANGLE (f))/4.0);
-  } else {
-    GtsEdge * e = gts_triangle_edge_opposite (GTS_TRIANGLE (f), v);
-
-    return ((cotan (GTS_SEGMENT (e)->v1, v, GTS_SEGMENT (e)->v2)* 
-             gts_point_distance2 (GTS_POINT (v), 
-				  GTS_POINT (GTS_SEGMENT (e)->v2)) +
-             cotan (GTS_SEGMENT (e)->v2, v, GTS_SEGMENT (e)->v1)* 
-             gts_point_distance2 (GTS_POINT (v), 
-                                  GTS_POINT (GTS_SEGMENT (e)->v1)))
-            /8.0);
-  }
-}
-
-/** 
- * gts_vertex_mean_curvature_normal:
- * @v: a #GtsVertex.  
- * @s: a #GtsSurface.
- * @Kh: the Mean Curvature Normal at @v.
- *
- * Computes the Discrete Mean Curvature Normal approximation at @v.
- * The mean curvature at @v is half the magnitude of the vector @Kh.
- *
- * Note: the normal computed is not unit length, and may point either
- * into or out of the surface, depending on the curvature at @v.  It
- * is the responsibility of the caller of the function to use the mean
- * curvature normal appropriately.
- *
- * This approximation is from the paper:
- * Discrete Differential-Geometry Operators for Triangulated 2-Manifolds
- * Mark Meyer, Mathieu Desbrun, Peter Schroder, Alan H. Barr
- * VisMath '02, Berlin (Germany) 
- * http://www-grail.usc.edu/pubs.html
- *
- * Returns: %TRUE if the operator could be evaluated, %FALSE if the
- * evaluation failed for some reason (@v is boundary or is the
- * endpoint of a non-manifold edge.)
- */
-gboolean gts_vertex_mean_curvature_normal (GtsVertex * v, GtsSurface * s, 
-                                           GtsVector Kh)
-{
-  GSList * faces, * edges, * i;
-  gdouble area = 0.0;
-
-  g_return_val_if_fail (v != NULL, FALSE);
-  g_return_val_if_fail (s != NULL, FALSE);
-
-  /* this operator is not defined for boundary edges */
-  if (gts_vertex_is_boundary (v, s)) return (FALSE);
-    
-  faces = gts_vertex_faces (v, s, NULL);
-  g_return_val_if_fail (faces != NULL, FALSE);
-
-  edges = gts_vertex_fan_oriented (v, s);
-  if (edges == NULL) {
-    g_slist_free (faces);
-    return (FALSE);
-  }
-
-  i = faces;
-  while (i) {
-    GtsFace * f = i->data;
-
-    area += region_area (v, f);
-    i = i->next;
-  } 
-  g_slist_free (faces);
-
-  Kh[0] = Kh[1] = Kh[2] = 0.0;
-
-  i = edges;
-  while (i) {
-    GtsEdge * e = i->data;
-    GtsVertex * v1 = GTS_SEGMENT (e)->v1;
-    GtsVertex * v2 = GTS_SEGMENT (e)->v2;
-    gdouble temp;
-
-    temp = cotan (v1, v, v2);
-    Kh[0] += temp*(GTS_POINT (v2)->x - GTS_POINT (v)->x);
-    Kh[1] += temp*(GTS_POINT (v2)->y - GTS_POINT (v)->y);
-    Kh[2] += temp*(GTS_POINT (v2)->z - GTS_POINT (v)->z);
-
-    temp = cotan (v2, v, v1);
-    Kh[0] += temp*(GTS_POINT (v1)->x - GTS_POINT (v)->x);
-    Kh[1] += temp*(GTS_POINT (v1)->y - GTS_POINT (v)->y);
-    Kh[2] += temp*(GTS_POINT (v1)->z - GTS_POINT (v)->z);
-
-    i = i->next;
-  }
-  g_slist_free (edges);
-
-  if (area > 0.0) {
-    Kh[0] /= 2*area;
-    Kh[1] /= 2*area;
-    Kh[2] /= 2*area;
-  } else {
-    return (FALSE);
-  }
- 
-  return TRUE;
-}
-
-/** 
- * gts_vertex_gaussian_curvature:
- * @v: a #GtsVertex.  
- * @s: a #GtsSurface.
- * @Kg: the Discrete Gaussian Curvature approximation at @v.
- *
- * Computes the Discrete Gaussian Curvature approximation at @v.
- *
- * This approximation is from the paper:
- * Discrete Differential-Geometry Operators for Triangulated 2-Manifolds
- * Mark Meyer, Mathieu Desbrun, Peter Schroder, Alan H. Barr
- * VisMath '02, Berlin (Germany) 
- * http://www-grail.usc.edu/pubs.html
- *
- * Returns: %TRUE if the operator could be evaluated, %FALSE if the
- * evaluation failed for some reason (@v is boundary or is the
- * endpoint of a non-manifold edge.)
- */
-gboolean gts_vertex_gaussian_curvature (GtsVertex * v, GtsSurface * s, 
-                                        gdouble * Kg)
-{
-  GSList * faces, * edges, * i;
-  gdouble area = 0.0;
-  gdouble angle_sum = 0.0;
-
-  g_return_val_if_fail (v != NULL, FALSE);
-  g_return_val_if_fail (s != NULL, FALSE);
-  g_return_val_if_fail (Kg != NULL, FALSE);
-
-  /* this operator is not defined for boundary edges */
-  if (gts_vertex_is_boundary (v, s)) return (FALSE);
-    
-  faces = gts_vertex_faces (v, s, NULL);
-  g_return_val_if_fail (faces != NULL, FALSE);
-
-  edges = gts_vertex_fan_oriented (v, s);
-  if (edges == NULL) {
-    g_slist_free (faces);
-    return (FALSE);
-  }
-
-  i = faces;
-  while (i) {
-    GtsFace * f = i->data;
-
-    area += region_area (v, f);
-    i = i->next;
-  } 
-  g_slist_free (faces);
-
-  i = edges;
-  while (i) {
-    GtsEdge * e = i->data;
-    GtsVertex * v1 = GTS_SEGMENT (e)->v1;
-    GtsVertex * v2 = GTS_SEGMENT (e)->v2;
-
-    angle_sum += angle_from_cotan (v, v1, v2);
-    i = i->next;
-  }
-  g_slist_free (edges);
-
-  *Kg = (2.0*M_PI - angle_sum)/area;
- 
-  return TRUE;
-}
-
-/** 
- * gts_vertex_principal_curvatures:
- * @Kh: mean curvature.
- * @Kg: Gaussian curvature.
- * @K1: first principal curvature.
- * @K2: second principal curvature.
- *
- * Computes the principal curvatures at a point given the mean and
- * Gaussian curvatures at that point.  
- *
- * The mean curvature can be computed as one-half the magnitude of the
- * vector computed by gts_vertex_mean_curvature_normal().
- *
- * The Gaussian curvature can be computed with
- * gts_vertex_gaussian_curvature().
- */
-void gts_vertex_principal_curvatures (gdouble Kh, gdouble Kg, 
-				      gdouble * K1, gdouble * K2)
-{
-  gdouble temp = Kh*Kh - Kg;
-
-  g_return_if_fail (K1 != NULL);
-  g_return_if_fail (K2 != NULL);
-
-  if (temp < 0.0) temp = 0.0;
-  temp = sqrt (temp);
-  *K1 = Kh + temp;
-  *K2 = Kh - temp;
-}
-
-/* from Maple */
-static void linsolve (gdouble m11, gdouble m12, gdouble b1,
-		      gdouble m21, gdouble m22, gdouble b2,
-		      gdouble * x1, gdouble * x2)
-{
-  gdouble temp;
-
-  temp = 1.0 / (m21*m12 - m11*m22);
-  *x1 = (m12*b2 - m22*b1)*temp;
-  *x2 = (m11*b2 - m21*b1)*temp;
-}
-                
-/* from Maple - largest eigenvector of [a b; b c] */
-static void eigenvector (gdouble a, gdouble b, gdouble c,
-			 GtsVector e)
-{
-  if (b == 0.0) {
-    e[0] = 0.0;
-  } else {
-    e[0] = -(c - a - sqrt (c*c - 2*a*c + a*a + 4*b*b))/(2*b);
-  }
-  e[1] = 1.0;
-  e[2] = 0.0;
-}
-
-/** 
- * gts_vertex_principal_directions:
- * @v: a #GtsVertex.  
- * @s: a #GtsSurface.
- * @Kh: mean curvature normal (a #GtsVector).
- * @Kg: Gaussian curvature (a gdouble).
- * @e1: first principal curvature direction (direction of largest curvature).
- * @e2: second principal curvature direction.
- *
- * Computes the principal curvature directions at a point given @Kh
- * and @Kg, the mean curvature normal and Gaussian curvatures at that
- * point, computed with gts_vertex_mean_curvature_normal() and
- * gts_vertex_gaussian_curvature(), respectively. 
- *
- * Note that this computation is very approximate and tends to be
- * unstable.  Smoothing of the surface or the principal directions may
- * be necessary to achieve reasonable results.  
- */
-void gts_vertex_principal_directions (GtsVertex * v, GtsSurface * s,
-                                      GtsVector Kh, gdouble Kg,
-				      GtsVector e1, GtsVector e2)
-{
-  GtsVector N;
-  gdouble normKh;
-  GSList * i, * j;
-  GtsVector basis1, basis2, d, eig;
-  gdouble ve2, vdotN;
-  gdouble aterm_da, bterm_da, cterm_da, const_da;
-  gdouble aterm_db, bterm_db, cterm_db, const_db;
-  gdouble a, b, c;
-  gdouble K1, K2;
-  gdouble *weights, *kappas, *d1s, *d2s;
-  gint edge_count;
-  gdouble err_e1, err_e2;
-  int e;
-
-  /* compute unit normal */
-  normKh = sqrt (gts_vector_scalar (Kh, Kh));
-
-  if (normKh > 0.0) {
-    N[0] = Kh[0] / normKh;
-    N[1] = Kh[1] / normKh;
-    N[2] = Kh[2] / normKh;
-  } else {
-    /* This vertex is a point of zero mean curvature (flat or saddle
-     * point).  Compute a normal by averaging the adjacent triangles
-     */
-    N[0] = N[1] = N[2] = 0.0;
-    i = gts_vertex_faces (v, s, NULL);
-    while (i) {
-      gdouble x, y, z;
-      gts_triangle_normal (GTS_TRIANGLE ((GtsFace *) i->data),
-                           &x, &y, &z);
-      N[0] += x;
-      N[1] += y;
-      N[2] += z;
-
-      i = i->next;
-    }
-    g_return_if_fail (gts_vector_norm (N) > 0.0);
-    gts_vector_normalize (N);
-  }
-    
-
-  /* construct a basis from N: */
-  /* set basis1 to any component not the largest of N */
-  basis1[0] =  basis1[1] =  basis1[2] = 0.0;
-  if (fabs (N[0]) > fabs (N[1]))
-    basis1[1] = 1.0;
-  else
-    basis1[0] = 1.0;
-    
-  /* make basis2 orthogonal to N */
-  gts_vector_cross (basis2, N, basis1);
-  gts_vector_normalize (basis2);
-
-  /* make basis1 orthogonal to N and basis2 */
-  gts_vector_cross (basis1, N, basis2);
-  gts_vector_normalize (basis1);
-  
-  aterm_da = bterm_da = cterm_da = const_da = 0.0;
-  aterm_db = bterm_db = cterm_db = const_db = 0.0;
-
-  weights = g_malloc (sizeof (gdouble)*g_slist_length (v->segments));
-  kappas = g_malloc (sizeof (gdouble)*g_slist_length (v->segments));
-  d1s = g_malloc (sizeof (gdouble)*g_slist_length (v->segments));
-  d2s = g_malloc (sizeof (gdouble)*g_slist_length (v->segments));
-  edge_count = 0;
-
-  i = v->segments;
-  while (i) {
-    GtsEdge * e;
-    GtsFace * f1, * f2;
-    gdouble weight, kappa, d1, d2;
-    GtsVector vec_edge;
-
-    if (! GTS_IS_EDGE (i->data)) {
-      i = i->next;
-      continue;
-    }
-
-    e = i->data;
-
-    /* since this vertex passed the tests in
-     * gts_vertex_mean_curvature_normal(), this should be true. */
-    g_assert (gts_edge_face_number (e, s) == 2);
-
-    /* identify the two triangles bordering e in s */
-    f1 = f2 = NULL;
-    j = e->triangles;
-    while (j) {
-      if ((! GTS_IS_FACE (j->data)) || 
-          (! gts_face_has_parent_surface (GTS_FACE (j->data), s))) {
-        j = j->next;
-        continue;
-      }
-      if (f1 == NULL)
-        f1 = GTS_FACE (j->data);
-      else {
-        f2 = GTS_FACE (j->data);
-        break;
-      }
-      j = j->next;
-    }
-    g_assert (f2 != NULL);
-
-    /* We are solving for the values of the curvature tensor 
-     *     B = [ a b ; b c ].  
-     * The computations here are from section 5 of [Meyer et al 2002].  
-     *
-     * The first step is to calculate the linear equations governing
-     * the values of (a,b,c).  These can be computed by setting the
-     * derivatives of the error E to zero (section 5.3).
-     * 
-     * Since a + c = norm(Kh), we only compute the linear equations
-     * for dE/da and dE/db.  (NB: [Meyer et al 2002] has the
-     * equation a + b = norm(Kh), but I'm almost positive this is
-     * incorrect.)
-     *
-     * Note that the w_ij (defined in section 5.2) are all scaled by
-     * (1/8*A_mixed).  We drop this uniform scale factor because the
-     * solution of the linear equations doesn't rely on it.
-     *
-     * The terms of the linear equations are xterm_dy with x in
-     * {a,b,c} and y in {a,b}.  There are also const_dy terms that are
-     * the constant factors in the equations.  
-     */
-
-    /* find the vector from v along edge e */
-    gts_vector_init (vec_edge, GTS_POINT (v), 
-                     GTS_POINT ((GTS_SEGMENT (e)->v1 == v) ? 
-                                GTS_SEGMENT (e)->v2 : GTS_SEGMENT (e)->v1));
-    ve2 = gts_vector_scalar (vec_edge, vec_edge);
-    vdotN = gts_vector_scalar (vec_edge, N);
-
-    /* section 5.2 - There is a typo in the computation of kappa.  The
-     * edges should be x_j-x_i.
-     */
-    kappa = 2.0 * vdotN / ve2;
-
-    /* section 5.2 */
-
-    /* I don't like performing a minimization where some of the
-     * weights can be negative (as can be the case if f1 or f2 are
-     * obtuse).  To ensure all-positive weights, we check for
-     * obtuseness and use values similar to those in region_area(). */
-    weight = 0.0;
-    if (! triangle_obtuse(v, f1)) {
-      weight += ve2 * 
-        cotan (gts_triangle_vertex_opposite (GTS_TRIANGLE (f1), e), 
-               GTS_SEGMENT (e)->v1, GTS_SEGMENT (e)->v2) / 8.0;
-    } else {
-      if (angle_obtuse (v, f1)) {
-        weight += ve2 * gts_triangle_area (GTS_TRIANGLE (f1)) / 4.0;
-      } else {
-        weight += ve2 * gts_triangle_area (GTS_TRIANGLE (f1)) / 8.0;
-      }
-    }
-
-    if (! triangle_obtuse(v, f2)) {
-      weight += ve2 * 
-        cotan (gts_triangle_vertex_opposite (GTS_TRIANGLE (f2), e), 
-               GTS_SEGMENT (e)->v1, GTS_SEGMENT (e)->v2) / 8.0;
-    } else {
-      if (angle_obtuse (v, f2)) {
-        weight += ve2 * gts_triangle_area (GTS_TRIANGLE (f2)) / 4.0;
-      } else {
-        weight += ve2 * gts_triangle_area (GTS_TRIANGLE (f2)) / 8.0;
-      }
-    }
-
-    /* projection of edge perpendicular to N (section 5.3) */
-    d[0] = vec_edge[0] - vdotN * N[0];
-    d[1] = vec_edge[1] - vdotN * N[1];
-    d[2] = vec_edge[2] - vdotN * N[2];
-    gts_vector_normalize (d);
-    
-    /* not explicit in the paper, but necessary.  Move d to 2D basis. */
-    d1 = gts_vector_scalar (d, basis1);
-    d2 = gts_vector_scalar (d, basis2);
-
-    /* store off the curvature, direction of edge, and weights for later use */
-    weights[edge_count] = weight;
-    kappas[edge_count] = kappa;
-    d1s[edge_count] = d1;
-    d2s[edge_count] = d2;
-    edge_count++;
-
-    /* Finally, update the linear equations */
-    aterm_da += weight * d1 * d1 * d1 * d1;
-    bterm_da += weight * d1 * d1 * 2 * d1 * d2;
-    cterm_da += weight * d1 * d1 * d2 * d2;
-    const_da += weight * d1 * d1 * (- kappa);
-
-    aterm_db += weight * d1 * d2 * d1 * d1;
-    bterm_db += weight * d1 * d2 * 2 * d1 * d2;
-    cterm_db += weight * d1 * d2 * d2 * d2;
-    const_db += weight * d1 * d2 * (- kappa);
-
-    i = i->next;
-  }
-
-  /* now use the identity (Section 5.3) a + c = |Kh| = 2 * kappa_h */
-  aterm_da -= cterm_da;
-  const_da += cterm_da * normKh;
-
-  aterm_db -= cterm_db;
-  const_db += cterm_db * normKh;
-  
-  /* check for solvability of the linear system */
-  if (((aterm_da * bterm_db - aterm_db * bterm_da) != 0.0) &&
-      ((const_da != 0.0) || (const_db != 0.0))) {
-    linsolve (aterm_da, bterm_da, -const_da,
-              aterm_db, bterm_db, -const_db,
-              &a, &b);
-
-    c = normKh - a;
-
-    eigenvector (a, b, c, eig);
-  } else {
-    /* region of v is planar */
-    eig[0] = 1.0;
-    eig[1] = 0.0;
-  }
-
-  /* Although the eigenvectors of B are good estimates of the
-   * principal directions, it seems that which one is attached to
-   * which curvature direction is a bit arbitrary.  This may be a bug
-   * in my implementation, or just a side-effect of the inaccuracy of
-   * B due to the discrete nature of the sampling.
-   *
-   * To overcome this behavior, we'll evaluate which assignment best
-   * matches the given eigenvectors by comparing the curvature
-   * estimates computed above and the curvatures calculated from the
-   * discrete differential operators.  */
-
-  gts_vertex_principal_curvatures (0.5 * normKh, Kg, &K1, &K2);
-  
-  err_e1 = err_e2 = 0.0;
-  /* loop through the values previously saved */
-  for (e = 0; e < edge_count; e++) {
-    gdouble weight, kappa, d1, d2;
-    gdouble temp1, temp2;
-    gdouble delta;
-
-    weight = weights[e];
-    kappa = kappas[e];
-    d1 = d1s[e];
-    d2 = d2s[e];
-
-    temp1 = fabs (eig[0] * d1 + eig[1] * d2);
-    temp1 = temp1 * temp1;
-    temp2 = fabs (eig[1] * d1 - eig[0] * d2);
-    temp2 = temp2 * temp2;
-
-    /* err_e1 is for K1 associated with e1 */
-    delta = K1 * temp1 + K2 * temp2 - kappa;
-    err_e1 += weight * delta * delta;
-
-    /* err_e2 is for K1 associated with e2 */
-    delta = K2 * temp1 + K1 * temp2 - kappa;
-    err_e2 += weight * delta * delta;
-  }
-  g_free (weights);
-  g_free (kappas);
-  g_free (d1s);
-  g_free (d2s);
-
-  /* rotate eig by a right angle if that would decrease the error */
-  if (err_e2 < err_e1) {
-    gdouble temp = eig[0];
-
-    eig[0] = eig[1];
-    eig[1] = -temp;
-  }
-
-  e1[0] = eig[0] * basis1[0] + eig[1] * basis2[0];
-  e1[1] = eig[0] * basis1[1] + eig[1] * basis2[1];
-  e1[2] = eig[0] * basis1[2] + eig[1] * basis2[2];
-  gts_vector_normalize (e1);
-
-  /* make N,e1,e2 a right handed coordinate sytem */
-  gts_vector_cross (e2, N, e1);
-  gts_vector_normalize (e2);
-}
diff --git a/src/gts/edge.c b/src/gts/edge.c
deleted file mode 100644
index fde7d87..0000000
--- a/src/gts/edge.c
+++ /dev/null
@@ -1,585 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include "gts.h"
-
-gboolean gts_allow_floating_edges = FALSE;
-
-static void edge_destroy (GtsObject * object)
-{
-  GtsEdge * edge = GTS_EDGE (object);
-  GSList * i;
-
-  i = edge->triangles;
-  while (i) {
-    GSList * next = i->next;
-    gts_object_destroy (i->data);
-    i = next;
-  }
-  g_assert (edge->triangles == NULL);
-
-  (* GTS_OBJECT_CLASS (gts_edge_class ())->parent_class->destroy) (object);
-}
-
-static void edge_clone (GtsObject * clone, GtsObject * object)
-{
-  (* GTS_OBJECT_CLASS (gts_edge_class ())->parent_class->clone) (clone,
-								 object);
-  GTS_SEGMENT (clone)->v1 = GTS_SEGMENT (clone)->v2 = NULL;
-  GTS_EDGE (clone)->triangles = NULL;
-}
-
-static void edge_class_init (GtsObjectClass * klass)
-{
-  klass->clone = edge_clone;
-  klass->destroy = edge_destroy;
-}
-
-static void edge_init (GtsEdge * edge)
-{
-  edge->triangles = NULL;
-}
-
-/**
- * gts_edge_class:
- *
- * Returns: the #GtsEdgeClass.
- */
-GtsEdgeClass * gts_edge_class (void)
-{
-  static GtsEdgeClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo edge_info = {
-      "GtsEdge",
-      sizeof (GtsEdge),
-      sizeof (GtsEdgeClass),
-      (GtsObjectClassInitFunc) edge_class_init,
-      (GtsObjectInitFunc) edge_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_segment_class ()), 
-				  &edge_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_edge_new:
- * @klass: a #GtsEdgeClass.
- * @v1: a #GtsVertex.
- * @v2: a #GtsVertex.
- *
- * Returns: a new #GtsEdge linking @v1 and @v2.
- */
-GtsEdge * gts_edge_new (GtsEdgeClass * klass,
-			GtsVertex * v1, GtsVertex * v2)
-{
-  return GTS_EDGE (gts_segment_new (GTS_SEGMENT_CLASS (klass), v1, v2));
-}
-
-void gts_edge_remove(GtsEdge *edge) 
-{
-  edge->segment.v1->segments = g_slist_remove(edge->segment.v1->segments, &edge->segment);
-  edge->segment.v2->segments = g_slist_remove(edge->segment.v2->segments, &edge->segment);
-  edge_destroy(GTS_OBJECT (edge));
-}
-
-/**
- * gts_edge_replace:
- * @e: a #GtsEdge.
- * @with: a #GtsEdge.
- *
- * Replaces @e with @with. For each triangle which uses @e as an
- * edge, @e is replaced with @with. The @with->triangles list is
- * updated appropriately and the @e->triangles list is freed and set
- * to %NULL.
- */
-void gts_edge_replace (GtsEdge * e, GtsEdge * with)
-{
-  GSList * i;
-
-  g_return_if_fail (e != NULL && with != NULL && e != with);
-
-  i = e->triangles;
-  while (i) {
-    GtsTriangle * t = i->data;
-    if (t->e1 == e) t->e1 = with;
-    if (t->e2 == e) t->e2 = with;
-    if (t->e3 == e) t->e3 = with;
-    if (!g_slist_find (with->triangles, t))
-      with->triangles = g_slist_prepend (with->triangles, t);
-    i = i->next;
-  }
-  g_slist_free (e->triangles);
-  e->triangles = NULL;
-}
-
-/**
- * gts_edge_has_parent_surface:
- * @e: a #GtsEdge.
- * @surface: a #GtsSurface.
- * 
- * Returns: a #GtsFace of @surface having @e as an edge, %NULL otherwise.
- */
-GtsFace * gts_edge_has_parent_surface (GtsEdge * e, GtsSurface * surface)
-{
-  GSList * i;
-
-  g_return_val_if_fail (e != NULL, NULL);
-
-  i = e->triangles;
-  while (i) {
-    if (GTS_IS_FACE (i->data) && 
-	gts_face_has_parent_surface (i->data, surface))
-      return i->data;
-    i = i->next;
-  }
-  return NULL;
-}
-
-/**
- * gts_edge_has_any_parent_surface:
- * @e: a #GtsEdge.
- * 
- * Returns: %NULL if @e is not an edge of any triangle or if all the
- * faces having @e has an edge do not belong to any surface,
- * a #GtsFace belonging to a surface and having @e as an edge.
- */
-GtsFace * gts_edge_has_any_parent_surface (GtsEdge * e)
-{
-  GSList * i;
-
-  g_return_val_if_fail (e != NULL, NULL);
-
-  i = e->triangles;
-  while (i) {
-    GtsTriangle * t = i->data;
-    if (GTS_IS_FACE (t) && GTS_FACE (t)->surfaces != NULL)
-      return GTS_FACE (t);
-    i = i->next;
-  }
-  return NULL;
-}
-
-/**
- * gts_edge_is_boundary:
- * @e: a #GtsEdge.
- * @surface: a #GtsSurface or %NULL.
- * 
- * Returns: the unique #GtsFace (which belongs to @surface) and which
- * has @e as an edge (i.e. @e is a boundary edge (of @surface)) or %NULL 
- * if there is more than one or no faces (belonging to @surface) and
- * with @e as an edge.
- */
-GtsFace * gts_edge_is_boundary (GtsEdge * e, GtsSurface * surface)
-{
-  GSList * i;
-  GtsFace * f = NULL;
-  
-  g_return_val_if_fail (e != NULL, NULL);
-  
-  i = e->triangles;
-  while (i) {
-    if (GTS_IS_FACE (i->data)) {
-      if (!surface || gts_face_has_parent_surface (i->data, surface)) {
-	if (f != NULL)
-	  return NULL;
-	f = i->data;
-      }
-    }
-    i = i->next;    
-  }
-  return f;
-}
-
-/**
- * gts_edges_from_vertices:
- * @vertices: a list of #GtsVertex.
- * @parent: a #GtsSurface.
- * 
- * Returns: a list of unique #GtsEdge which have one of their vertices in 
- * @vertices and are used by a face of @parent. 
- */
-GSList * gts_edges_from_vertices (GSList * vertices, GtsSurface * parent)
-{
-  GHashTable * hash;
-  GSList * edges = NULL, * i;
-
-  g_return_val_if_fail (parent != NULL, NULL);
-  
-  hash = g_hash_table_new (NULL, NULL);
-  i = vertices;
-  while (i) {
-    GSList * j = GTS_VERTEX (i->data)->segments;
-    while (j) {
-      GtsSegment * s = j->data;
-      if (GTS_IS_EDGE (s) &&
-	  gts_edge_has_parent_surface (GTS_EDGE (s), parent) && 
-	  g_hash_table_lookup (hash, s) == NULL) {
-	edges = g_slist_prepend (edges, s);
-	g_hash_table_insert (hash, s, i);
-      }
-      j = j->next;
-    }
-    i = i->next;
-  }
-  g_hash_table_destroy (hash);
-  return edges;
-}
-
-/**
- * gts_edge_face_number:
- * @e: a #GtsEdge.
- * @s: a #GtsSurface.
- *
- * Returns: the number of faces using @e and belonging to @s.
- */
-guint gts_edge_face_number (GtsEdge * e, GtsSurface * s)
-{
-  GSList * i;
-  guint nt = 0;
-
-  g_return_val_if_fail (e != NULL, 0);
-  g_return_val_if_fail (s != NULL, 0);
-
-  i = e->triangles;
-  while (i) {
-    if (GTS_IS_FACE (i->data) && 
-	gts_face_has_parent_surface (GTS_FACE (i->data), s))
-      nt++;
-    i = i->next;
-  }
-  return nt;
-}
-
-/**
- * gts_edge_is_duplicate:
- * @e: a #GtsEdge.
- *
- * Returns: the first #GtsEdge different from @e which shares the
- * same endpoints or %NULL if there is none.
- */
-GtsEdge * gts_edge_is_duplicate (GtsEdge * e)
-{
-  GSList * i;
-  GtsVertex * v2;
-
-  g_return_val_if_fail (e != NULL, NULL);
-
-  v2 = GTS_SEGMENT (e)->v2;
-  i = GTS_SEGMENT (e)->v1->segments;
-  if (GTS_SEGMENT (e)->v1 == v2) /* e is degenerate: special treatment */
-    while (i) {
-      GtsSegment * s = i->data;
-      if (s != GTS_SEGMENT (e) &&
-	  GTS_IS_EDGE (s) && 
-	  s->v1 == v2 && s->v2 == v2)
-	return GTS_EDGE (s);
-      i = i->next;
-    }
-  else /* e is not degenerate */
-    while (i) {
-      GtsSegment * s = i->data;
-      if (s != GTS_SEGMENT (e) &&
-	  GTS_IS_EDGE (s) && 
-	  (s->v1 == v2 || s->v2 == v2))
-	return GTS_EDGE (s);
-      i = i->next;
-    }
-  return NULL;
-}
-
-/**
- * gts_edges_merge:
- * @edges: a list of #GtsEdge.
- *
- * For each edge in @edges check if it is duplicated (as
- * returned by gts_edge_is_duplicate()). If it is replace it by its
- * duplicate, destroy it and remove it from the list.
- *
- * Returns: the updated @edges list.
- */
-GList * gts_edges_merge (GList * edges)
-{
-  GList * i = edges;
-
-  /* we want to control edge destruction */
-  gts_allow_floating_edges = TRUE;
-  while (i) {
-    GtsEdge * e = i->data;
-    GtsEdge * de = gts_edge_is_duplicate (e);
-    if (de) {
-      GList * next = i->next;
-      edges = g_list_remove_link (edges, i);
-      g_list_free_1 (i);
-      i = next;
-      gts_edge_replace (e, de);
-      gts_object_destroy (GTS_OBJECT (e));
-    }
-    else
-      i = i->next;
-  }
-  gts_allow_floating_edges = FALSE;;
-
-  return edges;
-}
-
-static void triangle_vertices_edges (GtsTriangle * t, 
-				     GtsEdge * e,
-				     GtsVertex ** v,
-				     GtsEdge ** ee1,
-				     GtsEdge ** ee2)
-{
-  GtsEdge * e1 = t->e1, * e2 = t->e2, * e3 = t->e3;
-  GtsVertex * v1 = GTS_SEGMENT (e)->v1;
-
-  if (e1 == e)        e1 = e3;
-  else if (e2 == e)   e2 = e3;
-  else                g_assert (e3 == e);
-
-  if (GTS_SEGMENT (e2)->v1 == v1 || GTS_SEGMENT (e2)->v2 == v1) {
-    e3 = e1; e1 = e2; e2 = e3;
-  }
-  if (GTS_SEGMENT (e1)->v1 == v1)
-    *v = GTS_SEGMENT (e1)->v2;
-  else
-    *v = GTS_SEGMENT (e1)->v1;
-  *ee1 = e1;
-  *ee2 = e2;
-}
-
-/**
- * gts_edge_belongs_to_tetrahedron:
- * @e: a #GtsEdge.
- *
- * Returns: %TRUE if @e is used by faces forming a tetrahedron, %FALSE
- * otherwise.
- */
-gboolean gts_edge_belongs_to_tetrahedron (GtsEdge * e)
-{
-  GSList * i;
-  GtsVertex * v1, * v2;
-
-  g_return_val_if_fail (e != NULL, FALSE);
-
-  v1 = GTS_SEGMENT (e)->v1;
-  v2 = GTS_SEGMENT (e)->v2;
-  i = e->triangles;
-  while (i) {
-    GtsEdge * e1, * e2;
-    GtsVertex * vt1;
-    GSList * j = i->next;
-    triangle_vertices_edges (i->data, e, &vt1, &e1, &e2);
-    while (j) {      
-      GtsSegment * s5;
-      GtsEdge * e3, * e4;
-      GtsVertex * vt2;
-
-      triangle_vertices_edges (j->data, e, &vt2, &e3, &e4);
-      s5 = gts_vertices_are_connected (vt1, vt2);
-      if (GTS_IS_EDGE (s5) &&
-	  gts_triangle_use_edges (e1, e3, GTS_EDGE (s5)) &&
-	  gts_triangle_use_edges (e2, e4, GTS_EDGE (s5)))
-	return TRUE;
-      j = j->next;
-    }
-    i = i->next;
-  }
-
-  return FALSE;
-}
-
-#define edge_use_vertex(e, v) (GTS_SEGMENT(e)->v1 == v ||\
-			       GTS_SEGMENT(e)->v2 == v)
-
-static GtsEdge * next_edge (GtsTriangle * t,
-			    GtsEdge * e1,
-			    GtsEdge * e)
-{
-  GtsVertex * v1 = GTS_SEGMENT (e)->v1;
-  GtsVertex * v2 = GTS_SEGMENT (e)->v2;
-  
-  if (t->e1 != e1 && t->e1 != e && 
-      (edge_use_vertex (t->e1, v1) || edge_use_vertex (t->e1, v2)))
-    return t->e1;
-  else if (t->e2 != e1 && t->e2 != e && 
-	   (edge_use_vertex (t->e2, v1) || edge_use_vertex (t->e2, v2)))
-    return t->e2;
-  else if (t->e3 != e1 && t->e3 != e && 
-	   (edge_use_vertex (t->e3, v1) || edge_use_vertex (t->e3, v2)))
-    return t->e3;
-  g_assert_not_reached ();
-  return NULL;
-}
-
-static void triangle_next (GtsEdge * e1, GtsEdge * e)
-{
-  GSList * i;
-
-  i = e1->triangles;
-  while (i) {
-    GtsTriangle * t = i->data;
-    if (GTS_OBJECT (t)->reserved) {
-      GTS_OBJECT (t)->reserved = NULL;
-      triangle_next (next_edge (t, e1, e), e);
-    }
-    i = i->next;
-  }
-}
-
-/** 
- * gts_edge_is_contact: 
- * @e: a #GtsEdge.  
- *
- * Returns: the number of sets of connected triangles sharing @e as a
- * contact edge.  
- */
-guint gts_edge_is_contact (GtsEdge * e)
-{
-  GSList * i, * triangles;
-  guint ncomponent = 0;
-
-  g_return_val_if_fail (e != NULL, 0);
-
-  triangles = gts_vertex_triangles (GTS_SEGMENT (e)->v1, NULL);
-  i = triangles = gts_vertex_triangles (GTS_SEGMENT (e)->v2, triangles);
-  while (i) {
-    GTS_OBJECT (i->data)->reserved = i;
-    i = i->next;
-  }
-
-  i = e->triangles;
-  while (i) {
-    GtsTriangle * t = i->data;
-    if (GTS_OBJECT (t)->reserved) {
-      GtsEdge * e1;
-      GTS_OBJECT (t)->reserved = NULL;
-      e1 = next_edge (t, NULL, e);
-      triangle_next (e1, e);
-      triangle_next (next_edge (t, e1, e), e);
-      ncomponent++;
-    }
-    i = i->next;
-  }
-   
-  g_slist_foreach (triangles, (GFunc) gts_object_reset_reserved, NULL);
-  g_slist_free (triangles);
-
-  return ncomponent;
-}
-
-/**
- * gts_edge_swap:
- * @e: a #GtsEdge.
- * @s: a #GtsSurface.
- *
- * Performs an "edge swap" on the two triangles sharing @e and
- * belonging to @s.
- */
-void gts_edge_swap (GtsEdge * e, GtsSurface * s)
-{
-  GtsTriangle * t1 = NULL, * t2 = NULL, * t;
-  GtsFace * f;
-  GSList * i;
-  GtsVertex * v1, * v2, * v3, * v4, * v5, * v6;
-  GtsEdge * e1, * e2, * e3, * e4;
-  GtsSegment * v3v6;
-
-  g_return_if_fail (e != NULL);
-  g_return_if_fail (s != NULL);
-
-  i = e->triangles;
-  while (i) {
-    if (GTS_IS_FACE (i->data) && gts_face_has_parent_surface (i->data, s)) {
-      if (!t1)
-	t1 = i->data;
-      else if (!t2)
-	t2 = i->data;
-      else
-	g_return_if_fail (gts_edge_face_number (e, s) == 2);
-    }
-    i = i->next;
-  }
-  g_assert (t1 && t2);
-
-  gts_triangle_vertices_edges (t1, e, &v1, &v2, &v3, &e, &e1, &e2);
-  gts_triangle_vertices_edges (t2, e, &v4, &v5, &v6, &e, &e3, &e4);
-  g_assert (v2 == v4 && v1 == v5);
-
-  v3v6 = gts_vertices_are_connected (v3, v6);
-  if (!GTS_IS_EDGE (v3v6))
-    v3v6 = GTS_SEGMENT (gts_edge_new (s->edge_class, v3, v6));
-  f = gts_face_new (s->face_class, e1, GTS_EDGE (v3v6), e4);
-  if ((t = gts_triangle_is_duplicate (GTS_TRIANGLE (f))) &&
-      GTS_IS_FACE (t)) {
-    gts_object_destroy (GTS_OBJECT (f));
-    f = GTS_FACE (t);
-  }
-  gts_surface_add_face (s, f);
-
-  f = gts_face_new (s->face_class, GTS_EDGE (v3v6), e2, e3);
-  if ((t = gts_triangle_is_duplicate (GTS_TRIANGLE (f))) &&
-      GTS_IS_FACE (t)) {
-    gts_object_destroy (GTS_OBJECT (f));
-    f = GTS_FACE (t);
-  }
-  gts_surface_add_face (s, f);
-
-  gts_surface_remove_face (s, GTS_FACE (t1));
-  gts_surface_remove_face (s, GTS_FACE (t2));
-}
-
-/**
- * gts_edge_manifold_faces:
- * @e: a #GtsEdge.
- * @s: a #GtsSurface.
- * @f1: pointer for first face.
- * @f2: pointer for second face.
- *
- * If @e is a manifold edge of surface @s, fills @f1 and @f2 with the
- * faces belonging to @s and sharing @e.
- *
- * Returns: %TRUE if @e is a manifold edge, %FALSE otherwise.
- */
-gboolean gts_edge_manifold_faces (GtsEdge * e, GtsSurface * s,
-				  GtsFace ** f1, GtsFace ** f2)
-{
-  GSList * i;
-
-  g_return_val_if_fail (e != NULL, FALSE);
-  g_return_val_if_fail (s != NULL, FALSE);
-  g_return_val_if_fail (f1 != NULL, FALSE);
-  g_return_val_if_fail (f2 != NULL, FALSE);
-
-  *f1 = *f2 = NULL;
-  i = e->triangles;
-  while (i) {
-    if (GTS_IS_FACE (i->data) && gts_face_has_parent_surface (i->data, s)) {
-      if (!(*f1)) *f1 = i->data;
-      else if (!(*f2)) *f2 = i->data;
-      else return FALSE;
-    }
-    i = i->next;
-  }
-
-  return (*f1 && *f2);
-}
diff --git a/src/gts/eheap.c b/src/gts/eheap.c
deleted file mode 100644
index 29f462d..0000000
--- a/src/gts/eheap.c
+++ /dev/null
@@ -1,461 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <stdlib.h>
-#include "gts.h"
-
-#define PARENT(i) ((i) >= 2 ? (i)/2 : 0)
-#define LEFT_CHILD(i) (2*(i))
-#define RIGHT_CHILD(i) (2*(i) + 1)
-
-
-/**
- * gts_eheap_new:
- * @key_func: a #GtsKeyFunc or %NULL.
- * @data: user data to be passed to @key_func.
- *
- * Returns: a new #GtsEHeap using @key_func as key.
- */
-GtsEHeap * gts_eheap_new (GtsKeyFunc key_func,
-			  gpointer data)
-{
-  GtsEHeap * heap;
-
-  heap = g_malloc (sizeof(GtsEHeap));
-  heap->elts = g_ptr_array_new ();
-  heap->func = key_func;
-  heap->data = data;
-  heap->frozen = FALSE;
-  heap->randomized = FALSE;
-  return heap;
-}
-
-static void sift_up (GtsEHeap * heap, guint i)
-{
-  GtsEHeapPair * parent, * child;
-  guint p;
-  gpointer * pdata = heap->elts->pdata;
-  gdouble key;
-
-  child = pdata[i - 1];
-  key = child->key;
-  while ((p = PARENT (i))) {
-    parent = pdata[p - 1];
-    if (parent->key > key ||
-	(heap->randomized && parent->key == key && rand () < RAND_MAX/2)) {
-      pdata[p - 1] = child;
-      pdata[i - 1] = parent;
-      child->pos = p;
-      parent->pos = i;
-      i = p;
-    }
-    else
-      i = 0;
-  }
-}
-
-/**
- * gts_eheap_insert:
- * @heap: a #GtsEHeap.
- * @p: a pointer to add to the heap.
- *
- * Inserts a new element @p in the heap.
- *
- * Returns: a #GtsEHeapPair describing the position of the element in the heap.
- * This pointer is necessary for gts_eheap_remove() and 
- * gts_eheap_decrease_key().
- */
-GtsEHeapPair * gts_eheap_insert (GtsEHeap * heap, gpointer p)
-{
-  GtsEHeapPair * pair;
-  GPtrArray * elts;
-
-  g_return_val_if_fail (heap != NULL, NULL);
-  g_return_val_if_fail (heap->func != NULL, NULL);
-
-  elts = heap->elts;
-  pair = g_malloc (sizeof (GtsEHeapPair));
-  g_ptr_array_add (elts, pair);
-  pair->data = p;
-  pair->pos = elts->len;
-  pair->key = (*heap->func) (p, heap->data);
-  if (!heap->frozen)
-    sift_up (heap, elts->len);
-  return pair;
-}
-
-/**
- * gts_eheap_insert_with_key:
- * @heap: a #GtsEHeap.
- * @p: a pointer to add to the heap.
- * @key: the value of the key associated to @p.
- *
- * Inserts a new element @p in the heap.
- *
- * Returns: a #GtsEHeapPair describing the position of the element in the heap.
- * This pointer is necessary for gts_eheap_remove() and 
- * gts_eheap_decrease_key().
- */
-GtsEHeapPair * gts_eheap_insert_with_key (GtsEHeap * heap, 
-					  gpointer p, 
-					  gdouble key)
-{
-  GtsEHeapPair * pair;
-  GPtrArray * elts;
-
-  g_return_val_if_fail (heap != NULL, NULL);
-
-  elts = heap->elts;
-  pair = g_malloc (sizeof (GtsEHeapPair));
-  g_ptr_array_add (elts, pair);
-  pair->data = p;
-  pair->pos = elts->len;
-  pair->key = key;
-  if (!heap->frozen)
-    sift_up (heap, elts->len);
-  return pair;
-}
-
-static void sift_down (GtsEHeap * heap, guint i)
-{
-  GtsEHeapPair * left_child, * right_child, * child, * parent;
-  guint lc, rc, c;
-  gpointer * pdata = heap->elts->pdata;
-  guint len = heap->elts->len;
-  gdouble key;
-
-  lc = LEFT_CHILD (i);
-  rc = RIGHT_CHILD (i);
-  left_child = lc <= len ? pdata[lc - 1] : NULL;
-  right_child = rc <= len ? pdata[rc - 1] : NULL;
-
-  parent = pdata[i - 1];
-  key = parent->key;
-  while (left_child != NULL) {
-    if (right_child == NULL || left_child->key  < right_child->key) {
-      child = left_child;
-      c = lc;
-    }
-    else {
-      child = right_child;
-      c = rc;
-    }
-    if (key > child->key) {
-      pdata[i - 1] = child;
-      child->pos = i;
-      pdata[c - 1] = parent;
-      parent->pos = c;
-      i = c;
-      lc = LEFT_CHILD (i);
-      rc = RIGHT_CHILD (i);
-      left_child = lc <= len ? pdata[lc - 1] : NULL;
-      right_child = rc <= len ? pdata[rc - 1] : NULL;      
-    }
-    else
-      left_child = NULL;
-  }
-}
-
-/**
- * gts_eheap_remove_top:
- * @heap: a #GtsEHeap.
- * @key: a pointer on a gdouble or %NULL.
- *
- * Removes the element at the top of the heap and optionally (if @key is not
- * %NULL) returns the value of its key.
- *
- * Returns: the element at the top of the heap.
- */
-gpointer gts_eheap_remove_top (GtsEHeap * heap, gdouble * key)
-{
-  gpointer root;
-  GPtrArray * elts;
-  guint len;
-  GtsEHeapPair * pair;
-
-  g_return_val_if_fail (heap != NULL, NULL);
-
-  elts = heap->elts; 
-  len = elts->len;
-
-  if (len == 0)
-    return NULL;
-  if (len == 1) {
-    pair = g_ptr_array_remove_index (elts, 0);
-    root = pair->data;
-    if (key) 
-      *key = pair->key;
-    g_free (pair);
-    return root;
-  }
-
-  pair = elts->pdata[0];
-  root = pair->data;
-  if (key) 
-    *key = pair->key;
-  g_free (pair);
-  pair = g_ptr_array_remove_index (elts, len - 1);
-  elts->pdata[0] = pair;
-  pair->pos = 1;
-  sift_down (heap, 1);
-  return root;
-}
-
-/**
- * gts_eheap_top:
- * @heap: a #GtsEHeap.
- * @key: a pointer on a gdouble or %NULL.
- *
- * Returns: the element at the top of the heap and optionally (if @key is not
- * %NULL) its key.
- */
-gpointer gts_eheap_top (GtsEHeap * heap, gdouble * key)
-{
-  GtsEHeapPair * pair;
-  GPtrArray * elts;
-
-  g_return_val_if_fail (heap != NULL, NULL);
-
-  elts = heap->elts;
-
-  if (elts->len == 0)
-    return NULL;
-
-  pair = elts->pdata[0];
-  if (key)
-    *key = pair->key;
-  return pair->data;
-}
-
-/**
- * gts_eheap_destroy:
- * @heap: a #GtsEHeap.
- * 
- * Free all the memory allocated for @heap.
- */
-void gts_eheap_destroy (GtsEHeap * heap)
-{
-  guint i;
-
-  g_return_if_fail (heap != NULL);
-
-  for (i = 0; i < heap->elts->len; i++)
-    g_free (heap->elts->pdata[i]);
-  g_ptr_array_free (heap->elts, TRUE);
-  g_free (heap);
-}
-
-/**
- * gts_eheap_thaw:
- * @heap: a #GtsEHeap.
- *
- * If @heap has been frozen previously using gts_eheap_freeze(), reorder it
- * in O(n) time and unfreeze it.
- */
-void gts_eheap_thaw (GtsEHeap * heap)
-{
-  guint i;
-  
-  g_return_if_fail (heap != NULL);
-
-  if (!heap->frozen)
-    return;
-
-  for (i = heap->elts->len/2; i > 0; i--)
-    sift_down (heap, i);
-
-  heap->frozen = FALSE;
-}
-
-/**
- * gts_eheap_foreach:
- * @heap: a #GtsEHeap.
- * @func: the function to call for each element in the heap.
- * @data: to pass to @func.
- */
-void gts_eheap_foreach (GtsEHeap * heap, 
-			GFunc func,
-			gpointer data)
-{
-  guint i;
-  GPtrArray * elts;
-  
-  g_return_if_fail (heap != NULL);
-  g_return_if_fail (func != NULL);
-
-  elts = heap->elts;
-  for (i = 0; i < elts->len; i++)
-    (*func) (((GtsEHeapPair *) elts->pdata[i])->data, data);
-}
-
-/**
- * gts_eheap_remove:
- * @heap: a #GtsEHeap.
- * @p: a #GtsEHeapPair.
- *
- * Removes element corresponding to @p from @heap in O(log n).
- *
- * Returns: the element just removed from @heap.
- */
-gpointer gts_eheap_remove (GtsEHeap * heap, GtsEHeapPair * p)
-{
-  GtsEHeapPair ** pdata;
-  GtsEHeapPair * parent;
-  guint i, par;
-  gpointer data;
-
-  g_return_val_if_fail (heap != NULL, NULL);
-  g_return_val_if_fail (p != NULL, NULL);
-
-  pdata = (GtsEHeapPair **)heap->elts->pdata;
-  i = p->pos;
-  data = p->data;
-
-  g_return_val_if_fail (i > 0 && i <= heap->elts->len, NULL);
-  g_return_val_if_fail (p == pdata[i - 1], NULL);
-
-  /* move element to the top */
-  while ((par = PARENT (i))) {
-    parent = pdata[par - 1];
-    pdata[par - 1] = p;
-    pdata[i - 1] = parent;
-    p->pos = par;
-    parent->pos = i;
-    i = par;
-  }
-
-  gts_eheap_remove_top (heap, NULL);
-
-  return data;
-}
-
-/**
- * gts_eheap_decrease_key:
- * @heap: a #GtsEHeap.
- * @p: a #GtsEHeapPair.
- * @new_key: the new value of the key for this element. Must be smaller than
- * the current key.
- *
- * Decreases the value of the key of the element at position @p.
- */
-void gts_eheap_decrease_key (GtsEHeap * heap, 
-			     GtsEHeapPair * p,
-			     gdouble new_key)
-{
-  guint i;
-
-  g_return_if_fail (heap != NULL);
-  g_return_if_fail (p != NULL);
-
-  i = p->pos;
-  g_return_if_fail (i > 0 && i <= heap->elts->len);
-  g_return_if_fail (p == heap->elts->pdata[i - 1]);
-
-  g_return_if_fail (new_key <= p->key);
-
-  p->key = new_key;
-  if (!heap->frozen)
-    sift_up (heap, i);
-}
-
-/**
- * gts_eheap_freeze:
- * @heap: a #GtsEHeap.
- *
- * Freezes the heap. Any subsequent operation will not preserve the heap
- * property. Used in conjunction with gts_eheap_insert() and gts_eheap_thaw()
- * to create a heap in O(n) time.
- */
-void gts_eheap_freeze (GtsEHeap * heap)
-{
-  g_return_if_fail (heap != NULL);
-
-  heap->frozen = TRUE;
-}
-
-/**
- * gts_eheap_size:
- * @heap: a #GtsEHeap.
- *
- * Returns: the number of items in @heap.
- */
-guint gts_eheap_size (GtsEHeap * heap)
-{
-  g_return_val_if_fail (heap != NULL, 0);
-
-  return heap->elts->len;
-}
-
-/**
- * gts_eheap_update:
- * @heap: a #GtsEHeap.
- *
- * Updates the key of each element of @heap and reorders it.
- */
-void gts_eheap_update (GtsEHeap * heap)
-{
-  guint i, len;
-  GtsEHeapPair ** pairs;
-  gpointer data;
-  GtsKeyFunc func;
-
-  g_return_if_fail (heap != NULL);
-  g_return_if_fail (heap->func != NULL);
-
-  heap->frozen = TRUE;
-
-  len = heap->elts->len;
-  pairs = (GtsEHeapPair **) heap->elts->pdata;
-  data = heap->data;
-  func = heap->func;
-
-  for (i = 0; i < len; i++) {
-    GtsEHeapPair * pair = pairs[i];
-    pair->key = (*func) (pair->data, data);
-  }
-  
-  gts_eheap_thaw (heap);
-}
-
-/**
- * gts_eheap_key:
- * @heap: a #GtsEHeap.
- * @p: a pointer to be tested;
- *
- * Returns: the value of the key for pointer @p.
- */
-gdouble gts_eheap_key (GtsEHeap * heap, gpointer p)
-{
-  g_return_val_if_fail (heap != NULL, 0.);
-  g_return_val_if_fail (heap->func != NULL, 0.);
-
-  return (* heap->func) (p, heap->data);
-}
-
-/**
- * gts_eheap_randomized:
- * @heap: a #GtsEHeap.
- * @randomized: whether @heap should be randomized.
- */
-void gts_eheap_randomized (GtsEHeap * heap, gboolean randomized)
-{
-  g_return_if_fail (heap != NULL);
-
-  heap->randomized = randomized;
-}
diff --git a/src/gts/face.c b/src/gts/face.c
deleted file mode 100644
index f6009f1..0000000
--- a/src/gts/face.c
+++ /dev/null
@@ -1,297 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include "gts.h"
-
-gboolean gts_allow_floating_faces = FALSE;
-
-static void face_destroy (GtsObject * object)
-{
-  GtsFace * face = GTS_FACE (object);
-  GSList * i;
-
-  i = face->surfaces;
-  while (i) {
-    GSList * next = i->next;
-    gts_surface_remove_face (i->data, face);
-    i = next;
-  }
-  g_assert (face->surfaces == NULL);
-
-  (* GTS_OBJECT_CLASS (gts_face_class ())->parent_class->destroy) (object);
-}
-
-static void face_clone (GtsObject * clone, GtsObject * object)
-{
-  (* GTS_OBJECT_CLASS (gts_face_class ())->parent_class->clone) (clone, 
-								 object);
-  GTS_FACE (clone)->surfaces = NULL;
-}
-
-static void face_class_init (GtsFaceClass * klass)
-{
-  GTS_OBJECT_CLASS (klass)->clone = face_clone;
-  GTS_OBJECT_CLASS (klass)->destroy = face_destroy;
-}
-
-static void face_init (GtsFace * face)
-{
-  face->surfaces = NULL;
-}
-
-/**
- * gts_face_class:
- *
- * Returns: the #GtsFaceClass.
- */
-GtsFaceClass * gts_face_class (void)
-{
-  static GtsFaceClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo face_info = {
-      "GtsFace",
-      sizeof (GtsFace),
-      sizeof (GtsFaceClass),
-      (GtsObjectClassInitFunc) face_class_init,
-      (GtsObjectInitFunc) face_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_triangle_class ()), 
-				  &face_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_face_new:
- * @klass: a #GtsFaceClass.
- * @e1: a #GtsEdge.
- * @e2: a #GtsEdge.
- * @e3: a #GtsEdge.
- *
- * Returns: a new #GtsFace using @e1, @e2 and @e3 as edges.
- */
-GtsFace * gts_face_new (GtsFaceClass * klass,
-			GtsEdge * e1, GtsEdge * e2, GtsEdge * e3)
-{
-  GtsFace * f;
-
-  f = GTS_FACE (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  gts_triangle_set (GTS_TRIANGLE (f), e1, e2, e3);
-
-  return f;
-}
-
-/**
- * gts_face_has_parent_surface:
- * @f: a #GtsFace.
- * @s: a #GtsSurface.
- *
- * Returns: %TRUE if @f belongs to @s, %FALSE otherwise.
- */
-gboolean gts_face_has_parent_surface (GtsFace * f, GtsSurface * s)
-{
-  GSList * i;
-
-  g_return_val_if_fail (f != NULL, FALSE);
-
-  i = f->surfaces;
-  while (i) {
-    if (i->data == s)
-      return TRUE;
-    i = i->next;
-  }
-  return FALSE;
-}
-
-/**
- * gts_faces_from_edges:
- * @edges: a list of #GtsEdge.
- * @s: a #GtsSurface or %NULL.
- *
- * Builds a list of unique faces which belong to @s and have
- * one of their edges in @edges.
- * 
- * Returns: the list of faces.
- */
-GSList * gts_faces_from_edges (GSList * edges, GtsSurface * s)
-{
-  GHashTable * hash;
-  GSList * faces = NULL, * i;
-
-  hash = g_hash_table_new (NULL, NULL);
-  i = edges;
-  while (i) {
-    GSList * j = GTS_EDGE (i->data)->triangles;
-    while (j) {
-      GtsTriangle * t = j->data;
-      if (GTS_IS_FACE (t) &&
-	  (!s || gts_face_has_parent_surface (GTS_FACE (t), s)) && 
-	  g_hash_table_lookup (hash, t) == NULL) {
-	faces = g_slist_prepend (faces, t);
-	g_hash_table_insert (hash, t, i);
-      }
-      j = j->next;
-    }
-    i = i->next;
-  }
-  g_hash_table_destroy (hash);
-
-  return faces;
-}
-
-/**
- * gts_face_neighbor_number:
- * @f: a #GtsFace.
- * @s: a #GtsSurface or %NULL.
- *
- * Returns: the number of faces neighbors of @f and belonging to @s.
- */
-guint gts_face_neighbor_number (GtsFace * f, GtsSurface * s)
-{
-  GSList * i;
-  guint nn = 0;
-  GtsEdge * e[4], ** e1 = e;
-  
-  g_return_val_if_fail (f != NULL, 0);
-  
-  e[0] = GTS_TRIANGLE (f)->e1; 
-  e[1] = GTS_TRIANGLE (f)->e2; 
-  e[2] = GTS_TRIANGLE (f)->e3; 
-  e[3] = NULL;
-  while (*e1) {
-    i = (*e1++)->triangles;
-    while (i) {
-      GtsTriangle * t = i->data;
-      if (GTS_FACE (t) != f && 
-	  GTS_IS_FACE (t) && 
-	  (!s || gts_face_has_parent_surface (GTS_FACE (t), s)))
-	nn++;
-      i = i->next;
-    }
-  }
-
-  return nn;
-}
-
-/**
- * gts_face_neighbors:
- * @f: a #GtsFace.
- * @s: a #GtsSurface or %NULL.
- *
- * Returns: a list of unique #GtsFace neighbors of @f and belonging to @s.
- */
-GSList * gts_face_neighbors (GtsFace * f, GtsSurface * s)
-{
-  GSList * i, * list = NULL;
-  GtsEdge * e[4], ** e1 = e;
-  
-  g_return_val_if_fail (f != NULL, NULL);
-
-  e[0] = GTS_TRIANGLE (f)->e1; 
-  e[1] = GTS_TRIANGLE (f)->e2; 
-  e[2] = GTS_TRIANGLE (f)->e3; 
-  e[3] = NULL;
-  while (*e1) {
-    i = (*e1++)->triangles;
-    while (i) {
-      GtsTriangle * t = i->data;
-      if (GTS_FACE (t) != f && 
-	  GTS_IS_FACE (t) && 
-	  (!s || gts_face_has_parent_surface (GTS_FACE (t), s)))
-	list = g_slist_prepend (list, t);
-      i = i->next;
-    }
-  }
-
-  return list;
-}
-
-/**
- * gts_face_foreach_neighbor:
- * @f: a #GtsFace.
- * @s: a #GtsSurface or %NULL.
- * @func: a #GtsFunc.
- * @data: user data to pass to @func.
- *
- * Calls @func for each neighbor of @f belonging to @s (if not %NULL).
- */
-void gts_face_foreach_neighbor (GtsFace * f, 
-				GtsSurface * s, 
-				GtsFunc func,
-				gpointer data)
-{
-  GSList * i;
-  GtsEdge * e[4], ** e1 = e;
-  
-  g_return_if_fail (f != NULL);
-  g_return_if_fail (func != NULL);
-
-  e[0] = GTS_TRIANGLE (f)->e1;
-  e[1] = GTS_TRIANGLE (f)->e2; 
-  e[2] = GTS_TRIANGLE (f)->e3; 
-  e[3] = NULL;
-  while (*e1) {
-    i = (*e1++)->triangles;
-    while (i) {
-      GtsTriangle * t = i->data;
-      if (GTS_FACE (t) != f && 
-	  GTS_IS_FACE (t) && 
-	  (!s || gts_face_has_parent_surface (GTS_FACE (t), s)))
-	(* func) (t, data);
-      i = i->next;
-    }
-  }
-}
-
-static gboolean triangle_is_incompatible (GtsTriangle * t, GtsEdge * e, GtsSurface * s)
-{
-  GSList * i = e->triangles;
-
-  while (i) {
-    if (i->data != t &&
-	GTS_IS_FACE (i->data) &&
-	gts_face_has_parent_surface (i->data, s) &&
-	!gts_triangles_are_compatible (t, i->data, e))
-      return TRUE;
-    i = i->next;
-  }
-  return FALSE;
-}
-
-/**
- * gts_face_is_compatible:
- * @f: a #GtsFace.
- * @s: a #GtsSurface.
- *
- * Returns: %TRUE if @f is compatible with all its neighbors belonging
- * to @s, %FALSE otherwise.
- */
-gboolean gts_face_is_compatible (GtsFace * f, GtsSurface * s)
-{
-  g_return_val_if_fail (f != NULL, FALSE);
-  g_return_val_if_fail (s != NULL, FALSE);
-
-  return !(triangle_is_incompatible (GTS_TRIANGLE (f), GTS_TRIANGLE (f)->e1, s) ||
-	   triangle_is_incompatible (GTS_TRIANGLE (f), GTS_TRIANGLE (f)->e2, s) ||
-	   triangle_is_incompatible (GTS_TRIANGLE (f), GTS_TRIANGLE (f)->e3, s));
-}
diff --git a/src/gts/fifo.c b/src/gts/fifo.c
deleted file mode 100644
index 8b3d2b6..0000000
--- a/src/gts/fifo.c
+++ /dev/null
@@ -1,192 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include "gts.h"
-
-struct _GtsFifo {
-  GList * head;
-  GList * tail;
-};
-
-/**
- * gts_fifo_new:
- *
- * Returns: a new #GtsFifo.
- */
-GtsFifo * gts_fifo_new ()
-{
-  GtsFifo * fifo = g_malloc (sizeof (GtsFifo));
-
-  fifo->head = fifo->tail = NULL;
-  return fifo;
-}
-
-/**
- * gts_fifo_write:
- * @fifo: a #GtsFifo.
- * @fp: a file pointer.
- *
- * Writes the content of @fifo in @fp.
- */
-void gts_fifo_write (GtsFifo * fifo, FILE * fp)
-{
-  GList * i;
-
-  g_return_if_fail (fifo != NULL);
-  g_return_if_fail (fp != NULL);
-
-  fprintf (fp, "[");
-  i = fifo->head;
-  while (i) {
-    fprintf (fp, "%p ", i->data);
-    i = i->next;
-  }
-  fprintf (fp, "]");
-}
-
-/**
- * gts_fifo_push:
- * @fifo: a #GtsFifo.
- * @data: data to add to @fifo.
- *
- * Push @data into @fifo.
- */
-void gts_fifo_push (GtsFifo * fifo, gpointer data)
-{
-  g_return_if_fail (fifo != NULL);
-
-  fifo->head = g_list_prepend (fifo->head, data);
-  if (fifo->tail == NULL)
-    fifo->tail = fifo->head;
-}
-
-/**
- * gts_fifo_pop:
- * @fifo: a #GtsFifo.
- *
- * Removes the first element from @fifo.
- *
- * Returns: the first element in @fifo or %NULL if @fifo is empty.
- */
-gpointer gts_fifo_pop (GtsFifo * fifo)
-{
-  gpointer data;
-  GList * tail;
-
-  g_return_val_if_fail (fifo != NULL, NULL);
-
-  if (fifo->tail == NULL)
-    return NULL;
-  tail = fifo->tail->prev;
-  data = fifo->tail->data;
-  fifo->head = g_list_remove_link (fifo->head, fifo->tail);
-  g_list_free_1 (fifo->tail);
-  fifo->tail = tail;
-  return data;
-}
-
-/**
- * gts_fifo_top:
- * @fifo: a #GtsFifo.
- *
- * Returns: the first element in @fifo or %NULL if @fifo is empty.
- */
-gpointer gts_fifo_top (GtsFifo * fifo)
-{
-  g_return_val_if_fail (fifo != NULL, NULL);
-
-  if (fifo->tail == NULL)
-    return NULL;
-  return fifo->tail->data;
-}
-
-/**
- * gts_fifo_size:
- * @fifo: a #GtsFifo.
- *
- * Returns: the number of elements in @fifo.
- */
-guint gts_fifo_size (GtsFifo * fifo)
-{
-  g_return_val_if_fail (fifo != NULL, 0);
-
-  return g_list_length (fifo->head);
-}
-
-/**
- * gts_fifo_destroy:
- * @fifo: a #GtsFifo.
- *
- * Frees all the memory allocated for @fifo.
- */
-void gts_fifo_destroy (GtsFifo * fifo)
-{
-  g_return_if_fail (fifo != NULL);
-  g_list_free (fifo->head);
-  g_free (fifo);
-}
-
-/**
- * gts_fifo_is_empty:
- * @fifo: a #GtsFifo.
- * 
- * Returns: %TRUE if @fifo is empty, %FALSE otherwise.
- */
-gboolean gts_fifo_is_empty (GtsFifo * fifo)
-{
-  g_return_val_if_fail (fifo != NULL, TRUE);
-
-  return (fifo->head == NULL);
-}
-
-/**
- * gts_fifo_foreach:
- * @fifo: a #GtsFifo.
- * @func: a #GtsFunc.
- * @data: user data to be passed to @func.
- *
- * Calls @func in order for each item in @fifo, passing @data.
- */
-void gts_fifo_foreach (GtsFifo * fifo, GtsFunc func, gpointer data)
-{
-  GList * i;
-
-  g_return_if_fail (fifo != NULL);
-  g_return_if_fail (func != NULL);
-
-  i = fifo->tail;
-  while (i) {
-    (* func) (i->data, data);
-    i = i->prev;
-  }
-}
-
-/**
- * gts_fifo_reverse:
- * @fifo: a #GtsFifo.
- *
- * Reverses the order of elements in @fifo.
- */
-void gts_fifo_reverse (GtsFifo * fifo)
-{
-  g_return_if_fail (fifo != NULL);
-
-  fifo->tail = fifo->head;
-  fifo->head = g_list_reverse (fifo->head);
-}
diff --git a/src/gts/graph.c b/src/gts/graph.c
deleted file mode 100644
index 1566c95..0000000
--- a/src/gts/graph.c
+++ /dev/null
@@ -1,1776 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <math.h>
-#include <stdlib.h>
-#include "gts.h"
-
-/* GtsGNode */
-
-gboolean gts_allow_floating_gnodes = FALSE;
-
-static void gnode_remove_container (GtsContainee * i, GtsContainer * c)
-{
-  (* GTS_CONTAINEE_CLASS (GTS_OBJECT_CLASS (gts_gnode_class ())->parent_class)->remove_container) (i, c);
-  if (GTS_SLIST_CONTAINEE (i)->containers == NULL && 
-      !gts_allow_floating_gnodes &&
-      !GTS_OBJECT_DESTROYED(GTS_OBJECT (i)))
-    gts_object_destroy (GTS_OBJECT (i));
-}
-
-static void gnode_class_init (GtsGNodeClass * klass)
-{
-  klass->weight = NULL;
-
-  GTS_CONTAINEE_CLASS (klass)->remove_container = gnode_remove_container;
-}
-
-static void gnode_init (GtsGNode * n)
-{
-  n->level = 0;
-}
-
-/**
- * gts_gnode_class:
- * 
- * Returns: the #GtsGNodeClass.
- */
-GtsGNodeClass * gts_gnode_class (void)
-{
-  static GtsGNodeClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo gnode_info = {
-      "GtsGNode",
-      sizeof (GtsGNode),
-      sizeof (GtsGNodeClass),
-      (GtsObjectClassInitFunc) gnode_class_init,
-      (GtsObjectInitFunc) gnode_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = 
-      gts_object_class_new (GTS_OBJECT_CLASS (gts_slist_container_class ()),
-			    &gnode_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_gnode_new:
- * @klass: a #GtsGNodeClass.
- *
- * Returns: a new #GtsGNode.
- */
-GtsGNode * gts_gnode_new (GtsGNodeClass * klass)
-{
-  GtsGNode * object;
-
-  object = GTS_GNODE (gts_object_new (GTS_OBJECT_CLASS (klass)));
-
-  return object;
-}
-
-/**
- * gts_gnode_foreach_neighbor:
- * @n: a #GtsGNode.
- * @g: a #GtsGraph or %NULL.
- * @func: a #GtsFunc.
- * @data: user data to be passed to @func.
- *
- * Calls @func for each neighbor #GtsGNode of @n (belonging to @g if
- * @g is not %NULL.  
- */
-void gts_gnode_foreach_neighbor (GtsGNode * n, 
-				 GtsGraph * g,
-				 GtsFunc func,
-				 gpointer data)
-{
-  GSList * i;
-
-  g_return_if_fail (n != NULL);
-  g_return_if_fail (func != NULL);
-
-  i = GTS_SLIST_CONTAINER (n)->items;
-  while (i) {
-    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
-    if (g == NULL || gts_containee_is_contained (GTS_CONTAINEE (n1),
-						 GTS_CONTAINER (g)))
-      (* func) (n1, data);
-    i = i->next;
-  }
-}
-
-/**
- * gts_gnode_foreach_edge:
- * @n: a #GtsGNode.
- * @g: a #GtsGraph or %NULL.
- * @func: a #GtsFunc.
- * @data: user data to be passed to @func.
- *
- * Calls @func for each #GtsGEdge connecting @n to another #GtsGNode
- * (belonging to @g if @g is not %NULL.  
- */
-void gts_gnode_foreach_edge (GtsGNode * n, 
-			     GtsGraph * g,
-			     GtsFunc func,
-			     gpointer data)
-{
-  GSList * i;
-
-  g_return_if_fail (n != NULL);
-  g_return_if_fail (func != NULL);
-
-  i = GTS_SLIST_CONTAINER (n)->items;
-  while (i) {
-    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
-    if (g == NULL || gts_containee_is_contained (GTS_CONTAINEE (n1),
-						 GTS_CONTAINER (g)))
-      (* func) (i->data, data);
-    i = i->next;
-  }
-}
-
-/**
- * gts_gnode_degree:
- * @n: a #GtsGNode.
- * @g: a #GtsGraph or %NULL.
- *
- * Returns: the number of neighbors of @n (belonging to @g if @g is not %NULL).
- */
-guint gts_gnode_degree (GtsGNode * n,
-			GtsGraph * g)
-{
-  GSList * i;
-  guint nn = 0;
-
-  g_return_val_if_fail (n != NULL, 0);
-
-  i = GTS_SLIST_CONTAINER (n)->items;
-  while (i) {
-    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
-    if (g == NULL || gts_containee_is_contained (GTS_CONTAINEE (n1),
-						 GTS_CONTAINER (g)))
-      nn++;
-    i = i->next;
-  }
-
-  return nn;
-}
-
-/**
- * gts_gnode_move_cost:
- * @n: a #GtsGNode.
- * @src: a #GtsGraph containing @n.
- * @dst: another #GtsGraph.
- *
- * Returns: the cost (increase in the sum of the weights of the edges cut) of
- * moving @n from @src to @dst.
- */
-gfloat gts_gnode_move_cost (GtsGNode * n,
-			    GtsGraph * src,
-			    GtsGraph * dst)
-{
-  GSList * i;
-  gfloat cost = 0.;
-  
-  g_return_val_if_fail (n != NULL, G_MAXFLOAT);
-  g_return_val_if_fail (src != NULL, G_MAXFLOAT);
-  g_return_val_if_fail (dst != NULL, G_MAXFLOAT);
-  g_return_val_if_fail (gts_containee_is_contained (GTS_CONTAINEE (n),
-						    GTS_CONTAINER (src)),
-			G_MAXFLOAT);
-
-  i = GTS_SLIST_CONTAINER (n)->items;
-  while (i) {
-    GtsGEdge * ge = i->data;
-    GtsGNode * neighbor = GTS_GNODE_NEIGHBOR (n, ge);
-
-    if (gts_containee_is_contained (GTS_CONTAINEE (neighbor), 
-				    GTS_CONTAINER (src)))
-      cost += gts_gedge_weight (ge);
-    else if (gts_containee_is_contained (GTS_CONTAINEE (neighbor), 
-					 GTS_CONTAINER (dst)))
-      cost -= gts_gedge_weight (ge);
-    i = i->next;
-  }
-  
-  return cost;
-}
-
-/**
- * gts_gnode_weight:
- * @n: a #GtsGNode.
- *
- * Returns: the weight of @n as defined by the weight() method of the
- * #GtsGNodeClass.  
- */
-gfloat gts_gnode_weight (GtsGNode * n)
-{
-  g_return_val_if_fail (n != NULL, 0.);
-
-  if (GTS_GNODE_CLASS (GTS_OBJECT (n)->klass)->weight)
-    return (* GTS_GNODE_CLASS (GTS_OBJECT (n)->klass)->weight) (n);
-  return 1.;
-}
-
-/* GtsNGNode */
-
-static void ngnode_init (GtsNGNode * n)
-{
-  n->id = 0;
-}
-
-/**
- * gts_ngnode_class:
- *
- * Returns: the #GtsNGNodeClass.
- */
-GtsNGNodeClass * gts_ngnode_class (void)
-{
-  static GtsNGNodeClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo ngnode_info = {
-      "GtsNGNode",
-      sizeof (GtsNGNode),
-      sizeof (GtsNGNodeClass),
-      (GtsObjectClassInitFunc) NULL,
-      (GtsObjectInitFunc) ngnode_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_gnode_class ()),
-				  &ngnode_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_ngnode_new:
- * @klass: a #GtsNGNodeClass.
- *
- * Returns: a new #GtsNGNode with identity @id.
- */
-GtsNGNode * gts_ngnode_new (GtsNGNodeClass * klass,
-			    guint id)
-{
-  GtsNGNode * n;
-
-  n = GTS_NGNODE (gts_gnode_new (GTS_GNODE_CLASS (klass)));
-  n->id = id;
-
-  return n;
-}
-
-/* GtsWGNode */
-
-static gfloat wgnode_weight (GtsGNode * n)
-{
-  return GTS_WGNODE (n)->weight;
-}
-
-static void wgnode_class_init (GtsWGNodeClass * klass)
-{
-  GTS_GNODE_CLASS (klass)->weight = wgnode_weight;
-}
-
-static void wgnode_init (GtsWGNode * n)
-{
-  n->weight = 1.;
-}
-
-/**
- * gts_wgnode_class:
- *
- * Returns: the #GtsWGNodeClass.
- */
-GtsWGNodeClass * gts_wgnode_class (void)
-{
-  static GtsWGNodeClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo wgnode_info = {
-      "GtsWGNode",
-      sizeof (GtsWGNode),
-      sizeof (GtsWGNodeClass),
-      (GtsObjectClassInitFunc) wgnode_class_init,
-      (GtsObjectInitFunc) wgnode_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_gnode_class ()),
-				  &wgnode_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_wgnode_new:
- * @klass: a #GtsWGNodeClass.
- * @weight: the weight of the #GtsWGNode to create.
- *
- * Returns: a new #GtsWGNode of weight @weight.
- */
-GtsWGNode * gts_wgnode_new (GtsWGNodeClass * klass,
-			    gfloat weight)
-{
-  GtsWGNode * n;
-
-  n = GTS_WGNODE (gts_gnode_new (GTS_GNODE_CLASS (klass)));
-  n->weight = weight;
-
-  return n;
-}
-
-/* GtsPNode */
-
-static void pnode_write (GtsGNode * n, FILE * fp)
-{
-  if (GTS_IS_NVERTEX (GTS_PNODE (n)->data))
-    fprintf (fp, "label=\"%p:%s\",", 
-	     GTS_PNODE (n)->data,
-	     GTS_NVERTEX (GTS_PNODE (n)->data)->name);
-  else
-    fprintf (fp, "label=\"%p\",", GTS_PNODE (n)->data);
-}
-
-static void pnode_class_init (GtsPNodeClass * klass)
-{
-  GTS_GNODE_CLASS (klass)->write = pnode_write;
-}
-
-static void pnode_init (GtsPNode * pn)
-{
-  pn->data = NULL;
-}
-
-/**
- * gts_pnode_class:
- *
- * Returns: the #GtsPNodeClass.
- */
-GtsPNodeClass * gts_pnode_class (void)
-{
-  static GtsPNodeClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo pnode_info = {
-      "GtsPNode",
-      sizeof (GtsPNode),
-      sizeof (GtsPNodeClass),
-      (GtsObjectClassInitFunc) pnode_class_init,
-      (GtsObjectInitFunc) pnode_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_gnode_class ()),
-				  &pnode_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_pnode_new:
- * @klass: a #GtsPNodeClass.
- * @data: user data.
- *
- * Returns: a new #GtsPNode associated with @data.
- */
-GtsPNode * gts_pnode_new (GtsPNodeClass * klass, gpointer data)
-{
-  GtsPNode * pn;
-
-  pn = GTS_PNODE (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  pn->data = data;
-
-  return pn;
-}
-
-/* GtsFNode */
-
-static void fnode_write (GtsGNode * n, FILE * fp)
-{
-  fprintf (fp, "label=\"%p\",", GTS_FNODE (n)->f);
-}
-
-static void fnode_class_init (GtsGNodeClass * klass)
-{
-  klass->write = fnode_write;
-}
-
-static void fnode_init (GtsFNode * fn)
-{
-  fn->f = NULL;
-}
-
-/**
- * gts_fnode_class:
- *
- * Returns: the #GtsFNodeClass.
- */
-GtsFNodeClass * gts_fnode_class (void)
-{
-  static GtsFNodeClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo fnode_info = {
-      "GtsFNode",
-      sizeof (GtsFNode),
-      sizeof (GtsFNodeClass),
-      (GtsObjectClassInitFunc) fnode_class_init,
-      (GtsObjectInitFunc) fnode_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_gnode_class ()),
-				  &fnode_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_fnode_new:
- * @klass: a #GtsFNodeClass.
- * @f: a #GtsFace.
- *
- * Returns: a new #GtsFNode associated with face @f.
- */
-GtsFNode * gts_fnode_new (GtsFNodeClass * klass, GtsFace * f)
-{
-  GtsFNode * fn;
-
-  g_return_val_if_fail (f != NULL, NULL);
-
-  fn = GTS_FNODE (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  fn->f = f;
-
-  return fn;
-}
-
-/* GtsGEdge */
-
-static void gedge_destroy (GtsObject * object)
-{
-  GtsGEdge * ge = GTS_GEDGE (object);
-
-  if (ge->n1)
-    gts_container_remove (GTS_CONTAINER (ge->n1), GTS_CONTAINEE (ge));
-  if (ge->n2)
-    gts_container_remove (GTS_CONTAINER (ge->n2), GTS_CONTAINEE (ge));
-
-  (* GTS_OBJECT_CLASS (gts_gedge_class ())->parent_class->destroy) (object);
-}
-
-static void gedge_remove_container (GtsContainee * i, GtsContainer * c)
-{
-  GtsGEdge * ge = GTS_GEDGE (i);
-  GtsGNode * n1 = ge->n1;
-  GtsGNode * n2 = ge->n2;
-
-  ge->n1 = ge->n2 = NULL;
-  if (n1 != NULL && n2 != NULL) {
-    if (GTS_CONTAINER (n1) == c) {
-      if (n2 && n2 != n1) gts_container_remove (GTS_CONTAINER (n2), i);
-    }
-    else if (GTS_CONTAINER (n2) == c) {
-      if (n1 && n1 != n2) gts_container_remove (GTS_CONTAINER (n1), i);
-    }
-    else
-      g_assert_not_reached ();
-    (* GTS_OBJECT_CLASS (gts_gedge_class ())->parent_class->destroy)
-      (GTS_OBJECT (i));
-  }
-}
-
-static gboolean gedge_is_contained (GtsContainee * i, GtsContainer * c)
-{
-  GtsGEdge * ge = GTS_GEDGE (i);
-
-  if (GTS_CONTAINER (ge->n1) == c || GTS_CONTAINER (ge->n2) == c)
-    return TRUE;
-  return FALSE;
-}
-
-static void gedge_class_init (GtsGEdgeClass * klass)
-{
-  klass->link = NULL;
-  klass->weight = NULL;
-
-  GTS_CONTAINEE_CLASS (klass)->remove_container = gedge_remove_container;
-  GTS_CONTAINEE_CLASS (klass)->is_contained = gedge_is_contained;
-
-  GTS_OBJECT_CLASS (klass)->destroy = gedge_destroy;
-}
-
-static void gedge_init (GtsGEdge * object)
-{
-  object->n1 = object->n2 = NULL;
-}
-
-/**
- * gts_gedge_class:
- *
- * Returns: the #GtsGEdgeClass.
- */
-GtsGEdgeClass * gts_gedge_class (void)
-{
-  static GtsGEdgeClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo gedge_info = {
-      "GtsGEdge",
-      sizeof (GtsGEdge),
-      sizeof (GtsGEdgeClass),
-      (GtsObjectClassInitFunc) gedge_class_init,
-      (GtsObjectInitFunc) gedge_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_containee_class ()),
-				  &gedge_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_gedge_new:
- * @klass: a #GtsGEdgeClass.
- * @n1: a #GtsGNode.
- * @n2: another #GtsGNode.
- *
- * Returns: a new #GtsGEdge linking @n1 and @n2.
- */
-GtsGEdge * gts_gedge_new (GtsGEdgeClass * klass, GtsGNode * n1, GtsGNode * n2)
-{
-  GtsGEdge * object;
-
-  g_return_val_if_fail (n1 != NULL, NULL);
-  g_return_val_if_fail (n2 != NULL, NULL);
-
-  object = GTS_GEDGE (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  object->n1 = n1;
-  gts_container_add (GTS_CONTAINER (n1), GTS_CONTAINEE (object));
-  object->n2 = n2;
-  if (n1 != n2)
-    gts_container_add (GTS_CONTAINER (n2), GTS_CONTAINEE (object));
-
-  if (klass->link)
-    object = (* klass->link) (object, n1, n2);
-
-  return object;
-}
-
-/**
- * gts_gedge_weight:
- * @e: a #GtsGEdge.
- *
- * Returns: the weight of edge @e as defined by the weight() method of
- * #GtsGEdgeClass.  
- */
-gfloat gts_gedge_weight (GtsGEdge * e)
-{
-  g_return_val_if_fail (e != NULL, 0.);
-
-  if (GTS_GEDGE_CLASS (GTS_OBJECT (e)->klass)->weight)
-    return (* GTS_GEDGE_CLASS (GTS_OBJECT (e)->klass)->weight) (e);
-  return 1.;
-}
-
-/* GtsPGEdge */
-
-static void pgedge_write (GtsGEdge * ge, FILE * fp)
-{
-  if (GTS_IS_EDGE (GTS_PGEDGE (ge)->data)) {
-    GtsEdge * e = GTS_PGEDGE (ge)->data;
-    guint n = g_slist_length (e->triangles);
-
-    fprintf (fp, "label=\"%p:%s:%d\",color=%s", e,
-	     GTS_IS_NEDGE (e) ? GTS_NEDGE (e)->name : "",
-	     n,
-	     n == 0 ? "black" : 
-             n == 1 ? "blue" :
-	     n == 2 ? "green" :
-	     n == 3 ? "violet" :
-	     n == 4 ? "red" : 
-	     "pink");
-  }
-  else
-    fprintf (fp, "label=\"%p\",", GTS_PGEDGE (ge)->data);
-}
-
-static void pgedge_class_init (GtsPGEdgeClass * klass)
-{
-  GTS_GEDGE_CLASS (klass)->write = pgedge_write;
-}
-
-static void pgedge_init (GtsPGEdge * e)
-{
-  e->data = NULL;
-}
-
-/**
- * gts_pgedge_class:
- * 
- * Returns: the #GtsPGEdgeClass.
- */
-GtsPGEdgeClass * gts_pgedge_class (void)
-{
-  static GtsPGEdgeClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo pgedge_info = {
-      "GtsPGEdge",
-      sizeof (GtsPGEdge),
-      sizeof (GtsPGEdgeClass),
-      (GtsObjectClassInitFunc) pgedge_class_init,
-      (GtsObjectInitFunc) pgedge_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_gedge_class ()),
-				  &pgedge_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_pgedge_new:
- * @klass: a #GtsPGEdgeClass.
- * @n1: a #GtsGNode.
- * @n2: another #GtsGNode.
- * @data: user data.
- *
- * Returns: a new #GtsPGEdge associated with @data linking @n1 and @n2.
- */ 
-GtsPGEdge * gts_pgedge_new (GtsPGEdgeClass * klass,
-			    GtsGNode * g1,
-			    GtsGNode * g2,
-			    gpointer data)
-{
-  GtsPGEdge * we;
-
-  we = GTS_PGEDGE (gts_gedge_new (GTS_GEDGE_CLASS (klass), g1, g2));
-  we->data = data;
-
-  return we;
-}
-
-/* GtsWGEdge */
-
-static gfloat wgedge_weight (GtsGEdge * e)
-{
-  return GTS_WGEDGE (e)->weight;
-}
-
-static void wgedge_class_init (GtsWGEdgeClass * klass)
-{
-  GTS_GEDGE_CLASS (klass)->weight = wgedge_weight;
-}
-
-static void wgedge_init (GtsWGEdge * e)
-{
-  e->weight = 1.;
-}
-
-/**
- * gts_wgedge_class:
- * 
- * Returns: the #GtsWGEdgeClass.
- */
-GtsWGEdgeClass * gts_wgedge_class (void)
-{
-  static GtsWGEdgeClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo wgedge_info = {
-      "GtsWGEdge",
-      sizeof (GtsWGEdge),
-      sizeof (GtsWGEdgeClass),
-      (GtsObjectClassInitFunc) wgedge_class_init,
-      (GtsObjectInitFunc) wgedge_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_gedge_class ()),
-				  &wgedge_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_wgedge_new:
- * @klass: a #GtsWGEdgeClass.
- * @n1: a #GtsGNode.
- * @n2: another #GtsGNode.
- * @weight: the weight of the new edge.
- *
- * Returns: a new #GtsWGEdge of weight @weight linking @n1 and @n2.
- */ 
-GtsWGEdge * gts_wgedge_new (GtsWGEdgeClass * klass,
-			    GtsGNode * g1,
-			    GtsGNode * g2,
-			    gfloat weight)
-{
-  GtsWGEdge * we;
-
-  we = GTS_WGEDGE (gts_gedge_new (GTS_GEDGE_CLASS (klass), g1, g2));
-  we->weight = weight;
-
-  return we;
-}
-
-/* GtsGraph */
-
-static void graph_init (GtsGraph * g)
-{
-  g->graph_class = gts_graph_class ();
-  g->node_class  = gts_gnode_class ();
-  g->edge_class  = gts_gedge_class ();
-}
-
-static void graph_write (GtsObject * object, FILE * fp)
-{
-  GtsGraph * graph = GTS_GRAPH (object);
-
-  fprintf (fp, " %s %s %s",
-	   object->klass->info.name,
-	   GTS_OBJECT_CLASS (graph->node_class)->info.name,
-	   GTS_OBJECT_CLASS (graph->edge_class)->info.name);
-}
-
-static void graph_read (GtsObject ** object, GtsFile * f)
-{
-  GtsObjectClass * klass;
-
-  if (f->type != GTS_STRING) {
-    gts_file_error (f, "expecting a string (GtsGNodeClass)");
-    return;
-  }
-  klass = gts_object_class_from_name (f->token->str);
-  if (klass == NULL) {
-    gts_file_error (f, "unknown class `%s'", f->token->str);
-    return;
-  }
-  if (!gts_object_class_is_from_class (klass, gts_gnode_class ())) {
-    gts_file_error (f, "class `%s' is not a GtsGNodeClass", f->token->str);
-    return;
-  }
-  GTS_GRAPH (*object)->node_class = GTS_GNODE_CLASS (klass);
-  gts_file_next_token (f);
-
-  if (f->type != GTS_STRING) {
-    gts_file_error (f, "expecting a string (GtsGEdgeClass)");
-    return;
-  }
-  klass = gts_object_class_from_name (f->token->str);
-  if (klass == NULL) {
-    gts_file_error (f, "unknown class `%s'", f->token->str);
-    return;
-  }
-  if (!gts_object_class_is_from_class (klass, gts_gedge_class ())) {
-    gts_file_error (f, "class `%s' is not a GtsGEdgeClass", f->token->str);
-    return;
-  }
-  GTS_GRAPH (*object)->edge_class = GTS_GEDGE_CLASS (klass);
-  gts_file_next_token (f);
-}
-
-static void graph_class_init (GtsGraphClass * klass)
-{
-  klass->weight = NULL;
-
-  GTS_OBJECT_CLASS (klass)->write = graph_write;
-  GTS_OBJECT_CLASS (klass)->read = graph_read;
-}
-
-/**
- * gts_graph_class:
- *
- * Returns: the #GtsGraphClass.
- */
-GtsGraphClass * gts_graph_class (void)
-{
-  static GtsGraphClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo graph_info = {
-      "GtsGraph",
-      sizeof (GtsGraph),
-      sizeof (GtsGraphClass),
-      (GtsObjectClassInitFunc) graph_class_init,
-      (GtsObjectInitFunc) graph_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_hash_container_class ()),
-				  &graph_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_graph_new:
- * @klass: a #GtsGraphClass.
- * @node_class: a #GtsGNodeClass.
- * @edge_class: a #GtsGEdgeClass.
- *
- * Returns: a new #GtsGraph using @node_class and @edge_class as node types.
- */
-GtsGraph * gts_graph_new (GtsGraphClass * klass,
-			  GtsGNodeClass * node_class,
-			  GtsGEdgeClass * edge_class)
-{
-  GtsGraph * g;
-
-  g_return_val_if_fail (klass != NULL, NULL);
-  g_return_val_if_fail (node_class != NULL, NULL);
-  g_return_val_if_fail (edge_class != NULL, NULL);
-
-  g = GTS_GRAPH (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  g->node_class = node_class;
-  g->edge_class = edge_class;
-
-  return g;
-}
-
-static void compute_degree (GtsGNode * n, gpointer * data)
-{
-  GtsGraph * g = data[0];
-  GtsRange * degree = data[1];
-
-  gts_range_add_value (degree, gts_gnode_degree (n, g));
-}
-
-/**
- * gts_graph_print_stats:
- * @g: a #GtsGraph.
- * @fp: a file pointer.
- *
- * Writes to @fp a summary of the properties of @g.
- */
-void gts_graph_print_stats (GtsGraph * g, FILE * fp)
-{
-  GtsRange degree;
-  gpointer data[2];
-
-  g_return_if_fail (g != NULL);
-  g_return_if_fail (fp != NULL);
-
-  fprintf (fp, "# nodes: %d weight: %g\n", 
-	   gts_container_size (GTS_CONTAINER (g)),
-	   gts_graph_weight (g));
-  fprintf (fp, "#   degree: ");
-  gts_range_init (&degree);
-  data[0] = g;
-  data[1] = &degree;
-  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) compute_degree, data);
-  gts_range_update (&degree);
-  gts_range_print (&degree, fp);
-  fprintf (fp, "\n");
-  fprintf (fp, "#   edges cut: %d edges cut weight: %g\n", 
-	   gts_graph_edges_cut (g),
-	   gts_graph_edges_cut_weight (g));
-}
-
-struct _GtsGraphTraverse {
-  GtsFifo * q;
-  GtsGraph * g;
-};
-
-static void reset_level (GtsGNode * n)
-{
-  n->level = 0;
-}
-
-/**
- * gts_graph_traverse_new:
- * @g: a #GtsGraph.
- * @n: a #GtsGNode belonging to @g.
- * @type: the type of traversal.
- * @reinit: if %TRUE, the traversal is reinitialized.
- *
- * Returns: a new #GtsGraphTraverse initialized for the traversal of
- * @g of type @type, starting from @n.  
- */
-GtsGraphTraverse * gts_graph_traverse_new (GtsGraph * g, 
-					   GtsGNode * n,
-					   GtsTraverseType type,
-					   gboolean reinit)
-{
-  GtsGraphTraverse * t;
-
-  g_return_val_if_fail (g != NULL, NULL);
-  g_return_val_if_fail (n != NULL, NULL);
-  g_return_val_if_fail (gts_containee_is_contained (GTS_CONTAINEE (n), 
-						    GTS_CONTAINER (g)), 
-			NULL);
-
-  if (reinit)
-    gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) reset_level, NULL);
-
-  t = g_malloc (sizeof (GtsGraphTraverse));
-  t->q = gts_fifo_new ();
-  t->g = g;
-  n->level = 1;
-  gts_fifo_push (t->q, n);
-
-  return t;
-}
-
-static void push_neighbor (GtsGNode * n, gpointer * data)
-{
-  GtsFifo * q = data[0];
-  GtsGNode * u = data[1];
-
-  if (n->level == 0) {
-    n->level = u->level + 1;
-    gts_fifo_push (q, n);
-  }
-}
-
-/**
- * gts_graph_traverse_next:
- * @t: a #GtsGraphTraverse.
- *
- * Returns: the next #GtsGNode of the traversal defined by @t or %NULL
- * if the traversal is complete.
- */
-GtsGNode * gts_graph_traverse_next (GtsGraphTraverse * t) 
-{ 
-  GtsGNode * u;
-
-  g_return_val_if_fail (t != NULL, NULL);
-
-  u = gts_fifo_pop (t->q);
-  if (u) {
-    gpointer data[2];
-
-    data[0] = t->q;
-    data[1] = u;
-    gts_gnode_foreach_neighbor (u, t->g, (GtsFunc) push_neighbor, data);
-  }
-  
-  return u;
-}
-
-/**
- * gts_graph_traverse_what_next:
- * @t: a #GtsGraphTraverse.
- *
- * Returns: the next #GtsGNode of the traversal defined by @t or %NULL
- * if the traversal is complete but without advancing the traversal.
- */
-GtsGNode * gts_graph_traverse_what_next (GtsGraphTraverse * t)
-{
-  g_return_val_if_fail (t != NULL, NULL);
-
-  return gts_fifo_top (t->q);
-}
-
-/**
- * gts_graph_traverse_destroy:
- * @t: a #GtsGraphTraverse.
- *
- * Frees all the memory allocated for @t.
- */
-void gts_graph_traverse_destroy (GtsGraphTraverse * t)
-{
-  g_return_if_fail (t != NULL);
-
-  gts_fifo_destroy (t->q);
-  g_free (t);
-}
-
-static void edge_foreach_node (GtsGNode * n, gpointer * info)
-{
-  GtsFunc func = (GtsFunc) info[0];
-  gpointer data = info[1];
-  GHashTable * hash = info[2];
-  GSList * i = GTS_SLIST_CONTAINER (n)->items;
-
-  while (i) {
-    GtsGEdge * e = i->data;
-    if (!g_hash_table_lookup (hash, e)) {
-      (* func) (e, data);
-      g_hash_table_insert (hash, e, e);
-    }
-    i = i->next;
-  }  
-}
-
-/**
- * gts_graph_foreach_edge:
- * @g: a #GtsGraph.
- * @func: a #GtsFunc.
- * @data: user data to be passed to @func.
- *
- * Calls @func for each #GtsEdge of @g.
- */
-void gts_graph_foreach_edge (GtsGraph * g, GtsFunc func, gpointer data)
-{
-  gpointer info[3];
-  GHashTable * hash;
-
-  g_return_if_fail (g != NULL);
-  g_return_if_fail (func != NULL);
-
-  info[0] = func;
-  info[1] = data;
-  info[2] = hash = g_hash_table_new (NULL, NULL);
-  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) edge_foreach_node, info);
-  g_hash_table_destroy (hash);
-}
-
-/**
- * gts_graph_weight:
- * @g: a #GtsGraph.
- *
- * Returns: the weight of graph @g as defined by the weight() method
- * of #GtsGraphClass. 
- */
-gfloat gts_graph_weight (GtsGraph * g)
-{
-  g_return_val_if_fail (g != NULL, 0.);
-
-  if (GTS_GRAPH_CLASS (GTS_OBJECT (g)->klass)->weight)
-    return (* GTS_GRAPH_CLASS (GTS_OBJECT (g)->klass)->weight) (g);
-  return (gfloat) gts_container_size (GTS_CONTAINER (g));
-}
-
-/**
- * gts_graph_distance_sum:
- * @g: a #GtsGraph.
- * @center: a #GtsGNode of @g.
- *
- * Returns: the sum of the distances between all the other #GtsGNode
- * of @g and @center.  
- */
-guint gts_graph_distance_sum (GtsGraph * g, GtsGNode * center)
-{
-  GtsGraphTraverse * t;
-  GtsGNode * n;
-  guint sum = 0;
-
-  g_return_val_if_fail (g != NULL, 0);
-  g_return_val_if_fail (center != NULL, 0);
-
-  t = gts_graph_traverse_new (g, center, GTS_BREADTH_FIRST, TRUE);
-  while ((n = gts_graph_traverse_next (t)))
-    sum += n->level - 1;
-  gts_graph_traverse_destroy (t);
-
-  return sum;
-}
-
-/**
- * gts_graph_farthest:
- * @g: a #GtsGraph.
- * @gnodes: a list of #GtsGNode belonging to @g.
- *
- * Returns: the #GtsGNode belonging to @g and farthest from all the nodes in
- * @gnodes (hmmm, definition of "farthest"?).
- */
-GtsGNode * gts_graph_farthest (GtsGraph * g, GSList * gnodes)
-{
-  GtsGNode * farthest = NULL;
-  GSList * i;
-  gboolean reinit = TRUE, changed = TRUE;
-  guint level = 1;
-
-  g_return_val_if_fail (g != NULL, NULL);
-
-  /* initialize traversals */
-  i = gnodes;
-  while (i) {
-    GTS_OBJECT (i->data)->reserved = 
-      gts_graph_traverse_new (g, i->data, GTS_BREADTH_FIRST, reinit);
-    reinit = FALSE;
-    i = i->next;
-  }
-
-  while (changed) {
-    changed = FALSE;
-    i = gnodes;
-    while (i) {
-      GtsGraphTraverse * t = GTS_OBJECT (i->data)->reserved;
-      GtsGNode * n;
-      while ((n = gts_graph_traverse_what_next (t)) && n->level == level) {
-	changed = TRUE;
-	farthest = n;
-	gts_graph_traverse_next (t);
-      }
-      i = i->next;
-    }
-    level++;
-  }
-
-  /* destroy traversals */
-  i = gnodes;
-  while (i) {
-    gts_graph_traverse_destroy (GTS_OBJECT (i->data)->reserved);
-    GTS_OBJECT (i->data)->reserved = NULL;
-    i = i->next;
-  }
-  return farthest;
-}
-
-static void neighbor_count (GtsGNode * n, gpointer * data)
-{
-  guint * cuts = data[0];
-  GtsGraph * g = data[1];
-  
-  if (!gts_containee_is_contained (GTS_CONTAINEE (n), GTS_CONTAINER (g)))
-    (*cuts)++;
-}
-
-static void count_edge_cuts (GtsGNode * n, gpointer * data)
-{
-  gts_gnode_foreach_neighbor (n, NULL, (GtsFunc) neighbor_count, data);
-}
-
-/**
- * gts_graph_edges_cut:
- * @g: a #GtsGraph.
- *
- * Returns: the number of edges of @g connecting nodes belonging to @g
- * to nodes not belonging to @g.  
- */
-guint gts_graph_edges_cut (GtsGraph * g)
-{
-  guint cuts = 0;
-  gpointer data[2];
-
-  g_return_val_if_fail (g != NULL, 0);
-
-  data[0] = &cuts;
-  data[1] = g;
-  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) count_edge_cuts, data);
-
-  return cuts;
-}
-
-static void sum_edge_cuts_weight (GtsGNode * n, gpointer * data)
-{
-  gfloat * weight = data[0];
-  GtsGraph * g = data[1];
-  GSList * i = GTS_SLIST_CONTAINER (n)->items;
-
-  while (i) {
-    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
-    if (!gts_containee_is_contained (GTS_CONTAINEE (n1), GTS_CONTAINER (g)))
-      *weight += gts_gedge_weight (i->data);
-    i = i->next;
-  }
-}
-
-/**
- * gts_graph_edges_cut_weight:
- * @g: a #GtsGraph.
- *
- * Returns: the sum of the weights of the edges of @g connecting nodes
- * belonging to @g to nodes not belonging to @g.
- */
-gfloat gts_graph_edges_cut_weight (GtsGraph * g)
-{
-  gfloat weight = 0.;
-  gpointer data[2];
-
-  g_return_val_if_fail (g != NULL, 0);
-
-  data[0] = &weight;
-  data[1] = g;
-  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) sum_edge_cuts_weight, 
-			 data);
-
-  return weight;
-}
-
-/**
- * gts_graph_read_jostle:
- * @g: a #GtsGraph.
- * @fp: a #GtsFile.
- *
- * Adds to @g the nodes and edges defined in the file pointed to by
- * @fp. This file must use the Jostle "graph" ASCII format.  
- * The nodes created are of type #GtsNGNode and their identities are the
- * line number at which they appear in @fp.
- *
- * Returns: 0 if the lecture was successful, the line number at which
- * an error occured otherwise (in which case the @error field of @fp
- * is set).  
- */
-guint gts_graph_read_jostle (GtsGraph * g, GtsFile * fp)
-{
-  guint nn, ne, n;
-  GtsGNode ** nodes;
-
-  g_return_val_if_fail (g != NULL, 1);
-  g_return_val_if_fail (fp != NULL, 1);
-
-  if (fp->type != GTS_INT) {
-    gts_file_error (fp, "expecting an integer (number of nodes)");
-    return fp->line;
-  }
-  nn = atoi (fp->token->str);
-  gts_file_next_token (fp);
-
-  if (fp->type != GTS_INT) {
-    gts_file_error (fp, "expecting an integer (number of edges)");
-    return fp->line;
-  }
-  ne = atoi (fp->token->str);
-
-  gts_file_first_token_after (fp, '\n');
-  nodes = g_malloc (sizeof (GtsGNode *)*(nn + 1));
-
-  n = 0;
-  while (n < nn && fp->type != GTS_ERROR) {
-    GtsNGNode * node = gts_ngnode_new (gts_ngnode_class (), fp->line);
-    
-    nodes[n++] = GTS_GNODE (node);
-    gts_container_add (GTS_CONTAINER (g), GTS_CONTAINEE (node));
-    do {
-      if (fp->type != GTS_INT)
-	gts_file_error (fp, "expecting an integer (node index)");
-      else {
-	guint in = atoi (fp->token->str);
-	
-	if (in == 0 || in > nn)
-	  gts_file_error (fp, "node index `%d' is out of range `[1,%d]'",
-			  in, nn);
-	else if (in == n)
-	  gts_file_error (fp, "node index `%d' references itself", in);
-	else if (in < n) {
-	  gts_gedge_new (g->edge_class, GTS_GNODE (node), nodes[in - 1]);
-	  ne--;
-	  gts_file_next_token (fp);
-	}
-      }
-    } while (fp->type != GTS_ERROR && fp->type != '\n');
-  }
-  g_free (nodes);
-
-  if (fp->type != GTS_ERROR) {
-    if (n != nn)
-      gts_file_error (fp, "only `%d' nodes read out of `%d'",
-		      n, nn);
-    else if (ne > 0)
-      gts_file_error (fp, "`%d' unallocated edges remaining",
-		      ne);
-  }
-
-  if (fp->type == GTS_ERROR)
-    return fp->line;
-  return 0;
-}
-
-static void count_edges (GtsGEdge * e, guint * nedge)
-{
-  (*nedge)++;
-}
-
-static void write_node (GtsObject * node, gpointer * data)
-{
-  FILE * fp = data[0];
-  guint * nnode = data[1];
-
-  node->reserved = GUINT_TO_POINTER ((*nnode)++);
-  if (node->klass->write)
-    (* node->klass->write) (node, fp);
-  fputc ('\n', fp);
-}
-
-static void write_edge (GtsGEdge * edge, FILE * fp)
-{
-  fprintf (fp, "%u %u", 
-	   GPOINTER_TO_UINT (GTS_OBJECT (edge->n1)->reserved),
-	   GPOINTER_TO_UINT (GTS_OBJECT (edge->n2)->reserved));
-  if (GTS_OBJECT (edge)->klass->write)
-    (* GTS_OBJECT (edge)->klass->write) (GTS_OBJECT (edge), fp);
-  fputc ('\n', fp);
-}
-
-/**
- * gts_graph_write:
- * @g: a #GtsGraph.
- * @fp: a file pointer.
- *
- * Writes in the file @fp an ASCII representation of @g. The file
- * format is as follows. 
- *
- * All the lines beginning with #GTS_COMMENTS are ignored. The first line
- * contains two unsigned integers separated by spaces. The first
- * integer is the number of nodes, nn, the second is the number of
- * edges, ne.
- *
- * Follows nn lines containing node description.
- * Follows ne lines containing the two indices (starting
- * from one) of the nodes of each edge.
- *
- * The format described above is the least common denominator to all
- * GTS files.  Consistent with an object-oriented approach, the GTS
- * file format is extensible. Each of the lines of the file can be
- * extended with user-specific attributes accessible through the
- * read() and write() virtual methods of each of the objects written
- * (graph, nodes or edges). When read with different object classes,
- * these extra attributes are just ignored.  
- */
-void gts_graph_write (GtsGraph * g, FILE * fp)
-{
-  guint nnode = 1, nedge = 0;
-  gpointer data[2];
-
-  g_return_if_fail (g != NULL);
-  g_return_if_fail (fp != NULL);
-
-  gts_graph_foreach_edge (g, (GtsFunc) count_edges, &nedge);
-  fprintf (fp, "%u %u", gts_container_size (GTS_CONTAINER (g)), nedge);
-  if (GTS_OBJECT (g)->klass->write)
-    (* GTS_OBJECT (g)->klass->write) (GTS_OBJECT (g), fp);
-  fputc ('\n', fp);
-  data[0] = fp;
-  data[1] = &nnode;
-  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) write_node, data);
-  gts_graph_foreach_edge (g, (GtsFunc) write_edge, fp);
-  gts_container_foreach (GTS_CONTAINER (g), 
-			 (GtsFunc) gts_object_reset_reserved, NULL);
-}
-
-/**
- * gts_graph_read:
- * @fp: a #GtsFile.
- *
- * Reads a graph from a file.
- *
- * Returns: the new #GtsGraph or %NULL if an error occured (in which
- * case the @error field of @fp is set).
- */
-GtsGraph * gts_graph_read (GtsFile * fp)
-{
-  GtsGraph * g;
-  GtsGNode ** nodes;
-  guint nn, ne, n;
-
-  g_return_val_if_fail (fp != NULL, NULL);
-
-  if (fp->type != GTS_INT) {
-    gts_file_error (fp, "expecting an integer (number of nodes)");
-    return NULL;
-  }
-  nn = atoi (fp->token->str);
-  gts_file_next_token (fp);
-
-  if (fp->type != GTS_INT) {
-    gts_file_error (fp, "expecting an integer (number of edges)");
-    return NULL;
-  }
-  ne = atoi (fp->token->str);
-
-  gts_file_next_token (fp);
-  if (fp->type != '\n') {
-    GtsObjectClass * klass;
-
-    gts_graph_class ();
-    gts_gnode_class ();
-    gts_gedge_class ();
-
-    if (fp->type != GTS_STRING) {
-      gts_file_error (fp, "expecting a string (GtsGraphClass)");
-      return NULL;
-    }
-    klass = gts_object_class_from_name (fp->token->str);
-    if (klass == NULL) {
-      gts_file_error (fp, "unknown class `%s'", fp->token->str);
-      return NULL;
-    }
-    if (!gts_object_class_is_from_class (klass, gts_graph_class ())) {
-      gts_file_error (fp, "class `%s' is not a GtsGraphClass", fp->token->str);
-      return NULL;
-    }
-    g = GTS_GRAPH (gts_object_new (klass));
-    g->graph_class = GTS_GRAPH_CLASS (klass);
-    gts_file_next_token (fp);
-    (* klass->read) ((GtsObject **) &g, fp);
-    if (fp->type == GTS_ERROR) {
-      gts_object_destroy (GTS_OBJECT (g));
-      return NULL;
-    }
-  }
-  else
-    g = GTS_GRAPH (gts_object_new (GTS_OBJECT_CLASS (gts_graph_class ())));
-  gts_file_first_token_after (fp, '\n');
-  if (nn <= 0)
-    return g;
-
-  nodes = g_malloc ((nn + 1)*sizeof (GtsGNode *));
-
-  n = 0;
-  while (n < nn && fp->type != GTS_ERROR) {
-    GtsObject * new_node = 
-      gts_object_new (GTS_OBJECT_CLASS (g->node_class));
-
-    gts_container_add (GTS_CONTAINER (g), GTS_CONTAINEE (new_node));
-    if (GTS_OBJECT_CLASS (g->node_class)->read)
-      (*GTS_OBJECT_CLASS (g->node_class)->read) (&new_node, fp);
-    gts_file_first_token_after (fp, '\n');
-    nodes[n++] = GTS_GNODE (new_node);
-  }
-  if (fp->type == GTS_ERROR)
-    nn = n;
-
-  n = 0;
-  while (n < ne && fp->type != GTS_ERROR) {
-    guint n1, n2;
-
-    if (fp->type != GTS_INT)
-      gts_file_error (fp, "expecting an integer (first node index)");
-    else {
-      n1 = atoi (fp->token->str);
-      if (n1 == 0 || n1 > nn)
-	gts_file_error (fp, "node index `%d' is out of range `[1,%d]'",
-			n1, nn);
-      else {
-	gts_file_next_token (fp);
-	if (fp->type != GTS_INT)
-	  gts_file_error (fp, "expecting an integer (second node index)");
-	else {
-	  n2 = atoi (fp->token->str);
-	  if (n2 == 0 || n2 > nn)
-	    gts_file_error (fp, "node index `%d' is out of range `[1,%d]'",
-			    n2, nn);
-	  else {
-	    GtsGEdge * new_edge =
-	      gts_gedge_new (g->edge_class, nodes[n1 - 1], nodes [n2 - 1]);
-
-	    gts_file_next_token (fp);
-	    if (fp->type != '\n')
-	      if (GTS_OBJECT_CLASS (g->edge_class)->read)
-		(*GTS_OBJECT_CLASS (g->edge_class)->read)
-		  ((GtsObject **) &new_edge, fp);
-	    gts_file_first_token_after (fp, '\n');
-	    n++;
-	  }
-	}
-      }
-    }
-  }
-
-  if (fp->type == GTS_ERROR) {
-    gts_allow_floating_gnodes = TRUE;
-    while (nn)
-      gts_object_destroy (GTS_OBJECT (nodes[nn-- - 1]));
-    gts_allow_floating_gnodes = FALSE;
-  }
-  g_free (nodes);
-
-  if (fp->type == GTS_ERROR) {
-    gts_object_destroy (GTS_OBJECT (g));
-    return NULL;
-  }
-  return g;
-}
-
-static void write_dot_node (GtsGNode * node, gpointer * data)
-{
-  FILE * fp = data[0];
-  guint * nnode = data[1];
-
-  fprintf (fp, "  n%u", *nnode);
-  if (GTS_GNODE_CLASS (GTS_OBJECT (node)->klass)->write) {
-    fputs (" [", fp);
-    (* GTS_GNODE_CLASS (GTS_OBJECT (node)->klass)->write) (node, fp);
-    fputc (']', fp);
-  }
-  fputs (";\n", fp);
-  GTS_OBJECT (node)->reserved = GUINT_TO_POINTER ((*nnode)++);  
-}
-
-static void write_dot_edge (GtsGEdge * edge, FILE * fp)
-{
-  fprintf (fp, "  n%u -> n%u", 
-	   GPOINTER_TO_UINT (GTS_OBJECT (edge->n1)->reserved),
-	   GPOINTER_TO_UINT (GTS_OBJECT (edge->n2)->reserved));
-  if (GTS_GEDGE_CLASS (GTS_OBJECT (edge)->klass)->write) {
-    fputs (" [", fp);
-    (* GTS_GEDGE_CLASS (GTS_OBJECT (edge)->klass)->write) (edge, fp);
-    fputc (']', fp);
-  }
-  fputs (";\n", fp);
-}
-
-/**
- * gts_graph_write_dot:
- * @g: a #GtsGraph.
- * @fp: a file pointer.
- *
- * Writes in the file @fp an ASCII representation of @g in the dot format of
- * AT&T Bell Labs.
- */
-void gts_graph_write_dot (GtsGraph * g, FILE * fp)
-{
-  guint nnode = 1;
-  gpointer data[2];
-
-  g_return_if_fail (g != NULL);
-  g_return_if_fail (fp != NULL);
-
-  fprintf (fp, "digraph \"%p\" {\n", g);
-  data[0] = fp;
-  data[1] = &nnode;
-  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) write_dot_node, data);
-  gts_graph_foreach_edge (g, (GtsFunc) write_dot_edge, fp);
-  fputs ("}\n", fp);
-
-  gts_container_foreach (GTS_CONTAINER (g), 
-			 (GtsFunc) gts_object_reset_reserved, NULL);
-}
-
-/* GtsWGraph */
-
-static gfloat wgraph_weight (GtsGraph * g)
-{
-  return GTS_WGRAPH (g)->weight;
-}
-
-static void wgraph_add (GtsContainer * g, GtsContainee * n)
-{
-  GtsWGraph * wg = GTS_WGRAPH (g);
-  gfloat w = gts_gnode_weight (GTS_GNODE (n));
-
-  wg->weight += w;
-  
-  (* GTS_CONTAINER_CLASS (GTS_OBJECT_CLASS (gts_wgraph_class ())->parent_class)->add) (g, n);
-}
-
-static void wgraph_remove (GtsContainer * g, GtsContainee * n)
-{
-  GTS_WGRAPH (g)->weight -= gts_gnode_weight (GTS_GNODE (n));
-  
-  (* GTS_CONTAINER_CLASS (GTS_OBJECT_CLASS (gts_wgraph_class ())->parent_class)->remove) (g, n);
-}
-
-static void wgraph_class_init (GtsWGraphClass * klass)
-{
-  GTS_GRAPH_CLASS (klass)->weight = wgraph_weight;
-
-  GTS_CONTAINER_CLASS (klass)->add = wgraph_add;
-  GTS_CONTAINER_CLASS (klass)->remove = wgraph_remove;
-}
-
-static void wgraph_init (GtsWGraph * g)
-{
-  g->weight = 0.;
-}
-
-/**
- * gts_wgraph_class:
- *
- * Returns: the #GtsWGraphClass.
- */
-GtsWGraphClass * gts_wgraph_class (void)
-{
-  static GtsWGraphClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo wgraph_info = {
-      "GtsWGraph",
-      sizeof (GtsWGraph),
-      sizeof (GtsWGraphClass),
-      (GtsObjectClassInitFunc) wgraph_class_init,
-      (GtsObjectInitFunc) wgraph_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_graph_class ()),
-				  &wgraph_info);
-  }
-
-  return klass;
-}
-
-static void weight_max (GtsGNode * n, gfloat * wmax)
-{
-  gfloat w = gts_gnode_weight (n);
-
-  if (w > *wmax)
-    *wmax = w;
-}
-
-/**
- * gts_wgraph_weight_max:
- * @wg: a #GtsWGraph.
- *
- * Returns: the maximum weight of any vertices belonging to @g.
- */
-gfloat gts_wgraph_weight_max (GtsWGraph * wg)
-{
-  gfloat wmax = - G_MAXFLOAT;
-
-  g_return_val_if_fail (wg != NULL, 0.);
-
-  gts_container_foreach (GTS_CONTAINER (wg), (GtsFunc) weight_max, &wmax);
-
-  return wmax;
-}
-
-/* Surface graph */
-
-static void create_node (GtsFace * f, GtsGraph * graph)
-{
-  GtsFNode * fn = gts_fnode_new (gts_fnode_class (), f);
-
-  gts_container_add (GTS_CONTAINER (graph), GTS_CONTAINEE (fn));
-  GTS_OBJECT (f)->reserved = fn;
-}
-
-static void create_edge (GtsEdge * e, GtsSurface * s)
-{
-  GSList * i = e->triangles;
-  
-  while (i) {
-    GtsFace * f = i->data;
-    if (GTS_IS_FACE (f) && gts_face_has_parent_surface (f, s)) {
-      GSList * j = i->next;
-      while (j) {
-	GtsFace * f1 = j->data;
-	if (GTS_IS_FACE (f1) && gts_face_has_parent_surface (f1, s))
-	  gts_pgedge_new (gts_pgedge_class (), 
-			  GTS_OBJECT (f)->reserved,
-			  GTS_OBJECT (f1)->reserved,
-			  e);
-	j = j->next;
-      }
-    }
-    i = i->next;
-  }
-}
-
-/**
- * gts_surface_graph_new:
- * @klass: a #GtsGraphClass.
- * @s: a #GtsSurface.
- *
- * Returns: a new #GtsGraph representing the connectivity of the faces
- * of @s. This graph uses #GtsFGNode as nodes which allows to store
- * the dependencies between nodes and faces of @s.  
- */
-GtsGraph * gts_surface_graph_new (GtsGraphClass * klass,
-				  GtsSurface * s)
-{
-  GtsGraph * graph;
-  
-  g_return_val_if_fail (klass != NULL, NULL);
-  g_return_val_if_fail (s != NULL, NULL);
-
-  graph = GTS_GRAPH (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  gts_surface_foreach_face (s, (GtsFunc) create_node, graph);
-  gts_surface_foreach_edge (s, (GtsFunc) create_edge, s);
-  gts_surface_foreach_face (s, (GtsFunc) gts_object_reset_reserved, NULL);
-
-  return graph;
-}
-
-static void create_segment_edge (GtsSegment * s, GtsGraph * graph)
-{
-  GtsGNode * n1 = GTS_OBJECT (s->v1)->reserved, * n2;
-
-  if (n1 == NULL) {
-    n1 = GTS_GNODE (gts_pnode_new (gts_pnode_class (), s->v1));
-    gts_container_add (GTS_CONTAINER (graph), GTS_CONTAINEE (n1));
-    GTS_OBJECT (s->v1)->reserved = n1;
-  }
-
-  n2 = GTS_OBJECT (s->v2)->reserved;
-  if (n2 == NULL) {
-    n2 = GTS_GNODE (gts_pnode_new (gts_pnode_class (), s->v2));
-    gts_container_add (GTS_CONTAINER (graph), GTS_CONTAINEE (n2));
-    GTS_OBJECT (s->v2)->reserved = n2;
-  }
-  
-  gts_pgedge_new (gts_pgedge_class (), n1, n2, s);
-}
-
-static void reset_reserved (GtsSegment * s)
-{
-  GTS_OBJECT (s->v1)->reserved = GTS_OBJECT (s->v2)->reserved = NULL;
-}
-
-/**
- * gts_segments_graph_new:
- * @klass: a #GtsGraphClass.
- * @segments: a list of #GtsSegment.
- *
- * Returns: a new #GtsGraph representing the connectivity of the segments
- * in @segments.
- */
-GtsGraph * gts_segments_graph_new (GtsGraphClass * klass,
-				   GSList * segments)
-{
-  GtsGraph * graph;
-  
-  g_return_val_if_fail (klass != NULL, NULL);
-
-  graph = GTS_GRAPH (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  g_slist_foreach (segments, (GFunc) create_segment_edge, graph);
-  g_slist_foreach (segments, (GFunc) reset_reserved, NULL);
-
-  return graph;
-}
-
-static void add_to_surface (GtsGNode * n, GtsSurface * s)
-{
-  if (GTS_IS_FNODE (n))
-    gts_surface_add_face (s, GTS_FNODE (n)->f);
-}
-
-/**
- * gts_surface_graph_surface:
- * @surface_graph: a #GtsGraph using #GtsFGNode as nodes.
- * @s: a #GtsSurface.
- *
- * Returns: a new #GtsSurface using the same classes as @s and
- * composed of the faces defined by @surface_graph.
- */
-GtsSurface * gts_surface_graph_surface (GtsGraph * surface_graph,
-					GtsSurface * s)
-{
-  GtsSurface * s1;
-
-  g_return_val_if_fail (surface_graph != NULL, NULL);
-  g_return_val_if_fail (s != NULL, NULL);
-  
-  s1 = gts_surface_new (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass),
-			s->face_class,
-			s->edge_class,
-			s->vertex_class);
-  gts_container_foreach (GTS_CONTAINER (surface_graph), 
-			 (GtsFunc) add_to_surface, s1);
-  return s1;
-}
-
diff --git a/src/gts/gts-private.h b/src/gts/gts-private.h
deleted file mode 100644
index 59246d1..0000000
--- a/src/gts/gts-private.h
+++ /dev/null
@@ -1,37 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#ifndef __GTS_PRIVATE_H__
-#define __GTS_PRIVATE_H__
-
-/* Debugging flags */
-  
-/* #define DEBUG_FUNCTIONS */
-
-#ifdef DEBUG_FUNCTIONS
-/* #define DEBUG_LEAKS */
-#define DEBUG_IDENTITY
-guint id (gpointer p);
-void id_insert (gpointer p);
-void id_remove (gpointer p);
-void gts_write_triangle (GtsTriangle * t, GtsPoint * o, FILE * fptr);
-void gts_write_segment (GtsSegment * s, GtsPoint * o, FILE * fptr);
-#endif /* DEBUG_FUNCTIONS */
-
-#endif /* __GTS_PRIVATE_H__ */
diff --git a/src/gts/gts.h b/src/gts/gts.h
deleted file mode 100644
index 9397230..0000000
--- a/src/gts/gts.h
+++ /dev/null
@@ -1,2577 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#ifndef __GTS_H__
-#define __GTS_H__
-
-#include <stdio.h>
-#include <glib.h>
-
-#define GTS_MAJOR_VERSION 0
-#define GTS_MINOR_VERSION 7
-#define GTS_MICRO_VERSION 6
-
-#ifdef __cplusplus
-extern "C" {
-#endif /* __cplusplus */
-
-/* Added based on glib.h by M J Loehr 01/01/01 */
-/* GTS version.
- * we prefix variable declarations so they can
- * properly get exported in windows dlls.
- */
-#ifdef NATIVE_WIN32
-#  ifdef GTS_COMPILATION
-#    define GTS_C_VAR __declspec(dllexport)
-#  else /* not GTS_COMPILATION */
-#    define GTS_C_VAR extern __declspec(dllimport)
-#  endif /* not GTS_COMPILATION */
-#else /* not NATIVE_WIN32 */
-#  define GTS_C_VAR extern
-#endif /* not NATIVE_WIN32 */
-
-GTS_C_VAR const guint gts_major_version;
-GTS_C_VAR const guint gts_minor_version;
-GTS_C_VAR const guint gts_micro_version;
-GTS_C_VAR const guint gts_interface_age;
-GTS_C_VAR const guint gts_binary_age;
-
-#define GTS_CHECK_VERSION(major,minor,micro)    \
-    (gts_major_version > (major) || \
-    (gts_major_version == (major) && gts_minor_version > (minor)) || \
-    (gts_major_version == (major) && gts_minor_version == (minor) && \
-     gts_micro_version >= (micro)))
-
-#define GTS_COMMENTS  "#!"
-#define GTS_MAINTAINER "popinet@xxxxxxxxxxxxxxxxxxxxx"
-
-
-
-
-void gts_predicates_init();
-
-
-/* Class declarations for base types */
-
-typedef struct _GtsObjectClassInfo     GtsObjectClassInfo;
-typedef struct _GtsObject        GtsObject;
-typedef struct _GtsObjectClass   GtsObjectClass;
-typedef struct _GtsPoint         GtsPoint;
-typedef struct _GtsPointClass    GtsPointClass;
-typedef struct _GtsVertex        GtsVertex;
-typedef struct _GtsVertexClass   GtsVertexClass;
-typedef struct _GtsSegment       GtsSegment;
-typedef struct _GtsSegmentClass  GtsSegmentClass;
-typedef struct _GtsEdge          GtsEdge;
-typedef struct _GtsEdgeClass     GtsEdgeClass;
-typedef struct _GtsTriangle      GtsTriangle;
-typedef struct _GtsTriangleClass GtsTriangleClass;
-typedef struct _GtsFace          GtsFace;
-typedef struct _GtsFaceClass     GtsFaceClass;
-typedef struct _GtsBBox          GtsBBox;
-typedef struct _GtsBBoxClass     GtsBBoxClass;
-typedef struct _GtsSurface       GtsSurface;
-typedef struct _GtsSurfaceClass  GtsSurfaceClass;
-
-typedef void         (*GtsObjectClassInitFunc) (GtsObjectClass * objclass);
-typedef void         (*GtsObjectInitFunc)      (GtsObject * obj);
-typedef void         (*GtsArgSetFunc)          (GtsObject * obj);
-typedef void         (*GtsArgGetFunc)          (GtsObject * obj);
-
-typedef gdouble                  GtsVector[3];
-typedef gdouble                  GtsVector4[4];
-typedef GtsVector4               GtsMatrix;
-/**
- * GtsKeyFunc:
- * @item: A pointer to an item to be stored in the heap.
- * @data: User data passed to gts_eheap_new().
- *
- * Returns: the value of the key for the given item.
- */
-typedef gdouble                  (*GtsKeyFunc)    (gpointer item,
-						   gpointer data);
-typedef enum 
-{ 
-  GTS_OUT = -1,
-  GTS_ON = 0,
-  GTS_IN = 1
-} GtsIntersect;
-
-typedef struct _GtsColor         GtsColor;
-
-struct _GtsColor {
-  gfloat r, g, b;
-};
-
-typedef gint   (*GtsFunc)              (gpointer item,
-					gpointer data);
-
-/* misc.c */
-
-typedef struct _GtsFile GtsFile;
-
-typedef enum {
-  GTS_NONE   = 1 << 8,
-  GTS_INT    = 1 << 9,
-  GTS_UINT   = 1 << 10,
-  GTS_FLOAT  = 1 << 11,
-  GTS_DOUBLE = 1 << 12,
-  GTS_STRING = 1 << 13,
-  GTS_FILE   = 1 << 14,
-  GTS_ERROR  = 1 << 15
-} GtsTokenType;
-
-struct _GtsFile {
-  FILE * fp;
-  gchar * s, * s1;
-  guint line, pos;
-  GString * token;
-  GtsTokenType type;
-  gchar * error;
-
-  guint curline, curpos;
-  guint scope, scope_max;
-  gint next_token;
-  gchar * delimiters;
-  gchar * comments;
-  gchar * tokens;
-};
-
-typedef struct _GtsFileVariable GtsFileVariable;
-
-struct _GtsFileVariable {
-  GtsTokenType type;
-  gchar name[30];
-  gboolean unique;
-  gpointer data;
-  gboolean set;
-  guint line, pos;
-};
-
-
-GtsFile *      gts_file_new               (FILE * fp);
-GtsFile *      gts_file_new_from_string   (const gchar * s);
-void           gts_file_verror            (GtsFile * f,
-					   const gchar * format,
-					   va_list args);
-void           gts_file_error             (GtsFile * f,
-					   const gchar * format,
-					   ...);
-gint           gts_file_getc              (GtsFile * f);
-guint          gts_file_read              (GtsFile * f, 
-					   gpointer ptr, 
-					   guint size, 
-					   guint nmemb);
-gint           gts_file_getc_scope        (GtsFile * f);
-void           gts_file_next_token        (GtsFile * f);
-void           gts_file_first_token_after (GtsFile * f, 
-					   GtsTokenType type);
-void           gts_file_assign_start      (GtsFile * f, 
-					   GtsFileVariable * vars);
-GtsFileVariable * gts_file_assign_next    (GtsFile * f, 
-					   GtsFileVariable * vars);
-void           gts_file_assign_variables  (GtsFile * f, 
-					   GtsFileVariable * vars);
-void           gts_file_variable_error    (GtsFile * f, 
-					   GtsFileVariable * vars,
-					   const gchar * name,
-					   const gchar * format,
-					   ...);
-void           gts_file_destroy           (GtsFile * f);
-
-/* Objects: object.c */
-
-#ifdef GTS_CHECK_CASTS
-#  define GTS_OBJECT_CAST(obj, type, klass) ((type *) gts_object_check_cast (obj, klass))
-#  define GTS_OBJECT_CLASS_CAST(objklass, type, klass) ((type *) gts_object_class_check_cast (objklass, klass))
-#else  /* not GTS_CHECK_CASTS */
-#  define GTS_OBJECT_CAST(obj, type, klass)             ((type *) (obj))
-#  define GTS_OBJECT_CLASS_CAST(objklass, type, klass)  ((type *) (objklass))
-#endif /* not GTS_CHECK_CASTS */
-
-#define GTS_CLASS_NAME_LENGTH 40
-#define GTS_OBJECT(obj)          GTS_OBJECT_CAST (obj,\
-						  GtsObject,\
-						  gts_object_class ())
-#define GTS_OBJECT_CLASS(klass)  GTS_OBJECT_CLASS_CAST (klass,\
-							GtsObjectClass,\
-							gts_object_class())
-#define GTS_IS_OBJECT(obj) (gts_object_is_from_class (obj,\
-						      gts_object_class ()))
-
-typedef enum
-{
-  GTS_DESTROYED         = 1 << 0,
-  GTS_USER_FLAG         = 1 /* user flags start from here */
-} GtsObjectFlags;
-
-#define GTS_OBJECT_FLAGS(obj)             (GTS_OBJECT (obj)->flags)
-#define GTS_OBJECT_DESTROYED(obj)         ((GTS_OBJECT_FLAGS (obj) & GTS_DESTROYED) != 0)
-#define GTS_OBJECT_SET_FLAGS(obj,flag)	  G_STMT_START{ (GTS_OBJECT_FLAGS (obj) |= (flag)); }G_STMT_END
-#define GTS_OBJECT_UNSET_FLAGS(obj,flag)  G_STMT_START{ (GTS_OBJECT_FLAGS (obj) &= ~(flag)); }G_STMT_END
-
-struct _GtsObjectClassInfo {
-  gchar name[GTS_CLASS_NAME_LENGTH];
-  guint object_size;
-  guint class_size;
-  GtsObjectClassInitFunc class_init_func;
-  GtsObjectInitFunc object_init_func;
-  GtsArgSetFunc arg_set_func;
-  GtsArgGetFunc arg_get_func;
-};
-
-struct _GtsObject {
-  GtsObjectClass * klass;
-
-  gpointer reserved;
-  guint32 flags;
-};
-
-struct _GtsObjectClass {
-  GtsObjectClassInfo info;
-  GtsObjectClass * parent_class;
-
-  void        (* clone)      (GtsObject *, GtsObject *);
-  void        (* destroy)    (GtsObject *);
-  void        (* read)       (GtsObject **, GtsFile *);
-  void        (* write)      (GtsObject *, FILE *);
-  GtsColor    (* color)      (GtsObject *);
-  void        (* attributes) (GtsObject *, GtsObject *);
-};
-
-gpointer         gts_object_class_new      (GtsObjectClass * parent_class,
-					    GtsObjectClassInfo * info);
-GtsObjectClass * gts_object_class          (void);
-gpointer         gts_object_check_cast     (gpointer object, 
-					    gpointer klass);
-gpointer         gts_object_class_check_cast (gpointer klass, 
-					      gpointer from);
-
-static inline
-gpointer gts_object_is_from_class (gpointer object,
-				   gpointer klass)
-{
-  GtsObjectClass * c;
-
-  g_return_val_if_fail (klass != NULL, NULL);
-
-  if (object == NULL)
-    return NULL;
-
-  c = ((GtsObject *) object)->klass;
-
-  g_return_val_if_fail (c != NULL, NULL);
-
-  while (c) {
-    if (c == klass)
-      return object;
-    c = c->parent_class;
-  }
-
-  return NULL;
-}
-
-static inline
-gpointer gts_object_class_is_from_class (gpointer klass,
-					 gpointer from)
-{
-  GtsObjectClass * c;
-
-  g_return_val_if_fail (klass != NULL, NULL);
-  g_return_val_if_fail (from != NULL, NULL);
-
-  c = (GtsObjectClass *) klass;
-  while (c) {
-    if (c == from)
-      return klass;
-    c = c->parent_class;
-  }
-
-  return NULL;
-}
-
-GtsObjectClass * gts_object_class_from_name     (const gchar * name);
-
-GtsObject *      gts_object_new                 (GtsObjectClass * klass);
-GtsObject *      gts_object_clone               (GtsObject * object);
-void             gts_object_attributes          (GtsObject * object, 
-						 GtsObject * from);
-void             gts_object_init                (GtsObject * object, 
-						 GtsObjectClass * klass);
-void             gts_object_reset_reserved      (GtsObject * object);
-void             gts_object_destroy             (GtsObject * object);
-void             gts_finalize                   (void);
-
-/* Ranges: surface.c */
-typedef struct _GtsRange               GtsRange;
-
-struct _GtsRange {
-  gdouble min, max, sum, sum2, mean, stddev;
-  guint n;
-};
-
-void gts_range_init         (GtsRange * r);
-void gts_range_reset        (GtsRange * r);
-void gts_range_add_value    (GtsRange * r, 
-			     gdouble val);
-void gts_range_update       (GtsRange * r);
-void gts_range_print        (GtsRange * r, 
-			     FILE * fptr);
-
-/* Points: point.c */
-
-#define GTS_IS_POINT(obj) (gts_object_is_from_class (obj,\
-						     gts_point_class ()))
-#define GTS_POINT(obj)              GTS_OBJECT_CAST (obj,\
-						     GtsPoint,\
-						     gts_point_class ())
-#define GTS_POINT_CLASS(klass)      GTS_OBJECT_CLASS_CAST (klass,\
-							   GtsPointClass,\
-							   gts_point_class ())
-
-struct _GtsPoint {
-  GtsObject object;
-
-  gdouble x, y, z; /* must be contiguous (cast to robust functions) */
-};
-
-struct _GtsPointClass {
-  GtsObjectClass parent_class;
-  gboolean binary;
-};
-
-GtsPointClass * gts_point_class                      (void);
-GtsPoint *    gts_point_new                          (GtsPointClass * klass,
-						      gdouble x, 
-						      gdouble y, 
-						      gdouble z);
-void          gts_point_set                          (GtsPoint * p, 
-						      gdouble x, 
-						      gdouble y, 
-						      gdouble z);
-#define       gts_point_is_in_rectangle(p, p1, p2)   ((p)->x >= (p1)->x &&\
-						      (p)->x <= (p2)->x &&\
-						      (p)->y >= (p1)->y &&\
-						      (p)->y <= (p2)->y &&\
-						      (p)->z >= (p1)->z &&\
-						      (p)->z <= (p2)->z)
-GtsPoint *    gts_segment_triangle_intersection      (GtsSegment * s,
-						      GtsTriangle * t,
-						      gboolean boundary,
-						      GtsPointClass * klass);
-void          gts_point_transform                    (GtsPoint * p, 
-						      GtsMatrix * m);
-gdouble       gts_point_distance                     (GtsPoint * p1,
-						      GtsPoint * p2);
-gdouble       gts_point_distance2                    (GtsPoint * p1,
-						      GtsPoint * p2);
-gdouble       gts_point_orientation_3d               (GtsPoint * p1,
-						      GtsPoint * p2,
-						      GtsPoint * p3,
-						      GtsPoint * p4);
-gint          gts_point_orientation_3d_sos           (GtsPoint * p1,
-						      GtsPoint * p2,
-						      GtsPoint * p3,
-						      GtsPoint * p4);
-GtsIntersect  gts_point_is_in_triangle               (GtsPoint * p,
-						      GtsTriangle * t);
-gdouble       gts_point_in_circle                    (GtsPoint * p, 
-						      GtsPoint * p1,
-						      GtsPoint * p2,
-						      GtsPoint * p3);
-gdouble       gts_point_in_sphere                    (GtsPoint * p, 
-						      GtsPoint * p1,
-						      GtsPoint * p2,
-						      GtsPoint * p3,
-						      GtsPoint * p4);
-gdouble       gts_point_in_triangle_circle           (GtsPoint * p, 
-						      GtsTriangle * t);
-gdouble       gts_point_orientation                  (GtsPoint * p1,
-						      GtsPoint * p2,
-						      GtsPoint * p3);
-gint          gts_point_orientation_sos              (GtsPoint * p1,
-						      GtsPoint * p2,
-						      GtsPoint * p3);
-gdouble       gts_point_segment_distance2            (GtsPoint * p, 
-						      GtsSegment * s);
-gdouble       gts_point_segment_distance             (GtsPoint * p, 
-						      GtsSegment * s);
-void          gts_point_segment_closest              (GtsPoint * p, 
-						      GtsSegment * s,
-						      GtsPoint * closest);
-gdouble       gts_point_triangle_distance2           (GtsPoint * p, 
-						      GtsTriangle * t);
-gdouble       gts_point_triangle_distance            (GtsPoint * p, 
-						      GtsTriangle * t);
-void          gts_point_triangle_closest             (GtsPoint * p,
-						      GtsTriangle * t,
-						      GtsPoint * closest);
-gboolean      gts_point_is_inside_surface            (GtsPoint * p, 
-						      GNode * tree,
-						      gboolean is_open);
-
-/* Vertices: vertex.c */
-
-#define GTS_IS_VERTEX(obj)   (gts_object_is_from_class (obj,\
-							gts_vertex_class ()))
-#define GTS_VERTEX(obj)             GTS_OBJECT_CAST (obj,\
-						     GtsVertex,\
-						     gts_vertex_class ())
-#define GTS_VERTEX_CLASS(klass)     GTS_OBJECT_CLASS_CAST (klass,\
-							   GtsVertexClass,\
-							   gts_vertex_class ())
-struct _GtsVertex {
-  GtsPoint p;
-  
-  GSList * segments;
-};
-
-struct _GtsVertexClass {
-  GtsPointClass parent_class;
-
-  void        (* intersection_attributes) (GtsVertex *, 
-					   GtsObject *, 
-					   GtsObject *);
-};
-
-GTS_C_VAR 
-gboolean      gts_allow_floating_vertices;
-
-GtsVertexClass * gts_vertex_class          (void);
-GtsVertex *   gts_vertex_new               (GtsVertexClass * klass,
-					    gdouble x,
-					    gdouble y,
-					    gdouble z);
-void          gts_vertex_replace           (GtsVertex * v, 
-					    GtsVertex * with);
-gboolean      gts_vertex_is_unattached     (GtsVertex * v);
-GtsSegment *  gts_vertices_are_connected   (GtsVertex * v1,
-					    GtsVertex * v2);
-GSList *      gts_vertex_triangles         (GtsVertex * v,
-					    GSList * list);
-GSList *      gts_vertex_faces             (GtsVertex * v,
-					    GtsSurface * surface,
-					    GSList * list);
-GSList *      gts_vertex_neighbors         (GtsVertex * v, 
-					    GSList * list,
-					    GtsSurface * surface);
-GSList *      gts_vertices_from_segments   (GSList * segments);
-gboolean      gts_vertex_is_boundary       (GtsVertex * v, 
-					    GtsSurface * surface);
-GList *       gts_vertices_merge           (GList * vertices, 
-					    gdouble epsilon,
-					    gboolean (* check) (GtsVertex *, GtsVertex *));
-GSList *      gts_vertex_fan_oriented      (GtsVertex * v, 
-					    GtsSurface * surface);
-guint         gts_vertex_is_contact        (GtsVertex * v, gboolean sever);
-
-/* GtsVertexNormal: Header */
-
-typedef struct _GtsVertexNormal         GtsVertexNormal;
-
-struct _GtsVertexNormal {
-  /*< private >*/
-  GtsVertex parent;
-
-  /*< public >*/
-  GtsVector n;
-};
-
-#define GTS_VERTEX_NORMAL(obj)            GTS_OBJECT_CAST (obj,\
-					         GtsVertexNormal,\
-					         gts_vertex_normal_class ())
-#define GTS_IS_VERTEX_NORMAL(obj)         (gts_object_is_from_class (obj,\
-						 gts_vertex_normal_class ()))
-
-GtsVertexClass * gts_vertex_normal_class  (void);
-
-/* GtsColorVertex: Header */
-
-typedef struct _GtsColorVertex         GtsColorVertex;
-
-struct _GtsColorVertex {
-  /*< private >*/
-  GtsVertex parent;
-
-  /*< public >*/
-  GtsColor c;
-};
-
-#define GTS_COLOR_VERTEX(obj)            GTS_OBJECT_CAST (obj,\
-					         GtsColorVertex,\
-					         gts_color_vertex_class ())
-#define GTS_IS_COLOR_VERTEX(obj)         (gts_object_is_from_class (obj,\
-						 gts_color_vertex_class ()))
-
-GtsVertexClass * gts_color_vertex_class  (void);
-
-/* Segments: segment.c */
-
-#define GTS_IS_SEGMENT(obj) (gts_object_is_from_class (obj,\
-						       gts_segment_class ()))
-#define GTS_SEGMENT(obj)          GTS_OBJECT_CAST (obj,\
-						   GtsSegment,\
-						   gts_segment_class ())
-#define GTS_SEGMENT_CLASS(klass)  GTS_OBJECT_CLASS_CAST (klass,\
-							 GtsSegmentClass,\
-							 gts_segment_class ())
-
-struct _GtsSegment {
-  GtsObject object;
-
-  GtsVertex * v1;
-  GtsVertex * v2;
-};
-
-struct _GtsSegmentClass {
-  GtsObjectClass parent_class;
-};
-
-GtsSegmentClass * gts_segment_class                  (void);
-GtsSegment *  gts_segment_new                        (GtsSegmentClass * klass,
-						      GtsVertex * v1, 
-						      GtsVertex * v2);
-#define       gts_segment_connect(s, e1, e2)         (((s)->v1 == e1 &&\
-                                                       (s)->v2 == e2) || \
-                                                      ((s)->v1 == e2 &&\
-                                                       (s)->v2 == e1))
-#define       gts_segments_are_identical(s1, s2)     (((s1)->v1 == (s2)->v1 &&\
-						       (s1)->v2 == (s2)->v2)\
-						      ||\
-						      ((s1)->v1 == (s2)->v2 &&\
-						       (s1)->v2 == (s2)->v1))
-#define       gts_segments_touch(s1, s2)             ((s1)->v1 == (s2)->v1 ||\
-						      (s1)->v1 == (s2)->v2 ||\
-						      (s1)->v2 == (s2)->v1 ||\
-						      (s1)->v2 == (s2)->v2)
-GtsIntersect  gts_segments_are_intersecting          (GtsSegment * s1,
-						      GtsSegment * s2);
-GtsSegment *  gts_segment_is_duplicate               (GtsSegment * s);
-GtsVertex *   gts_segment_midvertex                  (GtsSegment * s,
-						      GtsVertexClass * klass);
-GSList *      gts_segments_from_vertices             (GSList * vertices);
-gboolean      gts_segment_is_ok                      (GtsSegment * s);
-
-/* Edges: edge.c */
-
-#define GTS_IS_EDGE(obj)  (gts_object_is_from_class (obj,\
-						     gts_edge_class ()))
-#define GTS_EDGE(obj)            GTS_OBJECT_CAST (obj,\
-						  GtsEdge,\
-						  gts_edge_class ())
-#define GTS_EDGE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-							GtsEdgeClass,\
-							gts_edge_class ())
-
-struct _GtsEdge {
-  GtsSegment segment;
-
-  GSList * triangles;
-};
-
-struct _GtsEdgeClass {
-  GtsSegmentClass parent_class;
-};
-
-GTS_C_VAR 
-gboolean      gts_allow_floating_edges;
-
-GtsEdgeClass * gts_edge_class                     (void);
-GtsEdge *     gts_edge_new                        (GtsEdgeClass * klass,
-						   GtsVertex * v1,
-						   GtsVertex * v2);
-/**
- * gts_edge_is_unattached:
- * @s: a #GtsEdge.
- *
- * Evaluates to %TRUE if no triangles uses @s as an edge, %FALSE otherwise.
- */
-#define       gts_edge_is_unattached(s) ((s)->triangles == NULL ? TRUE : FALSE)
-GtsFace *     gts_edge_has_parent_surface         (GtsEdge * e, 
-						   GtsSurface * surface);
-GtsFace *     gts_edge_has_any_parent_surface     (GtsEdge * e);
-GtsFace *     gts_edge_is_boundary                (GtsEdge * e, 
-						   GtsSurface * surface);
-void          gts_edge_replace                    (GtsEdge * e,
-						   GtsEdge * with);
-GSList *      gts_edges_from_vertices             (GSList * vertices,
-						   GtsSurface * parent);
-guint         gts_edge_face_number                (GtsEdge * e,
-						   GtsSurface * s);
-gboolean      gts_edge_collapse_is_valid          (GtsEdge * e);
-gboolean      gts_edge_collapse_creates_fold      (GtsEdge * e, 
-						   GtsVertex * v,
-						   gdouble max);
-GtsEdge *     gts_edge_is_duplicate               (GtsEdge * e);
-GList *       gts_edges_merge                     (GList * edges);
-gboolean      gts_edge_belongs_to_tetrahedron     (GtsEdge * e);
-guint         gts_edge_is_contact                 (GtsEdge * e);
-void          gts_edge_swap                       (GtsEdge * e, 
-						   GtsSurface * s);
-gboolean      gts_edge_manifold_faces             (GtsEdge * e, 
-						   GtsSurface * s,
-						   GtsFace ** f1, 
-						   GtsFace ** f2);
-
-/* Triangles: triangle.c */
-
-#define GTS_IS_TRIANGLE(obj) (gts_object_is_from_class (obj,\
-							gts_triangle_class ()))
-#define GTS_TRIANGLE(obj)         GTS_OBJECT_CAST (obj,\
-						   GtsTriangle,\
-						   gts_triangle_class ())
-#define GTS_TRIANGLE_CLASS(klass) GTS_OBJECT_CLASS_CAST (klass,\
-							 GtsTriangleClass,\
-							 gts_triangle_class ())
-
-struct _GtsTriangle {
-  GtsObject object;
-
-  GtsEdge * e1;
-  GtsEdge * e2;
-  GtsEdge * e3;
-};
-
-struct _GtsTriangleClass {
-  GtsObjectClass parent_class;
-};
-
-GtsTriangleClass * gts_triangle_class        (void);
-void        gts_triangle_set                 (GtsTriangle * triangle, 
-					      GtsEdge * e1, 
-					      GtsEdge * e2,
-					      GtsEdge * e3);
-GtsTriangle * gts_triangle_new               (GtsTriangleClass * klass, 
-					      GtsEdge * e1, 
-					      GtsEdge * e2,
-					      GtsEdge * e3);
-#define     gts_triangle_vertex(t) (GTS_SEGMENT (GTS_TRIANGLE (t)->e1)->v1 ==\
-                                    GTS_SEGMENT (GTS_TRIANGLE (t)->e2)->v1 || \
-                                    GTS_SEGMENT (GTS_TRIANGLE (t)->e1)->v2 ==\
-                                    GTS_SEGMENT (GTS_TRIANGLE (t)->e2)->v1 ? \
-                                    GTS_SEGMENT (GTS_TRIANGLE (t)->e2)->v2 :\
-                                    GTS_SEGMENT (GTS_TRIANGLE (t)->e2)->v1)
-GtsVertex *   gts_triangle_vertex_opposite  (GtsTriangle * t, 
-					     GtsEdge * e);
-GtsEdge *     gts_triangle_edge_opposite    (GtsTriangle * t, 
-					     GtsVertex * v);
-gdouble       gts_triangles_angle           (GtsTriangle * t1,
-					     GtsTriangle * t2);
-gboolean      gts_triangles_are_compatible  (GtsTriangle * t1, 
-					     GtsTriangle * t2,
-					     GtsEdge * e);
-gdouble       gts_triangle_area             (GtsTriangle * t);
-gdouble       gts_triangle_perimeter        (GtsTriangle * t);
-gdouble       gts_triangle_quality          (GtsTriangle * t);
-void          gts_triangle_normal           (GtsTriangle * t, 
-					     gdouble * x, 
-					     gdouble * y, 
-					     gdouble * z);
-gdouble       gts_triangle_orientation      (GtsTriangle * t);
-void          gts_triangle_revert           (GtsTriangle * t);
-GSList *      gts_triangles_from_edges      (GSList * edges);
-void          gts_triangle_vertices_edges   (GtsTriangle * t, 
-					     GtsEdge * e,
-					     GtsVertex ** v1, 
-					     GtsVertex ** v2, 
-					     GtsVertex ** v3,
-					     GtsEdge ** e1,
-					     GtsEdge ** e2,
-					     GtsEdge ** e3);
-GtsTriangle * gts_triangle_enclosing        (GtsTriangleClass * klass,
-					     GSList * points, 
-					     gdouble scale);
-guint         gts_triangle_neighbor_number  (GtsTriangle * t);
-GSList *      gts_triangle_neighbors        (GtsTriangle * t);
-GtsEdge *     gts_triangles_common_edge     (GtsTriangle * t1,
-					     GtsTriangle * t2);
-GtsTriangle * gts_triangle_is_duplicate     (GtsTriangle * t);
-GtsTriangle * gts_triangle_use_edges        (GtsEdge * e1,
-					     GtsEdge * e2,
-					     GtsEdge * e3);
-gboolean      gts_triangle_is_ok            (GtsTriangle * t);
-void          gts_triangle_vertices         (GtsTriangle * t,
-					     GtsVertex ** v1,
-					     GtsVertex ** v2,
-					     GtsVertex ** v3);
-GtsPoint *    gts_triangle_circumcircle_center (GtsTriangle * t,
-						GtsPointClass * point_class);
-gboolean      gts_triangles_are_folded      (GSList * triangles,
-					     GtsVertex * A, GtsVertex * B,
-					     gdouble max);
-GtsObject *   gts_triangle_is_stabbed       (GtsTriangle * t,
-					     GtsPoint * p,
-					     gdouble * orientation);
-void          gts_triangle_interpolate_height (GtsTriangle * t, 
-					       GtsPoint * p);
-
-/* Faces: face.c */
-
-#define GTS_IS_FACE(obj) (gts_object_is_from_class (obj,\
-						    gts_face_class ()))
-#define GTS_FACE(obj)          GTS_OBJECT_CAST (obj,\
-						GtsFace,\
-						gts_face_class ())
-#define GTS_FACE_CLASS(klass)  GTS_OBJECT_CLASS_CAST (klass,\
-						      GtsFaceClass,\
-						      gts_face_class ())
-
-struct _GtsFace {
-  GtsTriangle triangle;
-
-  GSList * surfaces;
-};
-
-struct _GtsFaceClass {
-  GtsTriangleClass parent_class;
-};
-
-GTS_C_VAR 
-gboolean      gts_allow_floating_faces;
-
-GtsFaceClass * gts_face_class                       (void);
-GtsFace *     gts_face_new                          (GtsFaceClass * klass,
-						     GtsEdge * e1,
-						     GtsEdge * e2,
-						     GtsEdge * e3);
-gboolean      gts_face_has_parent_surface           (GtsFace * f,
-						     GtsSurface * s);
-GSList *      gts_faces_from_edges                  (GSList * edges, 
-						     GtsSurface * s);
-guint         gts_face_neighbor_number              (GtsFace * f, 
-						     GtsSurface * s);
-GSList *      gts_face_neighbors                    (GtsFace * f, 
-						     GtsSurface * s);
-void          gts_face_foreach_neighbor             (GtsFace * f, 
-						     GtsSurface * s, 
-						     GtsFunc func,
-						     gpointer data);
-gboolean      gts_face_is_compatible                (GtsFace * f, 
-						     GtsSurface * s);
-
-/* Matrices: matrix.c */
-
-#define       gts_vector_cross(C,A,B) ((C)[0] = (A)[1]*(B)[2] - (A)[2]*(B)[1],\
-			               (C)[1] = (A)[2]*(B)[0] - (A)[0]*(B)[2],\
-			               (C)[2] = (A)[0]*(B)[1] - (A)[1]*(B)[0])
-
-#define       gts_vector_init(v, p1, p2)   ((v)[0] = (p2)->x - (p1)->x,\
-					    (v)[1] = (p2)->y - (p1)->y,\
-					    (v)[2] = (p2)->z - (p1)->z)
-#define       gts_vector_scalar(v1, v2)    ((v1)[0]*(v2)[0] +\
-					    (v1)[1]*(v2)[1] +\
-					    (v1)[2]*(v2)[2])
-#define       gts_vector_norm(v)   (sqrt ((v)[0]*(v)[0] +\
-                                          (v)[1]*(v)[1] +\
-                                          (v)[2]*(v)[2]))
-#define       gts_vector_normalize(v) {\
-  gdouble __gts_n = gts_vector_norm (v);\
-  if (__gts_n > 0.) {\
-    (v)[0] /= __gts_n;\
-    (v)[1] /= __gts_n;\
-    (v)[2] /= __gts_n;\
-  }\
-}
-GtsMatrix * gts_matrix_new (gdouble a00, gdouble a01, gdouble a02, gdouble a03,
-			    gdouble a10, gdouble a11, gdouble a12, gdouble a13,
-			    gdouble a20, gdouble a21, gdouble a22, gdouble a23,
-			    gdouble a30, gdouble a31, gdouble a32, gdouble a33);
-void gts_matrix_assign (GtsMatrix * m,
-			gdouble a00, gdouble a01, gdouble a02, gdouble a03,
-			gdouble a10, gdouble a11, gdouble a12, gdouble a13,
-			gdouble a20, gdouble a21, gdouble a22, gdouble a23,
-			gdouble a30, gdouble a31, gdouble a32, gdouble a33);
-GtsMatrix *   gts_matrix_projection                  (GtsTriangle * t);
-GtsMatrix *   gts_matrix_transpose                   (GtsMatrix * m);
-gdouble       gts_matrix_determinant                 (GtsMatrix * m);
-GtsMatrix *   gts_matrix_inverse                     (GtsMatrix * m);
-GtsMatrix *   gts_matrix3_inverse                    (GtsMatrix * m);
-void          gts_matrix_print                       (GtsMatrix * m, 
-						      FILE * fptr);
-guint         gts_matrix_compatible_row              (GtsMatrix * A,
-						      GtsVector b,
-						      guint n,
-						      GtsVector A1,
-						      gdouble b1);
-guint         gts_matrix_quadratic_optimization      (GtsMatrix * A,
-						      GtsVector b,
-						      guint n,
-						      GtsMatrix * H,
-						      GtsVector c);
-GtsMatrix *   gts_matrix_product                     (GtsMatrix * m1, 
-						      GtsMatrix * m2);
-GtsMatrix *   gts_matrix_zero                        (GtsMatrix * m);
-GtsMatrix *   gts_matrix_identity                    (GtsMatrix * m);
-GtsMatrix *   gts_matrix_scale                       (GtsMatrix * m, 
-						      GtsVector s);
-GtsMatrix *   gts_matrix_translate                   (GtsMatrix * m, 
-						      GtsVector t);
-GtsMatrix *   gts_matrix_rotate                      (GtsMatrix * m,
-						      GtsVector r,
-						      gdouble angle);
-void          gts_matrix_destroy                     (GtsMatrix * m);
-void          gts_vector_print                       (GtsVector v,
-						      FILE * fptr);
-void          gts_vector4_print                      (GtsVector4 v, 
-						      FILE * fptr);
-
-/* Kdtrees: kdtree.c */
-
-#define       gts_kdtree_destroy(tree)               g_node_destroy(tree)
-
-GNode *       gts_kdtree_new                         (GPtrArray * points,
-						      int (*compare)
-						      (const void *, 
-						       const void *));
-GSList *      gts_kdtree_range                       (GNode * tree,
-						      GtsBBox * bbox,
-						      int (*compare)
-						      (const void *, 
-						      const void *));
-
-/* Bboxtrees: bbtree.c */
-
-/**
- * GtsBBTreeTraverseFunc:
- * @bb1: a #GtsBBox.
- * @bb2: another #GtsBBox.
- * @data: user data passed to the function.
- *
- * User function called for each pair of overlapping bounding
- * boxes. See gts_bb_tree_traverse_overlapping().
- */
-typedef void   (*GtsBBTreeTraverseFunc)          (GtsBBox * bb1,
-						  GtsBBox * bb2,
-						  gpointer data);
-/**
- * GtsBBoxDistFunc:
- * @p: a #GtsPoint.
- * @bounded: an object bounded by a #GtsBBox.
- *
- * User function returning the (minimum) distance between the object
- * defined by @bounded and point @p.
- *
- * Returns: the distance between @p and @bounded.
- */
-typedef gdouble (*GtsBBoxDistFunc)               (GtsPoint * p,
-						  gpointer bounded);
-/**
- * GtsBBoxClosestFunc:
- * @p: a #GtsPoint.
- * @bounded: an object bounded by a #GtsBBox.
- * 
- * User function returning a #GtsPoint belonging to the object defined
- * by @bounded and closest to @p.
- *
- * Returns: a #GtsPoint.
- */
-typedef GtsPoint * (*GtsBBoxClosestFunc)         (GtsPoint * p,
-						  gpointer bounded);
-
-/**
- * GTS_IS_BBOX:
- * @obj: a #GtsObject.
- *
- * Evaluates to %TRUE if @obj is a #GtsBBox, %FALSE otherwise.
- */
-#define GTS_IS_BBOX(obj)  (gts_object_is_from_class (obj,\
-						     gts_bbox_class ()))
-/**
- * GTS_BBOX:
- * @obj: a #GtsObject.
- *
- * Casts @obj to #GtsBBox.
- */
-#define GTS_BBOX(obj)         GTS_OBJECT_CAST (obj,\
-					       GtsBBox,\
-					       gts_bbox_class ())
-/**
- * GTS_BBOX_CLASS:
- * @klass: a descendant of #GtsBBoxClass.
- *
- * Casts @klass to #GtsBBoxClass.
- */
-#define GTS_BBOX_CLASS(klass) GTS_OBJECT_CLASS_CAST (klass,\
-						     GtsBBoxClass,\
-						     gts_bbox_class ())
-
-struct _GtsBBox {
-  GtsObject object;
-  gpointer bounded;
-  gdouble x1, y1, z1;
-  gdouble x2, y2, z2;
-};
-
-struct _GtsBBoxClass {
-  GtsObjectClass parent_class;
-};
-
-GtsBBoxClass * gts_bbox_class                (void);
-GtsBBox *  gts_bbox_new                      (GtsBBoxClass * klass,
-					      gpointer bounded,
-					      gdouble x1, 
-					      gdouble y1, 
-					      gdouble z1,
-					      gdouble x2, 
-					      gdouble y2, 
-					      gdouble z2);
-void       gts_bbox_set                      (GtsBBox * bbox,
-					      gpointer bounded,
-					      gdouble x1, 
-					      gdouble y1, 
-					      gdouble z1,
-					      gdouble x2, 
-					      gdouble y2, 
-					      gdouble z2);
-GtsBBox *  gts_bbox_segment                  (GtsBBoxClass * klass,
-					      GtsSegment * s);
-GtsBBox *  gts_bbox_triangle                 (GtsBBoxClass * klass,
-					      GtsTriangle * t);
-GtsBBox *  gts_bbox_surface                  (GtsBBoxClass * klass, 
-					      GtsSurface * surface);
-GtsBBox *  gts_bbox_bboxes                   (GtsBBoxClass * klass,
-					      GSList * bboxes);
-GtsBBox *  gts_bbox_points                   (GtsBBoxClass * klass,
-					      GSList * points);
-/**
- * gts_bbox_point_is_inside:
- * @bbox: a #GtsBBox.
- * @p: a #GtsPoint.
- *
- * Evaluates to %TRUE if @p is inside (or on the boundary) of @bbox, %FALSE otherwise.
- */
-#define    gts_bbox_point_is_inside(bbox, p) ((p)->x >= (bbox)->x1 &&\
-					     (p)->y >= (bbox)->y1 &&\
-                                             (p)->z >= (bbox)->z1 &&\
-                                             (p)->x <= (bbox)->x2 &&\
-					     (p)->y <= (bbox)->y2 &&\
-                                             (p)->z <= (bbox)->z2)
-gboolean   gts_bboxes_are_overlapping        (GtsBBox * bb1, 
-					      GtsBBox * bb2);
-void       gts_bbox_draw                     (GtsBBox * bb, 
-					      FILE * fptr);
-gdouble    gts_bbox_diagonal2                (GtsBBox * bb);
-void       gts_bbox_point_distance2          (GtsBBox * bb, 
-					      GtsPoint * p,
-					      gdouble * min,
-					      gdouble * max);
-gboolean   gts_bbox_is_stabbed               (GtsBBox * bb, 
-					      GtsPoint * p);
-gboolean   gts_bbox_overlaps_triangle        (GtsBBox * bb,
-					      GtsTriangle * t);
-gboolean   gts_bbox_overlaps_segment         (GtsBBox * bb, 
-					      GtsSegment * s);
-
-GNode *    gts_bb_tree_new                   (GSList * bboxes);
-GNode *    gts_bb_tree_surface               (GtsSurface * s);
-GSList *   gts_bb_tree_stabbed               (GNode * tree, 
-					      GtsPoint * p);
-GSList *   gts_bb_tree_overlap               (GNode * tree, 
-					      GtsBBox * bbox);
-gboolean   gts_bb_tree_is_overlapping        (GNode * tree, 
-					      GtsBBox * bbox);
-void       gts_bb_tree_traverse_overlapping  (GNode * tree1, 
-					      GNode * tree2,
-					      GtsBBTreeTraverseFunc func,
-					      gpointer data);
-void       gts_bb_tree_draw                  (GNode * tree, 
-					      guint depth, 
-					      FILE * fptr);
-GSList *   gts_bb_tree_point_closest_bboxes  (GNode * tree, 
-					      GtsPoint * p);
-gdouble    gts_bb_tree_point_distance        (GNode * tree, 
-					      GtsPoint * p,
-					      GtsBBoxDistFunc distance,
-					      GtsBBox ** bbox);
-GtsPoint * gts_bb_tree_point_closest         (GNode * tree, 
-					      GtsPoint * p,
-					      GtsBBoxClosestFunc closest,
-					      gdouble * distance);
-void       gts_bb_tree_segment_distance      (GNode * tree, 
-					      GtsSegment * s,
-					      GtsBBoxDistFunc distance,
-					      gdouble delta,
-					      GtsRange * range);
-void       gts_bb_tree_triangle_distance     (GNode * tree, 
-					      GtsTriangle * t,
-					      GtsBBoxDistFunc distance,
-					      gdouble delta,
-					      GtsRange * range);
-void       gts_bb_tree_surface_distance      (GNode * tree,
-					      GtsSurface * s,
-					      GtsBBoxDistFunc distance,
-					      gdouble delta,
-					      GtsRange * range);
-void       gts_bb_tree_surface_boundary_distance 
-                                             (GNode * tree,
-					      GtsSurface * s,
-					      GtsBBoxDistFunc distance,
-					      gdouble delta,
-					      GtsRange * range);
-void       gts_bb_tree_destroy               (GNode * tree, 
-					      gboolean free_leaves);
-
-/* Surfaces: surface.c */
-
-typedef struct _GtsSurfaceStats        GtsSurfaceStats;
-typedef struct _GtsSurfaceQualityStats GtsSurfaceQualityStats;
-typedef GtsVertex * (*GtsRefineFunc)   (GtsEdge * e,
-					GtsVertexClass * klass,
-					gpointer data);
-typedef GtsVertex * (*GtsCoarsenFunc)  (GtsEdge * e,
-					GtsVertexClass * klass,
-					gpointer data);
-typedef gboolean    (*GtsStopFunc)     (gdouble cost,
-					guint nedge,
-					gpointer data);
-
-struct _GtsSurfaceStats {
-  guint n_faces;
-  guint n_incompatible_faces;
-  guint n_duplicate_faces;
-  guint n_duplicate_edges;
-  guint n_boundary_edges;
-  guint n_non_manifold_edges;
-  GtsRange edges_per_vertex, faces_per_edge;
-  GtsSurface * parent;
-};
-
-struct _GtsSurfaceQualityStats {
-  GtsRange face_quality;
-  GtsRange face_area;
-  GtsRange edge_length;
-  GtsRange edge_angle;
-  GtsSurface * parent;
-};
-
-struct _GtsSurface {
-  GtsObject object;
-
-#ifdef USE_SURFACE_BTREE
-  GTree * faces;
-#else /* not USE_SURFACE_BTREE */
-  GHashTable * faces;
-#endif /* not USE_SURFACE_BTREE */
-  GtsFaceClass * face_class;
-  GtsEdgeClass * edge_class;
-  GtsVertexClass * vertex_class;
-  gboolean keep_faces;
-};
-
-struct _GtsSurfaceClass {
-  GtsObjectClass parent_class;
-
-  void (* add_face)    (GtsSurface *, GtsFace *);
-  void (* remove_face) (GtsSurface *, GtsFace *);
-};
-
-#define GTS_IS_SURFACE(obj) (gts_object_is_from_class (obj,\
-						       gts_surface_class ()))
-#define GTS_SURFACE(obj)         GTS_OBJECT_CAST (obj,\
-						  GtsSurface,\
-						  gts_surface_class ())
-#define GTS_SURFACE_CLASS(klass) GTS_OBJECT_CLASS_CAST (klass,\
-							GtsSurfaceClass,\
-							gts_surface_class ())
-
-GtsSurfaceClass * gts_surface_class        (void);
-GtsSurface * gts_surface_new               (GtsSurfaceClass * klass,
-					    GtsFaceClass * face_class,
-					    GtsEdgeClass * edge_class,
-					    GtsVertexClass * vertex_class);
-void         gts_surface_add_face          (GtsSurface * s, 
-					    GtsFace * f);
-void         gts_surface_remove_face       (GtsSurface * s, 
-					    GtsFace * f);
-guint        gts_surface_read              (GtsSurface * surface,
-					    GtsFile * f);
-gdouble      gts_surface_area              (GtsSurface * s);
-void         gts_surface_stats             (GtsSurface * s, 
-					    GtsSurfaceStats * stats);
-void         gts_surface_quality_stats     (GtsSurface * s, 
-					    GtsSurfaceQualityStats * stats);
-void         gts_surface_print_stats       (GtsSurface * s, 
-					    FILE * fptr);
-void         gts_surface_write             (GtsSurface * s, 
-					    FILE * fptr);
-void         gts_surface_write_oogl        (GtsSurface * s, 
-					    FILE * fptr);
-void         gts_surface_write_vtk         (GtsSurface * s, 
-					    FILE * fptr);
-void         gts_surface_write_oogl_boundary (GtsSurface * s, 
-					      FILE * fptr);
-void         gts_surface_foreach_vertex    (GtsSurface * s, 
-					    GtsFunc func, 
-					    gpointer data);
-void         gts_surface_foreach_edge      (GtsSurface * s, 
-					    GtsFunc func, 
-					    gpointer data);
-void         gts_surface_foreach_face      (GtsSurface * s,
-					    GtsFunc func, 
-					    gpointer data);
-guint        gts_surface_foreach_face_remove (GtsSurface * s,
-					      GtsFunc func, 
-					      gpointer data);
-typedef struct _GtsSurfaceTraverse GtsSurfaceTraverse;
-GtsSurfaceTraverse * gts_surface_traverse_new (GtsSurface * s,
-					       GtsFace * f);
-GtsFace *    gts_surface_traverse_next     (GtsSurfaceTraverse * t,
-					    guint * level);
-void         gts_surface_traverse_destroy  (GtsSurfaceTraverse * t);
-void         gts_surface_refine            (GtsSurface * surface,
-					    GtsKeyFunc cost_func,
-					    gpointer cost_data,
-					    GtsRefineFunc refine_func,
-					    gpointer refine_data,
-					    GtsStopFunc stop_func,
-					    gpointer stop_data);
-gboolean     gts_edge_collapse_is_valid    (GtsEdge * e);
-void         gts_surface_coarsen           (GtsSurface * surface,
-					    GtsKeyFunc cost_func,
-					    gpointer cost_data,
-					    GtsCoarsenFunc coarsen_func,
-					    gpointer coarsen_data,
-					    GtsStopFunc stop_func,
-					    gpointer stop_data,
-					    gdouble minangle);
-gboolean     gts_coarsen_stop_number       (gdouble cost, 
-					    guint nedge, 
-					    guint * min_number);
-gboolean     gts_coarsen_stop_cost         (gdouble cost, 
-					    guint nedge, 
-					    gdouble * max_cost);
-void         gts_surface_tessellate        (GtsSurface * s,
-					    GtsRefineFunc refine_func,
-					    gpointer refine_data);
-GtsSurface * gts_surface_generate_sphere   (GtsSurface * s,
-					    guint geodesation_order);
-GtsSurface * gts_surface_copy              (GtsSurface * s1,
-					    GtsSurface * s2);
-void         gts_surface_merge             (GtsSurface * s, 
-					    GtsSurface * with);
-gboolean     gts_surface_is_manifold       (GtsSurface * s);
-gboolean     gts_surface_is_closed         (GtsSurface * s);
-gboolean     gts_surface_is_orientable     (GtsSurface * s);
-gdouble      gts_surface_volume            (GtsSurface * s);
-gdouble      gts_surface_center_of_mass    (GtsSurface * s,
-					    GtsVector cm);
-gdouble      gts_surface_center_of_area    (GtsSurface * s,
-					    GtsVector cm);
-guint        gts_surface_vertex_number     (GtsSurface * s);
-guint        gts_surface_edge_number       (GtsSurface * s);
-guint        gts_surface_face_number       (GtsSurface * s);
-void         gts_surface_distance          (GtsSurface * s1, 
-					    GtsSurface * s2, 
-					    gdouble delta,
-					    GtsRange * face_range, 
-					    GtsRange * boundary_range);
-GSList *     gts_surface_boundary          (GtsSurface * surface);
-GSList *     gts_surface_split             (GtsSurface * s);
-
-/* Discrete differential operators: curvature.c */
-
-gboolean gts_vertex_mean_curvature_normal  (GtsVertex * v, 
-					    GtsSurface * s, 
-					    GtsVector Kh);
-gboolean gts_vertex_gaussian_curvature     (GtsVertex * v, 
-					    GtsSurface * s, 
-					    gdouble * Kg);
-void     gts_vertex_principal_curvatures   (gdouble Kh, 
-					    gdouble Kg, 
-					    gdouble * K1, 
-					    gdouble * K2);
-void     gts_vertex_principal_directions   (GtsVertex * v, 
-					    GtsSurface * s, 
-					    GtsVector Kh,
-                                            gdouble Kg,
-					    GtsVector e1, 
-					    GtsVector e2);
-
-/* Volume optimization: vopt.c */
-typedef struct _GtsVolumeOptimizedParams   GtsVolumeOptimizedParams;
-
-struct _GtsVolumeOptimizedParams {
-  gdouble volume_weight;
-  gdouble boundary_weight;
-  gdouble shape_weight;
-};
-
-GtsVertex *  gts_volume_optimized_vertex   (GtsEdge * edge,
-					    GtsVertexClass * klass,
-					    GtsVolumeOptimizedParams * params);
-gdouble      gts_volume_optimized_cost     (GtsEdge * e,
-					    GtsVolumeOptimizedParams * params);
-
-/* bool operations: boolean.c */
-
-GSList *     gts_surface_intersection      (GtsSurface * s1,
-					    GtsSurface * s2,
-					    GNode * faces_tree1,
-					    GNode * faces_tree2);
-
-typedef struct _GtsSurfaceInter         GtsSurfaceInter;
-typedef struct _GtsSurfaceInterClass    GtsSurfaceInterClass;
-/**
- * GtsBooleanOperation:
- * @GTS_1_OUT_2: identifies the part of the first surface which lies
- * outside the second surface.
- * @GTS_1_IN_2: identifies the part of the first surface which lies
- * inside the second surface.
- * @GTS_2_OUT_1: identifies the part of the second surface which lies
- * outside the first surface.
- * @GTS_2_IN_1: identifies the part of the second surface which lies
- * inside the first surface.
- */
-typedef enum { GTS_1_OUT_2, 
-	       GTS_1_IN_2, 
-	       GTS_2_OUT_1, 
-	       GTS_2_IN_1 }             GtsBooleanOperation;
-
-/**
- * GTS_IS_SURFACE_INTER:
- * @obj: a #GtsObject.
- *
- * Evaluates to %TRUE if @obj is a #GtsSurfaceInter, %FALSE otherwise.
- */
-#define GTS_IS_SURFACE_INTER(obj) (gts_object_is_from_class (obj,\
-					      gts_surface_inter_class ()))
-/**
- * GTS_SURFACE_INTER:
- * @obj: a descendant of #GtsSurfaceInter.
- *
- * Casts @obj to #GtsSurfaceInter.
- */
-#define GTS_SURFACE_INTER(obj)         GTS_OBJECT_CAST (obj,\
-						  GtsSurfaceInter,\
-						  gts_surface_inter_class ())
-/**
- * GTS_SURFACE_INTER_CLASS:
- * @klass: a descendant of #GtsSurfaceInterClass.
- *
- * Casts @klass to #GtsSurfaceInterClass.
- */
-#define GTS_SURFACE_INTER_CLASS(klass) GTS_OBJECT_CLASS_CAST (klass,\
-						 GtsSurfaceInterClass,\
-						 gts_surface_inter_class ())
-
-struct _GtsSurfaceInter {
-  GtsObject object;
-
-  GtsSurface * s1;
-  GtsSurface * s2;
-  GSList * edges;
-};
-
-struct _GtsSurfaceInterClass {
-  GtsObjectClass parent_class;
-};
-
-GtsSurfaceInterClass *
-gts_surface_inter_class          (void);
-GtsSurfaceInter *
-gts_surface_inter_new            (GtsSurfaceInterClass * klass,
-				  GtsSurface * s1,
-				  GtsSurface * s2,
-				  GNode * faces_tree1,
-				  GNode * faces_tree2,
-				  gboolean is_open1,
-				  gboolean is_open2);
-gboolean 
-gts_surface_inter_check          (GtsSurfaceInter * si,
-				  gboolean * closed);
-void 
-gts_surface_inter_boolean        (GtsSurfaceInter * si, 
-				  GtsSurface * surface,
-				  GtsBooleanOperation op);
-gboolean gts_surface_foreach_intersecting_face (GtsSurface * s,
-					    GtsBBTreeTraverseFunc func,
-					    gpointer data);
-GtsSurface * 
-gts_surface_is_self_intersecting (GtsSurface * s);
-
-/* Binary Heap: heap.c */
-
-typedef struct _GtsHeap         GtsHeap;
-
-GtsHeap *    gts_heap_new          (GCompareFunc compare_func);
-void         gts_heap_insert       (GtsHeap * heap, gpointer p);
-gpointer     gts_heap_remove_top   (GtsHeap * heap);
-gpointer     gts_heap_top          (GtsHeap * heap);
-void         gts_heap_thaw         (GtsHeap * heap);
-void         gts_heap_foreach      (GtsHeap * heap, 
-				    GFunc func,
-				    gpointer user_data);
-void         gts_heap_freeze       (GtsHeap * heap);
-guint        gts_heap_size         (GtsHeap * heap);
-void         gts_heap_destroy      (GtsHeap * heap);
-
-/* Extended Binary Heap: eheap.c */
-
-typedef struct _GtsEHeap         GtsEHeap;
-typedef struct _GtsEHeapPair     GtsEHeapPair;
-
-struct _GtsEHeap {
-  GPtrArray * elts;
-  GtsKeyFunc func;
-  gpointer data;
-  gboolean frozen, randomized;
-};
-
-/**
- * _GtsEHeapPair:
- * @data: Points to the item stored in the heap.
- * @key: Value of the key for this item.
- * @pos: Private field.
- */
-struct _GtsEHeapPair {
-  gpointer data;
-  gdouble key;
-  guint pos;
-};
-
-GtsEHeap *     gts_eheap_new          (GtsKeyFunc key_func,
-				       gpointer data);
-GtsEHeapPair * gts_eheap_insert       (GtsEHeap * heap, 
-				       gpointer p);
-GtsEHeapPair * gts_eheap_insert_with_key (GtsEHeap * heap, 
-					  gpointer p, 
-					  gdouble key);
-gpointer       gts_eheap_remove_top   (GtsEHeap * heap,
-				       gdouble * key);
-gpointer       gts_eheap_top          (GtsEHeap * heap, 
-				       gdouble * key);
-void           gts_eheap_thaw         (GtsEHeap * heap);
-void           gts_eheap_foreach      (GtsEHeap * heap, 
-				       GFunc func,
-				       gpointer data);
-gpointer       gts_eheap_remove       (GtsEHeap * heap, 
-				       GtsEHeapPair * p);
-void           gts_eheap_decrease_key (GtsEHeap * heap,
-				       GtsEHeapPair * p,
-				       gdouble new_key);
-void           gts_eheap_freeze       (GtsEHeap * heap);
-guint          gts_eheap_size         (GtsEHeap * heap);
-void           gts_eheap_update       (GtsEHeap * heap);
-gdouble        gts_eheap_key          (GtsEHeap * heap,
-				       gpointer p);
-void           gts_eheap_randomized   (GtsEHeap * heap, 
-				       gboolean randomized);
-void           gts_eheap_destroy      (GtsEHeap * heap);
-
-/* FIFO queues: fifo.c */
-
-typedef struct _GtsFifo GtsFifo;
-
-GtsFifo *      gts_fifo_new           (void);
-void           gts_fifo_write         (GtsFifo * fifo, 
-				       FILE * fp);
-void           gts_fifo_push          (GtsFifo * fifo, 
-				       gpointer data);
-gpointer       gts_fifo_pop           (GtsFifo * fifo);
-gpointer       gts_fifo_top           (GtsFifo * fifo);
-guint          gts_fifo_size          (GtsFifo * fifo);
-gboolean       gts_fifo_is_empty      (GtsFifo * fifo);
-void           gts_fifo_foreach       (GtsFifo * fifo, 
-				       GtsFunc func, 
-				       gpointer data);
-void           gts_fifo_reverse       (GtsFifo * fifo);
-void           gts_fifo_destroy       (GtsFifo * fifo);
-
-/* Progressive surfaces */
-
-/* split.c */
-
-typedef struct _GtsSplit      GtsSplit;
-typedef struct _GtsSplitClass GtsSplitClass;
-typedef struct _GtsSplitCFace GtsSplitCFace;
-
-struct _GtsSplit {
-  GtsObject object;
-
-  GtsVertex * v;
-  GtsObject * v1;
-  GtsObject * v2;
-  GtsSplitCFace * cfaces;
-  guint ncf;
-};
-
-struct _GtsSplitClass {
-  GtsObjectClass parent_class;
-};
-
-#define GTS_IS_SPLIT(obj)    (gts_object_is_from_class (obj,\
-							gts_split_class ()))
-#define GTS_SPLIT(obj)              GTS_OBJECT_CAST (obj,\
-						     GtsSplit,\
-						     gts_split_class ())
-#define GTS_SPLIT_CLASS(klass)      GTS_OBJECT_CLASS_CAST (klass,\
-						     GtsSplitClass,\
-						     gts_split_class ())
-#define GTS_SPLIT_V1(vs)            (GTS_IS_SPLIT ((vs)->v1) ?\
-				     GTS_SPLIT ((vs)->v1)->v :\
-				     GTS_VERTEX ((vs)->v1))
-#define GTS_SPLIT_V2(vs)            (GTS_IS_SPLIT ((vs)->v2) ?\
-				     GTS_SPLIT ((vs)->v2)->v :\
-				     GTS_VERTEX ((vs)->v2))
-
-GtsSplitClass *  gts_split_class          (void);
-GtsSplit *       gts_split_new            (GtsSplitClass * klass,
-					   GtsVertex * v,
-					   GtsObject * o1,
-					   GtsObject * o2);
-void             gts_split_collapse       (GtsSplit * vs,
-					   GtsEdgeClass * klass,
-					   GtsEHeap * heap);
-void             gts_split_expand         (GtsSplit * vs, 
-					   GtsSurface * s,
-					   GtsEdgeClass * klass);
-typedef gboolean (*GtsSplitTraverseFunc)  (GtsSplit * vs,
-					   gpointer data);
-void             gts_split_traverse       (GtsSplit * root,
-					   GTraverseType        order,
-					   gint                 depth,
-					   GtsSplitTraverseFunc func,
-					   gpointer             data);
-guint            gts_split_height         (GtsSplit * root);
-
-/* psurface.c */
-
-typedef struct _GtsPSurface         GtsPSurface;
-typedef struct _GtsPSurfaceClass    GtsPSurfaceClass;
-
-struct _GtsPSurface {
-  GtsObject object;
-
-  GtsSurface * s;
-  GPtrArray * split;
-  GtsSplitClass * split_class;
-  guint pos, min;
-
-  GPtrArray * vertices;
-  GPtrArray * faces;
-};
-
-struct _GtsPSurfaceClass {
-  GtsObjectClass parent_class;
-};
-
-#define GTS_IS_PSURFACE(obj) (gts_object_is_from_class (obj,\
-							gts_psurface_class ()))
-#define GTS_PSURFACE(obj)           GTS_OBJECT_CAST (obj,\
-						     GtsPSurface,\
-						     gts_psurface_class ())
-#define GTS_PSURFACE_CLASS(klass)     GTS_OBJECT_CLASS_CAST (klass,\
-						     GtsPSurfaceClass,\
-						     gts_psurface_class ())
-#define GTS_PSURFACE_IS_CLOSED(ps)  (!(ps)->vertices)
-
-GtsPSurfaceClass * gts_psurface_class         (void);
-GtsPSurface * gts_psurface_new                (GtsPSurfaceClass * klass,
-					       GtsSurface * surface,
-					       GtsSplitClass * split_class,
-					       GtsKeyFunc cost_func,
-					       gpointer cost_data,
-					       GtsCoarsenFunc coarsen_func,
-					       gpointer coarsen_data,
-					       GtsStopFunc stop_func,
-					       gpointer stop_data,
-					       gdouble minangle);
-GtsSplit *    gts_psurface_add_vertex         (GtsPSurface * ps);
-GtsSplit *    gts_psurface_remove_vertex      (GtsPSurface * ps);
-guint         gts_psurface_max_vertex_number  (GtsPSurface * ps);
-guint         gts_psurface_min_vertex_number  (GtsPSurface * ps);
-void          gts_psurface_set_vertex_number  (GtsPSurface * ps, 
-					       guint n);
-guint         gts_psurface_get_vertex_number  (GtsPSurface * ps);
-void          gts_psurface_write              (GtsPSurface * ps,
-					       FILE * fptr);
-GtsPSurface * gts_psurface_open               (GtsPSurfaceClass * klass,
-					       GtsSurface * s,
-					       GtsSplitClass * split_class,
-					       GtsFile * f);
-GtsSplit *    gts_psurface_read_vertex        (GtsPSurface * ps, 
-					       GtsFile * fp);
-void          gts_psurface_close              (GtsPSurface * ps);
-void          gts_psurface_foreach_vertex     (GtsPSurface * ps, 
-					       GtsFunc func, 
-					       gpointer data);
-
-/* hsurface.c */
-
-typedef struct _GtsHSplit        GtsHSplit;
-typedef struct _GtsHSplitClass   GtsHSplitClass;
-typedef struct _GtsHSurface      GtsHSurface;
-typedef struct _GtsHSurfaceClass GtsHSurfaceClass;
-
-struct _GtsHSplit {
-  GtsSplit split;
-
-  GtsEHeapPair * index;
-  GtsHSplit * parent;
-  guint nchild;
-};
-
-struct _GtsHSplitClass {
-  GtsSplitClass parent_class;
-};
-
-#define GTS_IS_HSPLIT(obj) (gts_object_is_from_class (obj,\
-						      gts_hsplit_class ()))
-#define GTS_HSPLIT(obj)           GTS_OBJECT_CAST (obj,\
-						   GtsHSplit,\
-						   gts_hsplit_class ())
-#define GTS_HSPLIT_CLASS(klass)     GTS_OBJECT_CLASS_CAST (klass,\
-						   GtsHSplitClass,\
-						   gts_hsplit_class ())
-
-GtsHSplitClass * gts_hsplit_class             (void);
-GtsHSplit *   gts_hsplit_new                  (GtsHSplitClass * klass, 
-					       GtsSplit * vs);
-void          gts_hsplit_collapse             (GtsHSplit * hs,
-					       GtsHSurface * hsurface);
-void          gts_hsplit_expand               (GtsHSplit * hs,
-					       GtsHSurface * hsurface);
-void          gts_hsplit_force_expand         (GtsHSplit * hs,
-					       GtsHSurface * hsurface);
-
-struct _GtsHSurface {
-  GtsObject object;
-
-  GtsSurface * s;
-  GSList * roots;
-  GtsEHeap * expandable;
-  GtsEHeap * collapsable;
-  GPtrArray * split;
-  guint nvertex;
-};
-
-struct _GtsHSurfaceClass {
-  GtsObjectClass parent_class;
-};
-
-#define GTS_IS_HSURFACE(obj) (gts_object_is_from_class (obj,\
-							gts_hsurface_class ()))
-#define GTS_HSURFACE(obj)           GTS_OBJECT_CAST (obj,\
-						     GtsHSurface,\
-						     gts_hsurface_class ())
-#define GTS_HSURFACE_CLASS(klass)   GTS_OBJECT_CLASS_CAST (klass,\
-						     GtsHSurfaceClass,\
-						     gts_hsurface_class ())
-
-GtsHSurfaceClass * gts_hsurface_class    (void);
-GtsHSurface * gts_hsurface_new           (GtsHSurfaceClass * klass,
-					  GtsHSplitClass *   hsplit_class,
-					  GtsPSurface *      psurface,
-					  GtsKeyFunc         expand_key,
-					  gpointer           expand_data,
-					  GtsKeyFunc         collapse_key,
-					  gpointer           collapse_data);
-void          gts_hsurface_traverse      (GtsHSurface *        hsurface,
-					  GTraverseType        order,
-					  gint                 depth,
-					  GtsSplitTraverseFunc func,
-					  gpointer             data);
-void          gts_hsurface_foreach       (GtsHSurface *        hsurface,
-					  GTraverseType        order,
-					  GtsFunc              func,
-					  gpointer             data);
-guint         gts_hsurface_height        (GtsHSurface *        hsurface);
-
-/* Constrained Delaunay triangulation: cdt.c */
-
-/**
- * GTS_IS_CONSTRAINT:
- * @obj: a #GtsObject.
- *
- * Evaluates to %TRUE if @obj is a #GtsConstraint, %FALSE otherwise.
- */
-#define GTS_IS_CONSTRAINT(obj)      (gts_object_is_from_class (obj,\
-						    gts_constraint_class ()))
-/**
- * GTS_CONSTRAINT:
- * @obj: a descendant of #GtsConstraint.
- *
- * Casts @obj to #GtsConstraint.
- */
-#define GTS_CONSTRAINT(obj)          GTS_OBJECT_CAST (obj,\
-						  GtsConstraint,\
-						  gts_constraint_class ())
-/**
- * GTS_CONSTRAINT_CLASS:
- * @klass: a desscendant of #GtsConstraintClass.
- *
- * Casts @klass to #GtsConstraintClass.
- */
-#define GTS_CONSTRAINT_CLASS(klass)  GTS_OBJECT_CLASS_CAST (klass,\
-						  GtsConstraintClass,\
-						  gts_constraint_class ())
-
-struct _GtsConstraint {
-  GtsEdge edge;
-};
-
-struct _GtsConstraintClass {
-  GtsEdgeClass parent_class;
-};
-
-typedef struct _GtsConstraint        GtsConstraint;
-typedef struct _GtsConstraintClass   GtsConstraintClass;
-
-GtsConstraintClass * gts_constraint_class        (void);
-
-GtsFace *            gts_point_locate            (GtsPoint * p, 
-						  GtsSurface * surface,
-						  GtsFace * guess);
-GtsVertex *          gts_delaunay_add_vertex_to_face (GtsSurface * surface, 
-						      GtsVertex * v,
-						      GtsFace * f);
-GtsVertex *          gts_delaunay_add_vertex     (GtsSurface * surface, 
-						  GtsVertex * v,
-						  GtsFace * guess);
-void                 gts_delaunay_remove_vertex  (GtsSurface * surface, 
-						  GtsVertex * v);
-GtsFace *            gts_delaunay_check          (GtsSurface * surface);
-GSList *             gts_delaunay_add_constraint (GtsSurface * surface,
-						  GtsConstraint * c);
-void                 gts_delaunay_remove_hull    (GtsSurface * surface);
-
-/* GtsListFace: Header */
-
-typedef struct _GtsListFace         GtsListFace;
-
-struct _GtsListFace {
-  /*< private >*/
-  GtsFace parent;
-
-  /*< public >*/
-  GSList * points;
-};
-
-#define GTS_LIST_FACE(obj)            GTS_OBJECT_CAST (obj,\
-					         GtsListFace,\
-					         gts_list_face_class ())
-#define GTS_IS_LIST_FACE(obj)         (gts_object_is_from_class (obj,\
-						 gts_list_face_class ()))
-
-GtsFaceClass *       gts_list_face_class         (void);
-
-/* Constrained Delaunay refinement: refine.c */
-
-typedef gboolean   (* GtsEncroachFunc)           (GtsVertex * v,
-						  GtsEdge * e,
-						  GtsSurface * s,
-						  gpointer data);
-
-gboolean             gts_vertex_encroaches_edge  (GtsVertex * v, 
-						  GtsEdge * e);
-GtsVertex *          gts_edge_is_encroached      (GtsEdge * e,
-						  GtsSurface * s,
-						  GtsEncroachFunc encroaches,
-						  gpointer data);
-guint                gts_delaunay_conform        (GtsSurface * surface,
-						  gint steiner_max,
-						  GtsEncroachFunc encroaches,
-						  gpointer data);
-guint                gts_delaunay_refine         (GtsSurface * surface,
-						  gint steiner_max,
-						  GtsEncroachFunc encroaches,
-						  gpointer encroach_data,
-						  GtsKeyFunc cost,
-						  gpointer cost_data);
-
-/* Isosurfaces (marching cubes): iso.c */
-
-typedef struct _GtsGridPlane     GtsGridPlane;
-typedef struct _GtsIsoSlice      GtsIsoSlice;
-typedef struct _GtsCartesianGrid GtsCartesianGrid;
-
-struct _GtsGridPlane {
-  GtsPoint ** p;
-  guint nx, ny;
-};
-
-struct _GtsCartesianGrid {
-  guint nx, ny, nz;
-  gdouble x, dx, y, dy, z, dz;
-};
-
-typedef void (*GtsIsoCartesianFunc)         (gdouble ** a,
-					     GtsCartesianGrid g,
-					     guint i,
-					     gpointer data);
-
-GtsGridPlane * gts_grid_plane_new           (guint nx, 
-					     guint ny);
-void           gts_grid_plane_destroy       (GtsGridPlane * g);
-GtsIsoSlice *  gts_iso_slice_new            (guint nx, guint ny);
-void           gts_iso_slice_fill           (GtsIsoSlice * slice,
-					     GtsGridPlane * plane1,
-					     GtsGridPlane * plane2,
-					     gdouble ** f1,
-					     gdouble ** f2,
-					     gdouble iso,
-					     GtsVertexClass * klass);
-void           gts_iso_slice_fill_cartesian (GtsIsoSlice * slice,
-					     GtsCartesianGrid g,
-					     gdouble ** f1,
-					     gdouble ** f2,
-					     gdouble iso,
-					     GtsVertexClass * klass);
-void           gts_iso_slice_destroy        (GtsIsoSlice * slice);
-void           gts_isosurface_slice         (GtsIsoSlice * slice1,
-					     GtsIsoSlice * slice2,
-					     GtsSurface * surface);
-void           gts_isosurface_cartesian     (GtsSurface * surface,
-					     GtsCartesianGrid g,
-					     GtsIsoCartesianFunc f,
-					     gpointer data,
-					     gdouble iso);
-
-/* Isosurfaces (marching tetrahedra): isotetra.c */
-
-void           gts_isosurface_tetra         (GtsSurface * surface,
-					     GtsCartesianGrid g,
-					     GtsIsoCartesianFunc f,
-					     gpointer data,
-					     gdouble iso);
-void           gts_isosurface_tetra_bcl     (GtsSurface * surface,
-					     GtsCartesianGrid g,
-					     GtsIsoCartesianFunc f,
-					     gpointer data,
-					     gdouble iso);
-void           gts_isosurface_tetra_bounded (GtsSurface * surface,
-					     GtsCartesianGrid g,
-					     GtsIsoCartesianFunc f,
-					     gpointer data,
-					     gdouble iso);
-
-/* Named vertices, edges and triangles: named.c */
-
-#define GTS_NAME_LENGTH             40
-
-#define GTS_NVERTEX(obj)            GTS_OBJECT_CAST (obj,\
-						     GtsNVertex,\
-						     gts_nvertex_class ())
-#define GTS_NVERTEX_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-							   GtsNVertexClass,\
-							   gts_nvertex_class())
-#define GTS_IS_NVERTEX(obj)         (gts_object_is_from_class (obj,\
-				       gts_nvertex_class ()))
-
-typedef struct _GtsNVertex          GtsNVertex;
-typedef struct _GtsNVertexClass     GtsNVertexClass;
-
-struct _GtsNVertex {
-  GtsVertex parent;
-  char name[GTS_NAME_LENGTH];
-};
-
-struct _GtsNVertexClass {
-  GtsVertexClass parent_class;
-};
-
-GtsNVertexClass * gts_nvertex_class        (void);
-
-#define GTS_NEDGE(obj)            GTS_OBJECT_CAST (obj,\
-						   GtsNEdge,\
-						   gts_nedge_class ())
-#define GTS_NEDGE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-							 GtsNEdgeClass,\
-							 gts_nedge_class())
-#define GTS_IS_NEDGE(obj)         (gts_object_is_from_class (obj,\
-				       gts_nedge_class ()))
-
-typedef struct _GtsNEdge          GtsNEdge;
-typedef struct _GtsNEdgeClass     GtsNEdgeClass;
-
-struct _GtsNEdge {
-  GtsEdge parent;
-  char name[GTS_NAME_LENGTH];
-};
-
-struct _GtsNEdgeClass {
-  GtsEdgeClass parent_class;
-};
-
-GtsNEdgeClass *   gts_nedge_class        (void);
-
-#define GTS_NFACE(obj)            GTS_OBJECT_CAST (obj,\
-						   GtsNFace,\
-						   gts_nface_class ())
-#define GTS_NFACE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-							 GtsNFaceClass,\
-							 gts_nface_class())
-#define GTS_IS_NFACE(obj)         (gts_object_is_from_class (obj,\
-				       gts_nface_class ()))
-
-typedef struct _GtsNFace          GtsNFace;
-typedef struct _GtsNFaceClass     GtsNFaceClass;
-
-struct _GtsNFace {
-  GtsFace parent;
-  char name[GTS_NAME_LENGTH];
-};
-
-struct _GtsNFaceClass {
-  GtsFaceClass parent_class;
-};
-
-GtsNFaceClass *       gts_nface_class        (void);
-
-/* Cluster object for out-of-core simplification: oocs.c */
-
-#define GTS_CLUSTER(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsCluster,\
-					           gts_cluster_class ())
-#define GTS_CLUSTER_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsClusterClass,\
-						         gts_cluster_class())
-#define GTS_IS_CLUSTER(obj)         (gts_object_is_from_class (obj,\
-						   gts_cluster_class ()))
-     
-typedef struct _GtsCluster         GtsCluster;
-typedef struct _GtsClusterClass    GtsClusterClass;
-typedef struct _GtsClusterId       GtsClusterId;
-
-struct _GtsClusterId {
-  guint x, y, z;
-};
-
-struct _GtsCluster {
-  GtsObject parent;
-
-  GtsClusterId id;
-  GtsVertex * v;
-  guint n;
-};
-
-struct _GtsClusterClass {
-  GtsObjectClass parent_class;
-
-  void (* add) (GtsCluster * c, GtsPoint * p, gpointer data);
-  void (* update) (GtsCluster * c);
-};
-
-GtsClusterClass * gts_cluster_class                (void);
-GtsCluster *      gts_cluster_new                  (GtsClusterClass * klass,
-						    GtsClusterId id,
-						    GtsVertexClass * vklass);
-void              gts_cluster_add                  (GtsCluster * c, 
-						    GtsPoint * p,
-						    gpointer data);
-void              gts_cluster_update               (GtsCluster * c);
-
-/* Cluster group object for out-of-core simplification: oocs.c */
-
-#define GTS_CLUSTER_GRID(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsClusterGrid,\
-					           gts_cluster_grid_class ())
-#define GTS_CLUSTER_GRID_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						   GtsClusterGridClass,\
-						   gts_cluster_grid_class())
-#define GTS_IS_CLUSTER_GRID(obj)         (gts_object_is_from_class (obj,\
-						   gts_cluster_grid_class ()))
-     
-typedef struct _GtsClusterGrid         GtsClusterGrid;
-typedef struct _GtsClusterGridClass    GtsClusterGridClass;
-
-struct _GtsClusterGrid {
-  GtsObject parent;
-
-  GtsSurface * surface;
-  GtsBBox * bbox;
-  GtsVector size;
-
-  GtsClusterClass * cluster_class;
-  GHashTable * clusters;
-};
-
-struct _GtsClusterGridClass {
-  GtsObjectClass parent_class;
-};
-
-GtsClusterGridClass * gts_cluster_grid_class (void);
-GtsClusterGrid *      gts_cluster_grid_new   (GtsClusterGridClass * klass,
-					      GtsClusterClass * cluster_class,
-					      GtsSurface * s,
-					      GtsBBox * bbox,
-					      gdouble delta);
-void           gts_cluster_grid_add_triangle (GtsClusterGrid * cluster_grid,
-					      GtsPoint * p1,
-					      GtsPoint * p2,
-					      GtsPoint * p3,
-					      gpointer data);
-GtsRange       gts_cluster_grid_update       (GtsClusterGrid * cluster_grid);
-
-/* Triangle strip generation: stripe.c */
-GSList *       gts_surface_strip             (GtsSurface * s);
-
-/* GtsContainee: container.c */
-
-typedef struct _GtsContainee         GtsContainee;
-typedef struct _GtsContaineeClass    GtsContaineeClass;
-typedef struct _GtsContainer         GtsContainer;
-typedef struct _GtsContainerClass    GtsContainerClass;
-
-struct _GtsContainee {
-  GtsObject object;
-};
-
-struct _GtsContaineeClass {
-  GtsObjectClass parent_class;
-
-  void     (* add_container)    (GtsContainee *, GtsContainer *);
-  void     (* remove_container) (GtsContainee *, GtsContainer *);
-  void     (* foreach)          (GtsContainee *, GtsFunc, gpointer);
-  gboolean (* is_contained)     (GtsContainee *, GtsContainer *);
-  void     (* replace)          (GtsContainee *, GtsContainee *);
-};
-
-#define GTS_CONTAINEE(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsContainee,\
-					           gts_containee_class ())
-#define GTS_CONTAINEE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsContaineeClass,\
-						         gts_containee_class())
-#define GTS_IS_CONTAINEE(obj)         (gts_object_is_from_class (obj,\
-						   gts_containee_class ()))
-     
-GtsContaineeClass * gts_containee_class        (void);
-GtsContainee *      gts_containee_new          (GtsContaineeClass * klass);
-gboolean            gts_containee_is_contained (GtsContainee * item, 
-						GtsContainer * c);
-void                gts_containee_replace      (GtsContainee * item,
-						GtsContainee * with);
-
-/* GtsSListContainee: container.c */
-
-typedef struct _GtsSListContainee         GtsSListContainee;
-typedef struct _GtsSListContaineeClass    GtsSListContaineeClass;
-
-struct _GtsSListContainee {
-  GtsContainee containee;
-
-  GSList * containers;
-};
-
-struct _GtsSListContaineeClass {
-  GtsContaineeClass parent_class;
-};
-
-#define GTS_SLIST_CONTAINEE(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsSListContainee,\
-					           gts_slist_containee_class ())
-#define GTS_SLIST_CONTAINEE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsSListContaineeClass,\
-						         gts_slist_containee_class())
-#define GTS_IS_SLIST_CONTAINEE(obj)         (gts_object_is_from_class (obj,\
-						   gts_slist_containee_class ()))
-     
-GtsSListContaineeClass * gts_slist_containee_class   (void);
-
-/* GtsContainer: container.c */
-
-struct _GtsContainer {
-  GtsSListContainee object;
-};
-
-struct _GtsContainerClass {
-  GtsSListContaineeClass parent_class;
-
-  void  (* add)     (GtsContainer *, GtsContainee *);
-  void  (* remove)  (GtsContainer *, GtsContainee *);
-  void  (* foreach) (GtsContainer *, GtsFunc, gpointer);
-  guint (* size)    (GtsContainer *);
-};
-
-#define GTS_CONTAINER(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsContainer,\
-					           gts_container_class ())
-#define GTS_CONTAINER_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsContainerClass,\
-						         gts_container_class())
-#define GTS_IS_CONTAINER(obj)         (gts_object_is_from_class (obj,\
-						   gts_container_class ()))
-     
-GtsContainerClass * gts_container_class     (void);
-GtsContainer *      gts_container_new       (GtsContainerClass * klass);
-void                gts_container_add       (GtsContainer * c,
-					     GtsContainee * item);
-void                gts_container_remove    (GtsContainer * c,
-					     GtsContainee * item);
-void                gts_container_foreach   (GtsContainer * c,
-					     GtsFunc func,
-					     gpointer data);
-guint               gts_container_size      (GtsContainer * c);
-
-/* GtsHashContainer: container.c */
-
-typedef struct _GtsHashContainer         GtsHashContainer;
-typedef struct _GtsHashContainerClass    GtsHashContainerClass;
-
-struct _GtsHashContainer {
-  GtsContainer c;
-
-  GHashTable * items;
-  gboolean frozen;
-};
-
-struct _GtsHashContainerClass {
-  GtsContainerClass parent_class;
-};
-
-#define GTS_HASH_CONTAINER(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsHashContainer,\
-					           gts_hash_container_class ())
-#define GTS_HASH_CONTAINER_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsHashContainerClass,\
-						         gts_hash_container_class())
-#define GTS_IS_HASH_CONTAINER(obj)         (gts_object_is_from_class (obj,\
-						   gts_hash_container_class ()))
-     
-GtsHashContainerClass * gts_hash_container_class (void);
-
-/* GtsSListContainer: container.c */
-
-typedef struct _GtsSListContainer         GtsSListContainer;
-typedef struct _GtsSListContainerClass    GtsSListContainerClass;
-
-struct _GtsSListContainer {
-  GtsContainer c;
-
-  GSList * items;
-  gboolean frozen;
-};
-
-struct _GtsSListContainerClass {
-  GtsContainerClass parent_class;
-};
-
-#define GTS_SLIST_CONTAINER(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsSListContainer,\
-					           gts_slist_container_class ())
-#define GTS_SLIST_CONTAINER_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsSListContainerClass,\
-						         gts_slist_container_class())
-#define GTS_IS_SLIST_CONTAINER(obj)         (gts_object_is_from_class (obj,\
-						   gts_slist_container_class ()))
-     
-GtsSListContainerClass * gts_slist_container_class (void);
-
-/* GtsGNode: graph.c */
-
-typedef struct _GtsGNode         GtsGNode;
-typedef struct _GtsGNodeClass    GtsGNodeClass;
-typedef struct _GtsGraph         GtsGraph;
-typedef struct _GtsGraphClass    GtsGraphClass;
-
-struct _GtsGNode {
-  GtsSListContainer container;
-
-  guint level;
-};
-
-struct _GtsGNodeClass {
-  GtsSListContainerClass parent_class;
-
-  gfloat (* weight) (GtsGNode *);
-  void   (* write)  (GtsGNode *, FILE *);
-};
-
-#define GTS_GNODE(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsGNode,\
-					           gts_gnode_class ())
-#define GTS_GNODE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsGNodeClass,\
-						         gts_gnode_class())
-#define GTS_IS_GNODE(obj)         (gts_object_is_from_class (obj,\
-						   gts_gnode_class ()))
-#define GTS_GNODE_NEIGHBOR(n,e)   (GTS_GEDGE (e)->n1 == n ? GTS_GEDGE (e)->n2 : GTS_GEDGE (e)->n2 == n ? GTS_GEDGE (e)->n1 : NULL)
-     
-GtsGNodeClass * gts_gnode_class                (void);
-GtsGNode *      gts_gnode_new                  (GtsGNodeClass * klass);
-void            gts_gnode_foreach_neighbor     (GtsGNode * n, 
-						GtsGraph * g,
-						GtsFunc func,
-						gpointer data);
-void            gts_gnode_foreach_edge         (GtsGNode * n,
-						GtsGraph * g,
-						GtsFunc func,
-						gpointer data);
-guint           gts_gnode_degree               (GtsGNode * n,
-						GtsGraph * g);
-gfloat          gts_gnode_move_cost            (GtsGNode * n,
-						GtsGraph * src,
-						GtsGraph * dst);
-gfloat          gts_gnode_weight               (GtsGNode * n);
-
-GTS_C_VAR
-gboolean        gts_allow_floating_gnodes;
-
-/* GtsNGNode: graph.c */
-
-typedef struct _GtsNGNode         GtsNGNode;
-typedef struct _GtsNGNodeClass    GtsNGNodeClass;
-
-struct _GtsNGNode {
-  GtsGNode node;
-
-  guint id;
-};
-
-struct _GtsNGNodeClass {
-  GtsGNodeClass parent_class;
-};
-
-#define GTS_NGNODE(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsNGNode,\
-					           gts_ngnode_class ())
-#define GTS_NGNODE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsNGNodeClass,\
-						         gts_ngnode_class())
-#define GTS_IS_NGNODE(obj)         (gts_object_is_from_class (obj,\
-						   gts_ngnode_class ()))
-     
-GtsNGNodeClass * gts_ngnode_class                (void);
-GtsNGNode *      gts_ngnode_new                  (GtsNGNodeClass * klass,
-						  guint id);
-
-/* GtsWGNode: graph.c */
-
-typedef struct _GtsWGNode         GtsWGNode;
-typedef struct _GtsWGNodeClass    GtsWGNodeClass;
-
-struct _GtsWGNode {
-  GtsGNode node;
-  
-  gfloat weight;
-};
-
-struct _GtsWGNodeClass {
-  GtsGNodeClass parent_class;
-};
-
-#define GTS_WGNODE(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsWGNode,\
-					           gts_wgnode_class ())
-#define GTS_WGNODE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsWGNodeClass,\
-						         gts_wgnode_class())
-#define GTS_IS_WGNODE(obj)         (gts_object_is_from_class (obj,\
-						   gts_wgnode_class ()))
-     
-GtsWGNodeClass * gts_wgnode_class                (void);
-GtsWGNode *      gts_wgnode_new                  (GtsWGNodeClass * klass,
-						  gfloat weight);
-
-/* GtsPNode */
-
-typedef struct _GtsPNode         GtsPNode;
-typedef struct _GtsPNodeClass    GtsPNodeClass;
-
-struct _GtsPNode {
-  GtsGNode node;
-
-  gpointer data;
-};
-
-struct _GtsPNodeClass {
-  GtsGNodeClass parent_class;
-};
-
-#define GTS_PNODE(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsPNode,\
-					           gts_pnode_class ())
-#define GTS_PNODE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsPNodeClass,\
-						         gts_pnode_class())
-#define GTS_IS_PNODE(obj)         (gts_object_is_from_class (obj,\
-						   gts_pnode_class ()))
-     
-GtsPNodeClass * gts_pnode_class                (void);
-GtsPNode *      gts_pnode_new                  (GtsPNodeClass * klass,
-						gpointer data);
-
-/* GtsFNode */
-
-typedef struct _GtsFNode         GtsFNode;
-typedef struct _GtsFNodeClass    GtsFNodeClass;
-
-struct _GtsFNode {
-  GtsGNode node;
-
-  GtsFace * f;
-};
-
-struct _GtsFNodeClass {
-  GtsGNodeClass parent_class;
-};
-
-#define GTS_FNODE(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsFNode,\
-					           gts_fnode_class ())
-#define GTS_FNODE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsFNodeClass,\
-						         gts_fnode_class())
-#define GTS_IS_FNODE(obj)         (gts_object_is_from_class (obj,\
-						   gts_fnode_class ()))
-     
-GtsFNodeClass * gts_fnode_class                (void);
-GtsFNode *      gts_fnode_new                  (GtsFNodeClass * klass,
-						GtsFace * f);
-
-/* GtsGEdge: graph.c */
-
-typedef struct _GtsGEdge         GtsGEdge;
-typedef struct _GtsGEdgeClass    GtsGEdgeClass;
-
-struct _GtsGEdge {
-  GtsContainee containee;
-
-  GtsGNode * n1;
-  GtsGNode * n2;
-};
-
-struct _GtsGEdgeClass {
-  GtsContaineeClass parent_class;
-
-  GtsGEdge * (* link)   (GtsGEdge * e, GtsGNode * n1, GtsGNode * n2);
-  gfloat     (* weight) (GtsGEdge * e);
-  void       (* write)  (GtsGEdge * e, FILE * fp);
-};
-
-#define GTS_GEDGE(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsGEdge,\
-					           gts_gedge_class ())
-#define GTS_GEDGE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsGEdgeClass,\
-						         gts_gedge_class())
-#define GTS_IS_GEDGE(obj)         (gts_object_is_from_class (obj,\
-						   gts_gedge_class ()))
-     
-GtsGEdgeClass * gts_gedge_class                (void);
-GtsGEdge *      gts_gedge_new                  (GtsGEdgeClass * klass,
-						GtsGNode * n1,
-						GtsGNode * n2);
-gfloat          gts_gedge_weight               (GtsGEdge * e);
-#define         gts_gedge_connects(e, a1, a2)\
-   (((e)->n1 == a1 && (e)->n2 == a2) || ((e)->n1 == a2 && (e)->n2 == a1)) 
-
-/* GtsPGEdge: graph.c */
-
-typedef struct _GtsPGEdge         GtsPGEdge;
-typedef struct _GtsPGEdgeClass    GtsPGEdgeClass;
-
-struct _GtsPGEdge {
-  GtsGEdge gedge;
-
-  gpointer data;
-};
-
-struct _GtsPGEdgeClass {
-  GtsGEdgeClass parent_class;
-};
-
-#define GTS_PGEDGE(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsPGEdge,\
-					           gts_pgedge_class ())
-#define GTS_PGEDGE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsPGEdgeClass,\
-						         gts_pgedge_class())
-#define GTS_IS_PGEDGE(obj)         (gts_object_is_from_class (obj,\
-						   gts_pgedge_class ()))
-     
-GtsPGEdgeClass * gts_pgedge_class                (void);
-GtsPGEdge *      gts_pgedge_new                  (GtsPGEdgeClass * klass,
-						  GtsGNode * n1,
-						  GtsGNode * n2,
-						  gpointer data);
-
-/* GtsWGEdge: graph.c */
-
-typedef struct _GtsWGEdge         GtsWGEdge;
-typedef struct _GtsWGEdgeClass    GtsWGEdgeClass;
-
-struct _GtsWGEdge {
-  GtsGEdge gedge;
-
-  gfloat weight;
-};
-
-struct _GtsWGEdgeClass {
-  GtsGEdgeClass parent_class;
-};
-
-#define GTS_WGEDGE(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsWGEdge,\
-					           gts_wgedge_class ())
-#define GTS_WGEDGE_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsWGEdgeClass,\
-						         gts_wgedge_class())
-#define GTS_IS_WGEDGE(obj)         (gts_object_is_from_class (obj,\
-						   gts_wgedge_class ()))
-     
-GtsWGEdgeClass * gts_wgedge_class                (void);
-GtsWGEdge *      gts_wgedge_new                  (GtsWGEdgeClass * klass,
-						  GtsGNode * n1,
-						  GtsGNode * n2,
-						  gfloat weight);
-
-/* GtsGraph: graph.c */
-
-struct _GtsGraph {
-  GtsHashContainer object;
-
-  GtsGraphClass * graph_class;
-  GtsGNodeClass * node_class;
-  GtsGEdgeClass * edge_class;
-};
-
-struct _GtsGraphClass {
-  GtsHashContainerClass parent_class;
-
-  gfloat (* weight) (GtsGraph *);
-};
-
-#define GTS_GRAPH(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsGraph,\
-					           gts_graph_class ())
-#define GTS_GRAPH_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsGraphClass,\
-						         gts_graph_class())
-#define GTS_IS_GRAPH(obj)         (gts_object_is_from_class (obj,\
-						   gts_graph_class ()))
-     
-GtsGraphClass * gts_graph_class                  (void);
-GtsGraph *      gts_graph_new                    (GtsGraphClass * klass,
-						  GtsGNodeClass * node_class,
-						  GtsGEdgeClass * edge_class);
-void            gts_graph_print_stats            (GtsGraph * g,
-						  FILE * fp);
-typedef struct _GtsGraphTraverse GtsGraphTraverse;
-typedef enum   { GTS_BREADTH_FIRST
-               }   GtsTraverseType;
-GtsGraphTraverse * gts_graph_traverse_new        (GtsGraph * g, 
-						  GtsGNode * n,
-						  GtsTraverseType type,
-						  gboolean reinit);
-GtsGNode *         gts_graph_traverse_next       (GtsGraphTraverse * t);
-GtsGNode *         gts_graph_traverse_what_next  (GtsGraphTraverse * t);
-void               gts_graph_traverse_destroy    (GtsGraphTraverse * t);
-void               gts_graph_foreach_edge        (GtsGraph * g,
-						  GtsFunc func,
-						  gpointer data);
-gfloat             gts_graph_weight              (GtsGraph * g);
-guint              gts_graph_distance_sum        (GtsGraph * g, 
-						  GtsGNode * center);
-GtsGNode *         gts_graph_farthest            (GtsGraph * g, 
-						  GSList * gnodes);
-guint              gts_graph_edges_cut           (GtsGraph * g);
-gfloat             gts_graph_edges_cut_weight    (GtsGraph * g);
-void               gts_graph_write               (GtsGraph * g, 
-						  FILE * fp);
-void               gts_graph_write_dot           (GtsGraph * g, 
-						  FILE * fp);
-GtsGraph *         gts_graph_read                (GtsFile * fp);
-guint              gts_graph_read_jostle         (GtsGraph * g, 
-						  GtsFile * fp);
-
-/* GtsWGraph: graph.c */
-
-typedef struct _GtsWGraph      GtsWGraph;
-typedef struct _GtsWGraphClass GtsWGraphClass;
-
-struct _GtsWGraph {
-  GtsGraph graph;
-
-  gfloat weight;
-};
-
-struct _GtsWGraphClass {
-  GtsGraphClass parent_class;
-};
-
-#define GTS_WGRAPH(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsWGraph,\
-					           gts_wgraph_class ())
-#define GTS_WGRAPH_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsWGraphClass,\
-						         gts_wgraph_class())
-#define GTS_IS_WGRAPH(obj)         (gts_object_is_from_class (obj,\
-						   gts_wgraph_class ()))
-     
-GtsWGraphClass * gts_wgraph_class                (void);
-gfloat           gts_wgraph_weight_max           (GtsWGraph * wg);
-
-/* Surface graph: graph.c */
-
-GtsGraph *       gts_surface_graph_new           (GtsGraphClass * klass,
-						  GtsSurface * s);
-GtsSurface *     gts_surface_graph_surface       (GtsGraph * surface_graph,
-						  GtsSurface * s);
-
-/* Segments graph: graph.c */
-
-GtsGraph *       gts_segments_graph_new          (GtsGraphClass * klass,
-						  GSList * segments);
-
-/* GtsGNodeSplit: pgraph.c */
-
-typedef struct _GtsGNodeSplit         GtsGNodeSplit;
-typedef struct _GtsGNodeSplitClass    GtsGNodeSplitClass;
-
-struct _GtsGNodeSplit {
-  GtsObject object;
-
-  GtsGNode * n;
-  GtsObject * n1;
-  GtsObject * n2;
-};
-
-struct _GtsGNodeSplitClass {
-  GtsObjectClass parent_class;
-};
-
-#define GTS_GNODE_SPLIT(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsGNodeSplit,\
-					           gts_gnode_split_class ())
-#define GTS_GNODE_SPLIT_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsGNodeSplitClass,\
-						         gts_gnode_split_class())
-#define GTS_IS_GNODE_SPLIT(obj)         (gts_object_is_from_class (obj,\
-						   gts_gnode_split_class ()))
-#define GTS_GNODE_SPLIT_N1(ns) (GTS_IS_GNODE_SPLIT ((ns)->n1) ? GTS_GNODE_SPLIT ((ns)->n1)->n : GTS_GNODE ((ns)->n1))
-#define GTS_GNODE_SPLIT_N2(ns) (GTS_IS_GNODE_SPLIT ((ns)->n2) ? GTS_GNODE_SPLIT ((ns)->n2)->n : GTS_GNODE ((ns)->n2))
-     
-GtsGNodeSplitClass * gts_gnode_split_class    (void);
-GtsGNodeSplit *      gts_gnode_split_new      (GtsGNodeSplitClass * klass,
-					       GtsGNode * n,
-					       GtsObject * n1,
-					       GtsObject * n2);
-void                 gts_gnode_split_collapse (GtsGNodeSplit * ns,
-					       GtsGraph * g,
-					       GtsWGEdgeClass * klass);
-void                 gts_gnode_split_expand   (GtsGNodeSplit * ns,
-					       GtsGraph * g);
-
-/* GtsPGraph: pgraph.c */
-
-typedef struct _GtsPGraph         GtsPGraph;
-typedef struct _GtsPGraphClass    GtsPGraphClass;
-
-struct _GtsPGraph {
-  GtsObject object;
-
-  GtsGraph * g;
-  GPtrArray * split;
-  GArray * levels;
-  GtsGNodeSplitClass * split_class;
-  GtsWGEdgeClass * edge_class;
-  guint pos, min, level;
-};
-
-struct _GtsPGraphClass {
-  GtsObjectClass parent_class;
-};
-
-#define GTS_PGRAPH(obj)            GTS_OBJECT_CAST (obj,\
-					           GtsPGraph,\
-					           gts_pgraph_class ())
-#define GTS_PGRAPH_CLASS(klass)    GTS_OBJECT_CLASS_CAST (klass,\
-						         GtsPGraphClass,\
-						         gts_pgraph_class())
-#define GTS_IS_PGRAPH(obj)         (gts_object_is_from_class (obj,\
-						   gts_pgraph_class ()))
-     
-GtsPGraphClass * gts_pgraph_class            (void);
-GtsPGraph *      gts_pgraph_new              (GtsPGraphClass * klass,
-					      GtsGraph * g,
-					      GtsGNodeSplitClass * split_class,
-					      GtsWGNodeClass * node_class,
-					      GtsWGEdgeClass * edge_class,
-					      guint min);
-GtsGNodeSplit *  gts_pgraph_add_node         (GtsPGraph * pg);
-GtsGNodeSplit *  gts_pgraph_remove_node      (GtsPGraph * pg);
-void             gts_pgraph_set_node_number  (GtsPGraph *pg,
-					      guint n);
-guint            gts_pgraph_get_node_number  (GtsPGraph *pg);
-guint            gts_pgraph_min_node_number  (GtsPGraph *pg);
-guint            gts_pgraph_max_node_number  (GtsPGraph *pg);
-void             gts_pgraph_foreach_node     (GtsPGraph *pg,
-					      GtsFunc func,
-					      gpointer data);
-gboolean         gts_pgraph_down             (GtsPGraph * pg,
-					      GtsFunc func,
-					      gpointer data);
-/* Graph partition: partition.c */
-
-GSList *         gts_graph_bubble_partition           (GtsGraph * g, 
-						       guint np, 
-						       guint niter,
-						       GtsFunc step_info,
-						       gpointer data);
-guint            gts_graph_partition_edges_cut        (GSList * partition);
-gfloat           gts_graph_partition_edges_cut_weight (GSList * partition);
-void             gts_graph_partition_print_stats      (GSList * partition,
-						       FILE * fp);
-gfloat           gts_graph_partition_balance          (GSList * partition);
-GSList *         gts_graph_partition_clone            (GSList * partition);
-GSList *         gts_graph_recursive_bisection        (GtsWGraph * wg,
-						       guint n,
-						       guint ntry,
-						       guint mmax,
-						       guint nmin,
-						       gfloat imbalance);
-void             gts_graph_partition_destroy          (GSList * partition);
-
-/* Graph bisection: partition.c */
-
-typedef struct _GtsGraphBisection GtsGraphBisection;
-
-struct _GtsGraphBisection {
-  GtsGraph * g;
-  GtsGraph * g1;
-  GtsGraph * g2;
-  GHashTable * bg1;
-  GHashTable * bg2;
-};
-
-gboolean            gts_graph_bisection_check      (GtsGraphBisection * bg);
-GtsGraphBisection * gts_graph_ggg_bisection        (GtsGraph * g, 
-						    guint ntry);
-GtsGraphBisection * gts_graph_bfgg_bisection       (GtsGraph * g, 
-						    guint ntry);
-gdouble             gts_graph_bisection_kl_refine  (GtsGraphBisection * bg,
-						    guint mmax);
-gdouble             gts_graph_bisection_bkl_refine (GtsGraphBisection * bg,
-						    guint mmax,
-						    gfloat imbalance);
-GtsGraphBisection * gts_graph_bisection_new        (GtsWGraph * wg,
-						    guint ntry,
-						    guint mmax,
-						    guint nmin,
-						    gfloat imbalance);
-void                gts_graph_bisection_destroy    (GtsGraphBisection * bg,
-						    gboolean destroy_graphs);
-
-#ifdef __cplusplus
-}
-#endif /* __cplusplus */
-
-#endif /* __GTS_H__ */
diff --git a/src/gts/heap.c b/src/gts/heap.c
deleted file mode 100644
index 4a37e58..0000000
--- a/src/gts/heap.c
+++ /dev/null
@@ -1,258 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <stdlib.h>
-#include "gts.h"
-
-#define PARENT(i) ((i) >= 2 ? (i)/2 : 0)
-#define LEFT_CHILD(i) (2*(i))
-#define RIGHT_CHILD(i) (2*(i) + 1)
-
-struct _GtsHeap {
-  GPtrArray * elts;
-  GCompareFunc func;
-  gboolean frozen;
-};
-
-/**
- * gts_heap_new:
- * @compare_func: a GCompareFunc.
- *
- * Returns: a new #GtsHeap using @compare_func as a sorting function.
- */
-GtsHeap * gts_heap_new (GCompareFunc compare_func)
-{
-  GtsHeap * heap;
-
-  g_return_val_if_fail (compare_func != NULL, NULL);
-  
-  heap = g_malloc (sizeof(GtsHeap));
-  heap->elts = g_ptr_array_new ();
-  heap->func = compare_func;
-  heap->frozen = FALSE;
-  return heap;
-}
-
-static void sift_up (GtsHeap * heap, guint i)
-{
-  gpointer parent, child;
-  guint p;
-  gpointer * pdata = heap->elts->pdata;
-  GCompareFunc func = heap->func;
-
-  child = pdata[i - 1];
-  while ((p = PARENT (i))) {
-    parent = pdata[p - 1];
-    if ((*func) (parent, child) > 0) {
-      pdata[p - 1] = child;
-      pdata[i - 1] = parent;
-      i = p;
-    }
-    else
-      i = 0;
-  }
-}
-
-/**
- * gts_heap_insert:
- * @heap: a #GtsHeap.
- * @p: a pointer to add to the heap.
- *
- * Inserts a new element @p in the heap.
- */
-void gts_heap_insert (GtsHeap * heap, gpointer p)
-{
-  g_return_if_fail (heap != NULL);
-
-  g_ptr_array_add (heap->elts, p);
-  if (!heap->frozen)
-    sift_up (heap, heap->elts->len);
-}
-
-static void sift_down (GtsHeap * heap, guint i)
-{
-  gpointer left_child, right_child, child, parent;
-  guint lc, rc, c;
-  gpointer * pdata = heap->elts->pdata;
-  guint len = heap->elts->len;
-  GCompareFunc func = heap->func;
-
-  lc = LEFT_CHILD (i);
-  rc = RIGHT_CHILD (i);
-  left_child = lc <= len ? pdata[lc - 1] : NULL;
-  right_child = rc <= len ? pdata[rc - 1] : NULL;
-
-  parent = pdata[i - 1];
-  while (left_child != NULL) {
-    if (right_child == NULL ||
-	(*func) (left_child, right_child) < 0) {
-      child = left_child;
-      c = lc;
-    }
-    else {
-      child = right_child;
-      c = rc;
-    }
-    if ((*func) (parent, child) > 0) {
-      pdata[i - 1] = child;
-      pdata[c - 1] = parent;
-      i = c;
-      lc = LEFT_CHILD (i);
-      rc = RIGHT_CHILD (i);
-      left_child = lc <= len ? pdata[lc - 1] : NULL;
-      right_child = rc <= len ? pdata[rc - 1] : NULL;      
-    }
-    else
-      left_child = NULL;
-  }
-}
-
-/**
- * gts_heap_remove_top:
- * @heap: a #GtsHeap.
- *
- * Removes the element at the top of the heap.
- *
- * Returns: the element at the top of the heap.
- */
-gpointer gts_heap_remove_top (GtsHeap * heap)
-{
-  gpointer root;
-  GPtrArray * elts;
-  guint len;
-
-  g_return_val_if_fail (heap != NULL, NULL);
-
-  elts = heap->elts; len = elts->len;
-
-  if (len == 0)
-    return NULL;
-  if (len == 1)
-    return g_ptr_array_remove_index (elts, 0);
-
-  root = elts->pdata[0];
-  elts->pdata[0] = g_ptr_array_remove_index (elts, len - 1);
-  sift_down (heap, 1);
-  return root;
-}
-
-/**
- * gts_heap_top:
- * @heap: a #GtsHeap.
- *
- * Returns: the element at the top of the heap.
- */
-gpointer gts_heap_top (GtsHeap * heap)
-{
-  GPtrArray * elts;
-  guint len;
-
-  g_return_val_if_fail (heap != NULL, NULL);
-
-  elts = heap->elts; 
-  len = elts->len;
-  if (len == 0)
-    return NULL;
-  return elts->pdata[0];
-}
-
-/**
- * gts_heap_destroy:
- * @heap: a #GtsHeap.
- * 
- * Free all the memory allocated for @heap.
- */
-void gts_heap_destroy (GtsHeap * heap)
-{
-  g_return_if_fail (heap != NULL);
-
-  g_ptr_array_free (heap->elts, TRUE);
-  g_free (heap);
-}
-
-/**
- * gts_heap_thaw:
- * @heap: a #GtsHeap.
- *
- * If @heap has been frozen previously using gts_heap_freeze(), reorder it
- * in O(n) time and unfreeze it.
- */
-void gts_heap_thaw (GtsHeap * heap)
-{
-  guint i;
-  
-  g_return_if_fail (heap != NULL);
-
-  if (!heap->frozen)
-    return;
-
-  for (i = heap->elts->len/2; i > 0; i--)
-    sift_down (heap, i);
-
-  heap->frozen = FALSE;
-}
-
-/**
- * gts_heap_foreach:
- * @heap: a #GtsHeap.
- * @func: the function to call for each element in the heap.
- * @user_data: to pass to @func.
- */
-void gts_heap_foreach (GtsHeap * heap, 
-		       GFunc func,
-		       gpointer user_data)
-{
-  guint i;
-  GPtrArray * elts;
-  
-  g_return_if_fail (heap != NULL);
-  g_return_if_fail (func != NULL);
-
-  elts = heap->elts;
-  for (i = 0; i < elts->len; i++)
-    (*func) (elts->pdata[i], user_data);
-}
-
-/**
- * gts_heap_freeze:
- * @heap: a #GtsHeap.
- *
- * Freezes the heap. Any subsequent operation will not preserve the heap
- * property. Used in conjunction with gts_heap_insert() and gts_heap_thaw()
- * to create a heap in O(n) time.
- */
-void gts_heap_freeze (GtsHeap * heap)
-{
-  g_return_if_fail (heap != NULL);
-
-  heap->frozen = TRUE;
-}
-
-/**
- * gts_heap_size:
- * @heap: a #GtsHeap.
- *
- * Returns: the number of items in @heap.
- */
-guint gts_heap_size (GtsHeap * heap)
-{
-  g_return_val_if_fail (heap != NULL, 0);
-
-  return heap->elts->len;
-}
diff --git a/src/gts/hsurface.c b/src/gts/hsurface.c
deleted file mode 100644
index 80ac66a..0000000
--- a/src/gts/hsurface.c
+++ /dev/null
@@ -1,405 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <stdlib.h>
-#include <string.h>
-#include "gts.h"
-
-#define HEAP_INSERT_HSPLIT(h, e) ((e)->index = gts_eheap_insert (h, e))
-#define HEAP_REMOVE_HSPLIT(h, e) (gts_eheap_remove (h, (e)->index),\
-				  (e)->index = NULL)
-
-static void hsplit_init (GtsHSplit * hsplit)
-{
-  hsplit->index = NULL;
-  hsplit->parent = NULL;
-  hsplit->nchild = 0;
-}
-
-/**
- * gts_hsplit_class:
- *
- * Returns: the #GtsHSplitClass.
- */
-GtsHSplitClass * gts_hsplit_class (void)
-{
-  static GtsHSplitClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo hsplit_info = {
-      "GtsHSplit",
-      sizeof (GtsHSplit),
-      sizeof (GtsHSplitClass),
-      (GtsObjectClassInitFunc) NULL,
-      (GtsObjectInitFunc) hsplit_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_split_class ()), 
-				  &hsplit_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_hsplit_new:
- * @klass: a #GtsHSplitClass.
- * @vs: a #GtsSplit.
- *
- * Returns: a new #GtsHSplit, hierarchical extension of @vs.
- */
-GtsHSplit * gts_hsplit_new (GtsHSplitClass * klass, GtsSplit * vs)
-{
-  GtsHSplit * hs;
-
-  g_return_val_if_fail (vs != NULL, NULL);
-
-  hs = GTS_HSPLIT (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  memcpy (hs, vs, sizeof (GtsSplit));
-  GTS_OBJECT (hs)->reserved = NULL;
-
-  return hs;
-}
-
-/**
- * gts_hsplit_collapse:
- * @hs: a #GtsHSplit.
- * @hsurface: a #GtsHSurface.
- *
- * Collapses the #GtsSplit defined by @hs, updates the expandable and
- * collapsable priority heaps of @hsurface.  
- */
-void gts_hsplit_collapse (GtsHSplit * hs,
-			  GtsHSurface * hsurface)
-{
-  GtsHSplit * parent;
-  GtsSplit * vs;
-
-  g_return_if_fail (hs != NULL);
-  g_return_if_fail (hs->nchild == 2);
-  g_return_if_fail (hsurface != NULL);
-
-  gts_split_collapse (GTS_SPLIT (hs), hsurface->s->edge_class, NULL);
-
-  hsurface->nvertex--;
-  hs->nchild = 0;
-  HEAP_REMOVE_HSPLIT (hsurface->collapsable, hs);
-  HEAP_INSERT_HSPLIT (hsurface->expandable, hs);
-
-  vs = GTS_SPLIT (hs);
-  if (GTS_IS_HSPLIT (vs->v1))
-    HEAP_REMOVE_HSPLIT (hsurface->expandable, GTS_HSPLIT (vs->v1));
-  if (GTS_IS_HSPLIT (vs->v2))
-    HEAP_REMOVE_HSPLIT (hsurface->expandable, GTS_HSPLIT (vs->v2));
-
-  parent = hs->parent;
-  if (parent && ++parent->nchild == 2)
-    HEAP_INSERT_HSPLIT (hsurface->collapsable, parent);
-}
-
-/**
- * gts_hsplit_expand:
- * @hs: a #GtsHSplit.
- * @hsurface: a #GtsHSurface.
- *
- * Expands the #GtsSplit defined by @hs (which must be expandable)
- * and updates the priority heaps of @hsurface.
- */
-void gts_hsplit_expand (GtsHSplit * hs,
-			GtsHSurface * hsurface)
-{
-  GtsHSplit * parent;
-  GtsSplit * vs;
-
-  g_return_if_fail (hs != NULL);
-  g_return_if_fail (hsurface != NULL);
-  g_return_if_fail (hs->nchild == 0);
-
-  gts_split_expand (GTS_SPLIT (hs), hsurface->s, hsurface->s->edge_class);
-  hsurface->nvertex++;
-  hs->nchild = 2;
-  HEAP_REMOVE_HSPLIT (hsurface->expandable, hs);
-  HEAP_INSERT_HSPLIT (hsurface->collapsable, hs);
-
-  vs = GTS_SPLIT (hs);
-  if (GTS_IS_HSPLIT (vs->v1))
-    HEAP_INSERT_HSPLIT (hsurface->expandable, GTS_HSPLIT (vs->v1));
-  if (GTS_IS_HSPLIT (vs->v2))
-    HEAP_INSERT_HSPLIT (hsurface->expandable, GTS_HSPLIT (vs->v2));
-
-  parent = hs->parent;
-  if (parent && parent->nchild-- == 2)
-    HEAP_REMOVE_HSPLIT (hsurface->collapsable, parent);
-}
-
-static void hsurface_destroy (GtsObject * object)
-{
-  GtsHSurface * hs = GTS_HSURFACE (object);
-
-  gts_hsurface_traverse (hs, G_POST_ORDER, -1,
-			 (GtsSplitTraverseFunc) gts_object_destroy, 
-			 NULL);
-  g_slist_free (hs->roots);
-  if (hs->expandable)
-    gts_eheap_destroy (hs->expandable);
-  if (hs->collapsable)
-    gts_eheap_destroy (hs->collapsable);
-  g_ptr_array_free (hs->split, TRUE);
-
-  (* GTS_OBJECT_CLASS (gts_hsurface_class ())->parent_class->destroy) (object);
-}
-
-static void hsurface_class_init (GtsObjectClass * klass)
-{
-  klass->destroy = hsurface_destroy;
-}
-
-static void hsurface_init (GtsHSurface * hsurface)
-{
-  hsurface->s = NULL;
-  hsurface->roots = NULL;
-  hsurface->expandable = hsurface->collapsable = NULL;
-  hsurface->split = g_ptr_array_new ();
-  hsurface->nvertex = 0;
-}
-
-/**
- * gts_hsurface_class:
- *
- * Returns: the #GtsHSurfaceClass.
- */
-GtsHSurfaceClass * gts_hsurface_class (void)
-{
-  static GtsHSurfaceClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo hsurface_info = {
-      "GtsHSurface",
-      sizeof (GtsHSurface),
-      sizeof (GtsHSurfaceClass),
-      (GtsObjectClassInitFunc) hsurface_class_init,
-      (GtsObjectInitFunc) hsurface_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (gts_object_class (), 
-				  &hsurface_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_hsurface_new:
- * @klass: a #GtsHSurfaceClass.
- * @hsplit_class: a #GtsHSplitClass.
- * @psurface: a #GtsPSurface.
- * @expand_key: a #GtsKeyFunc used to order the priority heap of expandable 
- * #GtsHSplit.
- * @expand_data: data to be passed to @expand_key.
- * @collapse_key: a #GtsKeyFunc used to order the priority heap of collapsable
- * #GtsHSplit.
- * @collapse_data: data to be passed to @collapsed_key.
- *
- * Returns: a new #GtsHSurface, hierarchical extension of @psurface
- * and using #GtsHSplit of class @hsplit_class. Note that @psurface is
- * destroyed in the process.
- */
-GtsHSurface * gts_hsurface_new (GtsHSurfaceClass * klass,
-				GtsHSplitClass * hsplit_class,
-				GtsPSurface * psurface,
-				GtsKeyFunc expand_key,
-				gpointer expand_data,
-				GtsKeyFunc collapse_key,
-				gpointer collapse_data)
-{
-  GtsHSurface * hsurface;
-
-  g_return_val_if_fail (klass != NULL, NULL);
-  g_return_val_if_fail (hsplit_class != NULL, NULL);
-  g_return_val_if_fail (psurface != NULL, NULL);
-  g_return_val_if_fail (expand_key != NULL, NULL);
-  g_return_val_if_fail (collapse_key != NULL, NULL);
-
-  hsurface = GTS_HSURFACE (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  hsurface->s = psurface->s;
-  hsurface->expandable = gts_eheap_new (expand_key, expand_data);
-  hsurface->collapsable = gts_eheap_new (collapse_key, collapse_data);
-  g_ptr_array_set_size (hsurface->split, psurface->split->len);
-
-  while (gts_psurface_remove_vertex (psurface))
-    ;
-  while (psurface->pos) {
-    GtsSplit * vs = g_ptr_array_index (psurface->split, psurface->pos - 1);
-    GtsHSplit * hs = gts_hsplit_new (hsplit_class, vs);
-
-    g_ptr_array_index (hsurface->split, psurface->pos - 1) = hs;
-    psurface->pos--;
-
-    hs->parent = GTS_OBJECT (vs)->reserved;
-    if (hs->parent) {
-      GtsSplit * vsp = GTS_SPLIT (hs->parent);
-
-      if (vsp->v1 == GTS_OBJECT (vs)) {
-	g_assert (vsp->v2 != GTS_OBJECT (vs));
-	vsp->v1 = GTS_OBJECT (hs);
-      }
-      else {
-	g_assert (vsp->v2 == GTS_OBJECT (vs));
-	vsp->v2 = GTS_OBJECT (hs);
-      }
-    }
-    else
-      hsurface->roots = g_slist_prepend (hsurface->roots, hs);
-
-    hs->nchild = 0;
-    if (GTS_IS_SPLIT (vs->v1))
-      GTS_OBJECT (vs->v1)->reserved = hs;
-    else
-      hs->nchild++;
-    if (GTS_IS_SPLIT (vs->v2))
-      GTS_OBJECT (vs->v2)->reserved = hs;
-    else
-      hs->nchild++;
-    
-    gts_split_expand (vs, psurface->s, psurface->s->edge_class);
-
-    if (hs->nchild == 2)
-      HEAP_INSERT_HSPLIT (hsurface->collapsable, hs);
-  }
-
-  hsurface->nvertex = gts_surface_vertex_number (hsurface->s);
-  gts_object_destroy (GTS_OBJECT (psurface));
-
-  return hsurface;
-}
-
-/**
- * gts_hsurface_traverse:
- * @hsurface: a #GtsHSurface.
- * @order: the order in which nodes are visited - G_PRE_ORDER or G_POST_ORDER.
- * @depth: the maximum depth of the traversal. Nodes below this depth
- * will not be visited. If max_depth is -1 all nodes in the tree are
- * visited. If depth is 1, only the root is visited. If depth is 2,
- * the root and its children are visited. And so on.
- * @func: the function to call for each visited #GtsHSplit.
- * @data: user data to pass to the function.
- *
- * Traverses a hierarchical surface starting from its roots. It calls
- * the given function for each #GtsHSplit visited. 
- * See also gts_split_traverse().
- */
-void gts_hsurface_traverse (GtsHSurface *    hsurface,
-			    GTraverseType    order,
-			    gint             depth,
-			    GtsSplitTraverseFunc func,
-			    gpointer         data)
-{
-  GSList * i;
-
-  g_return_if_fail (hsurface != NULL);
-  g_return_if_fail (func != NULL);
-  g_return_if_fail (order < G_LEVEL_ORDER);
-  g_return_if_fail (depth == -1 || depth > 0);
-
-  i = hsurface->roots;
-  while (i) {
-    gts_split_traverse (i->data, order, depth, func, data);
-    i = i->next;
-  }
-}
-
-/**
- * gts_hsurface_foreach:
- * @hsurface: a #GtsHSurface.
- * @order: the order in which #GtsHSplit are visited - G_PRE_ORDER or 
- * G_POST_ORDER.
- * @func: the function to call for each visited #GtsHSplit.
- * @data: user data to pass to the function.
- *
- * Starts by expanding all the #GtsHSplit of @hsurface. If @order is
- * G_PRE_ORDER, calls @func for each #GtsHSplit and collapses it. If
- * order is G_POST_ORDER, collapses each #GtsHSplit first and then
- * calls @func. The traversal can be halted at any point by returning
- * TRUE from func.  
- */
-void gts_hsurface_foreach (GtsHSurface * hsurface,
-			   GTraverseType order,
-			   GtsFunc       func,
-			   gpointer      data)
-{
-  GtsHSplit * hs;
-  guint i = 0, len;
-  gboolean stop = FALSE;
-
-  g_return_if_fail (hsurface != NULL);
-  g_return_if_fail (func != NULL);
-  g_return_if_fail (order == G_PRE_ORDER || order == G_POST_ORDER);
-
-  while ((hs = gts_eheap_top (hsurface->expandable, NULL))) 
-    gts_hsplit_expand (hs, hsurface);
-
-  len = hsurface->split->len;
-  switch (order) {
-  case G_PRE_ORDER:
-    while (i < len && !stop) {
-      GtsHSplit * hs = g_ptr_array_index (hsurface->split, i);
-      stop = (*func) (hs, data);
-      if (!stop)
-	gts_hsplit_collapse (hs, hsurface);
-      i++;
-    }
-    break;
-  case G_POST_ORDER:
-    while (i < len && !stop) {
-      GtsHSplit * hs = g_ptr_array_index (hsurface->split, i);
-      gts_hsplit_collapse (hs, hsurface);
-      stop = (*func) (hs, data);
-      i++;
-    }
-    break;
-  default:
-    g_assert_not_reached ();
-  }
-}
-
-/**
- * gts_hsurface_height:
- * @hsurface: a #GtsHSurface.
- *
- * Returns: the maximum height of the tree described by @hsurface.
- */
-guint gts_hsurface_height (GtsHSurface * hsurface)
-{
-  GSList * i;
-  guint height = 0;
-
-  g_return_val_if_fail (hsurface != NULL, 0);
-
-  i = hsurface->roots;
-  while (i) {
-    guint tmp_height = gts_split_height (i->data);
-    if (tmp_height > height)
-      height = tmp_height;
-    i = i->next;
-  }
-
-  return height;
-}
diff --git a/src/gts/iso.c b/src/gts/iso.c
deleted file mode 100644
index 5995a19..0000000
--- a/src/gts/iso.c
+++ /dev/null
@@ -1,455 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include "gts.h"
-
-typedef enum { LEFT = 0, RIGHT = 1 } Orientation;
-
-typedef struct {
-  GtsVertex * v;
-  Orientation orientation;
-} OrientedVertex;
-
-struct _GtsIsoSlice {
-  OrientedVertex *** vertices;
-  guint nx, ny;
-};
-
-/* coordinates of the edges of the cube (see doc/isocube.fig) */
-static guint c[12][4] = {
-  {0, 0, 0, 0}, {0, 0, 0, 1}, {0, 0, 1, 1}, {0, 0, 1, 0},
-  {1, 0, 0, 0}, {1, 0, 0, 1}, {1, 1, 0, 1}, {1, 1, 0, 0},
-  {2, 0, 0, 0}, {2, 1, 0, 0}, {2, 1, 1, 0}, {2, 0, 1, 0}};
-
-/* first index is the edge number, second index is the edge orientation 
-   (RIGHT or LEFT), third index are the edges which this edge may connect to
-   in order */
-static guint edge[12][2][3] = {
-  {{9, 1, 8}, {4, 3, 7}},   /* 0 */
-  {{6, 2, 5}, {8, 0, 9}},   /* 1 */
-  {{10, 3, 11}, {5, 1, 6}}, /* 2 */
-  {{7, 0, 4}, {11, 2, 10}}, /* 3 */
-  {{3, 7, 0}, {8, 5, 11}},  /* 4 */
-  {{11, 4, 8}, {1, 6, 2}},  /* 5 */
-  {{2, 5, 1}, {9, 7, 10}},  /* 6 */
-  {{10, 6, 9}, {0, 4, 3}},  /* 7 */
-  {{5, 11, 4}, {0, 9, 1}},  /* 8 */
-  {{1, 8, 0}, {7, 10, 6}},  /* 9 */
-  {{6, 9, 7}, {3, 11, 2}},  /* 10 */
-  {{2, 10, 3}, {4, 8, 5}}   /* 11 */
-};
-
-static void ** malloc2D (guint nx, guint ny, gulong size)
-{
-  void ** m = g_malloc (nx*sizeof (void *));
-  guint i;
-
-  for (i = 0; i < nx; i++)
-    m[i] = g_malloc0 (ny*size);
-
-  return m;
-}
-
-static void free2D (void ** m, guint nx)
-{
-  guint i;
-
-  g_return_if_fail (m != NULL);
-
-  for (i = 0; i < nx; i++)
-    g_free (m[i]);
-  g_free (m);
-}
-
-/**
- * gts_grid_plane_new:
- * @nx:
- * @ny:
- *
- * Returns:
- */
-GtsGridPlane * gts_grid_plane_new (guint nx, guint ny)
-{
-  GtsGridPlane * g = g_malloc (sizeof (GtsGridPlane));
-
-  g->p = (GtsPoint **) malloc2D (nx, ny, sizeof (GtsPoint));
-  g->nx = nx;
-  g->ny = ny;
-  
-  return g;
-}
-
-/**
- * gts_grid_plane_destroy:
- * @g:
- *
- */
-void gts_grid_plane_destroy (GtsGridPlane * g)
-{
-  g_return_if_fail (g != NULL);
-
-  free2D ((void **) g->p, g->nx);
-  g_free (g);
-}
-
-/**
- * gts_iso_slice_new:
- * @nx: number of vertices in the x direction.
- * @ny: number of vertices in the y direction.
- *
- * Returns: a new #GtsIsoSlice.
- */
-GtsIsoSlice * gts_iso_slice_new (guint nx, guint ny)
-{
-  GtsIsoSlice * slice;
-
-  g_return_val_if_fail (nx > 1, NULL);
-  g_return_val_if_fail (ny > 1, NULL);
-
-  slice = g_malloc (sizeof (GtsIsoSlice));
-
-  slice->vertices = g_malloc (3*sizeof (OrientedVertex **));
-  slice->vertices[0] = 
-    (OrientedVertex **) malloc2D (nx, ny, sizeof (OrientedVertex));
-  slice->vertices[1] = 
-    (OrientedVertex **) malloc2D (nx - 1, ny, sizeof (OrientedVertex));
-  slice->vertices[2] = 
-    (OrientedVertex **) malloc2D (nx, ny - 1, sizeof (OrientedVertex));
-  slice->nx = nx;
-  slice->ny = ny;
-
-  return slice;
-}
-
-/**
- * gts_iso_slice_fill:
- * @slice: a #GtsIsoSlice.
- * @plane1: a #GtsGridPlane.
- * @plane2: another #GtsGridPlane.
- * @f1: values of the function corresponding to @plane1.
- * @f2: values of the function corresponding to @plane2.
- * @iso: isosurface value.
- * @klass: a #GtsVertexClass or one of its descendant to be used for the 
- * new vertices.
- *
- * Fill @slice with the coordinates of the vertices defined by 
- * f1 (x,y,z) = @iso and f2 (x, y, z) = @iso.
- */
-void gts_iso_slice_fill (GtsIsoSlice * slice,
-			 GtsGridPlane * plane1,
-			 GtsGridPlane * plane2,
-			 gdouble ** f1,
-			 gdouble ** f2,
-			 gdouble iso,
-			 GtsVertexClass * klass)
-{
-  OrientedVertex *** vertices;
-  GtsPoint ** p1, ** p2 = NULL;
-  guint i, j, nx, ny;
-
-  g_return_if_fail (slice != NULL);
-  g_return_if_fail (plane1 != NULL);
-  g_return_if_fail (f1 != NULL);
-  g_return_if_fail (f2 == NULL || plane2 != NULL);
-
-  p1 = plane1->p;
-  if (plane2) 
-    p2 = plane2->p;
-  vertices = slice->vertices;
-  nx = slice->nx;
-  ny = slice->ny;
-
-  if (f2)
-    for (i = 0; i < nx; i++)
-      for (j = 0; j < ny; j++) {
-	gdouble v1 = f1[i][j] - iso;
-	gdouble v2 = f2[i][j] - iso;
-	if ((v1 >= 0. && v2 < 0.) || (v1 < 0. && v2 >= 0.)) {
-	  gdouble c2 = v1/(v1 - v2), c1 = 1. - c2;
-	  vertices[0][i][j].v = 
-	    gts_vertex_new (klass,
-			    c1*p1[i][j].x + c2*p2[i][j].x,
-			    c1*p1[i][j].y + c2*p2[i][j].y,
-			    c1*p1[i][j].z + c2*p2[i][j].z);
-	  vertices[0][i][j].orientation = v2 >= 0. ? RIGHT : LEFT;
-	}
-	else
-	  vertices[0][i][j].v = NULL;
-      }
-  for (i = 0; i < nx - 1; i++)
-    for (j = 0; j < ny; j++) {
-      gdouble v1 = f1[i][j] - iso;
-      gdouble v2 = f1[i+1][j] - iso;
-      if ((v1 >= 0. && v2 < 0.) || (v1 < 0. && v2 >= 0.)) {
-	gdouble c2 = v1/(v1 - v2), c1 = 1. - c2;
-	vertices[1][i][j].v = 
-	  gts_vertex_new (klass,
-			  c1*p1[i][j].x + c2*p1[i+1][j].x,
-			  c1*p1[i][j].y + c2*p1[i+1][j].y,
-			  c1*p1[i][j].z + c2*p1[i+1][j].z);
-	vertices[1][i][j].orientation = v2 >= 0. ? RIGHT : LEFT;
-      }
-      else
-	vertices[1][i][j].v = NULL;
-    }
-  for (i = 0; i < nx; i++)
-    for (j = 0; j < ny - 1; j++) {
-      gdouble v1 = f1[i][j] - iso;
-      gdouble v2 = f1[i][j+1] - iso;
-      if ((v1 >= 0. && v2 < 0.) || (v1 < 0. && v2 >= 0.)) {
-	gdouble c2 = v1/(v1 - v2), c1 = 1. - c2;
-	vertices[2][i][j].v = 
-	  gts_vertex_new (klass,
-			  c1*p1[i][j].x + c2*p1[i][j+1].x,
-			  c1*p1[i][j].y + c2*p1[i][j+1].y,
-			  c1*p1[i][j].z + c2*p1[i][j+1].z);
-	vertices[2][i][j].orientation = v2 >= 0. ? RIGHT : LEFT;
-      }
-      else
-	vertices[2][i][j].v = NULL;
-    }
-}
- 
-/**
- * gts_iso_slice_fill_cartesian:
- * @slice: a #GtsIsoSlice.
- * @g: a #GtsCartesianGrid.
- * @f1: values of the function for plane z = @g.z.
- * @f2: values of the function for plane z = @g.z + @g.dz.
- * @iso: isosurface value.
- * @klass: a #GtsVertexClass.
- *
- * Fill @slice with the coordinates of the vertices defined by 
- * f1 (x,y,z) = @iso and f2 (x, y, z) = @iso.
- */
-void gts_iso_slice_fill_cartesian (GtsIsoSlice * slice,
-				   GtsCartesianGrid g,
-				   gdouble ** f1,
-				   gdouble ** f2,
-				   gdouble iso,
-				   GtsVertexClass * klass)
-{
-  OrientedVertex *** vertices;
-  guint i, j;
-  gdouble x, y;
-
-  g_return_if_fail (slice != NULL);
-  g_return_if_fail (f1 != NULL);
-
-  vertices = slice->vertices;
-
-  if (f2)
-    for (i = 0, x = g.x; i < g.nx; i++, x += g.dx)
-      for (j = 0, y = g.y; j < g.ny; j++, y += g.dy) {
-	gdouble v1 = f1[i][j] - iso;
-	gdouble v2 = f2[i][j] - iso;
-	if ((v1 >= 0. && v2 < 0.) || (v1 < 0. && v2 >= 0.)) {
-	  vertices[0][i][j].v = 
-	    gts_vertex_new (klass,
-			    x, y, g.z + g.dz*v1/(v1 - v2));
-	  vertices[0][i][j].orientation = v2 >= 0. ? RIGHT : LEFT;
-	}
-	else
-	  vertices[0][i][j].v = NULL;
-      }
-  for (i = 0, x = g.x; i < g.nx - 1; i++, x += g.dx)
-    for (j = 0, y = g.y; j < g.ny; j++, y += g.dy) {
-      gdouble v1 = f1[i][j] - iso;
-      gdouble v2 = f1[i+1][j] - iso;
-      if ((v1 >= 0. && v2 < 0.) || (v1 < 0. && v2 >= 0.)) {
-	vertices[1][i][j].v = 
-	  gts_vertex_new (klass, x + g.dx*v1/(v1 - v2), y, g.z);
-	vertices[1][i][j].orientation = v2 >= 0. ? RIGHT : LEFT;
-      }
-      else
-	vertices[1][i][j].v = NULL;
-    }
-  for (i = 0, x = g.x; i < g.nx; i++, x += g.dx)
-    for (j = 0, y = g.y; j < g.ny - 1; j++, y += g.dy) {
-      gdouble v1 = f1[i][j] - iso;
-      gdouble v2 = f1[i][j+1] - iso;
-      if ((v1 >= 0. && v2 < 0.) || (v1 < 0. && v2 >= 0.)) {
-	vertices[2][i][j].v = 
-	  gts_vertex_new (klass, x, y + g.dy*v1/(v1 - v2), g.z);
-	vertices[2][i][j].orientation = v2 >= 0. ? RIGHT : LEFT;
-      }
-      else
-	vertices[2][i][j].v = NULL;
-    }
-}
-
-/**
- * gts_iso_slice_destroy:
- * @slice: a #GtsIsoSlice.
- *
- * Free all memory allocated for @slice.
- */
-void gts_iso_slice_destroy (GtsIsoSlice * slice)
-{
-  g_return_if_fail (slice != NULL);
-
-  free2D ((void **) slice->vertices[0], slice->nx);
-  free2D ((void **) slice->vertices[1], slice->nx - 1);
-  free2D ((void **) slice->vertices[2], slice->nx);  
-  g_free (slice->vertices);
-  g_free (slice);
-}
-
-/**
- * gts_isosurface_slice:
- * @slice1: a #GtsIsoSlice.
- * @slice2: another #GtsIsoSlice.
- * @surface: a #GtsSurface.
- *
- * Given two successive slices @slice1 and @slice2 link their vertices with
- * segments and triangles which are added to @surface.
- */
-void gts_isosurface_slice (GtsIsoSlice * slice1,
-			   GtsIsoSlice * slice2,
-			   GtsSurface * surface)
-{
-  guint j, k, l, nx, ny;
-  OrientedVertex *** vertices[2];
-  GtsVertex * va[12];
-
-  g_return_if_fail (slice1 != NULL);
-  g_return_if_fail (slice2 != NULL);
-  g_return_if_fail (surface != NULL);
-  g_return_if_fail (slice1->nx == slice2->nx && slice1->ny == slice2->ny);
-
-  vertices[0] = slice1->vertices;
-  vertices[1] = slice2->vertices;
-  nx = slice1->nx;
-  ny = slice1->ny;
-
-  /* link vertices with segments and triangles */
-  for (j = 0; j < nx - 1; j++)
-    for (k = 0; k < ny - 1; k++) {
-      gboolean cube_is_cut = FALSE;
-      for (l = 0; l < 12; l++) {
-	guint nv = 0, e = l;
-	OrientedVertex ov = 
-	  vertices[c[e][1]][c[e][0]][j + c[e][2]][k + c[e][3]];
-	while (ov.v && !GTS_OBJECT (ov.v)->reserved) {
-	  guint m = 0, * ne = edge[e][ov.orientation];
-	  va[nv++] = ov.v;
-	  GTS_OBJECT (ov.v)->reserved = surface;
-	  ov.v = NULL;
-	  while (m < 3 && !ov.v) {
-	    e = ne[m++];
-	    ov = vertices[c[e][1]][c[e][0]][j + c[e][2]][k + c[e][3]];
-	  }
-	}
-	/* create edges and faces */
-	if (nv > 2) {
-	  GtsEdge * e1, * e2, * e3;
-	  guint m;
-	  if (!(e1 = GTS_EDGE (gts_vertices_are_connected (va[0], va[1]))))
-	    e1 = gts_edge_new (surface->edge_class, va[0], va[1]);
-	  for (m = 1; m < nv - 1; m++) {
-	    if (!(e2 = GTS_EDGE (gts_vertices_are_connected (va[m], va[m+1]))))
-	      e2 = gts_edge_new (surface->edge_class, va[m], va[m+1]);
-	    if (!(e3 = GTS_EDGE (gts_vertices_are_connected (va[m+1], va[0]))))
-	      e3 = gts_edge_new (surface->edge_class, va[m+1], va[0]);
-	    gts_surface_add_face (surface, 
-				  gts_face_new (surface->face_class,
-						e1, e2, e3));
-	    e1 = e3;
-	  }
-	}
-	if (nv > 0)
-	  cube_is_cut = TRUE;
-      }
-      if (cube_is_cut)
-	for (l = 0; l < 12; l++) {
-	  GtsVertex * v = 
-	    vertices[c[l][1]][c[l][0]][j + c[l][2]][k + c[l][3]].v;
-	  if (v)
-	    GTS_OBJECT (v)->reserved = NULL;
-	}
-    }
-}
-
-#define SWAP(s1, s2, tmp) (tmp = s1, s1 = s2, s2 = tmp)
-
-/**
- * gts_isosurface_cartesian:
- * @surface: a #GtsSurface.
- * @g: a #GtsCartesianGrid.
- * @f: a #GtsIsoCartesianFunc.
- * @data: user data to be passed to @f.
- * @iso: isosurface value.
- *
- * Adds to @surface new faces defining the isosurface f(x,y,z) = @iso. By
- * convention, the normals to the surface are pointing toward the positive
- * values of f(x,y,z) - @iso.
- *
- * The user function @f is called successively for each value of the z 
- * coordinate defined by @g. It must fill the corresponding (x,y) plane with
- * the values of the function for which the isosurface is to be computed.
- */
-void gts_isosurface_cartesian (GtsSurface * surface,
-			       GtsCartesianGrid g,
-			       GtsIsoCartesianFunc f,
-			       gpointer data,
-			       gdouble iso)
-{
-  void * tmp;
-  gdouble ** f1, ** f2;
-  GtsIsoSlice * slice1, * slice2;
-  guint i;
-
-  g_return_if_fail (surface != NULL);
-  g_return_if_fail (f != NULL);
-  g_return_if_fail (g.nx > 1);
-  g_return_if_fail (g.ny > 1);
-  g_return_if_fail (g.nz > 1);
-
-  slice1 = gts_iso_slice_new (g.nx, g.ny);
-  slice2 = gts_iso_slice_new (g.nx, g.ny);
-  f1 = (gdouble **) malloc2D (g.nx, g.ny, sizeof (gdouble));
-  f2 = (gdouble **) malloc2D (g.nx, g.ny, sizeof (gdouble));
-
-  (*f) (f1, g, 0, data);
-  g.z += g.dz;
-  (*f) (f2, g, 1, data);
-  g.z -= g.dz;
-  gts_iso_slice_fill_cartesian (slice1, g, f1, f2, iso, 
-				surface->vertex_class);
-  g.z += g.dz;
-  for (i = 2; i < g.nz; i++) {
-    g.z += g.dz;
-    (*f) (f1, g, i, data);
-    SWAP (f1, f2, tmp);
-    g.z -= g.dz;
-    gts_iso_slice_fill_cartesian (slice2, g, f1, f2, iso, 
-				  surface->vertex_class);
-    g.z += g.dz;
-    gts_isosurface_slice (slice1, slice2, surface);
-    SWAP (slice1, slice2, tmp);
-  }
-  gts_iso_slice_fill_cartesian (slice2, g, f2, NULL, iso,
-				surface->vertex_class);
-  gts_isosurface_slice (slice1, slice2, surface);
-
-  gts_iso_slice_destroy (slice1);
-  gts_iso_slice_destroy (slice2);
-  free2D ((void **) f1, g.nx);
-  free2D ((void **) f2, g.nx);
-}
diff --git a/src/gts/isotetra.c b/src/gts/isotetra.c
deleted file mode 100644
index 35fe2ba..0000000
--- a/src/gts/isotetra.c
+++ /dev/null
@@ -1,840 +0,0 @@
-/* GTS-Library conform marching tetrahedra algorithm 
- * Copyright (C) 2002 Gert Wollny
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <math.h>
-#include <string.h>
-#include <gts.h>
-#ifdef NATIVE_WIN32
-# include <memory.h>
-# define M_SQRT2		1.41421356237309504880
-#endif /* NATIVE_WIN32 */
-
-typedef struct {
-  gint nx, ny; 
-  gdouble ** data; 
-} slice_t;
-
-typedef struct {
-  gint x, y, z;
-  gboolean mid;
-  gdouble d; 
-} tetra_vertex_t; 
-
-/* this helper is a lookup table for vertices */
-typedef struct {
-  gint nx, ny; 
-  GtsVertex ** vtop, ** vmid, **vbot;
-} helper_t ;
-
-typedef struct {
-  GHashTable * vbot, * vtop;
-} helper_bcl ;
-
-
-static helper_t * init_helper (int nx, int ny) 
-{
-  gint nxy = 4*nx*ny; 
-  helper_t *retval = g_malloc0 (sizeof (helper_t));
-
-  retval->nx = nx; 
-  retval->ny = ny; 
-  retval->vtop = g_malloc0 (sizeof (GtsVertex *)*nxy);
-  retval->vmid = g_malloc0 (sizeof (GtsVertex *)*nxy);
-  retval->vbot = g_malloc0 (sizeof (GtsVertex *)*nxy);
-  return retval;
-}
-
-static helper_bcl * init_helper_bcl (void)
-{
-  helper_bcl *retval = g_malloc0 (sizeof (helper_bcl));
-
-  retval->vtop = g_hash_table_new (g_str_hash, g_str_equal);
-  retval->vbot = g_hash_table_new (g_str_hash, g_str_equal);
-  return retval;
-}
-
-static void free_helper (helper_t * h) 
-{
-  g_free (h->vtop);
-  g_free (h->vmid);
-  g_free (h->vbot);
-  g_free (h);
-}
-
-static void free_helper_bcl (helper_bcl * h) 
-{
-  g_hash_table_destroy (h->vtop);
-  g_hash_table_destroy (h->vbot);
-  g_free (h);
-}
-
-/* move the vertices in the bottom slice to the top, and clear the
-   other slices in the lookup tables */
-static void helper_advance (helper_t * h) 
-{
-  GtsVertex ** help = h->vbot;
-  h->vbot = h->vtop; 
-  h->vtop = help;
-  
-  memset (h->vmid, 0, 4*sizeof(GtsVertex *) * h->nx * h->ny);
-  memset (h->vbot, 0, 4*sizeof(GtsVertex *) * h->nx * h->ny);
-}
-
-static void helper_advance_bcl (helper_bcl * h) 
-{
-  GHashTable * help = g_hash_table_new (g_str_hash, g_str_equal);
-
-  g_hash_table_destroy (h->vbot);
-  h->vbot = h->vtop;
-  h->vtop = help;
-}
-
-/* find the zero-crossing of line through v1 and v2 and return the
-   corresponding GtsVertex */
-static GtsVertex * get_vertex (gint mz, 
-			       const tetra_vertex_t * v1, 
-			       const tetra_vertex_t * v2, 
-			       helper_t * help, 
-			       GtsCartesianGrid * g,
-			       GtsVertexClass * klass)
-{
-  GtsVertex ** vertex; 
-  gint x, y, index, idx2, z; 
-  gdouble dx, dy, dz, d; 
-
-  g_assert (v1->d - v2->d != 0.);
-  
-  dx = dy = dz = 0.0;
-  d = v1->d/(v1->d - v2->d);
-
-  index = 0;
-  
-  if (v1->x != v2->x) {
-    index |= 1;
-    dx = d;
-  }
-  
-  if (v1->y != v2->y) {
-    index |= 2;
-    dy = d;
-  }
-  
-  if (v1->z != v2->z) {
-    dz = d;
-  }
-
-  x = v1->x;
-  if (v1->x > v2->x) {  x = v2->x; dx = 1.0 - dx; }
-  
-  y = v1->y;
-  if (v1->y > v2->y) {  y = v2->y; dy = 1.0 - dy;}
-  
-  z = v1->z;
-  if (v1->z > v2->z) {  z = v2->z; dz = 1.0 - dz;}
-  
-  idx2 = 4 * ( x + y * help->nx ) + index;
-  
-  if (v1->z == v2->z)
-    vertex = (mz == z) ? &help->vtop[idx2] : &help->vbot[idx2];
-  else
-    vertex = &help->vmid[idx2];
-  
-  if (mz != z && dz != 0.0) {
-    fprintf(stderr, "%f \n", dz);
-  }
-  
-  /* if vertex is not yet created, do it now */
-  if (!*vertex)
-    *vertex = gts_vertex_new (klass,
-			      g->dx * ( x + dx) + g->x, 
-			      g->dy * ( y + dy) + g->y, 
-			      g->dz * ( z + dz) + g->z);
-  
-  return *vertex;
-}
-
-static GtsVertex * get_vertex_bcl (gint mz, 
-				   const tetra_vertex_t * v1, 
-				   const tetra_vertex_t * v2, 
-				   helper_bcl * help, 
-				   GtsCartesianGrid * g,
-				   GtsVertexClass * klass)
-{
-  GtsVertex * v;
-  GHashTable * table;
-  gchar * s1, * s2, * hash;
-  gdouble x1, x2, y1, y2, z1, z2, d;
-
-  g_assert (v1->d - v2->d != 0.);
-
-  /* first find correct hash table */  
-  if ((v1->z > mz) && (v2->z > mz))
-    table = help->vtop;
-  else
-    table = help->vbot;
-
-  d = v1->d / (v1->d - v2->d);
-
-  /* sort vertices */
-  s1 = g_strdup_printf ("%d %d %d %d", v1->x, v1->y, v1->z, v1->mid);
-  s2 = g_strdup_printf ("%d %d %d %d", v2->x, v2->y, v2->z, v2->mid);
-
-  hash = (d == 0.0) ? g_strdup (s1) :
-    (d == 1.0) ? g_strdup (s2) :
-    (strcmp (s1, s2) < 0) ? g_strjoin (" ", s1, s2, NULL) :
-    g_strjoin (" ", s2, s1, NULL);
-
-  /* return existing vertex or make a new one */
-  v = g_hash_table_lookup (table, hash);
-  if (!v){
-
-    x1 = g->dx * (v1->x + (v1->mid / 2.0)) + g->x;
-    x2 = g->dx * (v2->x + (v2->mid / 2.0)) + g->x;
-    y1 = g->dy * (v1->y + (v1->mid / 2.0)) + g->y;
-    y2 = g->dy * (v2->y + (v2->mid / 2.0)) + g->y;
-    z1 = g->dz * (v1->z + (v1->mid / 2.0)) + g->z;
-    z2 = g->dz * (v2->z + (v2->mid / 2.0)) + g->z;
-
-    v = gts_vertex_new (klass, x1 * (1.0 - d) + d * x2,
-			y1 * (1.0 - d) + d * y2,
-			z1 * (1.0 - d) + d * z2);
-
-    g_hash_table_insert (table, g_strdup(hash), v);
-  }
-  g_free (s1);
-  g_free (s2);
-  g_free (hash);
-
-  return v;
-}
-
-/* create an edge connecting the zero crossings of lines through a
-   pair of vertices, or return an existing one */
-static GtsEdge * get_edge (GtsVertex * v1, GtsVertex * v2,
-			   GtsEdgeClass * klass)
-{
-  GtsSegment *s;
-  GtsEdge *edge; 
-  
-  g_assert (v1);
-  g_assert (v2);
-  
-  s = gts_vertices_are_connected (v1, v2);
-  
-  if (GTS_IS_EDGE (s))
-    edge = GTS_EDGE(s);
-  else
-    edge = gts_edge_new (klass, v1, v2);
-  return edge; 
-}
-
-static void add_face (GtsSurface * surface, 
-		      const tetra_vertex_t * a1, const tetra_vertex_t * a2, 
-		      const tetra_vertex_t * b1, const tetra_vertex_t * b2, 
-		      const tetra_vertex_t * c1, const tetra_vertex_t * c2, 
-		      gint rev, helper_t * help, 
-		      gint z, GtsCartesianGrid * g)
-{
-  GtsFace * t; 
-  GtsEdge * e1, * e2, * e3; 	
-  GtsVertex * v1 = get_vertex (z, a1, a2, help, g, surface->vertex_class);
-  GtsVertex * v2 = get_vertex (z, b1, b2, help, g, surface->vertex_class);
-  GtsVertex * v3 = get_vertex (z, c1, c2, help, g, surface->vertex_class);
-
-  g_assert (v1 != v2);
-  g_assert (v2 != v3);
-  g_assert (v1 != v3);
-
-  if (!rev) {
-    e1 = get_edge (v1, v2, surface->edge_class);
-    e2 = get_edge (v2, v3, surface->edge_class);
-    e3 = get_edge (v1, v3, surface->edge_class);
-  } else {
-    e1 = get_edge (v1, v3, surface->edge_class);
-    e2 = get_edge (v2, v3, surface->edge_class);
-    e3 = get_edge (v1, v2, surface->edge_class);	
-  }
-  
-  t = gts_face_new (surface->face_class, e1, e2, e3);	
-  gts_surface_add_face (surface, t);
-}
-
-static void add_face_bcl (GtsSurface * surface, 
-			  const tetra_vertex_t * a1, 
-			  const tetra_vertex_t * a2, 
-			  const tetra_vertex_t * b1, 
-			  const tetra_vertex_t * b2, 
-			  const tetra_vertex_t * c1, 
-			  const tetra_vertex_t * c2, 
-			  gint rev, helper_bcl * help, 
-			  gint z, GtsCartesianGrid * g)
-{
-  GtsFace * t; 
-  GtsEdge * e1, * e2, * e3; 	
-  GtsVertex * v1 = get_vertex_bcl (z, a1, a2, help, g, surface->vertex_class);
-  GtsVertex * v2 = get_vertex_bcl (z, b1, b2, help, g, surface->vertex_class);
-  GtsVertex * v3 = get_vertex_bcl (z, c1, c2, help, g, surface->vertex_class);
-
-  if (v1 == v2 || v2 == v3 || v1 == v3)
-    return;
-
-  if (!rev) {
-    e1 = get_edge (v1, v2, surface->edge_class);
-    e2 = get_edge (v2, v3, surface->edge_class);
-    e3 = get_edge (v1, v3, surface->edge_class);
-  } else {
-    e1 = get_edge (v1, v3, surface->edge_class);
-    e2 = get_edge (v2, v3, surface->edge_class);
-    e3 = get_edge (v1, v2, surface->edge_class);	
-  }
-
-  t = gts_face_new (surface->face_class, e1, e2, e3);	
-  gts_surface_add_face (surface, t);
-}
-
-/* create a new slice of site nx \times ny */
-static slice_t * new_slice (gint nx, gint ny) 
-{
-  gint x; 
-  slice_t * retval = g_malloc (sizeof (slice_t));
-
-  retval->data = g_malloc (nx*sizeof(gdouble *));
-  retval->nx = nx;
-  retval->ny = ny;  
-  for (x = 0; x < nx; x++) 
-    retval->data[x] = g_malloc (ny*sizeof (gdouble));
-  return retval; 
-}
-
-/* initialize a slice with inival */
-static void slice_init (slice_t * slice, gdouble inival)
-{
-  gint x, y; 
-  
-  g_assert (slice);
-	
-  for (x = 0; x < slice->nx; x++) 
-    for (y = 0; y < slice->ny; y++)
-      slice->data[x][y] = inival; 
-}
-
-/* free the memory of a slice */
-static void free_slice (slice_t * slice) 
-{
-  gint x; 
-	
-  g_return_if_fail (slice != NULL);
-	
-  for (x = 0; x < slice->nx; x++) 
-    g_free (slice->data[x]);  
-  g_free (slice->data);
-  g_free (slice);
-}
-
-static void analyze_tetrahedra (const tetra_vertex_t * a, 
-				const tetra_vertex_t * b, 
-				const tetra_vertex_t * c, 
-				const tetra_vertex_t * d, 
-				gint parity, GtsSurface * surface, 
-				helper_t * help, 
-				gint z, GtsCartesianGrid * g)
-{
-  gint rev = parity; 
-  gint code = 0; 
-	
-  if (a->d >= 0.) code |= 1; 
-  if (b->d >= 0.) code |= 2; 
-  if (c->d >= 0.) code |= 4; 
-  if (d->d >= 0.) code |= 8;
-		
-  switch (code) {
-  case 15:
-  case 0: return; /* all inside or outside */		
-  
-  case 14:rev = !parity;
-  case  1:add_face (surface, a, b, a, d, a, c, rev, help, z, g);
-	  break;
-  case 13:rev = ! parity;  
-  case  2:add_face (surface, a, b, b, c, b, d, rev, help, z, g);
-	  break;
-  case 12:rev = !parity;	  
-  case  3:add_face (surface, a, d, a, c, b, c, rev, help, z, g);
-	  add_face (surface, a, d, b, c, b, d, rev, help, z, g);
-	  break;
-  case 11:rev = !parity;	  
-  case  4:add_face (surface, a, c, c, d, b, c, rev, help, z, g);
-	  break;
-  case 10:rev = !parity; 	  
-  case 5: add_face (surface, a, b, a, d, c, d, rev, help, z, g);
-	  add_face (surface, a, b, c, d, b, c, rev, help, z, g);
-	  break;	
-  case  9:rev = !parity; 
-  case  6:add_face (surface, a, b, a, c, c, d, rev, help, z, g);
-	  add_face (surface, a, b, c, d, b, d, rev, help, z, g);
-	  break;
-  case  7:rev = !parity;
-  case  8:add_face (surface, a, d, b, d, c, d, rev, help, z, g);
-    break; 
-  }
-}
-
-static void analyze_tetrahedra_bcl (const tetra_vertex_t * a, 
-				    const tetra_vertex_t * b, 
-				    const tetra_vertex_t * c, 
-				    const tetra_vertex_t * d, 
-				    GtsSurface * surface, 
-				    helper_bcl * help, 
-				    gint z, GtsCartesianGrid * g)
-{
-  gint rev = 0;
-  gint code = 0; 
-	
-  if (a->d >= 0.) code |= 1; 
-  if (b->d >= 0.) code |= 2; 
-  if (c->d >= 0.) code |= 4; 
-  if (d->d >= 0.) code |= 8;
-
-  switch (code) {
-  case 15:
-  case 0: return; /* all inside or outside */		
-
-  case 14:rev = !rev;
-  case  1:add_face_bcl (surface, a, b, a, d, a, c, rev, help, z, g);
-	  break;
-  case 13:rev = !rev;  
-  case  2:add_face_bcl (surface, a, b, b, c, b, d, rev, help, z, g);
-	  break;
-  case 12:rev = !rev;	  
-  case  3:add_face_bcl (surface, a, d, a, c, b, c, rev, help, z, g);
-	  add_face_bcl (surface, a, d, b, c, b, d, rev, help, z, g);
-	  break;
-  case 11:rev = !rev;	  
-  case  4:add_face_bcl (surface, a, c, c, d, b, c, rev, help, z, g);
-	  break;
-  case 10:rev = !rev; 	  
-  case 5: add_face_bcl (surface, a, b, a, d, c, d, rev, help, z, g);
-	  add_face_bcl (surface, a, b, c, d, b, c, rev, help, z, g);
-	  break;	
-  case  9:rev = !rev; 
-  case  6:add_face_bcl (surface, a, b, a, c, c, d, rev, help, z, g);
-	  add_face_bcl (surface, a, b, c, d, b, d, rev, help, z, g);
-	  break;
-  case  7:rev = !rev;
-  case  8:add_face_bcl (surface, a, d, b, d, c, d, rev, help, z, g);
-    break;
-  }
-}
-
-static void  iso_slice_evaluate (slice_t * s1, slice_t * s2, 
-				 GtsCartesianGrid g, 
-				 gint z, GtsSurface * surface, helper_t * help)
-{
-  gint x,y; 
-  tetra_vertex_t v0, v1, v2, v3, v4, v5, v6, v7; 
-  gdouble ** s1p = s1->data; 
-  gdouble ** s2p = s2->data; 
-	
-  for (y = 0; y < g.ny-1; y++)
-    for (x = 0; x < g.nx-1; x++) {
-      gint parity = (((x ^ y) ^ z) & 1);
-      
-      v0.x = x  ; v0.y = y  ; v0.z = z  ; v0.mid = FALSE; v0.d = s1p[x  ][y  ];
-      v1.x = x  ; v1.y = y+1; v1.z = z  ; v1.mid = FALSE; v1.d = s1p[x  ][y+1];
-      v2.x = x+1; v2.y = y  ; v2.z = z  ; v2.mid = FALSE; v2.d = s1p[x+1][y  ];
-      v3.x = x+1; v3.y = y+1; v3.z = z  ; v3.mid = FALSE; v3.d = s1p[x+1][y+1];
-      v4.x = x  ; v4.y = y  ; v4.z = z+1; v4.mid = FALSE; v4.d = s2p[x  ][y  ];
-      v5.x = x  ; v5.y = y+1; v5.z = z+1; v5.mid = FALSE; v5.d = s2p[x  ][y+1];
-      v6.x = x+1; v6.y = y  ; v6.z = z+1; v6.mid = FALSE; v6.d = s2p[x+1][y  ];
-      v7.x = x+1; v7.y = y+1; v7.z = z+1; v7.mid = FALSE; v7.d = s2p[x+1][y+1];
-      
-      if (parity == 0) {
-	analyze_tetrahedra (&v0, &v1, &v2, &v4, parity, surface, help, z, &g);
-	analyze_tetrahedra (&v7, &v1, &v4, &v2, parity, surface, help, z, &g);
-	analyze_tetrahedra (&v1, &v7, &v3, &v2, parity, surface, help, z, &g);
-	analyze_tetrahedra (&v1, &v7, &v4, &v5, parity, surface, help, z, &g);
-	analyze_tetrahedra (&v2, &v6, &v4, &v7, parity, surface, help, z, &g);
-      }else{
-	analyze_tetrahedra (&v4, &v5, &v6, &v0, parity, surface, help, z, &g);
-	analyze_tetrahedra (&v3, &v5, &v0, &v6, parity, surface, help, z, &g);
-	analyze_tetrahedra (&v5, &v3, &v7, &v6, parity, surface, help, z, &g);
-	analyze_tetrahedra (&v5, &v3, &v0, &v1, parity, surface, help, z, &g);
-	analyze_tetrahedra (&v6, &v2, &v0, &v3, parity, surface, help, z, &g);
-      }
-    }
-}
-
-static void  iso_slice_evaluate_bcl (slice_t * s1, slice_t * s2, slice_t * s3,
-				     GtsCartesianGrid g, 
-				     gint z, GtsSurface * surface, 
-				     helper_bcl * help)
-{
-  gint x,y; 
-  tetra_vertex_t v0, v1, v2, v3, v4, v5, v6, v7, v8, v9, w0; 
-  gdouble ** s1p = s1->data;
-  gdouble ** s2p = s2->data;
-  gdouble ** s3p = s3->data;
-	
-  for (y = 0; y < g.ny-2; y++)
-    for (x = 0; x < g.nx-2; x++) {
-      v0.x = x  ; v0.y = y  ; v0.z = z  ; v0.mid = TRUE;
-      v0.d = (s1p[x  ][y  ] + s2p[x  ][y  ] +
-	      s1p[x  ][y+1] + s2p[x  ][y+1] +
-	      s1p[x+1][y  ] + s2p[x+1][y  ] +
-	      s1p[x+1][y+1] + s2p[x+1][y+1])/8.0;
-
-      v1.x = x+1; v1.y = y  ; v1.z = z  ; v1.mid = TRUE;
-      v1.d = (s1p[x+1][y  ] + s2p[x+1][y  ] +
-	      s1p[x+1][y+1] + s2p[x+1][y+1] +
-	      s1p[x+2][y  ] + s2p[x+2][y  ] +
-	      s1p[x+2][y+1] + s2p[x+2][y+1])/8.0;
-
-      v2.x = x  ; v2.y = y+1; v2.z = z  ; v2.mid = TRUE;
-      v2.d = (s1p[x  ][y+1] + s2p[x  ][y+1] +
-	      s1p[x  ][y+2] + s2p[x  ][y+2] +
-	      s1p[x+1][y+1] + s2p[x+1][y+1] +
-	      s1p[x+1][y+2] + s2p[x+1][y+2])/8.0;
-
-      v3.x = x  ; v3.y = y  ; v3.z = z+1; v3.mid = TRUE;
-      v3.d = (s2p[x  ][y  ] + s3p[x  ][y  ] +
-	      s2p[x  ][y+1] + s3p[x  ][y+1] +
-	      s2p[x+1][y  ] + s3p[x+1][y  ] +
-	      s2p[x+1][y+1] + s3p[x+1][y+1])/8.0;
-
-      v4.x = x+1; v4.y = y  ; v4.z = z  ; v4.mid = FALSE; v4.d = s1p[x+1][y  ];
-      v5.x = x  ; v5.y = y+1; v5.z = z  ; v5.mid = FALSE; v5.d = s1p[x  ][y+1];
-      v6.x = x+1; v6.y = y+1; v6.z = z  ; v6.mid = FALSE; v6.d = s1p[x+1][y+1];
-      v7.x = x+1; v7.y = y  ; v7.z = z+1; v7.mid = FALSE; v7.d = s2p[x+1][y  ];
-      v8.x = x  ; v8.y = y+1; v8.z = z+1; v8.mid = FALSE; v8.d = s2p[x  ][y+1];
-      v9.x = x+1; v9.y = y+1; v9.z = z+1; v9.mid = FALSE; v9.d = s2p[x+1][y+1];
-      w0.x = x  ; w0.y = y  ; w0.z = z+1; w0.mid = FALSE; w0.d = s2p[x  ][y  ];
-
-      analyze_tetrahedra_bcl (&v0, &v9, &v6, &v1, surface, help, z, &g);
-      analyze_tetrahedra_bcl (&v0, &v6, &v4, &v1, surface, help, z, &g);
-      analyze_tetrahedra_bcl (&v0, &v4, &v7, &v1, surface, help, z, &g);
-      analyze_tetrahedra_bcl (&v0, &v7, &v9, &v1, surface, help, z, &g);
-      analyze_tetrahedra_bcl (&v0, &v5, &v6, &v2, surface, help, z, &g);
-      analyze_tetrahedra_bcl (&v0, &v6, &v9, &v2, surface, help, z, &g);
-      analyze_tetrahedra_bcl (&v0, &v9, &v8, &v2, surface, help, z, &g);
-      analyze_tetrahedra_bcl (&v0, &v8, &v5, &v2, surface, help, z, &g);
-      analyze_tetrahedra_bcl (&v0, &v8, &v9, &v3, surface, help, z, &g);
-      analyze_tetrahedra_bcl (&v0, &v9, &v7, &v3, surface, help, z, &g);
-      analyze_tetrahedra_bcl (&v0, &v7, &w0, &v3, surface, help, z, &g);
-      analyze_tetrahedra_bcl (&v0, &w0, &v8, &v3, surface, help, z, &g);
-    }
-}
-
-/*  copy src into dest by stripping off the iso value and leave out
-    the boundary (which should be G_MINDOUBLE) */
-static void copy_to_bounded (slice_t * dest, slice_t * src, 
-			     gdouble iso, gdouble fill)
-{
-  gint x,y; 
-  gdouble * src_ptr;
-  gdouble * dest_ptr = dest->data[0];
-  
-  g_assert(dest->ny == src->ny + 2);
-  g_assert(dest->nx == src->nx + 2);
-	
-  for (y = 0; y < dest->ny; ++y, ++dest_ptr)
-    *dest_ptr = fill; 
-	
-  for (x = 1; x < src->nx - 1; ++x) {
-    dest_ptr = dest->data[x];
-    src_ptr = src->data[x-1];
-    *dest_ptr++ = fill;
-    for (y = 0; y < src->ny; ++y, ++dest_ptr, ++src_ptr)
-      *dest_ptr  = *src_ptr - iso;
-    *dest_ptr++ = fill; 
-  }
-  
-  dest_ptr = dest->data[y];
-  
-  for (y = 0; y < dest->ny; ++y, ++dest_ptr)
-    *dest_ptr = fill; 
-}
-
-static void iso_sub (slice_t * s, gdouble iso)
-{
-  gint x,y; 
-
-  for (x = 0; x < s->nx; ++x) {
-    gdouble *ptr = s->data[x];
-
-    for (y = 0; y < s->ny; ++y, ++ptr)
-      *ptr -= iso; 
-  }
-}
-
-
-/**
- * gts_isosurface_tetra_bounded:
- * @surface: a #GtsSurface.
- * @g: a #GtsCartesianGrid.
- * @f: a #GtsIsoCartesianFunc.
- * @data: user data to be passed to @f.
- * @iso: isosurface value.
- *
- * Adds to @surface new faces defining the isosurface f(x,y,z) =
- * @iso. By convention, the normals to the surface are pointing toward
- * the positive values of f(x,y,z) - @iso. To ensure a closed object,
- * a boundary of G_MINDOUBLE is added around the domain
- *
- * The user function @f is called successively for each value of the z
- * coordinate defined by @g. It must fill the corresponding (x,y)
- * plane with the values of the function for which the isosurface is
- * to be computed.  
- */
-void gts_isosurface_tetra_bounded (GtsSurface * surface,
-				   GtsCartesianGrid g,
-				   GtsIsoCartesianFunc f,
-				   gpointer data,
-				   gdouble iso)
-{
-  slice_t *slice1, *slice2, *transfer_slice; 
-  GtsCartesianGrid g_intern = g; 
-  helper_t *helper;
-  gint z; 
-	
-  g_return_if_fail (surface != NULL);
-  g_return_if_fail (f != NULL);
-  g_return_if_fail (g.nx > 1);
-  g_return_if_fail (g.ny > 1);
-  g_return_if_fail (g.nz > 1);
-
-  /* create the helper slices */
-  slice1 = new_slice (g.nx + 2, g.ny + 2);
-  slice2 = new_slice (g.nx + 2, g.ny + 2);
-	
-  /*  initialize the first slice as OUTSIDE */
-  slice_init (slice1, -1.0);
-	
-  /* create a slice of the original image size */
-  transfer_slice = new_slice (g.nx, g.ny);
-	
-  /* adapt the parameters to our enlarged image */
-  g_intern.x -= g.dx;
-  g_intern.y -= g.dy; 
-  g_intern.z -= g.dz;
-  g_intern.nx = g.nx + 2;
-  g_intern.ny = g.ny + 2; 	
-  g_intern.nz = g.nz;
-	
-  /* create the helper for vertex-lookup */
-  helper = init_helper (g_intern.nx, g_intern.ny);
-	
-  /* go slicewise through the data */
-  z = 0; 
-  while (z < g.nz) {
-    slice_t * hs; 
-    
-    /* request slice */
-    f (transfer_slice->data, g, z, data);
-    g.z += g.dz; 
-    
-    /* copy slice in enlarged image and mark the border as OUTSIDE */
-    copy_to_bounded (slice2, transfer_slice, iso, -1.);
-    
-    /* triangulate */
-    iso_slice_evaluate (slice1, slice2, g_intern, z, surface, helper);
-    
-    /* switch the input slices */
-    hs = slice1; slice1 = slice2; slice2 = hs; 
-    
-    /* switch the vertex lookup tables */
-    helper_advance(helper);
-    ++z; 
-  }
-  
-  /* initialize the last slice as OUTSIDE */
-  slice_init (slice2, - 1.0);
-		
-  /* close the object */
-  iso_slice_evaluate(slice1, slice2, g_intern, z, surface, helper);
-  
-  free_helper (helper);
-  free_slice (slice1);
-  free_slice (slice2);
-  free_slice (transfer_slice);	
-}
-
-/**
- * gts_isosurface_tetra:
- * @surface: a #GtsSurface.
- * @g: a #GtsCartesianGrid.
- * @f: a #GtsIsoCartesianFunc.
- * @data: user data to be passed to @f.
- * @iso: isosurface value.
- *
- * Adds to @surface new faces defining the isosurface f(x,y,z) =
- * @iso. By convention, the normals to the surface are pointing toward
- * the positive values of f(x,y,z) - @iso.
- *
- * The user function @f is called successively for each value of the z
- * coordinate defined by @g. It must fill the corresponding (x,y)
- * plane with the values of the function for which the isosurface is
- * to be computed.  
- */
-void gts_isosurface_tetra (GtsSurface * surface,
-			   GtsCartesianGrid g,
-			   GtsIsoCartesianFunc f,
-			   gpointer data,
-			   gdouble iso)
-{
-  slice_t *slice1, *slice2; 
-  helper_t *helper;
-  gint z; 
-  GtsCartesianGrid g_internal;
-  
-  g_return_if_fail (surface != NULL);
-  g_return_if_fail (f != NULL);
-  g_return_if_fail (g.nx > 1);
-  g_return_if_fail (g.ny > 1);
-  g_return_if_fail (g.nz > 1);
-
-  memcpy (&g_internal, &g, sizeof (GtsCartesianGrid));
-	
-  /* create the helper slices */
-  slice1 = new_slice (g.nx, g.ny);
-  slice2 = new_slice (g.nx, g.ny);
-  
-  /* create the helper for vertex-lookup */
-  helper = init_helper (g.nx, g.ny);
-	
-  z = 0;
-  f (slice1->data, g, z, data);
-  iso_sub (slice1, iso); 
-  
-  z++; 
-  g.z += g.dz;
-  
-  /* go slicewise through the data */
-  while (z < g.nz) {
-    slice_t * hs; 
-    
-    /* request slice */
-    f (slice2->data, g, z, data);
-    iso_sub (slice2, iso);
-     
-    g.z += g.dz;
-    
-    /* triangulate */
-    iso_slice_evaluate (slice1, slice2, g_internal, z-1, surface, helper);
-    
-    /* switch the input slices */
-    hs = slice1; slice1 = slice2; slice2 = hs; 
-    
-    /* switch the vertex lookup tables */
-    helper_advance (helper);
-    
-    ++z; 
-  }
-
-  free_helper(helper);
-  free_slice(slice1);
-  free_slice(slice2);	
-}
-
-/**
- * gts_isosurface_tetra_bcl:
- * @surface: a #GtsSurface.
- * @g: a #GtsCartesianGrid.
- * @f: a #GtsIsoCartesianFunc.
- * @data: user data to be passed to @f.
- * @iso: isosurface value.
- *
- * Adds to @surface new faces defining the isosurface f(x,y,z) =
- * @iso. By convention, the normals to the surface are pointing toward
- * the positive values of f(x,y,z) - @iso.
- *
- * The user function @f is called successively for each value of the z
- * coordinate defined by @g. It must fill the corresponding (x,y)
- * plane with the values of the function for which the isosurface is
- * to be computed.  
- *
- * This version produces the dual "body-centered" faces relative to
- * the faces produced by gts_isosurface_tetra().
- */
-void gts_isosurface_tetra_bcl (GtsSurface * surface,
-			       GtsCartesianGrid g,
-			       GtsIsoCartesianFunc f,
-			       gpointer data,
-			       gdouble iso)
-{
-  slice_t *slice1, *slice2, *slice3;
-  helper_bcl *helper;
-  gint z; 
-  GtsCartesianGrid g_internal;
-  
-  g_return_if_fail (surface != NULL);
-  g_return_if_fail (f != NULL);
-  g_return_if_fail (g.nx > 1);
-  g_return_if_fail (g.ny > 1);
-  g_return_if_fail (g.nz > 1);
-
-  memcpy (&g_internal, &g, sizeof (GtsCartesianGrid));
-	
-  /* create the helper slices */
-  slice1 = new_slice (g.nx, g.ny);
-  slice2 = new_slice (g.nx, g.ny);
-  slice3 = new_slice (g.nx, g.ny);
-  
-  /* create the helper for vertex-lookup */
-  helper = init_helper_bcl ();
-	
-  z = 0;
-  f (slice1->data, g, z, data);
-  iso_sub (slice1, iso); 
-
-  z++; 
-  g.z += g.dz;
-
-  f (slice2->data, g, z, data);
-  iso_sub (slice1, iso); 
-  
-  z++; 
-  g.z += g.dz;
-  
-  /* go slicewise through the data */
-  while (z < g.nz) {
-    slice_t * hs; 
-    
-    /* request slice */
-    f (slice3->data, g, z, data);
-    iso_sub (slice3, iso);
-     
-    g.z += g.dz;
-    
-    /* triangulate */
-    iso_slice_evaluate_bcl (slice1, slice2, slice3, g_internal, z-2, 
-			    surface, helper);
-    
-    /* switch the input slices */
-    hs = slice1; slice1 = slice2; slice2 = slice3; slice3 = hs;
-    
-    /* switch the vertex lookup tables */
-    helper_advance_bcl (helper);
-    
-    ++z; 
-  }
-
-  free_helper_bcl(helper);
-  free_slice(slice1);
-  free_slice(slice2);	
-  free_slice(slice3);	
-}
diff --git a/src/gts/kdtree.c b/src/gts/kdtree.c
deleted file mode 100644
index ec5d422..0000000
--- a/src/gts/kdtree.c
+++ /dev/null
@@ -1,152 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <stdlib.h>
-#include "gts.h"
-
-
-static int compare_x (const void * p1, const void * p2) {
-  GtsPoint 
-    * pp1 = *((gpointer *) p1),
-    * pp2 = *((gpointer *) p2);
-  if (pp1->x > pp2->x)
-    return 1;
-  return -1;
-}
-
-static int compare_y (const void * p1, const void * p2) {
-  GtsPoint
-    * pp1 = *((gpointer *) p1),
-    * pp2 = *((gpointer *) p2);
-  if (pp1->y > pp2->y)
-    return 1;
-  return -1;
-}
-
-static int compare_z (const void * p1, const void * p2) {
-  GtsPoint 
-    * pp1 = *((gpointer *) p1),
-    * pp2 = *((gpointer *) p2);
-  if (pp1->z > pp2->z)
-    return 1;
-  return -1;
-}
-
-/**
- * gts_kdtree_new:
- * @points: an array of #GtsPoint.
- * @compare: always %NULL.
- *
- * Note that the order of the points in array @points is modified by this
- * function.
- * 
- * Returns: a new 3D tree for @points.
- */
-GNode * gts_kdtree_new (GPtrArray * points, 
-			int (*compare) (const void *, const void *))
-{
-  guint middle;
-  GPtrArray array;
-  GNode * node;
-  GtsPoint * point;
-
-  g_return_val_if_fail (points != NULL, NULL);
-  g_return_val_if_fail (points->len > 0, NULL);
-
-  /* sort the points */
-  if (compare == compare_x) compare = compare_y;
-  else if (compare == compare_y) compare = compare_z;
-  else compare = compare_x;
-  qsort (points->pdata, points->len, sizeof (gpointer), compare);
-
-  middle = (points->len - 1)/2;
-  point = points->pdata[middle];
-  node = g_node_new (point);
-
-  if (points->len > 1) {
-    array.len = middle;
-    if (array.len > 0) {
-      array.pdata = points->pdata;
-      g_node_prepend (node, gts_kdtree_new (&array, compare));
-    }
-    else
-      g_node_prepend (node, g_node_new (NULL));
-    
-    array.len = points->len - middle - 1;
-    if (array.len > 0) {
-      array.pdata = &(points->pdata[middle + 1]);
-      g_node_prepend (node, gts_kdtree_new (&array, compare));
-    }
-    else
-      g_node_prepend (node, g_node_new (NULL));
-  }
-
-  return node;
-}
-
-/**
- * gts_kdtree_range:
- * @tree: a 3D tree.
- * @bbox: a #GtsBBox.
- * @compare: always %NULL.
- *
- * Returns: a list of #GtsPoint belonging to @tree which are inside @bbox.
- */
-GSList * gts_kdtree_range (GNode * tree_3d,
-			   GtsBBox * bbox,
-			   int (*compare) (const void *, const void *))
-{
-  GSList * list = NULL;
-  GtsPoint * p;
-  gdouble left, right, v;
-  GNode * node;
-
-  g_return_val_if_fail (tree_3d != NULL, NULL);
-  g_return_val_if_fail (bbox != NULL, NULL);
-
-  p = tree_3d->data;
-  if (p == NULL)
-    return NULL;
-
-  if (gts_bbox_point_is_inside (bbox, p))
-    list = g_slist_prepend (list, p);
-
-  if (compare == compare_x) {
-    left = bbox->y1; right = bbox->y2; v = p->y;
-    compare = compare_y;
-  }
-  else if (compare == compare_y) {
-    left = bbox->z1; right = bbox->z2; v = p->z;
-    compare = compare_z;
-  }
-  else {
-    left = bbox->x1; right = bbox->x2; v = p->x;
-    compare = compare_x;
-  }
-
-  if ((node = tree_3d->children)) {
-    if (right >= v)
-      list = g_slist_concat (list, gts_kdtree_range (node, bbox, compare));
-    node = node->next;
-    if (left <= v)
-      list = g_slist_concat (list, gts_kdtree_range (node, bbox, compare));
-  }
-  return list;
-}
-
diff --git a/src/gts/matrix.c b/src/gts/matrix.c
deleted file mode 100644
index 7ada15d..0000000
--- a/src/gts/matrix.c
+++ /dev/null
@@ -1,725 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <math.h>
-#include "gts.h"
-
-/**
- * gts_matrix_new:
- * @a00: element [0][0].
- * @a01: element [0][1].
- * @a02: element [0][2].
- * @a03: element [0][3].
- * @a10: element [1][0].
- * @a11: element [1][1].
- * @a12: element [1][2].
- * @a13: element [1][3].
- * @a20: element [2][0].
- * @a21: element [2][1].
- * @a22: element [2][2].
- * @a23: element [2][3].
- * @a30: element [3][0].
- * @a31: element [3][1].
- * @a32: element [3][2].
- * @a33: element [3][3].
- *
- * Allocates memory and initializes a new #GtsMatrix.
- *
- * Returns: a pointer to the newly created #GtsMatrix.
- */
-GtsMatrix * gts_matrix_new (gdouble a00, gdouble a01, gdouble a02, gdouble a03,
-			    gdouble a10, gdouble a11, gdouble a12, gdouble a13,
-			    gdouble a20, gdouble a21, gdouble a22, gdouble a23,
-			    gdouble a30, gdouble a31, gdouble a32, gdouble a33)
-{
-  GtsMatrix * m;
-
-  m = g_malloc (4*sizeof (GtsVector4));
-
-  m[0][0] = a00; m[1][0] = a10; m[2][0] = a20; m[3][0] = a30;
-  m[0][1] = a01; m[1][1] = a11; m[2][1] = a21; m[3][1] = a31;
-  m[0][2] = a02; m[1][2] = a12; m[2][2] = a22; m[3][2] = a32;
-  m[0][3] = a03; m[1][3] = a13; m[2][3] = a23; m[3][3] = a33;
-
-  return m;
-}
-
-/**
- * gts_matrix_assign:
- * @m: a #GtsMatrix.
- * @a00: element [0][0].
- * @a01: element [0][1].
- * @a02: element [0][2].
- * @a03: element [0][3].
- * @a10: element [1][0].
- * @a11: element [1][1].
- * @a12: element [1][2].
- * @a13: element [1][3].
- * @a20: element [2][0].
- * @a21: element [2][1].
- * @a22: element [2][2].
- * @a23: element [2][3].
- * @a30: element [3][0].
- * @a31: element [3][1].
- * @a32: element [3][2].
- * @a33: element [3][3].
- *
- * Set values of matrix elements.
- */
-void gts_matrix_assign (GtsMatrix * m,
-			gdouble a00, gdouble a01, gdouble a02, gdouble a03,
-			gdouble a10, gdouble a11, gdouble a12, gdouble a13,
-			gdouble a20, gdouble a21, gdouble a22, gdouble a23,
-			gdouble a30, gdouble a31, gdouble a32, gdouble a33)
-{
-  g_return_if_fail (m != NULL);
-
-  m[0][0] = a00; m[1][0] = a10; m[2][0] = a20; m[3][0] = a30;
-  m[0][1] = a01; m[1][1] = a11; m[2][1] = a21; m[3][1] = a31;
-  m[0][2] = a02; m[1][2] = a12; m[2][2] = a22; m[3][2] = a32;
-  m[0][3] = a03; m[1][3] = a13; m[2][3] = a23; m[3][3] = a33;
-}
-
-/**
- * gts_matrix_projection:
- * @t: a #GtsTriangle.
- *
- * Creates a new #GtsMatrix representing the projection onto a plane of normal
- * given by @t.
- *
- * Returns: a pointer to the newly created #GtsMatrix.
- */
-GtsMatrix * gts_matrix_projection (GtsTriangle * t)
-{
-  GtsVertex * v1, * v2, * v3;
-  GtsEdge * e1, * e2, * e3;
-  GtsMatrix * m;
-  gdouble x1, y1, z1, x2, y2, z2, x3, y3, z3, l;
-  
-  g_return_val_if_fail (t != NULL, NULL);
-
-  m = g_malloc (4*sizeof (GtsVector4));
-  gts_triangle_vertices_edges (t, NULL, &v1, &v2, &v3, &e1, &e2, &e3);
-
-  x1 = GTS_POINT (v2)->x - GTS_POINT (v1)->x; 
-  y1 = GTS_POINT (v2)->y - GTS_POINT (v1)->y; 
-  z1 = GTS_POINT (v2)->z - GTS_POINT (v1)->z;
-  x2 = GTS_POINT (v3)->x - GTS_POINT (v1)->x; 
-  y2 = GTS_POINT (v3)->y - GTS_POINT (v1)->y; 
-  z2 = GTS_POINT (v3)->z - GTS_POINT (v1)->z;
-  x3 = y1*z2 - z1*y2; y3 = z1*x2 - x1*z2; z3 = x1*y2 - y1*x2;
-  x2 = y3*z1 - z3*y1; y2 = z3*x1 - x3*z1; z2 = x3*y1 - y3*x1;
-
-  g_assert ((l = sqrt (x1*x1 + y1*y1 + z1*z1)) > 0.0);
-  m[0][0] = x1/l; m[1][0] = y1/l; m[2][0] = z1/l; m[3][0] = 0.;
-  g_assert ((l = sqrt (x2*x2 + y2*y2 + z2*z2)) > 0.0);
-  m[0][1] = x2/l; m[1][1] = y2/l; m[2][1] = z2/l; m[3][1] = 0.;
-  g_assert ((l = sqrt (x3*x3 + y3*y3 + z3*z3)) > 0.0);
-  m[0][2] = x3/l; m[1][2] = y3/l; m[2][2] = z3/l; m[3][2] = 0.;
-  m[0][3] = 0; m[1][3] = 0.; m[2][3] = 0.; m[3][3] = 1.;
-
-  return m;
-}
-
-/**
- * gts_matrix_transpose:
- * @m: a #GtsMatrix.
- *
- * Returns: a pointer to a newly created #GtsMatrix transposed of @m.
- */
-GtsMatrix * gts_matrix_transpose (GtsMatrix * m)
-{
-  GtsMatrix * mi;
-
-  g_return_val_if_fail (m != NULL, NULL);
-
-  mi = g_malloc (4*sizeof (GtsVector4));
-
-  mi[0][0] = m[0][0]; mi[1][0] = m[0][1]; 
-  mi[2][0] = m[0][2]; mi[3][0] = m[0][3];
-  mi[0][1] = m[1][0]; mi[1][1] = m[1][1]; 
-  mi[2][1] = m[1][2]; mi[3][1] = m[1][3];
-  mi[0][2] = m[2][0]; mi[1][2] = m[2][1]; 
-  mi[2][2] = m[2][2]; mi[3][2] = m[2][3];
-  mi[0][3] = m[3][0]; mi[1][3] = m[3][1]; 
-  mi[2][3] = m[3][2]; mi[3][3] = m[3][3];
-
-  return mi;
-}
-
-/*
- * calculate the determinant of a 2x2 matrix.
- * 
- * Adapted from:
- * Matrix Inversion
- * by Richard Carling
- * from "Graphics Gems", Academic Press, 1990
- */
-static gdouble det2x2 (gdouble a, gdouble b, gdouble c, gdouble d)
-{
-  gdouble ans2;
-
-  ans2 = a*d - b*c;
-  return ans2;
-}
-
-/*
- * calculate the determinant of a 3x3 matrix
- * in the form
- *
- *     | a1,  b1,  c1 |
- *     | a2,  b2,  c2 |
- *     | a3,  b3,  c3 |
- *
- * Adapted from:
- * Matrix Inversion
- * by Richard Carling
- * from "Graphics Gems", Academic Press, 1990
- */
-static gdouble det3x3 (gdouble a1, gdouble a2, gdouble a3, 
-		       gdouble b1, gdouble b2, gdouble b3, 
-		       gdouble c1, gdouble c2, gdouble c3)
-{
-  gdouble ans3;
-
-  ans3 = a1 * det2x2( b2, b3, c2, c3 )
-    - b1 * det2x2( a2, a3, c2, c3 )
-    + c1 * det2x2( a2, a3, b2, b3 );
-  return ans3;
-}
-
-/**
- * gts_matrix_determinant:
- * @m: a #GtsMatrix.
- *
- * Returns: the value of det(@m).
- */
-gdouble gts_matrix_determinant (GtsMatrix * m)
-{
-  gdouble ans4;
-  gdouble a1, a2, a3, a4, b1, b2, b3, b4, c1, c2, c3, c4, d1, d2, d3, d4;
-
-  g_return_val_if_fail (m != NULL, 0.0);
-
-  a1 = m[0][0]; b1 = m[0][1]; 
-  c1 = m[0][2]; d1 = m[0][3];
-  
-  a2 = m[1][0]; b2 = m[1][1]; 
-  c2 = m[1][2]; d2 = m[1][3];
-  
-  a3 = m[2][0]; b3 = m[2][1]; 
-  c3 = m[2][2]; d3 = m[2][3];
-  
-  a4 = m[3][0]; b4 = m[3][1]; 
-  c4 = m[3][2]; d4 = m[3][3];
-  
-  ans4 = a1 * det3x3 (b2, b3, b4, c2, c3, c4, d2, d3, d4)
-    - b1 * det3x3 (a2, a3, a4, c2, c3, c4, d2, d3, d4)
-    + c1 * det3x3 (a2, a3, a4, b2, b3, b4, d2, d3, d4)
-    - d1 * det3x3 (a2, a3, a4, b2, b3, b4, c2, c3, c4);
-
-  return ans4;
-}
-
-/* 
- *   adjoint( original_matrix, inverse_matrix )
- * 
- *     calculate the adjoint of a 4x4 matrix
- *
- *      Let  a   denote the minor determinant of matrix A obtained by
- *           ij
- *
- *      deleting the ith row and jth column from A.
- *
- *                    i+j
- *     Let  b   = (-1)    a
- *          ij            ji
- *
- *    The matrix B = (b  ) is the adjoint of A
- *                     ij
- */
-static GtsMatrix * adjoint (GtsMatrix * m)
-{
-  gdouble a1, a2, a3, a4, b1, b2, b3, b4;
-  gdouble c1, c2, c3, c4, d1, d2, d3, d4;
-  GtsMatrix * ma;
-
-  a1 = m[0][0]; b1 = m[0][1]; 
-  c1 = m[0][2]; d1 = m[0][3];
-  
-  a2 = m[1][0]; b2 = m[1][1]; 
-  c2 = m[1][2]; d2 = m[1][3];
-  
-  a3 = m[2][0]; b3 = m[2][1];
-  c3 = m[2][2]; d3 = m[2][3];
-  
-  a4 = m[3][0]; b4 = m[3][1]; 
-  c4 = m[3][2]; d4 = m[3][3];
-
-  ma = g_malloc (4*sizeof (GtsVector4));
-
-  /* row column labeling reversed since we transpose rows & columns */
-
-  ma[0][0]  =   det3x3 (b2, b3, b4, c2, c3, c4, d2, d3, d4);
-  ma[1][0]  = - det3x3 (a2, a3, a4, c2, c3, c4, d2, d3, d4);
-  ma[2][0]  =   det3x3 (a2, a3, a4, b2, b3, b4, d2, d3, d4);
-  ma[3][0]  = - det3x3 (a2, a3, a4, b2, b3, b4, c2, c3, c4);
-  
-  ma[0][1]  = - det3x3 (b1, b3, b4, c1, c3, c4, d1, d3, d4);
-  ma[1][1]  =   det3x3 (a1, a3, a4, c1, c3, c4, d1, d3, d4);
-  ma[2][1]  = - det3x3 (a1, a3, a4, b1, b3, b4, d1, d3, d4);
-  ma[3][1]  =   det3x3 (a1, a3, a4, b1, b3, b4, c1, c3, c4);
-  
-  ma[0][2]  =   det3x3 (b1, b2, b4, c1, c2, c4, d1, d2, d4);
-  ma[1][2]  = - det3x3 (a1, a2, a4, c1, c2, c4, d1, d2, d4);
-  ma[2][2]  =   det3x3 (a1, a2, a4, b1, b2, b4, d1, d2, d4);
-  ma[3][2]  = - det3x3 (a1, a2, a4, b1, b2, b4, c1, c2, c4);
-  
-  ma[0][3]  = - det3x3 (b1, b2, b3, c1, c2, c3, d1, d2, d3);
-  ma[1][3]  =   det3x3 (a1, a2, a3, c1, c2, c3, d1, d2, d3);
-  ma[2][3]  = - det3x3 (a1, a2, a3, b1, b2, b3, d1, d2, d3);
-  ma[3][3]  =   det3x3 (a1, a2, a3, b1, b2, b3, c1, c2, c3);
-  
-  return ma;
-}
-
-
-/**
- * gts_matrix_inverse:
- * @m: a #GtsMatrix.
- *
- * Returns: a pointer to a newly created #GtsMatrix inverse of @m or %NULL
- * if @m is not invertible.
- */
-GtsMatrix * gts_matrix_inverse (GtsMatrix * m)
-{
-  GtsMatrix * madj;
-  gdouble det;
-  gint i, j;
-
-  g_return_val_if_fail (m != NULL, NULL);
-  
-  det = gts_matrix_determinant (m);
-  if (det == 0.)
-    return NULL;
-
-  madj = adjoint (m);
-  for (i = 0; i < 4; i++)
-    for(j = 0; j < 4; j++)
-      madj[i][j] /= det;
-
-  return madj;
-}
-
-/**
- * gts_matrix3_inverse:
- * @m: a 3x3 #GtsMatrix.
- *
- * Returns: a pointer to a newly created 3x3 #GtsMatrix inverse of @m or %NULL
- * if @m is not invertible.
- */
-GtsMatrix * gts_matrix3_inverse (GtsMatrix * m)
-{
-  GtsMatrix * mi;
-  gdouble det;
-
-  g_return_val_if_fail (m != NULL, NULL);
-  
-  det = (m[0][0]*(m[1][1]*m[2][2] - m[2][1]*m[1][2]) - 
-	 m[0][1]*(m[1][0]*m[2][2] - m[2][0]*m[1][2]) + 
-	 m[0][2]*(m[1][0]*m[2][1] - m[2][0]*m[1][1]));
-  if (det == 0.0)
-    return NULL;
-
-  mi = g_malloc0 (4*sizeof (GtsVector));
-
-  mi[0][0] = (m[1][1]*m[2][2] - m[1][2]*m[2][1])/det; 
-  mi[0][1] = (m[2][1]*m[0][2] - m[0][1]*m[2][2])/det;
-  mi[0][2] = (m[0][1]*m[1][2] - m[1][1]*m[0][2])/det; 
-  mi[1][0] = (m[1][2]*m[2][0] - m[1][0]*m[2][2])/det; 
-  mi[1][1] = (m[0][0]*m[2][2] - m[2][0]*m[0][2])/det; 
-  mi[1][2] = (m[1][0]*m[0][2] - m[0][0]*m[1][2])/det; 
-  mi[2][0] = (m[1][0]*m[2][1] - m[2][0]*m[1][1])/det; 
-  mi[2][1] = (m[2][0]*m[0][1] - m[0][0]*m[2][1])/det; 
-  mi[2][2] = (m[0][0]*m[1][1] - m[0][1]*m[1][0])/det; 
-
-  return mi;
-}
-
-/**
- * gts_matrix_print:
- * @m: a #GtsMatrix.
- * @fptr: a file descriptor.
- * 
- * Print @m to file @fptr.
- */
-void gts_matrix_print (GtsMatrix * m, FILE * fptr)
-{
-  g_return_if_fail (m != NULL);
-  g_return_if_fail (fptr != NULL);
-
-  fprintf (fptr, 
-	   "[[%15.7g %15.7g %15.7g %15.7g]\n"
-	   " [%15.7g %15.7g %15.7g %15.7g]\n"
-	   " [%15.7g %15.7g %15.7g %15.7g]\n"
-	   " [%15.7g %15.7g %15.7g %15.7g]]\n",
-	   m[0][0], m[0][1], m[0][2], m[0][3],
-	   m[1][0], m[1][1], m[1][2], m[1][3],
-	   m[2][0], m[2][1], m[2][2], m[2][3],
-	   m[3][0], m[3][1], m[3][2], m[3][3]);
-}
-
-/**
- * gts_vector_print:
- * @v: a #GtsVector.
- * @fptr: a file descriptor.
- * 
- * Print @s to file @fptr.
- */
-void gts_vector_print (GtsVector v, FILE * fptr)
-{
-  g_return_if_fail (fptr != NULL);
-
-  fprintf (fptr, 
-	   "[%15.7g %15.7g %15.7g ]\n",
-	   v[0], v[1], v[2]);
-}
-
-/**
- * gts_vector4_print:
- * @v: a #GtsVector4.
- * @fptr: a file descriptor.
- * 
- * Print @v to file @fptr.
- */
-void gts_vector4_print (GtsVector4 v, FILE * fptr)
-{
-  g_return_if_fail (fptr != NULL);
-
-  fprintf (fptr, 
-	   "[%15.7g %15.7g %15.7g %15.7g]\n",
-	   v[0], v[1], v[2], v[3]);
-}
-
-/* [cos(alpha)]^2 */
-#define COSALPHA2 0.999695413509 /* alpha = 1 degree */
-/* [sin(alpha)]^2 */
-#define SINALPHA2 3.04586490453e-4 /* alpha = 1 degree */
-
-/**
- * gts_matrix_compatible_row:
- * @A: a #GtsMatrix.
- * @b: a #GtsVector.
- * @n: the number of previous constraints of @A.x=@b.
- * @A1: a #GtsMatrix.
- * @b1: a #GtsVector.
- *
- * Given a system of @n constraints @A.x=@b adds to it the compatible
- * constraints defined by @A1.x=@b1. The compatibility is determined
- * by insuring that the resulting system is well-conditioned (see
- * Lindstrom and Turk (1998, 1999)).
- *
- * Returns: the number of constraints of the resulting system.  
- */
-guint gts_matrix_compatible_row (GtsMatrix * A,
-				 GtsVector b,
-				 guint n,
-				 GtsVector A1,
-				 gdouble b1)
-{
-  gdouble na1;
-  
-  g_return_val_if_fail (A != NULL, 0);
-
-  na1 = gts_vector_scalar (A1, A1);
-  if (na1 == 0.0)
-    return n;
-
-  /* normalize row */
-  na1 = sqrt (na1);
-  A1[0] /= na1; A1[1] /= na1; A1[2] /= na1; b1 /= na1;
-
-  if (n == 1) {
-    gdouble a0a1 = gts_vector_scalar (A[0], A1);
-    if (a0a1*a0a1 >= COSALPHA2)
-      return 1;
-  }
-  else if (n == 2) {
-    GtsVector V;
-    gdouble s;
-    
-    gts_vector_cross (V, A[0], A[1]);
-    s = gts_vector_scalar (V, A1);
-    if (s*s <= gts_vector_scalar (V, V)*SINALPHA2)
-      return 2;
-  }
-
-  A[n][0] = A1[0]; A[n][1] = A1[1]; A[n][2] = A1[2]; b[n] = b1;
-  return n + 1;
-}
-
-/**
- * gts_matrix_quadratic_optimization:
- * @A: a #GtsMatrix.
- * @b: a #GtsVector.
- * @n: the number of constraints (must be smaller than 3).
- * @H: a symmetric positive definite Hessian.
- * @c: a #GtsVector.
- *
- * Solve a quadratic optimization problem: Given a quadratic objective function
- * f which can be written as: f(x) = x^t.@xxx + @c^t.x + k, where @H is the 
- * symmetric positive definite Hessian of f and k is a constant, find the
- * minimum of f subject to the set of @n prior linear constraints, defined by
- * the first @n rows of @A and @b (@A.x = @b). The new constraints given by
- * the minimization are added to @A and @b only if they are linearly
- * independent as determined by gts_matrix_compatible_row().
- *
- * Returns: the new number of constraints defined by @A and @b.
- */
-guint gts_matrix_quadratic_optimization (GtsMatrix * A,
-					 GtsVector b,
-					 guint n,
-					 GtsMatrix * H,
-					 GtsVector c)
-{
-  g_return_val_if_fail (A != NULL, 0);
-  g_return_val_if_fail (b != NULL, 0);
-  g_return_val_if_fail (n < 3, 0);
-  g_return_val_if_fail (H != NULL, 0);
-
-  switch (n) {
-  case 0: {
-    n = gts_matrix_compatible_row (A, b, n, H[0], - c[0]);
-    n = gts_matrix_compatible_row (A, b, n, H[1], - c[1]);
-    n = gts_matrix_compatible_row (A, b, n, H[2], - c[2]);
-    return n;
-  }
-  case 1: {
-    GtsVector Q0 = {0., 0., 0.};
-    GtsVector Q1 = {0., 0., 0.};
-    GtsVector A1;
-    gdouble max = A[0][0]*A[0][0];
-    guint d = 0;
-
-    /* build a vector orthogonal to the constraint */
-    if (A[0][1]*A[0][1] > max) { max = A[0][1]*A[0][1]; d = 1; }
-    if (A[0][2]*A[0][2] > max) { max = A[0][2]*A[0][2]; d = 2; }
-    switch (d) {
-    case 0: Q0[0] = - A[0][2]/A[0][0]; Q0[2] = 1.0; break;
-    case 1: Q0[1] = - A[0][2]/A[0][1]; Q0[2] = 1.0; break;
-    case 2: Q0[2] = - A[0][0]/A[0][2]; Q0[0] = 1.0; break;
-    }
-
-    /* build a second vector orthogonal to the first and to the constraint */
-    gts_vector_cross (Q1, A[0], Q0);
-
-    A1[0] = gts_vector_scalar (Q0, H[0]);
-    A1[1] = gts_vector_scalar (Q0, H[1]);
-    A1[2] = gts_vector_scalar (Q0, H[2]);
-
-    n = gts_matrix_compatible_row (A, b, n, A1, - gts_vector_scalar (Q0, c));
-    
-    A1[0] = gts_vector_scalar (Q1, H[0]);
-    A1[1] = gts_vector_scalar (Q1, H[1]);
-    A1[2] = gts_vector_scalar (Q1, H[2]);
-
-    n = gts_matrix_compatible_row (A, b, n, A1, - gts_vector_scalar (Q1, c));
-
-    return n;
-  }
-  case 2: {
-    /* build a vector orthogonal to the two constraints */
-    GtsVector A1, Q;
-
-    gts_vector_cross (Q, A[0], A[1]);
-    A1[0] = gts_vector_scalar (Q, H[0]);
-    A1[1] = gts_vector_scalar (Q, H[1]);
-    A1[2] = gts_vector_scalar (Q, H[2]);
-    
-    n = gts_matrix_compatible_row (A, b, n, A1, - gts_vector_scalar (Q, c));
-
-    return n;
-  }
-  default:
-    g_assert_not_reached ();
-  }
-  return 0;
-}
-
-/**
- * gts_matrix_destroy:
- * @m: a #GtsMatrix.
- *
- * Free all the memory allocated for @m.
- */
-void gts_matrix_destroy (GtsMatrix * m)
-{
-  g_free (m);
-}
-
-/**
- * gts_matrix_product:
- * @m1: a #GtsMatrix.
- * @m2: another #GtsMatrix.
- *
- * Returns: a new #GtsMatrix, product of @m1 and @m2.
- */
-GtsMatrix * gts_matrix_product (GtsMatrix * m1, GtsMatrix * m2)
-{
-  guint i, j;
-  GtsMatrix * m;
-
-  g_return_val_if_fail (m1 != NULL, NULL);
-  g_return_val_if_fail (m2 != NULL, NULL);
-  g_return_val_if_fail (m1 != m2, NULL);
-
-  m = g_malloc (4*sizeof (GtsVector4));
-
-  for (i = 0; i < 4; i++)
-    for (j = 0; j < 4; j++)
-      m[i][j] = m1[i][0]*m2[0][j] + m1[i][1]*m2[1][j] +
-        m1[i][2]*m2[2][j] + m1[i][3]*m2[3][j];
-  return m;
-}
-
-/**
- * gts_matrix_zero:
- * @m: a #GtsMatrix or $NULL.
- *
- * Initializes @m to zeros. Allocates a matrix if @m is %NULL.
- *
- * Returns: the zero'ed matrix.
- */
-GtsMatrix * gts_matrix_zero (GtsMatrix * m)
-{
-  if (m == NULL)
-    m = g_malloc0 (4*sizeof (GtsVector4));
-  else {
-    m[0][0] = m[1][0] = m[2][0] = m[3][0] = 0.;
-    m[0][1] = m[1][1] = m[2][1] = m[3][1] = 0.;
-    m[0][2] = m[1][2] = m[2][2] = m[3][2] = 0.;
-    m[0][3] = m[1][3] = m[2][3] = m[3][3] = 0.;
-  }
-  return m;
-}
-
-/**
- * gts_matrix_identity:
- * @m: a #GtsMatrix or %NULL.
- *
- * Initializes @m to an identity matrix. Allocates a matrix if @m is %NULL.
- *
- * Returns: the identity matrix.
- */
-GtsMatrix * gts_matrix_identity (GtsMatrix * m)
-{
-  m = gts_matrix_zero (m);
-  m[0][0] = m[1][1] = m[2][2] = m[3][3] = 1.;
-  return m;
-}
-
-/**
- * gts_matrix_scale:
- * @m: a #GtsMatrix or %NULL.
- * @s: the scaling vector.
- *
- * Initializes @m to a scaling matrix for @s. Allocates a matrix if @m
- * is %NULL.
- *
- * Returns: the scaling matrix.
- */
-GtsMatrix * gts_matrix_scale (GtsMatrix * m, GtsVector s)
-{
-  m = gts_matrix_zero (m);
-  m[0][0] = s[0];
-  m[1][1] = s[1];
-  m[2][2] = s[2];
-  m[3][3] = 1.;
-  return m;
-}
-
-/**
- * gts_matrix_translate:
- * @m: a #GtsMatrix or %NULL.
- * @t: the translation vector.
- *
- * Initializes @m to a translation matrix for @t.  Allocates a new
- * matrix if @m is %NULL.
- *
- * Returns: the translation matix.
- */
-GtsMatrix * gts_matrix_translate (GtsMatrix * m, GtsVector t)
-{
-  m = gts_matrix_zero (m);
-  m[0][3] = t[0];
-  m[1][3] = t[1];
-  m[2][3] = t[2];
-  m[3][3] = 1.;
-  m[0][0] = m[1][1] = m[2][2] = 1.;
-  return m;
-}
-
-/**
- * gts_matrix_rotate:
- * @m: a #GtsMatrix or %NULL.
- * @r: the rotation axis.
- * @angle: the angle (in radians) to rotate by.
- *
- * Initializes @m to a rotation matrix around @r by @angle.
- * Allocates a new matrix if @m is %NULL.
- *
- * Returns: the rotation matrix.
- */
-GtsMatrix * gts_matrix_rotate (GtsMatrix * m,
-			       GtsVector r,
-			       gdouble angle)
-{
-  gdouble c, c1, s;
-
-  gts_vector_normalize (r);
-
-  c = cos (angle);
-  c1 = 1. - c;
-  s = sin (angle);
-
-  if (m == NULL)
-    m = g_malloc (4*sizeof (GtsVector4));
-
-  m[0][0] = r[0]*r[0]*c1 + c;
-  m[0][1] = r[0]*r[1]*c1 - r[2]*s;
-  m[0][2] = r[0]*r[2]*c1 + r[1]*s;
-  m[0][3] = 0.;
-
-  m[1][0] = r[1]*r[0]*c1 + r[2]*s;
-  m[1][1] = r[1]*r[1]*c1 + c;
-  m[1][2] = r[1]*r[2]*c1 - r[0]*s;
-  m[1][3] = 0.;
-
-  m[2][0] = r[2]*r[0]*c1 - r[1]*s;
-  m[2][1] = r[2]*r[1]*c1 + r[0]*s;
-  m[2][2] = r[2]*r[2]*c1 + c;
-  m[2][3] = 0.;
-
-  m[3][0] = 0.;
-  m[3][1] = 0.;
-  m[3][2] = 0.;
-  m[3][3] = 1.;
-
-  return m;
-}
diff --git a/src/gts/misc.c b/src/gts/misc.c
deleted file mode 100644
index 393ba06..0000000
--- a/src/gts/misc.c
+++ /dev/null
@@ -1,692 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <stdlib.h>
-#include <string.h>
-
-#include "gts.h"
-#include "gts-private.h"
-#include "config.h"
-
-const guint gts_major_version = GTS_MAJOR_VERSION;
-const guint gts_minor_version = GTS_MINOR_VERSION;
-const guint gts_micro_version = GTS_MICRO_VERSION;
-const guint gts_interface_age = 1;
-const guint gts_binary_age = 1;
-
-static gboolean char_in_string (char c, const char * s)
-{
-  while (*s != '\0')
-    if (*(s++) == c)
-      return TRUE;
-  return FALSE;
-}
-
-static GtsFile * file_new (void)
-{
-  GtsFile * f;
-
-  f = g_malloc (sizeof (GtsFile));
-  f->fp = NULL;
-  f->s = f->s1 = NULL;
-  f->curline = 1;
-  f->curpos = 1;
-  f->token = g_string_new ("");
-  f->type = '\0';
-  f->error = NULL;
-  f->next_token = '\0';
-
-  f->scope = f->scope_max = 0;
-  f->delimiters = g_strdup (" \t");
-  f->comments = g_strdup (GTS_COMMENTS);
-  f->tokens = g_strdup ("\n{}()=");
-
-  return f;
-}
-
-/**
- * gts_file_new:
- * @fp: a file pointer.
- *
- * Returns: a new #GtsFile.
- */
-GtsFile * gts_file_new (FILE * fp)
-{
-  GtsFile * f;
-
-  g_return_val_if_fail (fp != NULL, NULL);
-
-  f = file_new ();
-  f->fp = fp;
-  gts_file_next_token (f);
-
-  return f;
-}
-
-/**
- * gts_file_new_from_string:
- * @s: a string.
- *
- * Returns: a new #GtsFile.
- */
-GtsFile * gts_file_new_from_string (const gchar * s)
-{
-  GtsFile * f;
-
-  g_return_val_if_fail (s != NULL, NULL);
-
-  f = file_new ();
-  f->s1 = f->s = g_strdup (s);
-  gts_file_next_token (f);
-
-  return f;
-}
-
-/**
- * gts_file_destroy:
- * @f: a #GtsFile.
- *
- * Frees all the memory allocated for @f.
- */
-void gts_file_destroy (GtsFile * f)
-{
-  g_return_if_fail (f != NULL);
-
-  g_free (f->delimiters);
-  g_free (f->comments);
-  g_free (f->tokens);
-  if (f->error)
-    g_free (f->error);
-  if (f->s1)
-    g_free (f->s1);
-  g_string_free (f->token, TRUE);
-  g_free (f);
-}
-
-/**
- * gts_file_verror:
- * @f: a @GtsFile.
- * @format: the standard sprintf() format string.
- * @args: the list of parameters to insert into the format string.
- *
- * Sets the @error field of @f using g_strdup_vprintf().
- *
- * This function can be called only once and disables any other
- * operation on @f (gts_file_close() excepted).
- */
-void gts_file_verror (GtsFile * f,
-		      const gchar * format,
-		      va_list args)
-{
-  g_return_if_fail (f != NULL);
-  g_return_if_fail (format != NULL);
-
-  g_assert (f->type != GTS_ERROR);
-  f->error = g_strdup_vprintf (format, args);
-  f->type = GTS_ERROR;
-}
-
-/**
- * gts_file_error:
- * @f: a @GtsFile.
- * @format: the standard sprintf() format string.
- * @...: the parameters to insert into the format string.
- *
- * Sets the @error field of @f using gts_file_verror().
- *
- * This function can be called only once and disables any other
- * operation on @f (gts_file_close() excepted).
- */
-void gts_file_error (GtsFile * f,
-		     const gchar * format,
-		     ...)
-{
-  va_list args;
-
-  g_return_if_fail (f != NULL);
-  g_return_if_fail (format != NULL);
-
-  va_start (args, format);  
-  gts_file_verror (f, format, args);
-  va_end (args);
-}
-
-static gint next_char (GtsFile * f)
-{
-  if (f->fp)
-    return fgetc (f->fp);
-  else if (*f->s == '\0')
-    return EOF;
-  return *(f->s++);
-}
-
-/**
- * gts_file_getc :
- * @f: a #GtsFile.
- *
- * Returns: the next character in @f or EOF if the end of the file is
- * reached or if an error occured.
- */
-gint gts_file_getc (GtsFile * f)
-{
-  gint c;
-
-  g_return_val_if_fail (f != NULL, EOF);
-
-  if (f->type == GTS_ERROR)
-    return EOF;
-
-  c = next_char (f);
-  f->curpos++;
-  while (char_in_string (c, f->comments)) {
-    while (c != EOF && c != '\n')
-      c = next_char (f);
-    if (c == '\n') {
-      f->curline++;
-      f->curpos = 1;
-      c = next_char (f);
-    }
-  }
-  switch (c) {
-  case '\n': 
-    f->curline++;
-    f->curpos = 1; 
-    break;
-  case '{':
-    f->scope++; 
-    break;
-  case '}':
-    if (f->scope == 0) {
-      f->line = f->curline;
-      f->pos = f->curpos - 1;
-      gts_file_error (f, "no matching opening brace");
-      c = EOF;
-    }
-    else
-      f->scope--;
-  }
-  return c;
-}
-
-/**
- * gts_file_read:
- * @f: a #GtsFile.
- * @ptr: a pointer.
- * @size: size of an element.
- * @nmemb: number of elements.
- *
- * Reads @nmemb elements of data, each @size bytes long, from @f,
- * storing them at the location given by @ptr.
- *
- * Returns: the number of elements read.
- */
-guint gts_file_read (GtsFile * f, gpointer ptr, guint size, guint nmemb)
-{
-  guint i, n;
-  gchar * p;
-
-  g_return_val_if_fail (f != NULL, 0);
-  g_return_val_if_fail (ptr != NULL, 0);
-  g_return_val_if_fail (f->fp != NULL, 0);
-
-  if (f->type == GTS_ERROR)
-    return 0;
-
-  n = fread (ptr, size, nmemb, f->fp);
-  for (i = 0, p = ptr; i < n*size; i++, p++) {
-    f->curpos++;
-    if (*p == '\n') {
-      f->curline++;
-      f->curpos = 1;
-    }
-  }
-  return n;
-}
-
-/**
- * gts_file_getc_scope :
- * @f: a #GtsFile.
- *
- * Returns: the next character in @f in the scope defined by
- * @f->scope_max or EOF if the end of the file is reached or if an
- * error occured.
- */
-gint gts_file_getc_scope (GtsFile * f)
-{
-  gint c;
-
-  g_return_val_if_fail (f != NULL, EOF);
-
-  if (f->type == GTS_ERROR)
-    return EOF;
-  
-  if (f->scope <= f->scope_max)
-    c = gts_file_getc (f);
-  else {
-    c = gts_file_getc (f);
-    while (c != EOF && f->scope > f->scope_max)
-      c = gts_file_getc (f);    
-  }
-  return c;
-}
-
-/**
- * gts_file_next_token:
- * @f: a #GtsFile.
- *
- * Reads next token from @f and updates its @token and @delim fields.
- */
-void gts_file_next_token (GtsFile * f)
-{
-  gint c;
-  gboolean in_string = FALSE;
-
-  g_return_if_fail (f != NULL);
-
-  if (f->type == GTS_ERROR)
-    return;
-  f->token->str[0] = '\0';
-  f->token->len = 0;
-  if (f->next_token != '\0') {
-    if (char_in_string (f->next_token, f->tokens)) {
-      f->line = f->curline;
-      f->pos = f->curpos - 1;
-      g_string_append_c (f->token, f->next_token);
-      f->type = f->next_token;
-      f->next_token = '\0';
-      return;
-    }
-    else {
-      c = f->next_token;
-      f->next_token = '\0';
-    }
-  }
-  else
-    c = gts_file_getc_scope (f);
-  f->type = GTS_NONE;
-  while (c != EOF && (!in_string || !char_in_string (c, f->delimiters))) {
-    if (in_string) {
-      if (char_in_string (c, f->tokens)) {
-	f->next_token = c;
-	break;
-      }
-      g_string_append_c (f->token, c);
-    }
-    else if (!char_in_string (c, f->delimiters)) {
-      in_string = TRUE;
-      f->line = f->curline;
-      f->pos = f->curpos - 1;
-      g_string_append_c (f->token, c);
-      if (char_in_string (c, f->tokens)) {
-	f->type = c;
-	break;
-      }
-    }
-    c = gts_file_getc_scope (f);
-  }
-  if (f->type == GTS_NONE && f->token->len > 0) {
-    gchar * a;
-
-    a = f->token->str;
-    while (*a != '\0' && char_in_string (*a, "+-")) a++;
-    if (*a == '\0') {
-      f->type = GTS_STRING;
-      return;
-    }
-    a = f->token->str;
-    while (*a != '\0' && char_in_string (*a, "+-0123456789")) a++;
-    if (*a == '\0') {
-      f->type = GTS_INT;
-      return;
-    }
-    a = f->token->str;
-    while (*a != '\0' && char_in_string (*a, "+-eE.")) a++;
-    if (*a == '\0') {
-      f->type = GTS_STRING;
-      return;
-    }
-    a = f->token->str;
-    while (*a != '\0' && char_in_string (*a, "+-0123456789eE.")) a++;
-    if (*a == '\0') {
-      f->type = GTS_FLOAT;
-      return;
-    }
-    a = f->token->str;
-    if (!strncmp (a, "0x", 2) || 
-	!strncmp (a, "-0x", 3) || 
-	!strncmp (a, "+0x", 3)) {
-      while (*a != '\0' && char_in_string (*a, "+-0123456789abcdefx")) a++;
-      if (*a == '\0') {
-	f->type = GTS_INT;
-	return;
-      }
-      a = f->token->str;
-      while (*a != '\0' && char_in_string (*a, "+-0123456789abcdefx.p")) a++;
-      if (*a == '\0') {
-	f->type = GTS_FLOAT;
-	return;
-      }
-    }
-    f->type = GTS_STRING;
-  }
-}
-
-/**
- * gts_file_first_token_after:
- * @f: a #GtsFile.
- * @type: a #GtsTokenType.
- *
- * Finds and sets the first token of a type different from @type 
- * occuring after a token of type @type.
- */
-void gts_file_first_token_after (GtsFile * f, GtsTokenType type)
-{
-  g_return_if_fail (f != NULL);
-
-  while (f->type != GTS_ERROR && 
-	 f->type != GTS_NONE &&
-	 f->type != type)
-    gts_file_next_token (f);
-  while (f->type == type)
-    gts_file_next_token (f);
-}
-
-/**
- * gts_file_assign_start:
- * @f: a #GtsFile.
- * @vars: a %GTS_NONE terminated array of #GtsFileVariable.
- *
- * Opens a block delimited by braces to read a list of optional
- * arguments specified by @vars.  
- *
- * If an error is encountered the @error field of @f is set.
- */
-void gts_file_assign_start (GtsFile * f, GtsFileVariable * vars)
-{
-  GtsFileVariable * var;
-
-  g_return_if_fail (f != NULL);
-  g_return_if_fail (vars != NULL);
-
-  var = vars;
-  while (var->type != GTS_NONE)
-    (var++)->set = FALSE;
-
-  if (f->type != '{') {
-    gts_file_error (f, "expecting an opening brace");
-    return;
-  }
-
-  f->scope_max++;
-  gts_file_next_token (f);
-}
-
-/**
- * gts_file_assign_next:
- * @f: a #GtsFile.
- * @vars: a %GTS_NONE terminated array of #GtsFileVariable.
- *
- * Assigns the next optional argument of @vars read from @f.
- *
- * Returns: the variable of @vars which has been assigned or %NULL if
- * no variable has been assigned (if an error has been encountered the
- * @error field of @f is set).  
- */
-GtsFileVariable * gts_file_assign_next (GtsFile * f, GtsFileVariable * vars)
-{
-  GtsFileVariable * var;
-  gboolean found = FALSE;
-
-  g_return_val_if_fail (f != NULL, NULL);
-  g_return_val_if_fail (vars != NULL, NULL);
-
-  while (f->type == '\n')
-    gts_file_next_token (f);
-  if (f->type == '}') {
-    f->scope_max--;
-    gts_file_next_token (f);
-    return NULL;
-  }
-  if (f->type == GTS_ERROR)
-    return NULL;
-
-  var = vars;
-  while (f->type != GTS_ERROR && var->type != GTS_NONE && !found) {
-    if (!strcmp (var->name, f->token->str)) {
-      found = TRUE;
-      if (var->unique && var->set)
-	gts_file_error (f, "variable `%s' was already set at line %d:%d", 
-			var->name, var->line, var->pos);
-      else {
-	var->line = f->line;
-	var->pos = f->pos;
-	gts_file_next_token (f);
-	if (f->type != '=')
-	  gts_file_error (f, "expecting `='");
-	else {
-	  var->set = TRUE;
-	  switch (var->type) {
-	  case GTS_FILE:
-	    break;
-	  case GTS_INT:
-	    gts_file_next_token (f);
-	    if (f->type != GTS_INT) {
-	      gts_file_error (f, "expecting an integer");
-	      var->set = FALSE;
-	    }
-	    else if (var->data)
-	      *((gint *) var->data) = atoi (f->token->str); 
-	    break;
-	  case GTS_UINT:
-	    gts_file_next_token (f);
-	    if (f->type != GTS_INT) {
-	      gts_file_error (f, "expecting an integer");
-	      var->set = FALSE;
-	    }
-	    else if (var->data)
-	      *((guint *) var->data) = atoi (f->token->str); 
-	    break;
-	  case GTS_FLOAT:
-	    gts_file_next_token (f);
-	    if (f->type != GTS_INT && f->type != GTS_FLOAT) {
-	      gts_file_error (f, "expecting a number");
-	      var->set = FALSE;
-	    }
-	    else if (var->data)
-	      *((gfloat *) var->data) = atof (f->token->str); 
-	    break;
-	  case GTS_DOUBLE:
-	    gts_file_next_token (f);
-	    if (f->type != GTS_INT && f->type != GTS_FLOAT) {
-	      gts_file_error (f, "expecting a number");
-	      var->set = FALSE;
-	    }
-	    else if (var->data)
-	      *((gdouble *) var->data) = atof (f->token->str); 
-	    break;
-	  case GTS_STRING:
-	    gts_file_next_token (f);
-	    if (f->type != GTS_INT && 
-		f->type != GTS_FLOAT && 
-		f->type != GTS_STRING) {
-	      gts_file_error (f, "expecting a string");
-	      var->set = FALSE;
-	    }
-	    else if (var->data)
-	      *((gchar **) var->data) = g_strdup (f->token->str); 
-	    break;
-	  default:
-	    g_assert_not_reached ();
-	  }
-	}
-      }
-    }
-    else
-      var++;
-  }
-  if (!found)
-    gts_file_error (f, "unknown identifier `%s'", f->token->str);
-  else if (f->type != GTS_ERROR) {
-    g_assert (var->set);
-    gts_file_next_token (f);
-    return var;
-  }
-  return NULL;
-}
-
-/**
- * gts_file_assign_variables:
- * @f: a #GtsFile.
- * @vars: an array of #GtsFileVariable.
- *
- * Assigns all the variables belonging to @vars found in @f.
- *
- * If an error is encountered the @error field of @f is set.
- */
-void gts_file_assign_variables (GtsFile * f, GtsFileVariable * vars)
-{
-  g_return_if_fail (f != NULL);
-  g_return_if_fail (vars != NULL);
-
-  gts_file_assign_start (f, vars);
-  while (gts_file_assign_next (f, vars))
-    ;
-}
-
-/**
- * gts_file_variable_error:
- * @f: a #GtsFile.
- * @vars: an array of #GtsFileVariable.
- * @name: the name of a variable in @vars.
- * @format: the standard sprintf() format string.
- * @...: the parameters to insert into the format string.
- *
- * Sets the @error field of @f using gts_file_verror().
- *
- * String @name must match one of the variable names in @vars.
- *
- * If variable @name has been assigned (using gts_file_assign_variables())
- * sets the @line and @pos fields of @f to the line and position where
- * it has been assigned.
- */
-void gts_file_variable_error (GtsFile * f, 
-			      GtsFileVariable * vars,
-			      const gchar * name,
-			      const gchar * format,
-			      ...)
-{
-  va_list args;
-  GtsFileVariable * var;
-
-  g_return_if_fail (f != NULL);
-  g_return_if_fail (vars != NULL);
-  g_return_if_fail (name != NULL);
-  g_return_if_fail (format != NULL);
-
-  var = vars;
-  while (var->type != GTS_NONE && strcmp (var->name, name))
-    var++;
-
-  g_return_if_fail (var->type != GTS_NONE); /* @name not found in @vars */
-
-  if (var->set) {
-    f->line = var->line;
-    f->pos = var->pos;
-  }
-
-  va_start (args, format);  
-  gts_file_verror (f, format, args);
-  va_end (args);
-}
-
-#ifdef DEBUG_FUNCTIONS
-static GHashTable * ids = NULL;
-static guint next_id = 1;
-
-guint id (gpointer p)
-{
-  g_return_val_if_fail (p != NULL, 0);
-  g_return_val_if_fail (ids != NULL, 0);
-  g_assert (g_hash_table_lookup (ids, p));
-  return GPOINTER_TO_UINT (g_hash_table_lookup (ids, p));
-}
-
-void id_insert (gpointer p)
-{
-  g_return_if_fail (p != NULL);
-  if (ids == NULL) ids = g_hash_table_new (NULL, NULL);
-  g_assert (g_hash_table_lookup (ids, p) == NULL);
-  g_hash_table_insert (ids, p, GUINT_TO_POINTER (next_id++));
-}
-
-void id_remove (gpointer p)
-{
-  g_assert (g_hash_table_lookup (ids, p));  
-  g_hash_table_remove (ids, p);
-}
-
-void gts_write_triangle (GtsTriangle * t, 
-			 GtsPoint * o,
-			 FILE * fptr)
-{
-  gdouble xo = o ? o->x : 0.0;
-  gdouble yo = o ? o->y : 0.0;
-  gdouble zo = o ? o->z : 0.0;
-
-  g_return_if_fail (t != NULL && fptr != NULL);
-
-  fprintf (fptr, "(hdefine geometry \"t%d\" { =\n", id (t));
-  fprintf (fptr, "OFF 3 1 0\n"
-	   "%g %g %g\n%g %g %g\n%g %g %g\n3 0 1 2\n})\n"
-	   "(geometry \"t%d\" { : \"t%d\"})\n"
-	   "(normalization \"t%d\" none)\n",
-	   GTS_POINT (GTS_SEGMENT (t->e1)->v1)->x - xo, 
-	   GTS_POINT (GTS_SEGMENT (t->e1)->v1)->y - yo,
-	   GTS_POINT (GTS_SEGMENT (t->e1)->v1)->z - zo,
-	   GTS_POINT (GTS_SEGMENT (t->e1)->v2)->x - xo, 
-	   GTS_POINT (GTS_SEGMENT (t->e1)->v2)->y - yo, 
-	   GTS_POINT (GTS_SEGMENT (t->e1)->v2)->z - zo,
-	   GTS_POINT (gts_triangle_vertex (t))->x - xo,
-	   GTS_POINT (gts_triangle_vertex (t))->y - yo,
-	   GTS_POINT (gts_triangle_vertex (t))->z - zo,
-	   id (t), id (t), id (t));
-}
-
-void gts_write_segment (GtsSegment * s, 
-			GtsPoint * o,
-			FILE * fptr)
-{
-  gdouble xo = o ? o->x : 0.0;
-  gdouble yo = o ? o->y : 0.0;
-  gdouble zo = o ? o->z : 0.0;
-
-  g_return_if_fail (s != NULL && fptr != NULL);
-
-  fprintf (fptr, "(geometry \"s%d\" { =\n", id (s));
-  fprintf (fptr, "VECT 1 2 0 2 0 %g %g %g %g %g %g })\n"
-	   "(normalization \"s%d\" none)\n",
-	   GTS_POINT (s->v1)->x - xo, 
-	   GTS_POINT (s->v1)->y - yo, 
-	   GTS_POINT (s->v1)->z - zo,
-	   GTS_POINT (s->v2)->x - xo, 
-	   GTS_POINT (s->v2)->y - yo, 
-	   GTS_POINT (s->v2)->z - zo,
-	   id (s));
-}
-#endif /* DEBUG_FUNCTIONS */
diff --git a/src/gts/named.c b/src/gts/named.c
deleted file mode 100644
index 379f9f6..0000000
--- a/src/gts/named.c
+++ /dev/null
@@ -1,188 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <string.h>
-#include "gts.h"
-
-static void nvertex_read (GtsObject ** po, GtsFile * fp)
-{
-  if ((*po)->klass->parent_class->read)
-    (* (*po)->klass->parent_class->read) (po, fp);
-
-  if (fp->type != '\n' && fp->type != GTS_ERROR) {
-    strncpy (GTS_NVERTEX (*po)->name, fp->token->str, GTS_NAME_LENGTH);
-    gts_file_next_token (fp);
-  }
-}
-
-static void nvertex_write (GtsObject * o, FILE * fptr)
-{
-  GtsNVertex * nv = GTS_NVERTEX (o);
-
-  (* o->klass->parent_class->write) (o, fptr);
-  if (nv->name[0] != '\0')
-    fprintf (fptr, " %s", nv->name);
-}
-
-static void nvertex_class_init (GtsNVertexClass * klass)
-{
-  GTS_OBJECT_CLASS (klass)->read = nvertex_read;
-  GTS_OBJECT_CLASS (klass)->write = nvertex_write;
-}
-
-static void nvertex_init (GtsNVertex * nvertex)
-{
-  nvertex->name[0] = '\0';
-}
-
-/**
- * gts_nvertex_class:
- *
- * Returns: the #GtsNVertexClass.
- */
-GtsNVertexClass * gts_nvertex_class (void)
-{
-  static GtsNVertexClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo nvertex_info = {
-      "GtsNVertex",
-      sizeof (GtsNVertex),
-      sizeof (GtsNVertexClass),
-      (GtsObjectClassInitFunc) nvertex_class_init,
-      (GtsObjectInitFunc) nvertex_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_vertex_class ()), 
-				  &nvertex_info);
-  }
-
-  return klass;
-}
-
-static void nedge_read (GtsObject ** po, GtsFile * fp)
-{
-  if (fp->type != GTS_STRING) {
-    gts_file_error (fp, "expecting a string (name)");
-    return;
-  }
-  strncpy (GTS_NEDGE (*po)->name, fp->token->str, GTS_NAME_LENGTH);
-  gts_file_next_token (fp);
-}
-
-static void nedge_write (GtsObject * o, FILE * fptr)
-{
-  GtsNEdge * ne = GTS_NEDGE (o);
-
-  if (ne->name[0] != '\0')
-    fprintf (fptr, " %s", ne->name);
-}
-
-static void nedge_class_init (GtsNEdgeClass * klass)
-{
-  GTS_OBJECT_CLASS (klass)->read = nedge_read;
-  GTS_OBJECT_CLASS (klass)->write = nedge_write;
-}
-
-static void nedge_init (GtsNEdge * nedge)
-{
-  nedge->name[0] = '\0';
-}
-
-/**
- * gts_nedge_class:
- *
- * Returns: the #GtsNEdgeClass.
- */
-GtsNEdgeClass * gts_nedge_class (void)
-{
-  static GtsNEdgeClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo nedge_info = {
-      "GtsNEdge",
-      sizeof (GtsNEdge),
-      sizeof (GtsNEdgeClass),
-      (GtsObjectClassInitFunc) nedge_class_init,
-      (GtsObjectInitFunc) nedge_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_edge_class ()), 
-				  &nedge_info);
-  }
-
-  return klass;
-}
-
-static void nface_read (GtsObject ** po, GtsFile * fp)
-{
-  if (fp->type != GTS_STRING) {
-    gts_file_error (fp, "expecting a string (name)");
-    return;
-  }
-  strncpy (GTS_NFACE (*po)->name, fp->token->str, GTS_NAME_LENGTH);
-  gts_file_next_token (fp);
-}
-
-static void nface_write (GtsObject * o, FILE * fptr)
-{
-  GtsNFace * nf = GTS_NFACE (o);
-
-  if (nf->name[0] != '\0')
-    fprintf (fptr, " %s", GTS_NFACE (o)->name);
-}
-
-static void nface_class_init (GtsNFaceClass * klass)
-{
-  GTS_OBJECT_CLASS (klass)->read = nface_read;
-  GTS_OBJECT_CLASS (klass)->write = nface_write;
-}
-
-static void nface_init (GtsNFace * nface)
-{
-  nface->name[0] = '\0';
-}
-
-/**
- * gts_nface_class:
- *
- * Returns: the #GtsNFaceClass.
- */
-GtsNFaceClass * gts_nface_class (void)
-{
-  static GtsNFaceClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo nface_info = {
-      "GtsNFace",
-      sizeof (GtsNFace),
-      sizeof (GtsNFaceClass),
-      (GtsObjectClassInitFunc) nface_class_init,
-      (GtsObjectInitFunc) nface_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_face_class ()), 
-				  &nface_info);
-  }
-
-  return klass;
-}
diff --git a/src/gts/object.c b/src/gts/object.c
deleted file mode 100644
index 5970e50..0000000
--- a/src/gts/object.c
+++ /dev/null
@@ -1,345 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <string.h>
-#include "gts.h"
-#include "gts-private.h"
-
-static GHashTable * class_table = NULL;
-
-static void gts_object_class_init (GtsObjectClass * klass,
-				   GtsObjectClass * parent_class)
-{
-  if (parent_class) {
-    gts_object_class_init (klass, parent_class->parent_class);
-    if (parent_class->info.class_init_func)
-      (*parent_class->info.class_init_func) (klass);
-  }
-}
-
-/**
- * gts_object_class_new:
- * @parent_class: a #GtsObjectClass.
- * @info: a #GtsObjectClassInfo, description of the new class to create.
- *
- * Returns: a new #GtsObjectClass derived from @parent_class and described by
- * @info.
- */
-gpointer gts_object_class_new (GtsObjectClass * parent_class,
-			       GtsObjectClassInfo * info)
-{
-  GtsObjectClass * klass;
-
-  g_return_val_if_fail (info != NULL, NULL);
-  g_return_val_if_fail (parent_class == NULL ||
-			info->object_size >= parent_class->info.object_size,
-			NULL);
-  g_return_val_if_fail (parent_class == NULL ||
-			info->class_size >= parent_class->info.class_size,
-			NULL);
-
-  klass = g_malloc0 (info->class_size);
-  klass->info = *info;
-  klass->parent_class = parent_class;
-  gts_object_class_init (klass, klass);
-
-  if (!class_table)
-    class_table = g_hash_table_new (g_str_hash, g_str_equal);
-  g_hash_table_insert (class_table, klass->info.name, klass);
-
-  return klass;
-}
-
-/**
- * gts_object_class_from_name:
- * @name: the name of a #GtsObjectClass.
- *
- * Returns: the #GtsObjectClass with name @name or %NULL if it hasn't been 
- * instantiated yet.
- */
-GtsObjectClass * gts_object_class_from_name (const gchar * name)
-{
-  g_return_val_if_fail (name != NULL, NULL);
-
-  if (!class_table)
-    return NULL;
-  return g_hash_table_lookup (class_table, name);
-}
-
-static void object_destroy (GtsObject * object)
-{
-#ifdef DEBUG_IDENTITY
-#ifdef DEBUG_LEAKS
-  fprintf (stderr, "destroy %s %p->%d\n", 
-	   object->klass->info.name,
-	   object, 
-	   id (object));
-#endif
-  id_remove (object);
-#endif
-  object->klass = NULL;
-  g_free (object);
-}
-
-static void object_clone (GtsObject * clone, GtsObject * object)
-{
-  memcpy (clone, object, object->klass->info.object_size);
-  clone->reserved = NULL;
-}
-
-static void object_class_init (GtsObjectClass * klass)
-{
-  klass->clone = object_clone;
-  klass->destroy = object_destroy;
-  klass->read = NULL;
-  klass->write = NULL;
-  klass->color = NULL;  
-  klass->attributes = NULL;
-}
-
-static void object_init (GtsObject * object)
-{
-  object->reserved = NULL;
-  object->flags = 0;
-}
-
-/**
- * gts_object_class:
- *
- * Returns: the #GtsObjectClass.
- */
-GtsObjectClass * gts_object_class (void)
-{
-  static GtsObjectClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo object_info = {
-      "GtsObject",
-      sizeof (GtsObject),
-      sizeof (GtsObjectClass),
-      (GtsObjectClassInitFunc) object_class_init,
-      (GtsObjectInitFunc) object_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (NULL, &object_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_object_check_cast:
- * @object: a #GtsObject.
- * @klass: a #GtsObjectClass.
- *
- * Returns: @object while emitting warnings if @object is not of class @klass.
- */
-gpointer gts_object_check_cast (gpointer object, 
-				gpointer klass)
-{
-  if (!object) {
-    g_warning ("invalid cast from (NULL) pointer to `%s'",
-	       GTS_OBJECT_CLASS (klass)->info.name);
-    return object;
-  }
-  if (!((GtsObject *) object)->klass) {
-    g_warning ("invalid unclassed pointer in cast to `%s'",
-	       GTS_OBJECT_CLASS (klass)->info.name);
-    return object;
-  }
-  if (!gts_object_is_from_class (object, klass)) {
-    g_warning ("invalid cast from `%s' to `%s'",
-	       ((GtsObject *) object)->klass->info.name,
-	       GTS_OBJECT_CLASS (klass)->info.name);
-    return object;
-  }
-  return object;
-}
-
-/**
- * gts_object_class_check_cast:
- * @klass: a #GtsObjectClass.
- * @from: a #GtsObjectClass.
- *
- * Returns: @klass while emitting warnings if @klass is not derived from
- * @from.
- */
-gpointer gts_object_class_check_cast (gpointer klass, 
-				      gpointer from)
-{
-  if (!klass) {
-    g_warning ("invalid cast from (NULL) pointer to `%s'",
-	       GTS_OBJECT_CLASS (from)->info.name);
-    return klass;
-  }
-  if (!gts_object_class_is_from_class (klass, from)) {
-    g_warning ("invalid cast from `%s' to `%s'",
-	       GTS_OBJECT_CLASS (klass)->info.name,
-	       GTS_OBJECT_CLASS (from)->info.name);
-    return klass;
-  }
-  return klass;
-}
-
-/**
- * gts_object_init:
- * @object: a #GtsObject.
- * @klass: a #GtsObjectClass.
- *
- * Calls the init method of @klass with @object as argument. This is done 
- * recursively in the correct order (from the base class to the top). You
- * should rarely need this function as it is called automatically by the
- * constructor for each class.
- */
-void gts_object_init (GtsObject * object, GtsObjectClass * klass)
-{
-  GtsObjectClass * parent_class;
-
-  g_return_if_fail (object != NULL);
-  g_return_if_fail (klass != NULL);
-
-  parent_class = klass->parent_class;
-  if (parent_class)
-    gts_object_init (object, parent_class);
-  if (klass->info.object_init_func)
-    (*klass->info.object_init_func) (object);
-}
-
-/**
- * gts_object_new:
- * @klass: a #GtsObjectClass.
- *
- * Returns: a new initialized object of class @klass.
- */
-GtsObject * gts_object_new (GtsObjectClass * klass)
-{
-  GtsObject * object;
-
-  g_return_val_if_fail (klass != NULL, NULL);
-
-  object = g_malloc0 (klass->info.object_size);
-  object->klass = klass;
-  gts_object_init (object, klass);
-
-#ifdef DEBUG_IDENTITY
-  id_insert (object);
-#ifdef DEBUG_LEAKS
-  fprintf (stderr, "new %s %p->%d\n", klass->info.name, 
-	   object, 
-	   id (object));
-#endif
-#endif
-
-  return object;
-}
-
-/**
- * gts_object_clone:
- * @object: a #GtsObject.
- *
- * Calls the clone method of @object. The call to this function will fail
- * if no clone method exists for the given object.
- *
- * Returns: a new object clone of @object.
- */
-GtsObject * gts_object_clone (GtsObject * object)
-{
-  GtsObject * clone;
-
-  g_return_val_if_fail (object != NULL, NULL);
-  g_return_val_if_fail (object->klass->clone, NULL);
-
-  clone = g_malloc0 (object->klass->info.object_size);
-  clone->klass = object->klass;
-  object_init (clone);
-  (* object->klass->clone) (clone, object);
-
-#ifdef DEBUG_IDENTITY
-  id_insert (clone);
-#ifdef DEBUG_LEAKS
-  fprintf (stderr, "clone %s %p->%d\n", clone->klass->info.name, 
-	   clone, 
-	   id (clone));
-#endif
-#endif
-
-  return clone;
-}
-
-/**
- * gts_object_destroy:
- * @object: a #GtsObject.
- *
- * Calls the destroy method of @object, freeing all memory allocated for it.
- */
-void gts_object_destroy (GtsObject * object)
-{
-  g_assert (object->klass->destroy);
-  GTS_OBJECT_SET_FLAGS (object, GTS_DESTROYED);
-  (* object->klass->destroy) (object);
-}
-
-/**
- * gts_object_reset_reserved:
- * @object: a #GtsObject.
- *
- * Reset the reserved field of @object.
- */
-void gts_object_reset_reserved (GtsObject * object)
-{
-  g_return_if_fail (object != NULL);
-
-  object->reserved = NULL;
-}
-
-/**
- * gts_object_attributes:
- * @object: a #GtsObject.
- * @from: a #GtsObject.
- *
- * Calls the attributes() method of @object using @from as source.
- */
-void gts_object_attributes (GtsObject * object, GtsObject * from)
-{
-  g_return_if_fail (object != NULL);
-
-  if (object->klass->attributes)
-    (* object->klass->attributes) (object, from);
-}
-
-static void free_class (gchar * name, GtsObjectClass * klass)
-{
-  g_free (klass);
-}
-
-/**
- * gts_finalize:
- *
- * Free all the memory allocated by the object system of GTS. No other
- * GTS function can be called after this function has been called.
- */
-void gts_finalize (void)
-{
-  if (class_table) {
-    g_hash_table_foreach (class_table, (GHFunc) free_class, NULL);
-    g_hash_table_destroy (class_table);
-    class_table = NULL;
-  }
-}
diff --git a/src/gts/oocs.c b/src/gts/oocs.c
deleted file mode 100644
index f0d76bf..0000000
--- a/src/gts/oocs.c
+++ /dev/null
@@ -1,387 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <math.h>
-#include "gts.h"
-
-static void cluster_destroy (GtsObject * object)
-{
-  GtsCluster * c = GTS_CLUSTER (object);
-
-  if (c->v && gts_vertex_is_unattached (c->v))
-    gts_object_destroy (GTS_OBJECT (c->v));
-
-  /* do not forget to call destroy method of the parent */
-  (* GTS_OBJECT_CLASS (gts_cluster_class ())->parent_class->destroy) (object);
-}
-
-static void cluster_add (GtsCluster * c, GtsPoint * p, gpointer data)
-{
-  GtsPoint * cp;
-
-  g_return_if_fail (c != NULL);
-  g_return_if_fail (c->v != NULL);
-  g_return_if_fail (p != NULL);
-
-  cp = GTS_POINT (c->v);
-  
-  cp->x += p->x;
-  cp->y += p->y;
-  cp->z += p->z;
-  c->n++;
-}
-
-static void cluster_update (GtsCluster * c)
-{
-  GtsPoint * p;
-
-  g_return_if_fail (c != NULL);
-  g_return_if_fail (c->v != NULL);
-
-  if (c->n > 1) {
-    p = GTS_POINT (c->v);
-    p->x /= c->n;
-    p->y /= c->n;
-    p->z /= c->n;
-  }
-}
-
-static void cluster_class_init (GtsClusterClass * klass)
-{
-  klass->add = cluster_add;
-  klass->update = cluster_update;
-
-  GTS_OBJECT_CLASS (klass)->destroy = cluster_destroy;
-}
-
-static void cluster_init (GtsCluster * c)
-{
-  c->v = NULL;
-  c->n = 0;
-}
-
-/**
- * gts_cluster_class:
- *
- * Returns: the #GtsClusterClass.
- */
-GtsClusterClass * gts_cluster_class (void)
-{
-  static GtsClusterClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo cluster_info = {
-      "GtsCluster",
-      sizeof (GtsCluster),
-      sizeof (GtsClusterClass),
-      (GtsObjectClassInitFunc) cluster_class_init,
-      (GtsObjectInitFunc) cluster_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (gts_object_class (), &cluster_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_cluster_new:
- * @klass: a #GtsClusterClass.
- * @id: the id of the new cluster.
- * @vklass: a #GtsVertexClass for the representative vertex of the cluster.
- *
- * Returns: a new #GtsCluster.
- */
-GtsCluster * gts_cluster_new (GtsClusterClass * klass,
-			      GtsClusterId id,
-			      GtsVertexClass * vklass)
-{
-  GtsCluster * c;
-
-  c = GTS_CLUSTER (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  c->id = id;
-  c->v = gts_vertex_new (vklass, 0., 0., 0.);
-
-  return c;
-}
-
-/**
- * gts_cluster_add:
- * @c: a #GtsCluster.
- * @p: a #GtsPoint.
- * @data: data to pass to the add() virtual method of #GtsClusterClass.
- *
- * Adds point @p to cluster @c.
- */
-void gts_cluster_add (GtsCluster * c, GtsPoint * p, gpointer data)
-{
-  g_return_if_fail (c != NULL);
-  g_return_if_fail (p != NULL);
-
-  (* GTS_CLUSTER_CLASS (GTS_OBJECT (c)->klass)->add) (c, p, data);
-}
-
-/**
- * gts_cluster_update:
- * @c: a #GtsCluster.
- *
- * Updates the position of the vertex representative of all the
- * vertices added to @c.  
- */
-void gts_cluster_update (GtsCluster * c)
-{
-  g_return_if_fail (c != NULL);
-
-  (* GTS_CLUSTER_CLASS (GTS_OBJECT (c)->klass)->update) (c);
-}
-
-static void destroy_cluster (GtsClusterId * id, GtsObject * cluster)
-{
-  gts_object_destroy (cluster);
-}
-
-static void cluster_grid_destroy (GtsObject * object)
-{
-  GtsClusterGrid * cluster_grid = GTS_CLUSTER_GRID (object);
-
-  g_hash_table_foreach (cluster_grid->clusters, 
-			(GHFunc) destroy_cluster, NULL);
-  g_hash_table_destroy (cluster_grid->clusters);
-  
-  (* GTS_OBJECT_CLASS (gts_cluster_grid_class ())->parent_class->destroy) 
-    (object);
-}
-
-static void cluster_grid_class_init (GtsClusterGridClass * klass)
-{
-  GTS_OBJECT_CLASS (klass)->destroy = cluster_grid_destroy;
-}
-
-static gint cluster_id_equal (gconstpointer v1,
-			      gconstpointer v2)
-{
-  const GtsClusterId * id1 = (const GtsClusterId *) v1;
-  const GtsClusterId * id2 = (const GtsClusterId *) v2;
-  return ((id1->x == id2->x) && (id1->y == id2->y) && (id1->z == id2->z));
-}
-
-static guint cluster_id_hash (gconstpointer key)
-{
-  const GtsClusterId * id = (const GtsClusterId *) key;
-  return id->x + id->y + id->z;
-}
-
-static void cluster_grid_init (GtsClusterGrid * cluster_grid)
-{
-  cluster_grid->surface = NULL;
-  cluster_grid->bbox = NULL;
-  cluster_grid->cluster_class = gts_cluster_class ();
-  cluster_grid->clusters = g_hash_table_new (cluster_id_hash,
-					      cluster_id_equal);
-}
-
-/**
- * gts_cluster_grid_class:
- *
- * Returns: the #GtsClusterGridClass.
- */
-GtsClusterGridClass * gts_cluster_grid_class (void)
-{
-  static GtsClusterGridClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo cluster_grid_info = {
-      "GtsClusterGrid",
-      sizeof (GtsClusterGrid),
-      sizeof (GtsClusterGridClass),
-      (GtsObjectClassInitFunc) cluster_grid_class_init,
-      (GtsObjectInitFunc) cluster_grid_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (gts_object_class (), &cluster_grid_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_cluster_grid_new:
- * @klass: a #GtsClusterGridClass.
- * @cluster_class: the klass to be used for the vertex clusters.
- * @s: the simplified surface.
- * @bbox: bounding box of the surface to be simplified.
- * @delta: the size of one grid cell of the simplification grid.
- *
- * Returns: a new #GtsClusterGrid.
- */
-GtsClusterGrid * gts_cluster_grid_new (GtsClusterGridClass * klass,
-				       GtsClusterClass * cluster_class,
-				       GtsSurface * s,
-				       GtsBBox * bbox,
-				       gdouble delta)
-{
-  GtsClusterGrid * cluster_grid;
-  GtsVector size;
-
-  g_return_val_if_fail (klass != NULL, NULL);
-  g_return_val_if_fail (cluster_class != NULL, NULL);
-  g_return_val_if_fail (s != NULL, NULL);
-  g_return_val_if_fail (bbox != NULL, NULL);
-  g_return_val_if_fail (delta > 0., NULL);
-
-  size[0] = ceil ((bbox->x2 - bbox->x1)/delta);
-  size[1] = ceil ((bbox->y2 - bbox->y1)/delta);
-  size[2] = ceil ((bbox->z2 - bbox->z1)/delta);
-  g_return_val_if_fail (size[0] <= 2.*G_MAXINT + 2. &&
-			size[1] <= 2.*G_MAXINT + 2. &&
-			size[2] <= 2.*G_MAXINT + 2., NULL);
-  cluster_grid = 
-    GTS_CLUSTER_GRID (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  cluster_grid->cluster_class = cluster_class;
-  cluster_grid->surface = s;
-  cluster_grid->bbox = bbox;
-  cluster_grid->size[0] = size[0];
-  cluster_grid->size[1] = size[1];
-  cluster_grid->size[2] = size[2];
-
-  return cluster_grid;
-}
-
-static GtsClusterId cluster_index (GtsPoint * p,
-				   GtsBBox * bb,
-				   GtsVector n)
-{
-  GtsClusterId id = {0, 0, 0};
-  
-  g_return_val_if_fail (p->x >= bb->x1 && p->x <= bb->x2, id);
-  g_return_val_if_fail (p->y >= bb->y1 && p->y <= bb->y2, id);
-  g_return_val_if_fail (p->z >= bb->z1 && p->z <= bb->z2, id);
-  
-  id.x = (guint) (p->x == bb->x2 ? n[0] - 1. : n[0]*(p->x - bb->x1)/(bb->x2 - bb->x1));
-  id.y = (guint) (p->y == bb->y2 ? n[1] - 1. : n[1]*(p->y - bb->y1)/(bb->y2 - bb->y1));
-  id.z = (guint) (p->z == bb->z2 ? n[2] - 1. : n[2]*(p->z - bb->z1)/(bb->z2 - bb->z1));
-
-  return id;
-}
-
-static GtsCluster * cluster_grid_add_point (GtsClusterGrid * cluster_grid,
-					    GtsPoint * p,
-					    gpointer data)
-{
-  GtsClusterId id = cluster_index (p, 
-				   cluster_grid->bbox, 
-				   cluster_grid->size);
-  GtsCluster * c = g_hash_table_lookup (cluster_grid->clusters, &id);
-
-  if (c == NULL) {
-    c = gts_cluster_new (cluster_grid->cluster_class, id, 
-			 cluster_grid->surface->vertex_class);
-    g_hash_table_insert (cluster_grid->clusters, &c->id, c);
-  }
-  
-  gts_cluster_add (c, p, data);
-  
-  return c;
-}
-
-/**
- * gts_cluster_grid_add_triangle:
- * @cluster_grid: a #GtsClusterGrid.
- * @p1: a #GtsPoint.
- * @p2: a #GtsPoint.
- * @p3: a #GtsPoint.
- * @data: user data to pass to the cluster add() method.
- *
- * Adds the triangle defined by @p1, @p2 and @p3 to the respective clusters
- * of @cluster_grid.
- */
-void gts_cluster_grid_add_triangle (GtsClusterGrid * cluster_grid,
-				    GtsPoint * p1,
-				    GtsPoint * p2,
-				    GtsPoint * p3,
-				    gpointer data)
-{
-  GtsCluster * c1, * c2, * c3;
-
-  g_return_if_fail (cluster_grid != NULL);
-  g_return_if_fail (p1 != NULL);
-  g_return_if_fail (p2 != NULL);
-  g_return_if_fail (p3 != NULL);
-  g_return_if_fail (cluster_grid->surface != NULL);
-
-  c1 = cluster_grid_add_point (cluster_grid, p1, data);
-  c2 = cluster_grid_add_point (cluster_grid, p2, data);
-  c3 = cluster_grid_add_point (cluster_grid, p3, data);
-  
-  if (c1 != c2 && c2 != c3 && c3 != c1) {
-    GtsVertex * v1, * v2, * v3;
-    GtsEdge * e1, * e2, * e3;
-    gboolean new_edge = FALSE;
-    
-    v1 = c1->v; v2 = c2->v; v3 = c3->v;
-
-    if ((e1 = GTS_EDGE (gts_vertices_are_connected (v1, v2))) == NULL) {
-      e1 = gts_edge_new (cluster_grid->surface->edge_class, v1, v2);
-      new_edge = TRUE;
-    }
-    if ((e2 = GTS_EDGE (gts_vertices_are_connected (v2, v3))) == NULL) {
-      e2 = gts_edge_new (cluster_grid->surface->edge_class, v2, v3);
-      new_edge = TRUE;
-    }
-    if ((e3 = GTS_EDGE (gts_vertices_are_connected (v3, v1))) == NULL) {
-      e3 = gts_edge_new (cluster_grid->surface->edge_class, v3, v1);
-      new_edge = TRUE;
-    }
-    if (new_edge || !gts_triangle_use_edges (e1, e2, e3))
-      gts_surface_add_face (cluster_grid->surface, 
-			    gts_face_new (cluster_grid->surface->face_class, 
-					  e1, e2, e3));
-  }
-}
-
-static void update_cluster (gint * id, GtsCluster * cluster, GtsRange * stats)
-{
-  gts_cluster_update (cluster);
-  gts_range_add_value (stats, cluster->n);
-}
-
-/**
- * gts_cluster_grid_update:
- * @cluster_grid: a #GtsClusterGrid.
- *
- * Updates the representative vertices of all the clusters of @cluster_grid.
- *
- * Returns: a #GtsRange describing the statistics for the number of vertices
- * added to each cluster of @cluster_grid.
- */
-GtsRange gts_cluster_grid_update (GtsClusterGrid * cluster_grid)
-{
-  GtsRange stats;
-
-  gts_range_init (&stats);
-  g_return_val_if_fail (cluster_grid != NULL, stats);
-
-  g_hash_table_foreach (cluster_grid->clusters, 
-			(GHFunc) update_cluster, &stats);
-  gts_range_update (&stats);
-
-  return stats;
-}
diff --git a/src/gts/partition.c b/src/gts/partition.c
deleted file mode 100644
index 16dc0e1..0000000
--- a/src/gts/partition.c
+++ /dev/null
@@ -1,1219 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <math.h>
-
-#include "gts.h"
-
-/* #define DEBUG */
-
-/* Graph partition */
-
-/**
- * gts_graph_partition_edges_cut:
- * @partition: a list of @GtsGraph representing a partition.
- *
- * Returns: the number of edges cut by the partition.
- */
-guint gts_graph_partition_edges_cut (GSList * partition)
-{
-  guint cuts = 0;
-
-  while (partition) {
-    cuts += gts_graph_edges_cut (partition->data);
-    partition = partition->next;
-  }
-
-  return cuts/2;
-}
-
-/**
- * gts_graph_partition_edges_cut_weight:
- * @partition: a list of @GtsGraph representing a partition.
- *
- * Returns: the total weight of the edges cut by the partition.
- */
-gfloat gts_graph_partition_edges_cut_weight (GSList * partition)
-{
-  gfloat weight = 0.;
-
-  while (partition) {
-    weight += gts_graph_edges_cut_weight (partition->data);
-    partition = partition->next;
-  }
-
-  return weight/2.;
-}
-
-/**
- * gts_graph_partition_print_stats:
- * @partition: a list of @GtsGraph representing a partition.
- * @fp: a file pointer.
- *
- * Writes to @fp a summary of the properties of @partition.
- */
-void gts_graph_partition_print_stats (GSList * partition,
-				      FILE * fp)
-{
-  GtsRange weight;
-  GSList * i;
-
-  g_return_if_fail (partition != NULL);
-  g_return_if_fail (fp != NULL);
-
-  gts_range_init (&weight);
-  i = partition;
-  while (i) {
-    gts_range_add_value (&weight, gts_graph_weight (i->data));
-    i = i->next;
-  }
-  gts_range_update (&weight);
-
-  fprintf (fp, 
-	   "# parts: %d\n"
-	   "#   edge cuts: %5d edge cuts weight: %5g\n"
-	   "#   weight: ",
-	   g_slist_length (partition),
-	   gts_graph_partition_edges_cut (partition),
-	   gts_graph_partition_edges_cut_weight (partition));
-  gts_range_print (&weight, fp);
-  fputc ('\n', fp);
-}
-
-/**
- * gts_graph_partition_balance:
- * @partition: a list of @GtsGraph representing a partition.
- *
- * Returns: the difference between the maximum and the minimum weight
- * of the graphs in @partition.  
- */
-gfloat gts_graph_partition_balance (GSList * partition)
-{
-  gfloat wmin = G_MAXFLOAT;
-  gfloat wmax = - G_MAXFLOAT;
-
-  g_return_val_if_fail (partition != NULL, 0.);
-
-  while (partition) {
-    gfloat weight = gts_graph_weight (partition->data);
-    if (weight < wmin)
-      wmin = weight;
-    if (weight > wmax)
-      wmax = weight;
-    partition = partition->next;
-  }
-  return wmax - wmin;
-}
-
-/**
- * gts_graph_partition_clone:
- * @partition: a list of @GtsGraph representing a partition.
- *
- * Returns: a new partition clone of @partition (i.e. a list of new
- * graphs clones of the graphs in @partition).  
- */
-GSList * gts_graph_partition_clone (GSList * partition)
-{
-  GSList * cparts = NULL;
-
-  while (partition) {
-    cparts = 
-      g_slist_prepend (cparts, 
-		       gts_object_clone (GTS_OBJECT (partition->data)));
-    partition = partition->next;
-  }
-  return cparts;
-}
-
-/**
- * gts_graph_partition_destroy:
- * @partition: a list of @GtsGraph representing a partition.
- *
- * Destroys all the graphs in @partition and frees @partition.
- */
-void gts_graph_partition_destroy (GSList * partition)
-{
-  GSList * i = partition;
-
-  while (i) {
-    gts_object_destroy (GTS_OBJECT (i->data));
-    i = i->next;
-  }
-  g_slist_free (partition);
-}
-
-static void find_smallest_degree (GtsGNode * n, gpointer * data)
-{
-  GtsGNode ** nmin = data[0];
-  GtsGraph * g = data[1];
-  guint * min = data[2];
-  guint degree = gts_gnode_degree (n, g);
-
-  if (degree < *min) {
-    *min = degree;
-    *nmin = n;
-  }
-}
-
-static gint graph_comp_weight (GtsGraph * g1, GtsGraph * g2)
-{
-  if (gts_graph_weight (g1) > gts_graph_weight (g2))
-    return 1;
-  return -1;
-}
-
-static void partition_update (GSList * list, GtsGraph * g)
-{
-  GSList * i;
-  GtsGraph * g1;
-  GtsHeap * size_heap;
-  gboolean reinit = TRUE;
-
-  /* initialize traversals */
-  i = list;
-  while (i) {
-    GtsGNode * seed = GTS_OBJECT (i->data)->reserved;
-    GTS_OBJECT (seed)->reserved = 
-      gts_graph_traverse_new (g, seed, GTS_BREADTH_FIRST, reinit);
-    reinit = FALSE;
-    i = i->next;
-  }
-  
-  size_heap = gts_heap_new ((GCompareFunc) graph_comp_weight);
-  i = list;
-  while (i) {
-    gts_heap_insert (size_heap, i->data);
-    i = i->next;
-  }
-  while ((g1 = gts_heap_remove_top (size_heap))) {
-    GtsGraphTraverse * t = GTS_OBJECT (GTS_OBJECT (g1)->reserved)->reserved;
-    GtsGNode * n = gts_graph_traverse_next (t);
-    if (n) {
-      gts_container_add (GTS_CONTAINER (g1), GTS_CONTAINEE (n));
-      gts_heap_insert (size_heap, g1);
-    }
-  }
-  gts_heap_destroy (size_heap);
-
-  /* destroy traversals */
-  i = list;
-  while (i) {
-    GtsGNode * seed = GTS_OBJECT (i->data)->reserved;
-    gts_graph_traverse_destroy (GTS_OBJECT (seed)->reserved);
-    GTS_OBJECT (seed)->reserved = NULL;
-    i = i->next;
-  }
-}
-
-static void better_seed (GtsGNode * n, gpointer * data)
-{
-  guint * sum = data[0];
-  GtsGNode ** seed = data[1];
-  GtsGraph * g = data[2];
-  guint sum1 = gts_graph_distance_sum (g, n);
-  
-  if (sum1 < *sum) {
-    *sum = sum1;
-    *seed = n;
-  }
-}
-
-static GtsGNode * graph_new_seed (GtsGraph * g, GtsGNode * seed)
-{
-  guint sum = gts_graph_distance_sum (g, seed);
-  gpointer data[3];
-  GtsGNode * new_seed = seed;
-
-  data[0] = &sum;
-  data[1] = &new_seed;
-  data[2] = g;
-  gts_gnode_foreach_neighbor (seed, g, (GtsFunc) better_seed, data);
-
-  return new_seed;
-}
-
-/**
- * gts_graph_bubble_partition:
- * @g: a #GtsGraph.
- * @np: number of partitions.
- * @niter: the maximum number of iterations.
- * @step_info: a #GtsFunc or %NULL.
- * @data: user data to pass to @step_info.
- *
- * An implementation of the "bubble partitioning algorithm" of
- * Diekmann, Preis, Schlimbach and Walshaw (2000). The maximum number
- * of iteration on the positions of the graph growing seeds is
- * controlled by @niter.
- *
- * If not %NULL @step_info is called after each iteration on the seeds
- * positions passing the partition (a GSList) as argument.
- *
- * Returns: a list of @np new #GtsGraph representing the partition.  
- */
-GSList * gts_graph_bubble_partition (GtsGraph * g, 
-				     guint np, 
-				     guint niter,
-				     GtsFunc step_info,
-				     gpointer data)
-{
-  GSList * list = NULL, * seeds = NULL;
-  GtsGNode * seed = NULL;
-  guint min = G_MAXINT/2 - 1;
-  gpointer info[3];
-  GtsGraph * g1;
-  gboolean changed = TRUE;
-
-  g_return_val_if_fail (g != NULL, NULL);
-  g_return_val_if_fail (np > 0, NULL);
-
-  info[0] = &seed;
-  info[1] = g;
-  info[2] = &min;
-  gts_container_foreach (GTS_CONTAINER (g), 
-			 (GtsFunc) find_smallest_degree,
-			 info);
-  if (seed == NULL)
-    return NULL;
-
-  g1 = GTS_GRAPH (gts_object_new (GTS_OBJECT (g)->klass));
-  gts_container_add (GTS_CONTAINER (g1), GTS_CONTAINEE (seed));
-  list = g_slist_prepend (list, g1);
-  GTS_OBJECT (g1)->reserved = seed;
-  seeds = g_slist_prepend (seeds, seed);
-
-  while (--np && seed)
-    if ((seed = gts_graph_farthest (g, seeds))) {
-      g1 = GTS_GRAPH (gts_object_new (GTS_OBJECT (g)->klass));
-      gts_container_add (GTS_CONTAINER (g1), GTS_CONTAINEE (seed));
-      list = g_slist_prepend (list, g1);
-      GTS_OBJECT (g1)->reserved = seed;
-      seeds = g_slist_prepend (seeds, seed);
-    }
-  g_slist_free (seeds);
-  
-  partition_update (list, g);
-
-  while (changed && niter--) {
-    GSList * i;
-
-    changed = FALSE;
-    i = list;
-    while (i) {
-      GtsGraph * g1 = i->data;
-      GtsGNode * seed = GTS_OBJECT (g1)->reserved;
-      GtsGNode * new_seed = graph_new_seed (g1, seed);
-      if (new_seed != seed) {
-	changed = TRUE;
-	GTS_OBJECT (g1)->reserved = new_seed;
-      }
-      i = i->next;
-    }
-
-    if (changed) {
-      i = list;
-      while (i) {
-	GtsGraph * g1 = i->data;
-	GtsGNode * seed = GTS_OBJECT (g1)->reserved;
-
-	gts_object_destroy (GTS_OBJECT (g1));
-	i->data = g1 = GTS_GRAPH (gts_object_new (GTS_OBJECT (g)->klass));
-	gts_container_add (GTS_CONTAINER (g1), GTS_CONTAINEE (seed));
-	GTS_OBJECT (g1)->reserved = seed;
-	i = i->next;
-      }
-      partition_update (list, g);
-      if (step_info)
-	(* step_info) (list, data);
-    }
-  }
-  g_slist_foreach (list, (GFunc) gts_object_reset_reserved, NULL);
-  return list;
-}
-
-/* Graph bisection */
-
-static gdouble node_cost (GtsGNode * n, gpointer * data)
-{
-  GtsGraph * g = data[0];
-  GtsGraph * g1 = data[1];
-  GSList * i = GTS_SLIST_CONTAINER (n)->items;
-  gdouble cost = 0.;
-
-  while (i) {
-    GtsGEdge * e = i->data;
-    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, e);
-
-    if (gts_containee_is_contained (GTS_CONTAINEE (n1), GTS_CONTAINER (g))) {
-      if (gts_containee_is_contained (GTS_CONTAINEE (n1), GTS_CONTAINER (g1)))
-	cost -= gts_gedge_weight (e);
-      else 
-	cost += gts_gedge_weight (e);
-    }
-    i = i->next;
-  }
-
-  return cost;
-}
-
-static void add_neighbor (GtsGNode * n, GtsEHeap * heap)
-{
-  if (GTS_OBJECT (n)->reserved == n)
-    return;
-  if (GTS_OBJECT (n)->reserved)
-    gts_eheap_remove (heap, GTS_OBJECT (n)->reserved);
-  GTS_OBJECT (n)->reserved = gts_eheap_insert (heap, n);
-}
-
-static void add_unused (GtsGNode * n, GtsGraph * g2)
-{
-  if (GTS_OBJECT (n)->reserved)
-    GTS_OBJECT (n)->reserved = NULL;
-  else
-    gts_container_add (GTS_CONTAINER (g2), GTS_CONTAINEE (n));
-}
-
-static gdouble degree_cost (GtsGNode * n, GtsGraph * g)
-{
-  return gts_gnode_degree (n, g); 
-}
-
-static void add_seed (GtsGNode * n, GtsEHeap * heap)
-{
-  gts_eheap_insert (heap, n);
-}
-
-static void boundary_node1 (GtsGNode * n, GtsGraphBisection * bg)
-{
-  GSList * i = GTS_SLIST_CONTAINER (n)->items;
-
-  while (i) {
-    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
-    if (gts_containee_is_contained (GTS_CONTAINEE (n1), 
-				    GTS_CONTAINER (bg->g2))) {
-      g_hash_table_insert (bg->bg1, n, n1);
-      return;
-    }
-    i = i->next;
-  }
-}
-
-static void boundary_node2 (GtsGNode * n, GtsGraphBisection * bg)
-{
-  GSList * i = GTS_SLIST_CONTAINER (n)->items;
-
-  while (i) {
-    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
-    if (gts_containee_is_contained (GTS_CONTAINEE (n1), 
-				    GTS_CONTAINER (bg->g1))) {
-      g_hash_table_insert (bg->bg2, n, n1);
-      return;
-    }
-    i = i->next;
-  }
-}
-
-static void check_bg (GtsGNode * n, gpointer * data)
-{
-  GHashTable * bg = data[0];
-  GtsGraph * g = data[1];
-  gboolean * ok = data[2];
-  guint * nb = data[3];
-  guint nn = gts_gnode_degree (n, g);
-
-  if (nn > 0)
-    (*nb)++;
-  if ((nn > 0 && !g_hash_table_lookup (bg, n)) ||
-      (nn == 0 && g_hash_table_lookup (bg, n))) {
-    g_warning ("nn: %d lookup: %p\n",
-	       nn, g_hash_table_lookup (bg, n));
-    *ok = FALSE;
-  }
-}
-
-/**
- * gts_graph_bisection_check:
- * @bg: a #GtsGraphBisection.
- *
- * Checks that the boundary of @bg is correctly defined (used for
- * debugging purposes).
- *
- * Returns: %TRUE if @bg is ok, %FALSE otherwise.  
- */
-gboolean gts_graph_bisection_check (GtsGraphBisection * bg)
-{
-  gboolean ok = TRUE;
-  guint nb;
-  gpointer data[4];
-
-  g_return_val_if_fail (bg != NULL, FALSE);
-
-  nb = 0;
-  data[0] = bg->bg1;
-  data[1] = bg->g2;
-  data[2] = &ok;
-  data[3] = &nb;
-  gts_container_foreach (GTS_CONTAINER (bg->g1), (GtsFunc) check_bg, data);
-  g_return_val_if_fail (g_hash_table_size (bg->bg1) == nb, FALSE);
-
-  nb = 0;
-  data[0] = bg->bg2;
-  data[1] = bg->g1;
-  gts_container_foreach (GTS_CONTAINER (bg->g2), (GtsFunc) check_bg, data);
-  g_return_val_if_fail (g_hash_table_size (bg->bg2) == nb, FALSE);
-
-  return ok;
-}
-
-/**
- * gts_graph_ggg_bisection:
- * @g: a #GtsGraph.
- * @ntry: the number of randomly selected initial seeds.
- *
- * An implementation of the "Greedy Graph Growing" algorithm of
- * Karypis and Kumar (1997).  
- *
- * @ntry randomly chosen seeds are used and the best partition is retained.
- *
- * Returns: a new #GtsGraphBisection of @g.
- */
-GtsGraphBisection * gts_graph_ggg_bisection (GtsGraph * g, guint ntry)
-{
-  gfloat size, bestcost = G_MAXFLOAT, smin;
-  GtsGraph * bestg1 = NULL, * bestg2 = NULL;
-  gboolean balanced = FALSE;
-  GtsEHeap * degree_heap;
-  GtsGNode * seed;
-  GtsGraphBisection * bg;
-
-  g_return_val_if_fail (g != NULL, NULL);
-
-  bg = g_malloc (sizeof (GtsGraphBisection));
-  bg->g = g;
-
-  size = gts_graph_weight (g)/2.;
-  smin = 0.9*size;
-
-  degree_heap = gts_eheap_new ((GtsKeyFunc) degree_cost, g);
-  gts_eheap_freeze (degree_heap);
-  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) add_seed, degree_heap);
-  gts_eheap_thaw (degree_heap);
-
-  while (ntry && ((seed = gts_eheap_remove_top (degree_heap, NULL)))) {
-    GtsGraph * g1, * g2;
-    GtsGNode * n;
-    gdouble cost;
-    gpointer data[2];
-    GtsEHeap * heap;
-  
-    g1 = gts_graph_new (GTS_GRAPH_CLASS (GTS_OBJECT (g)->klass),
-			g->node_class, g->edge_class);
-    g2 = gts_graph_new (GTS_GRAPH_CLASS (GTS_OBJECT (g)->klass),
-			g->node_class, g->edge_class);
-    
-    data[0] = g;
-    data[1] = g1;
-    heap = gts_eheap_new ((GtsKeyFunc) node_cost, data);
-
-    gts_container_add (GTS_CONTAINER (g1), GTS_CONTAINEE (seed));
-    GTS_OBJECT (seed)->reserved = seed;
-    gts_gnode_foreach_neighbor (seed, g, (GtsFunc) add_neighbor, heap);
-
-    while ((n = gts_eheap_remove_top (heap, &cost)))
-      if (gts_graph_weight (g1) + gts_gnode_weight (n) <= size) {
-	gts_container_add (GTS_CONTAINER (g1), GTS_CONTAINEE (n));
-	GTS_OBJECT (n)->reserved = n;
-	gts_gnode_foreach_neighbor (n, g, (GtsFunc) add_neighbor, heap);
-      }
-      else
-	GTS_OBJECT (n)->reserved = NULL;
-    gts_eheap_destroy (heap);
-    
-    gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) add_unused, g2);
-
-    cost = gts_graph_edges_cut_weight (g1);
-    if (!bestg1 || 
-	(!balanced && gts_graph_weight (g1) >= smin) ||
-	(cost < bestcost && gts_graph_weight (g1) >= smin)) {
-      if (bestg1)
-	bestcost = cost;
-      if (bestg1)
-	gts_object_destroy (GTS_OBJECT (bestg1));
-      if (bestg2)
-	gts_object_destroy (GTS_OBJECT (bestg2));
-      bestg1 = g1;
-      bestg2 = g2;
-      if (gts_graph_weight (g1) >= smin)
-	balanced = TRUE;
-    }
-    else {
-      gts_object_destroy (GTS_OBJECT (g1));
-      gts_object_destroy (GTS_OBJECT (g2));
-    }
-
-    ntry--;
-  }
-  gts_eheap_destroy (degree_heap);
-
-#ifdef DEBUG
-  fprintf (stderr, "bestcost: %5g g1: %5g|%5d g2: %5g|%5d\n",
-	   bestcost, 
-	   gts_graph_weight (bestg1), 
-	   gts_container_size (GTS_CONTAINER (bestg1)),
-	   gts_graph_weight (bestg2), 
-	   gts_container_size (GTS_CONTAINER (bestg2)));
-#endif
-
-  g_assert (bestg1 != NULL);
-  bg->g1 = bestg1;
-  g_assert (bestg2 != NULL);
-  bg->g2 = bestg2;
-  
-  /* boundary nodes */
-  bg->bg1 = g_hash_table_new (NULL, NULL);
-  gts_container_foreach (GTS_CONTAINER (bg->g1), (GtsFunc) boundary_node1, bg);
-  bg->bg2 = g_hash_table_new (NULL, NULL);
-  gts_container_foreach (GTS_CONTAINER (bg->g2), (GtsFunc) boundary_node2, bg);
-
-  return bg;
-}
-
-/**
- * gts_graph_bfgg_bisection:
- * @g: a #GtsGraph.
- * @ntry: the number of randomly selected initial seeds.
- *
- * An implementation of a "Breadth-First Graph Growing" algorithm.
- *
- * @ntry randomly chosen seeds are used and the best partition is retained.
- *
- * Returns: a new #GtsGraphBisection of @g.
- */
-GtsGraphBisection * gts_graph_bfgg_bisection (GtsGraph * g, guint ntry)
-{
-  gfloat size, bestcost = G_MAXFLOAT, smin;
-  GtsGraph * bestg1 = NULL, * bestg2 = NULL;
-  GtsEHeap * degree_heap;
-  GtsGNode * seed;
-  GtsGraphBisection * bg;
-
-  g_return_val_if_fail (g != NULL, NULL);
-
-  bg = g_malloc (sizeof (GtsGraphBisection));
-  bg->g = g;
-
-  size = gts_graph_weight (g)/2.;
-  smin = 0.9*size;
-
-  degree_heap = gts_eheap_new ((GtsKeyFunc) degree_cost, g);
-  gts_eheap_freeze (degree_heap);
-  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) add_seed, degree_heap);
-  gts_eheap_thaw (degree_heap);
-
-  while (ntry && ((seed = gts_eheap_remove_top (degree_heap, NULL)))) {
-    GtsGraph * g1, * g2;
-    GtsGNode * n;
-    gdouble cost;
-    GtsGraphTraverse * t = gts_graph_traverse_new (g, seed, 
-						   GTS_BREADTH_FIRST, TRUE);
-    
-    g1 = gts_graph_new (GTS_GRAPH_CLASS (GTS_OBJECT (g)->klass),
-			g->node_class, g->edge_class);
-    g2 = gts_graph_new (GTS_GRAPH_CLASS (GTS_OBJECT (g)->klass),
-			g->node_class, g->edge_class);
-
-    while ((n = gts_graph_traverse_next (t)))
-      if (gts_graph_weight (g1) + gts_gnode_weight (n) <= size) {
-	gts_container_add (GTS_CONTAINER (g1), GTS_CONTAINEE (n));
-	GTS_OBJECT (n)->reserved = n;
-      }
-    gts_graph_traverse_destroy (t);
-    
-    gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) add_unused, g2);
-
-    cost = gts_graph_edges_cut_weight (g1);
-    if (!bestg1 || (cost < bestcost && gts_graph_weight (g1) >= smin)) {
-      if (bestg1)
-	bestcost = cost;
-      if (bestg1)
-	gts_object_destroy (GTS_OBJECT (bestg1));
-      if (bestg2)
-	gts_object_destroy (GTS_OBJECT (bestg2));
-      bestg1 = g1;
-      bestg2 = g2;
-    }
-    else {
-      gts_object_destroy (GTS_OBJECT (g1));
-      gts_object_destroy (GTS_OBJECT (g2));
-    }
-
-    ntry--;
-  }
-  gts_eheap_destroy (degree_heap);
-
-#ifdef DEBUG
-  fprintf (stderr, "bestcost: %5g g1: %5g|%5d g2: %5g|%5d\n",
-	   bestcost, 
-	   gts_graph_weight (bestg1), 
-	   gts_container_size (GTS_CONTAINER (bestg1)),
-	   gts_graph_weight (bestg2), 
-	   gts_container_size (GTS_CONTAINER (bestg2)));
-#endif
-
-  bg->g1 = bestg1;
-  bg->g2 = bestg2;
-  
-  /* boundary nodes */
-  bg->bg1 = g_hash_table_new (NULL, NULL);
-  gts_container_foreach (GTS_CONTAINER (bg->g1), (GtsFunc) boundary_node1, bg);
-  bg->bg2 = g_hash_table_new (NULL, NULL);
-  gts_container_foreach (GTS_CONTAINER (bg->g2), (GtsFunc) boundary_node2, bg);
-
-  return bg;
-}
-
-static gdouble node_move_cost1 (GtsGNode * n, GtsGraphBisection * bg)
-{
-  return gts_gnode_move_cost (n, bg->g1, bg->g2);
-}
-
-static gdouble node_move_cost2 (GtsGNode * n, GtsGraphBisection * bg)
-{
-  return gts_gnode_move_cost (n, bg->g2, bg->g1);
-}
-
-static void build_heap (GtsGNode * n, GtsEHeap * heap)
-{
-  GTS_OBJECT (n)->reserved = gts_eheap_insert (heap, n);
-}
-
-/**
- * gts_graph_bisection_kl_refine:
- * @bg: a #GtsGraphBisection.
- * @mmax: the maximum number of unsuccessful successive moves.
- *
- * An implementation of the simplified Kernighan-Lin algorithm for
- * graph bisection refinement as described in Karypis and Kumar
- * (1997).
- *
- * The algorithm stops if @mmax consecutive modes do not lead to a
- * decrease in the number of edges cut. This last @mmax moves are
- * undone.
- *
- * Returns: the decrease in the weight of the edges cut by the bisection.  
- */
-gdouble gts_graph_bisection_kl_refine (GtsGraphBisection * bg,
-				       guint mmax)
-{
-  GtsEHeap * h1, * h2;
-  GtsGNode * n;
-  guint nm = 0, i;
-  GtsGNode ** moves;
-  gdouble bestcost = 0., totalcost = 0., best_balance;
-
-  g_return_val_if_fail (bg != NULL, 0.);
-  g_return_val_if_fail (mmax > 0, 0.);
-
-  h1 = gts_eheap_new ((GtsKeyFunc) node_move_cost1, bg);
-  gts_eheap_freeze (h1);
-  gts_container_foreach (GTS_CONTAINER (bg->g1), (GtsFunc) build_heap, h1);
-  gts_eheap_thaw (h1);
-
-  h2 = gts_eheap_new ((GtsKeyFunc) node_move_cost2, bg);
-  gts_eheap_freeze (h2);
-  gts_container_foreach (GTS_CONTAINER (bg->g2), (GtsFunc) build_heap, h2);
-  gts_eheap_thaw (h2);
-
-  moves = g_malloc (sizeof (GtsGNode *)*mmax);
-  best_balance = fabs (gts_graph_weight (bg->g1) - gts_graph_weight (bg->g2));
-
-  do {
-    GtsGraph * g1, * g2;
-    gdouble cost;
-
-    if (gts_graph_weight (bg->g1) > gts_graph_weight (bg->g2)) {
-      n = gts_eheap_remove_top (h1, &cost);
-      g1 = bg->g1;
-      g2 = bg->g2;
-    }
-    else {
-      n = gts_eheap_remove_top (h2, &cost);
-      g1 = bg->g2;
-      g2 = bg->g1;
-    }
-    if (n) {
-      GSList * i;
-
-      GTS_OBJECT (n)->reserved = NULL;
-      gts_container_add (GTS_CONTAINER (g2), GTS_CONTAINEE (n));
-      gts_container_remove (GTS_CONTAINER (g1), GTS_CONTAINEE (n));
-
-      totalcost += cost;
-      if (totalcost < bestcost) {
-	bestcost = totalcost;
-	nm = 0;
-      }
-      else if (totalcost == bestcost) {
-	gdouble balance = fabs (gts_graph_weight (g1) - gts_graph_weight (g2));
-
-	if (balance < best_balance) {
-	  best_balance = balance;
-	  nm = 0;
-	}
-      }	       
-      else
-	moves[nm++] = n;
-
-      i = GTS_SLIST_CONTAINER (n)->items;
-      while (i) {
-	GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
-	if (GTS_OBJECT (n1)->reserved && 
-	    gts_containee_is_contained (GTS_CONTAINEE (n1), 
-					GTS_CONTAINER (bg->g))) {
-	  GtsEHeap * h = 
-	    gts_containee_is_contained (GTS_CONTAINEE (n1), 
-					GTS_CONTAINER (bg->g1)) ? h1 : h2;
-	  gts_eheap_remove (h, GTS_OBJECT (n1)->reserved);
-	  GTS_OBJECT (n1)->reserved = gts_eheap_insert (h, n1);
-	}
-	i = i->next;
-      }
-    }
-  } while (n && nm < mmax);
-
-  gts_eheap_foreach (h1, (GFunc) gts_object_reset_reserved, NULL);
-  gts_eheap_foreach (h2, (GFunc) gts_object_reset_reserved, NULL);
-  gts_eheap_destroy (h1);
-  gts_eheap_destroy (h2);
-
-  /* undo last nm moves */
-  for (i = 0; i < nm; i++) {
-    GtsGNode * n = moves[i];
-    GtsGraph * g1 = 
-      gts_containee_is_contained (GTS_CONTAINEE (n),
-				  GTS_CONTAINER (bg->g1)) ? bg->g1 : bg->g2;
-    GtsGraph * g2 = g1 == bg->g1 ? bg->g2 : bg->g1;
-    
-    gts_container_add (GTS_CONTAINER (g2), GTS_CONTAINEE (n));
-    gts_container_remove (GTS_CONTAINER (g1), GTS_CONTAINEE (n));
-  }
-  g_free (moves);
-
-  return bestcost;
-}
-
-static void build_bheap (GtsGNode * n, GtsGNode * n1, GtsEHeap * heap)
-{
-  GTS_OBJECT (n)->reserved = gts_eheap_insert (heap, n);
-}
-
-static void update_neighbors (GtsGNode * n, GtsGraphBisection * bg,
-			      GtsEHeap * h1, GtsEHeap * h2)
-{
-  GSList * i;
-
-  i = GTS_SLIST_CONTAINER (n)->items;
-  while (i) {
-    GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
-    if (gts_containee_is_contained (GTS_CONTAINEE (n1), 
-				    GTS_CONTAINER (bg->g))) {
-      GtsEHeap * h;
-      GtsGraph * g1, * g2;
-      GHashTable * bg1;
-
-      if (gts_containee_is_contained (GTS_CONTAINEE (n1),
-				      GTS_CONTAINER (bg->g1))) {
-	h = h1;
-	g1 = bg->g1;
-	g2 = bg->g2;
-	bg1 = bg->bg1;
-      }
-      else {
-	h = h2;
-	g1 = bg->g2;
-	g2 = bg->g1;
-	bg1 = bg->bg2;
-      }
-      g_hash_table_remove (bg1, n1);
-      if (h && GTS_OBJECT (n1)->reserved && GTS_OBJECT (n1)->reserved != n1) {
-	gts_eheap_remove (h, GTS_OBJECT (n1)->reserved);
-	GTS_OBJECT (n1)->reserved = NULL;
-      }
-      if (gts_gnode_degree (n1, g2)) {
-	g_hash_table_insert (bg1, n1, n1);
-	if (h && GTS_OBJECT (n1)->reserved != n1)
-	  GTS_OBJECT (n1)->reserved = gts_eheap_insert (h, n1);
-      }
-    }
-    i = i->next;
-  }  
-}
-
-/**
- * gts_graph_bisection_bkl_refine:
- * @bg: a #GtsGraphBisection.
- * @mmax: the maximum number of unsuccessful successive moves.
- * @imbalance: the maximum relative imbalance allowed between the
- * weights of both halves of the partition.
- *
- * An implementation of the simplified boundary Kernighan-Lin
- * algorithm for graph bisection refinement as described in Karypis
- * and Kumar (1997).
- *
- * The algorithm stops if @mmax consecutive modes do not lead to a
- * decrease in the number of edges cut. This last @mmax moves are
- * undone.
- *
- * Returns: the decrease in the weight of the edges cut by the bisection.  
- */
-gdouble gts_graph_bisection_bkl_refine (GtsGraphBisection * bg,
-					guint mmax,
-					gfloat imbalance)
-{
-  GtsEHeap * h1, * h2;
-  GtsGNode * n;
-  guint nm = 0, i;
-  GtsGNode ** moves;
-  gdouble bestcost = 0., totalcost = 0., best_balance;
-  gboolean balanced = FALSE;
-
-  g_return_val_if_fail (bg != NULL, 0.);
-  g_return_val_if_fail (mmax > 0, 0.);
-  g_return_val_if_fail (imbalance >= 0. && imbalance <= 1., 0.);
-
-  h1 = gts_eheap_new ((GtsKeyFunc) node_move_cost1, bg);
-  gts_eheap_freeze (h1);
-  g_hash_table_foreach (bg->bg1, (GHFunc) build_bheap, h1);
-  gts_eheap_thaw (h1);
-
-  h2 = gts_eheap_new ((GtsKeyFunc) node_move_cost2, bg);
-  gts_eheap_freeze (h2);
-  g_hash_table_foreach (bg->bg2, (GHFunc) build_bheap, h2);
-  gts_eheap_thaw (h2);
-
-  moves = g_malloc (sizeof (GtsGNode *)*mmax);
-  imbalance *= gts_graph_weight (bg->g);
-  best_balance = fabs (gts_graph_weight (bg->g1) - gts_graph_weight (bg->g2));
-  if (best_balance <= imbalance)
-    balanced = TRUE;
-
-  do {
-    GtsGraph * g1, * g2;
-    GHashTable * bg1, * bg2;
-    gdouble cost;
-
-    if (gts_graph_weight (bg->g1) > gts_graph_weight (bg->g2)) {
-      n = gts_eheap_remove_top (h1, &cost);
-      g1 = bg->g1;
-      g2 = bg->g2;
-      bg1 = bg->bg1;
-      bg2 = bg->bg2;
-    }
-    else {
-      n = gts_eheap_remove_top (h2, &cost);
-      g1 = bg->g2;
-      g2 = bg->g1;
-      bg1 = bg->bg2;
-      bg2 = bg->bg1;
-    }
-    if (n) {
-      gdouble balance;
-	
-      GTS_OBJECT (n)->reserved = n;
-      gts_container_add (GTS_CONTAINER (g2), GTS_CONTAINEE (n));
-      gts_container_remove (GTS_CONTAINER (g1), GTS_CONTAINEE (n));
-      g_hash_table_remove (bg1, n);
-      if (gts_gnode_degree (n, g1))
-	g_hash_table_insert (bg2, n, n);
-
-      update_neighbors (n, bg, h1, h2);
-
-      totalcost += cost;
-      balance = fabs (gts_graph_weight (g1) - gts_graph_weight (g2));
-      
-      if (!balanced && balance <= imbalance) {
-	bestcost = totalcost;
-	best_balance = balance;
-	balanced = TRUE;
-	nm = 0;
-      }
-      else if (totalcost < bestcost && 
-	       (balance < best_balance || balance <= imbalance)) {
-	bestcost = totalcost;
-	best_balance = balance;
-	nm = 0;
-      }
-      else if (totalcost == bestcost && balance < best_balance) {
-	best_balance = balance;
-	nm = 0;
-      }
-      else
-	moves[nm++] = n;
-    }
-  } while (n && nm < mmax);
-
-  gts_container_foreach (GTS_CONTAINER (bg->g), 
-			 (GtsFunc) gts_object_reset_reserved, NULL);
-  gts_eheap_destroy (h1);
-  gts_eheap_destroy (h2);
-
-  /* undo last nm moves */
-  for (i = 0; i < nm; i++) {
-    GtsGNode * n = moves[i];
-    GtsGraph * g1, * g2;
-    GHashTable * bg1, * bg2;
-
-    if (gts_containee_is_contained (GTS_CONTAINEE (n),
-				    GTS_CONTAINER (bg->g1))) {
-      g1 = bg->g1;
-      g2 = bg->g2;
-      bg1 = bg->bg1;
-      bg2 = bg->bg2;
-    }
-    else {
-      g1 = bg->g2;
-      g2 = bg->g1;
-      bg1 = bg->bg2;
-      bg2 = bg->bg1;
-    }
-    
-    gts_container_add (GTS_CONTAINER (g2), GTS_CONTAINEE (n));
-    gts_container_remove (GTS_CONTAINER (g1), GTS_CONTAINEE (n));
-    g_hash_table_remove (bg1, n);
-    if (gts_gnode_degree (n, g1))
-      g_hash_table_insert (bg2, n, n);
-
-    update_neighbors (n, bg, NULL, NULL);
-  }
-  g_free (moves);
-
-  return bestcost;
-}
-
-/* Multilevel partitioning */
-
-static void bisection_children (GtsGNodeSplit * ns, GtsGraphBisection * bg)
-{
-  GtsGraph * g, * g1;
-  GHashTable * bbg;
-  GtsGNode * n1 = GTS_GNODE_SPLIT_N1 (ns);
-  GtsGNode * n2 = GTS_GNODE_SPLIT_N2 (ns);
-
-  if (gts_containee_is_contained (GTS_CONTAINEE (ns->n),
-				  GTS_CONTAINER (bg->g1))) {
-    g = bg->g1;
-    g1 = bg->g2;
-    bbg = bg->bg1;
-  }
-  else {
-    g = bg->g2;
-    g1 = bg->g1;
-    bbg = bg->bg2;
-  }
-
-  gts_allow_floating_gnodes = TRUE;
-  gts_container_remove (GTS_CONTAINER (g), GTS_CONTAINEE (ns->n));
-  gts_allow_floating_gnodes = FALSE;
-  gts_container_add (GTS_CONTAINER (g), GTS_CONTAINEE (n1));
-  gts_container_add (GTS_CONTAINER (g), GTS_CONTAINEE (n2));
-
-  if (g_hash_table_lookup (bbg, ns->n)) {
-    g_hash_table_remove (bbg, ns->n);
-    if (gts_gnode_degree (n1, g1) > 0)
-      g_hash_table_insert (bbg, n1, n1);
-    if (gts_gnode_degree (n2, g1) > 0)
-      g_hash_table_insert (bbg, n2, n2);
-  }
-}
-
-/**
- * gts_graph_bisection_new:
- * @wg: a #GtsWGraph.
- * @ntry: the number of tries for the graph growing algorithm.
- * @mmax: the number of unsucessful moves for the refinement algorithm.
- * @nmin: the minimum number of nodes of the coarsest graph.
- * @imbalance: the maximum relative imbalance allowed between the
- * weights of both halves of the partition.
- *
- * An implementation of a multilevel bisection algorithm as presented
- * in Karypis and Kumar (1997). A multilevel hierarchy of graphs is
- * created using the #GtsPGraph object. The bisection of the coarsest
- * graph is created using the gts_graph_ggg_bisection() function. The
- * graph is then uncoarsened using gts_pgraph_down() and at each level
- * the bisection is refined using gts_graph_bisection_bkl_refine().
- *
- * Returns: a new #GtsGraphBisection of @wg.  
- */
-GtsGraphBisection * gts_graph_bisection_new (GtsWGraph * wg,
-					     guint ntry,
-					     guint mmax,
-					     guint nmin,
-					     gfloat imbalance)
-{
-  GtsGraph * g;
-  GtsPGraph * pg;
-  GtsGraphBisection * bg;
-  gdouble cost;
-
-  g_return_val_if_fail (wg != NULL, NULL);
-
-  g = GTS_GRAPH (wg);
-  pg = gts_pgraph_new (gts_pgraph_class (), g, 
-		       gts_gnode_split_class (),
-		       gts_wgnode_class (),
-		       gts_wgedge_class (),
-		       nmin);
-
-  bg = gts_graph_ggg_bisection (g, ntry);
-#ifdef DEBUG
-  fprintf (stderr, "before size: %5d weight: %5g cuts: %5d cweight: %5g\n",
-	   gts_container_size (GTS_CONTAINER (bg->g1)),
-	   gts_graph_weight (bg->g1),
-	   gts_graph_edges_cut (bg->g1),
-	   gts_graph_edges_cut_weight (bg->g1));
-  g_assert (gts_graph_bisection_check (bg));
-#endif
-  while ((cost = gts_graph_bisection_bkl_refine (bg, mmax, imbalance))) {
-#ifdef DEBUG
-    fprintf (stderr, "  cost: %g\n", cost);
-    g_assert (gts_graph_bisection_check (bg));
-#endif
-  }
-#ifdef DEBUG
-  fprintf (stderr, "after  size: %5d weight: %5g cuts: %5d cweight: %5g\n",
-	   gts_container_size (GTS_CONTAINER (bg->g1)),
-	   gts_graph_weight (bg->g1),
-	   gts_graph_edges_cut (bg->g1),
-	   gts_graph_edges_cut_weight (bg->g1));
-#endif
-  while (gts_pgraph_down (pg, (GtsFunc) bisection_children, bg)) {
-#ifdef DEBUG
-    fprintf (stderr, "before size: %5d weight: %5g cuts: %5d cweight: %5g\n",
-	     gts_container_size (GTS_CONTAINER (bg->g1)),
-	     gts_graph_weight (bg->g1),
-	     gts_graph_edges_cut (bg->g1),
-	     gts_graph_edges_cut_weight (bg->g1));	   
-#endif
-    while ((cost = gts_graph_bisection_bkl_refine (bg, mmax, imbalance))) {
-#ifdef DEBUG
-      fprintf (stderr, "  cost: %g\n", cost);
-      g_assert (gts_graph_bisection_check (bg));
-#endif
-    }
-#ifdef DEBUG
-    fprintf (stderr, "after  size: %5d weight: %5g cuts: %5d cweight: %5g\n",
-	     gts_container_size (GTS_CONTAINER (bg->g1)),
-	     gts_graph_weight (bg->g1),
-	     gts_graph_edges_cut (bg->g1),
-	     gts_graph_edges_cut_weight (bg->g1));
-#endif
-  }
-  gts_object_destroy (GTS_OBJECT (pg));
-
-  return bg;
-}
-
-/**
- * gts_graph_bisection_destroy:
- * @bg: a #GtsGraphBisection.
- * @destroy_graphs: controls graph destruction.
- *
- * Frees all the memory allocated for @bg. If @destroy_graphs is %TRUE
- * the graphs created by @bg are destroyed.  
- */
-void gts_graph_bisection_destroy (GtsGraphBisection * bg,
-				  gboolean destroy_graphs)
-{
-  g_return_if_fail (bg != NULL);
-
-  g_hash_table_destroy (bg->bg1);
-  g_hash_table_destroy (bg->bg2);
-
-  if (destroy_graphs) {
-    gts_object_destroy (GTS_OBJECT (bg->g1));
-    gts_object_destroy (GTS_OBJECT (bg->g2));
-  }
-
-  g_free (bg);
-}
-
-static void recursive_bisection (GtsWGraph * wg,
-				 guint np,
-				 guint ntry,
-				 guint mmax,
-				 guint nmin,
-				 gfloat imbalance,
-				 GSList ** list)
-{
-  if (np == 0)
-    *list = g_slist_prepend (*list, wg);
-  else {
-    GtsGraphBisection * bg = 
-      gts_graph_bisection_new (wg, ntry, mmax, nmin, imbalance);
-    GtsGraph * g1 = bg->g1;
-    GtsGraph * g2 = bg->g2;
-
-    gts_object_destroy (GTS_OBJECT (wg));
-    gts_graph_bisection_destroy (bg, FALSE);
-    recursive_bisection (GTS_WGRAPH (g1), np - 1, ntry, mmax, nmin, imbalance,
-			 list);
-    recursive_bisection (GTS_WGRAPH (g2), np - 1, ntry, mmax, nmin, imbalance,
-			 list);
-  }
-}
-
-/**
- * gts_graph_recursive_bisection:
- * @wg: a #GtsWGraph.
- * @n: the number of bisection levels.
- * @ntry: the number of tries for the graph growing algorithm.
- * @mmax: the number of unsucessful moves for the refinement algorithm.
- * @nmin: the minimum number of nodes of the coarsest graph.
- * @imbalance: the maximum relative imbalance allowed between the
- * weights of both halves of the partition.
- *
- * Calls gts_graph_bisection_new() recursively in order to obtain a
- * 2^@n partition of @wg.
- *
- * Returns: a list of 2^@n new #GtsGraph representing the partition.
- */
-GSList * gts_graph_recursive_bisection (GtsWGraph * wg,
-					guint n,
-					guint ntry,
-					guint mmax,
-					guint nmin,
-					gfloat imbalance)
-{
-  GtsGraphBisection * bg;
-  GtsGraph * g1, * g2;
-  GSList * list = NULL;
-
-  g_return_val_if_fail (wg != NULL, NULL);
-  g_return_val_if_fail (n > 0, NULL);
-  
-  bg = gts_graph_bisection_new (wg, ntry, mmax, nmin, imbalance);
-  g1 = bg->g1;
-  g2 = bg->g2;
-  gts_graph_bisection_destroy (bg, FALSE);
-  recursive_bisection (GTS_WGRAPH (g1), n - 1, ntry, mmax, nmin, imbalance, 
-		       &list);
-  recursive_bisection (GTS_WGRAPH (g2), n - 1, ntry, mmax, nmin, imbalance,
-		       &list);
-
-  return list;
-}
diff --git a/src/gts/pgraph.c b/src/gts/pgraph.c
deleted file mode 100644
index 6d1f619..0000000
--- a/src/gts/pgraph.c
+++ /dev/null
@@ -1,584 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include "gts.h"
-
-/* GtsGNodeSplit */
-
-static void gnode_split_destroy (GtsObject * object)
-{
-  GtsGNodeSplit * ns = GTS_GNODE_SPLIT (object);
-
-  if (gts_container_size (GTS_CONTAINER (ns->n)) == 0) {
-    g_assert (GTS_SLIST_CONTAINEE (ns->n)->containers == NULL);
-    gts_object_destroy (GTS_OBJECT (ns->n));
-  }
-  else {
-    /* GtsGNode * n1 = GTS_GNODE_SPLIT_N1 (ns); */
-    /* GtsGNode * n2 = GTS_GNODE_SPLIT_N2 (ns); */
-
-    g_warning ("Memory deallocation for GtsGNodeSplit not fully implemented yet: memory leak!");
-  }
-
-  (* GTS_OBJECT_CLASS (gts_gnode_split_class ())->parent_class->destroy) 
-    (object);
-}
-
-static void gnode_split_class_init (GtsGNodeSplitClass * klass)
-{
-  GTS_OBJECT_CLASS (klass)->destroy = gnode_split_destroy;
-}
-
-static void gnode_split_init (GtsGNodeSplit * ns)
-{
-  ns->n = NULL;
-  ns->n1 = ns->n2 = NULL;
-}
-
-/**
- * gts_gnode_split_class:
- *
- * Returns: the #GtsGNodeSplitClass.
- */
-GtsGNodeSplitClass * gts_gnode_split_class (void)
-{
-  static GtsGNodeSplitClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo gnode_split_info = {
-      "GtsGNodeSplit",
-      sizeof (GtsGNodeSplit),
-      sizeof (GtsGNodeSplitClass),
-      (GtsObjectClassInitFunc) gnode_split_class_init,
-      (GtsObjectInitFunc) gnode_split_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (gts_object_class (), &gnode_split_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_gnode_split_new:
- * @klass: a #GtsGNodeSplitClass.
- * @n: a #GtsGNode.
- * @n1: a #GtsGNodeSplit or #GtsGNode.
- * @n2: a #GtsGNodeSplit or #GtsGNode.
- *
- * Creates a new #GtsGNodeSplit which would collapse @n1 and @n2 into
- * @n. The collapse itself is not performed.
- *
- * Returns: the new #GtsGNodeSplit.
- */
-GtsGNodeSplit * gts_gnode_split_new (GtsGNodeSplitClass * klass,
-				     GtsGNode * n, 
-				     GtsObject * n1,
-				     GtsObject * n2)
-{
-  GtsGNodeSplit * ns;
-
-  g_return_val_if_fail (klass != NULL, NULL);
-  g_return_val_if_fail (n != NULL, NULL);
-  g_return_val_if_fail (GTS_IS_GNODE_SPLIT (n1) || GTS_IS_GNODE (n1), NULL);
-  g_return_val_if_fail (GTS_IS_GNODE_SPLIT (n2) || GTS_IS_GNODE (n2), NULL);
-
-  ns = GTS_GNODE_SPLIT (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  ns->n = n;
-  ns->n1 = n1;
-  ns->n2 = n2;
-
-  return ns;
-}
-
-static void connect_edge (GtsGEdge * e, gpointer * data)
-{
-  GtsGNode * n = data[0];
-  GtsGNode * n1 = data[1];
-  GtsGNode * n2 = data[2];
-
-  if (GTS_OBJECT (e)->reserved || /* edge is disconnected */
-      gts_gedge_connects (e, n1, n2))
-    return;
-  if (e->n1 == n1 || e->n1 == n2)
-    e->n1 = n;
-  else if (e->n2 == n1 || e->n2 == n2)
-    e->n2 = n;
-  else
-    g_assert_not_reached ();
-  gts_container_add (GTS_CONTAINER (n), GTS_CONTAINEE (e));
-}
-
-/**
- * gts_gnode_split_collapse:
- * @ns: a #GtsGNodeSplit.
- * @g: a #GtsGraph.
- * @klass: a #GtsWGEdgeClass.
- *
- * Collapses the node split @ns. Any new edge created during the
- * process will be of class @klass.  
- */
-void gts_gnode_split_collapse (GtsGNodeSplit * ns,
-			       GtsGraph * g,
-			       GtsWGEdgeClass * klass)
-{
-  GtsGNode * n1, * n2;
-  GSList * i;
-  gpointer data[3];
-
-  g_return_if_fail (ns != NULL);
-  g_return_if_fail (g != NULL);
-  g_return_if_fail (gts_container_size (GTS_CONTAINER (ns->n)) == 0);
-
-  n1 = GTS_GNODE_SPLIT_N1 (ns);
-  n2 = GTS_GNODE_SPLIT_N2 (ns);
-
-  /* look for triangles */
-  i = GTS_SLIST_CONTAINER (n1)->items;
-  while (i) {
-    GtsGEdge * e13 = i->data;
-    GtsGNode * n3 = GTS_GNODE_NEIGHBOR (n1, e13);
-    if (n3 != n2) {
-      GSList * j = GTS_SLIST_CONTAINER (n3)->items;
-      while (j) {
-	GtsGEdge * e32 = j->data;
-	GSList * next = j->next;
-	GtsGNode * n4 = GTS_GNODE_NEIGHBOR (n3, e32);
-	if (n4 == n2) { /* found triangle n1 (e13) n3 (e32) n2 */
-	  gts_wgedge_new (klass, ns->n, n3,
-			  gts_gedge_weight (e13) + gts_gedge_weight (e32));
-	  GTS_OBJECT (e13)->reserved = n3;
-	  GTS_OBJECT (e32)->reserved = n3;
-	  GTS_SLIST_CONTAINER (n3)->items = 
-	    g_slist_remove (GTS_SLIST_CONTAINER (n3)->items, e32);
-	}
-	j = next;
-      }
-      if (GTS_OBJECT (e13)->reserved == n3)
-	GTS_SLIST_CONTAINER (n3)->items = 
-	  g_slist_remove (GTS_SLIST_CONTAINER (n3)->items, e13);
-    }
-    i = i->next;
-  }
-
-  /* connect edges to new node */
-  data[0] = ns->n;
-  data[1] = n1;
-  data[2] = n2;
-  gts_container_foreach (GTS_CONTAINER (n1), (GtsFunc) connect_edge, data);
-  gts_container_foreach (GTS_CONTAINER (n2), (GtsFunc) connect_edge, data);
-
-  gts_allow_floating_gnodes = TRUE;
-  gts_container_remove (GTS_CONTAINER (g), GTS_CONTAINEE (n1));
-  gts_container_remove (GTS_CONTAINER (g), GTS_CONTAINEE (n2));
-  gts_allow_floating_gnodes = FALSE;
-  gts_container_add (GTS_CONTAINER (g), GTS_CONTAINEE (ns->n));
-}
-
-static void restore_edge (GtsGEdge * e, gpointer * data)
-{
-  GtsGNode * n = data[0];
-  GtsGNode * n1 = data[1];
-  GtsGNode * n2 = data[2];
-  GtsGNode * n3 = GTS_OBJECT (e)->reserved;
-
-  if (n3) { /* e is a disconnected edge */
-    GTS_OBJECT (e)->reserved = NULL;
-    gts_container_add (GTS_CONTAINER (n3), GTS_CONTAINEE (e));
-    return;
-  }
-
-  if (gts_gedge_connects (e, n1, n2))
-    return;
-
-  if (e->n1 == n)
-    e->n1 = n1;
-  else if (e->n2 == n)
-    e->n2 = n1;
-  else
-    g_assert_not_reached ();
-  GTS_SLIST_CONTAINER (n)->items = 
-    g_slist_remove (GTS_SLIST_CONTAINER (n)->items, e);
-}
-
-/**
- * gts_gnode_split_expand:
- * @ns: a #GtsGNodeSplit.
- * @g: a #GtsGraph.
- *
- * Expands the node split ns adding the new nodes to @g.
- */
-void gts_gnode_split_expand (GtsGNodeSplit * ns,
-			     GtsGraph * g)
-{
-  GtsGNode * n1, * n2;
-  gpointer data[3];
-  GSList * i;
-
-  g_return_if_fail (ns != NULL);
-  g_return_if_fail (g != NULL);
-  g_return_if_fail (gts_containee_is_contained (GTS_CONTAINEE (ns->n), 
-						GTS_CONTAINER (g)));
-
-  n1 = GTS_GNODE_SPLIT_N1 (ns);
-  n2 = GTS_GNODE_SPLIT_N2 (ns);
-
-  data[0] = ns->n;
-  data[1] = n1;
-  data[2] = n2;
-  gts_container_foreach (GTS_CONTAINER (n1), (GtsFunc) restore_edge, data);
-  data[1] = n2;
-  data[2] = n1;
-  gts_container_foreach (GTS_CONTAINER (n2), (GtsFunc) restore_edge, data);
-
-  i = GTS_SLIST_CONTAINER (ns->n)->items;
-  while (i) {
-    GSList * next = i->next;
-    gts_container_remove (GTS_CONTAINER (ns->n), GTS_CONTAINEE (i->data));
-    i = next;
-  }
-  g_assert (gts_container_size (GTS_CONTAINER (ns->n)) == 0);
-  
-  gts_allow_floating_gnodes = TRUE;
-  gts_container_remove (GTS_CONTAINER (g), GTS_CONTAINEE (ns->n));
-  gts_allow_floating_gnodes = FALSE;
-
-  gts_container_add (GTS_CONTAINER (g), GTS_CONTAINEE (n1));
-  gts_container_add (GTS_CONTAINER (g), GTS_CONTAINEE (n2));
-}
-
-/* GtsPGraph */
-
-static void pgraph_destroy (GtsObject * object)
-{
-  GtsPGraph * pg = GTS_PGRAPH (object);
-  guint i;
-
-  for (i = 0; i < pg->split->len; i++)
-    gts_object_destroy (GTS_OBJECT (g_ptr_array_index (pg->split, i)));
-  g_ptr_array_free (pg->split, TRUE);
-  g_array_free (pg->levels, TRUE);
-
-  (* GTS_OBJECT_CLASS (gts_pgraph_class ())->parent_class->destroy) (object);
-}
-
-static void pgraph_class_init (GtsPGraphClass * klass)
-{
-  GTS_OBJECT_CLASS (klass)->destroy = pgraph_destroy;
-}
-
-static void pgraph_init (GtsPGraph * pg)
-{
-  pg->g = NULL;
-  pg->split = g_ptr_array_new ();
-  pg->levels = g_array_new (FALSE, FALSE, sizeof (guint));
-  pg->level = 0;
-  pg->split_class = gts_gnode_split_class ();
-  pg->edge_class = gts_wgedge_class ();
-  pg->pos = pg->min = 0;
-}
-
-/**
- * gts_pgraph_class:
- *
- * Returns: the #GtsPGraphClass.
- */
-GtsPGraphClass * gts_pgraph_class (void)
-{
-  static GtsPGraphClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo pgraph_info = {
-      "GtsPGraph",
-      sizeof (GtsPGraph),
-      sizeof (GtsPGraphClass),
-      (GtsObjectClassInitFunc) pgraph_class_init,
-      (GtsObjectInitFunc) pgraph_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (gts_object_class (), &pgraph_info);
-  }
-
-  return klass;
-}
-
-static void match_neighbor (GtsGNode * n, gpointer * data)
-{
-  if (!GTS_OBJECT (n)->reserved) {
-    GtsGraph * g = data[0];
-    GSList ** list = data[1];
-    GSList * i = GTS_SLIST_CONTAINER (n)->items;
-    gfloat wmax = - G_MAXFLOAT;
-    GtsGEdge * emax = NULL;
-    
-    while (i) {
-      GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, i->data);
-      if (!GTS_OBJECT (n1)->reserved &&
-	  gts_gedge_weight (i->data) > wmax &&
-	  gts_containee_is_contained (GTS_CONTAINEE (n1), GTS_CONTAINER (g))) {
-	emax = i->data;
-	wmax = gts_gedge_weight (emax);
-      }
-      i = i->next;
-    }
-    if (emax) {
-      GtsGNode * n1 = GTS_GNODE_NEIGHBOR (n, emax);
-
-      GTS_OBJECT (n1)->reserved = n;
-      GTS_OBJECT (n)->reserved = n1;
-      *list = g_slist_prepend (*list, emax);
-    }
-  }
-}
-
-static GSList * maximal_matching (GtsGraph * g)
-{
-  GSList * list = NULL;
-  gpointer data[2];
-
-  data[0] = g;
-  data[1] = &list;
-  gts_container_foreach (GTS_CONTAINER (g), (GtsFunc) match_neighbor, data);
-  gts_container_foreach (GTS_CONTAINER (g), 
-			 (GtsFunc) gts_object_reset_reserved,
-			 NULL);
-
-  return list;
-}
-
-/**
- * gts_pgraph_new:
- * @klass: a #GtsPGraphClass.
- * @g: a #GtsGraph.
- * @split_class: a #GtsGNodeSplitClass.
- * @node_class: a #GtsWGNodeClass.
- * @edge_class: a #GtsWGEdgeClass.
- * @min: the minimum number of nodes.
- *
- * Creates a new multilevel approximation of graph @g. At each level a
- * maximal matching is created using the Heavy Edge Matching (HEM)
- * technique of Karypis and Kumar (1997). The newly created nodes are
- * of type @node_class and their weight is set to the sum of the
- * weights of their children. The newly created edges are of type
- * @edge_class and their weight is set to the sum of the weight of the
- * collapsed edges. The last level is reached when the maximal
- * matching obtained would lead to a graph with less than @min nodes.
- *
- * Returns: the new #GtsPGraph containing the multilevel
- * representation of @g.  
- */
-GtsPGraph * gts_pgraph_new (GtsPGraphClass * klass,
-			    GtsGraph * g,
-			    GtsGNodeSplitClass * split_class,
-			    GtsWGNodeClass * node_class,
-			    GtsWGEdgeClass * edge_class,
-			    guint min)
-{
-  GtsPGraph * pg;
-  GSList * matching;
-
-  g_return_val_if_fail (klass != NULL, NULL);
-  g_return_val_if_fail (g != NULL, NULL);
-  g_return_val_if_fail (split_class != NULL, NULL);
-  g_return_val_if_fail (node_class != NULL, NULL);
-  g_return_val_if_fail (edge_class != NULL, NULL);
-
-  pg = GTS_PGRAPH (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  pg->g = g;
-  pg->split_class = split_class;
-  pg->edge_class = edge_class;
-
-  while (gts_container_size (GTS_CONTAINER (g)) > min &&
-	 (matching = maximal_matching (g))) {
-    GSList * i = matching;
-    guint size = gts_container_size (GTS_CONTAINER (g));
-
-    g_array_append_val (pg->levels, size);
-
-    while (i && gts_container_size (GTS_CONTAINER (g)) > min) {
-      GtsGEdge * e = i->data;
-      GtsGNode * n = GTS_GNODE (gts_wgnode_new (node_class,
-						gts_gnode_weight (e->n1) +
-						gts_gnode_weight (e->n2)));
-      GtsGNodeSplit * ns = gts_gnode_split_new (split_class, n,
-						GTS_OBJECT (e->n1),
-						GTS_OBJECT (e->n2));
-      gts_gnode_split_collapse (ns, g, edge_class);
-      g_ptr_array_add (pg->split, ns);
-      i = i->next;
-    }
-    g_slist_free (matching);
-  }
-
-  pg->pos = pg->split->len;
-  pg->min = gts_container_size (GTS_CONTAINER (g));
-  pg->level = pg->levels->len;
-  
-  return pg;
-}
-
-/**
- * gts_pgraph_add_node:
- * @pg: a #GtsPGraph.
- *
- * Adds one node to the multilevel graph @pg by expanding the next
- * available #GtsGNodeSplit.
- *
- * Returns: the expanded #GtsGNodeSplit or #NULL if all the
- * #GtsGNodeSplit have already been expanded.  
- */
-GtsGNodeSplit * gts_pgraph_add_node (GtsPGraph * pg)
-{ 
-  GtsGNodeSplit * ns;
-
-  g_return_val_if_fail (pg != NULL, NULL);
-
-  if (pg->pos == 0)
-    return NULL;
-
-  ns = g_ptr_array_index (pg->split, --pg->pos);
-  gts_gnode_split_expand (ns, pg->g);
-
-  return ns;
-}
-
-/**
- * gts_pgraph_remove_node:
- * @pg: a #GtsPGraph.
- *
- * Removes one node from the multilevel graph @pg by collapsing the
- * first available #GtsGNodeSplit.
- *
- * Returns: the collapsed #GtsGNodeSplit or %NULL if all the
- * #GtsGNodeSplit have already been collapsed.  
- */
-GtsGNodeSplit * gts_pgraph_remove_node (GtsPGraph * pg)
-{
-  GtsGNodeSplit * ns;
-
-  g_return_val_if_fail (pg != NULL, NULL);
-
-  if (pg->pos == pg->split->len)
-    return NULL;
-
-  ns = g_ptr_array_index (pg->split, pg->pos++);
-  gts_gnode_split_collapse (ns, pg->g, pg->edge_class);
-
-  return ns;
-}
-
-/**
- * gts_pgraph_max_node_number:
- * @pg: a #GtsPGraph.
- *
- * Returns: the maximum number of nodes of @pg i.e. the number of
- * nodes if all the #GtsGNodeSplit were expanded.  
- */
-guint gts_pgraph_max_node_number (GtsPGraph * pg)
-{
-  g_return_val_if_fail (pg != NULL, 0);
-
-  return pg->min + pg->split->len;
-}
-
-/**
- * gts_pgraph_min_node_number:
- * @pg: a #GtsPGraph.
- *
- * Returns: the minimum number of nodes of @pg i.e. the number of
- * nodes if all the #GtsGNodeSplit were collapsed.  
- */
-guint gts_pgraph_min_node_number (GtsPGraph * pg)
-{
-  g_return_val_if_fail (pg != NULL, 0);
-
-  return pg->min;
-}
-
-/**
- * gts_pgraph_set_node_number:
- * @pg: a #GtsPGraph.
- * @n: a number of nodes.
- *
- * Performs the required number of collapses or expansions to set the
- * number of nodes of @pg to @n.
- */
-void gts_pgraph_set_node_number (GtsPGraph * pg, guint n)
-{
-  g_return_if_fail (pg != NULL);
-
-  n = pg->min + pg->split->len - n;
-  while (pg->pos > n && gts_pgraph_add_node (pg))
-    ;
-  while (pg->pos < n && gts_pgraph_remove_node (pg))
-    ;
-}
-
-/**
- * gts_pgraph_get_node_number:
- * @pg: a #GtsPGraph.
- *
- * Returns: the current number of nodes of @pg.
- */
-guint gts_pgraph_get_node_number (GtsPGraph * pg)
-{
-  g_return_val_if_fail (pg != NULL, 0);
-  
-  return pg->min + pg->split->len - pg->pos;
-}
-
-/**
- * gts_pgraph_down:
- * @pg: a #GtsPGraph.
- * @func: a #GtsFunc or %NULL.
- * @data: user data to pass to @func.
- *
- * Performs the required number of expansions to go from the current
- * level to the level immediately below.
- *
- * If @func is not %NULL, it is called after each #GtsGNodeSplit has
- * been expanded.  
- *
- * Returns: %FALSE if it is not possible to go down one level, %TRUE
- * otherwise.  
- */
-gboolean gts_pgraph_down (GtsPGraph * pg,
-			  GtsFunc func,
-			  gpointer data)
-{
-  guint size;
-
-  g_return_val_if_fail (pg != NULL, FALSE);
-
-  if (pg->level == 0)
-    return FALSE;
-
-  size = g_array_index (pg->levels, guint, --(pg->level));
-  while (gts_container_size (GTS_CONTAINER (pg->g)) < size) {
-    GtsGNodeSplit * ns = gts_pgraph_add_node (pg);
-
-    g_assert (ns);
-    if (func)
-      (* func) (ns, data);
-  }
-  return TRUE;
-}
-
diff --git a/src/gts/point.c b/src/gts/point.c
deleted file mode 100644
index 42fce69..0000000
--- a/src/gts/point.c
+++ /dev/null
@@ -1,986 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <math.h>
-#include <stdlib.h>
-#include "gts.h"
-#include "gts-private.h"
-#include "predicates.h"
-
-static void point_read (GtsObject ** o, GtsFile * f)
-{
-  GtsPoint * p = GTS_POINT (*o);
-
-  if (GTS_POINT_CLASS ((*o)->klass)->binary) {
-    if (gts_file_read (f, &(p->x), sizeof (gdouble), 1) != 1) {
-      gts_file_error (f, "expecting a binary number (x coordinate)");
-      return;
-    }
-    if (gts_file_read (f, &(p->y), sizeof (gdouble), 1) != 1) {
-      gts_file_error (f, "expecting a binary number (y coordinate)");
-      return;
-    }
-    if (gts_file_read (f, &(p->z), sizeof (gdouble), 1) != 1) {
-      gts_file_error (f, "expecting a binary number (z coordinate)");
-      return;
-    }
-  }
-  else {
-    if (f->type != GTS_INT && f->type != GTS_FLOAT) {
-      gts_file_error (f, "expecting a number (x coordinate)");
-      return;
-    }
-    p->x = atof (f->token->str);
-    
-    gts_file_next_token (f);
-    if (f->type != GTS_INT && f->type != GTS_FLOAT) {
-      gts_file_error (f, "expecting a number (y coordinate)");
-      return;
-    }
-    p->y = atof (f->token->str);
-    
-    gts_file_next_token (f);
-    if (f->type != GTS_INT && f->type != GTS_FLOAT) {
-      gts_file_error (f, "expecting a number (z coordinate)");
-      return;
-    }
-    p->z = atof (f->token->str);
-    
-    gts_file_next_token (f);
-  }
-}
-
-static void point_write (GtsObject * o, FILE * fptr)
-{
-  GtsPoint * p = GTS_POINT (o);
-
-  if (GTS_POINT_CLASS ((o)->klass)->binary) {
-    fwrite (&(p->x), sizeof (gdouble), 1, fptr);
-    fwrite (&(p->y), sizeof (gdouble), 1, fptr);
-    fwrite (&(p->z), sizeof (gdouble), 1, fptr);
-  }
-  else
-    fprintf (fptr, "%.10g %.10g %.10g", p->x, p->y, p->z);
-}
-
-static void point_class_init (GtsObjectClass * klass)
-{
-  klass->read = point_read;
-  klass->write = point_write;
-}
-
-/**
- * gts_point_class:
- *
- * Returns: the #GtsPointClass.
- */
-GtsPointClass * gts_point_class (void)
-{
-  static GtsPointClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo point_info = {
-      "GtsPoint",
-      sizeof (GtsPoint),
-      sizeof (GtsPointClass),
-      (GtsObjectClassInitFunc) point_class_init,
-      (GtsObjectInitFunc) NULL,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (gts_object_class (), 
-				  &point_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_point_new:
- * @klass: a #GtsPointClass.
- * @x: the x-coordinate.
- * @y: the y-coordinate.
- * @z: the z-coordinate.
- *
- * Returns: a new #GtsPoint.
- */
-GtsPoint * gts_point_new (GtsPointClass * klass,
-			  gdouble x, gdouble y, gdouble z)
-{
-  GtsPoint * p;
-  
-  p = GTS_POINT (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  p->x = x;
-  p->y = y;
-  p->z = z;
-
-  return p;
-}
-
-/**
- * gts_point_set:
- * @p: a #GtsPoint.
- * @x: the x-coordinate.
- * @y: the y-coordinate.
- * @z: the z-coordinate.
- *
- * Sets the coordinates of @p.
- */
-void gts_point_set (GtsPoint * p, gdouble x, gdouble y, gdouble z)
-{
-  g_return_if_fail (p != NULL);
-
-  p->x = x;
-  p->y = y;
-  p->z = z;
-}
-
-/**
- * gts_point_distance:
- * @p1: a #GtsPoint.
- * @p2: another #GtsPoint.
- *
- * Returns: the Euclidean distance between @p1 and @p2.
- */
-gdouble gts_point_distance (GtsPoint * p1, GtsPoint * p2)
-{
-  g_return_val_if_fail (p1 != NULL && p2 != NULL, 0.0);
-  
-  return sqrt ((p1->x - p2->x)*(p1->x - p2->x) + 
-	       (p1->y - p2->y)*(p1->y - p2->y) + 
-	       (p1->z - p2->z)*(p1->z - p2->z));
-}
-
-/**
- * gts_point_distance2:
- * @p1: a #GtsPoint.
- * @p2: another #GtsPoint.
- *
- * Returns: the square of the Euclidean distance between @p1 and @p2.
- */
-gdouble gts_point_distance2 (GtsPoint * p1, GtsPoint * p2)
-{
-  g_return_val_if_fail (p1 != NULL && p2 != NULL, 0.0);
-  
-  return
-    (p1->x - p2->x)*(p1->x - p2->x) +
-    (p1->y - p2->y)*(p1->y - p2->y) + 
-    (p1->z - p2->z)*(p1->z - p2->z);
-}
-
-/**
- * gts_point_orientation_3d:
- * @p1: a #GtsPoint.
- * @p2: a #GtsPoint.
- * @p3: a #GtsPoint.
- * @p4: a #GtsPoint.
- *
- * Checks if @p4 lies above, below or on the plane passing through the
- * points @p1, @p2 and @p3. Below is defined so that @p1, @p2 and @p3
- * appear in counterclockwise order when viewed from above the
- * plane. The returned value is an approximation of six times the
- * signed volume of the tetrahedron defined by the four points. This
- * function uses adaptive floating point arithmetic and is
- * consequently geometrically robust.
- *
- * Returns: a positive value if @p4 lies below, a negative value if
- * @p4 lies above the plane, zero if the four points are coplanar.  
- */
-gdouble gts_point_orientation_3d (GtsPoint * p1,
-				  GtsPoint * p2,
-				  GtsPoint * p3,
-				  GtsPoint * p4)
-{
-  g_return_val_if_fail (p1 != NULL && p2 != NULL && 
-			p3 != NULL && p4 != NULL, 0.0);
-  return orient3d ((gdouble *) &p1->x, 
-		   (gdouble *) &p2->x, 
-		   (gdouble *) &p3->x, 
-		   (gdouble *) &p4->x);
-}
-
-/**
- * gts_point_is_in_triangle:
- * @p: a #GtsPoint.
- * @t: a #GtsTriangle.
- *
- * Tests if the planar projection (x, y) of @p is inside, outside or
- * on the boundary of the planar projection of @t.  This function is
- * geometrically robust.
- * 
- * Returns: %GTS_IN if @p is inside @t, %GTS_ON if @p is on the boundary of
- * @t, %GTS_OUT otherwise.  
- */
-GtsIntersect gts_point_is_in_triangle (GtsPoint * p, GtsTriangle * t)
-{
-  GtsVertex * v1, * v2, * v3;
-  gdouble d1, d2, d3;
-
-  g_return_val_if_fail (p != NULL && t != NULL, FALSE);
-
-  gts_triangle_vertices (t, &v1, &v2, &v3);
-
-  d1 = gts_point_orientation (GTS_POINT (v1), GTS_POINT (v2), p);
-  if (d1 < 0.0)
-    return GTS_OUT;
-  d2 = gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), p);
-  if (d2 < 0.0)
-    return GTS_OUT;
-  d3 = gts_point_orientation (GTS_POINT (v3), GTS_POINT (v1), p);
-  if (d3 < 0.0)
-    return GTS_OUT;
-  if (d1 == 0.0 || d2 == 0.0 || d3 == 0.0)
-    return GTS_ON;
-  return GTS_IN;
-}
-
-/**
- * gts_point_in_triangle_circle:
- * @p: a #GtsPoint.
- * @t: a #GtsTriangle.
- *
- * Tests if the planar projection (x, y) of @p is inside or outside
- * the circumcircle of the planar projection of @t. This function is
- * geometrically robust.
- * 
- * Returns: a positive number if @p lies inside,
- * a negative number if @p lies outside and zero if @p lies on 
- * the circumcircle of @t.  
- */
-gdouble gts_point_in_triangle_circle (GtsPoint * p, GtsTriangle * t)
-{
-  GtsPoint * p1, * p2, * p3;
-
-  g_return_val_if_fail (p != NULL && t != NULL, 0.0);
-
-  gts_triangle_vertices (t, 
-			 (GtsVertex **) &p1, 
-			 (GtsVertex **) &p2, 
-			 (GtsVertex **) &p3);
-
-  return incircle ((gdouble *) &p1->x, 
-		   (gdouble *) &p2->x, 
-		   (gdouble *) &p3->x, 
-		   (gdouble *) &p->x);
-}
-
-/**
- * gts_point_in_circle:
- * @p: a #GtsPoint.
- * @p1: a #GtsPoint.
- * @p2: a #GtsPoint.
- * @p3: a #GtsPoint.
- *
- * Tests if the planar projection (x, y) of @p is inside or outside the
- * circle defined by the planar projection of @p1, @p2 and @p3.
- * 
- * Returns: a positive number if @p lies inside,
- * a negative number if @p lies outside and zero if @p lies on 
- * the circle.
- */
-gdouble gts_point_in_circle (GtsPoint * p, 
-			     GtsPoint * p1, GtsPoint * p2, GtsPoint * p3)
-{
-  g_return_val_if_fail (p != NULL && p1 != NULL && p2 != NULL && p3 != NULL, 
-			0.0);
-
-  return incircle ((gdouble *) &p1->x, 
-		   (gdouble *) &p2->x, 
-		   (gdouble *) &p3->x, 
-		   (gdouble *) &p->x);
-}
-
-/**
- * gts_point_in_sphere:
- * @p: a #GtsPoint.
- * @p1: a #GtsPoint.
- * @p2: a #GtsPoint.
- * @p3: a #GtsPoint.
- * @p4: a #GtsPoint.
- *
- * Tests if @p is inside or outside the sphere defined by @p1, @p2,
- * @p3 and @p4.
- * 
- * Returns: a positive number if @p lies inside,
- * a negative number if @p lies outside and zero if @p lies on 
- * the sphere.
- */
-gdouble gts_point_in_sphere (GtsPoint * p, 
-			     GtsPoint * p1, GtsPoint * p2, GtsPoint * p3, GtsPoint * p4)
-{
-  g_return_val_if_fail (p != NULL && p1 != NULL && p2 != NULL && p3 != NULL && p4 != NULL, 
-			0.0);
-
-  return insphere ((gdouble *) &p1->x, 
-		   (gdouble *) &p2->x, 
-		   (gdouble *) &p3->x, 
-		   (gdouble *) &p4->x, 
-		   (gdouble *) &p->x);
-}
-
-/**
- * gts_point_segment_distance2:
- * @p: a #GtsPoint.
- * @s: a #GtsSegment.
- *
- * Returns: the square of the minimun Euclidean distance between @p and @s.
- */
-gdouble gts_point_segment_distance2 (GtsPoint * p, GtsSegment * s)
-{
-  gdouble t, ns2, x, y, z;
-  GtsPoint * p1, * p2;
-
-  g_return_val_if_fail (p != NULL, 0.0);
-  g_return_val_if_fail (s != NULL, 0.0);
-
-  p1 = GTS_POINT (s->v1);
-  p2 = GTS_POINT (s->v2);
-  ns2 = gts_point_distance2 (p1, p2);
-  if (ns2 == 0.0)
-    return gts_point_distance2 (p, p1);
-  t = ((p2->x - p1->x)*(p->x - p1->x) + 
-       (p2->y - p1->y)*(p->y - p1->y) +
-       (p2->z - p1->z)*(p->z - p1->z))/ns2;
-  if (t > 1.0)
-    return gts_point_distance2 (p, p2);
-  if (t < 0.0)
-    return gts_point_distance2 (p, p1);
-  x = (1. - t)*p1->x + t*p2->x - p->x;
-  y = (1. - t)*p1->y + t*p2->y - p->y;
-  z = (1. - t)*p1->z + t*p2->z - p->z;
-  return x*x + y*y + z*z;
-}
-
-/**
- * gts_point_segment_distance:
- * @p: a #GtsPoint.
- * @s: a #GtsSegment.
- *
- * Returns: the minimun Euclidean distance between @p and @s.
- */
-gdouble gts_point_segment_distance (GtsPoint * p, GtsSegment * s)
-{
-  g_return_val_if_fail (p != NULL, 0.0);
-  g_return_val_if_fail (s != NULL, 0.0);
-
-  return sqrt (gts_point_segment_distance2 (p, s));
-}
-
-/**
- * gts_point_segment_closest:
- * @p: a #GtsPoint.
- * @s: a #GtsSegment.
- * @closest: a #GtsPoint.
- *
- * Set the coordinates of @closest to the coordinates of the point belonging
- * to @s closest to @p.
- */
-void gts_point_segment_closest (GtsPoint * p, 
-				GtsSegment * s,
-				GtsPoint * closest)
-{
-  gdouble t, ns2;
-  GtsPoint * p1, * p2;
-
-  g_return_if_fail (p != NULL);
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (closest != NULL);
-
-  p1 = GTS_POINT (s->v1);
-  p2 = GTS_POINT (s->v2);
-  ns2 = gts_point_distance2 (p1, p2);
-
-  if (ns2 == 0.0) {
-    gts_point_set (closest, p1->x, p1->y, p1->z);
-    return;
-  }
-
-  t = ((p2->x - p1->x)*(p->x - p1->x) + 
-       (p2->y - p1->y)*(p->y - p1->y) +
-       (p2->z - p1->z)*(p->z - p1->z))/ns2;
-
-  if (t > 1.0)
-    gts_point_set (closest, p2->x, p2->y, p2->z);
-  else if (t < 0.0)
-    gts_point_set (closest, p1->x, p1->y, p1->z);
-  else
-    gts_point_set (closest,
-		   (1. - t)*p1->x + t*p2->x,
-		   (1. - t)*p1->y + t*p2->y,
-		   (1. - t)*p1->z + t*p2->z);
-}
-
-/**
- * gts_point_triangle_distance2:
- * @p: a #GtsPoint.
- * @t: a #GtsTriangle.
- *
- * Returns: the square of the minimun Euclidean distance between @p and @t.
- */
-gdouble gts_point_triangle_distance2 (GtsPoint * p, GtsTriangle * t)
-{
-  GtsPoint * p1, * p2, * p3;
-  GtsEdge * e1, * e2, * e3;
-  GtsVector p1p2, p1p3, pp1;
-  gdouble A, B, C, D, E, det;
-  gdouble t1, t2;
-  gdouble x, y, z;
-
-  g_return_val_if_fail (p != NULL, 0.0);
-  g_return_val_if_fail (t != NULL, 0.0);
-
-  gts_triangle_vertices_edges (t, NULL, 
-			       (GtsVertex **) &p1, 
-			       (GtsVertex **) &p2, 
-			       (GtsVertex **) &p3, 
-			       &e1, &e2, &e3);
-
-  gts_vector_init (p1p2, p1, p2);
-  gts_vector_init (p1p3, p1, p3);
-  gts_vector_init (pp1, p, p1);
-
-  B = gts_vector_scalar (p1p3, p1p2);
-  E = gts_vector_scalar (p1p2, p1p2);
-  C = gts_vector_scalar (p1p3, p1p3);
-  
-  det = B*B - E*C;
-  if (det == 0.) { /* p1p2 and p1p3 are colinear */
-    gdouble d1 = gts_point_segment_distance2 (p, GTS_SEGMENT (e1));
-    gdouble d2 = gts_point_segment_distance2 (p, GTS_SEGMENT (e3));
-    if (d1 < d2)
-      return d1;
-    return d2;
-  }
-
-  A = gts_vector_scalar (p1p3, pp1);
-  D = gts_vector_scalar (p1p2, pp1);
-  
-  t1 = (D*C - A*B)/det;
-  t2 = (A*E - D*B)/det;
-
-  if (t1 < 0.)
-    return gts_point_segment_distance2 (p, GTS_SEGMENT (e3));
-  if (t2 < 0.)
-    return gts_point_segment_distance2 (p, GTS_SEGMENT (e1));
-  if (t1 + t2 > 1.)
-    return gts_point_segment_distance2 (p, GTS_SEGMENT (e2));
-
-  x = pp1[0] + t1*p1p2[0] + t2*p1p3[0];
-  y = pp1[1] + t1*p1p2[1] + t2*p1p3[1];
-  z = pp1[2] + t1*p1p2[2] + t2*p1p3[2];
-
-  return x*x + y*y + z*z;
-}
-
-/**
- * gts_point_triangle_distance:
- * @p: a #GtsPoint.
- * @t: a #GtsTriangle.
- *
- * Returns: the minimun Euclidean distance between @p and @t.
- */
-gdouble gts_point_triangle_distance (GtsPoint * p, GtsTriangle * t)
-{
-  g_return_val_if_fail (p != NULL, 0.0);
-  g_return_val_if_fail (t != NULL, 0.0);
-
-  return sqrt (gts_point_triangle_distance2 (p, t));
-}
-
-/**
- * gts_point_triangle_closest:
- * @p: a #GtsPoint.
- * @t: a #GtsTriangle.
- * @closest: a #GtsPoint.
- *
- * Set the coordinates of @closest to those of the point belonging to @t and 
- * closest to @p.
- */
-void gts_point_triangle_closest (GtsPoint * p, 
-				 GtsTriangle * t, 
-				 GtsPoint * closest)
-{
-  GtsPoint * p1, * p2, * p3;
-  GtsEdge * e1, * e2, * e3;
-  GtsVector p1p2, p1p3, pp1;
-  gdouble A, B, C, D, E, det;
-  gdouble t1, t2;
-
-  g_return_if_fail (p != NULL);
-  g_return_if_fail (t != NULL);
-  g_return_if_fail (closest != NULL);
-
-  gts_triangle_vertices_edges (t, NULL, 
-			       (GtsVertex **) &p1, 
-			       (GtsVertex **) &p2, 
-			       (GtsVertex **) &p3, 
-			       &e1, &e2, &e3);
-
-  gts_vector_init (p1p2, p1, p2);
-  gts_vector_init (p1p3, p1, p3);
-  gts_vector_init (pp1, p, p1);
-
-  B = gts_vector_scalar (p1p3, p1p2);
-  E = gts_vector_scalar (p1p2, p1p2);
-  C = gts_vector_scalar (p1p3, p1p3);
-  
-  det = B*B - E*C;
-  if (det == 0.) { /* p1p2 and p1p3 are colinear */
-    GtsPoint * cp = 
-      GTS_POINT (gts_object_new (GTS_OBJECT_CLASS (gts_point_class ())));
-    gts_point_segment_closest (p, GTS_SEGMENT (e1), cp);
-    gts_point_segment_closest (p, GTS_SEGMENT (e3), closest);
-
-    if (gts_point_distance2 (cp, p) < gts_point_distance2 (closest, p))
-      gts_point_set (closest, cp->x, cp->y, cp->z);
-    gts_object_destroy (GTS_OBJECT (cp));
-    return;
-  }
-
-  A = gts_vector_scalar (p1p3, pp1);
-  D = gts_vector_scalar (p1p2, pp1);
-  
-  t1 = (D*C - A*B)/det;
-  t2 = (A*E - D*B)/det;
-
-  if (t1 < 0.)
-    gts_point_segment_closest (p, GTS_SEGMENT (e3), closest);
-  else if (t2 < 0.)
-    gts_point_segment_closest (p, GTS_SEGMENT (e1), closest);
-  else if (t1 + t2 > 1.)
-    gts_point_segment_closest (p, GTS_SEGMENT (e2), closest);
-  else
-    gts_point_set (closest, 
-		   p1->x + t1*p1p2[0] + t2*p1p3[0],
-		   p1->y + t1*p1p2[1] + t2*p1p3[1],
-		   p1->z + t1*p1p2[2] + t2*p1p3[2]);
-}
-
-/**
- * gts_segment_triangle_intersection:
- * @s: a #GtsSegment.
- * @t: a #GtsTriangle.
- * @boundary: if %TRUE, the boundary of @t is taken into account.
- * @klass: a #GtsPointClass to be used for the new point.
- *
- * Checks if @s intersects @t. If this is the case, creates a new
- * point pi intersection of @s with @t.
- *
- * This function is geometrically robust in the sense that it will not
- * return a point if @s and @t do not intersect and will return a
- * point if @s and @t do intersect. However, the point coordinates are
- * subject to round-off errors.
- *
- * Note that this function will not return any point if @s is contained in
- * the plane defined by @t.
- * 
- * Returns: a summit of @t (if @boundary is set to %TRUE), one of the endpoints
- * of @s or a new #GtsPoint, intersection of @s with @t or %NULL if @s 
- * and @t don't intersect.  
- */
-GtsPoint * gts_segment_triangle_intersection (GtsSegment * s,
-					      GtsTriangle * t,
-					      gboolean boundary,
-					      GtsPointClass * klass)
-{
-  GtsPoint * A, * B, * C, * D, * E, * I;
-  gdouble ABCE, ABCD, ADCE, ABDE, BCDE;
-  gdouble c;
-
-  g_return_val_if_fail (s != NULL, NULL);
-  g_return_val_if_fail (t != NULL, NULL);
-  g_return_val_if_fail (klass != NULL, NULL);
-
-  A = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
-  B = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
-  C = GTS_POINT (gts_triangle_vertex (t));
-  D = GTS_POINT (s->v1); 
-  E = GTS_POINT (s->v2);
-
-  ABCE = gts_point_orientation_3d (A, B, C, E);
-  ABCD = gts_point_orientation_3d (A, B, C, D);
-  if (ABCE < 0.0 || ABCD > 0.0) {
-    GtsPoint * tmpp;
-    gdouble tmp;
-    tmpp = E; E = D; D = tmpp;
-    tmp = ABCE; ABCE = ABCD; ABCD = tmp;
-  }
-  if (ABCE < 0.0 || ABCD > 0.0)
-    return NULL;
-  ADCE = gts_point_orientation_3d (A, D, C, E);
-  if ((boundary && ADCE < 0.) || (!boundary && ADCE <= 0.))
-    return NULL;
-  ABDE = gts_point_orientation_3d (A, B, D, E);
-  if ((boundary && ABDE < 0.) || (!boundary && ABDE <= 0.))
-    return NULL;
-  BCDE = gts_point_orientation_3d (B, C, D, E);
-  if ((boundary && BCDE < 0.) || (!boundary && BCDE <= 0.))
-    return NULL;
-  if (ABCE == 0.0) {
-    if (ABCD == 0.0)
-      /* s is contained in the plane defined by t*/
-      return NULL;
-    return E;
-  }
-  if (ABCD == 0.0)
-    return D;
-  if (boundary) { /* corners of @t */
-    if (ABDE == 0.) {
-      if (ADCE == 0.)
-	return A;
-      if (BCDE == 0.)
-	return B;
-    }
-    else if (BCDE == 0. && ADCE == 0.)
-      return C;
-  }
-  c = ABCE/(ABCE - ABCD);
-  I = GTS_POINT (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  gts_point_set (I,
-		 E->x + c*(D->x - E->x),
-		 E->y + c*(D->y - E->y),
-		 E->z + c*(D->z - E->z));
-  return I;
-}
-
-/**
- * gts_point_transform:
- * @p: a #GtsPoint.
- * @m: the #GtsMatrix representing the transformation to 
- * apply to the coordinates of @p.
- *
- * Transform the coordinates of @p according to @m. (p[] becomes m[][].p[]).
- */
-void gts_point_transform (GtsPoint * p, GtsMatrix * m)
-{
-  gdouble x, y, z;
-  g_return_if_fail (p != NULL && m != NULL);
-  x = m[0][0]*p->x + m[0][1]*p->y + m[0][2]*p->z + m[0][3];
-  y = m[1][0]*p->x + m[1][1]*p->y + m[1][2]*p->z + m[1][3];
-  z = m[2][0]*p->x + m[2][1]*p->y + m[2][2]*p->z + m[2][3];
-  p->x = x; p->y = y; p->z = z;
-}
-
-/**
- * gts_point_orientation:
- * @p1: a #GtsPoint.
- * @p2: a #GtsPoint.
- * @p3: a #GtsPoint.
- *
- * Checks for orientation of the projection of three points on the
- * (x,y) plane. The result is also an approximation of twice the
- * signed area of the triangle defined by the three points. This
- * function uses adaptive floating point arithmetic and is
- * consequently geometrically robust.
- *
- * Returns: a positive value if @p1, @p2 and @p3 appear in
- * counterclockwise order, a negative value if they appear in
- * clockwise order and zero if they are colinear.  
- */
-gdouble gts_point_orientation (GtsPoint * p1, GtsPoint * p2, GtsPoint * p3)
-{
-  g_return_val_if_fail (p1 != NULL && p2 != NULL && p3 != NULL, 0.0);
-
-  return orient2d ((gdouble *) &p1->x, 
-		   (gdouble *) &p2->x, 
-		   (gdouble *) &p3->x);
-}
-
-static gboolean ray_intersects_triangle (GtsPoint * D, GtsPoint * E,
-					 GtsTriangle * t)
-{
-  GtsPoint * A, * B, * C;
-  gint ABCE, ABCD, ADCE, ABDE, BCDE;
-
-  gts_triangle_vertices (t, (GtsVertex **) &A, 
-			 (GtsVertex **) &B, 
-			 (GtsVertex **) &C);
-
-  ABCE = gts_point_orientation_3d_sos (A, B, C, E);
-  ABCD = gts_point_orientation_3d_sos (A, B, C, D);
-  if (ABCE < 0 || ABCD > 0) {
-    GtsPoint * tmpp;
-    gint tmp;
-
-    tmpp = E; E = D; D = tmpp;
-    tmp = ABCE; ABCE = ABCD; ABCD = tmp;
-  }
-  if (ABCE < 0 || ABCD > 0)
-    return FALSE;
-  ADCE = gts_point_orientation_3d_sos (A, D, C, E);
-  if (ADCE < 0)
-    return FALSE;
-  ABDE = gts_point_orientation_3d_sos (A, B, D, E);
-  if (ABDE < 0)
-    return FALSE;
-  BCDE = gts_point_orientation_3d_sos (B, C, D, E);
-  if (BCDE < 0)
-    return FALSE;
-  return TRUE;
-}
-
-/** 
- * gts_point_is_inside_surface: 
- * @p: a #GtsPoint.  
- * @tree: a bounding box tree of the faces of a closed, orientable
- * surface (see gts_bb_tree_surface()).
- * @is_open: %TRUE if the surface defined by @tree is "open" i.e. its volume 
- * is negative, %FALSE otherwise.
- *
- * Returns: %TRUE if @p is inside the surface defined by @tree, %FALSE
- * otherwise.  
- */
-gboolean gts_point_is_inside_surface (GtsPoint * p, 
-				      GNode * tree,
-				      gboolean is_open)
-{
-  GSList * list, * i;
-  guint nc = 0;
-  GtsPoint * p1;
-  GtsBBox * bb;
-
-  g_return_val_if_fail (p != NULL, FALSE);
-  g_return_val_if_fail (tree != NULL, FALSE);
-
-  bb = tree->data;
-  p1 = gts_point_new (gts_point_class (), bb->x2 + fabs (bb->x2)/10., p->y, p->z);
-  i = list = gts_bb_tree_stabbed (tree, p);
-  while (i) {
-    GtsTriangle * t = GTS_TRIANGLE (GTS_BBOX (i->data)->bounded);
-
-    if (ray_intersects_triangle (p, p1, t))
-      nc++;
-    i = i->next;
-  }
-  g_slist_free (list);
-  gts_object_destroy (GTS_OBJECT (p1));
-
-  return is_open ? (nc % 2 == 0) : (nc % 2 != 0);
-}
-
-#define SIGN(x) ((x) > 0. ? 1 : -1)
-#define ORIENT1D(a,b) ((a) > (b) ? 1 : (a) < (b) ? -1 : 0)
-
-static gint sortp (gpointer * p, guint n)
-{
-  gint sign = 1;
-  guint i, j;
-
-  for (i = 0; i < n - 1; i++)
-    for (j = 0; j < n - 1 - i; j++)
-      if (GPOINTER_TO_UINT (p[j+1]) < GPOINTER_TO_UINT (p[j])) {
-	gpointer tmp = p[j];
-
-	p[j] = p[j+1];
-	p[j+1] = tmp;
-	sign = - sign;
-      }
-  return sign;
-}
-
-/**
- * gts_point_orientation_3d_sos:
- * @p1: a #GtsPoint.
- * @p2: a #GtsPoint.
- * @p3: a #GtsPoint.
- * @p4: a #GtsPoint.
- *
- * Checks if @p4 lies above or below the plane passing through the
- * points @p1, @p2 and @p3. Below is defined so that @p1, @p2 and @p3
- * appear in counterclockwise order when viewed from above the
- * plane. This function uses adaptive floating point arithmetic and is
- * consequently geometrically robust.
- *
- * Simulation of Simplicity (SoS) is used to break ties when the
- * orientation is degenerate (i.e. @p4 lies on the plane defined by
- * @p1, @p2 and @p3).
- *
- * Returns: +1 if @p4 lies below, -1 if @p4 lies above the plane.  
- */
-gint gts_point_orientation_3d_sos (GtsPoint * p1,
-				   GtsPoint * p2,
-				   GtsPoint * p3,
-				   GtsPoint * p4)
-{
-  gdouble o;
-
-  g_return_val_if_fail (p1 != NULL && p2 != NULL && 
-			p3 != NULL && p4 != NULL, 0);
-
-  o = orient3d ((gdouble *) &p1->x, 
-		(gdouble *) &p2->x, 
-		(gdouble *) &p3->x, 
-		(gdouble *) &p4->x);
-  if (o != 0.)
-    return SIGN (o);
-  else {
-    GtsPoint * p[4];
-    gdouble a[2], b[2], c[2];
-    gint sign;
-
-    p[0] = p1; p[1] = p2; p[2] = p3; p[3] = p4;
-    sign = sortp ((gpointer *) p, 4);
-    
-    /* epsilon^1/8 */
-    a[0] = p[1]->x; a[1] = p[1]->y;
-    b[0] = p[2]->x; b[1] = p[2]->y;
-    c[0] = p[3]->x; c[1] = p[3]->y;
-    o = orient2d (a, b, c);
-    if (o != 0.)
-      return SIGN (o)*sign;
-    
-    /* epsilon^1/4 */
-    a[0] = p[1]->x; a[1] = p[1]->z;
-    b[0] = p[2]->x; b[1] = p[2]->z;
-    c[0] = p[3]->x; c[1] = p[3]->z;
-    o = orient2d (a, b, c);
-    if (o != 0.)
-      return - SIGN (o)*sign;
-    
-    /* epsilon^1/2 */
-    a[0] = p[1]->y; a[1] = p[1]->z;
-    b[0] = p[2]->y; b[1] = p[2]->z;
-    c[0] = p[3]->y; c[1] = p[3]->z;
-    o = orient2d (a, b, c);
-    if (o != 0.)
-      return SIGN (o)*sign;
-    
-    /* epsilon */
-    a[0] = p[0]->x; a[1] = p[0]->y;
-    b[0] = p[2]->x; b[1] = p[2]->y;
-    c[0] = p[3]->x; c[1] = p[3]->y;
-    o = orient2d (a, b, c);
-    if (o != 0.)
-      return - SIGN (o)*sign;
-    
-    /* epsilon^5/4 */
-    o = ORIENT1D (p[2]->x, p[3]->x);
-    if (o != 0.)
-      return SIGN (o)*sign;
-    
-    /* epsilon^3/2 */
-    o = ORIENT1D (p[2]->y, p[3]->y);
-    if (o != 0.)
-      return - SIGN (o)*sign;
-    
-    /* epsilon^2 */
-    a[0] = p[0]->x; a[1] = p[0]->z;
-    b[0] = p[2]->x; b[1] = p[2]->z;
-    c[0] = p[3]->x; c[1] = p[3]->z;
-    o = orient2d (a, b, c);
-    if (o != 0.)
-      return SIGN (o)*sign;
-
-    /* epsilon^5/2 */
-    o = ORIENT1D (p[2]->z, p[3]->z);
-    if (o != 0.)
-      return SIGN (o)*sign;
-    
-    /* epsilon^4 */
-    a[0] = p[0]->y; a[1] = p[0]->z;
-    b[0] = p[2]->y; b[1] = p[2]->z;
-    c[0] = p[3]->y; c[1] = p[3]->z;
-    o = orient2d (a, b, c);
-    if (o != 0.)
-      return - SIGN (o)*sign;
-
-    /* epsilon^8 */
-    a[0] = p[0]->x; a[1] = p[0]->y;
-    b[0] = p[1]->x; b[1] = p[1]->y;
-    c[0] = p[3]->x; c[1] = p[3]->y;
-    o = orient2d (a, b, c);
-    if (o != 0.)
-      return SIGN (o)*sign;
-
-    /* epsilon^33/4 */
-    o = ORIENT1D (p[1]->x, p[3]->x);
-    if (o != 0.)
-      return - SIGN (o)*sign;
-    
-    /* epsilon^17/2 */
-    o = ORIENT1D (p[1]->y, p[3]->y);
-    if (o != 0.)
-      return SIGN (o)*sign;
-    
-    /* epsilon^10 */
-    o = ORIENT1D (p[0]->x, p[3]->x);
-    if (o != 0.)
-      return SIGN (o)*sign;
-    
-    /* epsilon^21/2 */
-    return sign;
-  }
-}
-
-/**
- * gts_point_orientation_sos:
- * @p1: a #GtsPoint.
- * @p2: a #GtsPoint.
- * @p3: a #GtsPoint.
- *
- * Checks for orientation of the projection of three points on the
- * (x,y) plane.
- *
- * Simulation of Simplicity (SoS) is used to break ties when the
- * orientation is degenerate (i.e. @p3 lies on the line defined by
- * @p1 and @p2).
- *
- * Returns: a positive value if @p1, @p2 and @p3 appear in
- * counterclockwise order or a negative value if they appear in
- * clockwise order.  
- */
-gint gts_point_orientation_sos (GtsPoint * p1,
-				GtsPoint * p2,
-				GtsPoint * p3)
-{
-  gdouble o;
-
-  g_return_val_if_fail (p1 != NULL && p2 != NULL && p3 != NULL, 0);
-
-  o = orient2d ((gdouble *) &p1->x, 
-		(gdouble *) &p2->x, 
-		(gdouble *) &p3->x);
-  if (o != 0.)
-    return SIGN (o);
-  else {
-    GtsPoint * p[3];
-    gint sign;
-
-    p[0] = p1; p[1] = p2; p[2] = p3;
-    sign = sortp ((gpointer *) p, 3);
-    
-    /* epsilon^1/4 */
-    o = ORIENT1D (p[1]->x, p[2]->x);
-    if (o != 0.)
-      return - SIGN (o)*sign;
-    
-    /* epsilon^1/2 */
-    o = ORIENT1D (p[1]->y, p[2]->y);
-    if (o != 0.)
-      return SIGN (o)*sign;
-    
-    /* epsilon */
-    o = ORIENT1D (p[0]->x, p[2]->x);
-    if (o != 0.)
-      return SIGN (o)*sign;
-    
-    /* epsilon^3/2 */
-    return sign;
-  }
-}
diff --git a/src/gts/predicates.c b/src/gts/predicates.c
deleted file mode 100644
index 7b7fcf2..0000000
--- a/src/gts/predicates.c
+++ /dev/null
@@ -1,2742 +0,0 @@
-/*****************************************************************************/
-/*                                                                           */
-/*  Routines for Arbitrary Precision Floating-point Arithmetic               */
-/*  and Fast Robust Geometric Predicates                                     */
-/*  (predicates.c)                                                           */
-/*                                                                           */
-/*  May 18, 1996                                                             */
-/*                                                                           */
-/*  Placed in the public domain by                                           */
-/*  Jonathan Richard Shewchuk                                                */
-/*  School of Computer Science                                               */
-/*  Carnegie Mellon University                                               */
-/*  5000 Forbes Avenue                                                       */
-/*  Pittsburgh, Pennsylvania  15213-3891                                     */
-/*  jrs@xxxxxxxxxx                                                           */
-/*                                                                           */
-/*  This file contains C implementation of algorithms for exact addition     */
-/*    and multiplication of floating-point numbers, and predicates for       */
-/*    robustly performing the orientation and incircle tests used in         */
-/*    computational geometry.  The algorithms and underlying theory are      */
-/*    described in Jonathan Richard Shewchuk.  "Adaptive Precision Floating- */
-/*    Point Arithmetic and Fast Robust Geometric Predicates."  Technical     */
-/*    Report CMU-CS-96-140, School of Computer Science, Carnegie Mellon      */
-/*    University, Pittsburgh, Pennsylvania, May 1996.  (Submitted to         */
-/*    Discrete & Computational Geometry.)                                    */
-/*                                                                           */
-/*  This file, the paper listed above, and other information are available   */
-/*    from the Web page http://www.cs.cmu.edu/~quake/robust.html .           */
-/*                                                                           */
-/*****************************************************************************/
-
-/*****************************************************************************/
-/*                                                                           */
-/*  Using this code:                                                         */
-/*                                                                           */
-/*  First, read the short or long version of the paper (from the Web page    */
-/*    above).                                                                */
-/*                                                                           */
-/*  Be sure to call exactinit() once, before calling any of the arithmetic   */
-/*    functions or geometric predicates.  Also be sure to turn on the        */
-/*    optimizer when compiling this file.                                    */
-/*                                                                           */
-/*                                                                           */
-/*  Several geometric predicates are defined.  Their parameters are all      */
-/*    points.  Each point is an array of two or three floating-point         */
-/*    numbers.  The geometric predicates, described in the papers, are       */
-/*                                                                           */
-/*    orient2d(pa, pb, pc)                                                   */
-/*    orient2dfast(pa, pb, pc)                                               */
-/*    orient3d(pa, pb, pc, pd)                                               */
-/*    orient3dfast(pa, pb, pc, pd)                                           */
-/*    incircle(pa, pb, pc, pd)                                               */
-/*    incirclefast(pa, pb, pc, pd)                                           */
-/*    insphere(pa, pb, pc, pd, pe)                                           */
-/*    inspherefast(pa, pb, pc, pd, pe)                                       */
-/*                                                                           */
-/*  Those with suffix "fast" are approximate, non-robust versions.  Those    */
-/*    without the suffix are adaptive precision, robust versions.  There     */
-/*    are also versions with the suffices "exact" and "slow", which are      */
-/*    non-adaptive, exact arithmetic versions, which I use only for timings  */
-/*    in my arithmetic papers.                                               */
-/*                                                                           */
-/*                                                                           */
-/*  An expansion is represented by an array of floating-point numbers,       */
-/*    sorted from smallest to largest magnitude (possibly with interspersed  */
-/*    zeros).  The length of each expansion is stored as a separate integer, */
-/*    and each arithmetic function returns an integer which is the length    */
-/*    of the expansion it created.                                           */
-/*                                                                           */
-/*  Several arithmetic functions are defined.  Their parameters are          */
-/*                                                                           */
-/*    e, f           Input expansions                                        */
-/*    elen, flen     Lengths of input expansions (must be >= 1)              */
-/*    h              Output expansion                                        */
-/*    b              Input scalar                                            */
-/*                                                                           */
-/*  The arithmetic functions are                                             */
-/*                                                                           */
-/*    grow_expansion(elen, e, b, h)                                          */
-/*    grow_expansion_zeroelim(elen, e, b, h)                                 */
-/*    expansion_sum(elen, e, flen, f, h)                                     */
-/*    expansion_sum_zeroelim1(elen, e, flen, f, h)                           */
-/*    expansion_sum_zeroelim2(elen, e, flen, f, h)                           */
-/*    fast_expansion_sum(elen, e, flen, f, h)                                */
-/*    fast_expansion_sum_zeroelim(elen, e, flen, f, h)                       */
-/*    linear_expansion_sum(elen, e, flen, f, h)                              */
-/*    linear_expansion_sum_zeroelim(elen, e, flen, f, h)                     */
-/*    scale_expansion(elen, e, b, h)                                         */
-/*    scale_expansion_zeroelim(elen, e, b, h)                                */
-/*    compress(elen, e, h)                                                   */
-/*                                                                           */
-/*  All of these are described in the long version of the paper; some are    */
-/*    described in the short version.  All return an integer that is the     */
-/*    length of h.  Those with suffix _zeroelim perform zero elimination,    */
-/*    and are recommended over their counterparts.  The procedure            */
-/*    fast_expansion_sum_zeroelim() (or linear_expansion_sum_zeroelim() on   */
-/*    processors that do not use the round-to-even tiebreaking rule) is      */
-/*    recommended over expansion_sum_zeroelim().  Each procedure has a       */
-/*    little note next to it (in the code below) that tells you whether or   */
-/*    not the output expansion may be the same array as one of the input     */
-/*    expansions.                                                            */
-/*                                                                           */
-/*                                                                           */
-/*  If you look around below, you'll also find macros for a bunch of         */
-/*    simple unrolled arithmetic operations, and procedures for printing     */
-/*    expansions (commented out because they don't work with all C           */
-/*    compilers) and for generating random floating-point numbers whose      */
-/*    significand bits are all random.  Most of the macros have undocumented */
-/*    requirements that certain of their parameters should not be the same   */
-/*    variable; for safety, better to make sure all the parameters are       */
-/*    distinct variables.  Feel free to send email to jrs@xxxxxxxxxx if you  */
-/*    have questions.                                                        */
-/*                                                                           */
-/*****************************************************************************/
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <math.h>
-#include "predicates.h"
-
-/* Use header file generated automatically by predicates_init. */
-//#define USE_PREDICATES_INIT
-
-#ifdef USE_PREDICATES_INIT
-#include "predicates_init.h"
-#endif /* USE_PREDICATES_INIT */
-
-/* FPU control. We MUST have only double precision (not extended precision) */
-#include "rounding.h"
-
-/* On some machines, the exact arithmetic routines might be defeated by the  */
-/*   use of internal extended precision floating-point registers.  Sometimes */
-/*   this problem can be fixed by defining certain values to be volatile,    */
-/*   thus forcing them to be stored to memory and rounded off.  This isn't   */
-/*   a great solution, though, as it slows the arithmetic down.              */
-/*                                                                           */
-/* To try this out, write "#define INEXACT volatile" below.  Normally,       */
-/*   however, INEXACT should be defined to be nothing.  ("#define INEXACT".) */
-
-#define INEXACT                          /* Nothing */
-/* #define INEXACT volatile */
-
-#define REAL double                      /* float or double */
-#define REALPRINT doubleprint
-#define REALRAND doublerand
-#define NARROWRAND narrowdoublerand
-#define UNIFORMRAND uniformdoublerand
-
-/* Which of the following two methods of finding the absolute values is      */
-/*   fastest is compiler-dependent.  A few compilers can inline and optimize */
-/*   the fabs() call; but most will incur the overhead of a function call,   */
-/*   which is disastrously slow.  A faster way on IEEE machines might be to  */
-/*   mask the appropriate bit, but that's difficult to do in C.              */
-
-#define Absolute(a)  ((a) >= 0.0 ? (a) : -(a))
-/* #define Absolute(a)  fabs(a) */
-
-/* Many of the operations are broken up into two pieces, a main part that    */
-/*   performs an approximate operation, and a "tail" that computes the       */
-/*   roundoff error of that operation.                                       */
-/*                                                                           */
-/* The operations Fast_Two_Sum(), Fast_Two_Diff(), Two_Sum(), Two_Diff(),    */
-/*   Split(), and Two_Product() are all implemented as described in the      */
-/*   reference.  Each of these macros requires certain variables to be       */
-/*   defined in the calling routine.  The variables `bvirt', `c', `abig',    */
-/*   `_i', `_j', `_k', `_l', `_m', and `_n' are declared `INEXACT' because   */
-/*   they store the result of an operation that may incur roundoff error.    */
-/*   The input parameter `x' (or the highest numbered `x_' parameter) must   */
-/*   also be declared `INEXACT'.                                             */
-
-#define Fast_Two_Sum_Tail(a, b, x, y) \
-  bvirt = x - a; \
-  y = b - bvirt
-
-#define Fast_Two_Sum(a, b, x, y) \
-  x = (REAL) (a + b); \
-  Fast_Two_Sum_Tail(a, b, x, y)
-
-#define Fast_Two_Diff_Tail(a, b, x, y) \
-  bvirt = a - x; \
-  y = bvirt - b
-
-#define Fast_Two_Diff(a, b, x, y) \
-  x = (REAL) (a - b); \
-  Fast_Two_Diff_Tail(a, b, x, y)
-
-#define Two_Sum_Tail(a, b, x, y) \
-  bvirt = (REAL) (x - a); \
-  avirt = x - bvirt; \
-  bround = b - bvirt; \
-  around = a - avirt; \
-  y = around + bround
-
-#define Two_Sum(a, b, x, y) \
-  x = (REAL) (a + b); \
-  Two_Sum_Tail(a, b, x, y)
-
-#define Two_Diff_Tail(a, b, x, y) \
-  bvirt = (REAL) (a - x); \
-  avirt = x + bvirt; \
-  bround = bvirt - b; \
-  around = a - avirt; \
-  y = around + bround
-
-#define Two_Diff(a, b, x, y) \
-  x = (REAL) (a - b); \
-  Two_Diff_Tail(a, b, x, y)
-
-#define Split(a, ahi, alo) \
-  c = (REAL) (splitter * a); \
-  abig = (REAL) (c - a); \
-  ahi = c - abig; \
-  alo = a - ahi
-
-#define Two_Product_Tail(a, b, x, y) \
-  Split(a, ahi, alo); \
-  Split(b, bhi, blo); \
-  err1 = x - (ahi * bhi); \
-  err2 = err1 - (alo * bhi); \
-  err3 = err2 - (ahi * blo); \
-  y = (alo * blo) - err3
-
-#define Two_Product(a, b, x, y) \
-  x = (REAL) (a * b); \
-  Two_Product_Tail(a, b, x, y)
-
-/* Two_Product_Presplit() is Two_Product() where one of the inputs has       */
-/*   already been split.  Avoids redundant splitting.                        */
-
-#define Two_Product_Presplit(a, b, bhi, blo, x, y) \
-  x = (REAL) (a * b); \
-  Split(a, ahi, alo); \
-  err1 = x - (ahi * bhi); \
-  err2 = err1 - (alo * bhi); \
-  err3 = err2 - (ahi * blo); \
-  y = (alo * blo) - err3
-
-/* Two_Product_2Presplit() is Two_Product() where both of the inputs have    */
-/*   already been split.  Avoids redundant splitting.                        */
-
-#define Two_Product_2Presplit(a, ahi, alo, b, bhi, blo, x, y) \
-  x = (REAL) (a * b); \
-  err1 = x - (ahi * bhi); \
-  err2 = err1 - (alo * bhi); \
-  err3 = err2 - (ahi * blo); \
-  y = (alo * blo) - err3
-
-/* Square() can be done more quickly than Two_Product().                     */
-
-#define Square_Tail(a, x, y) \
-  Split(a, ahi, alo); \
-  err1 = x - (ahi * ahi); \
-  err3 = err1 - ((ahi + ahi) * alo); \
-  y = (alo * alo) - err3
-
-#define Square(a, x, y) \
-  x = (REAL) (a * a); \
-  Square_Tail(a, x, y)
-
-/* Macros for summing expansions of various fixed lengths.  These are all    */
-/*   unrolled versions of Expansion_Sum().                                   */
-
-#define Two_One_Sum(a1, a0, b, x2, x1, x0) \
-  Two_Sum(a0, b , _i, x0); \
-  Two_Sum(a1, _i, x2, x1)
-
-#define Two_One_Diff(a1, a0, b, x2, x1, x0) \
-  Two_Diff(a0, b , _i, x0); \
-  Two_Sum( a1, _i, x2, x1)
-
-#define Two_Two_Sum(a1, a0, b1, b0, x3, x2, x1, x0) \
-  Two_One_Sum(a1, a0, b0, _j, _0, x0); \
-  Two_One_Sum(_j, _0, b1, x3, x2, x1)
-
-#define Two_Two_Diff(a1, a0, b1, b0, x3, x2, x1, x0) \
-  Two_One_Diff(a1, a0, b0, _j, _0, x0); \
-  Two_One_Diff(_j, _0, b1, x3, x2, x1)
-
-#define Four_One_Sum(a3, a2, a1, a0, b, x4, x3, x2, x1, x0) \
-  Two_One_Sum(a1, a0, b , _j, x1, x0); \
-  Two_One_Sum(a3, a2, _j, x4, x3, x2)
-
-#define Four_Two_Sum(a3, a2, a1, a0, b1, b0, x5, x4, x3, x2, x1, x0) \
-  Four_One_Sum(a3, a2, a1, a0, b0, _k, _2, _1, _0, x0); \
-  Four_One_Sum(_k, _2, _1, _0, b1, x5, x4, x3, x2, x1)
-
-#define Four_Four_Sum(a3, a2, a1, a0, b4, b3, b1, b0, x7, x6, x5, x4, x3, x2, \
-                      x1, x0) \
-  Four_Two_Sum(a3, a2, a1, a0, b1, b0, _l, _2, _1, _0, x1, x0); \
-  Four_Two_Sum(_l, _2, _1, _0, b4, b3, x7, x6, x5, x4, x3, x2)
-
-#define Eight_One_Sum(a7, a6, a5, a4, a3, a2, a1, a0, b, x8, x7, x6, x5, x4, \
-                      x3, x2, x1, x0) \
-  Four_One_Sum(a3, a2, a1, a0, b , _j, x3, x2, x1, x0); \
-  Four_One_Sum(a7, a6, a5, a4, _j, x8, x7, x6, x5, x4)
-
-#define Eight_Two_Sum(a7, a6, a5, a4, a3, a2, a1, a0, b1, b0, x9, x8, x7, \
-                      x6, x5, x4, x3, x2, x1, x0) \
-  Eight_One_Sum(a7, a6, a5, a4, a3, a2, a1, a0, b0, _k, _6, _5, _4, _3, _2, \
-                _1, _0, x0); \
-  Eight_One_Sum(_k, _6, _5, _4, _3, _2, _1, _0, b1, x9, x8, x7, x6, x5, x4, \
-                x3, x2, x1)
-
-#define Eight_Four_Sum(a7, a6, a5, a4, a3, a2, a1, a0, b4, b3, b1, b0, x11, \
-                       x10, x9, x8, x7, x6, x5, x4, x3, x2, x1, x0) \
-  Eight_Two_Sum(a7, a6, a5, a4, a3, a2, a1, a0, b1, b0, _l, _6, _5, _4, _3, \
-                _2, _1, _0, x1, x0); \
-  Eight_Two_Sum(_l, _6, _5, _4, _3, _2, _1, _0, b4, b3, x11, x10, x9, x8, \
-                x7, x6, x5, x4, x3, x2)
-
-/* Macros for multiplying expansions of various fixed lengths.               */
-
-#define Two_One_Product(a1, a0, b, x3, x2, x1, x0) \
-  Split(b, bhi, blo); \
-  Two_Product_Presplit(a0, b, bhi, blo, _i, x0); \
-  Two_Product_Presplit(a1, b, bhi, blo, _j, _0); \
-  Two_Sum(_i, _0, _k, x1); \
-  Fast_Two_Sum(_j, _k, x3, x2)
-
-#define Four_One_Product(a3, a2, a1, a0, b, x7, x6, x5, x4, x3, x2, x1, x0) \
-  Split(b, bhi, blo); \
-  Two_Product_Presplit(a0, b, bhi, blo, _i, x0); \
-  Two_Product_Presplit(a1, b, bhi, blo, _j, _0); \
-  Two_Sum(_i, _0, _k, x1); \
-  Fast_Two_Sum(_j, _k, _i, x2); \
-  Two_Product_Presplit(a2, b, bhi, blo, _j, _0); \
-  Two_Sum(_i, _0, _k, x3); \
-  Fast_Two_Sum(_j, _k, _i, x4); \
-  Two_Product_Presplit(a3, b, bhi, blo, _j, _0); \
-  Two_Sum(_i, _0, _k, x5); \
-  Fast_Two_Sum(_j, _k, x7, x6)
-
-#define Two_Two_Product(a1, a0, b1, b0, x7, x6, x5, x4, x3, x2, x1, x0) \
-  Split(a0, a0hi, a0lo); \
-  Split(b0, bhi, blo); \
-  Two_Product_2Presplit(a0, a0hi, a0lo, b0, bhi, blo, _i, x0); \
-  Split(a1, a1hi, a1lo); \
-  Two_Product_2Presplit(a1, a1hi, a1lo, b0, bhi, blo, _j, _0); \
-  Two_Sum(_i, _0, _k, _1); \
-  Fast_Two_Sum(_j, _k, _l, _2); \
-  Split(b1, bhi, blo); \
-  Two_Product_2Presplit(a0, a0hi, a0lo, b1, bhi, blo, _i, _0); \
-  Two_Sum(_1, _0, _k, x1); \
-  Two_Sum(_2, _k, _j, _1); \
-  Two_Sum(_l, _j, _m, _2); \
-  Two_Product_2Presplit(a1, a1hi, a1lo, b1, bhi, blo, _j, _0); \
-  Two_Sum(_i, _0, _n, _0); \
-  Two_Sum(_1, _0, _i, x2); \
-  Two_Sum(_2, _i, _k, _1); \
-  Two_Sum(_m, _k, _l, _2); \
-  Two_Sum(_j, _n, _k, _0); \
-  Two_Sum(_1, _0, _j, x3); \
-  Two_Sum(_2, _j, _i, _1); \
-  Two_Sum(_l, _i, _m, _2); \
-  Two_Sum(_1, _k, _i, x4); \
-  Two_Sum(_2, _i, _k, x5); \
-  Two_Sum(_m, _k, x7, x6)
-
-/* An expansion of length two can be squared more quickly than finding the   */
-/*   product of two different expansions of length two, and the result is    */
-/*   guaranteed to have no more than six (rather than eight) components.     */
-
-#define Two_Square(a1, a0, x5, x4, x3, x2, x1, x0) \
-  Square(a0, _j, x0); \
-  _0 = a0 + a0; \
-  Two_Product(a1, _0, _k, _1); \
-  Two_One_Sum(_k, _1, _j, _l, _2, x1); \
-  Square(a1, _j, _1); \
-  Two_Two_Sum(_j, _1, _l, _2, x5, x4, x3, x2)
-
-#ifndef USE_PREDICATES_INIT
-
-static REAL splitter;     /* = 2^ceiling(p / 2) + 1.  Used to split floats in half. */
-/* A set of coefficients used to calculate maximum roundoff errors.          */
-static REAL resulterrbound;
-static REAL ccwerrboundA, ccwerrboundB, ccwerrboundC;
-static REAL o3derrboundA, o3derrboundB, o3derrboundC;
-static REAL iccerrboundA, iccerrboundB, iccerrboundC;
-static REAL isperrboundA, isperrboundB, isperrboundC;
-
-void 
-gts_predicates_init()
-{
-  double half = 0.5;
-  double check = 1.0, lastcheck;
-  int every_other = 1;
-  /* epsilon = 2^(-p).  Used to estimate roundoff errors. */
-  double epsilon = 1.0;   
-
-  FPU_ROUND_DOUBLE;
-
-  splitter = 1.;
-
-  /* Repeatedly divide `epsilon' by two until it is too small to add to   */
-  /* one without causing roundoff.  (Also check if the sum is equal to    */
-  /* the previous sum, for machines that round up instead of using exact  */
-  /* rounding.  Not that this library will work on such machines anyway). */
-  do {
-    lastcheck = check;
-    epsilon *= half;
-    if (every_other) {
-      splitter *= 2.0;
-    }
-    every_other = !every_other;
-    check = 1.0 + epsilon;
-  } while ((check != 1.0) && (check != lastcheck));
-  splitter += 1.0;
-  /* Error bounds for orientation and incircle tests. */
-  resulterrbound = (3.0 + 8.0 * epsilon) * epsilon;
-  ccwerrboundA = (3.0 + 16.0 * epsilon) * epsilon;
-  ccwerrboundB = (2.0 + 12.0 * epsilon) * epsilon;
-  ccwerrboundC = (9.0 + 64.0 * epsilon) * epsilon * epsilon;
-  o3derrboundA = (7.0 + 56.0 * epsilon) * epsilon;
-  o3derrboundB = (3.0 + 28.0 * epsilon) * epsilon;
-  o3derrboundC = (26.0 + 288.0 * epsilon) * epsilon * epsilon;
-  iccerrboundA = (10.0 + 96.0 * epsilon) * epsilon;
-  iccerrboundB = (4.0 + 48.0 * epsilon) * epsilon;
-  iccerrboundC = (44.0 + 576.0 * epsilon) * epsilon * epsilon;
-  isperrboundA = (16.0 + 224.0 * epsilon) * epsilon;
-  isperrboundB = (5.0 + 72.0 * epsilon) * epsilon;
-  isperrboundC = (71.0 + 1408.0 * epsilon) * epsilon * epsilon;
-
-
-  FPU_RESTORE;
-}
-
-#endif /* USE_PREDICATES_INIT */
-
-/*****************************************************************************/
-/*                                                                           */
-/*  doubleprint()   Print the bit representation of a double.                */
-/*                                                                           */
-/*  Useful for debugging exact arithmetic routines.                          */
-/*                                                                           */
-/*****************************************************************************/
-
-/*
-void doubleprint(number)
-double number;
-{
-  unsigned long long no;
-  unsigned long long sign, expo;
-  int exponent;
-  int i, bottomi;
-
-  no = *(unsigned long long *) &number;
-  sign = no & 0x8000000000000000ll;
-  expo = (no >> 52) & 0x7ffll;
-  exponent = (int) expo;
-  exponent = exponent - 1023;
-  if (sign) {
-    printf("-");
-  } else {
-    printf(" ");
-  }
-  if (exponent == -1023) {
-    printf(
-      "0.0000000000000000000000000000000000000000000000000000_     (   )");
-  } else {
-    printf("1.");
-    bottomi = -1;
-    for (i = 0; i < 52; i++) {
-      if (no & 0x0008000000000000ll) {
-        printf("1");
-        bottomi = i;
-      } else {
-        printf("0");
-      }
-      no <<= 1;
-    }
-    printf("_%d  (%d)", exponent, exponent - 1 - bottomi);
-  }
-}
-*/
-
-/*****************************************************************************/
-/*                                                                           */
-/*  floatprint()   Print the bit representation of a float.                  */
-/*                                                                           */
-/*  Useful for debugging exact arithmetic routines.                          */
-/*                                                                           */
-/*****************************************************************************/
-
-/*
-void floatprint(number)
-float number;
-{
-  unsigned no;
-  unsigned sign, expo;
-  int exponent;
-  int i, bottomi;
-
-  no = *(unsigned *) &number;
-  sign = no & 0x80000000;
-  expo = (no >> 23) & 0xff;
-  exponent = (int) expo;
-  exponent = exponent - 127;
-  if (sign) {
-    printf("-");
-  } else {
-    printf(" ");
-  }
-  if (exponent == -127) {
-    printf("0.00000000000000000000000_     (   )");
-  } else {
-    printf("1.");
-    bottomi = -1;
-    for (i = 0; i < 23; i++) {
-      if (no & 0x00400000) {
-        printf("1");
-        bottomi = i;
-      } else {
-        printf("0");
-      }
-      no <<= 1;
-    }
-    printf("_%3d  (%3d)", exponent, exponent - 1 - bottomi);
-  }
-}
-*/
-
-/*****************************************************************************/
-/*                                                                           */
-/*  expansion_print()   Print the bit representation of an expansion.        */
-/*                                                                           */
-/*  Useful for debugging exact arithmetic routines.                          */
-/*                                                                           */
-/*****************************************************************************/
-
-/*
-void expansion_print(elen, e)
-int elen;
-REAL *e;
-{
-  int i;
-
-  for (i = elen - 1; i >= 0; i--) {
-    REALPRINT(e[i]);
-    if (i > 0) {
-      printf(" +\n");
-    } else {
-      printf("\n");
-    }
-  }
-}
-*/
-
-/*****************************************************************************/
-/*                                                                           */
-/*  doublerand()   Generate a double with random 53-bit significand and a    */
-/*                 random exponent in [0, 511].                              */
-/*                                                                           */
-/*****************************************************************************/
-
-/*
-static double doublerand()
-{
-  double result;
-  double expo;
-  long a, b, c;
-  long i;
-
-  a = random();
-  b = random();
-  c = random();
-  result = (double) (a - 1073741824) * 8388608.0 + (double) (b >> 8);
-  for (i = 512, expo = 2; i <= 131072; i *= 2, expo = expo * expo) {
-    if (c & i) {
-      result *= expo;
-    }
-  }
-  return result;
-}
-*/
-
-/*****************************************************************************/
-/*                                                                           */
-/*  narrowdoublerand()   Generate a double with random 53-bit significand    */
-/*                       and a random exponent in [0, 7].                    */
-/*                                                                           */
-/*****************************************************************************/
-
-/*
-static double narrowdoublerand()
-{
-  double result;
-  double expo;
-  long a, b, c;
-  long i;
-
-  a = random();
-  b = random();
-  c = random();
-  result = (double) (a - 1073741824) * 8388608.0 + (double) (b >> 8);
-  for (i = 512, expo = 2; i <= 2048; i *= 2, expo = expo * expo) {
-    if (c & i) {
-      result *= expo;
-    }
-  }
-  return result;
-}
-*/
-
-/*****************************************************************************/
-/*                                                                           */
-/*  uniformdoublerand()   Generate a double with random 53-bit significand.  */
-/*                                                                           */
-/*****************************************************************************/
-
-/*
-static double uniformdoublerand()
-{
-  double result;
-  long a, b;
-
-  a = random();
-  b = random();
-  result = (double) (a - 1073741824) * 8388608.0 + (double) (b >> 8);
-  return result;
-}
-*/
-
-/*****************************************************************************/
-/*                                                                           */
-/*  floatrand()   Generate a float with random 24-bit significand and a      */
-/*                random exponent in [0, 63].                                */
-/*                                                                           */
-/*****************************************************************************/
-
-/*
-static float floatrand()
-{
-  float result;
-  float expo;
-  long a, c;
-  long i;
-
-  a = random();
-  c = random();
-  result = (float) ((a - 1073741824) >> 6);
-  for (i = 512, expo = 2; i <= 16384; i *= 2, expo = expo * expo) {
-    if (c & i) {
-      result *= expo;
-    }
-  }
-  return result;
-}
-*/
-
-/*****************************************************************************/
-/*                                                                           */
-/*  narrowfloatrand()   Generate a float with random 24-bit significand and  */
-/*                      a random exponent in [0, 7].                         */
-/*                                                                           */
-/*****************************************************************************/
-
-/*
-static float narrowfloatrand()
-{
-  float result;
-  float expo;
-  long a, c;
-  long i;
-
-  a = random();
-  c = random();
-  result = (float) ((a - 1073741824) >> 6);
-  for (i = 512, expo = 2; i <= 2048; i *= 2, expo = expo * expo) {
-    if (c & i) {
-      result *= expo;
-    }
-  }
-  return result;
-}
-*/
-
-/*****************************************************************************/
-/*                                                                           */
-/*  uniformfloatrand()   Generate a float with random 24-bit significand.    */
-/*                                                                           */
-/*****************************************************************************/
-
-/*
-static float uniformfloatrand()
-{
-  float result;
-  long a;
-
-  a = random();
-  result = (float) ((a - 1073741824) >> 6);
-  return result;
-}
-*/
-
-/*****************************************************************************/
-/*                                                                           */
-/*  fast_expansion_sum_zeroelim()   Sum two expansions, eliminating zero     */
-/*                                  components from the output expansion.    */
-/*                                                                           */
-/*  Sets h = e + f.  See the long version of my paper for details.           */
-/*                                                                           */
-/*  If round-to-even is used (as with IEEE 754), maintains the strongly      */
-/*  nonoverlapping property.  (That is, if e is strongly nonoverlapping, h   */
-/*  will be also.)  Does NOT maintain the nonoverlapping or nonadjacent      */
-/*  properties.                                                              */
-/*                                                                           */
-/*****************************************************************************/
-
-static int fast_expansion_sum_zeroelim(int elen, REAL *e, 
-				       int flen, REAL *f, REAL *h)
-     /* h cannot be e or f. */
-{
-  REAL Q;
-  INEXACT REAL Qnew;
-  INEXACT REAL hh;
-  INEXACT REAL bvirt;
-  REAL avirt, bround, around;
-  int eindex, findex, hindex;
-  REAL enow, fnow;
-
-  enow = e[0];
-  fnow = f[0];
-  eindex = findex = 0;
-  if ((fnow > enow) == (fnow > -enow)) {
-    Q = enow;
-    enow = e[++eindex];
-  } else {
-    Q = fnow;
-    fnow = f[++findex];
-  }
-  hindex = 0;
-  if ((eindex < elen) && (findex < flen)) {
-    if ((fnow > enow) == (fnow > -enow)) {
-      Fast_Two_Sum(enow, Q, Qnew, hh);
-      enow = e[++eindex];
-    } else {
-      Fast_Two_Sum(fnow, Q, Qnew, hh);
-      fnow = f[++findex];
-    }
-    Q = Qnew;
-    if (hh != 0.0) {
-      h[hindex++] = hh;
-    }
-    while ((eindex < elen) && (findex < flen)) {
-      if ((fnow > enow) == (fnow > -enow)) {
-        Two_Sum(Q, enow, Qnew, hh);
-        enow = e[++eindex];
-      } else {
-        Two_Sum(Q, fnow, Qnew, hh);
-        fnow = f[++findex];
-      }
-      Q = Qnew;
-      if (hh != 0.0) {
-        h[hindex++] = hh;
-      }
-    }
-  }
-  while (eindex < elen) {
-    Two_Sum(Q, enow, Qnew, hh);
-    enow = e[++eindex];
-    Q = Qnew;
-    if (hh != 0.0) {
-      h[hindex++] = hh;
-    }
-  }
-  while (findex < flen) {
-    Two_Sum(Q, fnow, Qnew, hh);
-    fnow = f[++findex];
-    Q = Qnew;
-    if (hh != 0.0) {
-      h[hindex++] = hh;
-    }
-  }
-  if ((Q != 0.0) || (hindex == 0)) {
-    h[hindex++] = Q;
-  }
-  return hindex;
-}
-
-/*****************************************************************************/
-/*                                                                           */
-/*  scale_expansion_zeroelim()   Multiply an expansion by a scalar,          */
-/*                               eliminating zero components from the        */
-/*                               output expansion.                           */
-/*                                                                           */
-/*  Sets h = be.  See either version of my paper for details.                */
-/*                                                                           */
-/*  Maintains the nonoverlapping property.  If round-to-even is used (as     */
-/*  with IEEE 754), maintains the strongly nonoverlapping and nonadjacent    */
-/*  properties as well.  (That is, if e has one of these properties, so      */
-/*  will h.)                                                                 */
-/*                                                                           */
-/*****************************************************************************/
-
-static int scale_expansion_zeroelim(int elen, REAL *e, REAL b, REAL *h)
-     /* e and h cannot be the same. */
-{
-  INEXACT REAL Q, sum;
-  REAL hh;
-  INEXACT REAL product1;
-  REAL product0;
-  int eindex, hindex;
-  REAL enow;
-  INEXACT REAL bvirt;
-  REAL avirt, bround, around;
-  INEXACT REAL c;
-  INEXACT REAL abig;
-  REAL ahi, alo, bhi, blo;
-  REAL err1, err2, err3;
-
-  Split(b, bhi, blo);
-  Two_Product_Presplit(e[0], b, bhi, blo, Q, hh);
-  hindex = 0;
-  if (hh != 0) {
-    h[hindex++] = hh;
-  }
-  for (eindex = 1; eindex < elen; eindex++) {
-    enow = e[eindex];
-    Two_Product_Presplit(enow, b, bhi, blo, product1, product0);
-    Two_Sum(Q, product0, sum, hh);
-    if (hh != 0) {
-      h[hindex++] = hh;
-    }
-    Fast_Two_Sum(product1, sum, Q, hh);
-    if (hh != 0) {
-      h[hindex++] = hh;
-    }
-  }
-  if ((Q != 0.0) || (hindex == 0)) {
-    h[hindex++] = Q;
-  }
-  return hindex;
-}
-
-/*****************************************************************************/
-/*                                                                           */
-/*  estimate()   Produce a one-word estimate of an expansion's value.        */
-/*                                                                           */
-/*  See either version of my paper for details.                              */
-/*                                                                           */
-/*****************************************************************************/
-
-static REAL estimate(int elen, REAL *e)
-{
-  REAL Q;
-  int eindex;
-
-  Q = e[0];
-  for (eindex = 1; eindex < elen; eindex++) {
-    Q += e[eindex];
-  }
-  return Q;
-}
-
-/*****************************************************************************/
-/*                                                                           */
-/*  orient2dfast()   Approximate 2D orientation test.  Nonrobust.            */
-/*  orient2dexact()   Exact 2D orientation test.  Robust.                    */
-/*  orient2dslow()   Another exact 2D orientation test.  Robust.             */
-/*  orient2d()   Adaptive exact 2D orientation test.  Robust.                */
-/*                                                                           */
-/*               Return a positive value if the points pa, pb, and pc occur  */
-/*               in counterclockwise order; a negative value if they occur   */
-/*               in clockwise order; and zero if they are collinear.  The    */
-/*               result is also a rough approximation of twice the signed    */
-/*               area of the triangle defined by the three points.           */
-/*                                                                           */
-/*  Only the first and last routine should be used; the middle two are for   */
-/*  timings.                                                                 */
-/*                                                                           */
-/*  The last three use exact arithmetic to ensure a correct answer.  The     */
-/*  result returned is the determinant of a matrix.  In orient2d() only,     */
-/*  this determinant is computed adaptively, in the sense that exact         */
-/*  arithmetic is used only to the degree it is needed to ensure that the    */
-/*  returned value has the correct sign.  Hence, orient2d() is usually quite */
-/*  fast, but will run more slowly when the input points are collinear or    */
-/*  nearly so.                                                               */
-/*                                                                           */
-/*****************************************************************************/
-
-static REAL orient2dadapt(REAL *pa, REAL *pb, REAL *pc, REAL detsum)
-{
-  INEXACT REAL acx, acy, bcx, bcy;
-  REAL acxtail, acytail, bcxtail, bcytail;
-  INEXACT REAL detleft, detright;
-  REAL detlefttail, detrighttail;
-  REAL det, errbound;
-  REAL B[4], C1[8], C2[12], D[16];
-  INEXACT REAL B3;
-  int C1length, C2length, Dlength;
-  REAL u[4];
-  INEXACT REAL u3;
-  INEXACT REAL s1, t1;
-  REAL s0, t0;
-
-  INEXACT REAL bvirt;
-  REAL avirt, bround, around;
-  INEXACT REAL c;
-  INEXACT REAL abig;
-  REAL ahi, alo, bhi, blo;
-  REAL err1, err2, err3;
-  INEXACT REAL _i, _j;
-  REAL _0;
-
-  acx = (REAL) (pa[0] - pc[0]);
-  bcx = (REAL) (pb[0] - pc[0]);
-  acy = (REAL) (pa[1] - pc[1]);
-  bcy = (REAL) (pb[1] - pc[1]);
-
-  Two_Product(acx, bcy, detleft, detlefttail);
-  Two_Product(acy, bcx, detright, detrighttail);
-
-  Two_Two_Diff(detleft, detlefttail, detright, detrighttail,
-               B3, B[2], B[1], B[0]);
-  B[3] = B3;
-
-  det = estimate(4, B);
-  errbound = ccwerrboundB * detsum;
-  if ((det >= errbound) || (-det >= errbound)) {
-    return det;
-  }
-
-  Two_Diff_Tail(pa[0], pc[0], acx, acxtail);
-  Two_Diff_Tail(pb[0], pc[0], bcx, bcxtail);
-  Two_Diff_Tail(pa[1], pc[1], acy, acytail);
-  Two_Diff_Tail(pb[1], pc[1], bcy, bcytail);
-
-  if ((acxtail == 0.0) && (acytail == 0.0)
-      && (bcxtail == 0.0) && (bcytail == 0.0)) {
-    return det;
-  }
-
-  errbound = ccwerrboundC * detsum + resulterrbound * Absolute(det);
-  det += (acx * bcytail + bcy * acxtail)
-       - (acy * bcxtail + bcx * acytail);
-  if ((det >= errbound) || (-det >= errbound)) {
-    return det;
-  }
-
-  Two_Product(acxtail, bcy, s1, s0);
-  Two_Product(acytail, bcx, t1, t0);
-  Two_Two_Diff(s1, s0, t1, t0, u3, u[2], u[1], u[0]);
-  u[3] = u3;
-  C1length = fast_expansion_sum_zeroelim(4, B, 4, u, C1);
-
-  Two_Product(acx, bcytail, s1, s0);
-  Two_Product(acy, bcxtail, t1, t0);
-  Two_Two_Diff(s1, s0, t1, t0, u3, u[2], u[1], u[0]);
-  u[3] = u3;
-  C2length = fast_expansion_sum_zeroelim(C1length, C1, 4, u, C2);
-
-  Two_Product(acxtail, bcytail, s1, s0);
-  Two_Product(acytail, bcxtail, t1, t0);
-  Two_Two_Diff(s1, s0, t1, t0, u3, u[2], u[1], u[0]);
-  u[3] = u3;
-  Dlength = fast_expansion_sum_zeroelim(C2length, C2, 4, u, D);
-
-  return(D[Dlength - 1]);
-}
-
-REAL orient2d(pa, pb, pc)
-REAL *pa;
-REAL *pb;
-REAL *pc;
-{
-  REAL detleft, detright, det;
-  REAL detsum, errbound;
-  REAL orient;
-
-  FPU_ROUND_DOUBLE;
-
-  detleft = (pa[0] - pc[0]) * (pb[1] - pc[1]);
-  detright = (pa[1] - pc[1]) * (pb[0] - pc[0]);
-  det = detleft - detright;
-
-  if (detleft > 0.0) {
-    if (detright <= 0.0) {
-      FPU_RESTORE;
-      return det;
-    } else {
-      detsum = detleft + detright;
-    }
-  } else if (detleft < 0.0) {
-    if (detright >= 0.0) {
-      FPU_RESTORE;
-      return det;
-    } else {
-      detsum = -detleft - detright;
-    }
-  } else {
-    FPU_RESTORE;
-    return det;
-  }
-
-  errbound = ccwerrboundA * detsum;
-  if ((det >= errbound) || (-det >= errbound)) {
-    FPU_RESTORE;
-    return det;
-  }
-
-  orient = orient2dadapt(pa, pb, pc, detsum);
-  FPU_RESTORE;
-  return orient;
-}
-
-/*****************************************************************************/
-/*                                                                           */
-/*  orient3dfast()   Approximate 3D orientation test.  Nonrobust.            */
-/*  orient3dexact()   Exact 3D orientation test.  Robust.                    */
-/*  orient3dslow()   Another exact 3D orientation test.  Robust.             */
-/*  orient3d()   Adaptive exact 3D orientation test.  Robust.                */
-/*                                                                           */
-/*               Return a positive value if the point pd lies below the      */
-/*               plane passing through pa, pb, and pc; "below" is defined so */
-/*               that pa, pb, and pc appear in counterclockwise order when   */
-/*               viewed from above the plane.  Returns a negative value if   */
-/*               pd lies above the plane.  Returns zero if the points are    */
-/*               coplanar.  The result is also a rough approximation of six  */
-/*               times the signed volume of the tetrahedron defined by the   */
-/*               four points.                                                */
-/*                                                                           */
-/*  Only the first and last routine should be used; the middle two are for   */
-/*  timings.                                                                 */
-/*                                                                           */
-/*  The last three use exact arithmetic to ensure a correct answer.  The     */
-/*  result returned is the determinant of a matrix.  In orient3d() only,     */
-/*  this determinant is computed adaptively, in the sense that exact         */
-/*  arithmetic is used only to the degree it is needed to ensure that the    */
-/*  returned value has the correct sign.  Hence, orient3d() is usually quite */
-/*  fast, but will run more slowly when the input points are coplanar or     */
-/*  nearly so.                                                               */
-/*                                                                           */
-/*****************************************************************************/
-
-static REAL orient3dadapt(REAL *pa, REAL *pb, REAL *pc, REAL *pd, 
-			  REAL permanent)
-{
-  INEXACT REAL adx, bdx, cdx, ady, bdy, cdy, adz, bdz, cdz;
-  REAL det, errbound;
-
-  INEXACT REAL bdxcdy1, cdxbdy1, cdxady1, adxcdy1, adxbdy1, bdxady1;
-  REAL bdxcdy0, cdxbdy0, cdxady0, adxcdy0, adxbdy0, bdxady0;
-  REAL bc[4], ca[4], ab[4];
-  INEXACT REAL bc3, ca3, ab3;
-  REAL adet[8], bdet[8], cdet[8];
-  int alen, blen, clen;
-  REAL abdet[16];
-  int ablen;
-  REAL *finnow, *finother, *finswap;
-  REAL fin1[192], fin2[192];
-  int finlength;
-
-  REAL adxtail, bdxtail, cdxtail;
-  REAL adytail, bdytail, cdytail;
-  REAL adztail, bdztail, cdztail;
-  INEXACT REAL at_blarge, at_clarge;
-  INEXACT REAL bt_clarge, bt_alarge;
-  INEXACT REAL ct_alarge, ct_blarge;
-  REAL at_b[4], at_c[4], bt_c[4], bt_a[4], ct_a[4], ct_b[4];
-  int at_blen, at_clen, bt_clen, bt_alen, ct_alen, ct_blen;
-  INEXACT REAL bdxt_cdy1, cdxt_bdy1, cdxt_ady1;
-  INEXACT REAL adxt_cdy1, adxt_bdy1, bdxt_ady1;
-  REAL bdxt_cdy0, cdxt_bdy0, cdxt_ady0;
-  REAL adxt_cdy0, adxt_bdy0, bdxt_ady0;
-  INEXACT REAL bdyt_cdx1, cdyt_bdx1, cdyt_adx1;
-  INEXACT REAL adyt_cdx1, adyt_bdx1, bdyt_adx1;
-  REAL bdyt_cdx0, cdyt_bdx0, cdyt_adx0;
-  REAL adyt_cdx0, adyt_bdx0, bdyt_adx0;
-  REAL bct[8], cat[8], abt[8];
-  int bctlen, catlen, abtlen;
-  INEXACT REAL bdxt_cdyt1, cdxt_bdyt1, cdxt_adyt1;
-  INEXACT REAL adxt_cdyt1, adxt_bdyt1, bdxt_adyt1;
-  REAL bdxt_cdyt0, cdxt_bdyt0, cdxt_adyt0;
-  REAL adxt_cdyt0, adxt_bdyt0, bdxt_adyt0;
-  REAL u[4], v[12], w[16];
-  INEXACT REAL u3;
-  int vlength, wlength;
-  REAL negate;
-
-  INEXACT REAL bvirt;
-  REAL avirt, bround, around;
-  INEXACT REAL c;
-  INEXACT REAL abig;
-  REAL ahi, alo, bhi, blo;
-  REAL err1, err2, err3;
-  INEXACT REAL _i, _j, _k;
-  REAL _0;
-
-  adx = (REAL) (pa[0] - pd[0]);
-  bdx = (REAL) (pb[0] - pd[0]);
-  cdx = (REAL) (pc[0] - pd[0]);
-  ady = (REAL) (pa[1] - pd[1]);
-  bdy = (REAL) (pb[1] - pd[1]);
-  cdy = (REAL) (pc[1] - pd[1]);
-  adz = (REAL) (pa[2] - pd[2]);
-  bdz = (REAL) (pb[2] - pd[2]);
-  cdz = (REAL) (pc[2] - pd[2]);
-
-  Two_Product(bdx, cdy, bdxcdy1, bdxcdy0);
-  Two_Product(cdx, bdy, cdxbdy1, cdxbdy0);
-  Two_Two_Diff(bdxcdy1, bdxcdy0, cdxbdy1, cdxbdy0, bc3, bc[2], bc[1], bc[0]);
-  bc[3] = bc3;
-  alen = scale_expansion_zeroelim(4, bc, adz, adet);
-
-  Two_Product(cdx, ady, cdxady1, cdxady0);
-  Two_Product(adx, cdy, adxcdy1, adxcdy0);
-  Two_Two_Diff(cdxady1, cdxady0, adxcdy1, adxcdy0, ca3, ca[2], ca[1], ca[0]);
-  ca[3] = ca3;
-  blen = scale_expansion_zeroelim(4, ca, bdz, bdet);
-
-  Two_Product(adx, bdy, adxbdy1, adxbdy0);
-  Two_Product(bdx, ady, bdxady1, bdxady0);
-  Two_Two_Diff(adxbdy1, adxbdy0, bdxady1, bdxady0, ab3, ab[2], ab[1], ab[0]);
-  ab[3] = ab3;
-  clen = scale_expansion_zeroelim(4, ab, cdz, cdet);
-
-  ablen = fast_expansion_sum_zeroelim(alen, adet, blen, bdet, abdet);
-  finlength = fast_expansion_sum_zeroelim(ablen, abdet, clen, cdet, fin1);
-
-  det = estimate(finlength, fin1);
-  errbound = o3derrboundB * permanent;
-  if ((det >= errbound) || (-det >= errbound)) {
-    return det;
-  }
-
-  Two_Diff_Tail(pa[0], pd[0], adx, adxtail);
-  Two_Diff_Tail(pb[0], pd[0], bdx, bdxtail);
-  Two_Diff_Tail(pc[0], pd[0], cdx, cdxtail);
-  Two_Diff_Tail(pa[1], pd[1], ady, adytail);
-  Two_Diff_Tail(pb[1], pd[1], bdy, bdytail);
-  Two_Diff_Tail(pc[1], pd[1], cdy, cdytail);
-  Two_Diff_Tail(pa[2], pd[2], adz, adztail);
-  Two_Diff_Tail(pb[2], pd[2], bdz, bdztail);
-  Two_Diff_Tail(pc[2], pd[2], cdz, cdztail);
-
-  if ((adxtail == 0.0) && (bdxtail == 0.0) && (cdxtail == 0.0)
-      && (adytail == 0.0) && (bdytail == 0.0) && (cdytail == 0.0)
-      && (adztail == 0.0) && (bdztail == 0.0) && (cdztail == 0.0)) {
-    return det;
-  }
-
-  errbound = o3derrboundC * permanent + resulterrbound * Absolute(det);
-  det += (adz * ((bdx * cdytail + cdy * bdxtail)
-                 - (bdy * cdxtail + cdx * bdytail))
-          + adztail * (bdx * cdy - bdy * cdx))
-       + (bdz * ((cdx * adytail + ady * cdxtail)
-                 - (cdy * adxtail + adx * cdytail))
-          + bdztail * (cdx * ady - cdy * adx))
-       + (cdz * ((adx * bdytail + bdy * adxtail)
-                 - (ady * bdxtail + bdx * adytail))
-          + cdztail * (adx * bdy - ady * bdx));
-  if ((det >= errbound) || (-det >= errbound)) {
-    return det;
-  }
-
-  finnow = fin1;
-  finother = fin2;
-
-  if (adxtail == 0.0) {
-    if (adytail == 0.0) {
-      at_b[0] = 0.0;
-      at_blen = 1;
-      at_c[0] = 0.0;
-      at_clen = 1;
-    } else {
-      negate = -adytail;
-      Two_Product(negate, bdx, at_blarge, at_b[0]);
-      at_b[1] = at_blarge;
-      at_blen = 2;
-      Two_Product(adytail, cdx, at_clarge, at_c[0]);
-      at_c[1] = at_clarge;
-      at_clen = 2;
-    }
-  } else {
-    if (adytail == 0.0) {
-      Two_Product(adxtail, bdy, at_blarge, at_b[0]);
-      at_b[1] = at_blarge;
-      at_blen = 2;
-      negate = -adxtail;
-      Two_Product(negate, cdy, at_clarge, at_c[0]);
-      at_c[1] = at_clarge;
-      at_clen = 2;
-    } else {
-      Two_Product(adxtail, bdy, adxt_bdy1, adxt_bdy0);
-      Two_Product(adytail, bdx, adyt_bdx1, adyt_bdx0);
-      Two_Two_Diff(adxt_bdy1, adxt_bdy0, adyt_bdx1, adyt_bdx0,
-                   at_blarge, at_b[2], at_b[1], at_b[0]);
-      at_b[3] = at_blarge;
-      at_blen = 4;
-      Two_Product(adytail, cdx, adyt_cdx1, adyt_cdx0);
-      Two_Product(adxtail, cdy, adxt_cdy1, adxt_cdy0);
-      Two_Two_Diff(adyt_cdx1, adyt_cdx0, adxt_cdy1, adxt_cdy0,
-                   at_clarge, at_c[2], at_c[1], at_c[0]);
-      at_c[3] = at_clarge;
-      at_clen = 4;
-    }
-  }
-  if (bdxtail == 0.0) {
-    if (bdytail == 0.0) {
-      bt_c[0] = 0.0;
-      bt_clen = 1;
-      bt_a[0] = 0.0;
-      bt_alen = 1;
-    } else {
-      negate = -bdytail;
-      Two_Product(negate, cdx, bt_clarge, bt_c[0]);
-      bt_c[1] = bt_clarge;
-      bt_clen = 2;
-      Two_Product(bdytail, adx, bt_alarge, bt_a[0]);
-      bt_a[1] = bt_alarge;
-      bt_alen = 2;
-    }
-  } else {
-    if (bdytail == 0.0) {
-      Two_Product(bdxtail, cdy, bt_clarge, bt_c[0]);
-      bt_c[1] = bt_clarge;
-      bt_clen = 2;
-      negate = -bdxtail;
-      Two_Product(negate, ady, bt_alarge, bt_a[0]);
-      bt_a[1] = bt_alarge;
-      bt_alen = 2;
-    } else {
-      Two_Product(bdxtail, cdy, bdxt_cdy1, bdxt_cdy0);
-      Two_Product(bdytail, cdx, bdyt_cdx1, bdyt_cdx0);
-      Two_Two_Diff(bdxt_cdy1, bdxt_cdy0, bdyt_cdx1, bdyt_cdx0,
-                   bt_clarge, bt_c[2], bt_c[1], bt_c[0]);
-      bt_c[3] = bt_clarge;
-      bt_clen = 4;
-      Two_Product(bdytail, adx, bdyt_adx1, bdyt_adx0);
-      Two_Product(bdxtail, ady, bdxt_ady1, bdxt_ady0);
-      Two_Two_Diff(bdyt_adx1, bdyt_adx0, bdxt_ady1, bdxt_ady0,
-                  bt_alarge, bt_a[2], bt_a[1], bt_a[0]);
-      bt_a[3] = bt_alarge;
-      bt_alen = 4;
-    }
-  }
-  if (cdxtail == 0.0) {
-    if (cdytail == 0.0) {
-      ct_a[0] = 0.0;
-      ct_alen = 1;
-      ct_b[0] = 0.0;
-      ct_blen = 1;
-    } else {
-      negate = -cdytail;
-      Two_Product(negate, adx, ct_alarge, ct_a[0]);
-      ct_a[1] = ct_alarge;
-      ct_alen = 2;
-      Two_Product(cdytail, bdx, ct_blarge, ct_b[0]);
-      ct_b[1] = ct_blarge;
-      ct_blen = 2;
-    }
-  } else {
-    if (cdytail == 0.0) {
-      Two_Product(cdxtail, ady, ct_alarge, ct_a[0]);
-      ct_a[1] = ct_alarge;
-      ct_alen = 2;
-      negate = -cdxtail;
-      Two_Product(negate, bdy, ct_blarge, ct_b[0]);
-      ct_b[1] = ct_blarge;
-      ct_blen = 2;
-    } else {
-      Two_Product(cdxtail, ady, cdxt_ady1, cdxt_ady0);
-      Two_Product(cdytail, adx, cdyt_adx1, cdyt_adx0);
-      Two_Two_Diff(cdxt_ady1, cdxt_ady0, cdyt_adx1, cdyt_adx0,
-                   ct_alarge, ct_a[2], ct_a[1], ct_a[0]);
-      ct_a[3] = ct_alarge;
-      ct_alen = 4;
-      Two_Product(cdytail, bdx, cdyt_bdx1, cdyt_bdx0);
-      Two_Product(cdxtail, bdy, cdxt_bdy1, cdxt_bdy0);
-      Two_Two_Diff(cdyt_bdx1, cdyt_bdx0, cdxt_bdy1, cdxt_bdy0,
-                   ct_blarge, ct_b[2], ct_b[1], ct_b[0]);
-      ct_b[3] = ct_blarge;
-      ct_blen = 4;
-    }
-  }
-
-  bctlen = fast_expansion_sum_zeroelim(bt_clen, bt_c, ct_blen, ct_b, bct);
-  wlength = scale_expansion_zeroelim(bctlen, bct, adz, w);
-  finlength = fast_expansion_sum_zeroelim(finlength, finnow, wlength, w,
-                                          finother);
-  finswap = finnow; finnow = finother; finother = finswap;
-
-  catlen = fast_expansion_sum_zeroelim(ct_alen, ct_a, at_clen, at_c, cat);
-  wlength = scale_expansion_zeroelim(catlen, cat, bdz, w);
-  finlength = fast_expansion_sum_zeroelim(finlength, finnow, wlength, w,
-                                          finother);
-  finswap = finnow; finnow = finother; finother = finswap;
-
-  abtlen = fast_expansion_sum_zeroelim(at_blen, at_b, bt_alen, bt_a, abt);
-  wlength = scale_expansion_zeroelim(abtlen, abt, cdz, w);
-  finlength = fast_expansion_sum_zeroelim(finlength, finnow, wlength, w,
-                                          finother);
-  finswap = finnow; finnow = finother; finother = finswap;
-
-  if (adztail != 0.0) {
-    vlength = scale_expansion_zeroelim(4, bc, adztail, v);
-    finlength = fast_expansion_sum_zeroelim(finlength, finnow, vlength, v,
-                                            finother);
-    finswap = finnow; finnow = finother; finother = finswap;
-  }
-  if (bdztail != 0.0) {
-    vlength = scale_expansion_zeroelim(4, ca, bdztail, v);
-    finlength = fast_expansion_sum_zeroelim(finlength, finnow, vlength, v,
-                                            finother);
-    finswap = finnow; finnow = finother; finother = finswap;
-  }
-  if (cdztail != 0.0) {
-    vlength = scale_expansion_zeroelim(4, ab, cdztail, v);
-    finlength = fast_expansion_sum_zeroelim(finlength, finnow, vlength, v,
-                                            finother);
-    finswap = finnow; finnow = finother; finother = finswap;
-  }
-
-  if (adxtail != 0.0) {
-    if (bdytail != 0.0) {
-      Two_Product(adxtail, bdytail, adxt_bdyt1, adxt_bdyt0);
-      Two_One_Product(adxt_bdyt1, adxt_bdyt0, cdz, u3, u[2], u[1], u[0]);
-      u[3] = u3;
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
-                                              finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-      if (cdztail != 0.0) {
-        Two_One_Product(adxt_bdyt1, adxt_bdyt0, cdztail, u3, u[2], u[1], u[0]);
-        u[3] = u3;
-        finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
-                                                finother);
-        finswap = finnow; finnow = finother; finother = finswap;
-      }
-    }
-    if (cdytail != 0.0) {
-      negate = -adxtail;
-      Two_Product(negate, cdytail, adxt_cdyt1, adxt_cdyt0);
-      Two_One_Product(adxt_cdyt1, adxt_cdyt0, bdz, u3, u[2], u[1], u[0]);
-      u[3] = u3;
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
-                                              finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-      if (bdztail != 0.0) {
-        Two_One_Product(adxt_cdyt1, adxt_cdyt0, bdztail, u3, u[2], u[1], u[0]);
-        u[3] = u3;
-        finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
-                                                finother);
-        finswap = finnow; finnow = finother; finother = finswap;
-      }
-    }
-  }
-  if (bdxtail != 0.0) {
-    if (cdytail != 0.0) {
-      Two_Product(bdxtail, cdytail, bdxt_cdyt1, bdxt_cdyt0);
-      Two_One_Product(bdxt_cdyt1, bdxt_cdyt0, adz, u3, u[2], u[1], u[0]);
-      u[3] = u3;
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
-                                              finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-      if (adztail != 0.0) {
-        Two_One_Product(bdxt_cdyt1, bdxt_cdyt0, adztail, u3, u[2], u[1], u[0]);
-        u[3] = u3;
-        finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
-                                                finother);
-        finswap = finnow; finnow = finother; finother = finswap;
-      }
-    }
-    if (adytail != 0.0) {
-      negate = -bdxtail;
-      Two_Product(negate, adytail, bdxt_adyt1, bdxt_adyt0);
-      Two_One_Product(bdxt_adyt1, bdxt_adyt0, cdz, u3, u[2], u[1], u[0]);
-      u[3] = u3;
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
-                                              finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-      if (cdztail != 0.0) {
-        Two_One_Product(bdxt_adyt1, bdxt_adyt0, cdztail, u3, u[2], u[1], u[0]);
-        u[3] = u3;
-        finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
-                                                finother);
-        finswap = finnow; finnow = finother; finother = finswap;
-      }
-    }
-  }
-  if (cdxtail != 0.0) {
-    if (adytail != 0.0) {
-      Two_Product(cdxtail, adytail, cdxt_adyt1, cdxt_adyt0);
-      Two_One_Product(cdxt_adyt1, cdxt_adyt0, bdz, u3, u[2], u[1], u[0]);
-      u[3] = u3;
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
-                                              finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-      if (bdztail != 0.0) {
-        Two_One_Product(cdxt_adyt1, cdxt_adyt0, bdztail, u3, u[2], u[1], u[0]);
-        u[3] = u3;
-        finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
-                                                finother);
-        finswap = finnow; finnow = finother; finother = finswap;
-      }
-    }
-    if (bdytail != 0.0) {
-      negate = -cdxtail;
-      Two_Product(negate, bdytail, cdxt_bdyt1, cdxt_bdyt0);
-      Two_One_Product(cdxt_bdyt1, cdxt_bdyt0, adz, u3, u[2], u[1], u[0]);
-      u[3] = u3;
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
-                                              finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-      if (adztail != 0.0) {
-        Two_One_Product(cdxt_bdyt1, cdxt_bdyt0, adztail, u3, u[2], u[1], u[0]);
-        u[3] = u3;
-        finlength = fast_expansion_sum_zeroelim(finlength, finnow, 4, u,
-                                                finother);
-        finswap = finnow; finnow = finother; finother = finswap;
-      }
-    }
-  }
-
-  if (adztail != 0.0) {
-    wlength = scale_expansion_zeroelim(bctlen, bct, adztail, w);
-    finlength = fast_expansion_sum_zeroelim(finlength, finnow, wlength, w,
-                                            finother);
-    finswap = finnow; finnow = finother; finother = finswap;
-  }
-  if (bdztail != 0.0) {
-    wlength = scale_expansion_zeroelim(catlen, cat, bdztail, w);
-    finlength = fast_expansion_sum_zeroelim(finlength, finnow, wlength, w,
-                                            finother);
-    finswap = finnow; finnow = finother; finother = finswap;
-  }
-  if (cdztail != 0.0) {
-    wlength = scale_expansion_zeroelim(abtlen, abt, cdztail, w);
-    finlength = fast_expansion_sum_zeroelim(finlength, finnow, wlength, w,
-                                            finother);
-    finswap = finnow; finnow = finother; finother = finswap;
-  }
-
-  return finnow[finlength - 1];
-}
-
-REAL orient3d(pa, pb, pc, pd)
-REAL *pa;
-REAL *pb;
-REAL *pc;
-REAL *pd;
-{
-  REAL adx, bdx, cdx, ady, bdy, cdy, adz, bdz, cdz;
-  REAL bdxcdy, cdxbdy, cdxady, adxcdy, adxbdy, bdxady;
-  REAL det;
-  REAL permanent, errbound;
-  REAL orient;
-
-  FPU_ROUND_DOUBLE;
-
-  adx = pa[0] - pd[0];
-  bdx = pb[0] - pd[0];
-  cdx = pc[0] - pd[0];
-  ady = pa[1] - pd[1];
-  bdy = pb[1] - pd[1];
-  cdy = pc[1] - pd[1];
-  adz = pa[2] - pd[2];
-  bdz = pb[2] - pd[2];
-  cdz = pc[2] - pd[2];
-
-  bdxcdy = bdx * cdy;
-  cdxbdy = cdx * bdy;
-
-  cdxady = cdx * ady;
-  adxcdy = adx * cdy;
-
-  adxbdy = adx * bdy;
-  bdxady = bdx * ady;
-
-  det = adz * (bdxcdy - cdxbdy) 
-      + bdz * (cdxady - adxcdy)
-      + cdz * (adxbdy - bdxady);
-
-  permanent = (Absolute(bdxcdy) + Absolute(cdxbdy)) * Absolute(adz)
-            + (Absolute(cdxady) + Absolute(adxcdy)) * Absolute(bdz)
-            + (Absolute(adxbdy) + Absolute(bdxady)) * Absolute(cdz);
-  errbound = o3derrboundA * permanent;
-  if ((det > errbound) || (-det > errbound)) {
-    FPU_RESTORE;
-    return det;
-  }
-
-  orient = orient3dadapt(pa, pb, pc, pd, permanent);
-  FPU_RESTORE;
-  return orient;
-}
-
-/*****************************************************************************/
-/*                                                                           */
-/*  incirclefast()   Approximate 2D incircle test.  Nonrobust.               */
-/*  incircleexact()   Exact 2D incircle test.  Robust.                       */
-/*  incircleslow()   Another exact 2D incircle test.  Robust.                */
-/*  incircle()   Adaptive exact 2D incircle test.  Robust.                   */
-/*                                                                           */
-/*               Return a positive value if the point pd lies inside the     */
-/*               circle passing through pa, pb, and pc; a negative value if  */
-/*               it lies outside; and zero if the four points are cocircular.*/
-/*               The points pa, pb, and pc must be in counterclockwise       */
-/*               order, or the sign of the result will be reversed.          */
-/*                                                                           */
-/*  Only the first and last routine should be used; the middle two are for   */
-/*  timings.                                                                 */
-/*                                                                           */
-/*  The last three use exact arithmetic to ensure a correct answer.  The     */
-/*  result returned is the determinant of a matrix.  In incircle() only,     */
-/*  this determinant is computed adaptively, in the sense that exact         */
-/*  arithmetic is used only to the degree it is needed to ensure that the    */
-/*  returned value has the correct sign.  Hence, incircle() is usually quite */
-/*  fast, but will run more slowly when the input points are cocircular or   */
-/*  nearly so.                                                               */
-/*                                                                           */
-/*****************************************************************************/
-
-static REAL incircleadapt(REAL *pa, REAL *pb, REAL *pc, REAL *pd, 
-			  REAL permanent)
-{
-  INEXACT REAL adx, bdx, cdx, ady, bdy, cdy;
-  REAL det, errbound;
-
-  INEXACT REAL bdxcdy1, cdxbdy1, cdxady1, adxcdy1, adxbdy1, bdxady1;
-  REAL bdxcdy0, cdxbdy0, cdxady0, adxcdy0, adxbdy0, bdxady0;
-  REAL bc[4], ca[4], ab[4];
-  INEXACT REAL bc3, ca3, ab3;
-  REAL axbc[8], axxbc[16], aybc[8], ayybc[16], adet[32];
-  int axbclen, axxbclen, aybclen, ayybclen, alen;
-  REAL bxca[8], bxxca[16], byca[8], byyca[16], bdet[32];
-  int bxcalen, bxxcalen, bycalen, byycalen, blen;
-  REAL cxab[8], cxxab[16], cyab[8], cyyab[16], cdet[32];
-  int cxablen, cxxablen, cyablen, cyyablen, clen;
-  REAL abdet[64];
-  int ablen;
-  REAL fin1[1152], fin2[1152];
-  REAL *finnow, *finother, *finswap;
-  int finlength;
-
-  REAL adxtail, bdxtail, cdxtail, adytail, bdytail, cdytail;
-  INEXACT REAL adxadx1, adyady1, bdxbdx1, bdybdy1, cdxcdx1, cdycdy1;
-  REAL adxadx0, adyady0, bdxbdx0, bdybdy0, cdxcdx0, cdycdy0;
-  REAL aa[4], bb[4], cc[4];
-  INEXACT REAL aa3, bb3, cc3;
-  INEXACT REAL ti1, tj1;
-  REAL ti0, tj0;
-  REAL u[4], v[4];
-  INEXACT REAL u3, v3;
-  REAL temp8[8], temp16a[16], temp16b[16], temp16c[16];
-  REAL temp32a[32], temp32b[32], temp48[48], temp64[64];
-  int temp8len, temp16alen, temp16blen, temp16clen;
-  int temp32alen, temp32blen, temp48len, temp64len;
-  REAL axtbb[8], axtcc[8], aytbb[8], aytcc[8];
-  int axtbblen, axtcclen, aytbblen, aytcclen;
-  REAL bxtaa[8], bxtcc[8], bytaa[8], bytcc[8];
-  int bxtaalen, bxtcclen, bytaalen, bytcclen;
-  REAL cxtaa[8], cxtbb[8], cytaa[8], cytbb[8];
-  int cxtaalen, cxtbblen, cytaalen, cytbblen;
-  REAL axtbc[8], aytbc[8], bxtca[8], bytca[8], cxtab[8], cytab[8];
-  int axtbclen = 0, aytbclen = 0;
-  int bxtcalen = 0, bytcalen = 0;
-  int cxtablen = 0, cytablen = 0;
-  REAL axtbct[16], aytbct[16], bxtcat[16], bytcat[16], cxtabt[16], cytabt[16];
-  int axtbctlen, aytbctlen, bxtcatlen, bytcatlen, cxtabtlen, cytabtlen;
-  REAL axtbctt[8], aytbctt[8], bxtcatt[8];
-  REAL bytcatt[8], cxtabtt[8], cytabtt[8];
-  int axtbcttlen, aytbcttlen, bxtcattlen, bytcattlen, cxtabttlen, cytabttlen;
-  REAL abt[8], bct[8], cat[8];
-  int abtlen, bctlen, catlen;
-  REAL abtt[4], bctt[4], catt[4];
-  int abttlen, bcttlen, cattlen;
-  INEXACT REAL abtt3, bctt3, catt3;
-  REAL negate;
-
-  INEXACT REAL bvirt;
-  REAL avirt, bround, around;
-  INEXACT REAL c;
-  INEXACT REAL abig;
-  REAL ahi, alo, bhi, blo;
-  REAL err1, err2, err3;
-  INEXACT REAL _i, _j;
-  REAL _0;
-
-  adx = (REAL) (pa[0] - pd[0]);
-  bdx = (REAL) (pb[0] - pd[0]);
-  cdx = (REAL) (pc[0] - pd[0]);
-  ady = (REAL) (pa[1] - pd[1]);
-  bdy = (REAL) (pb[1] - pd[1]);
-  cdy = (REAL) (pc[1] - pd[1]);
-
-  Two_Product(bdx, cdy, bdxcdy1, bdxcdy0);
-  Two_Product(cdx, bdy, cdxbdy1, cdxbdy0);
-  Two_Two_Diff(bdxcdy1, bdxcdy0, cdxbdy1, cdxbdy0, bc3, bc[2], bc[1], bc[0]);
-  bc[3] = bc3;
-  axbclen = scale_expansion_zeroelim(4, bc, adx, axbc);
-  axxbclen = scale_expansion_zeroelim(axbclen, axbc, adx, axxbc);
-  aybclen = scale_expansion_zeroelim(4, bc, ady, aybc);
-  ayybclen = scale_expansion_zeroelim(aybclen, aybc, ady, ayybc);
-  alen = fast_expansion_sum_zeroelim(axxbclen, axxbc, ayybclen, ayybc, adet);
-
-  Two_Product(cdx, ady, cdxady1, cdxady0);
-  Two_Product(adx, cdy, adxcdy1, adxcdy0);
-  Two_Two_Diff(cdxady1, cdxady0, adxcdy1, adxcdy0, ca3, ca[2], ca[1], ca[0]);
-  ca[3] = ca3;
-  bxcalen = scale_expansion_zeroelim(4, ca, bdx, bxca);
-  bxxcalen = scale_expansion_zeroelim(bxcalen, bxca, bdx, bxxca);
-  bycalen = scale_expansion_zeroelim(4, ca, bdy, byca);
-  byycalen = scale_expansion_zeroelim(bycalen, byca, bdy, byyca);
-  blen = fast_expansion_sum_zeroelim(bxxcalen, bxxca, byycalen, byyca, bdet);
-
-  Two_Product(adx, bdy, adxbdy1, adxbdy0);
-  Two_Product(bdx, ady, bdxady1, bdxady0);
-  Two_Two_Diff(adxbdy1, adxbdy0, bdxady1, bdxady0, ab3, ab[2], ab[1], ab[0]);
-  ab[3] = ab3;
-  cxablen = scale_expansion_zeroelim(4, ab, cdx, cxab);
-  cxxablen = scale_expansion_zeroelim(cxablen, cxab, cdx, cxxab);
-  cyablen = scale_expansion_zeroelim(4, ab, cdy, cyab);
-  cyyablen = scale_expansion_zeroelim(cyablen, cyab, cdy, cyyab);
-  clen = fast_expansion_sum_zeroelim(cxxablen, cxxab, cyyablen, cyyab, cdet);
-
-  ablen = fast_expansion_sum_zeroelim(alen, adet, blen, bdet, abdet);
-  finlength = fast_expansion_sum_zeroelim(ablen, abdet, clen, cdet, fin1);
-
-  det = estimate(finlength, fin1);
-  errbound = iccerrboundB * permanent;
-  if ((det >= errbound) || (-det >= errbound)) {
-    return det;
-  }
-
-  Two_Diff_Tail(pa[0], pd[0], adx, adxtail);
-  Two_Diff_Tail(pa[1], pd[1], ady, adytail);
-  Two_Diff_Tail(pb[0], pd[0], bdx, bdxtail);
-  Two_Diff_Tail(pb[1], pd[1], bdy, bdytail);
-  Two_Diff_Tail(pc[0], pd[0], cdx, cdxtail);
-  Two_Diff_Tail(pc[1], pd[1], cdy, cdytail);
-  if ((adxtail == 0.0) && (bdxtail == 0.0) && (cdxtail == 0.0)
-      && (adytail == 0.0) && (bdytail == 0.0) && (cdytail == 0.0)) {
-    return det;
-  }
-
-  errbound = iccerrboundC * permanent + resulterrbound * Absolute(det);
-  det += ((adx * adx + ady * ady) * ((bdx * cdytail + cdy * bdxtail)
-                                     - (bdy * cdxtail + cdx * bdytail))
-          + 2.0 * (adx * adxtail + ady * adytail) * (bdx * cdy - bdy * cdx))
-       + ((bdx * bdx + bdy * bdy) * ((cdx * adytail + ady * cdxtail)
-                                     - (cdy * adxtail + adx * cdytail))
-          + 2.0 * (bdx * bdxtail + bdy * bdytail) * (cdx * ady - cdy * adx))
-       + ((cdx * cdx + cdy * cdy) * ((adx * bdytail + bdy * adxtail)
-                                     - (ady * bdxtail + bdx * adytail))
-          + 2.0 * (cdx * cdxtail + cdy * cdytail) * (adx * bdy - ady * bdx));
-  if ((det >= errbound) || (-det >= errbound)) {
-    return det;
-  }
-
-  finnow = fin1;
-  finother = fin2;
-
-  if ((bdxtail != 0.0) || (bdytail != 0.0)
-      || (cdxtail != 0.0) || (cdytail != 0.0)) {
-    Square(adx, adxadx1, adxadx0);
-    Square(ady, adyady1, adyady0);
-    Two_Two_Sum(adxadx1, adxadx0, adyady1, adyady0, aa3, aa[2], aa[1], aa[0]);
-    aa[3] = aa3;
-  }
-  if ((cdxtail != 0.0) || (cdytail != 0.0)
-      || (adxtail != 0.0) || (adytail != 0.0)) {
-    Square(bdx, bdxbdx1, bdxbdx0);
-    Square(bdy, bdybdy1, bdybdy0);
-    Two_Two_Sum(bdxbdx1, bdxbdx0, bdybdy1, bdybdy0, bb3, bb[2], bb[1], bb[0]);
-    bb[3] = bb3;
-  }
-  if ((adxtail != 0.0) || (adytail != 0.0)
-      || (bdxtail != 0.0) || (bdytail != 0.0)) {
-    Square(cdx, cdxcdx1, cdxcdx0);
-    Square(cdy, cdycdy1, cdycdy0);
-    Two_Two_Sum(cdxcdx1, cdxcdx0, cdycdy1, cdycdy0, cc3, cc[2], cc[1], cc[0]);
-    cc[3] = cc3;
-  }
-
-  if (adxtail != 0.0) {
-    axtbclen = scale_expansion_zeroelim(4, bc, adxtail, axtbc);
-    temp16alen = scale_expansion_zeroelim(axtbclen, axtbc, 2.0 * adx,
-                                          temp16a);
-
-    axtcclen = scale_expansion_zeroelim(4, cc, adxtail, axtcc);
-    temp16blen = scale_expansion_zeroelim(axtcclen, axtcc, bdy, temp16b);
-
-    axtbblen = scale_expansion_zeroelim(4, bb, adxtail, axtbb);
-    temp16clen = scale_expansion_zeroelim(axtbblen, axtbb, -cdy, temp16c);
-
-    temp32alen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                            temp16blen, temp16b, temp32a);
-    temp48len = fast_expansion_sum_zeroelim(temp16clen, temp16c,
-                                            temp32alen, temp32a, temp48);
-    finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
-                                            temp48, finother);
-    finswap = finnow; finnow = finother; finother = finswap;
-  }
-  if (adytail != 0.0) {
-    aytbclen = scale_expansion_zeroelim(4, bc, adytail, aytbc);
-    temp16alen = scale_expansion_zeroelim(aytbclen, aytbc, 2.0 * ady,
-                                          temp16a);
-
-    aytbblen = scale_expansion_zeroelim(4, bb, adytail, aytbb);
-    temp16blen = scale_expansion_zeroelim(aytbblen, aytbb, cdx, temp16b);
-
-    aytcclen = scale_expansion_zeroelim(4, cc, adytail, aytcc);
-    temp16clen = scale_expansion_zeroelim(aytcclen, aytcc, -bdx, temp16c);
-
-    temp32alen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                            temp16blen, temp16b, temp32a);
-    temp48len = fast_expansion_sum_zeroelim(temp16clen, temp16c,
-                                            temp32alen, temp32a, temp48);
-    finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
-                                            temp48, finother);
-    finswap = finnow; finnow = finother; finother = finswap;
-  }
-  if (bdxtail != 0.0) {
-    bxtcalen = scale_expansion_zeroelim(4, ca, bdxtail, bxtca);
-    temp16alen = scale_expansion_zeroelim(bxtcalen, bxtca, 2.0 * bdx,
-                                          temp16a);
-
-    bxtaalen = scale_expansion_zeroelim(4, aa, bdxtail, bxtaa);
-    temp16blen = scale_expansion_zeroelim(bxtaalen, bxtaa, cdy, temp16b);
-
-    bxtcclen = scale_expansion_zeroelim(4, cc, bdxtail, bxtcc);
-    temp16clen = scale_expansion_zeroelim(bxtcclen, bxtcc, -ady, temp16c);
-
-    temp32alen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                            temp16blen, temp16b, temp32a);
-    temp48len = fast_expansion_sum_zeroelim(temp16clen, temp16c,
-                                            temp32alen, temp32a, temp48);
-    finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
-                                            temp48, finother);
-    finswap = finnow; finnow = finother; finother = finswap;
-  }
-  if (bdytail != 0.0) {
-    bytcalen = scale_expansion_zeroelim(4, ca, bdytail, bytca);
-    temp16alen = scale_expansion_zeroelim(bytcalen, bytca, 2.0 * bdy,
-                                          temp16a);
-
-    bytcclen = scale_expansion_zeroelim(4, cc, bdytail, bytcc);
-    temp16blen = scale_expansion_zeroelim(bytcclen, bytcc, adx, temp16b);
-
-    bytaalen = scale_expansion_zeroelim(4, aa, bdytail, bytaa);
-    temp16clen = scale_expansion_zeroelim(bytaalen, bytaa, -cdx, temp16c);
-
-    temp32alen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                            temp16blen, temp16b, temp32a);
-    temp48len = fast_expansion_sum_zeroelim(temp16clen, temp16c,
-                                            temp32alen, temp32a, temp48);
-    finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
-                                            temp48, finother);
-    finswap = finnow; finnow = finother; finother = finswap;
-  }
-  if (cdxtail != 0.0) {
-    cxtablen = scale_expansion_zeroelim(4, ab, cdxtail, cxtab);
-    temp16alen = scale_expansion_zeroelim(cxtablen, cxtab, 2.0 * cdx,
-                                          temp16a);
-
-    cxtbblen = scale_expansion_zeroelim(4, bb, cdxtail, cxtbb);
-    temp16blen = scale_expansion_zeroelim(cxtbblen, cxtbb, ady, temp16b);
-
-    cxtaalen = scale_expansion_zeroelim(4, aa, cdxtail, cxtaa);
-    temp16clen = scale_expansion_zeroelim(cxtaalen, cxtaa, -bdy, temp16c);
-
-    temp32alen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                            temp16blen, temp16b, temp32a);
-    temp48len = fast_expansion_sum_zeroelim(temp16clen, temp16c,
-                                            temp32alen, temp32a, temp48);
-    finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
-                                            temp48, finother);
-    finswap = finnow; finnow = finother; finother = finswap;
-  }
-  if (cdytail != 0.0) {
-    cytablen = scale_expansion_zeroelim(4, ab, cdytail, cytab);
-    temp16alen = scale_expansion_zeroelim(cytablen, cytab, 2.0 * cdy,
-                                          temp16a);
-
-    cytaalen = scale_expansion_zeroelim(4, aa, cdytail, cytaa);
-    temp16blen = scale_expansion_zeroelim(cytaalen, cytaa, bdx, temp16b);
-
-    cytbblen = scale_expansion_zeroelim(4, bb, cdytail, cytbb);
-    temp16clen = scale_expansion_zeroelim(cytbblen, cytbb, -adx, temp16c);
-
-    temp32alen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                            temp16blen, temp16b, temp32a);
-    temp48len = fast_expansion_sum_zeroelim(temp16clen, temp16c,
-                                            temp32alen, temp32a, temp48);
-    finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
-                                            temp48, finother);
-    finswap = finnow; finnow = finother; finother = finswap;
-  }
-
-  if ((adxtail != 0.0) || (adytail != 0.0)) {
-    if ((bdxtail != 0.0) || (bdytail != 0.0)
-        || (cdxtail != 0.0) || (cdytail != 0.0)) {
-      Two_Product(bdxtail, cdy, ti1, ti0);
-      Two_Product(bdx, cdytail, tj1, tj0);
-      Two_Two_Sum(ti1, ti0, tj1, tj0, u3, u[2], u[1], u[0]);
-      u[3] = u3;
-      negate = -bdy;
-      Two_Product(cdxtail, negate, ti1, ti0);
-      negate = -bdytail;
-      Two_Product(cdx, negate, tj1, tj0);
-      Two_Two_Sum(ti1, ti0, tj1, tj0, v3, v[2], v[1], v[0]);
-      v[3] = v3;
-      bctlen = fast_expansion_sum_zeroelim(4, u, 4, v, bct);
-
-      Two_Product(bdxtail, cdytail, ti1, ti0);
-      Two_Product(cdxtail, bdytail, tj1, tj0);
-      Two_Two_Diff(ti1, ti0, tj1, tj0, bctt3, bctt[2], bctt[1], bctt[0]);
-      bctt[3] = bctt3;
-      bcttlen = 4;
-    } else {
-      bct[0] = 0.0;
-      bctlen = 1;
-      bctt[0] = 0.0;
-      bcttlen = 1;
-    }
-
-    if (adxtail != 0.0) {
-      temp16alen = scale_expansion_zeroelim(axtbclen, axtbc, adxtail, temp16a);
-      axtbctlen = scale_expansion_zeroelim(bctlen, bct, adxtail, axtbct);
-      temp32alen = scale_expansion_zeroelim(axtbctlen, axtbct, 2.0 * adx,
-                                            temp32a);
-      temp48len = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                              temp32alen, temp32a, temp48);
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
-                                              temp48, finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-      if (bdytail != 0.0) {
-        temp8len = scale_expansion_zeroelim(4, cc, adxtail, temp8);
-        temp16alen = scale_expansion_zeroelim(temp8len, temp8, bdytail,
-                                              temp16a);
-        finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp16alen,
-                                                temp16a, finother);
-        finswap = finnow; finnow = finother; finother = finswap;
-      }
-      if (cdytail != 0.0) {
-        temp8len = scale_expansion_zeroelim(4, bb, -adxtail, temp8);
-        temp16alen = scale_expansion_zeroelim(temp8len, temp8, cdytail,
-                                              temp16a);
-        finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp16alen,
-                                                temp16a, finother);
-        finswap = finnow; finnow = finother; finother = finswap;
-      }
-
-      temp32alen = scale_expansion_zeroelim(axtbctlen, axtbct, adxtail,
-                                            temp32a);
-      axtbcttlen = scale_expansion_zeroelim(bcttlen, bctt, adxtail, axtbctt);
-      temp16alen = scale_expansion_zeroelim(axtbcttlen, axtbctt, 2.0 * adx,
-                                            temp16a);
-      temp16blen = scale_expansion_zeroelim(axtbcttlen, axtbctt, adxtail,
-                                            temp16b);
-      temp32blen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                              temp16blen, temp16b, temp32b);
-      temp64len = fast_expansion_sum_zeroelim(temp32alen, temp32a,
-                                              temp32blen, temp32b, temp64);
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp64len,
-                                              temp64, finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-    }
-    if (adytail != 0.0) {
-      temp16alen = scale_expansion_zeroelim(aytbclen, aytbc, adytail, temp16a);
-      aytbctlen = scale_expansion_zeroelim(bctlen, bct, adytail, aytbct);
-      temp32alen = scale_expansion_zeroelim(aytbctlen, aytbct, 2.0 * ady,
-                                            temp32a);
-      temp48len = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                              temp32alen, temp32a, temp48);
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
-                                              temp48, finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-
-
-      temp32alen = scale_expansion_zeroelim(aytbctlen, aytbct, adytail,
-                                            temp32a);
-      aytbcttlen = scale_expansion_zeroelim(bcttlen, bctt, adytail, aytbctt);
-      temp16alen = scale_expansion_zeroelim(aytbcttlen, aytbctt, 2.0 * ady,
-                                            temp16a);
-      temp16blen = scale_expansion_zeroelim(aytbcttlen, aytbctt, adytail,
-                                            temp16b);
-      temp32blen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                              temp16blen, temp16b, temp32b);
-      temp64len = fast_expansion_sum_zeroelim(temp32alen, temp32a,
-                                              temp32blen, temp32b, temp64);
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp64len,
-                                              temp64, finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-    }
-  }
-  if ((bdxtail != 0.0) || (bdytail != 0.0)) {
-    if ((cdxtail != 0.0) || (cdytail != 0.0)
-        || (adxtail != 0.0) || (adytail != 0.0)) {
-      Two_Product(cdxtail, ady, ti1, ti0);
-      Two_Product(cdx, adytail, tj1, tj0);
-      Two_Two_Sum(ti1, ti0, tj1, tj0, u3, u[2], u[1], u[0]);
-      u[3] = u3;
-      negate = -cdy;
-      Two_Product(adxtail, negate, ti1, ti0);
-      negate = -cdytail;
-      Two_Product(adx, negate, tj1, tj0);
-      Two_Two_Sum(ti1, ti0, tj1, tj0, v3, v[2], v[1], v[0]);
-      v[3] = v3;
-      catlen = fast_expansion_sum_zeroelim(4, u, 4, v, cat);
-
-      Two_Product(cdxtail, adytail, ti1, ti0);
-      Two_Product(adxtail, cdytail, tj1, tj0);
-      Two_Two_Diff(ti1, ti0, tj1, tj0, catt3, catt[2], catt[1], catt[0]);
-      catt[3] = catt3;
-      cattlen = 4;
-    } else {
-      cat[0] = 0.0;
-      catlen = 1;
-      catt[0] = 0.0;
-      cattlen = 1;
-    }
-
-    if (bdxtail != 0.0) {
-      temp16alen = scale_expansion_zeroelim(bxtcalen, bxtca, bdxtail, temp16a);
-      bxtcatlen = scale_expansion_zeroelim(catlen, cat, bdxtail, bxtcat);
-      temp32alen = scale_expansion_zeroelim(bxtcatlen, bxtcat, 2.0 * bdx,
-                                            temp32a);
-      temp48len = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                              temp32alen, temp32a, temp48);
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
-                                              temp48, finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-      if (cdytail != 0.0) {
-        temp8len = scale_expansion_zeroelim(4, aa, bdxtail, temp8);
-        temp16alen = scale_expansion_zeroelim(temp8len, temp8, cdytail,
-                                              temp16a);
-        finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp16alen,
-                                                temp16a, finother);
-        finswap = finnow; finnow = finother; finother = finswap;
-      }
-      if (adytail != 0.0) {
-        temp8len = scale_expansion_zeroelim(4, cc, -bdxtail, temp8);
-        temp16alen = scale_expansion_zeroelim(temp8len, temp8, adytail,
-                                              temp16a);
-        finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp16alen,
-                                                temp16a, finother);
-        finswap = finnow; finnow = finother; finother = finswap;
-      }
-
-      temp32alen = scale_expansion_zeroelim(bxtcatlen, bxtcat, bdxtail,
-                                            temp32a);
-      bxtcattlen = scale_expansion_zeroelim(cattlen, catt, bdxtail, bxtcatt);
-      temp16alen = scale_expansion_zeroelim(bxtcattlen, bxtcatt, 2.0 * bdx,
-                                            temp16a);
-      temp16blen = scale_expansion_zeroelim(bxtcattlen, bxtcatt, bdxtail,
-                                            temp16b);
-      temp32blen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                              temp16blen, temp16b, temp32b);
-      temp64len = fast_expansion_sum_zeroelim(temp32alen, temp32a,
-                                              temp32blen, temp32b, temp64);
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp64len,
-                                              temp64, finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-    }
-    if (bdytail != 0.0) {
-      temp16alen = scale_expansion_zeroelim(bytcalen, bytca, bdytail, temp16a);
-      bytcatlen = scale_expansion_zeroelim(catlen, cat, bdytail, bytcat);
-      temp32alen = scale_expansion_zeroelim(bytcatlen, bytcat, 2.0 * bdy,
-                                            temp32a);
-      temp48len = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                              temp32alen, temp32a, temp48);
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
-                                              temp48, finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-
-
-      temp32alen = scale_expansion_zeroelim(bytcatlen, bytcat, bdytail,
-                                            temp32a);
-      bytcattlen = scale_expansion_zeroelim(cattlen, catt, bdytail, bytcatt);
-      temp16alen = scale_expansion_zeroelim(bytcattlen, bytcatt, 2.0 * bdy,
-                                            temp16a);
-      temp16blen = scale_expansion_zeroelim(bytcattlen, bytcatt, bdytail,
-                                            temp16b);
-      temp32blen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                              temp16blen, temp16b, temp32b);
-      temp64len = fast_expansion_sum_zeroelim(temp32alen, temp32a,
-                                              temp32blen, temp32b, temp64);
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp64len,
-                                              temp64, finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-    }
-  }
-  if ((cdxtail != 0.0) || (cdytail != 0.0)) {
-    if ((adxtail != 0.0) || (adytail != 0.0)
-        || (bdxtail != 0.0) || (bdytail != 0.0)) {
-      Two_Product(adxtail, bdy, ti1, ti0);
-      Two_Product(adx, bdytail, tj1, tj0);
-      Two_Two_Sum(ti1, ti0, tj1, tj0, u3, u[2], u[1], u[0]);
-      u[3] = u3;
-      negate = -ady;
-      Two_Product(bdxtail, negate, ti1, ti0);
-      negate = -adytail;
-      Two_Product(bdx, negate, tj1, tj0);
-      Two_Two_Sum(ti1, ti0, tj1, tj0, v3, v[2], v[1], v[0]);
-      v[3] = v3;
-      abtlen = fast_expansion_sum_zeroelim(4, u, 4, v, abt);
-
-      Two_Product(adxtail, bdytail, ti1, ti0);
-      Two_Product(bdxtail, adytail, tj1, tj0);
-      Two_Two_Diff(ti1, ti0, tj1, tj0, abtt3, abtt[2], abtt[1], abtt[0]);
-      abtt[3] = abtt3;
-      abttlen = 4;
-    } else {
-      abt[0] = 0.0;
-      abtlen = 1;
-      abtt[0] = 0.0;
-      abttlen = 1;
-    }
-
-    if (cdxtail != 0.0) {
-      temp16alen = scale_expansion_zeroelim(cxtablen, cxtab, cdxtail, temp16a);
-      cxtabtlen = scale_expansion_zeroelim(abtlen, abt, cdxtail, cxtabt);
-      temp32alen = scale_expansion_zeroelim(cxtabtlen, cxtabt, 2.0 * cdx,
-                                            temp32a);
-      temp48len = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                              temp32alen, temp32a, temp48);
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
-                                              temp48, finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-      if (adytail != 0.0) {
-        temp8len = scale_expansion_zeroelim(4, bb, cdxtail, temp8);
-        temp16alen = scale_expansion_zeroelim(temp8len, temp8, adytail,
-                                              temp16a);
-        finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp16alen,
-                                                temp16a, finother);
-        finswap = finnow; finnow = finother; finother = finswap;
-      }
-      if (bdytail != 0.0) {
-        temp8len = scale_expansion_zeroelim(4, aa, -cdxtail, temp8);
-        temp16alen = scale_expansion_zeroelim(temp8len, temp8, bdytail,
-                                              temp16a);
-        finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp16alen,
-                                                temp16a, finother);
-        finswap = finnow; finnow = finother; finother = finswap;
-      }
-
-      temp32alen = scale_expansion_zeroelim(cxtabtlen, cxtabt, cdxtail,
-                                            temp32a);
-      cxtabttlen = scale_expansion_zeroelim(abttlen, abtt, cdxtail, cxtabtt);
-      temp16alen = scale_expansion_zeroelim(cxtabttlen, cxtabtt, 2.0 * cdx,
-                                            temp16a);
-      temp16blen = scale_expansion_zeroelim(cxtabttlen, cxtabtt, cdxtail,
-                                            temp16b);
-      temp32blen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                              temp16blen, temp16b, temp32b);
-      temp64len = fast_expansion_sum_zeroelim(temp32alen, temp32a,
-                                              temp32blen, temp32b, temp64);
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp64len,
-                                              temp64, finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-    }
-    if (cdytail != 0.0) {
-      temp16alen = scale_expansion_zeroelim(cytablen, cytab, cdytail, temp16a);
-      cytabtlen = scale_expansion_zeroelim(abtlen, abt, cdytail, cytabt);
-      temp32alen = scale_expansion_zeroelim(cytabtlen, cytabt, 2.0 * cdy,
-                                            temp32a);
-      temp48len = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                              temp32alen, temp32a, temp48);
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp48len,
-                                              temp48, finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-
-
-      temp32alen = scale_expansion_zeroelim(cytabtlen, cytabt, cdytail,
-                                            temp32a);
-      cytabttlen = scale_expansion_zeroelim(abttlen, abtt, cdytail, cytabtt);
-      temp16alen = scale_expansion_zeroelim(cytabttlen, cytabtt, 2.0 * cdy,
-                                            temp16a);
-      temp16blen = scale_expansion_zeroelim(cytabttlen, cytabtt, cdytail,
-                                            temp16b);
-      temp32blen = fast_expansion_sum_zeroelim(temp16alen, temp16a,
-                                              temp16blen, temp16b, temp32b);
-      temp64len = fast_expansion_sum_zeroelim(temp32alen, temp32a,
-                                              temp32blen, temp32b, temp64);
-      finlength = fast_expansion_sum_zeroelim(finlength, finnow, temp64len,
-                                              temp64, finother);
-      finswap = finnow; finnow = finother; finother = finswap;
-    }
-  }
-
-  return finnow[finlength - 1];
-}
-
-REAL incircle(pa, pb, pc, pd)
-REAL *pa;
-REAL *pb;
-REAL *pc;
-REAL *pd;
-{
-  REAL adx, bdx, cdx, ady, bdy, cdy;
-  REAL bdxcdy, cdxbdy, cdxady, adxcdy, adxbdy, bdxady;
-  REAL alift, blift, clift;
-  REAL det;
-  REAL permanent, errbound;
-  REAL inc;
-
-  FPU_ROUND_DOUBLE;
-  
-  adx = pa[0] - pd[0];
-  bdx = pb[0] - pd[0];
-  cdx = pc[0] - pd[0];
-  ady = pa[1] - pd[1];
-  bdy = pb[1] - pd[1];
-  cdy = pc[1] - pd[1];
-
-  bdxcdy = bdx * cdy;
-  cdxbdy = cdx * bdy;
-  alift = adx * adx + ady * ady;
-
-  cdxady = cdx * ady;
-  adxcdy = adx * cdy;
-  blift = bdx * bdx + bdy * bdy;
-
-  adxbdy = adx * bdy;
-  bdxady = bdx * ady;
-  clift = cdx * cdx + cdy * cdy;
-
-  det = alift * (bdxcdy - cdxbdy)
-      + blift * (cdxady - adxcdy)
-      + clift * (adxbdy - bdxady);
-
-  permanent = (Absolute(bdxcdy) + Absolute(cdxbdy)) * alift
-            + (Absolute(cdxady) + Absolute(adxcdy)) * blift
-            + (Absolute(adxbdy) + Absolute(bdxady)) * clift;
-  errbound = iccerrboundA * permanent;
-  if ((det > errbound) || (-det > errbound)) {
-    FPU_RESTORE;
-    return det;
-  }
-
-  inc = incircleadapt(pa, pb, pc, pd, permanent);
-  FPU_RESTORE;
-  return inc;
-}
-
-/*****************************************************************************/
-/*                                                                           */
-/*  inspherefast()   Approximate 3D insphere test.  Nonrobust.               */
-/*  insphereexact()   Exact 3D insphere test.  Robust.                       */
-/*  insphereslow()   Another exact 3D insphere test.  Robust.                */
-/*  insphere()   Adaptive exact 3D insphere test.  Robust.                   */
-/*                                                                           */
-/*               Return a positive value if the point pe lies inside the     */
-/*               sphere passing through pa, pb, pc, and pd; a negative value */
-/*               if it lies outside; and zero if the five points are         */
-/*               cospherical.  The points pa, pb, pc, and pd must be ordered */
-/*               so that they have a positive orientation (as defined by     */
-/*               orient3d()), or the sign of the result will be reversed.    */
-/*                                                                           */
-/*  Only the first and last routine should be used; the middle two are for   */
-/*  timings.                                                                 */
-/*                                                                           */
-/*  The last three use exact arithmetic to ensure a correct answer.  The     */
-/*  result returned is the determinant of a matrix.  In insphere() only,     */
-/*  this determinant is computed adaptively, in the sense that exact         */
-/*  arithmetic is used only to the degree it is needed to ensure that the    */
-/*  returned value has the correct sign.  Hence, insphere() is usually quite */
-/*  fast, but will run more slowly when the input points are cospherical or  */
-/*  nearly so.                                                               */
-/*                                                                           */
-/*****************************************************************************/
-
-static REAL insphereexact(REAL *pa, REAL *pb, REAL *pc, REAL *pd, REAL *pe)
-{
-  INEXACT REAL axby1, bxcy1, cxdy1, dxey1, exay1;
-  INEXACT REAL bxay1, cxby1, dxcy1, exdy1, axey1;
-  INEXACT REAL axcy1, bxdy1, cxey1, dxay1, exby1;
-  INEXACT REAL cxay1, dxby1, excy1, axdy1, bxey1;
-  REAL axby0, bxcy0, cxdy0, dxey0, exay0;
-  REAL bxay0, cxby0, dxcy0, exdy0, axey0;
-  REAL axcy0, bxdy0, cxey0, dxay0, exby0;
-  REAL cxay0, dxby0, excy0, axdy0, bxey0;
-  REAL ab[4], bc[4], cd[4], de[4], ea[4];
-  REAL ac[4], bd[4], ce[4], da[4], eb[4];
-  REAL temp8a[8], temp8b[8], temp16[16];
-  int temp8alen, temp8blen, temp16len;
-  REAL abc[24], bcd[24], cde[24], dea[24], eab[24];
-  REAL abd[24], bce[24], cda[24], deb[24], eac[24];
-  int abclen, bcdlen, cdelen, dealen, eablen;
-  int abdlen, bcelen, cdalen, deblen, eaclen;
-  REAL temp48a[48], temp48b[48];
-  int temp48alen, temp48blen;
-  REAL abcd[96], bcde[96], cdea[96], deab[96], eabc[96];
-  int abcdlen, bcdelen, cdealen, deablen, eabclen;
-  REAL temp192[192];
-  REAL det384x[384], det384y[384], det384z[384];
-  int xlen, ylen, zlen;
-  REAL detxy[768];
-  int xylen;
-  REAL adet[1152], bdet[1152], cdet[1152], ddet[1152], edet[1152];
-  int alen, blen, clen, dlen, elen;
-  REAL abdet[2304], cddet[2304], cdedet[3456];
-  int ablen, cdlen;
-  REAL deter[5760];
-  int deterlen;
-  int i;
-
-  INEXACT REAL bvirt;
-  REAL avirt, bround, around;
-  INEXACT REAL c;
-  INEXACT REAL abig;
-  REAL ahi, alo, bhi, blo;
-  REAL err1, err2, err3;
-  INEXACT REAL _i, _j;
-  REAL _0;
-
-  Two_Product(pa[0], pb[1], axby1, axby0);
-  Two_Product(pb[0], pa[1], bxay1, bxay0);
-  Two_Two_Diff(axby1, axby0, bxay1, bxay0, ab[3], ab[2], ab[1], ab[0]);
-
-  Two_Product(pb[0], pc[1], bxcy1, bxcy0);
-  Two_Product(pc[0], pb[1], cxby1, cxby0);
-  Two_Two_Diff(bxcy1, bxcy0, cxby1, cxby0, bc[3], bc[2], bc[1], bc[0]);
-
-  Two_Product(pc[0], pd[1], cxdy1, cxdy0);
-  Two_Product(pd[0], pc[1], dxcy1, dxcy0);
-  Two_Two_Diff(cxdy1, cxdy0, dxcy1, dxcy0, cd[3], cd[2], cd[1], cd[0]);
-
-  Two_Product(pd[0], pe[1], dxey1, dxey0);
-  Two_Product(pe[0], pd[1], exdy1, exdy0);
-  Two_Two_Diff(dxey1, dxey0, exdy1, exdy0, de[3], de[2], de[1], de[0]);
-
-  Two_Product(pe[0], pa[1], exay1, exay0);
-  Two_Product(pa[0], pe[1], axey1, axey0);
-  Two_Two_Diff(exay1, exay0, axey1, axey0, ea[3], ea[2], ea[1], ea[0]);
-
-  Two_Product(pa[0], pc[1], axcy1, axcy0);
-  Two_Product(pc[0], pa[1], cxay1, cxay0);
-  Two_Two_Diff(axcy1, axcy0, cxay1, cxay0, ac[3], ac[2], ac[1], ac[0]);
-
-  Two_Product(pb[0], pd[1], bxdy1, bxdy0);
-  Two_Product(pd[0], pb[1], dxby1, dxby0);
-  Two_Two_Diff(bxdy1, bxdy0, dxby1, dxby0, bd[3], bd[2], bd[1], bd[0]);
-
-  Two_Product(pc[0], pe[1], cxey1, cxey0);
-  Two_Product(pe[0], pc[1], excy1, excy0);
-  Two_Two_Diff(cxey1, cxey0, excy1, excy0, ce[3], ce[2], ce[1], ce[0]);
-
-  Two_Product(pd[0], pa[1], dxay1, dxay0);
-  Two_Product(pa[0], pd[1], axdy1, axdy0);
-  Two_Two_Diff(dxay1, dxay0, axdy1, axdy0, da[3], da[2], da[1], da[0]);
-
-  Two_Product(pe[0], pb[1], exby1, exby0);
-  Two_Product(pb[0], pe[1], bxey1, bxey0);
-  Two_Two_Diff(exby1, exby0, bxey1, bxey0, eb[3], eb[2], eb[1], eb[0]);
-
-  temp8alen = scale_expansion_zeroelim(4, bc, pa[2], temp8a);
-  temp8blen = scale_expansion_zeroelim(4, ac, -pb[2], temp8b);
-  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
-                                          temp16);
-  temp8alen = scale_expansion_zeroelim(4, ab, pc[2], temp8a);
-  abclen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
-                                       abc);
-
-  temp8alen = scale_expansion_zeroelim(4, cd, pb[2], temp8a);
-  temp8blen = scale_expansion_zeroelim(4, bd, -pc[2], temp8b);
-  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
-                                          temp16);
-  temp8alen = scale_expansion_zeroelim(4, bc, pd[2], temp8a);
-  bcdlen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
-                                       bcd);
-
-  temp8alen = scale_expansion_zeroelim(4, de, pc[2], temp8a);
-  temp8blen = scale_expansion_zeroelim(4, ce, -pd[2], temp8b);
-  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
-                                          temp16);
-  temp8alen = scale_expansion_zeroelim(4, cd, pe[2], temp8a);
-  cdelen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
-                                       cde);
-
-  temp8alen = scale_expansion_zeroelim(4, ea, pd[2], temp8a);
-  temp8blen = scale_expansion_zeroelim(4, da, -pe[2], temp8b);
-  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
-                                          temp16);
-  temp8alen = scale_expansion_zeroelim(4, de, pa[2], temp8a);
-  dealen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
-                                       dea);
-
-  temp8alen = scale_expansion_zeroelim(4, ab, pe[2], temp8a);
-  temp8blen = scale_expansion_zeroelim(4, eb, -pa[2], temp8b);
-  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
-                                          temp16);
-  temp8alen = scale_expansion_zeroelim(4, ea, pb[2], temp8a);
-  eablen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
-                                       eab);
-
-  temp8alen = scale_expansion_zeroelim(4, bd, pa[2], temp8a);
-  temp8blen = scale_expansion_zeroelim(4, da, pb[2], temp8b);
-  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
-                                          temp16);
-  temp8alen = scale_expansion_zeroelim(4, ab, pd[2], temp8a);
-  abdlen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
-                                       abd);
-
-  temp8alen = scale_expansion_zeroelim(4, ce, pb[2], temp8a);
-  temp8blen = scale_expansion_zeroelim(4, eb, pc[2], temp8b);
-  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
-                                          temp16);
-  temp8alen = scale_expansion_zeroelim(4, bc, pe[2], temp8a);
-  bcelen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
-                                       bce);
-
-  temp8alen = scale_expansion_zeroelim(4, da, pc[2], temp8a);
-  temp8blen = scale_expansion_zeroelim(4, ac, pd[2], temp8b);
-  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
-                                          temp16);
-  temp8alen = scale_expansion_zeroelim(4, cd, pa[2], temp8a);
-  cdalen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
-                                       cda);
-
-  temp8alen = scale_expansion_zeroelim(4, eb, pd[2], temp8a);
-  temp8blen = scale_expansion_zeroelim(4, bd, pe[2], temp8b);
-  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
-                                          temp16);
-  temp8alen = scale_expansion_zeroelim(4, de, pb[2], temp8a);
-  deblen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
-                                       deb);
-
-  temp8alen = scale_expansion_zeroelim(4, ac, pe[2], temp8a);
-  temp8blen = scale_expansion_zeroelim(4, ce, pa[2], temp8b);
-  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp8blen, temp8b,
-                                          temp16);
-  temp8alen = scale_expansion_zeroelim(4, ea, pc[2], temp8a);
-  eaclen = fast_expansion_sum_zeroelim(temp8alen, temp8a, temp16len, temp16,
-                                       eac);
-
-  temp48alen = fast_expansion_sum_zeroelim(cdelen, cde, bcelen, bce, temp48a);
-  temp48blen = fast_expansion_sum_zeroelim(deblen, deb, bcdlen, bcd, temp48b);
-  for (i = 0; i < temp48blen; i++) {
-    temp48b[i] = -temp48b[i];
-  }
-  bcdelen = fast_expansion_sum_zeroelim(temp48alen, temp48a,
-                                        temp48blen, temp48b, bcde);
-  xlen = scale_expansion_zeroelim(bcdelen, bcde, pa[0], temp192);
-  xlen = scale_expansion_zeroelim(xlen, temp192, pa[0], det384x);
-  ylen = scale_expansion_zeroelim(bcdelen, bcde, pa[1], temp192);
-  ylen = scale_expansion_zeroelim(ylen, temp192, pa[1], det384y);
-  zlen = scale_expansion_zeroelim(bcdelen, bcde, pa[2], temp192);
-  zlen = scale_expansion_zeroelim(zlen, temp192, pa[2], det384z);
-  xylen = fast_expansion_sum_zeroelim(xlen, det384x, ylen, det384y, detxy);
-  alen = fast_expansion_sum_zeroelim(xylen, detxy, zlen, det384z, adet);
-
-  temp48alen = fast_expansion_sum_zeroelim(dealen, dea, cdalen, cda, temp48a);
-  temp48blen = fast_expansion_sum_zeroelim(eaclen, eac, cdelen, cde, temp48b);
-  for (i = 0; i < temp48blen; i++) {
-    temp48b[i] = -temp48b[i];
-  }
-  cdealen = fast_expansion_sum_zeroelim(temp48alen, temp48a,
-                                        temp48blen, temp48b, cdea);
-  xlen = scale_expansion_zeroelim(cdealen, cdea, pb[0], temp192);
-  xlen = scale_expansion_zeroelim(xlen, temp192, pb[0], det384x);
-  ylen = scale_expansion_zeroelim(cdealen, cdea, pb[1], temp192);
-  ylen = scale_expansion_zeroelim(ylen, temp192, pb[1], det384y);
-  zlen = scale_expansion_zeroelim(cdealen, cdea, pb[2], temp192);
-  zlen = scale_expansion_zeroelim(zlen, temp192, pb[2], det384z);
-  xylen = fast_expansion_sum_zeroelim(xlen, det384x, ylen, det384y, detxy);
-  blen = fast_expansion_sum_zeroelim(xylen, detxy, zlen, det384z, bdet);
-
-  temp48alen = fast_expansion_sum_zeroelim(eablen, eab, deblen, deb, temp48a);
-  temp48blen = fast_expansion_sum_zeroelim(abdlen, abd, dealen, dea, temp48b);
-  for (i = 0; i < temp48blen; i++) {
-    temp48b[i] = -temp48b[i];
-  }
-  deablen = fast_expansion_sum_zeroelim(temp48alen, temp48a,
-                                        temp48blen, temp48b, deab);
-  xlen = scale_expansion_zeroelim(deablen, deab, pc[0], temp192);
-  xlen = scale_expansion_zeroelim(xlen, temp192, pc[0], det384x);
-  ylen = scale_expansion_zeroelim(deablen, deab, pc[1], temp192);
-  ylen = scale_expansion_zeroelim(ylen, temp192, pc[1], det384y);
-  zlen = scale_expansion_zeroelim(deablen, deab, pc[2], temp192);
-  zlen = scale_expansion_zeroelim(zlen, temp192, pc[2], det384z);
-  xylen = fast_expansion_sum_zeroelim(xlen, det384x, ylen, det384y, detxy);
-  clen = fast_expansion_sum_zeroelim(xylen, detxy, zlen, det384z, cdet);
-
-  temp48alen = fast_expansion_sum_zeroelim(abclen, abc, eaclen, eac, temp48a);
-  temp48blen = fast_expansion_sum_zeroelim(bcelen, bce, eablen, eab, temp48b);
-  for (i = 0; i < temp48blen; i++) {
-    temp48b[i] = -temp48b[i];
-  }
-  eabclen = fast_expansion_sum_zeroelim(temp48alen, temp48a,
-                                        temp48blen, temp48b, eabc);
-  xlen = scale_expansion_zeroelim(eabclen, eabc, pd[0], temp192);
-  xlen = scale_expansion_zeroelim(xlen, temp192, pd[0], det384x);
-  ylen = scale_expansion_zeroelim(eabclen, eabc, pd[1], temp192);
-  ylen = scale_expansion_zeroelim(ylen, temp192, pd[1], det384y);
-  zlen = scale_expansion_zeroelim(eabclen, eabc, pd[2], temp192);
-  zlen = scale_expansion_zeroelim(zlen, temp192, pd[2], det384z);
-  xylen = fast_expansion_sum_zeroelim(xlen, det384x, ylen, det384y, detxy);
-  dlen = fast_expansion_sum_zeroelim(xylen, detxy, zlen, det384z, ddet);
-
-  temp48alen = fast_expansion_sum_zeroelim(bcdlen, bcd, abdlen, abd, temp48a);
-  temp48blen = fast_expansion_sum_zeroelim(cdalen, cda, abclen, abc, temp48b);
-  for (i = 0; i < temp48blen; i++) {
-    temp48b[i] = -temp48b[i];
-  }
-  abcdlen = fast_expansion_sum_zeroelim(temp48alen, temp48a,
-                                        temp48blen, temp48b, abcd);
-  xlen = scale_expansion_zeroelim(abcdlen, abcd, pe[0], temp192);
-  xlen = scale_expansion_zeroelim(xlen, temp192, pe[0], det384x);
-  ylen = scale_expansion_zeroelim(abcdlen, abcd, pe[1], temp192);
-  ylen = scale_expansion_zeroelim(ylen, temp192, pe[1], det384y);
-  zlen = scale_expansion_zeroelim(abcdlen, abcd, pe[2], temp192);
-  zlen = scale_expansion_zeroelim(zlen, temp192, pe[2], det384z);
-  xylen = fast_expansion_sum_zeroelim(xlen, det384x, ylen, det384y, detxy);
-  elen = fast_expansion_sum_zeroelim(xylen, detxy, zlen, det384z, edet);
-
-  ablen = fast_expansion_sum_zeroelim(alen, adet, blen, bdet, abdet);
-  cdlen = fast_expansion_sum_zeroelim(clen, cdet, dlen, ddet, cddet);
-  cdelen = fast_expansion_sum_zeroelim(cdlen, cddet, elen, edet, cdedet);
-  deterlen = fast_expansion_sum_zeroelim(ablen, abdet, cdelen, cdedet, deter);
-
-  return deter[deterlen - 1];
-}
-
-static REAL insphereadapt(REAL *pa, REAL *pb, REAL *pc, REAL *pd, REAL *pe, 
-			  REAL permanent)
-{
-  INEXACT REAL aex, bex, cex, dex, aey, bey, cey, dey, aez, bez, cez, dez;
-  REAL det, errbound;
-
-  INEXACT REAL aexbey1, bexaey1, bexcey1, cexbey1;
-  INEXACT REAL cexdey1, dexcey1, dexaey1, aexdey1;
-  INEXACT REAL aexcey1, cexaey1, bexdey1, dexbey1;
-  REAL aexbey0, bexaey0, bexcey0, cexbey0;
-  REAL cexdey0, dexcey0, dexaey0, aexdey0;
-  REAL aexcey0, cexaey0, bexdey0, dexbey0;
-  REAL ab[4], bc[4], cd[4], da[4], ac[4], bd[4];
-  INEXACT REAL ab3, bc3, cd3, da3, ac3, bd3;
-  REAL abeps, bceps, cdeps, daeps, aceps, bdeps;
-  REAL temp8a[8], temp8b[8], temp8c[8], temp16[16], temp24[24], temp48[48];
-  int temp8alen, temp8blen, temp8clen, temp16len, temp24len, temp48len;
-  REAL xdet[96], ydet[96], zdet[96], xydet[192];
-  int xlen, ylen, zlen, xylen;
-  REAL adet[288], bdet[288], cdet[288], ddet[288];
-  int alen, blen, clen, dlen;
-  REAL abdet[576], cddet[576];
-  int ablen, cdlen;
-  REAL fin1[1152];
-  int finlength;
-
-  REAL aextail, bextail, cextail, dextail;
-  REAL aeytail, beytail, ceytail, deytail;
-  REAL aeztail, beztail, ceztail, deztail;
-
-  INEXACT REAL bvirt;
-  REAL avirt, bround, around;
-  INEXACT REAL c;
-  INEXACT REAL abig;
-  REAL ahi, alo, bhi, blo;
-  REAL err1, err2, err3;
-  INEXACT REAL _i, _j;
-  REAL _0;
-
-  aex = (REAL) (pa[0] - pe[0]);
-  bex = (REAL) (pb[0] - pe[0]);
-  cex = (REAL) (pc[0] - pe[0]);
-  dex = (REAL) (pd[0] - pe[0]);
-  aey = (REAL) (pa[1] - pe[1]);
-  bey = (REAL) (pb[1] - pe[1]);
-  cey = (REAL) (pc[1] - pe[1]);
-  dey = (REAL) (pd[1] - pe[1]);
-  aez = (REAL) (pa[2] - pe[2]);
-  bez = (REAL) (pb[2] - pe[2]);
-  cez = (REAL) (pc[2] - pe[2]);
-  dez = (REAL) (pd[2] - pe[2]);
-
-  Two_Product(aex, bey, aexbey1, aexbey0);
-  Two_Product(bex, aey, bexaey1, bexaey0);
-  Two_Two_Diff(aexbey1, aexbey0, bexaey1, bexaey0, ab3, ab[2], ab[1], ab[0]);
-  ab[3] = ab3;
-
-  Two_Product(bex, cey, bexcey1, bexcey0);
-  Two_Product(cex, bey, cexbey1, cexbey0);
-  Two_Two_Diff(bexcey1, bexcey0, cexbey1, cexbey0, bc3, bc[2], bc[1], bc[0]);
-  bc[3] = bc3;
-
-  Two_Product(cex, dey, cexdey1, cexdey0);
-  Two_Product(dex, cey, dexcey1, dexcey0);
-  Two_Two_Diff(cexdey1, cexdey0, dexcey1, dexcey0, cd3, cd[2], cd[1], cd[0]);
-  cd[3] = cd3;
-
-  Two_Product(dex, aey, dexaey1, dexaey0);
-  Two_Product(aex, dey, aexdey1, aexdey0);
-  Two_Two_Diff(dexaey1, dexaey0, aexdey1, aexdey0, da3, da[2], da[1], da[0]);
-  da[3] = da3;
-
-  Two_Product(aex, cey, aexcey1, aexcey0);
-  Two_Product(cex, aey, cexaey1, cexaey0);
-  Two_Two_Diff(aexcey1, aexcey0, cexaey1, cexaey0, ac3, ac[2], ac[1], ac[0]);
-  ac[3] = ac3;
-
-  Two_Product(bex, dey, bexdey1, bexdey0);
-  Two_Product(dex, bey, dexbey1, dexbey0);
-  Two_Two_Diff(bexdey1, bexdey0, dexbey1, dexbey0, bd3, bd[2], bd[1], bd[0]);
-  bd[3] = bd3;
-
-  temp8alen = scale_expansion_zeroelim(4, cd, bez, temp8a);
-  temp8blen = scale_expansion_zeroelim(4, bd, -cez, temp8b);
-  temp8clen = scale_expansion_zeroelim(4, bc, dez, temp8c);
-  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a,
-                                          temp8blen, temp8b, temp16);
-  temp24len = fast_expansion_sum_zeroelim(temp8clen, temp8c,
-                                          temp16len, temp16, temp24);
-  temp48len = scale_expansion_zeroelim(temp24len, temp24, aex, temp48);
-  xlen = scale_expansion_zeroelim(temp48len, temp48, -aex, xdet);
-  temp48len = scale_expansion_zeroelim(temp24len, temp24, aey, temp48);
-  ylen = scale_expansion_zeroelim(temp48len, temp48, -aey, ydet);
-  temp48len = scale_expansion_zeroelim(temp24len, temp24, aez, temp48);
-  zlen = scale_expansion_zeroelim(temp48len, temp48, -aez, zdet);
-  xylen = fast_expansion_sum_zeroelim(xlen, xdet, ylen, ydet, xydet);
-  alen = fast_expansion_sum_zeroelim(xylen, xydet, zlen, zdet, adet);
-
-  temp8alen = scale_expansion_zeroelim(4, da, cez, temp8a);
-  temp8blen = scale_expansion_zeroelim(4, ac, dez, temp8b);
-  temp8clen = scale_expansion_zeroelim(4, cd, aez, temp8c);
-  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a,
-                                          temp8blen, temp8b, temp16);
-  temp24len = fast_expansion_sum_zeroelim(temp8clen, temp8c,
-                                          temp16len, temp16, temp24);
-  temp48len = scale_expansion_zeroelim(temp24len, temp24, bex, temp48);
-  xlen = scale_expansion_zeroelim(temp48len, temp48, bex, xdet);
-  temp48len = scale_expansion_zeroelim(temp24len, temp24, bey, temp48);
-  ylen = scale_expansion_zeroelim(temp48len, temp48, bey, ydet);
-  temp48len = scale_expansion_zeroelim(temp24len, temp24, bez, temp48);
-  zlen = scale_expansion_zeroelim(temp48len, temp48, bez, zdet);
-  xylen = fast_expansion_sum_zeroelim(xlen, xdet, ylen, ydet, xydet);
-  blen = fast_expansion_sum_zeroelim(xylen, xydet, zlen, zdet, bdet);
-
-  temp8alen = scale_expansion_zeroelim(4, ab, dez, temp8a);
-  temp8blen = scale_expansion_zeroelim(4, bd, aez, temp8b);
-  temp8clen = scale_expansion_zeroelim(4, da, bez, temp8c);
-  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a,
-                                          temp8blen, temp8b, temp16);
-  temp24len = fast_expansion_sum_zeroelim(temp8clen, temp8c,
-                                          temp16len, temp16, temp24);
-  temp48len = scale_expansion_zeroelim(temp24len, temp24, cex, temp48);
-  xlen = scale_expansion_zeroelim(temp48len, temp48, -cex, xdet);
-  temp48len = scale_expansion_zeroelim(temp24len, temp24, cey, temp48);
-  ylen = scale_expansion_zeroelim(temp48len, temp48, -cey, ydet);
-  temp48len = scale_expansion_zeroelim(temp24len, temp24, cez, temp48);
-  zlen = scale_expansion_zeroelim(temp48len, temp48, -cez, zdet);
-  xylen = fast_expansion_sum_zeroelim(xlen, xdet, ylen, ydet, xydet);
-  clen = fast_expansion_sum_zeroelim(xylen, xydet, zlen, zdet, cdet);
-
-  temp8alen = scale_expansion_zeroelim(4, bc, aez, temp8a);
-  temp8blen = scale_expansion_zeroelim(4, ac, -bez, temp8b);
-  temp8clen = scale_expansion_zeroelim(4, ab, cez, temp8c);
-  temp16len = fast_expansion_sum_zeroelim(temp8alen, temp8a,
-                                          temp8blen, temp8b, temp16);
-  temp24len = fast_expansion_sum_zeroelim(temp8clen, temp8c,
-                                          temp16len, temp16, temp24);
-  temp48len = scale_expansion_zeroelim(temp24len, temp24, dex, temp48);
-  xlen = scale_expansion_zeroelim(temp48len, temp48, dex, xdet);
-  temp48len = scale_expansion_zeroelim(temp24len, temp24, dey, temp48);
-  ylen = scale_expansion_zeroelim(temp48len, temp48, dey, ydet);
-  temp48len = scale_expansion_zeroelim(temp24len, temp24, dez, temp48);
-  zlen = scale_expansion_zeroelim(temp48len, temp48, dez, zdet);
-  xylen = fast_expansion_sum_zeroelim(xlen, xdet, ylen, ydet, xydet);
-  dlen = fast_expansion_sum_zeroelim(xylen, xydet, zlen, zdet, ddet);
-
-  ablen = fast_expansion_sum_zeroelim(alen, adet, blen, bdet, abdet);
-  cdlen = fast_expansion_sum_zeroelim(clen, cdet, dlen, ddet, cddet);
-  finlength = fast_expansion_sum_zeroelim(ablen, abdet, cdlen, cddet, fin1);
-
-  det = estimate(finlength, fin1);
-  errbound = isperrboundB * permanent;
-  if ((det >= errbound) || (-det >= errbound)) {
-    return det;
-  }
-
-  Two_Diff_Tail(pa[0], pe[0], aex, aextail);
-  Two_Diff_Tail(pa[1], pe[1], aey, aeytail);
-  Two_Diff_Tail(pa[2], pe[2], aez, aeztail);
-  Two_Diff_Tail(pb[0], pe[0], bex, bextail);
-  Two_Diff_Tail(pb[1], pe[1], bey, beytail);
-  Two_Diff_Tail(pb[2], pe[2], bez, beztail);
-  Two_Diff_Tail(pc[0], pe[0], cex, cextail);
-  Two_Diff_Tail(pc[1], pe[1], cey, ceytail);
-  Two_Diff_Tail(pc[2], pe[2], cez, ceztail);
-  Two_Diff_Tail(pd[0], pe[0], dex, dextail);
-  Two_Diff_Tail(pd[1], pe[1], dey, deytail);
-  Two_Diff_Tail(pd[2], pe[2], dez, deztail);
-  if ((aextail == 0.0) && (aeytail == 0.0) && (aeztail == 0.0)
-      && (bextail == 0.0) && (beytail == 0.0) && (beztail == 0.0)
-      && (cextail == 0.0) && (ceytail == 0.0) && (ceztail == 0.0)
-      && (dextail == 0.0) && (deytail == 0.0) && (deztail == 0.0)) {
-    return det;
-  }
-
-  errbound = isperrboundC * permanent + resulterrbound * Absolute(det);
-  abeps = (aex * beytail + bey * aextail)
-        - (aey * bextail + bex * aeytail);
-  bceps = (bex * ceytail + cey * bextail)
-        - (bey * cextail + cex * beytail);
-  cdeps = (cex * deytail + dey * cextail)
-        - (cey * dextail + dex * ceytail);
-  daeps = (dex * aeytail + aey * dextail)
-        - (dey * aextail + aex * deytail);
-  aceps = (aex * ceytail + cey * aextail)
-        - (aey * cextail + cex * aeytail);
-  bdeps = (bex * deytail + dey * bextail)
-        - (bey * dextail + dex * beytail);
-  det += (((bex * bex + bey * bey + bez * bez)
-           * ((cez * daeps + dez * aceps + aez * cdeps)
-              + (ceztail * da3 + deztail * ac3 + aeztail * cd3))
-           + (dex * dex + dey * dey + dez * dez)
-           * ((aez * bceps - bez * aceps + cez * abeps)
-              + (aeztail * bc3 - beztail * ac3 + ceztail * ab3)))
-          - ((aex * aex + aey * aey + aez * aez)
-           * ((bez * cdeps - cez * bdeps + dez * bceps)
-              + (beztail * cd3 - ceztail * bd3 + deztail * bc3))
-           + (cex * cex + cey * cey + cez * cez)
-           * ((dez * abeps + aez * bdeps + bez * daeps)
-              + (deztail * ab3 + aeztail * bd3 + beztail * da3))))
-       + 2.0 * (((bex * bextail + bey * beytail + bez * beztail)
-                 * (cez * da3 + dez * ac3 + aez * cd3)
-                 + (dex * dextail + dey * deytail + dez * deztail)
-                 * (aez * bc3 - bez * ac3 + cez * ab3))
-                - ((aex * aextail + aey * aeytail + aez * aeztail)
-                 * (bez * cd3 - cez * bd3 + dez * bc3)
-                 + (cex * cextail + cey * ceytail + cez * ceztail)
-                 * (dez * ab3 + aez * bd3 + bez * da3)));
-  if ((det >= errbound) || (-det >= errbound)) {
-    return det;
-  }
-
-  return insphereexact(pa, pb, pc, pd, pe);
-}
-
-REAL insphere(pa, pb, pc, pd, pe)
-REAL *pa;
-REAL *pb;
-REAL *pc;
-REAL *pd;
-REAL *pe;
-{
-  REAL aex, bex, cex, dex;
-  REAL aey, bey, cey, dey;
-  REAL aez, bez, cez, dez;
-  REAL aexbey, bexaey, bexcey, cexbey, cexdey, dexcey, dexaey, aexdey;
-  REAL aexcey, cexaey, bexdey, dexbey;
-  REAL alift, blift, clift, dlift;
-  REAL ab, bc, cd, da, ac, bd;
-  REAL abc, bcd, cda, dab;
-  REAL aezplus, bezplus, cezplus, dezplus;
-  REAL aexbeyplus, bexaeyplus, bexceyplus, cexbeyplus;
-  REAL cexdeyplus, dexceyplus, dexaeyplus, aexdeyplus;
-  REAL aexceyplus, cexaeyplus, bexdeyplus, dexbeyplus;
-  REAL det;
-  REAL permanent, errbound;
-  REAL ins;
-
-  FPU_ROUND_DOUBLE;
-
-  aex = pa[0] - pe[0];
-  bex = pb[0] - pe[0];
-  cex = pc[0] - pe[0];
-  dex = pd[0] - pe[0];
-  aey = pa[1] - pe[1];
-  bey = pb[1] - pe[1];
-  cey = pc[1] - pe[1];
-  dey = pd[1] - pe[1];
-  aez = pa[2] - pe[2];
-  bez = pb[2] - pe[2];
-  cez = pc[2] - pe[2];
-  dez = pd[2] - pe[2];
-
-  aexbey = aex * bey;
-  bexaey = bex * aey;
-  ab = aexbey - bexaey;
-  bexcey = bex * cey;
-  cexbey = cex * bey;
-  bc = bexcey - cexbey;
-  cexdey = cex * dey;
-  dexcey = dex * cey;
-  cd = cexdey - dexcey;
-  dexaey = dex * aey;
-  aexdey = aex * dey;
-  da = dexaey - aexdey;
-
-  aexcey = aex * cey;
-  cexaey = cex * aey;
-  ac = aexcey - cexaey;
-  bexdey = bex * dey;
-  dexbey = dex * bey;
-  bd = bexdey - dexbey;
-
-  abc = aez * bc - bez * ac + cez * ab;
-  bcd = bez * cd - cez * bd + dez * bc;
-  cda = cez * da + dez * ac + aez * cd;
-  dab = dez * ab + aez * bd + bez * da;
-
-  alift = aex * aex + aey * aey + aez * aez;
-  blift = bex * bex + bey * bey + bez * bez;
-  clift = cex * cex + cey * cey + cez * cez;
-  dlift = dex * dex + dey * dey + dez * dez;
-
-  det = (dlift * abc - clift * dab) + (blift * cda - alift * bcd);
-
-  aezplus = Absolute(aez);
-  bezplus = Absolute(bez);
-  cezplus = Absolute(cez);
-  dezplus = Absolute(dez);
-  aexbeyplus = Absolute(aexbey);
-  bexaeyplus = Absolute(bexaey);
-  bexceyplus = Absolute(bexcey);
-  cexbeyplus = Absolute(cexbey);
-  cexdeyplus = Absolute(cexdey);
-  dexceyplus = Absolute(dexcey);
-  dexaeyplus = Absolute(dexaey);
-  aexdeyplus = Absolute(aexdey);
-  aexceyplus = Absolute(aexcey);
-  cexaeyplus = Absolute(cexaey);
-  bexdeyplus = Absolute(bexdey);
-  dexbeyplus = Absolute(dexbey);
-  permanent = ((cexdeyplus + dexceyplus) * bezplus
-               + (dexbeyplus + bexdeyplus) * cezplus
-               + (bexceyplus + cexbeyplus) * dezplus)
-            * alift
-            + ((dexaeyplus + aexdeyplus) * cezplus
-               + (aexceyplus + cexaeyplus) * dezplus
-               + (cexdeyplus + dexceyplus) * aezplus)
-            * blift
-            + ((aexbeyplus + bexaeyplus) * dezplus
-               + (bexdeyplus + dexbeyplus) * aezplus
-               + (dexaeyplus + aexdeyplus) * bezplus)
-            * clift
-            + ((bexceyplus + cexbeyplus) * aezplus
-               + (cexaeyplus + aexceyplus) * bezplus
-               + (aexbeyplus + bexaeyplus) * cezplus)
-            * dlift;
-  errbound = isperrboundA * permanent;
-  if ((det > errbound) || (-det > errbound)) {
-    FPU_RESTORE;
-    return det;
-  }
-
-  ins = insphereadapt(pa, pb, pc, pd, pe, permanent);
-  FPU_RESTORE;
-  return ins;
-}
diff --git a/src/gts/predicates.h b/src/gts/predicates.h
deleted file mode 100644
index 8b026ed..0000000
--- a/src/gts/predicates.h
+++ /dev/null
@@ -1,41 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-/* Header file for robust predicates by Jonathan Richard Shewchuk */
-
-#ifndef __PREDICATES_H__
-#define __PREDICATES_H__
-
-double orient2d            (double * pa,
-			    double * pb,
-			    double * pc);
-double orient3d            (double * pa,
-			    double * pb,
-			    double * pc,
-			    double * pd);
-double incircle            (double * pa,
-			    double * pb,
-			    double * pc,
-			    double * pd);
-double insphere            (double * pa,
-			    double * pb,
-			    double * pc,
-			    double * pd,
-			    double * pe);
-
-#endif /* __PREDICATES_H__ */
diff --git a/src/gts/psurface.c b/src/gts/psurface.c
deleted file mode 100644
index 6db3ae2..0000000
--- a/src/gts/psurface.c
+++ /dev/null
@@ -1,471 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <stdlib.h>
-#include <math.h>
-#include "gts.h"
-
-#define HEAP_INSERT_OBJECT(h, e) (GTS_OBJECT (e)->reserved =\
-                                   gts_eheap_insert (h, e))
-#define HEAP_REMOVE_OBJECT(h, e) (gts_eheap_remove (h, GTS_OBJECT (e)->reserved),\
-				  GTS_OBJECT (e)->reserved = NULL)
-
-static void psurface_destroy (GtsObject * object)
-{
-  GtsPSurface * ps = GTS_PSURFACE (object);
-  guint i;
-
-  if (!GTS_PSURFACE_IS_CLOSED (ps))
-    gts_psurface_close (ps);
-
-  for (i = 0; i < ps->split->len; i++)
-    if (g_ptr_array_index (ps->split, i))
-      gts_object_destroy (GTS_OBJECT (g_ptr_array_index (ps->split, i)));
-  g_ptr_array_free (ps->split, TRUE);
-
-  (* GTS_OBJECT_CLASS (gts_psurface_class ())->parent_class->destroy) (object);
-}
-
-static void psurface_class_init (GtsObjectClass * klass)
-{
-  klass->destroy = psurface_destroy;
-}
-
-static void psurface_init (GtsPSurface * psurface)
-{
-  psurface->s = NULL;
-  psurface->split = g_ptr_array_new ();
-  psurface->split_class = gts_split_class ();
-  psurface->pos = psurface->min = 0;
-  psurface->vertices = psurface->faces = NULL;
-}
-
-/**
- * gts_psurface_class:
- * 
- * Returns: the #GtsPSurfaceClass.
- */
-GtsPSurfaceClass * gts_psurface_class (void)
-{
-  static GtsPSurfaceClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo psurface_info = {
-      "GtsPSurface",
-      sizeof (GtsPSurface),
-      sizeof (GtsPSurfaceClass),
-      (GtsObjectClassInitFunc) psurface_class_init,
-      (GtsObjectInitFunc) psurface_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (gts_object_class (), 
-				  &psurface_info);
-  }
-
-  return klass;
-}
-
-static GtsVertex * edge_collapse (GtsPSurface * ps,
-				  GtsEdge * e,
-				  GtsEHeap * heap,
-				  GtsCoarsenFunc coarsen_func,
-				  gpointer coarsen_data,
-				  gdouble maxcosine2)
-{
-  GtsVertex  * v1 = GTS_SEGMENT (e)->v1, * v2 = GTS_SEGMENT (e)->v2, * mid;
-  GtsSplit * vs;
-  GtsObject * o1, * o2;
-
-  /* if the edge is degenerate (i.e. v1 == v2), destroy and return */
-  if (v1 == v2) {
-    gts_object_destroy (GTS_OBJECT (e));
-    return NULL;
-  }
-
-  if (!gts_edge_collapse_is_valid (e) ||
-      /* check that a non-manifold edge is not a contact edge */
-      (g_slist_length (e->triangles) > 2 && gts_edge_is_contact (e) > 1)) {
-    GTS_OBJECT (e)->reserved = 
-      gts_eheap_insert_with_key (heap, e, G_MAXDOUBLE);
-    return NULL;
-  }
-
-  mid = (*coarsen_func) (e, ps->s->vertex_class, coarsen_data);
-
-  if (gts_edge_collapse_creates_fold (e, mid, maxcosine2)) {
-    GTS_OBJECT (e)->reserved = 
-      gts_eheap_insert_with_key (heap, e, G_MAXDOUBLE);
-    gts_object_destroy (GTS_OBJECT (mid));
-    return NULL;
-  }
-
-  if (GTS_OBJECT (v1)->reserved)
-    o1 = GTS_OBJECT (v1)->reserved;
-  else
-    o1 = GTS_OBJECT (v1);
-  if (GTS_OBJECT (v2)->reserved)
-    o2 = GTS_OBJECT (v2)->reserved;
-  else
-    o2 = GTS_OBJECT (v2);
-  vs = gts_split_new (ps->split_class, mid, o1, o2);
-  gts_split_collapse (vs, ps->s->edge_class, heap);
-  GTS_OBJECT (vs->v)->reserved = vs;
-  g_ptr_array_add (ps->split, vs);
-
-  return mid;
-}
-
-static void update_2nd_closest_neighbors (GtsVertex * v, GtsEHeap * heap)
-{
-  GSList * i = v->segments;
-  GSList * list = NULL;
-  
-  while (i) {
-    GtsSegment * s = i->data;
-    if (GTS_IS_EDGE (s)) {
-      GtsVertex * v1 = s->v1 == v ? s->v2 : s->v1;
-      GSList * j = v1->segments;
-      while (j) {
-	GtsSegment * s1 = j->data;
-	if (GTS_IS_EDGE (s1) && !g_slist_find (list, s1))
-	  list = g_slist_prepend (list, s1);
-	j = j->next;
-      }
-    }
-    i = i->next;
-  }
-
-  i = list;
-  while (i) {
-    GtsEdge * e = i->data;
-    if (GTS_OBJECT (e)->reserved)
-      HEAP_REMOVE_OBJECT (heap, e);
-    HEAP_INSERT_OBJECT (heap, e);
-    i = i->next;
-  }
-
-  g_slist_free (list);
-}
-
-static gdouble edge_length2 (GtsEdge * e)
-{
-  return gts_point_distance2 (GTS_POINT (GTS_SEGMENT (e)->v1), 
-			      GTS_POINT (GTS_SEGMENT (e)->v2));
-}
-
-static void create_heap_coarsen (GtsEdge * e, GtsEHeap * heap)
-{
-  HEAP_INSERT_OBJECT (heap, e);
-}
-
-/* #define DEBUG_FOLD */
-/* #define DEBUG_CONTACT_VERTEX */
-
-#ifdef DEBUG_FOLD
-static void check_fold (GtsTriangle * t, gdouble * maxcosine2)
-{
-  GtsEdge * e1 = t->e1, * e2 = t->e2, * e3 = t->e3;
-
-  
-  if (gts_triangles_are_folded (e1->triangles, 
-				GTS_SEGMENT (e1)->v1,
-				GTS_SEGMENT (e1)->v2,
-				*maxcosine2) ||
-      gts_triangles_are_folded (e2->triangles, 
-				GTS_SEGMENT (e2)->v1,
-				GTS_SEGMENT (e2)->v2,
-				*maxcosine2) ||
-      gts_triangles_are_folded (e3->triangles, 
-				GTS_SEGMENT (e3)->v1,
-				GTS_SEGMENT (e3)->v2,
-				*maxcosine2)) {
-    fprintf (stderr, "triangle %p:(%p,%p,%p) is folded\n", t, e1, e2, e3);
-    g_assert_not_reached ();
-  }
-}
-#endif
-
-/**
- * gts_psurface_new:
- * @klass: a #GtsPSurfaceClass.
- * @surface: a #GtsSurface.
- * @split_class: a #GtsSplitClass to use for the new progressive surface.
- * @cost_func: cost function for the edge collapse algorithm.
- * @cost_data: data to pass to @cost_func.
- * @coarsen_func: the function returning the vertex replacement for the edge 
- * collapse.
- * @coarsen_data: data to pass to @coarsen_func.
- * @stop_func: the function to call to decide whether to stop the coarsening
- * process.
- * @stop_data: data to pass to @stop_func.
- * @minangle: the minimum angle allowable between two neighboring triangles. 
- * This is used to avoid introducing folds in the mesh during simplification.
- *
- * This function works in exactly the same way as the
- * gts_surface_coarsen() function, except that the history of edge
- * collapse is saved in an array of #GtsSplit objects. This allows for
- * dynamic continuous multiresolution control of the input @surface.
- *
- * Returns: a new progressive surface.
- */
-GtsPSurface * gts_psurface_new (GtsPSurfaceClass * klass,
-				GtsSurface * surface,
-				GtsSplitClass * split_class,
-				GtsKeyFunc cost_func,
-				gpointer cost_data,
-				GtsCoarsenFunc coarsen_func,
-				gpointer coarsen_data,
-				GtsStopFunc stop_func,
-				gpointer stop_data,
-				gdouble minangle)
-{
-  GtsPSurface * psurface;
-  GtsEHeap * heap;
-  GtsEdge * e;
-  gdouble top_cost, maxcosine2;
-  guint i;
-
-  g_return_val_if_fail (klass != NULL, NULL);
-  g_return_val_if_fail (surface != NULL, NULL);
-  g_return_val_if_fail (split_class != NULL, NULL);
-  g_return_val_if_fail (stop_func != NULL, NULL);
-
-  psurface = GTS_PSURFACE (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  psurface->s = surface;
-  psurface->split_class = split_class;
-
-  if (cost_func == NULL)
-    cost_func = (GtsKeyFunc) edge_length2;
-  if (coarsen_func == NULL)
-    coarsen_func = (GtsCoarsenFunc) gts_segment_midvertex;
-
-  heap = gts_eheap_new (cost_func, cost_data);
-  maxcosine2 = cos (minangle); maxcosine2 *= maxcosine2;
-
-  gts_eheap_freeze (heap);
-  gts_surface_foreach_edge (surface, (GtsFunc) create_heap_coarsen, heap);
-  gts_eheap_thaw (heap);
-  /* we want to control edge destruction manually */
-  gts_allow_floating_edges = TRUE;
-  while ((e = gts_eheap_remove_top (heap, &top_cost)) &&
-	 (top_cost < G_MAXDOUBLE) &&
-	 !(*stop_func) (top_cost, gts_eheap_size (heap) - 
-			gts_edge_face_number (e, surface), stop_data)) {
-    GtsVertex * v = edge_collapse (psurface, e, heap, 
-				   coarsen_func, coarsen_data, maxcosine2);
-    if (v != NULL) {
-      update_2nd_closest_neighbors (v, heap);
-#ifdef DEBUG_FOLD
-      {
-	GSList * triangles = gts_vertex_triangles (v, NULL), * i;
-	fprintf (stderr, "\n---- Check for folds ----\n%p: ", v);
-	i = triangles;
-	while (i) {
-	  GtsTriangle * t = i->data;
-	  fprintf (stderr, "%p:(%p,%p,%p) ", t, t->e1, t->e2, t->e3);
-	  i = i->next;
-	}
-	fprintf (stderr, "\n");
-	g_slist_free (triangles);
-	gts_surface_foreach_face (surface, (GtsFunc) check_fold, &maxcosine2);
-      }
-#endif
-#ifdef DEBUG_CONTACT_VERTEX
-      if (gts_vertex_is_contact (v, FALSE) != 1) {
-	FILE * fptr = fopen ("after", "wt");
-	GSList * triangles = gts_vertex_triangles (v, NULL), * i;
-
-	fprintf (stderr, "collapse of %p created a contact vertex\n", e);
-		 
-	fprintf (fptr, 
-		 "(geometry \"sphere\" { = SPHERE 0.1 0. 0. 0. })\n"
-		 "(normalization \"sphere\" none)\n");
-	i = triangles;
-	while (i) {
-	  gts_write_triangle (i->data, GTS_POINT (v), fptr);
-	  i = i->next;
-	}
-	g_assert_not_reached ();
-      }
-#endif
-    }
-  }
-  gts_allow_floating_edges = FALSE;
-
-  /* set reserved field of remaining edges back to NULL */
-  if (e) GTS_OBJECT (e)->reserved = NULL;
-  gts_eheap_foreach (heap, (GFunc) gts_object_reset_reserved, NULL);
-
-  gts_eheap_destroy (heap);
-
-  psurface->pos = psurface->split->len;
-  psurface->min = gts_surface_vertex_number (psurface->s);
-
-  /* set reserved field of vertices (used to build the hierarchy) 
-     back to NULL */
-  for (i = 0; i < psurface->split->len; i++) {
-    GtsSplit * vs = g_ptr_array_index (psurface->split, i);
-    gts_object_reset_reserved (GTS_OBJECT (vs->v));
-  }
-
-  return psurface;
-}
-
-/**
- * gts_psurface_add_vertex:
- * @ps: a #GtsPSurface.
- *
- * Adds a vertex to the progressive surface @ps by expanding the next
- * available #GtsSplit.
- *
- * Returns: the expanded #GtsSplit or %NULL if all the #GtsSplit have already
- * been expanded.
- */
-GtsSplit * gts_psurface_add_vertex (GtsPSurface * ps) 
-{ 
-  GtsSplit * vs;
-
-  g_return_val_if_fail (ps != NULL, NULL);
-  g_return_val_if_fail (GTS_PSURFACE_IS_CLOSED (ps), NULL);
-
-  if (ps->pos == 0)
-    return NULL;
-
-  vs = g_ptr_array_index (ps->split, --ps->pos);
-  gts_split_expand (vs, ps->s, ps->s->edge_class);
-
-  return vs;
-}
-
-/**
- * gts_psurface_remove_vertex:
- * @ps: a #GtsPSurface.
- *
- * Removes one vertex from the progressive surface @ps by collapsing the first
- * available #GtsSplit.
- *
- * Returns: the collapsed #GtsSplit or %NULL if all the #GtsSplit have already
- * been collapsed.
- */
-GtsSplit * gts_psurface_remove_vertex (GtsPSurface * ps)
-{
-  GtsSplit * vs;
-
-  g_return_val_if_fail (ps != NULL, NULL);
-  g_return_val_if_fail (GTS_PSURFACE_IS_CLOSED (ps), NULL);
-
-  if (ps->pos == ps->split->len)
-    return NULL;
-
-  vs = g_ptr_array_index (ps->split, ps->pos++);
-  gts_split_collapse (vs, ps->s->edge_class, NULL);
-
-  return vs;
-}
-
-/**
- * gts_psurface_max_vertex_number:
- * @ps: a #GtsPSurface.
- *
- * Returns: the maximum number of vertices of @ps i.e. the number of vertices
- * if all the #GtsSplit were expanded.
- */
-guint gts_psurface_max_vertex_number (GtsPSurface * ps)
-{
-  g_return_val_if_fail (ps != NULL, 0);
-
-  return ps->min + ps->split->len;
-}
-
-/**
- * gts_psurface_min_vertex_number:
- * @ps: a #GtsPSurface.
- *
- * Returns: the minimum number of vertices of @ps i.e. the number of vertices
- * if all the #GtsSplit were collapsed.
- */
-guint gts_psurface_min_vertex_number (GtsPSurface * ps)
-{
-  g_return_val_if_fail (ps != NULL, 0);
-
-  return ps->min;
-}
-
-/**
- * gts_psurface_set_vertex_number:
- * @ps: a #GtsPSurface.
- * @n: a number of vertices.
- *
- * Performs the required number of collapses or expansions to set the number
- * of vertices of @ps to @n.
- */
-void gts_psurface_set_vertex_number (GtsPSurface * ps, guint n)
-{
-  g_return_if_fail (ps != NULL);
-  g_return_if_fail (GTS_PSURFACE_IS_CLOSED (ps));
-
-  n = ps->min + ps->split->len - n;
-  while (ps->pos > n && gts_psurface_add_vertex (ps))
-    ;
-  while (ps->pos < n && gts_psurface_remove_vertex (ps))
-    ;
-}
-
-/**
- * gts_psurface_get_vertex_number:
- * @ps: a #GtsPSurface.
- *
- * Returns: the current number of vertices of @ps.
- */
-guint gts_psurface_get_vertex_number (GtsPSurface * ps)
-{
-  g_return_val_if_fail (ps != NULL, 0);
-  
-  if (!GTS_PSURFACE_IS_CLOSED (ps))
-    return ps->min + ps->pos;
-  else
-    return ps->min + ps->split->len - ps->pos;
-}
-
-/**
- * gts_psurface_foreach_vertex:
- * @ps: a #GtsPSurface.
- * @func: a function to call for each vertex of @ps.
- * @data: data to be passed to @func.
- *
- * Calls @func for each (potential) vertex of @ps, whether actually used
- * or not. The vertices are called in the order they were created during the
- * edge collapse operation.
- */
-void gts_psurface_foreach_vertex (GtsPSurface * ps, 
-				  GtsFunc func, 
-				  gpointer data)
-{
-  guint i;
-
-  g_return_if_fail (ps != NULL);
-  g_return_if_fail (func != NULL);
-  g_return_if_fail (GTS_PSURFACE_IS_CLOSED (ps));
-  
-  for (i = 0; i < ps->split->len; i++) {
-    GtsSplit * vs = g_ptr_array_index (ps->split, i);
-    (*func) (vs->v, data);
-  }
-}
diff --git a/src/gts/refine.c b/src/gts/refine.c
deleted file mode 100644
index 293eb11..0000000
--- a/src/gts/refine.c
+++ /dev/null
@@ -1,418 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <math.h>
-#include "gts.h"
-
-/**
- * gts_vertex_encroaches_edge:
- * @v: a #GtsVertex.
- * @e: a #GtsEdge.
- *
- * Returns: %TRUE if @v is strictly contained in the diametral circle of @e,
- * %FALSE otherwise.
- */
-gboolean gts_vertex_encroaches_edge (GtsVertex * v, GtsEdge * e)
-{
-  GtsPoint * p, * p1, * p2;
-
-  g_return_val_if_fail (v != NULL, FALSE);
-  g_return_val_if_fail (e != NULL, FALSE);
-
-  p = GTS_POINT (v);
-  p1 = GTS_POINT (GTS_SEGMENT (e)->v1);
-  p2 = GTS_POINT (GTS_SEGMENT (e)->v2);
-
-  if ((p1->x - p->x)*(p2->x - p->x) + (p1->y - p->y)*(p2->y - p->y) < 0.0)
-    return TRUE;
-  return FALSE;
-}
-
-/**
- * gts_edge_is_encroached:
- * @e: a #GtsEdge.
- * @s: a #GtsSurface describing a (constrained) Delaunay triangulation.
- * @encroaches: a #GtsEncroachFunc.
- * @data: user data to be passed to @encroaches.
- *
- * Returns: a #GtsVertex belonging to @s and encroaching upon @e
- * (as defined by @encroaches) or %NULL if there is none.  
- */
-GtsVertex * gts_edge_is_encroached (GtsEdge * e,
-				    GtsSurface * s,
-				    GtsEncroachFunc encroaches,
-				    gpointer data)
-{
-  GSList * i;
-
-  g_return_val_if_fail (e != NULL, NULL);
-  g_return_val_if_fail (s != NULL, NULL);
-  g_return_val_if_fail (encroaches != NULL, NULL);
-
-  i = e->triangles;
-  while (i) {
-    GtsFace * f = i->data;
-    if (GTS_IS_FACE (f) && gts_face_has_parent_surface (f, s)) {
-      GtsVertex * v = gts_triangle_vertex_opposite (GTS_TRIANGLE (f), e);
-      if ((* encroaches) (v, e, s, data))
-	return v;
-    }
-    i = i->next;
-  }
-
-  return NULL;
-}
-
-#define ALREADY_ENCROACHED(c) (GTS_OBJECT (c)->reserved)
-
-static void vertex_encroaches (GtsVertex * v,
-			       GtsSurface * surface,
-			       GtsFifo * encroached,
-			       GtsEncroachFunc encroaches,
-			       gpointer data)
-{
-  GSList * triangles, * i;
-
-  g_return_if_fail (v != NULL);
-  g_return_if_fail (surface != NULL);
-  g_return_if_fail (encroached != NULL);
-  g_return_if_fail (encroaches != NULL);
-
-  i = triangles = gts_vertex_triangles (v, NULL);
-  while (i) {
-    GtsFace * f = i->data;
-    if (GTS_IS_FACE (f) && gts_face_has_parent_surface (f, surface)) {
-      GtsEdge * e = gts_triangle_edge_opposite (i->data, v);
-      if (!ALREADY_ENCROACHED (e) && 
-	  GTS_IS_CONSTRAINT (e) &&
-	  (* encroaches) (v, e, surface, data)) {
-	gts_fifo_push (encroached, e);
-	ALREADY_ENCROACHED (e) = encroached;
-      }
-    }
-    i = i->next;
-  }
-  g_slist_free (triangles);
-}
-
-static void make_encroached_fifo (GtsEdge * e, gpointer * datas)
-{
-  GtsFifo * fifo = datas[0];
-  GtsSurface * s = datas[1];
-  GtsEncroachFunc encroaches = (GtsEncroachFunc) datas[2];
-  gpointer data = datas[3];
-
-  if (GTS_IS_CONSTRAINT (e) && 
-      gts_edge_is_encroached (e, s, encroaches, data)) {
-    gts_fifo_push (fifo, e);
-    ALREADY_ENCROACHED (e) = fifo;
-  }
-}
-
-#define SQUARE_ROOT_TWO 1.41421356237309504880168872420969807856967187
-#define DISTANCE_2D(v1, v2) (sqrt ((GTS_POINT (v2)->x - GTS_POINT (v1)->x)*\
-                                   (GTS_POINT (v2)->x - GTS_POINT (v1)->x) +\
-                                   (GTS_POINT (v2)->y - GTS_POINT (v1)->y)*\
-                                   (GTS_POINT (v2)->y - GTS_POINT (v1)->y)))
-
-/* finds where to split the given edge to avoid infinite cycles. (see
-   Shewchuk's thesis for details */
-static GtsVertex * split_edge (GtsEdge * e,
-			       GtsSurface * surface)
-{
-  GSList * i = e->triangles;
-  GtsEdge * c = NULL;
-
-  /* look for constraints touching e */
-  while (i && !c) {
-    GtsTriangle * t = i->data;
-    if (GTS_IS_FACE (t) && 
-	gts_face_has_parent_surface (GTS_FACE (t), surface)) {
-      GtsEdge * e1, * e2;
-      if (t->e1 == e) { e1 = t->e2; e2 = t->e3; }
-      else if (t->e2 == e) { e1 = t->e1; e2 = t->e3; }
-      else { e1 = t->e1; e2 = t->e2; }
-      if (GTS_IS_CONSTRAINT (e1) && !GTS_IS_CONSTRAINT (e2))
-	c = e1;
-      else if (GTS_IS_CONSTRAINT (e2) && !GTS_IS_CONSTRAINT (e1))
-	c = e2;
-    }
-    i = i->next;
-  }
-  if (c) {
-    /* use power of two concentric shells */
-    GtsVertex * v1 = GTS_SEGMENT (e)->v1;
-    GtsVertex * v2 = GTS_SEGMENT (e)->v2;
-    gdouble l = DISTANCE_2D (v1, v2);
-    gdouble nearestpower = 1., split;
-
-    while (l > SQUARE_ROOT_TWO*nearestpower)
-      nearestpower *= 2.;
-    while (l < SQUARE_ROOT_TWO*nearestpower/2.)
-      nearestpower /= 2.;
-    split = nearestpower/l/2.;
-
-    if (GTS_SEGMENT (c)->v1 == v2 || GTS_SEGMENT (c)->v2 == v2)
-      split = 1. - split;
-    return gts_vertex_new (surface->vertex_class,
-			   (1. - split)*GTS_POINT (v1)->x +
-			   split*GTS_POINT (v2)->x,
-			   (1. - split)*GTS_POINT (v1)->y +
-			   split*GTS_POINT (v2)->y,
-			   (1. - split)*GTS_POINT (v1)->z +
-			   split*GTS_POINT (v2)->z);
-  }
-  else
-    return gts_segment_midvertex (GTS_SEGMENT (e), surface->vertex_class);
-}
-
-static gint split_encroached (GtsSurface * surface, 
-			      GtsFifo * encroached,
-			      gint steiner_max,
-			      GtsEncroachFunc encroaches,
-			      gpointer data)
-{
-  GtsSegment * s;
-
-  while (steiner_max-- != 0 && (s = gts_fifo_pop (encroached))) {
-    GtsVertex * v = split_edge (GTS_EDGE (s), surface);
-    GtsFace * boundary = gts_edge_is_boundary (GTS_EDGE (s), surface);
-    GtsFace * f = boundary;
-#if 1
-    GtsEdge * e1 = GTS_EDGE (gts_object_clone (GTS_OBJECT (s)));
-    GtsEdge * e2 = GTS_EDGE (gts_object_clone (GTS_OBJECT (s)));
-
-    GTS_SEGMENT (e1)->v1 = s->v1;
-    s->v1->segments = g_slist_prepend (s->v1->segments, e1);
-    GTS_SEGMENT (e1)->v2 = v;
-    v->segments = g_slist_prepend (v->segments, e1);
-
-    GTS_SEGMENT (e2)->v1 = v;
-    v->segments = g_slist_prepend (v->segments, e2);
-    GTS_SEGMENT (e2)->v2 = s->v2;
-    s->v2->segments = g_slist_prepend (s->v2->segments, e2);
-#else
-    GtsEdge * e1 = gts_edge_new (GTS_EDGE_CLASS (GTS_OBJECT (s)->klass),
-				 s->v1, v);
-    GtsEdge * e2 = gts_edge_new (GTS_EDGE_CLASS (GTS_OBJECT (s)->klass),
-				 v, s->v2);
-#endif
-
-    GTS_OBJECT (s)->klass = GTS_OBJECT_CLASS (surface->edge_class);
-
-    if (f == NULL)
-      g_assert ((f = gts_edge_has_parent_surface (GTS_EDGE (s), surface)));
-    g_assert (gts_delaunay_add_vertex_to_face (surface, v, f) == NULL);
-
-    if (boundary)
-      gts_object_destroy (GTS_OBJECT (s));
-
-    vertex_encroaches (v, surface, encroached, encroaches, data);
-
-    if (gts_edge_is_encroached (e1, surface, encroaches, data)) {
-      gts_fifo_push (encroached, e1);
-      ALREADY_ENCROACHED (e1) = encroached;
-    }
-    if (gts_edge_is_encroached (e2, surface, encroaches, data)) {
-      gts_fifo_push (encroached, e2);
-      ALREADY_ENCROACHED (e2) = encroached;
-    }
-  }
-
-  return steiner_max;
-}
-
-/**
- * gts_delaunay_conform:
- * @surface: a #GtsSurface describing a constrained Delaunay triangulation.
- * @steiner_max: maximum number of Steiner points.
- * @encroaches: a #GtsEncroachFunc.
- * @data: user-data to pass to @encroaches.
- *
- * Recursively split constraints of @surface which are encroached by
- * vertices of @surface (see Shewchuk 96 for details). The split
- * constraints are destroyed and replaced by a set of new constraints
- * of the same class. If gts_vertex_encroaches_edge() is used for
- * @encroaches, the resulting surface will be Delaunay conforming.
- *
- * If @steiner_max is positive or nul, the recursive splitting
- * procedure will stop when this maximum number of Steiner points is
- * reached. In that case the resulting surface will not necessarily be
- * Delaunay conforming.
- *
- * Returns: the number of remaining encroached edges. If @steiner_max
- * is set to a negative value and gts_vertex_encroaches_edge() is used
- * for @encroaches this should always be zero. 
- */
-guint gts_delaunay_conform (GtsSurface * surface,
-			    gint steiner_max,
-			    GtsEncroachFunc encroaches,
-			    gpointer data)
-{
-  GtsFifo * encroached;
-  gpointer datas[4];
-  guint encroached_number;
-
-  g_return_val_if_fail (surface != NULL, 0);
-  g_return_val_if_fail (surface != NULL, 0);
-  g_return_val_if_fail (encroaches != NULL, 0);
-
-  datas[0] = encroached = gts_fifo_new ();
-  datas[1] = surface;
-  datas[2] = encroaches;
-  datas[3] = data;
-  gts_surface_foreach_edge (surface, (GtsFunc) make_encroached_fifo, datas);
-
-  split_encroached (surface, 
-		    encroached, 
-		    steiner_max,
-		    encroaches, data);
-  gts_fifo_foreach (encroached, (GtsFunc) gts_object_reset_reserved, NULL);
-  encroached_number = gts_fifo_size (encroached);
-  gts_fifo_destroy (encroached);
-  return encroached_number;
-}
-
-#define EHEAP_PAIR(f) (GTS_OBJECT (f)->reserved)
-
-static void heap_surface_add_face (GtsSurface * s, GtsFace * f)
-{
-  GtsEHeap * heap = GTS_OBJECT (s)->reserved;
-  gdouble key = gts_eheap_key (heap, f);
-
-  if (key != 0.)
-    EHEAP_PAIR (f) = gts_eheap_insert_with_key (heap, f, key);
-  
-  if (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass->parent_class)->add_face)
-    (* GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass->parent_class)->add_face) 
-      (s, f);
-}
-
-static void heap_surface_remove_face (GtsSurface * s, GtsFace * f)
-{
-  GtsEHeap * heap = GTS_OBJECT (s)->reserved;
-
-  if (EHEAP_PAIR (f))
-    gts_eheap_remove (heap, EHEAP_PAIR (f));
-
-  if (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass->parent_class)->remove_face)
-    (* GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass->parent_class)->remove_face) 
-      (s, f);
-}
-
-static void heap_surface_class_init (GtsSurfaceClass * klass)
-{
-  klass->add_face = heap_surface_add_face;
-  klass->remove_face = heap_surface_remove_face;
-}
-
-static GtsObjectClass * heap_surface_class_new (GtsObjectClass * parent_class)
-{
-  GtsObjectClassInfo heap_surface_info;
-
-  heap_surface_info = parent_class->info;
-  heap_surface_info.class_init_func = (GtsObjectClassInitFunc)
-    heap_surface_class_init;
-  return gts_object_class_new (parent_class,
-			       &heap_surface_info);
-}
-
-static void make_face_heap (GtsFace * f, GtsEHeap * heap)
-{
-  gdouble key = gts_eheap_key (heap, f);
-
-  if (key != 0.)
-    EHEAP_PAIR (f) = gts_eheap_insert_with_key (heap, f, key);
-}
-
-/**
- * gts_delaunay_refine:
- * @surface: a #GtsSurface describing a conforming Delaunay triangulation.
- * @steiner_max: maximum number of Steiner points.
- * @encroaches: a #GtsEncroachFunc.
- * @encroach_data: user-data to pass to @encroaches.
- * @cost: a #GtsKeyFunc used to sort the faces during refinement.
- * @cost_data: user-data to pass to @cost.
- *
- * An implementation of the refinement algorithm described in Ruppert
- * (1995) and Shewchuk (1996).
- * 
- * Returns: the number of unrefined faces of @surface left. Should be zero
- * if @steiner_max is set to a negative value.
- */
-guint gts_delaunay_refine (GtsSurface * surface,
-			   gint steiner_max,
-			   GtsEncroachFunc encroaches,
-			   gpointer encroach_data,
-			   GtsKeyFunc cost,
-			   gpointer cost_data)
-{
-  GtsObjectClass * heap_surface_class;
-  GtsObjectClass * original_class;
-  GtsEHeap * heap;
-  GtsFifo * encroached;
-  GtsFace * f;
-  guint unrefined_number;
-
-  g_return_val_if_fail (surface != NULL, 0);
-  g_return_val_if_fail (encroaches != NULL, 0);
-  g_return_val_if_fail (cost != NULL, 0);
-
-  original_class = GTS_OBJECT (surface)->klass;
-  heap_surface_class = heap_surface_class_new (original_class);
-  GTS_OBJECT (surface)->klass = heap_surface_class;
-
-  heap = gts_eheap_new (cost, cost_data);
-  gts_surface_foreach_face (surface, (GtsFunc) make_face_heap, heap);
-  encroached = gts_fifo_new ();
-  
-  GTS_OBJECT (surface)->reserved = heap;
-
-  while (steiner_max-- != 0 && (f = gts_eheap_remove_top (heap, NULL))) {
-    GtsVertex * c = 
-      GTS_VERTEX (gts_triangle_circumcircle_center (GTS_TRIANGLE (f),
-		  GTS_POINT_CLASS (surface->vertex_class)));
-    EHEAP_PAIR (f) = NULL;
-    g_assert (c != NULL);
-    g_assert (gts_delaunay_add_vertex (surface, c, f) == NULL);
-
-    vertex_encroaches (c, surface, encroached, encroaches, encroach_data);
-    if (!gts_fifo_is_empty (encroached)) {
-      gts_delaunay_remove_vertex (surface, c);
-      steiner_max = split_encroached (surface, 
-				      encroached, 
-				      steiner_max, 
-				      encroaches, 
-				      encroach_data);
-    }
-  }
-
-  unrefined_number = gts_eheap_size (heap);
-  gts_eheap_foreach (heap, (GFunc) gts_object_reset_reserved, NULL);
-  gts_eheap_destroy (heap);
-
-  gts_fifo_foreach (encroached, (GtsFunc) gts_object_reset_reserved, NULL);
-  gts_fifo_destroy (encroached);
-
-  GTS_OBJECT (surface)->klass = original_class;
-  GTS_OBJECT (surface)->reserved = NULL;
-  g_free (heap_surface_class);
-
-  return unrefined_number;
-}
diff --git a/src/gts/rounding.h b/src/gts/rounding.h
deleted file mode 100644
index 053b32f..0000000
--- a/src/gts/rounding.h
+++ /dev/null
@@ -1,85 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include "config.h"
-
-#ifdef HAVE_FPU_CONTROL_H
-#  include <fpu_control.h>
-#  ifdef _FPU_EXTENDED
-#   if !defined(__alpha__) || !defined(__GLIBC__)
-#    if defined(__arm__)
-     static fpu_control_t fpu_round_double = _FPU_DEFAULT;
-#    else
-     static fpu_control_t fpu_round_double =
-       (_FPU_DEFAULT & ~ _FPU_EXTENDED)|_FPU_DOUBLE;
-#    endif
-     static fpu_control_t fpu_init;
-#    define FPU_ROUND_DOUBLE  { _FPU_GETCW(fpu_init);\
-                                _FPU_SETCW(fpu_round_double); }
-#    define FPU_RESTORE       {_FPU_SETCW(fpu_init);}
-#   else /* __alpha__ && __GLIBC__ */
-#    define FPU_ROUND_DOUBLE
-#    define FPU_RESTORE
-#   endif /* __alpha__ && __GLIBC__ */
-#  else /* not FPU_EXTENDED */
-#    define FPU_ROUND_DOUBLE
-#    define FPU_RESTORE
-#  endif /* not FPU_EXTENDED */
-#else /* not HAVE_FPU_CONTROL_H */
-#  ifdef __FreeBSD__
-#    include <floatingpoint.h>
-#    define FPU_ROUND_DOUBLE  (fpsetprec(FP_PD))
-#    define FPU_RESTORE       (fpsetprec(FP_PE))
-#  else /* not __FreeBSD__ */
-#    ifdef WIN32
-#      ifdef _MSC_VER
-#        include <float.h>
-         static unsigned int fpu_init;
-#        define FPU_ROUND_DOUBLE (fpu_init = _controlfp (0, 0),\
-                                 _controlfp (_PC_53, MCW_PC))
-#        define FPU_RESTORE      (_controlfp (fpu_init, 0xfffff))
-#      elif __MINGW32__
-#        include <float.h>
-         static unsigned int fpu_init;
-#        define FPU_ROUND_DOUBLE (fpu_init = _controlfp (0, 0),\
-                                  _controlfp (_PC_53, _MCW_PC))
-#        define FPU_RESTORE      (_controlfp (fpu_init, 0xfffff))
-#      else /* not _MSC_VER or __MINGW32__ */
-#        error "You need MSVC or MinGW for the Win32 version"
-#      endif /*  not _MSC_VER or __MINGW32__ */
-#    else /* not WIN32 */
-#      ifdef __CYGWIN__
-         typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__HI__)));
-         static fpu_control_t fpu_round_double = 0x027f;
-         static fpu_control_t fpu_init;
-#        define _FPU_GETCW(cw) __asm__ ("fnstcw %0" : "=m" (*&cw))
-#        define _FPU_SETCW(cw) __asm__ ("fldcw %0" : : "m" (*&cw))
-#        define FPU_ROUND_DOUBLE  { _FPU_GETCW(fpu_init);\
-                                    _FPU_SETCW(fpu_round_double); }
-#        define FPU_RESTORE       { _FPU_SETCW(fpu_init);}
-#      else /* not __CYGWIN__ */
-#        ifdef CPP_HAS_WARNING
-#          warning "Unknown CPU: assuming default double precision rounding"
-#        endif /* CPP_HAS_WARNING */
-#        define FPU_ROUND_DOUBLE
-#        define FPU_RESTORE
-#      endif /* not __CYGWIN__ */
-#    endif /* not WIN32 */
-#  endif /* not __FreeBSD__ */
-#endif /* not HAVE_FPU_CONTROL_H */
diff --git a/src/gts/segment.c b/src/gts/segment.c
deleted file mode 100644
index 58a0540..0000000
--- a/src/gts/segment.c
+++ /dev/null
@@ -1,233 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include "gts.h"
-
-static void segment_destroy (GtsObject * object)
-{
-  GtsSegment * segment = GTS_SEGMENT (object);
-  GtsVertex * v1 = segment->v1;
-  GtsVertex * v2 = segment->v2;
-
-  v1->segments = g_slist_remove (v1->segments, segment);
-  if (!GTS_OBJECT_DESTROYED (v1) &&
-      !gts_allow_floating_vertices && v1->segments == NULL)
-    gts_object_destroy (GTS_OBJECT (v1));
-
-  v2->segments = g_slist_remove (v2->segments, segment);
-  if (!GTS_OBJECT_DESTROYED (v2) &&
-      !gts_allow_floating_vertices && v2->segments == NULL)
-    gts_object_destroy (GTS_OBJECT (v2));
-
-  (* GTS_OBJECT_CLASS (gts_segment_class ())->parent_class->destroy) (object);
-}
-
-static void segment_class_init (GtsObjectClass * klass)
-{
-  klass->destroy = segment_destroy;
-}
-
-static void segment_init (GtsSegment * segment)
-{
-  segment->v1 = segment->v2 = NULL;
-}
-
-/**
- * gts_segment_class:
- *
- * Returns: the #GtsSegmentClass.
- */
-GtsSegmentClass * gts_segment_class (void)
-{
-  static GtsSegmentClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo segment_info = {
-      "GtsSegment",
-      sizeof (GtsSegment),
-      sizeof (GtsSegmentClass),
-      (GtsObjectClassInitFunc) segment_class_init,
-      (GtsObjectInitFunc) segment_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (gts_object_class (), 
-				  &segment_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_segment_new:
- * @klass: a #GtsSegmentClass.
- * @v1: a #GtsVertex.
- * @v2: another #GtsVertex different from @v1.
- *
- * Returns: a new #GtsSegment linking @v1 and @v2.
- */
-GtsSegment * gts_segment_new (GtsSegmentClass * klass, 
-			      GtsVertex * v1, GtsVertex * v2)
-{
-  GtsSegment * s;
-
-  g_return_val_if_fail (v1 != NULL, NULL);
-  g_return_val_if_fail (v2 != NULL, NULL);
-  g_return_val_if_fail (v1 != v2, NULL);
-
-  s = GTS_SEGMENT (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  s->v1 = v1;
-  s->v2 = v2;
-  v1->segments = g_slist_prepend (v1->segments, s);
-  v2->segments = g_slist_prepend (v2->segments, s);
-  
-  return s;
-}
-
-/**
- * gts_segment_is_duplicate:
- * @s: a #GtsSegment.
- *
- * Returns: the first #GtsSegment different from @s which shares the
- * same endpoints or %NULL if there is none.
- */
-GtsSegment * gts_segment_is_duplicate (GtsSegment * s)
-{
-  GSList * i;
-  GtsVertex * v2;
-
-  g_return_val_if_fail (s != NULL, NULL);
-
-  v2 = s->v2;
-  i = s->v1->segments;
-  if (s->v1 == v2) /* s is degenerate: special treatment */
-    while (i) {
-      GtsSegment * s1 = i->data;
-      if (s1 != s && s1->v1 == v2 && s1->v2 == v2)
-	return s1;
-      i = i->next;
-    }
-  else /* s is not degenerate */
-    while (i) {
-      GtsSegment * s1 = i->data;
-      if (s1 != s && (s1->v1 == v2 || s1->v2 == v2))
-	return s1;
-      i = i->next;
-    }
-  return NULL;
-}
-
-/**
- * gts_segments_are_intersecting:
- * @s1: a #GtsSegment.
- * @s2: a #GtsSegment.
- *
- * Returns: %GTS_IN if @s1 and @s2 are intersecting, %GTS_ON if one of the
- * endpoints of @s1 (resp. @s2) lies on @s2 (resp. @s1), %GTS_OUT otherwise.
- */
-GtsIntersect gts_segments_are_intersecting (GtsSegment * s1, GtsSegment * s2)
-{
-  GtsPoint * p1, * p2, * p3, * p4;
-  gdouble d1, d2, d3, d4;
-
-  g_return_val_if_fail (s1 != NULL && s2 != NULL, FALSE);
-
-  p1 = GTS_POINT (s1->v1); p2 = GTS_POINT (s1->v2);
-  p3 = GTS_POINT (s2->v1); p4 = GTS_POINT (s2->v2);
-  d1 = gts_point_orientation (p1, p2, p3);
-  d2 = gts_point_orientation (p1, p2, p4);
-  if ((d1 > 0.0 && d2 > 0.0) ||
-      (d1 < 0.0 && d2 < 0.0))
-    return GTS_OUT;
-  d3 = gts_point_orientation (p3, p4, p1);
-  d4 = gts_point_orientation (p3, p4, p2);
-  if ((d3 > 0.0 && d4 > 0.0) ||
-      (d3 < 0.0 && d4 < 0.0))
-    return GTS_OUT;
-  if (d1 == 0.0 || d2 == 0.0 || d3 == 0.0 || d4 == 0.0)
-    return GTS_ON;
-  return GTS_IN;
-}
-
-/**
- * gts_segment_midvertex:
- * @s: a #GtsSegment.
- * @klass: a #GtsVertexClass to be used for the new vertex.
- *
- * Returns: a new #GtsVertex, midvertex of @s.
- */
-GtsVertex * gts_segment_midvertex (GtsSegment * s, GtsVertexClass * klass)
-{
-  GtsPoint * p1, * p2;
-
-  g_return_val_if_fail (s != NULL, NULL);
-  g_return_val_if_fail (klass != NULL, NULL);
-
-  p1 = GTS_POINT (s->v1); p2 = GTS_POINT (s->v2);
-  return gts_vertex_new (klass,
-			 (p1->x + p2->x)/2., 
-			 (p1->y + p2->y)/2.,
-			 (p1->z + p2->z)/2.);
-}
-
-/**
- * gts_segments_from_vertices:
- * @vertices: a list of #GtsVertex.
- * 
- * Returns: a list of unique #GtsSegment which have one of their vertices in 
- * @vertices.
- */
-GSList * gts_segments_from_vertices (GSList * vertices)
-{
-  GHashTable * hash;
-  GSList * segments = NULL, * i;
-
-  hash = g_hash_table_new (NULL, NULL);
-  i = vertices;
-  while (i) {
-    GSList * j = GTS_VERTEX (i->data)->segments;
-    while (j) {
-      GtsSegment * s = j->data;
-      if (g_hash_table_lookup (hash, s) == NULL) {
-	segments = g_slist_prepend (segments, s);
-	g_hash_table_insert (hash, s, i);
-      }
-      j = j->next;
-    }
-    i = i->next;
-  }
-  g_hash_table_destroy (hash);
-  return segments;
-}
-
-/**
- * gts_segment_is_ok:
- * @s: a #GtsSegment.
- * 
- * Returns: %TRUE if @s is not degenerate (i.e. @s->v1 != @s->v2) and not 
- * duplicate, %FALSE otherwise.
- */
-gboolean gts_segment_is_ok (GtsSegment * s)
-{
-  g_return_val_if_fail (s != NULL, FALSE);
-  g_return_val_if_fail (s->v1 != s->v2, FALSE);
-  g_return_val_if_fail (!gts_segment_is_duplicate (s), FALSE);
-  g_return_val_if_fail (GTS_OBJECT (s)->reserved == NULL, FALSE);
-  return TRUE;
-}
diff --git a/src/gts/split.c b/src/gts/split.c
deleted file mode 100644
index 8283e17..0000000
--- a/src/gts/split.c
+++ /dev/null
@@ -1,1840 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <stdlib.h>
-#include <string.h>
-#include "gts.h"
-
-#define DYNAMIC_SPLIT
-#define NEW
-
-/* #define DEBUG
-   #define DEBUG_HEXPAND
-   #define DEBUG_EXPAND */
-
-struct _GtsSplitCFace {
-  GtsFace * f;
-  GtsTriangle ** a1, ** a2;
-};
-
-typedef struct _CFace      CFace;
-typedef struct _CFaceClass CFaceClass;
-
-struct _CFace {
-  GtsObject object; 
-
-  GtsSplit * parent_split;
-  GtsTriangle * t;
-  guint flags;
-};
-/* the size of the CFace structure must be smaller or equal to the size
-   of the GtsFace structure as both structures use the same memory location */
-
-struct _CFaceClass {
-  GtsObjectClass parent_class;
-};
-
-#define IS_CFACE(obj) (gts_object_is_from_class (obj, cface_class ()))
-#define CFACE(obj)    ((CFace *) obj)
-#define CFACE_ORIENTATION(cf) ((cf)->flags & 0x1)
-#define CFACE_ORIENTATION_DIRECT(cf) ((cf)->flags |= 0x1)
-#define CFACE_VVS(cf)                ((cf)->flags & 0x2)
-#define CFACE_VVS_DIRECT(cf)         ((cf)->flags |= 0x2)
-#define CFACE_E1                     0x4
-#define CFACE_E2                     0x8
-#define CFACE_KEEP_VVS               0x10
-
-#define ROTATE_ORIENT(e, e1, e2, e3)  { if (e1 == e) { e1 = e2; e2 = e3; }\
-                                 else if (e2 == e) { e2 = e1; e1 = e3; }\
-                                 else g_assert (e3 == e); }
-#define SEGMENT_USE_VERTEX(s, v) ((s)->v1 == v || (s)->v2 == v)
-#define TRIANGLE_REPLACE_EDGE(t, e, with) { if ((t)->e1 == e)\
-					      (t)->e1 = with;\
-					    else if ((t)->e2 == e)\
-					      (t)->e2 = with;\
-					    else {\
-					      g_assert ((t)->e3 == e);\
-					      (t)->e3 = with;\
-					    }\
-                                          }
-
-#define HEAP_INSERT_OBJECT(h, e) (GTS_OBJECT (e)->reserved =\
-				  gts_eheap_insert (h, e))
-#define HEAP_REMOVE_OBJECT(h, e) (gts_eheap_remove (h, GTS_OBJECT (e)->reserved),\
-				   GTS_OBJECT (e)->reserved = NULL)
-
-static GtsObjectClass * cface_class (void)
-{
-  static GtsObjectClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo cface_info = {
-      "GtsCFace",
-      sizeof (CFace),
-      sizeof (CFaceClass),
-      (GtsObjectClassInitFunc) NULL,
-      (GtsObjectInitFunc) NULL,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (gts_object_class (), &cface_info);
-    g_assert (sizeof (CFace) <= sizeof (GtsFace));
-  }
-
-  return klass;
-}
-
-/* Replace @e with @with for all the triangles using @e but @f.
-   Destroys @e and removes it from @heap (if not %NULL). 
-   Returns a triangle using e different from f or %NULL. */
-static GtsTriangle * replace_edge_collapse (GtsEdge * e, 
-					    GtsEdge * with, 
-					    CFace * cf,
-					    GtsEHeap * heap
-#ifdef DYNAMIC_SPLIT
-					    , GtsTriangle *** a1
-#endif
-#ifdef NEW
-					    , guint edge_flag
-#endif
-					    )
-{
-  GSList * i;
-  GtsTriangle * rt = NULL;
-#ifdef DYNAMIC_SPLIT
-  guint size;
-  GtsTriangle ** a;
-#endif
-
-#ifdef NEW
-  i = e->triangles;
-  e->triangles = NULL;
-  size = g_slist_length (i)*sizeof (GtsTriangle *);
-  *a1 = a = g_malloc (size > 0 ? size : sizeof (GtsTriangle *));
-  while (i) {
-    GtsTriangle * t = i->data;
-    GSList * next = i->next;
-    if (t != ((GtsTriangle *) cf)) {
-      if (IS_CFACE (t)) {
-	i->next = e->triangles;
-	e->triangles = i;
-	/* set the edge given by edge_flag (CFACE_E1 or CFACE_E2) */
-	GTS_OBJECT (t)->reserved = GUINT_TO_POINTER (edge_flag);
-	cf->flags |= CFACE_KEEP_VVS;
-      }
-      else {
-	TRIANGLE_REPLACE_EDGE (t, e, with);
-	i->next = with->triangles;
-	with->triangles = i;
-	rt = t;
-	*(a++) = t;
-      }
-    }
-    else
-      g_slist_free_1 (i);
-    i = next;
-  }
-  *a = NULL;
-  if (!e->triangles) {
-    if (heap)
-      HEAP_REMOVE_OBJECT (heap, e);
-    gts_object_destroy (GTS_OBJECT (e));
-  }
-#else /* not NEW */
-  i = e->triangles;
-#ifdef DYNAMIC_SPLIT
-  size = g_slist_length (i)*sizeof (GtsTriangle *);
-  *a1 = a = g_malloc (size > 0 ? size : sizeof (GtsTriangle *));
-#endif
-  while (i) {
-    GtsTriangle * t = i->data;
-    GSList * next = i->next;
-    if (t != ((GtsTriangle *) cf)) {
-      TRIANGLE_REPLACE_EDGE (t, e, with);
-      i->next = with->triangles;
-      with->triangles = i;
-      rt = t;
-#ifdef DYNAMIC_SPLIT
-      *(a++) = t;
-#endif
-    }
-    else
-      g_slist_free_1 (i);
-    i = next;
-  }
-#ifdef DYNAMIC_SPLIT
-  *a = NULL;
-#endif
-  if (heap)
-    HEAP_REMOVE_OBJECT (heap, e);
-  e->triangles = NULL;
-  gts_object_destroy (GTS_OBJECT (e));
-#endif /* NEW */
-
-  return rt;
-}
-
-static CFace * cface_new (GtsFace * f,
-			  GtsEdge * e,
-			  GtsVertex * v1, 
-			  GtsVertex * v2,
-			  GtsSplit * vs,
-			  GtsEHeap * heap,
-			  GtsEdgeClass * klass
-#ifdef DYNAMIC_SPLIT
-			  , GtsSplitCFace * scf
-#endif
-			  )
-{
-  CFace * cf;
-  GtsVertex * v;
-  GtsEdge * e1, * e2, * e3, * vvs;
-  GSList * i;
-  GtsTriangle * t, * t1 = NULL, * t2 = NULL;
-  guint flags;
-
-  g_return_val_if_fail (f != NULL, NULL);
-#ifndef NEW
-  g_return_val_if_fail (GTS_IS_FACE (f), NULL);
-#endif
-  g_return_val_if_fail (e != NULL, NULL);
-  g_return_val_if_fail (vs != NULL, NULL);
-
-  t = ((GtsTriangle *) f);
-  if (heap)
-    g_return_val_if_fail (!gts_triangle_is_duplicate (t), NULL);
-
-#ifdef NEW
-  /* get CFACE_E1 and CFACE_E2 info */
-  flags = GPOINTER_TO_UINT (GTS_OBJECT (f)->reserved);
-#endif
-  GTS_OBJECT_SET_FLAGS (f, GTS_DESTROYED);
-
-  i = f->surfaces;
-  while (i) {
-    GSList * next = i->next;
-    gts_surface_remove_face (i->data, f);
-    i = next;
-  }
-  g_slist_free (f->surfaces);
-
-  e1 = t->e1; e2 = t->e2; e3 = t->e3;
-  ROTATE_ORIENT (e, e1, e2, e3);
-
-  cf = (CFace *) f;
-#ifndef NEW
-  GTS_OBJECT (cf)->klass = cface_class ();
-#else
-  cf->flags = flags;
-#endif
-  gts_object_init (GTS_OBJECT (cf), cface_class ());
-  cf->parent_split = vs;
-
-  if (SEGMENT_USE_VERTEX (GTS_SEGMENT (e1), v2)) {
-    CFACE_ORIENTATION_DIRECT (cf); /* v1->v2->v */
-    e3 = e1; e1 = e2; e2 = e3;
-  }
-  v = GTS_SEGMENT (e1)->v1 == v1 ?
-    GTS_SEGMENT (e1)->v2 : GTS_SEGMENT (e1)->v1;
-#ifdef NEW
-  if ((cf->flags & CFACE_E1) || (cf->flags & CFACE_E2))
-    g_assert ((vvs = GTS_EDGE (gts_vertices_are_connected (vs->v, v))));
-  else
-#endif
-  vvs = gts_edge_new (klass, v, vs->v);
-
-  t1 = replace_edge_collapse (e1, vvs, cf, heap
-#ifdef DYNAMIC_SPLIT
-			      , &scf->a1
-#endif
-#ifdef NEW
-			      , CFACE_E1
-#endif
-			      );
-  t2 = replace_edge_collapse (e2, vvs, cf, heap
-#ifdef DYNAMIC_SPLIT
-			      , &scf->a2
-#endif
-#ifdef NEW
-			      , CFACE_E2
-#endif
-			      );
-  t = cf->t = t1 ? t1 : t2;
-  g_assert (t);
-
-  /* set up flags necessary to find vvs */
-  if (t->e1 == vvs) e2 = t->e2;
-  else if (t->e2 == vvs) e2 = t->e3;
-  else {
-    g_assert (t->e3 == vvs);
-    e2 = t->e1;
-  }
-  if (SEGMENT_USE_VERTEX (GTS_SEGMENT (e2), v))
-    CFACE_VVS_DIRECT (cf);
-
-  return cf;
-}
-
-static void find_vvs (GtsVertex * vs,
-		      GtsTriangle * t,
-		      GtsVertex ** v, GtsEdge ** vvs,
-		      gboolean orientation)
-{
-  GtsEdge * e1 = t->e1, * e2 = t->e2, * e3 = t->e3, * tmp;
-
-  if (SEGMENT_USE_VERTEX (GTS_SEGMENT (e2), vs)) {
-    tmp = e1; e1 = e2; e2 = e3; e3 = tmp;
-  }
-  else if (SEGMENT_USE_VERTEX (GTS_SEGMENT (e3), vs)) {
-    tmp = e1; e1 = e3; e3 = e2; e2 = tmp;
-  }
-  else
-    g_assert (SEGMENT_USE_VERTEX (GTS_SEGMENT (e1), vs));
-  if (SEGMENT_USE_VERTEX (GTS_SEGMENT (e2), vs) ||
-      !gts_segments_touch (GTS_SEGMENT (e1), GTS_SEGMENT (e2))) {
-    tmp = e1; e1 = e2; e2 = e3; e3 = tmp;
-    g_assert (gts_segments_touch (GTS_SEGMENT (e1), GTS_SEGMENT (e2)));
-  }
-
-  *vvs = orientation ? e1 : e3;
-
-  if (GTS_SEGMENT (*vvs)->v1 != vs) {
-    g_assert (GTS_SEGMENT (*vvs)->v2 == vs);
-    *v = GTS_SEGMENT (*vvs)->v1;
-  }
-  else
-    *v = GTS_SEGMENT (*vvs)->v2;
-}
-
-static void replace_edge_expand (GtsEdge * e, 
-				 GtsEdge * with,
-				 GtsTriangle ** a,
-				 GtsVertex * v)
-{
-  GtsTriangle ** i = a, * t;
-
-  while ((t = *(i++))) {
-#ifdef DEBUG_EXPAND
-    g_assert (!IS_CFACE (t));
-    fprintf (stderr, "replacing %p->%d: e: %p->%d with: %p->%d\n",
-	     t, id (t), e, id (e), with, id (with));
-#endif
-    TRIANGLE_REPLACE_EDGE (t, e, with);
-    with->triangles = g_slist_prepend (with->triangles, t);
-    if (GTS_OBJECT (t)->reserved) {
-      /* apart from the triangles having e as an edge, t is the only
-	 triangle using v */
-      g_assert (GTS_OBJECT (t)->reserved == v);
-      GTS_OBJECT (t)->reserved = NULL;
-    }
-    else
-      GTS_OBJECT (t)->reserved = v;
-  }
-}
-
-static void cface_expand (CFace * cf,
-			  GtsTriangle ** a1,
-			  GtsTriangle ** a2,
-			  GtsEdge * e,
-			  GtsVertex * v1, 
-			  GtsVertex * v2,
-			  GtsVertex * vs,
-			  GtsEdgeClass * klass)
-{
-  GtsVertex * v;
-  GtsEdge * e1, * e2, * vvs;
-  gboolean orientation;
-  guint flags;
-
-  g_return_if_fail (cf != NULL);
-  g_return_if_fail (IS_CFACE (cf));
-  g_return_if_fail (e != NULL);
-  g_return_if_fail (vs != NULL);
-
-  flags = cf->flags;
-  orientation = CFACE_ORIENTATION (cf);
-
-  find_vvs (vs, cf->t, &v, &vvs, CFACE_VVS (cf));
-
-#ifdef NEW
-  if (flags & CFACE_E1)
-    e1 = GTS_EDGE (gts_vertices_are_connected (v1, v));
-  else
-    e1 = gts_edge_new (klass, v, v1);
-  if (flags & CFACE_E2)
-    e2 = GTS_EDGE (gts_vertices_are_connected (v2, v));
-  else
-    e2 = gts_edge_new (klass, v, v2);
-#else
-  e1 = gts_edge_new (v, v1);
-  e2 = gts_edge_new (v, v2);
-#endif
-
-  replace_edge_expand (vvs, e1, a1, v1);
-  replace_edge_expand (vvs, e2, a2, v2);
-
-#ifdef NEW
-  if (!(flags & CFACE_KEEP_VVS)) {
-    g_slist_free (vvs->triangles);
-    vvs->triangles = NULL;
-    gts_object_destroy (GTS_OBJECT (vvs));
-  }
-#else
-  g_slist_free (vvs->triangles);
-  vvs->triangles = NULL;
-  gts_object_destroy (GTS_OBJECT (vvs));
-#endif
-
-  /* gts_face_new : because I am "creating" a face */
-  GTS_OBJECT (cf)->klass = GTS_OBJECT_CLASS (gts_face_class ());
-  gts_object_init (GTS_OBJECT (cf), GTS_OBJECT (cf)->klass);
-  
-  if (orientation)
-    gts_triangle_set (GTS_TRIANGLE (cf), e, e2, e1);
-  else
-    gts_triangle_set (GTS_TRIANGLE (cf), e, e1, e2);
-}
-
-static void split_destroy (GtsObject * object)
-{
-  GtsSplit * vs = GTS_SPLIT (object);
-  guint i = vs->ncf;
-  GtsSplitCFace * cf = vs->cfaces;
-
-  while (i--) {
-    if (IS_CFACE (cf->f))
-      gts_object_destroy (GTS_OBJECT (cf->f));
-    g_free (cf->a1);
-    g_free (cf->a2);
-    cf++;
-  }
-  g_free (vs->cfaces);
-
-  if (!gts_allow_floating_vertices && vs->v && vs->v->segments == NULL)
-    gts_object_destroy (GTS_OBJECT (vs->v));
-
-  (* GTS_OBJECT_CLASS (gts_split_class ())->parent_class->destroy) (object);
-}
-
-static void split_class_init (GtsObjectClass * klass)
-{
-  klass->destroy = split_destroy;
-}
-
-static void split_init (GtsSplit * split)
-{
-  split->v1 = split->v2 = NULL;
-  split->v = NULL;
-  split->cfaces = NULL;
-  split->ncf = 0;
-}
-
-/**
- * gts_split_class:
- *
- * Returns: the #GtsSplitClass.
- */
-GtsSplitClass * gts_split_class (void)
-{
-  static GtsSplitClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo split_info = {
-      "GtsSplit",
-      sizeof (GtsSplit),
-      sizeof (GtsSplitClass),
-      (GtsObjectClassInitFunc) split_class_init,
-      (GtsObjectInitFunc) split_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (gts_object_class (), 
-				  &split_info);
-  }
-
-  return klass;
-}
-
-#ifdef DEBUG
-static gboolean edge_collapse_is_valid (GtsEdge * e)
-{
-  GSList * i;
-
-  g_return_val_if_fail (e != NULL, FALSE);
-  
-  if (gts_segment_is_duplicate (GTS_SEGMENT (e))) {
-    g_warning ("collapsing duplicate edge");
-    return FALSE;
-  }
-    
-  i = GTS_SEGMENT (e)->v1->segments;
-  while (i) {
-    GtsEdge * e1 = i->data;
-    if (e1 != e && GTS_IS_EDGE (e1)) {
-      GtsEdge * e2 = NULL;
-      GSList * j = GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e)->v1 ? 
-	GTS_SEGMENT (e1)->v2->segments : GTS_SEGMENT (e1)->v1->segments;
-      while (j && !e2) {
-	GtsEdge * e1 = j->data;
-	if (GTS_IS_EDGE (e1) && 
-	    (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e)->v2 || 
-	     GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e)->v2))
-	  e2 = e1;
-	j = j->next;
-      }
-      if (e2 && !gts_triangle_use_edges (e, e1, e2)) {
-	g_warning ("collapsing empty triangle");
-	return FALSE;
-      }
-    }
-    i = i->next;
-  }
-
-  if (gts_edge_is_boundary (e, NULL)) {
-    GtsTriangle * t = e->triangles->data;
-    if (gts_edge_is_boundary (t->e1, NULL) &&
-	gts_edge_is_boundary (t->e2, NULL) &&
-	gts_edge_is_boundary (t->e3, NULL)) {
-      g_warning ("collapsing single triangle");
-      return FALSE;
-    }
-  }
-  else {
-    if (gts_vertex_is_boundary (GTS_SEGMENT (e)->v1, NULL) &&
-	gts_vertex_is_boundary (GTS_SEGMENT (e)->v2, NULL)) {
-      g_warning ("collapsing two sides of a strip");
-      return FALSE;    
-    }
-    if (gts_edge_belongs_to_tetrahedron (e)) {
-      g_warning ("collapsing tetrahedron");
-      return FALSE;
-    }
-  }
-
-  return TRUE;
-}
-#endif /* DEBUG */
-
-/* Not currently used.  May be useful for some debug code */
-#ifdef DEBUG
-static void print_split (GtsSplit * vs, FILE * fptr)
-{
-  guint j;
-  GtsSplitCFace * cf;
-
-  g_return_if_fail (vs != NULL);
-  g_return_if_fail (fptr != NULL);
-
-  fprintf (fptr, "%p: v: %p v1: %p v2: %p ncf: %u cfaces: %p\n",
-	   vs, vs->v, vs->v1, vs->v2, vs->ncf, vs->cfaces);
-  cf = vs->cfaces;
-  j = vs->ncf;
-  while (j--) {
-    fprintf (stderr, "  f: %p a1: %p a2: %p\n",
-	     cf->f, cf->a1, cf->a2);
-    cf++;
-  }
-}
-#endif
-
-/**
- * gts_split_collapse:
- * @vs: a #GtsSplit.
- * @klass: a #GtsEdgeClass.
- * @heap: a #GtsEHeap or %NULL.
- *
- * Collapses the vertex split @vs. Any new edge created during the process will
- * be of class @klass. If heap is not %NULL, the new edges will be inserted
- * into it and the destroyed edges will be removed from it.
- */
-void gts_split_collapse (GtsSplit * vs, 
-			 GtsEdgeClass * klass,
-			 GtsEHeap * heap)
-{
-  GtsEdge * e;
-  GtsVertex * v, * v1, * v2;
-  GSList * i, * end;
-#ifdef DYNAMIC_SPLIT
-  GtsSplitCFace * cf;
-  guint j;
-#endif
-#ifdef DEBUG
-  gboolean invalid = FALSE;
-  static guint ninvalid = 0;
-#endif
-
-  g_return_if_fail (vs != NULL);
-  g_return_if_fail (klass != NULL);
-
-  v = vs->v;
-
-  g_return_if_fail (v->segments == NULL);
-  
-  /* we don't want to destroy vertices */
-  gts_allow_floating_vertices = TRUE;
-
-  v1 = GTS_SPLIT_V1 (vs);
-  v2 = GTS_SPLIT_V2 (vs);
-  g_assert ((e = GTS_EDGE (gts_vertices_are_connected (v1, v2))));
-
-#ifdef DEBUG
-  fprintf (stderr, "collapsing %p: v1: %p v2: %p v: %p\n", vs, v1, v2, v);
-  if (!edge_collapse_is_valid (e)) {
-    char fname[80];
-    FILE * fptr;
-    GSList * triangles, * i;
-
-    g_warning ("invalid edge collapse");
-    invalid = TRUE;
-    sprintf (fname, "invalid.%d", ninvalid);
-    fptr = fopen (fname, "wt");
-    gts_write_segment (GTS_SEGMENT (e), GTS_POINT (v), fptr);
-    triangles = gts_vertex_triangles (v1, NULL);
-    triangles = gts_vertex_triangles (v2, triangles);
-    i = triangles;
-    while (i) {
-      gts_write_triangle (i->data, GTS_POINT (v), fptr);
-      i = i->next;
-    }
-    g_slist_free (triangles);
-    fclose (fptr);
-  }
-#endif
-
-  i = e->triangles;
-#ifdef DYNAMIC_SPLIT
-  cf = vs->cfaces;
-  j = vs->ncf;
-  while (j--) {
-    g_free (cf->a1);
-    g_free (cf->a2);
-    cf++;
-  }
-  g_free (vs->cfaces);
-
-  vs->ncf = g_slist_length (i);
-  g_assert (vs->ncf > 0);
-  cf = vs->cfaces = g_malloc (vs->ncf*sizeof (GtsSplitCFace));
-#endif /* DYNAMIC_SPLIT */
-#ifdef NEW
-  while (i) {
-    cf->f = i->data;
-    g_assert (GTS_IS_FACE (cf->f));
-    GTS_OBJECT (cf->f)->klass = GTS_OBJECT_CLASS (cface_class ());
-    cf++;
-    i = i->next;
-  }
-  i = e->triangles;
-  cf = vs->cfaces;
-  while (i) {
-    cface_new (i->data, e, v1, v2, vs, heap, klass, cf);
-#ifdef DEBUG
-    fprintf (stderr, "cface: %p->%d t: %p->%d a1: ", 
-	     cf->f, id (cf->f), CFACE (cf->f)->t, id (CFACE (cf->f)->t));
-    {
-      GtsTriangle * t, ** a;
-      a = cf->a1;
-      while ((t = *(a++)))
-	fprintf (stderr, "%p->%d ", t, id (t));
-      fprintf (stderr, "a2: ");
-      a = cf->a2;
-      while ((t = *(a++)))
-	fprintf (stderr, "%p->%d ", t, id (t));
-      fprintf (stderr, "\n");
-    }
-#endif
-    cf++;
-    i = i->next;
-  }
-#else /* not NEW */
-  while (i) {
-    cface_new (i->data, e, v1, v2, vs, heap
-#ifdef DYNAMIC_SPLIT
-	       , cf
-#endif /* DYNAMIC_SPLIT */
-	       );
-#ifdef DYNAMIC_SPLIT
-    cf->f = i->data;
-    cf++;
-#endif /* DYNAMIC_SPLIT */
-    i = i->next;
-  }
-#endif /* NEW */
-  g_slist_free (e->triangles);
-  e->triangles = NULL;
-  gts_object_destroy (GTS_OBJECT (e));
-
-  gts_allow_floating_vertices = FALSE;
-
-  end = NULL;
-  i = v1->segments;
-  while (i) {
-    GtsSegment * s = i->data;
-    if (s->v1 == v1)
-      s->v1 = v;
-    else
-      s->v2 = v;
-    end = i;
-    i = i->next;
-  }
-  if (end) {
-    end->next = v->segments;
-    v->segments = v1->segments;
-    v1->segments = NULL;
-  }
-
-  end = NULL;
-  i = v2->segments;
-  while (i) {
-    GtsSegment * s = i->data;
-    if (s->v1 == v2)
-      s->v1 = v;
-    else
-      s->v2 = v;
-    end = i;
-    i = i->next;
-  }
-  if (end) {
-    end->next = v->segments;
-    v->segments = v2->segments;
-    v2->segments = NULL;
-  }
-
-#ifdef DEBUG
-  if (invalid) {
-    char fname[80];
-    FILE * fptr;
-    GSList * triangles, * i;
-    GtsSurface * surface = NULL;
-
-    sprintf (fname, "invalid_after.%d", ninvalid);
-    fptr = fopen (fname, "wt");
-    triangles = gts_vertex_triangles (v, NULL);
-    i = triangles;
-    while (i) {
-      GtsTriangle * t = i->data;
-      fprintf (stderr, "checking %p->%d\n", t, id (t));
-      g_assert (GTS_IS_FACE (t));
-      gts_write_triangle (t, GTS_POINT (v), fptr);
-      surface = GTS_FACE (t)->surfaces->data;
-      if (gts_triangle_is_duplicate (t))
-	fprintf (stderr, "%p->%d is duplicate\n", t, id (t));
-      if (gts_segment_is_duplicate (GTS_SEGMENT (t->e1)))
-	fprintf (stderr, "e1 of %p->%d is duplicate\n", t, id (t));
-      if (gts_segment_is_duplicate (GTS_SEGMENT (t->e2)))
-	fprintf (stderr, "e2 of %p->%d is duplicate\n", t, id (t));
-      if (gts_segment_is_duplicate (GTS_SEGMENT (t->e3)))
-	fprintf (stderr, "e3 of %p->%d is duplicate\n", t, id (t));
-      i = i->next;
-    }
-    fclose (fptr);
-    g_slist_free (triangles);
-#if 0
-    gts_split_expand (vs, surface);
-
-    sprintf (fname, "invalid_after_after.%d", ninvalid);
-    fptr = fopen (fname, "wt");
-    triangles = gts_vertex_triangles (v1, NULL);
-    triangles = gts_vertex_triangles (v2, triangles);
-    i = triangles;
-    while (i) {
-      GtsTriangle * t = i->data;
-      gts_write_triangle (t, GTS_POINT (v), fptr);
-      surface = GTS_FACE (t)->surfaces->data;
-      if (gts_triangle_is_duplicate (t))
-	fprintf (stderr, "%p->%d is duplicate\n", t, id (t));
-      if (gts_segment_is_duplicate (GTS_SEGMENT (t->e1)))
-	fprintf (stderr, "e1 of %p->%d is duplicate\n", t, id (t));
-      if (gts_segment_is_duplicate (GTS_SEGMENT (t->e2)))
-	fprintf (stderr, "e2 of %p->%d is duplicate\n", t, id (t));
-      if (gts_segment_is_duplicate (GTS_SEGMENT (t->e3)))
-	fprintf (stderr, "e3 of %p->%d is duplicate\n", t, id (t));
-      i = i->next;
-    }
-    fclose (fptr);
-    g_slist_free (triangles);
-
-    exit (1);
-#endif
-    ninvalid++;
-  }
-#endif
-}
-
-/**
- * gts_split_expand:
- * @vs: a #GtsSplit.
- * @s: a #GtsSurface.
- * @klass: a #GtsEdgeClass.
- *
- * Expands the vertex split @vs adding the newly created faces to @s. Any 
- * new edge will be of class @klass.
- */
-void gts_split_expand (GtsSplit * vs, 
-		       GtsSurface * s,
-		       GtsEdgeClass * klass)
-{
-  GSList * i;
-  GtsEdge * e;
-  GtsVertex * v, * v1, * v2;  
-  gboolean changed = FALSE;
-  GtsSplitCFace * cf;
-  guint j;
-  
-  g_return_if_fail (vs != NULL);
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (klass != NULL);
-
-  /* we don't want to destroy vertices */
-  gts_allow_floating_vertices = TRUE;
-
-  v1 = GTS_SPLIT_V1 (vs);
-  v2 = GTS_SPLIT_V2 (vs);
-  v = vs->v;
-#ifdef DEBUG_EXPAND
-  fprintf (stderr, "expanding %p->%d: v1: %p->%d v2: %p->%d v: %p->%d\n",
-	   vs, id (vs), v1, id (v1), v2, id (v2), v, id (v));
-#endif
-  e = gts_edge_new (klass, v1, v2);
-  cf = vs->cfaces;
-  j = vs->ncf;
-  while (j--) {
-    cface_expand (CFACE (cf->f), cf->a1, cf->a2, e, v1, v2, v, klass);
-    gts_surface_add_face (s, cf->f);
-    cf++;
-  }
-
-  gts_allow_floating_vertices = FALSE;
-
-  /* this part is described by figure "expand.fig" */
-  i = v->segments;
-  while (i) {
-    GtsEdge * e1 = i->data;
-    GtsVertex * with = NULL;
-    GSList * j = e1->triangles, * next = i->next;
-    // fprintf (stderr, "e1: %p->%d\n", e1, id (e1));
-    while (j && !with) {
-      with = GTS_OBJECT (j->data)->reserved;
-      j = j->next;
-    }
-    if (with) {
-      j = e1->triangles;
-      while (j) {
-	GtsTriangle * t = j->data;
-	if (GTS_OBJECT (t)->reserved) {
-	  g_assert (GTS_OBJECT (t)->reserved == with);
-	  GTS_OBJECT (t)->reserved = NULL;
-	}
-	else
-	  GTS_OBJECT (t)->reserved = with;
-	j = j->next;
-      }
-      if (GTS_SEGMENT (e1)->v1 == v)
-	GTS_SEGMENT (e1)->v1 = with;
-      else
-	GTS_SEGMENT (e1)->v2 = with;
-
-      v->segments = g_slist_remove_link (v->segments, i);
-      i->next = with->segments;
-      with->segments = i;
-      changed = TRUE;
-    }
-    if (next)
-      i = next;
-    else {
-      /* check for infinite loop (the crossed out case in 
-	 figure "expand.fig") */
-      g_assert (changed);
-      changed = FALSE;
-      i = v->segments;
-    }
-  }
-}
-
-#ifndef DYNAMIC_SPLIT
-static void cface_neighbors (GtsSplitCFace * cf,
-			     GtsEdge * e,
-			     GtsVertex * v1,
-			     GtsVertex * v2)
-{
-  GtsTriangle * t = GTS_TRIANGLE (cf->f), ** a;
-  GtsEdge * e1 = t->e1, * e2 = t->e2, * e3 = t->e3;
-  GSList * i;
-  guint size;
-
-  ROTATE_ORIENT (e, e1, e2, e3);
-  if (SEGMENT_USE_VERTEX (GTS_SEGMENT (e1), v2)) {
-    e3 = e1; e1 = e2; e2 = e3;
-  }
-  
-  i = e1->triangles;
-  size = g_slist_length (i)*sizeof (GtsTriangle *);
-  a = cf->a1 = g_malloc (size > 0 ? size : sizeof (GtsTriangle *));
-  while (i) {
-    if (i->data != t)
-      *(a++) = i->data;
-    i = i->next;
-  }
-  *a = NULL;
-
-  i = e2->triangles;
-  size = g_slist_length (i)*sizeof (GtsTriangle *);
-  a = cf->a2 = g_malloc (size > 0 ? size : sizeof (GtsTriangle *));
-  while (i) {
-    if (i->data != t)
-      *(a++) = i->data;
-    i = i->next;
-  }
-  *a = NULL;
-}
-#endif /*ifndef DYNAMIC_SPLIT */
-
-/**
- * gts_split_new:
- * @klass: a #GtsSplitClass.
- * @v: a #GtsVertex.
- * @o1: either a #GtsVertex or a #GtsSplit.
- * @o2: either a #GtsVertex or a #GtsSplit.
- *
- * Creates a new #GtsSplit which would collapse @o1 and @o2 into @v. The 
- * collapse itself is not performed.
- *
- * Returns: the new #GtsSplit.
- */
-GtsSplit * gts_split_new (GtsSplitClass * klass,
-			  GtsVertex * v,
-			  GtsObject * o1,
-			  GtsObject * o2)
-{
-  GtsSplit * vs;
-  GtsVertex * v1, * v2;
-#ifndef DYNAMIC_SPLIT
-  GtsEdge * e;
-  GSList * i;
-  GtsSplitCFace * cf;
-#endif
-
-  g_return_val_if_fail (klass != NULL, NULL);
-  g_return_val_if_fail (v != NULL, NULL);
-  g_return_val_if_fail (GTS_IS_SPLIT (o1) || GTS_IS_VERTEX (o1), NULL);
-  g_return_val_if_fail (GTS_IS_SPLIT (o2) || GTS_IS_VERTEX (o2), NULL);
-
-  vs = GTS_SPLIT (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  vs->v = v;
-  vs->v1 = o1;
-  vs->v2 = o2;
-  v1 = GTS_SPLIT_V1 (vs);
-  v2 = GTS_SPLIT_V2 (vs);
-#ifdef DYNAMIC_SPLIT
-  vs->ncf = 0;
-  vs->cfaces = NULL;
-#else
-  g_assert ((e = GTS_EDGE (gts_vertices_are_connected (v1, v2))));
-  i = e->triangles;
-  vs->ncf = g_slist_length (i);
-  g_assert (vs->ncf > 0);
-  cf = vs->cfaces = g_malloc (vs->ncf*sizeof (GtsSplitCFace));
-  while (i) {
-    cf->f = i->data;
-    cface_neighbors (cf, e, v1, v2);
-    i = i->next;
-    cf++;
-  }
-#endif
-  
-  return vs;
-}
-
-static gboolean 
-split_traverse_pre_order (GtsSplit *           vs,
-			  GtsSplitTraverseFunc func,
-			  gpointer	       data)
-{
-  if (func (vs, data))
-    return TRUE;
-  if (GTS_IS_SPLIT (vs->v1) &&
-      split_traverse_pre_order (GTS_SPLIT (vs->v1), func, data))
-    return TRUE;
-  if (GTS_IS_SPLIT (vs->v2) &&
-      split_traverse_pre_order (GTS_SPLIT (vs->v2), func, data))
-    return TRUE;
-  return FALSE;
-}
-
-static gboolean 
-split_depth_traverse_pre_order (GtsSplit *             vs,
-				guint                  depth,
-				GtsSplitTraverseFunc   func,
-				gpointer	       data)
-{
-  if (func (vs, data))
-      return TRUE;
-    
-  depth--;
-  if (!depth)
-    return FALSE;
-
-  if (GTS_IS_SPLIT (vs->v1) &&
-      split_depth_traverse_pre_order (GTS_SPLIT (vs->v1), depth, func, data))
-    return TRUE;
-  if (GTS_IS_SPLIT (vs->v2) &&
-      split_depth_traverse_pre_order (GTS_SPLIT (vs->v2), depth, func, data))
-    return TRUE;
-  return FALSE;
-}
-
-static gboolean 
-split_traverse_post_order (GtsSplit *           vs,
-			   GtsSplitTraverseFunc func,
-			   gpointer	        data)
-{
-  if (GTS_IS_SPLIT (vs->v1) &&
-      split_traverse_post_order (GTS_SPLIT (vs->v1), func, data))
-    return TRUE;
-  if (GTS_IS_SPLIT (vs->v2) &&
-      split_traverse_post_order (GTS_SPLIT (vs->v2), func, data))
-    return TRUE;
-  if (func (vs, data))
-    return TRUE;
-  return FALSE;
-}
-
-static gboolean
-split_depth_traverse_post_order (GtsSplit *           vs,
-				 guint                depth,
-				 GtsSplitTraverseFunc func,
-				 gpointer	      data)
-{
-  depth--;
-  if (depth) {
-    if (GTS_IS_SPLIT (vs->v1) &&
-	split_depth_traverse_post_order (GTS_SPLIT (vs->v1), 
-					 depth, func, data))
-      return TRUE;
-    if (GTS_IS_SPLIT (vs->v2) &&
-	split_depth_traverse_post_order (GTS_SPLIT (vs->v2),
-					 depth, func, data))
-      return TRUE;
-  }
-  if (func (vs, data))
-    return TRUE;
-  return FALSE;
-}
-
-/**
- * gts_split_traverse:
- * @root: the #GtsSplit to start the traversal from.
- * @order: the order in which nodes are visited - G_PRE_ORDER or G_POST_ORDER.
- * @depth: the maximum depth of the traversal. Nodes below this depth
- * will not be visited. If depth is -1 all nodes in the tree are
- * visited. If depth is 1, only the root is visited. If depth is 2,
- * the root and its children are visited. And so on.
- * @func: the function to call for each visited #GtsHSplit.
- * @data: user data to pass to the function.
- *
- * Traverses the #GtsSplit tree having @root as root. Calls @func for each
- * #GtsSplit of the tree in the order specified by @order. If order is set
- * to G_PRE_ORDER @func is called for the #GtsSplit then its children, if order
- * is set to G_POST_ORDER @func is called for the children and then for the
- * #GtsSplit.
- */
-void gts_split_traverse (GtsSplit *           root,
-			 GTraverseType        order,
-			 gint                 depth,
-			 GtsSplitTraverseFunc func,
-			 gpointer             data)
-{
-  g_return_if_fail (root != NULL);
-  g_return_if_fail (func != NULL);
-  g_return_if_fail (order < G_LEVEL_ORDER);
-  g_return_if_fail (depth == -1 || depth > 0);
-
-  switch (order) {
-  case G_PRE_ORDER:
-    if (depth < 0)
-      split_traverse_pre_order (root, func, data);
-    else
-      split_depth_traverse_pre_order (root, depth, func, data);
-    break;
-  case G_POST_ORDER:
-    if (depth < 0)
-      split_traverse_post_order (root, func, data);
-    else
-      split_depth_traverse_post_order (root, depth, func, data);
-    break;
-  default:
-    g_assert_not_reached ();
-  }
-}
-
-/**
- * gts_split_height:
- * @root: a #GtsSplit.
- *
- * Returns: the maximum height of the vertex split tree having @root as root.
- */
-guint gts_split_height (GtsSplit * root)
-{
-  guint height = 0, tmp_height;
-
-  g_return_val_if_fail (root != NULL, 0);
-
-  if (GTS_IS_SPLIT (root->v1)) {
-    tmp_height = gts_split_height (GTS_SPLIT (root->v1));
-    if (tmp_height > height)
-      height = tmp_height;
-  }
-  if (GTS_IS_SPLIT (root->v2)) {
-    tmp_height = gts_split_height (GTS_SPLIT (root->v2));
-    if (tmp_height > height)
-      height = tmp_height;
-  }
-
-  return height + 1;
-}
-
-#ifndef DYNAMIC_SPLIT
-static gboolean list_array_are_identical (GSList * list, 
-					  gpointer * array,
-					  gpointer excluded)
-{
-  while (list) {
-    gpointer data = list->data;
-    if (data != excluded) {
-      gboolean found = FALSE;
-      gpointer * a = array;
-      
-      while (!found && *a)
-	if (*(a++) == data)
-	  found = TRUE;
-      if (!found)
-	return FALSE;
-    }
-    list = list->next;
-  }
-  return TRUE;
-}
-#endif /* ifndef DYNAMIC_SPLIT */
-
-#ifndef NEW
-gboolean gts_split_is_collapsable (GtsSplit * vs)
-{
-  guint i;
-  GtsSplitCFace * cf;
-  GtsVertex * v1, * v2;
-  GtsEdge * e;
-
-  g_return_val_if_fail (vs != NULL, FALSE);
-
-  v1 = GTS_SPLIT_V1 (vs);
-  v2 = GTS_SPLIT_V2 (vs);
-  g_return_val_if_fail ((e = GTS_EDGE (gts_vertices_are_connected (v1, v2))),
-			FALSE);
-
-#ifdef DYNAMIC_SPLIT
-  if (!gts_edge_collapse_is_valid (e))
-    return FALSE;
-#else 
-  i = vs->ncf;
-  cf = vs->cfaces;
-  while (i--) {
-    GtsTriangle * t = GTS_TRIANGLE (cf->f);
-    GtsEdge * e1 = t->e1, * e2 = t->e2, * e3 = t->e3;
-
-    ROTATE_ORIENT (e, e1, e2, e3);
-    if (SEGMENT_USE_VERTEX (GTS_SEGMENT (e1), v2)) {
-      e3 = e1; e1 = e2; e2 = e3;
-    }
-
-    if (!list_array_are_identical (e1->triangles, (gpointer *) cf->a1, t))
-      return FALSE;
-    if (!list_array_are_identical (e2->triangles, (gpointer *) cf->a2, t))
-      return FALSE;
-    
-    cf++;
-  }
-#endif
-  return TRUE;
-}
-#endif /* not NEW */
-
-#ifdef DEBUG_HEXPAND
-static guint expand_level = 0;
-
-static void expand_indent (FILE * fptr)
-{
-  guint i = expand_level;
-  while (i--)
-    fputc (' ', fptr);
-}
-#endif
-
-/**
- * gts_hsplit_force_expand:
- * @hs: a #GtsHSplit.
- * @hsurface: a #GtsHSurface.
- *
- * Forces the expansion of @hs by first expanding all its dependencies not
- * already expanded.
- */
-void gts_hsplit_force_expand (GtsHSplit * hs,
-			      GtsHSurface * hsurface)
-{
-  guint i;
-  GtsSplitCFace * cf;
-
-  g_return_if_fail (hs != NULL);
-  g_return_if_fail (hsurface != NULL);
-  g_return_if_fail (hs->nchild == 0);
-
-#ifdef DEBUG_HEXPAND
-  expand_level += 2;
-#endif
-
-  if (hs->parent && hs->parent->nchild == 0) {
-#ifdef DEBUG_HEXPAND
-    expand_indent (stderr); 
-    fprintf (stderr, "expand parent %p\n", hs->parent);
-#endif
-    gts_hsplit_force_expand (hs->parent, hsurface);
-  }
-
-  i = GTS_SPLIT (hs)->ncf;
-  cf = GTS_SPLIT (hs)->cfaces;
-  while (i--) {
-    GtsTriangle ** j, * t;
-
-    j = cf->a1;
-    while ((t = *(j++)))
-      if (IS_CFACE (t)) {
-#ifdef DEBUG_HEXPAND
-	expand_indent (stderr); 
-	fprintf (stderr, "expand a1: cf->f: %p t: %p parent_split: %p\n", 
-		 cf->f,
-		 t,
-		 GTS_HSPLIT (CFACE (t)->parent_split));
-#endif
-	gts_hsplit_force_expand (GTS_HSPLIT (CFACE (t)->parent_split),
-				 hsurface);
-#ifdef DEBUG_HEXPAND
-	g_assert (!IS_CFACE (t));
-#endif
-      }
-    j = cf->a2;
-    while ((t = *(j++)))
-      if (IS_CFACE (t)) {
-#ifdef DEBUG_HEXPAND
-	expand_indent (stderr); 
-	fprintf (stderr, "expand a2: cf->f: %p t: %p parent_split: %p\n", 
-		 cf->f,
-		 t,
-		 GTS_HSPLIT (CFACE (t)->parent_split));
-#endif
-	gts_hsplit_force_expand (GTS_HSPLIT (CFACE (t)->parent_split),
-				 hsurface);
-      }
-    cf++;
-  }
-
-  gts_hsplit_expand (hs, hsurface);
-
-#ifdef DEBUG_HEXPAND
-  expand_level -= 2; 
-  expand_indent (stderr); 
-  fprintf (stderr, "%p expanded\n", hs);
-#endif
-}
-
-static void index_object (GtsObject * o, guint * n)
-{
-  o->reserved = GUINT_TO_POINTER ((*n)++);
-}
-
-static void index_face (GtsFace * f, gpointer * data)
-{
-  guint * nf = data[1];
-
-  g_hash_table_insert (data[0], f, GUINT_TO_POINTER ((*nf)++));
-}
-
-/**
- * gts_psurface_write:
- * @ps: a #GtsPSurface.
- * @fptr: a file pointer.
- *
- * Writes to @fptr a GTS progressive surface description.
- */
-void gts_psurface_write (GtsPSurface * ps, FILE * fptr)
-{
-  guint nv = 1;
-  guint nf = 1;
-  GHashTable * hash;
-  gpointer data[2];
-
-  g_return_if_fail (ps != NULL);
-  g_return_if_fail (fptr != NULL);
-  g_return_if_fail (GTS_PSURFACE_IS_CLOSED (ps));
-
-  while (gts_psurface_remove_vertex (ps))
-    ;
-
-  GTS_POINT_CLASS (ps->s->vertex_class)->binary = FALSE;
-  gts_surface_write (ps->s, fptr);
-  
-  gts_surface_foreach_vertex (ps->s, (GtsFunc) index_object, &nv);
-  hash = g_hash_table_new (NULL, NULL);
-  data[0] = hash;
-  data[1] = &nf;
-  gts_surface_foreach_face (ps->s, (GtsFunc) index_face, data);
-
-  fprintf (fptr, "%u\n", ps->split->len);
-  while (ps->pos) {
-    GtsSplit * vs = g_ptr_array_index (ps->split, --ps->pos);
-    GtsSplitCFace * scf = vs->cfaces;
-    GtsVertex * v1, * v2;
-    guint i = vs->ncf;
-
-    fprintf (fptr, "%u %u",
-	     GPOINTER_TO_UINT (GTS_OBJECT (vs->v)->reserved),
-	     vs->ncf);
-    if (GTS_OBJECT (vs)->klass->write)
-      (*GTS_OBJECT (vs)->klass->write) (GTS_OBJECT (vs), fptr);
-    fputc ('\n', fptr);
-
-    v1 = GTS_IS_SPLIT (vs->v1) ? GTS_SPLIT (vs->v1)->v : GTS_VERTEX (vs->v1);
-    GTS_OBJECT (v1)->reserved = GUINT_TO_POINTER (nv++);
-    v2 = GTS_IS_SPLIT (vs->v2) ? GTS_SPLIT (vs->v2)->v : GTS_VERTEX (vs->v2);
-    GTS_OBJECT (v2)->reserved = GUINT_TO_POINTER (nv++);
-
-    (*GTS_OBJECT (v1)->klass->write) (GTS_OBJECT (v1), fptr);
-    fputc ('\n', fptr);
-
-    (*GTS_OBJECT (v2)->klass->write) (GTS_OBJECT (v2), fptr);
-    fputc ('\n', fptr);
-    
-    while (i--) {
-      CFace * cf = CFACE (scf->f);
-      GtsTriangle ** a, * t;
-
-      fprintf (fptr, "%u %u",
-	       GPOINTER_TO_UINT (g_hash_table_lookup (hash, cf->t)),
-	       cf->flags);
-      if (GTS_OBJECT_CLASS (ps->s->face_class)->write)
-	(*GTS_OBJECT_CLASS (ps->s->face_class)->write) (GTS_OBJECT (cf), fptr);
-      fputc ('\n', fptr);
-
-      a = scf->a1;
-      while ((t = *(a++)))
-	fprintf (fptr, "%u ",
-		 GPOINTER_TO_UINT (g_hash_table_lookup (hash, t)));
-      fprintf (fptr, "\n");
-
-      a = scf->a2;
-      while ((t = *(a++)))
-	fprintf (fptr, "%u ",
-		 GPOINTER_TO_UINT (g_hash_table_lookup (hash, t)));
-      fprintf (fptr, "\n");
-
-      g_hash_table_insert (hash, cf, GUINT_TO_POINTER (nf++));
-
-      scf++;
-    }
-
-    gts_split_expand (vs, ps->s, ps->s->edge_class);
-  }
-
-  gts_surface_foreach_vertex (ps->s, 
-			      (GtsFunc) gts_object_reset_reserved, NULL);
-  g_hash_table_destroy (hash);
-}
-
-static guint surface_read (GtsSurface * surface, 
-			   GtsFile * f,
-			   GPtrArray * vertices,
-			   GPtrArray * faces)
-{
-  GtsEdge ** edges;
-  guint n, nv, ne, nf;
-
-  g_return_val_if_fail (surface != NULL, 1);
-  g_return_val_if_fail (f != NULL, 1);
-  
-  if (f->type != GTS_INT) {
-    gts_file_error (f, "expecting an integer (number of vertices)");
-    return f->line;
-  }
-  nv = atoi (f->token->str);
-
-  gts_file_next_token (f);
-  if (f->type != GTS_INT) {
-    gts_file_error (f, "expecting an integer (number of edges)");
-    return f->line;
-  }
-  ne = atoi (f->token->str);
-
-  gts_file_next_token (f);
-  if (f->type != GTS_INT) {
-    gts_file_error (f, "expecting an integer (number of faces)");
-    return f->line;
-  }
-  nf = atoi (f->token->str);
-
-  gts_file_next_token (f);
-  if (f->type == GTS_STRING) {
-    if (f->type != GTS_STRING) {
-      gts_file_error (f, "expecting a string (GtsSurfaceClass)");
-      return f->line;
-    }
-    gts_file_next_token (f);
-    if (f->type != GTS_STRING) {
-      gts_file_error (f, "expecting a string (GtsFaceClass)");
-      return f->line;
-    }
-    gts_file_next_token (f);
-    if (f->type != GTS_STRING) {
-      gts_file_error (f, "expecting a string (GtsEdgeClass)");
-      return f->line;
-    }
-    gts_file_next_token (f);
-    if (f->type != GTS_STRING) {
-      gts_file_error (f, "expecting a string (GtsVertexClass)");
-      return f->line;
-    }
-    if (!strcmp (f->token->str, "GtsVertexBinary"))
-      GTS_POINT_CLASS (surface->vertex_class)->binary = TRUE;
-    else
-      gts_file_first_token_after (f, '\n');
-  }
-  else
-    gts_file_first_token_after (f, '\n');
-
-  g_ptr_array_set_size (vertices, nv);
-  g_ptr_array_set_size (faces, nf);
-  /* allocate nv + 1 just in case nv == 0 */
-  edges = g_malloc ((ne + 1)*sizeof (GtsEdge *));
-  
-  n = 0;
-  while (n < nv && f->type != GTS_ERROR) {
-    GtsObject * new_vertex =
-      gts_object_new (GTS_OBJECT_CLASS (surface->vertex_class));
-
-    (* GTS_OBJECT_CLASS (surface->vertex_class)->read) (&new_vertex, f);
-    if (f->type != GTS_ERROR) {
-      if (!GTS_POINT_CLASS (surface->vertex_class)->binary)
-	gts_file_first_token_after (f, '\n');
-      g_ptr_array_index (vertices, n++) = new_vertex;
-    }
-    else
-      gts_object_destroy (new_vertex);
-  }
-  if (f->type == GTS_ERROR)
-    nv = n;
-  if (GTS_POINT_CLASS (surface->vertex_class)->binary)
-    gts_file_first_token_after (f, '\n');
-
-  n = 0;
-  while (n < ne && f->type != GTS_ERROR) {
-    guint p1, p2;
-
-    if (f->type != GTS_INT)
-      gts_file_error (f, "expecting an integer (first vertex index)");
-    else {
-      p1 = atoi (f->token->str);
-      if (p1 == 0 || p1 > nv)
-	gts_file_error (f, "vertex index `%d' is out of range `[1,%d]'", 
-			p1, nv);
-      else {
-	gts_file_next_token (f);
-	if (f->type != GTS_INT)
-	  gts_file_error (f, "expecting an integer (second vertex index)");
-	else {
-	  p2 = atoi (f->token->str);
-	  if (p2 == 0 || p2 > nv)
-	    gts_file_error (f, "vertex index `%d' is out of range `[1,%d]'", 
-			    p2, nv);
-	  else {
-	    GtsEdge * new_edge =
-	      gts_edge_new (surface->edge_class,
-			    g_ptr_array_index (vertices, p1 - 1),
-			    g_ptr_array_index (vertices, p2 - 1));
-
-	    gts_file_next_token (f);
-	    if (f->type != '\n')
-	      if (GTS_OBJECT_CLASS (surface->edge_class)->read)
-		(*GTS_OBJECT_CLASS (surface->edge_class)->read)
-		  ((GtsObject **) &new_edge, f);
-	    gts_file_first_token_after (f, '\n');
-	    edges[n++] = new_edge;
-	  }
-	}
-      }
-    }
-  }
-  if (f->type == GTS_ERROR)
-    ne = n;
-
-  n = 0;
-  while (n < nf && f->type != GTS_ERROR) {
-    guint s1, s2, s3;
-
-    if (f->type != GTS_INT)
-      gts_file_error (f, "expecting an integer (first edge index)");
-    else {
-      s1 = atoi (f->token->str);
-      if (s1 == 0 || s1 > ne)
-	gts_file_error (f, "edge index `%d' is out of range `[1,%d]'", 
-			s1, ne);
-      else {
-	gts_file_next_token (f);
-	if (f->type != GTS_INT)
-	  gts_file_error (f, "expecting an integer (second edge index)");
-	else {
-	  s2 = atoi (f->token->str);
-	  if (s2 == 0 || s2 > ne)
-	    gts_file_error (f, "edge index `%d' is out of range `[1,%d]'", 
-			    s2, ne);
-	  else {
-	    gts_file_next_token (f);
-	    if (f->type != GTS_INT)
-	      gts_file_error (f, "expecting an integer (third edge index)");
-	    else {
-	      s3 = atoi (f->token->str);
-	      if (s3 == 0 || s3 > ne)
-		gts_file_error (f, "edge index `%d' is out of range `[1,%d]'", 
-				s3, ne);
-	      else {
-		GtsFace * new_face = gts_face_new (surface->face_class,
-						   edges[s1 - 1],
-						   edges[s2 - 1],
-						   edges[s3 - 1]);
-
-		gts_file_next_token (f);
-		if (f->type != '\n')
-		  if (GTS_OBJECT_CLASS (surface->face_class)->read)
-		    (*GTS_OBJECT_CLASS (surface->face_class)->read)
-		      ((GtsObject **) &new_face, f);
-		gts_file_first_token_after (f, '\n');
-		gts_surface_add_face (surface, new_face);
-		g_ptr_array_index (faces, n++) = new_face;
-	      }
-	    }
-	  }
-	}
-      }
-    }
-  }
-
-  g_free (edges);
-
-  if (f->type == GTS_ERROR) {
-    gts_allow_floating_vertices = TRUE;
-    while (nv)
-      gts_object_destroy (GTS_OBJECT (g_ptr_array_index (vertices, nv-- - 1)));
-    gts_allow_floating_vertices = FALSE;    
-    return f->line;
-  }
-
-  return 0;
-}
-
-/**
- * gts_psurface_open:
- * @klass: a #GtsPSurfaceClass.
- * @s: a #GtsSurface.
- * @split_class: a #GtsSplitClass to use for the #GtsSplit.
- * @f: a #GtsFile.
- *
- * Creates a new #GtsPSurface prepared for input from the file @f 
- * containing a valid GTS representation of a progressive surface. The initial
- * shape of the progressive surface is loaded into @s.
- * 
- * Before being usable as such this progressive surface must be closed using
- * gts_psurface_close(). While open however, the functions
- * gts_psurface_get_vertex_number(), gts_psurface_min_vertex_number() and
- * gts_psurface_max_vertex_number() can still be used.
- *
- * Returns: a new #GtsPSurface or %NULL if there was a format error while
- * reading the file, in which case @f contains information about the error.
- */
-GtsPSurface * gts_psurface_open (GtsPSurfaceClass * klass,
-				 GtsSurface * s,
-				 GtsSplitClass * split_class,
-				 GtsFile * f)
-{
-  GtsPSurface * ps;
-
-  g_return_val_if_fail (klass != NULL, NULL);
-  g_return_val_if_fail (s != NULL, NULL);
-  g_return_val_if_fail (split_class != NULL, NULL);
-  g_return_val_if_fail (f != NULL, NULL);
-
-  ps = GTS_PSURFACE (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  ps->s = s;
-  ps->split_class = split_class;
-
-  ps->vertices = g_ptr_array_new ();
-  ps->faces = g_ptr_array_new ();
-
-  if (surface_read (s, f, ps->vertices, ps->faces)) {
-    ps->s = NULL;
-    gts_object_destroy (GTS_OBJECT (ps));
-    return NULL;
-  }
-
-  ps->min = gts_surface_vertex_number (ps->s);
-  ps->pos = 0;
-
-  if (f->type == GTS_INT) {
-    gint ns = atoi (f->token->str);
-    
-    if (ns > 0) {
-      g_ptr_array_set_size (ps->split, ns);
-      gts_file_first_token_after (f, '\n');
-    }
-  }
-
-  return ps;
-}
-
-/**
- * gts_psurface_read_vertex:
- * @ps: a #GtsPSurface prealably created with gts_psurface_open().
- * @fp: a #GtsFile.
- *
- * Reads in one vertex split operation from @fp and performs the expansion.
- *
- * If an error occurs while reading the file, the @error field of @fp is set.
- *
- * Returns: the newly created #GtsSplit or %NULL if no vertex split could be
- * read from @fp.
- */
-GtsSplit * gts_psurface_read_vertex (GtsPSurface * ps, GtsFile * fp)
-{
-  guint nv, ncf;
-  GtsSplit * vs, * parent;
-  GtsSplitCFace * scf;
-
-  g_return_val_if_fail (ps != NULL, NULL);
-  g_return_val_if_fail (fp != NULL, NULL);
-  g_return_val_if_fail (!GTS_PSURFACE_IS_CLOSED (ps), NULL);
-  
-  if (ps->pos >= ps->split->len)
-    return NULL;
-
-  if (fp->type == GTS_NONE)
-    return NULL;
-  if (fp->type != GTS_INT) {
-    gts_file_error (fp, "expecting an integer (vertex index)");
-    return NULL;
-  }
-  nv = atoi (fp->token->str);
-  if (nv == 0 || nv > ps->vertices->len) {
-    gts_file_error (fp, "vertex index `%d' is out of range `[1,%d]'",
-		    nv, ps->vertices->len);
-    return NULL;
-  }
-
-  gts_file_next_token (fp);
-  if (fp->type != GTS_INT) {
-    gts_file_error (fp, "expecting an integer (ncf)");
-    return NULL;
-  }
-  ncf = atoi (fp->token->str);
-  
-  vs = GTS_SPLIT (gts_object_new (GTS_OBJECT_CLASS (ps->split_class)));
-
-  vs->v = g_ptr_array_index (ps->vertices, nv - 1);
-  vs->v1 = vs->v2 = NULL;
-  vs->cfaces = NULL;
-  vs->ncf = 0;
-
-  gts_file_next_token (fp);
-  if (fp->type != '\n')
-    if (GTS_OBJECT (vs)->klass->read)
-      (* GTS_OBJECT (vs)->klass->read) ((GtsObject **) &vs, fp);
-  gts_file_first_token_after (fp, '\n');
-
-  if (fp->type != GTS_ERROR) {
-    vs->v1 = gts_object_new (GTS_OBJECT_CLASS (ps->s->vertex_class));
-    (* GTS_OBJECT_CLASS (ps->s->vertex_class)->read) (&(vs->v1), fp);
-    if (fp->type != GTS_ERROR) {
-      vs->v1->reserved = vs;
-      g_ptr_array_add (ps->vertices, vs->v1);
-
-      gts_file_first_token_after (fp, '\n');
-      
-      vs->v2 = gts_object_new (GTS_OBJECT_CLASS (ps->s->vertex_class));
-      (*GTS_OBJECT_CLASS (ps->s->vertex_class)->read) (&(vs->v2), fp);
-      if (fp->type != GTS_ERROR) {
-	vs->v2->reserved = vs;
-	g_ptr_array_add (ps->vertices, vs->v2);
-	gts_file_first_token_after (fp, '\n');
-      }
-    }
-  }
-
-  if (fp->type != GTS_ERROR) {
-    scf = vs->cfaces = g_malloc (sizeof (GtsSplitCFace)*ncf);
-    while (fp->type != GTS_ERROR && ncf--) {
-      guint it, flags;
-      GtsFace * f;
-      CFace * cf;
-      GPtrArray * a;
-
-      if (fp->type != GTS_INT)
-	gts_file_error (fp, "expecting an integer (face index)");
-      else {
-	it = atoi (fp->token->str);
-	if (it == 0 || it > ps->faces->len)
-	  gts_file_error (fp, "face index `%d' is out of range `[1,%d]'",
-			  it, ps->faces->len);
-	else {
-	  gts_file_next_token (fp);
-	  if (fp->type != GTS_INT)
-	    gts_file_error (fp, "expecting an integer (flags)");
-	  else {
-	    flags = atoi (fp->token->str);
-	    f = 
-	      GTS_FACE (gts_object_new (GTS_OBJECT_CLASS (ps->s->face_class)));
-
-	    gts_file_next_token (fp);
-	    if (fp->type != '\n')
-	      if (GTS_OBJECT (f)->klass->read)
-		(*GTS_OBJECT (f)->klass->read) ((GtsObject **) &f, fp);
-	    gts_file_first_token_after (fp, '\n');
-	    if (fp->type != GTS_ERROR) {
-	      scf->f = f;
-
-	      cf = (CFace *) f;
-	      GTS_OBJECT (cf)->klass = GTS_OBJECT_CLASS (cface_class ());
-	      cf->parent_split = vs;
-	      cf->t = g_ptr_array_index (ps->faces, it - 1);
-	      cf->flags = flags;
-	  
-	      a = g_ptr_array_new ();
-	      do {
-		if (fp->type != GTS_INT)
-		  gts_file_error (fp, "expecting an integer (face index)");
-		else {
-		  it = atoi (fp->token->str);
-		  if (it > ps->faces->len)
-		    gts_file_error (fp, 
-				    "face index `%d' is out of range `[1,%d]'",
-				    it, ps->faces->len);
-		  else {
-		    g_ptr_array_add (a, g_ptr_array_index (ps->faces, 
-							   it - 1));
-		    gts_file_next_token (fp);
-		  }
-		}
-	      } while (fp->type != GTS_ERROR && fp->type != '\n');
-	      gts_file_first_token_after (fp, '\n');
-	      g_ptr_array_add (a, NULL);
-	      scf->a1 = (GtsTriangle **) a->pdata;
-	      g_ptr_array_free (a, FALSE);
-
-	      if (fp->type != GTS_ERROR) {
-		a = g_ptr_array_new ();
-		do {
-		  if (fp->type != GTS_INT)
-		    gts_file_error (fp, "expecting an integer (face index)");
-		  else {
-		    it = atoi (fp->token->str);
-		    if (it > ps->faces->len)
-		      gts_file_error (fp, 
-				   "face index `%d' is out of range `[1,%d]'",
-				      it, ps->faces->len);
-		    else {
-		      g_ptr_array_add (a, g_ptr_array_index (ps->faces, 
-							     it - 1));
-		      gts_file_next_token (fp);
-		    }
-		  }
-		} while (fp->type != GTS_ERROR && fp->type != '\n');
-		gts_file_first_token_after (fp, '\n');
-		g_ptr_array_add (a, NULL);
-		scf->a2 = (GtsTriangle **) a->pdata;
-		g_ptr_array_free (a, FALSE);
-		
-		g_ptr_array_add (ps->faces, f);
-	      
-		vs->ncf++;
-		scf++;
-	      }
-	    }
-	  }
-	}
-      }
-    }
-  }
-
-  if (fp->type != GTS_ERROR) {
-    if ((parent = GTS_OBJECT (vs->v)->reserved)) {
-      GTS_OBJECT (vs->v)->reserved = NULL;
-      if (parent->v1 == GTS_OBJECT (vs->v))
-	parent->v1 = GTS_OBJECT (vs);
-      else {
-	g_assert (parent->v2 == GTS_OBJECT (vs->v));
-	parent->v2 = GTS_OBJECT (vs);
-      }
-    }
-    g_ptr_array_index (ps->split, ps->pos++) = vs;
-    gts_split_expand (vs, ps->s, ps->s->edge_class);
-
-    return vs;
-  }
-
-  if (vs->v1) gts_object_destroy (vs->v1);
-  if (vs->v2) gts_object_destroy (vs->v2);
-  gts_object_destroy (GTS_OBJECT (vs));
-  
-  return NULL;
-}
-
-/**
- * gts_psurface_close:
- * @ps: a #GtsPSurface prealably created with gts_psurface_open().
- *
- * Closes a progressive surface.
- */
-void gts_psurface_close (GtsPSurface * ps)
-{
-  g_return_if_fail (ps != NULL);
-  g_return_if_fail (!GTS_PSURFACE_IS_CLOSED (ps));
-
-  g_ptr_array_free (ps->vertices, TRUE);
-  g_ptr_array_free (ps->faces, TRUE);
-  ps->faces = ps->vertices = NULL;
-  
-  gts_surface_foreach_vertex (ps->s, 
-			      (GtsFunc) gts_object_reset_reserved, NULL);
-  if (ps->pos > 0)
-    g_ptr_array_set_size (ps->split, ps->pos);
-  if (ps->split->len > 1) {
-    guint i, half = ps->split->len/2, n = ps->split->len - 1;
-    
-    for (i = 0; i < half; i++) {
-      gpointer p1 = g_ptr_array_index (ps->split, i);
-      gpointer p2 = g_ptr_array_index (ps->split, n - i);
-      g_ptr_array_index (ps->split, n - i) = p1;
-      g_ptr_array_index (ps->split, i) = p2;
-    }
-  }
-  ps->pos = 0;
-}
diff --git a/src/gts/stripe.c b/src/gts/stripe.c
deleted file mode 100644
index 7e98a9c..0000000
--- a/src/gts/stripe.c
+++ /dev/null
@@ -1,766 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999-2003  Wagner Toledo Correa, Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include "gts.h"
-
-#define PRINT_HEAP_ELEMENTS 0
-
-typedef struct {
-  GtsTriangle * t;
-  gboolean used;
-  GSList * neighbors;
-  GtsEHeapPair *pos;
-} tri_data_t;
-
-typedef struct {
-  GHashTable * ht;
-} map_t;
-
-typedef struct {
-  map_t * map;
-  GtsEHeap * heap;
-} heap_t;
-
-static tri_data_t    * tri_data_new (GtsTriangle * t);
-static void            tri_data_destroy (tri_data_t * td);
-static guint           tri_data_num_unused_neighbors2 (const tri_data_t * td,
-						       const map_t * map);
-static GHashTable    * tri_data_unused_neighbors2 (const tri_data_t * td,
-						   const map_t * map);
-
-static map_t         * map_new (GtsSurface * s);
-static void            map_destroy (map_t * map);
-static tri_data_t    * map_lookup (const map_t * map, GtsTriangle * t);
-
-
-static heap_t        * heap_new (GtsSurface * s);
-static void            heap_destroy (heap_t * heap);
-static gboolean        heap_is_empty (const heap_t * heap);
-static GtsTriangle   * heap_top (const heap_t * heap);
-static void            heap_remove (heap_t * heap, GtsTriangle * t);
-
-/* helper functions */
-
-static gboolean vertices_are_unique (GtsVertex * v1,
-				     GtsVertex * v2,
-				     GtsVertex * v3)
-{
-  g_assert (v1 && v2 && v3);
-  return (v1 != v2 && v1 != v3 && v2 != v3);
-}
-
-static gboolean vertex_is_one_of (GtsVertex * v,
-				  GtsVertex * v1,
-				  GtsVertex * v2,
-				  GtsVertex * v3)
-{
-  g_assert (v && v1 && v2 && v3);
-  return v == v1 || v == v2 || v == v3;
-}
-
-static guint num_shared_vertices (GtsVertex * u1,
-				  GtsVertex * u2,
-				  GtsVertex * u3,
-				  GtsVertex * v1,
-				  GtsVertex * v2,
-				  GtsVertex * v3)
-{
-  guint n = 0;
-  
-  g_assert (u1 && u2 && u3);
-  g_assert (v1 && v2 && v3);
-  g_assert (vertices_are_unique (u1, u2, u3));
-  g_assert (vertices_are_unique (v1, v2, v3));
-  
-  if (vertex_is_one_of (v1, u1, u2, u3))
-    n++;
-  if (vertex_is_one_of (v2, u1, u2, u3))
-    n++;
-  if (vertex_is_one_of (v3, u1, u2, u3))
-    n++;
-  return n;
-}
-
-static gboolean vertices_match (GtsVertex * v1,
-				GtsVertex * v2,
-				GtsVertex * v3,
-				GtsVertex ** v4,
-				GtsVertex ** v5,
-				GtsVertex ** v6)
-{
-  guint i;
-
-  g_assert (v4 && v5 && v6);
-  g_assert (*v4 && *v5 && *v6);
-  g_assert (vertices_are_unique (*v4, *v5, *v6));
-  
-  for (i = 0; i < 2; i++) {
-    if ((!v1 || (v1 == *v4)) &&
-	(!v2 || (v2 == *v5)) &&
-	(!v3 || (v3 == *v6)))
-      return TRUE;
-    else {
-      GtsVertex * v7 = * v4;
-
-      *v4 = *v5;
-      *v5 = *v6;
-      *v6 = v7;
-    }
-  }
-  return ((!v1 || (v1 == *v4)) &&
-	  (!v2 || (v2 == *v5)) &&
-	  (!v3 || (v3 == *v6)));
-}
-
-static GtsVertex * non_shared_vertex1 (GtsVertex * u1,
-				       GtsVertex * u2,
-				       GtsVertex * u3,
-				       GtsVertex * v1,
-				       GtsVertex * v2,
-				       GtsVertex * v3)
-{
-  GtsVertex * u = NULL;
-
-  g_assert (u1 && u2 && u3);
-  g_assert (v1 && v2 && v3);
-  g_assert (vertices_are_unique (u1, u2, u3));
-  g_assert (vertices_are_unique (v1, v2, v3));
-  g_assert (num_shared_vertices (u1, u2, u3, v1, v2, v3) == 2);
-
-  if (!vertex_is_one_of (u1, v1, v2, v3)) {
-    g_assert (vertex_is_one_of (u2, v1, v2, v3));
-    g_assert (vertex_is_one_of (u3, v1, v2, v3));
-    u = u1;
-  } else if (!vertex_is_one_of (u2, v1, v2, v3)) {
-    g_assert (vertex_is_one_of (u1, v1, v2, v3));
-    g_assert (vertex_is_one_of (u3, v1, v2, v3));
-    u = u2;
-  } else if (!vertex_is_one_of (u3, v1, v2, v3)) {
-    g_assert (vertex_is_one_of (u1, v1, v2, v3));
-    g_assert (vertex_is_one_of (u2, v1, v2, v3));
-    u = u3;
-  } else 
-    g_assert_not_reached ();
-
-  return u;
-}
-
-static void match_vertex (GtsVertex * v,
-			  GtsVertex ** v1,
-			  GtsVertex ** v2,
-			  GtsVertex ** v3)
-{
-  g_assert (v && v1 && v2 && v3);
-  g_assert (*v1 && *v2 && *v3);
-  g_assert (vertex_is_one_of (v, *v1, *v2, *v3));
-  while (*v1 != v) {
-    GtsVertex *v0 = *v1;
-
-    *v1 = *v2;
-    *v2 = *v3;
-    *v3 = v0;
-  }
-}
-
-/* tri_data_t functions */
-
-static tri_data_t * tri_data_new (GtsTriangle * t)
-{
-  tri_data_t * td;
-  
-  td = g_malloc (sizeof (tri_data_t));
-  td->t = t;
-  td->used = FALSE;
-  td->neighbors = gts_triangle_neighbors (t);
-  td->pos = NULL;
-
-  return td;
-}
-
-static void tri_data_destroy (tri_data_t * td)
-{
-  if (!td)
-    return;
-  g_slist_free (td->neighbors);
-  g_free (td);
-}
-
-static guint tri_data_num_unused_neighbors2 (const tri_data_t * td,
-					     const map_t * map)
-{
-  GHashTable *h;
-  guint n;
-
-  g_assert (td);
-  g_assert (map);
-  h = tri_data_unused_neighbors2 (td, map);
-  n = g_hash_table_size (h);
-  g_hash_table_destroy (h);
-  return n;
-}
-
-static void copy_key_to_array (gpointer key,
-			       gpointer value,
-			       gpointer user_data)
-{
-  GtsTriangle * t = key;
-  GtsTriangle *** p = user_data;
-
-  (void) value;
-  g_assert (t);
-  g_assert (p && *p);
-  **p = t;
-  (*p)++;
-}
-
-static gboolean are_neighbors_unique (GHashTable *h)
-{
-  GtsTriangle ** a;
-  GtsTriangle ** p;
-  gint i, j, n;		/* guint won't work if n == 0 */
-
-  g_assert (h);
-  n = g_hash_table_size (h);
-#ifdef DEBUG
-  if (n > 9)
-    g_warning ("triangle has %d 2-level neighbors", n);
-#endif /* DEBUG */
-  a = g_malloc(n*sizeof (GtsTriangle *));
-  p = a;
-  g_hash_table_foreach (h, copy_key_to_array, &p);
-  for (i = 0; i < n - 1; i++) {
-    g_assert (a[i]);
-    for (j = i + 1; j < n; j++) {
-      g_assert (a[j]);
-      if (a[i] == a[j]) {
-	g_free (a);
-	return FALSE;
-      }
-    }
-  }
-  g_free (a);
-  return TRUE;
-}
-
-static GHashTable * tri_data_unused_neighbors2 (const tri_data_t * td,
-						const map_t * map)
-{
-  GHashTable * h = g_hash_table_new (NULL, NULL);
-  GSList * li;
-
-  g_assert (td);
-  g_assert (map);
-  for (li = td->neighbors; li != NULL; li = li->next) {
-    GtsTriangle * t2 = li->data;
-    tri_data_t * td2 = map_lookup (map, t2);
-    GSList * lj;
-
-    g_assert (td2);
-    if (!td2->used) {
-      g_hash_table_insert (h, t2, td2);
-      for (lj = td2->neighbors; lj != NULL; lj = lj->next) {
-	GtsTriangle * t3 = lj->data;
-	tri_data_t * td3 = map_lookup (map, t3);
-
-	g_assert (td3);
-	if (td3 != td && !td3->used)
-	  g_hash_table_insert (h, t3, td3);
-      }
-    }
-  }
-  g_assert (are_neighbors_unique (h));
-  return h;
-}
-
-#if PRINT_HEAP_ELEMENTS
-static void tri_data_print (const tri_data_t * td, FILE * fp)
-{
-  g_assert (td);
-  g_assert (fp);
-  fprintf(fp, "td=%p t=%p used=%d pos=%p key=%f\n",
-	  td, td->t, td->used, td->pos,
-	  td->pos ? td->pos->key : -1.0);
-}
-#endif /* PRINT_HEAP_ELEMENTS */
-
-/* heap_t functions */
-
-static gdouble triangle_priority (gpointer item, gpointer data)
-{
-  GtsTriangle * t = item;
-  map_t * map = data;
-  tri_data_t * td;
-  gdouble k;
-  
-  g_assert (t);
-  g_assert (map);
-  td = map_lookup (map, t);
-  g_assert (td);
-  k = tri_data_num_unused_neighbors2 (td, map);
-  return k;
-}
-
-#if PRINT_HEAP_ELEMENTS
-static void print_heap_element (gpointer data, gpointer user_data)
-{
-  GtsTriangle * t = data;
-  map_t * map = user_data;
-  tri_data_t * td;
-  
-  g_assert (t);
-  g_assert (map);
-  td = map_lookup (map, t);
-  g_assert (td);
-  g_assert (!td->used);
-  g_assert (td->pos);
-  tri_data_print (td, stderr);
-}
-#endif /* PRINT_HEAP_ELEMENTS */
-
-static void insert_entry_into_heap (gpointer key,
-				    gpointer value,
-				    gpointer user_data)
-{
-  GtsTriangle * t = key;
-  tri_data_t * td = value;
-  GtsEHeap * heap = user_data;
-  
-  g_assert (!td->pos);
-  td->pos = gts_eheap_insert (heap, t);
-  g_assert (td->pos);
-}
-
-static heap_t * heap_new (GtsSurface *s)
-{
-  heap_t * heap;
-
-  g_assert (s);
-  heap = g_malloc (sizeof (heap_t));
-  heap->map = map_new (s);
-  heap->heap = gts_eheap_new (triangle_priority, heap->map);
-  g_hash_table_foreach (heap->map->ht,
-			insert_entry_into_heap,
-			heap->heap);
-#if PRINT_HEAP_ELEMENTS
-  gts_eheap_foreach (heap->heap, print_heap_element, heap->map);
-#endif /* PRINT_HEAP_ELEMENTS */
-  return heap;
-}
-
-static void heap_destroy (heap_t * heap)
-{
-  if (!heap)
-    return;
-  map_destroy (heap->map);
-  gts_eheap_destroy (heap->heap);
-  g_free (heap);
-}
-
-static gboolean heap_is_empty (const heap_t * heap)
-{
-  g_assert (heap);
-  g_assert (heap->heap);
-  return gts_eheap_size (heap->heap) == 0;
-}
-
-typedef struct {
-  const heap_t * heap;
-  double min_key;
-} min_key_t;
-
-static GtsTriangle * heap_top (const heap_t * heap)
-{
-  GtsTriangle * t;
-  
-  g_assert (heap);
-  g_assert (heap->heap);
-  t = gts_eheap_top (heap->heap, NULL);
-  return t;
-}
-
-static void decrease_key (gpointer key, gpointer value, gpointer user_data)
-{
-  GtsTriangle * t = key;
-  tri_data_t * td = value;
-  heap_t *heap = user_data;
-  gdouble k;
-  
-  (void) t;
-  g_assert (heap);
-  g_assert (heap->map);
-  g_assert (heap->heap);
-  g_assert (td);
-  g_assert (!td->used);
-  g_assert (td->pos);
-  
-  k = tri_data_num_unused_neighbors2 (td, heap->map);
-  g_assert (k <= td->pos->key);
-#ifdef DEBUG
-  if (k == td->pos->key)
-    g_warning ("same key: %f\n", k);
-#endif /* DEBUG */
-  if (k != td->pos->key) {
-    g_assert (k < td->pos->key);
-    g_assert (k >= 0.0);
-    gts_eheap_decrease_key (heap->heap, td->pos, k);
-  }
-}
-
-static void heap_remove (heap_t * heap, GtsTriangle * t)
-{
-  tri_data_t * td;
-  GHashTable * h;
-  
-  g_assert (heap);
-  g_assert (t);
-  td = map_lookup (heap->map, t);
-  g_assert (td);
-  g_assert (!td->used);
-  g_assert (td->pos);
-  td->used = TRUE;
-  gts_eheap_remove (heap->heap, td->pos);
-  td->pos = NULL;
-  
-  /*	fprintf(stderr, "td: %p\n", td); */
-  h = tri_data_unused_neighbors2 (td, heap->map);
-  g_hash_table_foreach (h, decrease_key, heap);
-  g_hash_table_destroy (h);
-}
-
-/* map_t functions */
-
-static gint create_map_entry (gpointer item, gpointer data)
-{
-  GtsTriangle * t = item;
-  GHashTable * ht = data;
-  tri_data_t * td;
-
-  g_assert (t);
-  g_assert (ht);
-  td = tri_data_new (t);
-  g_hash_table_insert (ht, t, td);
-  return 0;
-}
-
-static void free_map_entry (gpointer key, gpointer value, gpointer user_data)
-{
-  GtsTriangle * t = key;
-  tri_data_t * td = value;
-
-  (void) user_data;
-  g_assert (t);
-  g_assert (td);
-  g_assert (td->t == t);
-  tri_data_destroy (td);
-}
-
-static map_t * map_new (GtsSurface * s)
-{
-  map_t * map;
-
-  map = g_malloc (sizeof (map_t));
-  map->ht = g_hash_table_new (NULL, NULL);
-  gts_surface_foreach_face (s, create_map_entry, map->ht);
-  return map;
-}
-
-static void map_destroy (map_t * map)
-{
-  if (!map)
-    return;
-  g_hash_table_foreach (map->ht, free_map_entry, NULL);
-  g_hash_table_destroy (map->ht);
-  g_free (map);
-}
-
-static tri_data_t * map_lookup (const map_t * map, GtsTriangle * t)
-{
-  tri_data_t * td;
-
-  g_assert (map);
-  g_assert (map->ht);
-  g_assert (t);
-  td = g_hash_table_lookup (map->ht, t);
-  g_assert (td);
-  g_assert (td->t == t);
-  return td;
-}
-
-/* other helper functions */
-
-static GtsTriangle * find_min_neighbor (heap_t * heap, GtsTriangle * t)
-{
-  GtsTriangle * min_neighbor = NULL;
-  gdouble min_key = G_MAXDOUBLE;
-  tri_data_t * td;
-  GSList * li;
-
-  g_assert (heap);
-  g_assert (t);
-
-  td = map_lookup (heap->map, t);
-  for (li = td->neighbors; li != NULL; li = li->next) {
-    GtsTriangle * t2 = li->data;
-    tri_data_t * td2 = map_lookup (heap->map, t2);
-    gdouble k;
-    
-    g_assert (td2);
-    if (td2->used)
-      continue;
-    g_assert (td2->pos);
-    k = td2->pos->key;
-    if (k < min_key) {
-      min_key = k;
-      min_neighbor = t2;
-    }
-  }
-  return min_neighbor;
-}
-
-static GtsTriangle * find_neighbor_forward (heap_t * heap,
-					    GtsTriangle * t,
-					    GtsVertex ** v1,
-					    GtsVertex ** v2,
-					    GtsVertex ** v3,
-					    gboolean left_turn)
-{
-  GtsTriangle * neighbor = NULL;
-  tri_data_t * td;
-  GSList * li;
-
-  g_assert (heap);
-  g_assert (t);
-  g_assert (v1 && v2 && v3);
-  g_assert (vertices_are_unique (*v1, *v2, *v3));
-  
-  td = map_lookup (heap->map, t);
-  g_assert (td);
-  for (li = td->neighbors; li && !neighbor; li = li->next) {
-    GtsTriangle * t2 = li->data;
-    tri_data_t * td2 = map_lookup (heap->map, t2);
-    GtsVertex * v4, * v5, * v6;
-    
-    g_assert (td2);
-    if (t2 == t || td2->used)
-      continue;
-    gts_triangle_vertices (t2, &v4, &v5, &v6);
-    if (left_turn) {
-      if (!vertices_match (*v1, *v3, NULL, &v4, &v5, &v6))
-	continue;
-    } else {
-      if (!vertices_match (*v3, *v2, NULL, &v4, &v5, &v6))
-	continue;
-    }
-    neighbor = t2;
-    *v1 = v4;
-    *v2 = v5;
-    *v3 = v6;
-  }
-  return neighbor;
-}
-
-static GtsTriangle * find_neighbor_backward (heap_t * heap,
-					     GtsTriangle * t,
-					     GtsVertex ** v1,
-					     GtsVertex ** v2,
-					     GtsVertex ** v3,
-					     gboolean left_turn)
-{
-  GtsTriangle * neighbor = NULL;
-  tri_data_t * td;
-  GSList * li;
-
-  g_assert (heap);
-  g_assert (t);
-  g_assert (v1 && v2 && v3);
-  g_assert (vertices_are_unique (*v1, *v2, *v3));
-
-  td = map_lookup (heap->map, t);
-  g_assert (td);
-  for (li = td->neighbors; li && !neighbor; li = li->next) {
-    GtsTriangle * t2 = li->data;
-    tri_data_t * td2 = map_lookup (heap->map, t2);
-    GtsVertex * v4, * v5, * v6;
-    
-    g_assert (td2);
-    if (t2 == t || td2->used)
-      continue;
-    gts_triangle_vertices (t2, &v4, &v5, &v6);
-    if (left_turn) {
-      if (!vertices_match (NULL, *v2, *v1, &v4, &v5, &v6))
-	continue;
-    } else if (!vertices_match(*v1, NULL, *v2, &v4, &v5, &v6))
-      continue;
-    neighbor = t2;
-    *v1 = v4;
-    *v2 = v5;
-    *v3 = v6;
-  }
-  return neighbor;
-}
-
-static GSList * grow_strip_forward (heap_t * heap,
-				    GSList * strip,
-				    GtsTriangle * t,
-				    GtsVertex * v1,
-				    GtsVertex * v2,
-				    GtsVertex * v3)
-{
-  gboolean left_turn;
-  
-  g_assert (heap);
-  g_assert (g_slist_length(strip) == 2);
-  g_assert (t);
-  g_assert (v1 && v2 && v3);
-  g_assert (vertices_are_unique (v1, v2, v3));
-
-  left_turn = TRUE;
-  while ((t = find_neighbor_forward (heap, t, &v1, &v2, &v3, 
-				     left_turn)) != NULL) {
-    heap_remove (heap, t);
-    strip = g_slist_prepend (strip, t);
-    left_turn = !left_turn;
-  }
-  return strip;
-}
-
-static GSList * grow_strip_backward (heap_t * heap,
-				     GSList * strip,
-				     GtsTriangle * t,
-				     GtsVertex * v1,
-				     GtsVertex * v2,
-				     GtsVertex * v3)
-{
-  /* we have to make sure we add an even number of triangles */
-  GtsTriangle * t2;
-
-  g_assert (heap);
-  g_assert (g_slist_length(strip) >= 2);
-  g_assert (t);
-  g_assert (v1 && v2 && v3);
-  g_assert (vertices_are_unique (v1, v2, v3));
-
-  while ((t2 = find_neighbor_backward (heap, t, &v1, &v2, &v3,
-				       FALSE)) != NULL
-	 && (t = find_neighbor_backward (heap, t2, &v1, &v2, &v3,
-					 TRUE)) != NULL) {
-    heap_remove (heap, t2);
-    heap_remove (heap, t);
-    strip = g_slist_prepend (strip, t2);
-    strip = g_slist_prepend (strip, t);
-  }
-  return strip;
-}
-
-static gboolean find_right_turn (GtsVertex ** v1,
-				 GtsVertex ** v2,
-				 GtsVertex ** v3,
-				 GtsVertex ** v4,
-				 GtsVertex ** v5,
-				 GtsVertex ** v6)
-{
-  GtsVertex * v;
-
-  g_assert (v1 && v2 && v3);
-  g_assert (v4 && v5 && v6);
-  g_assert (vertices_are_unique (*v1, *v2, *v3));
-  g_assert (vertices_are_unique (*v4, *v5, *v6));
-  g_assert (num_shared_vertices (*v1, *v2, *v3, *v4, *v5, *v6) == 2);
-
-  v = non_shared_vertex1 (*v1, *v2, *v3, *v4, *v5, *v6);
-  match_vertex (v, v1, v2, v3);
-  match_vertex (*v3, v4, v5, v6);
-
-  g_assert (v1 && v2 && v3);
-  g_assert (v4 && v5 && v6);
-  g_assert (*v4 == *v3);
-
-  if (*v5 == *v2) {
-    g_assert (vertices_are_unique (*v1, *v2, *v3));
-    g_assert (vertices_are_unique (*v4, *v5, *v6));
-    g_assert (num_shared_vertices (*v1, *v2, *v3,
-					*v4, *v5, *v6) == 2);
-    return TRUE;
-  } else {
-#ifdef DEBUG
-    g_warning ("couldn't find a right turn");
-#endif /* DEBUG */
-    return FALSE;
-  }
-}
-
-/**
- * gts_surface_strip:
- * @s: a #GtsSurface.
- *
- * Decompose @s into triangle strips for fast-rendering.
- *
- * Returns: a list of triangle strips containing all the triangles of @s. 
- * A triangle strip is itself a list of successive triangles having one edge
- * in common.
- */
-GSList * gts_surface_strip (GtsSurface *s)
-{
-  GSList * strips = NULL;
-  heap_t * heap;
-
-  g_return_val_if_fail (s != NULL, NULL);
-
-  heap = heap_new (s);
-  while (!heap_is_empty (heap)) {
-    GtsTriangle * t1, * t2;
-    GtsVertex * v1, * v2, * v3, * v4, * v5, * v6;
-    GSList * strip = NULL;
-
-    /* remove heap top */
-    t1 = heap_top (heap);
-    g_assert (t1);
-    heap_remove (heap, t1);
-
-    /* start a new strip */
-    strip = g_slist_prepend (strip, t1);
-
-    /* find second triangle */
-    t2 = find_min_neighbor (heap, t1);
-    if (t2) {
-      g_assert (t2 != t1);
-
-      /* find right turn */
-      gts_triangle_vertices (t1, &v1, &v2, &v3);
-      gts_triangle_vertices (t2, &v4, &v5, &v6);
-      if (find_right_turn (&v1, &v2, &v3, &v4, &v5, &v6)) {
-	heap_remove (heap, t2);
-	strip = g_slist_prepend (strip, t2);
-
-	/* grow strip forward */
-	strip = grow_strip_forward (heap, strip, t2, v4, v5, v6);
-
-	strip = g_slist_reverse (strip);
-
-	/* grow strip backward */
-	strip = grow_strip_backward (heap, strip, t1, v1, v2, v3);
-      }
-    }
-    strips = g_slist_prepend (strips, strip);
-  }
-  strips = g_slist_reverse (strips);
-  heap_destroy (heap);
-
-  return strips;
-}
diff --git a/src/gts/surface.c b/src/gts/surface.c
deleted file mode 100644
index 34c5cbe..0000000
--- a/src/gts/surface.c
+++ /dev/null
@@ -1,2743 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <stdlib.h>
-#include <math.h>
-#include <string.h>
-#include "gts.h"
-
-#include "gts-private.h"
-
-static void destroy_foreach_face (GtsFace * f, GtsSurface * s)
-{
-  f->surfaces = g_slist_remove (f->surfaces, s);
-  if (!GTS_OBJECT_DESTROYED (f) &&
-      !gts_allow_floating_faces && f->surfaces == NULL)
-    gts_object_destroy (GTS_OBJECT (f));
-}
-
-static void surface_destroy (GtsObject * object)
-{
-  GtsSurface * surface = GTS_SURFACE (object);
-  
-  gts_surface_foreach_face (surface, (GtsFunc) destroy_foreach_face, surface);
-#ifdef USE_SURFACE_BTREE
-  g_tree_destroy (surface->faces);
-#else /* not USE_SURFACE_BTREE */
-  g_hash_table_destroy (surface->faces);
-#endif /* not USE_SURFACE_BTREE */
-
-  (* GTS_OBJECT_CLASS (gts_surface_class ())->parent_class->destroy) (object);
-}
-
-static void surface_write (GtsObject * object, FILE * fptr)
-{
-  fprintf (fptr, " %s %s %s %s", 
-	   object->klass->info.name,
-	   GTS_OBJECT_CLASS (GTS_SURFACE (object)->face_class)->info.name,
-	   GTS_OBJECT_CLASS (GTS_SURFACE (object)->edge_class)->info.name,
-	   GTS_POINT_CLASS (GTS_SURFACE (object)->vertex_class)->binary ?
-	   "GtsVertexBinary" :
-	   GTS_OBJECT_CLASS (GTS_SURFACE (object)->vertex_class)->info.name);
-}
-
-static void surface_class_init (GtsSurfaceClass * klass)
-{
-  GTS_OBJECT_CLASS (klass)->destroy = surface_destroy;
-  GTS_OBJECT_CLASS (klass)->write = surface_write;
-  klass->add_face = NULL;
-  klass->remove_face = NULL;
-}
-
-#ifdef USE_SURFACE_BTREE
-static gint compare_pointers (gconstpointer a, gconstpointer b)
-{
-  if (GPOINTER_TO_UINT (a) < GPOINTER_TO_UINT (b))
-    return -1;
-  if (GPOINTER_TO_UINT (a) > GPOINTER_TO_UINT (b))
-    return 1;
-  return 0;
-}
-#endif /* USE_SURFACE_BTREE */
-
-static void surface_init (GtsSurface * surface)
-{
-#ifdef USE_SURFACE_BTREE
-  surface->faces = g_tree_new (compare_pointers);
-#else /* not USE_SURFACE_BTREE */
-  surface->faces = g_hash_table_new (NULL, NULL);
-#endif /* not USE_SURFACE_BTREE */
-  surface->vertex_class = gts_vertex_class ();
-  surface->edge_class = gts_edge_class ();
-  surface->face_class = gts_face_class ();
-  surface->keep_faces = FALSE;
-}
-
-/**
- * gts_surface_class:
- *
- * Returns: the #GtsSurfaceClass.
- */
-GtsSurfaceClass * gts_surface_class (void)
-{
-  static GtsSurfaceClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo surface_info = {
-      "GtsSurface",
-      sizeof (GtsSurface),
-      sizeof (GtsSurfaceClass),
-      (GtsObjectClassInitFunc) surface_class_init,
-      (GtsObjectInitFunc) surface_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (gts_object_class (), &surface_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_surface_new:
- * @klass: a #GtsSurfaceClass.
- * @face_class: a #GtsFaceClass.
- * @edge_class: a #GtsEdgeClass.
- * @vertex_class: a #GtsVertexClass.
- *
- * Returns: a new empty #GtsSurface.
- */
-GtsSurface * gts_surface_new (GtsSurfaceClass * klass,
-			      GtsFaceClass * face_class,
-			      GtsEdgeClass * edge_class,
-			      GtsVertexClass * vertex_class)
-{
-  GtsSurface * s;
-
-  s = GTS_SURFACE (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  s->vertex_class = vertex_class;
-  s->edge_class = edge_class;
-  s->face_class = face_class;
-
-  return s;
-}
-
-/**
- * gts_surface_add_face:
- * @s: a #GtsSurface.
- * @f: a #GtsFace.
- *
- * Adds face @f to surface @s.
- */
-void gts_surface_add_face (GtsSurface * s, GtsFace * f)
-{
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (f != NULL);
-
-  g_assert (s->keep_faces == FALSE);
-
-#ifdef USE_SURFACE_BTREE
-  if (!g_tree_lookup (s->faces, f)) {
-    f->surfaces = g_slist_prepend (f->surfaces, s);
-    g_tree_insert (s->faces, f, f);
-  }
-#else /* not USE_SURFACE_BTREE */
-  if (!g_hash_table_lookup (s->faces, f)) {
-    f->surfaces = g_slist_prepend (f->surfaces, s);
-    g_hash_table_insert (s->faces, f, f);
-  }
-#endif /* not USE_SURFACE_BTREE */
-
-  if (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->add_face)
-    (* GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->add_face) (s, f);
-}
-
-/**
- * gts_surface_remove_face:
- * @s: a #GtsSurface.
- * @f: a #GtsFace.
- *
- * Removes face @f from surface @s.
- */
-void gts_surface_remove_face (GtsSurface * s, 
-			      GtsFace * f)
-{
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (f != NULL);
-
-  g_assert (s->keep_faces == FALSE);
-
-#ifdef USE_SURFACE_BTREE
-  g_tree_remove (s->faces, f);
-#else /* not USE_SURFACE_BTREE */
-  g_hash_table_remove (s->faces, f);
-#endif /* not USE_SURFACE_BTREE */
-
-  f->surfaces = g_slist_remove (f->surfaces, s);
-
-  if (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->remove_face)
-    (* GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->remove_face) (s, f);
-
-  if (!GTS_OBJECT_DESTROYED (f) &&
-      !gts_allow_floating_faces && 
-      f->surfaces == NULL)
-    gts_object_destroy (GTS_OBJECT (f));
-}
-
-/**
- * gts_surface_read:
- * @surface: a #GtsSurface.
- * @f: a #GtsFile.
- *
- * Add to @surface the data read from @f. The format of the file pointed to
- * by @f is as described in gts_surface_write().
- *
- * Returns: 0 if successful or the line number at which the parsing
- * stopped in case of error (in which case the @error field of @f is
- * set to a description of the error which occured).  
- */
-/* Update split.c/surface_read() if modifying this function */
-guint gts_surface_read (GtsSurface * surface, GtsFile * f)
-{
-  GtsVertex ** vertices;
-  GtsEdge ** edges;
-  guint n, nv, ne, nf;
-
-  g_return_val_if_fail (surface != NULL, 1);
-  g_return_val_if_fail (f != NULL, 1);
-
-  if (f->type != GTS_INT) {
-    gts_file_error (f, "expecting an integer (number of vertices)");
-    return f->line;
-  }
-  nv = atoi (f->token->str);
-
-  gts_file_next_token (f);
-  if (f->type != GTS_INT) {
-    gts_file_error (f, "expecting an integer (number of edges)");
-    return f->line;
-  }
-  ne = atoi (f->token->str);
-
-  gts_file_next_token (f);
-  if (f->type != GTS_INT) {
-    gts_file_error (f, "expecting an integer (number of faces)");
-    return f->line;
-  }
-  nf = atoi (f->token->str);
-  
-  gts_file_next_token (f);
-  if (f->type == GTS_STRING) {
-    if (f->type != GTS_STRING) {
-      gts_file_error (f, "expecting a string (GtsSurfaceClass)");
-      return f->line;
-    }
-    gts_file_next_token (f);
-    if (f->type != GTS_STRING) {
-      gts_file_error (f, "expecting a string (GtsFaceClass)");
-      return f->line;
-    }
-    gts_file_next_token (f);
-    if (f->type != GTS_STRING) {
-      gts_file_error (f, "expecting a string (GtsEdgeClass)");
-      return f->line;
-    }
-    gts_file_next_token (f);
-    if (f->type != GTS_STRING) {
-      gts_file_error (f, "expecting a string (GtsVertexClass)");
-      return f->line;
-    }
-    if (!strcmp (f->token->str, "GtsVertexBinary"))
-      GTS_POINT_CLASS (surface->vertex_class)->binary = TRUE;
-    else {
-      GTS_POINT_CLASS (surface->vertex_class)->binary = FALSE;
-      gts_file_first_token_after (f, '\n');
-    }
-  }
-  else
-    gts_file_first_token_after (f, '\n');
-
-  if (nf <= 0)
-    return 0;
-
-  /* allocate nv + 1 just in case nv == 0 */
-  vertices = g_malloc ((nv + 1)*sizeof (GtsVertex *));
-  edges = g_malloc ((ne + 1)*sizeof (GtsEdge *));
-  
-  n = 0;
-  while (n < nv && f->type != GTS_ERROR) {
-    GtsObject * new_vertex =
-      gts_object_new (GTS_OBJECT_CLASS (surface->vertex_class));
-
-    (* GTS_OBJECT_CLASS (surface->vertex_class)->read) (&new_vertex, f);
-    if (f->type != GTS_ERROR) {
-      if (!GTS_POINT_CLASS (surface->vertex_class)->binary)
-	gts_file_first_token_after (f, '\n');
-      vertices[n++] = GTS_VERTEX (new_vertex);
-    }
-    else
-      gts_object_destroy (new_vertex);
-  }
-  if (f->type == GTS_ERROR)
-    nv = n;
-  if (GTS_POINT_CLASS (surface->vertex_class)->binary)
-    gts_file_first_token_after (f, '\n');
-
-  n = 0;
-  while (n < ne && f->type != GTS_ERROR) {
-    guint p1, p2;
-
-    if (f->type != GTS_INT)
-      gts_file_error (f, "expecting an integer (first vertex index)");
-    else {
-      p1 = atoi (f->token->str);
-      if (p1 == 0 || p1 > nv)
-	gts_file_error (f, "vertex index `%d' is out of range `[1,%d]'", 
-			p1, nv);
-      else {
-	gts_file_next_token (f);
-	if (f->type != GTS_INT)
-	  gts_file_error (f, "expecting an integer (second vertex index)");
-	else {
-	  p2 = atoi (f->token->str);
-	  if (p2 == 0 || p2 > nv)
-	    gts_file_error (f, "vertex index `%d' is out of range `[1,%d]'", 
-			    p2, nv);
-	  else {
-	    GtsEdge * new_edge =
-	      gts_edge_new (surface->edge_class,
-			    vertices[p1 - 1], vertices[p2 - 1]);
-
-	    gts_file_next_token (f);
-	    if (f->type != '\n')
-	      if (GTS_OBJECT_CLASS (surface->edge_class)->read)
-		(*GTS_OBJECT_CLASS (surface->edge_class)->read)
-		  ((GtsObject **) &new_edge, f);
-	    gts_file_first_token_after (f, '\n');
-	    edges[n++] = new_edge;
-	  }
-	}
-      }
-    }
-  }
-  if (f->type == GTS_ERROR)
-    ne = n;
-
-  n = 0;
-  while (n < nf && f->type != GTS_ERROR) {
-    guint s1, s2, s3;
-
-    if (f->type != GTS_INT)
-      gts_file_error (f, "expecting an integer (first edge index)");
-    else {
-      s1 = atoi (f->token->str);
-      if (s1 == 0 || s1 > ne)
-	gts_file_error (f, "edge index `%d' is out of range `[1,%d]'", 
-			s1, ne);
-      else {
-	gts_file_next_token (f);
-	if (f->type != GTS_INT)
-	  gts_file_error (f, "expecting an integer (second edge index)");
-	else {
-	  s2 = atoi (f->token->str);
-	  if (s2 == 0 || s2 > ne)
-	    gts_file_error (f, "edge index `%d' is out of range `[1,%d]'", 
-			    s2, ne);
-	  else {
-	    gts_file_next_token (f);
-	    if (f->type != GTS_INT)
-	      gts_file_error (f, "expecting an integer (third edge index)");
-	    else {
-	      s3 = atoi (f->token->str);
-	      if (s3 == 0 || s3 > ne)
-		gts_file_error (f, "edge index `%d' is out of range `[1,%d]'", 
-				s3, ne);
-	      else {
-		GtsFace * new_face = gts_face_new (surface->face_class,
-						   edges[s1 - 1],
-						   edges[s2 - 1],
-						   edges[s3 - 1]);
-
-		gts_file_next_token (f);
-		if (f->type != '\n')
-		  if (GTS_OBJECT_CLASS (surface->face_class)->read)
-		    (*GTS_OBJECT_CLASS (surface->face_class)->read)
-		      ((GtsObject **) &new_face, f);
-		gts_file_first_token_after (f, '\n');
-		gts_surface_add_face (surface, new_face);
-		n++;
-	      }
-	    }
-	  }
-	}
-      }
-    }
-  }
-
-  if (f->type == GTS_ERROR) {
-    gts_allow_floating_vertices = TRUE;
-    while (nv)
-      gts_object_destroy (GTS_OBJECT (vertices[nv-- - 1]));
-    gts_allow_floating_vertices = FALSE;
-  }
-
-  g_free (vertices);
-  g_free (edges);
-
-  if (f->type == GTS_ERROR)
-    return f->line;
-  return 0;
-}
-
-static void sum_area (GtsFace * f, gdouble * area) {
-  *area += gts_triangle_area (GTS_TRIANGLE (f));
-}
-
-/**
- * gts_surface_area:
- * @s: a #GtsSurface.
- *
- * Returns: the area of @s obtained as the sum of the signed areas of its
- * faces.
- */
-gdouble gts_surface_area (GtsSurface * s)
-{  
-  gdouble area = 0.0;
-  gts_surface_foreach_face (s, (GtsFunc)sum_area, &area);
-  return area;
-}
-
-/**
- * gts_range_init:
- * @r: a #GtsRange.
- *
- * Initializes a #GtsRange.
- */
-void gts_range_init (GtsRange * r)
-{
-  g_return_if_fail (r != NULL);
-
-  r->max = - G_MAXDOUBLE;
-  r->min = G_MAXDOUBLE;
-  r->sum = r->sum2 = 0.0;
-  r->n = 0;
-}
-
-/**
- * gts_range_reset:
- * @r: a #GtsRange.
- *
- * Sets all the fields of @r to 0.
- */
-void gts_range_reset (GtsRange * r)
-{
-  g_return_if_fail (r != NULL);
-
-  r->max = 0.0;
-  r->min = 0.0;
-  r->sum = r->sum2 = 0.0;
-  r->n = 0;
-}
-
-/**
- * gts_range_add_value:
- * @r: a #GtsRange.
- * @val: a value to add to @r.
- *
- * Adds @val to @r.
- */
-void gts_range_add_value (GtsRange * r, gdouble val)
-{
-  g_return_if_fail (r != NULL);
-
-  if (val < r->min) r->min = val;
-  if (val > r->max) r->max = val;
-  r->sum += val;
-  r->sum2 += val*val;
-  r->n++;
-}
-
-/**
- * gts_range_update:
- * @r: a #GtsRange.
- * 
- * Updates the fields of @r.
- */
-void gts_range_update (GtsRange * r)
-{
-  g_return_if_fail (r != NULL);
-
-  if (r->n > 0) {
-    if (r->sum2 - r->sum*r->sum/(gdouble) r->n >= 0.)
-      r->stddev = sqrt ((r->sum2 - r->sum*r->sum/(gdouble) r->n)
-			/(gdouble) r->n);
-    else
-      r->stddev = 0.;
-    r->mean = r->sum/(gdouble) r->n;
-  }
-  else 
-    r->min = r->max = r->mean = r->stddev = 0.;
-}
-
-/**
- * gts_range_print:
- * @r: a #GtsRange.
- * @fptr: a file pointer.
- * 
- * Writes a text representation of @r in @fptr.
- */
-void gts_range_print (GtsRange * r, FILE * fptr)
-{
-  g_return_if_fail (r != NULL);
-  g_return_if_fail (fptr != NULL);
-  fprintf (fptr, "min: %g mean: %g | %g max: %g", 
-	   r->min, r->mean, r->stddev, r->max);
-}
-
-static void stats_foreach_vertex (GtsVertex * v, GtsSurfaceStats * stats) 
-{
-  GSList * i = v->segments;
-  guint nedges = 0;
-
-  while (i) {
-    if (GTS_IS_EDGE (i->data) && 
-	gts_edge_has_parent_surface (i->data, stats->parent))
-      nedges++;
-    i = i->next;
-  }
-  gts_range_add_value (&stats->edges_per_vertex, nedges);
-}
-
-static void stats_foreach_edge (GtsEdge * e, GtsSurfaceStats * stats) 
-{
-  guint nt = gts_edge_face_number (e, stats->parent);
-
-  if (gts_segment_is_duplicate (GTS_SEGMENT (e)))
-    stats->n_duplicate_edges++;
-  if (nt == 1)
-    stats->n_boundary_edges++;
-  else if (nt > 2)
-    stats->n_non_manifold_edges++;
-  gts_range_add_value (&stats->faces_per_edge, nt);
-}
-
-static void stats_foreach_face (GtsTriangle * t, GtsSurfaceStats * stats)
-{
-  if (!gts_face_is_compatible (GTS_FACE (t), stats->parent))
-    stats->n_incompatible_faces++;
-  if (gts_triangle_is_duplicate (t))
-    stats->n_duplicate_faces++;
-  stats->n_faces++;
-}
-
-/**
- * gts_surface_stats:
- * @s: a #GtsSurface.
- * @stats: a #GtsSurfaceStats.
- *
- * Fills @stats with the statistics relevant to surface @s.
- */
-void gts_surface_stats (GtsSurface * s, GtsSurfaceStats * stats)
-{
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (stats != NULL);
-
-  stats->parent = s;
-  stats->n_faces = 0;
-  stats->n_incompatible_faces = 0;
-  stats->n_duplicate_faces = 0;
-  stats->n_duplicate_edges = 0;
-  stats->n_boundary_edges = 0;
-  stats->n_non_manifold_edges = 0;
-  gts_range_init (&stats->edges_per_vertex);
-  gts_range_init (&stats->faces_per_edge);
-
-  gts_surface_foreach_vertex (s, (GtsFunc) stats_foreach_vertex, stats);
-  gts_surface_foreach_edge (s, (GtsFunc) stats_foreach_edge, stats);
-  gts_surface_foreach_face (s, (GtsFunc) stats_foreach_face, stats);
-
-  gts_range_update (&stats->edges_per_vertex);
-  gts_range_update (&stats->faces_per_edge);
-}
-
-static void quality_foreach_edge (GtsSegment * s,
-				  GtsSurfaceQualityStats * stats) 
-{
-  GSList * i = GTS_EDGE (s)->triangles;
-
-  gts_range_add_value (&stats->edge_length, 
-		   gts_point_distance (GTS_POINT (s->v1), 
-				       GTS_POINT (s->v2)));
-  while (i) {
-    GSList * j = i->next;
-    while (j) {
-      gts_range_add_value (&stats->edge_angle,
-			   fabs (gts_triangles_angle (i->data, j->data)));
-      j = j->next;
-    }
-    i = i->next;
-  }
-}
-
-static void quality_foreach_face (GtsTriangle * t,
-				  GtsSurfaceQualityStats * stats) 
-{
-  gts_range_add_value (&stats->face_quality, gts_triangle_quality (t));
-  gts_range_add_value (&stats->face_area, gts_triangle_area (t));
-}
-
-/**
- * gts_surface_quality_stats:
- * @s: a #GtsSurface.
- * @stats: a #GtsSurfaceQualityStats.
- *
- * Fills @stats with quality statistics relevant to surface @s.
- */
-void gts_surface_quality_stats (GtsSurface * s, GtsSurfaceQualityStats * stats)
-{
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (stats != NULL);
-
-  stats->parent = s;
-  gts_range_init (&stats->face_quality);
-  gts_range_init (&stats->face_area);
-  gts_range_init (&stats->edge_length);
-  gts_range_init (&stats->edge_angle);
-
-  gts_surface_foreach_edge (s, (GtsFunc) quality_foreach_edge, stats);  
-  gts_surface_foreach_face (s, (GtsFunc) quality_foreach_face, stats);
-
-  gts_range_update (&stats->face_quality);
-  gts_range_update (&stats->face_area);
-  gts_range_update (&stats->edge_length);
-  gts_range_update (&stats->edge_angle);
-}
-
-/**
- * gts_surface_print_stats:
- * @s: a #GtsSurface.
- * @fptr: a file pointer.
- *
- * Writes in the file pointed to by @fptr the statistics for surface @s.
- */
-void gts_surface_print_stats (GtsSurface * s, FILE * fptr)
-{
-  GtsSurfaceStats stats;
-  GtsSurfaceQualityStats qstats;
-
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (fptr != NULL);
-
-  gts_surface_stats (s, &stats);
-  gts_surface_quality_stats (s, &qstats);
-
-  fprintf (fptr, 
-	   "# vertices: %u edges: %u faces: %u\n"
-	   "# Connectivity statistics\n"
-	   "#   incompatible faces: %u\n"
-	   "#   duplicate faces: %u\n"
-	   "#   boundary edges: %u\n"
-	   "#   duplicate edges: %u\n"
-	   "#   non-manifold edges: %u\n",
-	   stats.edges_per_vertex.n, 
-	   stats.faces_per_edge.n,
-	   stats.n_faces,
-	   stats.n_incompatible_faces,
-	   stats.n_duplicate_faces,
-	   stats.n_boundary_edges,
-	   stats.n_duplicate_edges,
-	   stats.n_non_manifold_edges);
-  fputs ("#   edges per vertex: ", fptr); 
-  gts_range_print (&stats.edges_per_vertex, fptr);
-  fputs ("\n#   faces per edge: ", fptr);
-  gts_range_print (&stats.faces_per_edge, fptr);
-  fputs ("\n# Geometric statistics\n#   face quality: ", fptr);
-  gts_range_print (&qstats.face_quality, fptr);
-  fputs ("\n#   face area  : ", fptr);
-  gts_range_print (&qstats.face_area, fptr);
-  fputs ("\n#   edge length : ", fptr);
-  gts_range_print (&qstats.edge_length, fptr);
-  fputc ('\n', fptr);
-}
-
-static void write_vertex (GtsPoint * p, gpointer * data)
-{
-  (*GTS_OBJECT (p)->klass->write) (GTS_OBJECT (p), (FILE *) data[0]);
-  if (!GTS_POINT_CLASS (GTS_OBJECT (p)->klass)->binary)
-    fputc ('\n', (FILE *) data[0]);
-  g_hash_table_insert (data[2], p, 
-		       GUINT_TO_POINTER (++(*((guint *) data[1]))));
-}
-
-static void write_edge (GtsSegment * s, gpointer * data) 
-{
-  fprintf ((FILE *) data[0], "%u %u",
-	   GPOINTER_TO_UINT (g_hash_table_lookup (data[2], s->v1)),
-	   GPOINTER_TO_UINT (g_hash_table_lookup (data[2], s->v2)));
-  if (GTS_OBJECT (s)->klass->write)
-    (*GTS_OBJECT (s)->klass->write) (GTS_OBJECT (s), (FILE *) data[0]);
-  fputc ('\n', (FILE *) data[0]);
-  g_hash_table_insert (data[3], s, 
-		       GUINT_TO_POINTER (++(*((guint *) data[1]))));
-}
-
-static void write_face (GtsTriangle * t, gpointer * data)
-{
-  fprintf (data[0], "%u %u %u",
-	   GPOINTER_TO_UINT (g_hash_table_lookup (data[3], t->e1)),
-	   GPOINTER_TO_UINT (g_hash_table_lookup (data[3], t->e2)),
-	   GPOINTER_TO_UINT (g_hash_table_lookup (data[3], t->e3)));
-  if (GTS_OBJECT (t)->klass->write)
-    (*GTS_OBJECT (t)->klass->write) (GTS_OBJECT (t), data[0]);
-  fputc ('\n', data[0]);
-}
-
-/**
- * gts_surface_write:
- * @s: a #GtsSurface.
- * @fptr: a file pointer.
- * 
- * Writes in the file @fptr an ASCII representation of @s. The file
- * format is as follows. 
- *
- * All the lines beginning with #GTS_COMMENTS are ignored. The first line
- * contains three unsigned integers separated by spaces. The first
- * integer is the number of vertices, nv, the second is the number of
- * edges, ne and the third is the number of faces, nf.
- *
- * Follows nv lines containing the x, y and z coordinates of the
- * vertices.  Follows ne lines containing the two indices (starting
- * from one) of the vertices of each edge. Follows nf lines containing
- * the three ordered indices (also starting from one) of the edges of
- * each face.  
- *
- * The format described above is the least common denominator to all
- * GTS files.  Consistent with an object-oriented approach, the GTS
- * file format is extensible. Each of the lines of the file can be
- * extended with user-specific attributes accessible through the
- * read() and write() virtual methods of each of the objects written
- * (surface, vertices, edges or faces). When read with different
- * object classes, these extra attributes are just ignored.  
- */
-void gts_surface_write (GtsSurface * s, FILE * fptr)
-{
-  guint n;
-  gpointer data[4];
-  GHashTable * vindex, * eindex;
-  GtsSurfaceStats stats;
-
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (fptr != NULL);
-
-  data[0] = fptr;
-  data[1] = &n;
-  data[2] = vindex = g_hash_table_new (NULL, NULL);
-  data[3] = eindex = g_hash_table_new (NULL, NULL);
-
-  gts_surface_stats (s, &stats);
-  fprintf (fptr, "%u %u %u", 
-	   stats.edges_per_vertex.n, 
-	   stats.faces_per_edge.n, 
-	   stats.n_faces);
-  if (GTS_OBJECT (s)->klass->write)
-    (*GTS_OBJECT (s)->klass->write) (GTS_OBJECT (s), fptr);
-  fputc ('\n', fptr);
-  n = 0;
-  gts_surface_foreach_vertex (s, (GtsFunc) write_vertex, data);
-  n = 0;
-  if (GTS_POINT_CLASS (s->vertex_class)->binary)
-    fputc ('\n', fptr);
-  gts_surface_foreach_edge (s, (GtsFunc) write_edge, data);
-  gts_surface_foreach_face (s, (GtsFunc) write_face, data);
-  g_hash_table_destroy (vindex);
-  g_hash_table_destroy (eindex);
-}
-
-static void write_vertex_oogl (GtsPoint * p, gpointer * data)
-{
-  FILE * fp = data[0];
-
-  fprintf (fp, "%g %g %g", p->x, p->y, p->z);
-  if (GTS_OBJECT (p)->klass->color) {
-    GtsColor c = (* GTS_OBJECT (p)->klass->color) (GTS_OBJECT (p));
-    fprintf (fp, " %g %g %g 1.0\n", c.r, c.g, c.b);
-  }
-  else
-    fputc ('\n', fp);
-  GTS_OBJECT (p)->reserved = GUINT_TO_POINTER ((*((guint *) data[1]))++);
-}
-
-static void write_face_oogl (GtsTriangle * t, FILE * fp)
-{
-  GtsVertex * v1, * v2, * v3;
-  gts_triangle_vertices (t, &v1, &v2, &v3);
-  fprintf (fp, "3 %u %u %u",
-	   GPOINTER_TO_UINT (GTS_OBJECT (v1)->reserved),
-	   GPOINTER_TO_UINT (GTS_OBJECT (v2)->reserved),
-	   GPOINTER_TO_UINT (GTS_OBJECT (v3)->reserved));
-  if (GTS_OBJECT (t)->klass->color) {
-    GtsColor c = (* GTS_OBJECT (t)->klass->color) (GTS_OBJECT (t));
-    fprintf (fp, " %g %g %g\n", c.r, c.g, c.b);
-  }
-  else
-    fputc ('\n', fp);
-}
-
-/**
- * gts_surface_write_oogl:
- * @s: a #GtsSurface.
- * @fptr: a file pointer.
- * 
- * Writes in the file @fptr an OOGL (Geomview) representation of @s.
- */
-void gts_surface_write_oogl (GtsSurface * s, FILE * fptr)
-{
-  guint n = 0;
-  gpointer data[2];
-  GtsSurfaceStats stats;
-
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (fptr != NULL);
-
-  data[0] = fptr;
-  data[1] = &n;
-
-  gts_surface_stats (s, &stats);
-  if (GTS_OBJECT_CLASS (s->vertex_class)->color)
-    fputs ("COFF ", fptr);
-  else
-    fputs ("OFF ", fptr);
-  fprintf (fptr, "%u %u %u\n", 
-	   stats.edges_per_vertex.n, 
-	   stats.n_faces,
-	   stats.faces_per_edge.n);
-  gts_surface_foreach_vertex (s, (GtsFunc) write_vertex_oogl, data);
-  gts_surface_foreach_face (s, (GtsFunc) write_face_oogl, fptr);
-  gts_surface_foreach_vertex (s, (GtsFunc) gts_object_reset_reserved, NULL);
-}
-
-static void write_vertex_vtk (GtsPoint * p, gpointer * data)
-{
-  FILE * fp = data[0];
-
-  fprintf (fp, "%g %g %g\n", p->x, p->y, p->z);
-  GTS_OBJECT (p)->reserved = GUINT_TO_POINTER ((*((guint *) data[1]))++);
-}
-
-static void write_face_vtk (GtsTriangle * t, FILE * fp)
-{
-  GtsVertex * v1, * v2, * v3;
-  gts_triangle_vertices (t, &v1, &v2, &v3);
-  fprintf (fp, "3 %u %u %u\n",
-	   GPOINTER_TO_UINT (GTS_OBJECT (v1)->reserved),
-	   GPOINTER_TO_UINT (GTS_OBJECT (v2)->reserved),
-	   GPOINTER_TO_UINT (GTS_OBJECT (v3)->reserved));
-}
-
-/**
- * gts_surface_write_vtk:
- * @s: a #GtsSurface.
- * @fptr: a file pointer.
- * 
- * Writes in the file @fptr a VTK representation of @s.
- */
-void gts_surface_write_vtk (GtsSurface * s, FILE * fptr)
-{
-  guint n = 0;
-  gpointer data[2];
-  GtsSurfaceStats stats;
-
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (fptr != NULL);
-
-  data[0] = fptr;
-  data[1] = &n;
-
-  gts_surface_stats (s, &stats);
-  fprintf (fptr,
-	   "# vtk DataFile Version 2.0\n"
-	   "Generated by GTS\n"
-           "ASCII\n"
-	   "DATASET POLYDATA\n"
-	   "POINTS %u float\n",
-	   stats.edges_per_vertex.n);
-  gts_surface_foreach_vertex (s, (GtsFunc) write_vertex_vtk, data);
-  fprintf (fptr,
-	   "POLYGONS %u %u\n",
-	   stats.n_faces, stats.n_faces*4);
-  gts_surface_foreach_face (s, (GtsFunc) write_face_vtk, fptr);
-  gts_surface_foreach_vertex (s, (GtsFunc) gts_object_reset_reserved, NULL);  
-}
-
-static void write_edge_oogl_boundary (GtsSegment * s, gpointer * data)
-{
-  if (!gts_edge_is_boundary (GTS_EDGE (s), data[1]))
-    return;
-
-  if (GTS_OBJECT (s)->klass->color) {
-    GtsColor c = (* GTS_OBJECT (s)->klass->color) (GTS_OBJECT (s));
-    fprintf (data[0], "VECT 1 2 1 2 1 %g %g %g %g %g %g %g %g %g 1.\n",
-	     GTS_POINT (s->v1)->x, GTS_POINT (s->v1)->y, GTS_POINT (s->v1)->z,
-	     GTS_POINT (s->v2)->x, GTS_POINT (s->v2)->y, GTS_POINT (s->v2)->z,
-	     c.r, c.g, c.b);
-  }
-  else
-    fprintf (data[0], "VECT 1 2 0 2 0 %g %g %g %g %g %g\n",
-	     GTS_POINT (s->v1)->x, GTS_POINT (s->v1)->y, GTS_POINT (s->v1)->z,
-	     GTS_POINT (s->v2)->x, GTS_POINT (s->v2)->y, GTS_POINT (s->v2)->z);
-}
-
-/**
- * gts_surface_write_oogl_boundary:
- * @s: a #GtsSurface.
- * @fptr: a file pointer.
- * 
- * Writes in the file @fptr an OOGL (Geomview) representation of the
- * boundary of @s.  
- */
-void gts_surface_write_oogl_boundary (GtsSurface * s, FILE * fptr)
-{
-  gpointer data[2];
-
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (fptr != NULL);
-
-  data[0] = fptr;
-  data[1] = s;
-  fputs ("LIST {\n", fptr);
-  gts_surface_foreach_edge (s, (GtsFunc) write_edge_oogl_boundary, data);
-  fputs ("}\n", fptr);
-}
-
-#ifdef USE_SURFACE_BTREE
-static gint vertex_foreach_face (GtsTriangle * t,
-				 gpointer t_data,
-				 gpointer * info)
-#else /* not USE_SURFACE_BTREE */
-static void vertex_foreach_face (GtsTriangle * t,
-				 gpointer t_data,
-				 gpointer * info)
-#endif /* not USE_SURFACE_BTREE */
-{
-  GHashTable * hash = info[0];
-  gpointer data = info[1];
-  GtsFunc func = (GtsFunc) info[2];
-  GtsSegment 
-    * s1 = GTS_SEGMENT (t->e1);
-
-  if (!g_hash_table_lookup (hash, s1->v1)) {
-    (*func) (s1->v1, data);
-    g_hash_table_insert (hash, s1->v1, GINT_TO_POINTER (-1));
-  }
-  if (!g_hash_table_lookup (hash, s1->v2)) {
-    (*func) (s1->v2, data);
-    g_hash_table_insert (hash, s1->v2, GINT_TO_POINTER (-1));
-  }
-  if (!g_hash_table_lookup (hash, gts_triangle_vertex (t))) {
-    (*func) (gts_triangle_vertex (t), data);
-    g_hash_table_insert (hash, gts_triangle_vertex (t), 
-			 GINT_TO_POINTER (-1));
-  }
-#ifdef USE_SURFACE_BTREE
-  return FALSE;
-#endif /* USE_SURFACE_BTREE */
-}
-
-/**
- * gts_surface_foreach_vertex:
- * @s: a #GtsSurface.
- * @func: a #GtsFunc.
- * @data: user data to be passed to @func.
- *
- * Calls @func once for each vertex of @s.
- */
-void gts_surface_foreach_vertex (GtsSurface * s, GtsFunc func, gpointer data)
-{
-  gpointer info[3];
-
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (func != NULL);
-
-  /* forbid removal of faces */
-  s->keep_faces = TRUE;
-  info[0] = g_hash_table_new (NULL, NULL);
-  info[1] = data;
-  info[2] = func;
-#ifdef USE_SURFACE_BTREE
-  g_tree_traverse (s->faces, (GTraverseFunc) vertex_foreach_face, G_IN_ORDER,
-		   info);
-#else /* not USE_SURFACE_BTREE */
-  g_hash_table_foreach (s->faces, (GHFunc) vertex_foreach_face, info);
-#endif /* not USE_SURFACE_BTREE */
-  g_hash_table_destroy (info[0]);
-  /* allow removal of faces */
-  s->keep_faces = FALSE;
-}
-
-#ifdef USE_SURFACE_BTREE
-static gint edge_foreach_face (GtsTriangle * t,
-			       gpointer t_data, 
-			       gpointer * info)
-#else /* not USE_SURFACE_BTREE */
-static void edge_foreach_face (GtsTriangle * t,
-			       gpointer t_data, 
-			       gpointer * info)
-#endif /* not USE_SURFACE_BTREE */
-{
-  GHashTable * hash = info[0];
-  gpointer data = info[1];
-  GtsFunc func = (GtsFunc) info[2];
-
-  if (!g_hash_table_lookup (hash, t->e1)) {
-    (*func) (t->e1, data);
-    g_hash_table_insert (hash, t->e1, GINT_TO_POINTER (-1));
-  }
-  if (!g_hash_table_lookup (hash, t->e2)) {
-    (*func) (t->e2, data);
-    g_hash_table_insert (hash, t->e2, GINT_TO_POINTER (-1));
-  }
-  if (!g_hash_table_lookup (hash, t->e3)) {
-    (*func) (t->e3, data);
-    g_hash_table_insert (hash, t->e3, GINT_TO_POINTER (-1));
-  }
-#ifdef USE_SURFACE_BTREE
-  return FALSE;
-#endif /* not USE_SURFACE_BTREE */
-}
-
-/**
- * gts_surface_foreach_edge:
- * @s: a #GtsSurface.
- * @func: a #GtsFunc.
- * @data: user data to be passed to @func.
- *
- * Calls @func once for each edge of @s.
- */
-void gts_surface_foreach_edge (GtsSurface * s, GtsFunc func, gpointer data)
-{
-  gpointer info[3];
-
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (func != NULL);
-  
-  /* forbid removal of faces */
-  s->keep_faces = TRUE;
-  info[0] = g_hash_table_new (NULL, NULL);
-  info[1] = data;
-  info[2] = func;
-#ifdef USE_SURFACE_BTREE
-  g_tree_traverse (s->faces, (GTraverseFunc) edge_foreach_face, G_IN_ORDER,
-		   info);
-#else /* not USE_SURFACE_BTREE */
-  g_hash_table_foreach (s->faces, (GHFunc) edge_foreach_face, info);
-#endif /* not USE_SURFACE_BTREE */
-  g_hash_table_destroy (info[0]);
-  /* allow removal of faces */
-  s->keep_faces = FALSE;
-}
-
-#ifdef USE_SURFACE_BTREE
-static gint foreach_face (GtsFace * f, 
-			  gpointer t_data,
-			  gpointer * info)
-#else /* not USE_SURFACE_BTREE */
-static void foreach_face (GtsFace * f, 
-			  gpointer t_data,
-			  gpointer * info)
-#endif /* not USE_SURFACE_BTREE */
-{
-  (*((GtsFunc) info[0])) (f, info[1]);
-#ifdef USE_SURFACE_BTREE
-  return FALSE;
-#endif /* USE_SURFACE_BTREE */
-}
-
-/**
- * gts_surface_foreach_face:
- * @s: a #GtsSurface.
- * @func: a #GtsFunc.
- * @data: user data to be passed to @func.
- *
- * Calls @func once for each face of @s.
- */
-void gts_surface_foreach_face (GtsSurface * s,
-			       GtsFunc func, 
-			       gpointer data)
-{
-  gpointer info[2];
-
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (func != NULL);
-
-  /* forbid removal of faces */
-  s->keep_faces = TRUE;
-  info[0] = func;
-  info[1] = data;
-#ifdef USE_SURFACE_BTREE
-  g_tree_traverse (s->faces, (GTraverseFunc) foreach_face, G_IN_ORDER,
-		   info);
-#else /* not USE_SURFACE_BTREE */
-  g_hash_table_foreach (s->faces, (GHFunc) foreach_face, info);
-#endif /* not USE_SURFACE_BTREE */
-  /* allow removal of faces */
-  s->keep_faces = FALSE;
-}
-
-#ifdef USE_SURFACE_BTREE
-static gint foreach_face_remove (GtsFace * f,
-				 gpointer t_data,
-				 gpointer * info)
-{
-  if ((*((GtsFunc) info[0])) (f, info[1])) {
-    GtsSurface * s = info[2];
-    guint * n = info[3];
-
-    f->surfaces = g_slist_remove (f->surfaces, s);
-    if (!GTS_OBJECT_DESTROYED (f) &&
-	!gts_allow_floating_faces && 
-	f->surfaces == NULL)
-      gts_object_destroy (GTS_OBJECT (f));
-    
-    if (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->remove_face)
-      (* GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->remove_face) (s, f);
-
-    g_tree_remove (s->faces, f);
-    (*n)++;
-  }
-  return FALSE;
-}
-#else /* not USE_SURFACE_BTREE */
-static gboolean foreach_face_remove (GtsFace * f,
-				     gpointer t_data,
-				     gpointer * info)
-{
-  if ((*((GtsFunc) info[0])) (f, info[1])) {
-    GtsSurface * s = info[2];
-
-    f->surfaces = g_slist_remove (f->surfaces, s);
-    if (!GTS_OBJECT_DESTROYED (f) &&
-	!gts_allow_floating_faces && 
-	f->surfaces == NULL)
-      gts_object_destroy (GTS_OBJECT (f));
-    
-    if (GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->remove_face)
-      (* GTS_SURFACE_CLASS (GTS_OBJECT (s)->klass)->remove_face) (s, f);
-
-    return TRUE;
-  }
-  return FALSE;
-}
-#endif /* not USE_SURFACE_BTREE */
-
-/**
- * gts_surface_foreach_face_remove:
- * @s: a #GtsSurface.
- * @func: a #GtsFunc.
- * @data: user data to be passed to @func.
- *
- * Calls @func once for each face of @s. If @func returns %TRUE the
- * corresponding face is removed from @s (and destroyed if it does not
- * belong to any other surface and #gts_allow_floating_faces is set to
- * %FALSE).
- *
- * Returns: the number of faces removed from @s.  
- */
-guint gts_surface_foreach_face_remove (GtsSurface * s,
-				       GtsFunc func, 
-				       gpointer data)
-{
-  gpointer info[4];
-  guint n = 0;
-
-  g_return_val_if_fail (s != NULL, 0);
-  g_return_val_if_fail (func != NULL, 0);
-
-  /* forbid removal of faces */
-  s->keep_faces = TRUE;
-  info[0] = func;
-  info[1] = data;
-  info[2] = s;
-#ifdef USE_SURFACE_BTREE
-  info[3] = &n;
-  g_tree_traverse (s->faces, (GTraverseFunc) foreach_face_remove, G_PRE_ORDER,
-		   info);
-#else /* not USE_SURFACE_BTREE */
-  n = g_hash_table_foreach_remove (s->faces, 
-				   (GHRFunc) foreach_face_remove, 
-				   info);
-#endif /* not USE_SURFACE_BTREE */
-  /* allow removal of faces */
-  s->keep_faces = FALSE;
-  
-  return n;
-}
-
-static void midvertex_insertion (GtsEdge * e,
-				 GtsSurface * surface,
-				 GtsEHeap * heap,
-				 GtsRefineFunc refine_func,
-				 gpointer refine_data,
-				 GtsVertexClass * vertex_class,
-				 GtsEdgeClass * edge_class)
-{
-  GtsVertex * midvertex;
-  GtsEdge * e1, * e2;
-  GSList * i;
-
-  midvertex = (*refine_func) (e, vertex_class, refine_data);
-  e1 = gts_edge_new (edge_class, GTS_SEGMENT (e)->v1, midvertex);
-  gts_eheap_insert (heap, e1);
-  e2 = gts_edge_new (edge_class, GTS_SEGMENT (e)->v2, midvertex);
-  gts_eheap_insert (heap, e2);
-  
-  /* creates new faces and modifies old ones */
-  i = e->triangles;
-  while (i) {
-    GtsTriangle * t = i->data;
-    GtsVertex * v1, * v2, * v3;
-    GtsEdge * te2, * te3, * ne, * tmp;
-
-    gts_triangle_vertices_edges (t, e, &v1, &v2, &v3, &e, &te2, &te3);
-    ne = gts_edge_new (edge_class, midvertex, v3);
-    gts_eheap_insert (heap, ne);
-    if (GTS_SEGMENT (e1)->v1 == v2) {
-      tmp = e1; e1 = e2; e2 = tmp;
-    }
-    e1->triangles = g_slist_prepend (e1->triangles, t);
-    ne->triangles = g_slist_prepend (ne->triangles, t);
-    te2->triangles = g_slist_remove (te2->triangles, t);
-    t->e1 = e1; t->e2 = ne; t->e3 = te3;
-    gts_surface_add_face (surface, 
-			  gts_face_new (surface->face_class, e2, te2, ne));
-    i = i->next;
-  }
-  /* destroys edge */
-  g_slist_free (e->triangles);
-  e->triangles = NULL;
-  gts_object_destroy (GTS_OBJECT (e));
-}
-
-static gdouble edge_length2_inverse (GtsSegment * s)
-{
-  return - gts_point_distance2 (GTS_POINT (s->v1), GTS_POINT (s->v2));
-}
-
-static void create_heap_refine (GtsEdge * e, GtsEHeap * heap)
-{
-  gts_eheap_insert (heap, e);
-}
-
-/**
- * gts_surface_refine:
- * @surface: a #GtsSurface.
- * @cost_func: a function returning the cost for a given edge.
- * @cost_data: user data to be passed to @cost_func.
- * @refine_func: a #GtsRefineFunc.
- * @refine_data: user data to be passed to @refine_func.
- * @stop_func: a #GtsStopFunc.
- * @stop_data: user data to be passed to @stop_func.
- *
- * Refine @surface using a midvertex insertion technique. All the
- * edges of @surface are ordered according to @cost_func. The edges
- * are then processed in order until @stop_func returns %TRUE. Each
- * edge is split in two and new edges and faces are created.
- *
- * If @cost_func is set to %NULL, the edges are sorted according 
- * to their length squared (the longest is on top).
- *
- * If @refine_func is set to %NULL gts_segment_midvertex() is used.
- * 
- */
-void gts_surface_refine (GtsSurface * surface,
-			 GtsKeyFunc cost_func,
-			 gpointer cost_data,
-			 GtsRefineFunc refine_func,
-			 gpointer refine_data,
-			 GtsStopFunc stop_func,
-			 gpointer stop_data)
-{
-  GtsEHeap * heap;
-  GtsEdge * e;
-  gdouble top_cost;
-
-  g_return_if_fail (surface != NULL);
-  g_return_if_fail (stop_func != NULL);
-
-  if (cost_func == NULL)
-    cost_func = (GtsKeyFunc) edge_length2_inverse;
-  if (refine_func == NULL)
-    refine_func = (GtsRefineFunc) gts_segment_midvertex;
-
-  heap = gts_eheap_new (cost_func, cost_data);
-  gts_eheap_freeze (heap);
-  gts_surface_foreach_edge (surface, (GtsFunc) create_heap_refine, heap);
-  gts_eheap_thaw (heap);
-  while ((e = gts_eheap_remove_top (heap, &top_cost)) &&
-	 !(*stop_func) (top_cost,
-			gts_eheap_size (heap) + 
-			gts_edge_face_number (e, surface) + 2,
-			stop_data))
-    midvertex_insertion (e, surface, heap, refine_func, refine_data,
-			 surface->vertex_class, surface->edge_class);
-  gts_eheap_destroy (heap);
-}
-
-static GSList * edge_triangles (GtsEdge * e1, GtsEdge * e)
-{
-  GSList * i = e1->triangles;
-  GSList * triangles = NULL;
-  
-  while (i) {
-    GtsTriangle * t = i->data;
-    if (t->e1 == e || t->e2 == e || t->e3 == e) {
-      GtsEdge * e2;
-      GSList * j;
-      if (t->e1 == e) {
-	if (t->e2 == e1)
-	  e2 = t->e3;
-	else
-	  e2 = t->e2;
-      }
-      else if (t->e2 == e) {
-	if (t->e3 == e1)
-	  e2 = t->e1;
-	else
-	  e2 = t->e3;
-      }
-      else {
-	if (t->e2 == e1)
-	  e2 = t->e1;
-	else
-	  e2 = t->e2;
-      }
-      j = e2->triangles;
-      while (j) {
-	GtsTriangle * t = j->data;
-	if (t->e1 != e && t->e2 != e && t->e3 != e)
-	  triangles = g_slist_prepend (triangles, t);
-	j = j->next;
-      }
-    }
-    else
-      triangles = g_slist_prepend (triangles, t);
-    i = i->next;
-  }
-  return triangles;
-}
-
-static void replace_vertex (GSList * i, GtsVertex * v1, GtsVertex * v)
-{
-  while (i) {
-    GtsSegment * s = i->data;
-    if (s->v1 == v1)
-      s->v1 = v;
-    else
-      s->v2 = v;
-    i = i->next;
-  }
-}
-
-/**
- * gts_edge_collapse_creates_fold:
- * @e: a #GtsEdge.
- * @v: a #GtsVertex.
- * @max:  the maximum value of the square of the cosine of the angle between
- * two triangles.
- *
- * Returns: %TRUE if collapsing edge @e to vertex @v would create
- * faces making an angle the cosine squared of which would be larger than max,
- * %FALSE otherwise.  
- */
-gboolean gts_edge_collapse_creates_fold (GtsEdge * e, 
-					 GtsVertex * v,
-					 gdouble max)
-{
-  GtsVertex * v1, * v2;
-  GtsSegment * s;
-  GSList * i;
-  gboolean folded = FALSE;
-
-  g_return_val_if_fail (e != NULL, TRUE);
-  g_return_val_if_fail (v != NULL, TRUE);
-
-  s = GTS_SEGMENT (e);
-  v1 = s->v1;
-  v2 = s->v2;
-  replace_vertex (v1->segments, v1, v);
-  replace_vertex (v2->segments, v2, v);
-
-  i = v1->segments;
-  while (i && !folded) {
-    GtsSegment * s = i->data;
-    if (GTS_IS_EDGE (s)) {
-      GtsEdge * e1 = GTS_EDGE (s);
-      if (e1 != e) {
-	GSList * triangles = edge_triangles (e1, e);
-	folded = gts_triangles_are_folded (triangles, s->v1, s->v2, max);
-	g_slist_free (triangles);
-      }
-    }
-    i = i->next;
-  }
-
-  i = v2->segments;
-  while (i && !folded) {
-    GtsSegment * s = i->data;
-    if (GTS_IS_EDGE (s)) {
-      GtsEdge * e1 = GTS_EDGE (s);
-      if (e1 != e) {
-	GSList * triangles = edge_triangles (e1, e);
-	folded = gts_triangles_are_folded (triangles, s->v1, s->v2, max);
-	g_slist_free (triangles);
-      }
-    }
-    i = i->next;
-  }
-#if 1
-  if (!folded) {
-    GSList * triangles = gts_vertex_triangles (v1, NULL);
-    i = triangles = gts_vertex_triangles (v2, triangles);
-    while (i && !folded) {
-      GtsTriangle * t = i->data;
-      if (t->e1 != e && t->e2 != e && t->e3 != e) {
-	GtsEdge * e1 = gts_triangle_edge_opposite (t, v);
-	g_assert (e1);
-	folded = gts_triangles_are_folded (e1->triangles, 
-					   GTS_SEGMENT (e1)->v1,
-					   GTS_SEGMENT (e1)->v2,
-					   max);
-      }
-      i = i->next;
-    }
-    g_slist_free (triangles);
-  }
-#endif
-  replace_vertex (v1->segments, v, v1);
-  replace_vertex (v2->segments, v, v2);
-  return folded;
-}
-
-/**
- * gts_edge_collapse_is_valid:
- * @e: a #GtsEdge.
- *
- * An implementation of the topological constraints described in the 
- * "Mesh Optimization" article of Hoppe et al (1993).
- *
- * Returns: %TRUE if @e can be collapsed without violation of the topological
- * constraints, %FALSE otherwise.
- */
-gboolean gts_edge_collapse_is_valid (GtsEdge * e)
-{
-  GSList * i;
-
-  g_return_val_if_fail (e != NULL, FALSE);
-
-  i = GTS_SEGMENT (e)->v1->segments;
-  while (i) {
-    GtsEdge * e1 = i->data;
-    if (e1 != e && GTS_IS_EDGE (e1)) {
-      GtsEdge * e2 = NULL;
-      GSList * j = GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e)->v1 ? 
-	GTS_SEGMENT (e1)->v2->segments : GTS_SEGMENT (e1)->v1->segments;
-      while (j && !e2) {
-	GtsEdge * e1 = j->data;
-	if (GTS_IS_EDGE (e1) && 
-	    (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e)->v2 || 
-	     GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e)->v2))
-	  e2 = e1;
-	j = j->next;
-      }
-      if (e2 && !gts_triangle_use_edges (e, e1, e2))
-	return FALSE;
-    }
-    i = i->next;
-  }
-
-  if (gts_edge_is_boundary (e, NULL)) {
-    GtsTriangle * t = e->triangles->data;
-    if (gts_edge_is_boundary (t->e1, NULL) &&
-	gts_edge_is_boundary (t->e2, NULL) &&
-	gts_edge_is_boundary (t->e3, NULL))
-      return FALSE;
-  }
-  else {
-    if (gts_vertex_is_boundary (GTS_SEGMENT (e)->v1, NULL) &&
-	gts_vertex_is_boundary (GTS_SEGMENT (e)->v2, NULL))
-      return FALSE;    
-    if (gts_edge_belongs_to_tetrahedron (e))
-      return FALSE;
-  }
-
-  return TRUE;
-}
-
-#define HEAP_INSERT_EDGE(h, e) (GTS_OBJECT (e)->reserved = gts_eheap_insert (h, e))
-#define HEAP_REMOVE_EDGE(h, e) (gts_eheap_remove (h, GTS_OBJECT (e)->reserved),\
-                                GTS_OBJECT (e)->reserved = NULL)
-
-static GtsVertex * edge_collapse (GtsEdge * e,
-				  GtsEHeap * heap,
-				  GtsCoarsenFunc coarsen_func,
-				  gpointer coarsen_data,
-				  GtsVertexClass * klass,
-				  gdouble maxcosine2)
-{
-  GSList * i;
-  GtsVertex  * v1 = GTS_SEGMENT (e)->v1, * v2 = GTS_SEGMENT (e)->v2, * mid;
-
-  /* if the edge is degenerate (i.e. v1 == v2), destroy and return */
-  if (v1 == v2) {
-    gts_object_destroy (GTS_OBJECT (e));
-    return NULL;
-  }
-
-  if (!gts_edge_collapse_is_valid (e)) {
-    GTS_OBJECT (e)->reserved = 
-      gts_eheap_insert_with_key (heap, e, G_MAXDOUBLE);
-    return NULL;
-  }
-
-  mid = (*coarsen_func) (e, klass, coarsen_data);
-
-  if (gts_edge_collapse_creates_fold (e, mid, maxcosine2)) {
-    GTS_OBJECT (e)->reserved = 
-      gts_eheap_insert_with_key (heap, e, G_MAXDOUBLE);
-    gts_object_destroy (GTS_OBJECT (mid));
-    return NULL;
-  }
-
-  gts_object_destroy (GTS_OBJECT (e));
-
-  gts_vertex_replace (v1, mid);
-  gts_object_destroy (GTS_OBJECT (v1));
-  gts_vertex_replace (v2, mid);
-  gts_object_destroy (GTS_OBJECT (v2));
-
-  /* destroy duplicate edges */
-  i = mid->segments;
-  while (i) {
-    GtsEdge * e1 = i->data;
-    GtsEdge * duplicate;
-    while ((duplicate = gts_edge_is_duplicate (e1))) {
-      gts_edge_replace (duplicate, GTS_EDGE (e1));
-      HEAP_REMOVE_EDGE (heap, duplicate);
-      gts_object_destroy (GTS_OBJECT (duplicate));
-    }
-    i = i->next;
-    if (!e1->triangles) {
-      /* e1 is the result of the collapse of one edge of a pair of identical
-	 faces (it should not happen unless duplicate triangles are present in
-	 the initial surface) */
-      g_warning ("file %s: line %d (%s): probably duplicate triangle.",
-		 __FILE__, __LINE__, G_GNUC_PRETTY_FUNCTION);
-      HEAP_REMOVE_EDGE (heap, e1);
-      gts_object_destroy (GTS_OBJECT (e1));
-      if (i == NULL) /* mid has been destroyed */
-	mid = NULL;
-    }
-  }
-
-  return mid;
-}
-
-/*
- * I don't see where this code is ever used, but keep it for a bit 
- * in case it is needed for debugging
- */
-#ifdef GTS_NEED_UPDATE_CLOSEST_NEIGHBORS
-static void update_closest_neighbors (GtsVertex * v, GtsEHeap * heap)
-{
-  GSList * i = v->segments;
-  
-  while (i) {
-    GtsSegment * s = i->data;
-    if (GTS_IS_EDGE (s)) {
-      HEAP_REMOVE_EDGE (heap, GTS_EDGE (s));
-      HEAP_INSERT_EDGE (heap, GTS_EDGE (s));
-    }
-    i = i->next;
-  }
-}
-#endif
-
-static void update_2nd_closest_neighbors (GtsVertex * v, GtsEHeap * heap)
-{
-  GSList * i = v->segments;
-  GSList * list = NULL;
-  
-  while (i) {
-    GtsSegment * s = i->data;
-    if (GTS_IS_EDGE (s)) {
-      GtsVertex * v1 = s->v1 == v ? s->v2 : s->v1;
-      GSList * j = v1->segments;
-      while (j) {
-	GtsSegment * s1 = j->data;
-	if (GTS_IS_EDGE (s1) && !g_slist_find (list, s1))
-	  list = g_slist_prepend (list, s1);
-	j = j->next;
-      }
-    }
-    i = i->next;
-  }
-
-  i = list;
-  while (i) {
-    GtsEdge * e = i->data;
-    HEAP_REMOVE_EDGE (heap, e);
-    HEAP_INSERT_EDGE (heap, e);
-    i = i->next;
-  }
-
-  g_slist_free (list);
-}
-
-static gdouble edge_length2 (GtsEdge * e)
-{
-  return gts_point_distance2 (GTS_POINT (GTS_SEGMENT (e)->v1), 
-			      GTS_POINT (GTS_SEGMENT (e)->v2));
-}
-
-static void create_heap_coarsen (GtsEdge * e, GtsEHeap * heap)
-{
-  HEAP_INSERT_EDGE (heap, e);
-}
-
-/**
- * gts_surface_coarsen:
- * @surface: a #GtsSurface.
- * @cost_func: a function returning the cost for a given edge.
- * @cost_data: user data to be passed to @cost_func.
- * @coarsen_func: a #GtsCoarsenVertexFunc.
- * @coarsen_data: user data to be passed to @coarsen_func.
- * @stop_func: a #GtsStopFunc.
- * @stop_data: user data to be passed to @stop_func.
- * @minangle: minimum angle between two neighboring triangles.
- *
- * The edges of @surface are sorted according to @cost_func to 
- * create a priority heap (a #GtsEHeap). The edges are extracted in
- * turn from the top of the heap and collapsed (i.e. the vertices are
- * replaced by the vertex returned by the @coarsen_func function)
- * until the @stop_func functions returns %TRUE.
- *
- * If @cost_func is set to %NULL, the edges are sorted according 
- * to their length squared (the shortest is on top).
- *
- * If @coarsen_func is set to %NULL gts_segment_midvertex() is used.
- *
- * The minimum angle is used to avoid introducing faces which would be folded.
- */
-void gts_surface_coarsen (GtsSurface * surface,
-			  GtsKeyFunc cost_func,
-			  gpointer cost_data,
-			  GtsCoarsenFunc coarsen_func,
-			  gpointer coarsen_data,
-			  GtsStopFunc stop_func,
-			  gpointer stop_data,
-			  gdouble minangle)
-{
-  GtsEHeap * heap;
-  GtsEdge * e;
-  gdouble top_cost;
-  gdouble maxcosine2;
-
-  g_return_if_fail (surface != NULL);
-  g_return_if_fail (stop_func != NULL);
-
-  if (cost_func == NULL)
-    cost_func = (GtsKeyFunc) edge_length2;
-  if (coarsen_func == NULL)
-    coarsen_func = (GtsCoarsenFunc) gts_segment_midvertex;
-
-  heap = gts_eheap_new (cost_func, cost_data);
-  maxcosine2 = cos (minangle); maxcosine2 *= maxcosine2;
-
-  gts_eheap_freeze (heap);
-  gts_surface_foreach_edge (surface, (GtsFunc) create_heap_coarsen, heap);
-  gts_eheap_thaw (heap);
-  /* we want to control edge destruction manually */
-  gts_allow_floating_edges = TRUE;
-  while ((e = gts_eheap_remove_top (heap, &top_cost)) &&
-	 (top_cost < G_MAXDOUBLE) &&
-	 !(*stop_func) (top_cost, gts_eheap_size (heap) - 
-			gts_edge_face_number (e, surface), stop_data))
-    {
-      GtsVertex * v = edge_collapse (e, heap, coarsen_func, coarsen_data,
-				     surface->vertex_class, maxcosine2);
-      if (v != NULL)
-	update_2nd_closest_neighbors (v, heap);
-    }
-  gts_allow_floating_edges = FALSE;
-
-  /* set reserved field of remaining edges back to NULL */
-  if (e) GTS_OBJECT (e)->reserved = NULL;
-  gts_eheap_foreach (heap, (GFunc) gts_object_reset_reserved, NULL);
-
-  gts_eheap_destroy (heap);
-}
-
-/**
- * gts_coarsen_stop_number:
- * @cost: the cost of the edge collapse considered.
- * @nedge: the current number of edges of the surface being simplified.
- * @min_number: a pointer to the minimum number of edges desired for the 
- * surface being simplified.
- *
- * This function is to be used as the @stop_func argument of 
- * gts_surface_coarsen() or gts_psurface_new().
- *
- * Returns: %TRUE if the edge collapse would create a surface with a smaller 
- * number of edges than given by @min_number, %FALSE otherwise.
- */
-gboolean gts_coarsen_stop_number (gdouble cost, 
-				  guint nedge, 
-				  guint * min_number)
-{
-  g_return_val_if_fail (min_number != NULL, TRUE);
-
-  if (nedge < *min_number)
-    return TRUE;
-  return FALSE;
-}
-
-/**
- * gts_coarsen_stop_cost:
- * @cost: the cost of the edge collapse considered.
- * @nedge: the current number of edges of the surface being simplified.
- * @max_cost: a pointer to the maximum cost allowed for an edge collapse.
- *
- * This function is to be used as the @stop_func argument of 
- * gts_surface_coarsen() or gts_psurface_new().
- *
- * Returns: %TRUE if the cost of the edge collapse considered is larger than
- * given by @max_cost, %FALSE otherwise.
- */
-gboolean gts_coarsen_stop_cost (gdouble cost, 
-				guint nedge, 
-				gdouble * max_cost)
-{
-  g_return_val_if_fail (max_cost != NULL, TRUE);
-
-  if (cost > *max_cost)
-    return TRUE;
-  return FALSE;
-}
-
-#define GTS_M_ICOSAHEDRON_X /* sqrt(sqrt(5)+1)/sqrt(2*sqrt(5)) */ \
-  0.850650808352039932181540497063011072240401406
-#define GTS_M_ICOSAHEDRON_Y /* sqrt(2)/sqrt(5+sqrt(5))         */ \
-  0.525731112119133606025669084847876607285497935
-#define GTS_M_ICOSAHEDRON_Z 0.0
-
-static guint generate_icosahedron (GtsSurface * s)
-{
-  GtsVertex * v01 = gts_vertex_new (s->vertex_class,
-      +GTS_M_ICOSAHEDRON_Z, +GTS_M_ICOSAHEDRON_X, -GTS_M_ICOSAHEDRON_Y);
-  GtsVertex * v02 = gts_vertex_new (s->vertex_class,
-      +GTS_M_ICOSAHEDRON_X, +GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z);
-  GtsVertex * v03 = gts_vertex_new (s->vertex_class,
-      +GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z, -GTS_M_ICOSAHEDRON_X);
-  GtsVertex * v04 = gts_vertex_new (s->vertex_class,
-      +GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z, +GTS_M_ICOSAHEDRON_X);
-  GtsVertex * v05 = gts_vertex_new (s->vertex_class,
-      +GTS_M_ICOSAHEDRON_X, -GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z);
-  GtsVertex * v06 = gts_vertex_new (s->vertex_class,
-      +GTS_M_ICOSAHEDRON_Z, +GTS_M_ICOSAHEDRON_X, +GTS_M_ICOSAHEDRON_Y);
-  GtsVertex * v07 = gts_vertex_new (s->vertex_class,
-      -GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z, +GTS_M_ICOSAHEDRON_X);
-  GtsVertex * v08 = gts_vertex_new (s->vertex_class,
-      +GTS_M_ICOSAHEDRON_Z, -GTS_M_ICOSAHEDRON_X, -GTS_M_ICOSAHEDRON_Y);
-  GtsVertex * v09 = gts_vertex_new (s->vertex_class,
-      -GTS_M_ICOSAHEDRON_X, +GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z);
-  GtsVertex * v10 = gts_vertex_new (s->vertex_class,
-      -GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z, -GTS_M_ICOSAHEDRON_X);
-  GtsVertex * v11 = gts_vertex_new (s->vertex_class,
-      -GTS_M_ICOSAHEDRON_X, -GTS_M_ICOSAHEDRON_Y, +GTS_M_ICOSAHEDRON_Z);
-  GtsVertex * v12 = gts_vertex_new (s->vertex_class,
-      +GTS_M_ICOSAHEDRON_Z, -GTS_M_ICOSAHEDRON_X, +GTS_M_ICOSAHEDRON_Y);
-
-  GtsEdge * e01 = gts_edge_new (s->edge_class, v01, v02);
-  GtsEdge * e02 = gts_edge_new (s->edge_class, v03, v02);
-  GtsEdge * e03 = gts_edge_new (s->edge_class, v01, v03);
-  GtsEdge * e04 = gts_edge_new (s->edge_class, v04, v05);
-  GtsEdge * e05 = gts_edge_new (s->edge_class, v02, v05);
-  GtsEdge * e06 = gts_edge_new (s->edge_class, v04, v02);
-  GtsEdge * e07 = gts_edge_new (s->edge_class, v06, v07);
-  GtsEdge * e08 = gts_edge_new (s->edge_class, v04, v07);
-  GtsEdge * e09 = gts_edge_new (s->edge_class, v06, v04);
-  GtsEdge * e10 = gts_edge_new (s->edge_class, v08, v03);
-  GtsEdge * e11 = gts_edge_new (s->edge_class, v03, v05);
-  GtsEdge * e12 = gts_edge_new (s->edge_class, v08, v05);
-  GtsEdge * e13 = gts_edge_new (s->edge_class, v06, v09);
-  GtsEdge * e14 = gts_edge_new (s->edge_class, v07, v09);
-  GtsEdge * e15 = gts_edge_new (s->edge_class, v08, v10);
-  GtsEdge * e16 = gts_edge_new (s->edge_class, v03, v10);
-  GtsEdge * e17 = gts_edge_new (s->edge_class, v06, v01);
-  GtsEdge * e18 = gts_edge_new (s->edge_class, v01, v09);
-  GtsEdge * e19 = gts_edge_new (s->edge_class, v08, v11);
-  GtsEdge * e20 = gts_edge_new (s->edge_class, v10, v11);
-  GtsEdge * e21 = gts_edge_new (s->edge_class, v06, v02);
-  GtsEdge * e22 = gts_edge_new (s->edge_class, v12, v11);
-  GtsEdge * e23 = gts_edge_new (s->edge_class, v12, v08);
-  GtsEdge * e24 = gts_edge_new (s->edge_class, v12, v07);
-  GtsEdge * e25 = gts_edge_new (s->edge_class, v07, v11);
-  GtsEdge * e26 = gts_edge_new (s->edge_class, v12, v04);
-  GtsEdge * e27 = gts_edge_new (s->edge_class, v09, v11);
-  GtsEdge * e28 = gts_edge_new (s->edge_class, v10, v09);
-  GtsEdge * e29 = gts_edge_new (s->edge_class, v12, v05);
-  GtsEdge * e30 = gts_edge_new (s->edge_class, v01, v10);
-  
-  gts_surface_add_face (s, gts_face_new (s->face_class, e01, e02, e03));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e04, e05, e06));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e07, e08, e09));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e10, e11, e12));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e13, e14, e07));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e15, e16, e10));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e17, e18, e13));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e19, e20, e15));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e21, e01, e17));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e22, e19, e23));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e09, e06, e21));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e24, e25, e22));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e26, e08, e24));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e20, e27, e28));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e29, e04, e26));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e14, e27, e25));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e23, e12, e29));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e02, e05, e11));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e30, e28, e18));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e03, e16, e30));
-
-  return 0;
-}
-
-static GtsVertex * unit_sphere_arc_midvertex (GtsSegment * s, 
-					      GtsVertexClass * vertex_class)
-{
-  GtsPoint * p1, * p2;
-  gdouble x, y, z, norm;
-
-  p1 = GTS_POINT (s->v1); p2 = GTS_POINT (s->v2);
-
-  x = 0.5*(p1->x + p2->x);
-  y = 0.5*(p1->y + p2->y);
-  z = 0.5*(p1->z + p2->z);
-
-  norm = x*x + y*y + z*z;
-  norm = sqrt (norm);
-
-  x /= norm; y /= norm; z /= norm;
-
-  return gts_vertex_new (vertex_class, x, y, z);
-}
-
-static void tessellate_face (GtsFace * f,
-			     GtsSurface * s,
-			     GtsRefineFunc refine_func,
-			     gpointer refine_data,
-			     GtsVertexClass * vertex_class,
-			     GtsEdgeClass * edge_class)
-{
-  GtsTriangle * t;
-  GtsEdge * e1, * e2, * e3;                          /* former edges     */
-  GtsVertex * v1, * v2, * v3;                        /* initial vertices */
-  GtsVertex * v4, * v5, * v6;                        /* new vertices     */ 
-  GtsEdge * e56, * e64, * e45;                       /* new inside edges */
-  GtsEdge * e24, * e34, * e35, * e15, * e16, * e26;  /* new border edges */
-  GSList * dum;
-  GtsEdge * edum;
-  
-  t = GTS_TRIANGLE (f);
-  e1 = t->e1; e2 = t->e2; e3 = t->e3;
-
-  if (GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v1) {
-    v1 = GTS_SEGMENT (e2)->v2;
-    v2 = GTS_SEGMENT (e1)->v1;
-    v3 = GTS_SEGMENT (e1)->v2;
-  }
-  else if (GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v2) {
-    v1 = GTS_SEGMENT (e2)->v1;
-    v2 = GTS_SEGMENT (e1)->v1;
-    v3 = GTS_SEGMENT (e1)->v2;
-  }
-  else if (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e2)->v1) {
-    v1 = GTS_SEGMENT (e2)->v2;
-    v2 = GTS_SEGMENT (e1)->v2;
-    v3 = GTS_SEGMENT (e1)->v1;
-  }
-  else if (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e2)->v2) {
-    v1 = GTS_SEGMENT (e2)->v1;
-    v2 = GTS_SEGMENT (e1)->v2;
-    v3 = GTS_SEGMENT (e1)->v1;
-  }
-  else {
-    v1 = v2 = v3 = NULL;
-    g_assert_not_reached ();
-  }
-
-  e1->triangles = g_slist_remove (e1->triangles, t);
-  e2->triangles = g_slist_remove (e2->triangles, t);
-  e3->triangles = g_slist_remove (e3->triangles, t);
-  
-  if (GTS_OBJECT (e1)->reserved) {
-    dum = (GTS_OBJECT (e1)->reserved);
-    e24 = dum->data;
-    e34 = dum->next->data;
-    v4 = GTS_SEGMENT (e24)->v2;
-    if (GTS_SEGMENT (e24)->v1 == v3) {
-      edum = e34; e34 = e24; e24 = edum;
-    }
-  }
-  else {
-    v4 = (*refine_func) (e1, vertex_class, refine_data);
-    e24 = gts_edge_new (edge_class, v2, v4);
-    e34 = gts_edge_new (edge_class, v3, v4);
-    dum = g_slist_append (NULL, e24);
-    dum = g_slist_append (dum,  e34);
-    GTS_OBJECT (e1)->reserved = dum;
-  }
-  if (GTS_OBJECT (e2)->reserved) {
-    dum = (GTS_OBJECT (e2)->reserved);
-    e35 = dum->data;
-    e15 = dum->next->data;
-    v5 = GTS_SEGMENT (e35)->v2;
-    if (GTS_SEGMENT (e35)->v1 == v1) {
-      edum = e15; e15 = e35; e35 = edum;
-    }
-  }
-  else {
-    v5 = (*refine_func) (e2, vertex_class, refine_data);
-    e35 = gts_edge_new (edge_class, v3, v5);
-    e15 = gts_edge_new (edge_class, v1, v5);
-    dum = g_slist_append (NULL, e35);
-    dum = g_slist_append (dum,  e15);
-    GTS_OBJECT (e2)->reserved = dum;
-  }
-  if (GTS_OBJECT (e3)->reserved) {
-    dum = (GTS_OBJECT (e3)->reserved);
-    e16 = dum->data;
-    e26 = dum->next->data;
-    v6 = GTS_SEGMENT (e16)->v2;
-    if (GTS_SEGMENT (e16)->v1 == v2) {
-      edum = e16; e16 = e26; e26 = edum;
-    }
-  }
-  else {
-    v6 = (*refine_func) (e3, vertex_class, refine_data);
-    e16 = gts_edge_new (edge_class, v1, v6);
-    e26 = gts_edge_new (edge_class, v2, v6);
-    dum = g_slist_append (NULL, e16);
-    dum = g_slist_append (dum,  e26);
-    GTS_OBJECT (e3)->reserved = dum;
-  }
-  
-  if (e1->triangles == NULL) {
-    g_slist_free (GTS_OBJECT (e1)->reserved);
-    GTS_OBJECT (e1)->reserved = NULL;
-    gts_object_destroy (GTS_OBJECT (e1));
-    e1 = NULL;
-  }
-  if (e2->triangles == NULL) {
-    g_slist_free (GTS_OBJECT (e2)->reserved);
-    GTS_OBJECT (e2)->reserved = NULL;
-    gts_object_destroy (GTS_OBJECT (e2));
-    e2 = NULL;
-  }
-  if (e3->triangles == NULL) {
-    g_slist_free (GTS_OBJECT (e3)->reserved);
-    GTS_OBJECT (e3)->reserved = NULL;
-    gts_object_destroy (GTS_OBJECT (e3));
-    e3 = NULL;
-  }
-
-  e56 = gts_edge_new (edge_class, v5, v6);
-  e64 = gts_edge_new (edge_class, v6, v4);
-  e45 = gts_edge_new (edge_class, v4, v5);
-  t->e1 = e56; e56->triangles = g_slist_prepend (e56->triangles, t);
-  t->e2 = e64; e64->triangles = g_slist_prepend (e64->triangles, t);
-  t->e3 = e45; e45->triangles = g_slist_prepend (e45->triangles, t);
-  
-  gts_surface_add_face (s, gts_face_new (s->face_class, e16, e56, e15));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e26, e24, e64));
-  gts_surface_add_face (s, gts_face_new (s->face_class, e45, e34, e35)); 
-}
-
-static void create_array_tessellate (GtsFace * f, GPtrArray * array)
-{
-  g_ptr_array_add (array, f);
-}
-
-/**
- * gts_surface_tessellate:
- * @s: a #GtsSurface.
- * @refine_func: a #GtsRefineFunc.
- * @refine_data: user data to be passed to @refine_func.
- *
- * Tessellate each triangle of @s with 4 triangles:   
- * the number of triangles is increased by a factor of 4.
- * http://mathworld.wolfram.com/GeodesicDome.html
- *
- * If @refine_func is set to %NULL a mid arc function is used: if
- * the surface is a polyhedron with the unit sphere as circum sphere,
- * then gts_surface_tessellate() corresponds to a geodesation step
- * (see gts_surface_generate_sphere()).
- * 
- */
-void gts_surface_tessellate (GtsSurface * s,
-			     GtsRefineFunc refine_func,
-			     gpointer refine_data)
-{
-  GPtrArray * array;
-  guint i;
-
-  g_return_if_fail (s != NULL);
-  
-  if (refine_func == NULL) /* tessellate_surface == geodesate_surface */
-    refine_func = (GtsRefineFunc) unit_sphere_arc_midvertex;
-
-  array = g_ptr_array_new ();
-  gts_surface_foreach_face (s, (GtsFunc) create_array_tessellate, array);
-  for(i = 0; i < array->len; i++)
-    tessellate_face (g_ptr_array_index (array, i),
-		     s, refine_func, refine_data, 
-		     s->vertex_class, s->edge_class);
-  g_ptr_array_free (array, TRUE);
-}
-
-/**
- * gts_surface_generate_sphere:
- * @s: a #GtsSurface.
- * @geodesation_order: a #guint.
- *
- * Add a triangulated unit sphere generated by recursive subdivision to @s.
- * First approximation is an isocahedron; each level of refinement
- * (@geodesation_order) increases the number of triangles by a factor of 4.
- * http://mathworld.wolfram.com/GeodesicDome.html
- *
- * Returns: @s.
- */
-GtsSurface * gts_surface_generate_sphere (GtsSurface * s, 
-					  guint geodesation_order)
-{
-  guint cgo; 
-
-  g_return_val_if_fail (s != NULL, NULL);
-  g_return_val_if_fail (geodesation_order != 0, NULL);
-
-  generate_icosahedron (s);
-
-  for (cgo = 1; cgo < geodesation_order; cgo++)
-    gts_surface_tessellate (s, NULL, NULL);
-  
-  return s;
-}
-
-static void foreach_vertex_copy (GtsPoint * p, GtsVertexClass * klass)
-{
-  GTS_OBJECT (p)->reserved = gts_vertex_new (klass, p->x, p->y, p->z);
-}
-
-static void foreach_edge_copy (GtsSegment * s, GtsEdgeClass * klass)
-{
-  GTS_OBJECT (s)->reserved = gts_edge_new (klass,
-					   GTS_OBJECT (s->v1)->reserved, 
-					   GTS_OBJECT (s->v2)->reserved);
-}
-
-static void foreach_face_copy (GtsTriangle * t,
-			       GtsSurface * s)
-{
-  gts_surface_add_face (s, gts_face_new (s->face_class,
-					 GTS_OBJECT (t->e1)->reserved,
-					 GTS_OBJECT (t->e2)->reserved,
-					 GTS_OBJECT (t->e3)->reserved));
-}
-
-/**
- * gts_surface_copy:
- * @s1: a #GtsSurface.
- * @s2: a #GtsSurface.
- *
- * Add a copy of all the faces, edges and vertices of @s2 to @s1.
- *
- * Returns: @s1.
- */
-GtsSurface * gts_surface_copy (GtsSurface * s1, GtsSurface * s2)
-{
-  g_return_val_if_fail (s1 != NULL, NULL);
-  g_return_val_if_fail (s2 != NULL, NULL);
-  
-  gts_surface_foreach_vertex (s2, (GtsFunc) foreach_vertex_copy, 
-			      s1->vertex_class);
-  gts_surface_foreach_edge (s2, (GtsFunc) foreach_edge_copy, s1->edge_class);
-  gts_surface_foreach_face (s2, (GtsFunc) foreach_face_copy, s1);
-
-  gts_surface_foreach_vertex (s2, (GtsFunc) gts_object_reset_reserved, NULL);
-  gts_surface_foreach_edge (s2, (GtsFunc) gts_object_reset_reserved, NULL);
-  
-  return s1;
-}
-
-static void merge_foreach_face (GtsFace * f, 
-				GtsSurface * s)
-{
-  gts_surface_add_face (s, f);
-}
-
-/**
- * gts_surface_merge:
- * @s: a #GtsSurface.
- * @with: another #GtsSurface.
- *
- * Adds all the faces of @with which do not already belong to @s
- * to @s.
- */
-void gts_surface_merge (GtsSurface * s, GtsSurface * with)
-{
-  g_return_if_fail (s != NULL);
-  g_return_if_fail (with != NULL);
-  
-  gts_surface_foreach_face (with, (GtsFunc) merge_foreach_face, s);
-}
-
-static void manifold_foreach_edge (GtsEdge * e, gpointer * data)
-{
-  gboolean * is_manifold = data[0];
-
-  if (*is_manifold) {
-    if (gts_edge_face_number (e, data[1]) > 2)
-      *is_manifold = FALSE;
-  }
-}
-
-/**
- * gts_surface_is_manifold:
- * @s: a #GtsSurface.
- *
- * Returns: %TRUE if the surface is a manifold, %FALSE otherwise.
- */
-gboolean gts_surface_is_manifold (GtsSurface * s)
-{
-  gboolean is_manifold = TRUE;
-  gpointer data[2];
-
-  g_return_val_if_fail (s != NULL, FALSE);
-
-  data[0] = &is_manifold;
-  data[1] = s;
-  gts_surface_foreach_edge (s, (GtsFunc) manifold_foreach_edge, data);
-  return is_manifold;
-}
-
-static void closed_foreach_edge (GtsEdge * e, gpointer * data)
-{
-  gboolean * is_closed = data[0];
-
-  if (*is_closed) {
-    if (gts_edge_face_number (e, data[1]) != 2)
-      *is_closed = FALSE;
-  }
-}
-
-/**
- * gts_surface_is_closed:
- * @s: a #GtsSurface.
- *
- * Returns: %TRUE if @s is a closed surface, %FALSE otherwise. Note that a
- * closed surface is also a manifold.
- */
-gboolean gts_surface_is_closed (GtsSurface * s)
-{
-  gboolean is_closed = TRUE;
-  gpointer data[2];
-
-  g_return_val_if_fail (s != NULL, FALSE);
-
-  data[0] = &is_closed;
-  data[1] = s;
-  gts_surface_foreach_edge (s, (GtsFunc) closed_foreach_edge, data);
-  return is_closed;
-}
-
-static void orientable_foreach_edge (GtsEdge * e, gpointer * data)
-{
-  gboolean * is_orientable = data[0];
-
-  if (*is_orientable) {
-    GtsSurface * surface = data[1];
-    GtsFace * f1 = NULL, * f2 = NULL;
-    GSList * i = e->triangles;
-    while (i && *is_orientable) {
-      GtsFace * f = i->data;
-      if (GTS_IS_FACE (f) && gts_face_has_parent_surface (f, surface)) {
-	if (!f1) f1 = f;
-	else if (!f2) f2 = f;
-	else *is_orientable = FALSE;
-      }
-      i = i->next;
-    }
-    if (f1 && f2 && !gts_triangles_are_compatible (GTS_TRIANGLE (f1), 
-						   GTS_TRIANGLE (f2), e))
-      *is_orientable = FALSE;
-  }
-}
-
-/**
- * gts_surface_is_orientable:
- * @s: a #GtsSurface.
- *
- * Returns: %TRUE if all the faces of @s have compatible orientation
- * as checked by gts_faces_are_compatible(), %FALSE otherwise. Note that
- * an orientable surface is also a manifold.
- */
-gboolean gts_surface_is_orientable (GtsSurface * s)
-{
-  gboolean is_orientable = TRUE;
-  gpointer data[2];
-
-  g_return_val_if_fail (s != NULL, FALSE);
-
-  data[0] = &is_orientable;
-  data[1] = s;
-  gts_surface_foreach_edge (s, (GtsFunc) orientable_foreach_edge, data);
-  return is_orientable;
-}
-
-static void volume_foreach_face (GtsTriangle * t,
-				 gdouble * volume)
-{
-  GtsVertex * va, * vb, * vc;
-  GtsPoint * pa, * pb, * pc;
-
-  gts_triangle_vertices (t, &va, &vb, &vc);
-  pa = GTS_POINT (va);
-  pb = GTS_POINT (vb);
-  pc = GTS_POINT (vc);
-  
-  *volume += (pa->x * (pb->y * pc->z - pb->z * pc->y) +
-	      pb->x * (pc->y * pa->z - pc->z * pa->y) +
-	      pc->x * (pa->y * pb->z - pa->z * pb->y));
-}
-
-/**
- * gts_surface_volume:
- * @s: a #GtsSurface.
- *
- * Returns: the signed volume of the domain bounded by the surface @s. It
- * makes sense only if @s is a closed and orientable manifold.
- */
-gdouble gts_surface_volume (GtsSurface * s)
-{
-  gdouble volume = 0.0;
-
-  g_return_val_if_fail (s != NULL, 0.0);
-
-  gts_surface_foreach_face (s, (GtsFunc) volume_foreach_face, &volume);
-
-  return volume/6.;
-}
-
-static void center_of_mass_foreach_face (GtsTriangle * t,
-					 gpointer * data)
-{
-  GtsVertex * v1, * v2, * v3;
-  GtsPoint * p1, * p2, * p3;
-  gdouble x1, y1, z1, x2, y2, z2, nx, ny, nz;
-  gdouble * volume = data[0];
-  gdouble * cm = data[1];
-
-  gts_triangle_vertices (t, &v1, &v2, &v3);
-  p1 = GTS_POINT (v1);
-  p2 = GTS_POINT (v2);
-  p3 = GTS_POINT (v3);
-
-  x1 = p2->x - p1->x;
-  y1 = p2->y - p1->y;
-  z1 = p2->z - p1->z;
-
-  x2 = p3->x - p1->x;
-  y2 = p3->y - p1->y;
-  z2 = p3->z - p1->z;
-  
-  nx = y1*z2 - z1*y2;
-  ny = z1*x2 - x1*z2;
-  nz = x1*y2 - y1*x2;
-
-  cm[0] += nx*(p1->x*p1->x + p2->x*p2->x + p3->x*p3->x + 
-	       p1->x*p2->x + p1->x*p3->x + p2->x*p3->x);
-  cm[1] += ny*(p1->y*p1->y + p2->y*p2->y + p3->y*p3->y + 
-	       p1->y*p2->y + p1->y*p3->y + p2->y*p3->y);
-  cm[2] += nz*(p1->z*p1->z + p2->z*p2->z + p3->z*p3->z + 
-	       p1->z*p2->z + p1->z*p3->z + p2->z*p3->z);
-
-  *volume += nx*(p1->x + p2->x + p3->x);
-}
-
-
-/**
- * gts_surface_center_of_mass:
- * @s: a #GtsSurface.
- * @cm: a #GtsVector.
- *
- * Fills @cm with the coordinates of the center of mass of @s.
- *
- * Returns: the signed volume of the domain bounded by the surface @s.
- */
-gdouble gts_surface_center_of_mass (GtsSurface * s,
-				    GtsVector cm)
-{
-  gdouble volume = 0.;
-  gpointer data[2];
-
-  g_return_val_if_fail (s != NULL, 0.0);
-
-  data[0] = &volume;
-  data[1] = &(cm[0]);
-  cm[0] = cm[1] = cm[2] = 0.;
-  gts_surface_foreach_face (s, (GtsFunc) center_of_mass_foreach_face, data);
-  
-  if (volume != 0.) {
-    cm[0] /= 4.*volume;
-    cm[1] /= 4.*volume;
-    cm[2] /= 4.*volume;
-  }
-
-  return volume/6.;
-}
-
-static void center_of_area_foreach_face (GtsTriangle * t,
-					 gpointer * data)
-{
-  GtsVertex * v1, * v2, * v3;
-  GtsPoint * p1, * p2, * p3;
-  gdouble a;
-  gdouble * area = data[0];
-  gdouble * cm = data[1];
-
-  gts_triangle_vertices (t, &v1, &v2, &v3);
-  p1 = GTS_POINT (v1);
-  p2 = GTS_POINT (v2);
-  p3 = GTS_POINT (v3);
-
-  a = gts_triangle_area (t);
-  cm[0] += a*(p1->x + p2->x + p3->x);
-  cm[1] += a*(p1->y + p2->y + p3->y);
-  cm[2] += a*(p1->z + p2->z + p3->z);
-  *area += a;
-}
-
-
-/**
- * gts_surface_center_of_area:
- * @s: a #GtsSurface.
- * @cm: a #GtsVector.
- *
- * Fills @cm with the coordinates of the center of area of @s.
- *
- * Returns: the area of surface @s.
- */
-gdouble gts_surface_center_of_area (GtsSurface * s,
-				    GtsVector cm)
-{
-  gdouble area = 0.;
-  gpointer data[2];
-
-  g_return_val_if_fail (s != NULL, 0.0);
-
-  data[0] = &area;
-  data[1] = &(cm[0]);
-  cm[0] = cm[1] = cm[2] = 0.;
-  gts_surface_foreach_face (s, (GtsFunc) center_of_area_foreach_face, data);
-  
-  if (area != 0.) {
-    cm[0] /= 3.*area;
-    cm[1] /= 3.*area;
-    cm[2] /= 3.*area;
-  }
-
-  return area;
-}
-
-static void number_foreach (gpointer data, guint * n)
-{
-  (*n)++;
-}
-
-/**
- * gts_surface_vertex_number:
- * @s: a #GtsSurface.
- *
- * Returns: the number of vertices of @s.
- */
-guint gts_surface_vertex_number (GtsSurface * s)
-{
-  guint n = 0;
-
-  g_return_val_if_fail (s != NULL, 0);
-
-  gts_surface_foreach_vertex (s, (GtsFunc) number_foreach, &n);
-
-  return n;
-}
-
-/**
- * gts_surface_edge_number:
- * @s: a #GtsSurface.
- *
- * Returns: the number of edges of @s.
- */
-guint gts_surface_edge_number (GtsSurface * s)
-{
-  guint n = 0;
-
-  g_return_val_if_fail (s != NULL, 0);
-
-  gts_surface_foreach_edge (s, (GtsFunc) number_foreach, &n);
-
-  return n;
-}
-
-/**
- * gts_surface_face_number:
- * @s: a #GtsSurface.
- *
- * Returns: the number of faces of @s
- */
-guint gts_surface_face_number (GtsSurface * s)
-{
-  g_return_val_if_fail (s != NULL, 0);
-
-#ifdef USE_SURFACE_BTREE
-  return g_tree_nnodes (s->faces);
-#else /* not USE_SURFACE_BTREE */
-  return g_hash_table_size (s->faces);
-#endif /* not USE_SURFACE_BTREE */
-}
-
-static void build_list_face (GtsTriangle * t, GSList ** list)
-{
-  *list = g_slist_prepend (*list, gts_bbox_triangle (gts_bbox_class (), t));
-}
-
-static void build_list_boundary (GtsEdge * e, GSList ** list)
-{
-  if (gts_edge_is_boundary (e, NULL))
-    *list = g_slist_prepend (*list, gts_bbox_segment (gts_bbox_class (),
-						      GTS_SEGMENT (e)));
-}
-
-/**
- * gts_surface_distance:
- * @s1: a #GtsSurface.
- * @s2: a #GtsSurface.
- * @delta: a spatial increment defined as the percentage of the diagonal
- * of the bounding box of @s2.
- * @face_range: a #GtsRange.
- * @boundary_range: a #GtsRange.
- *
- * Using the gts_bb_tree_surface_distance() and
- * gts_bb_tree_surface_boundary_distance() functions fills @face_range
- * and @boundary_range with the min, max and average Euclidean
- * (minimum) distances between the faces of @s1 and the faces of @s2
- * and between the boundary edges of @s1 and @s2.  
- */
-void gts_surface_distance (GtsSurface * s1, GtsSurface * s2, gdouble delta,
-			   GtsRange * face_range, GtsRange * boundary_range)
-{
-  GNode * face_tree, * boundary_tree;
-  GSList * bboxes;
-
-  g_return_if_fail (s1 != NULL);
-  g_return_if_fail (s2 != NULL);
-  g_return_if_fail (delta > 0. && delta < 1.);
-  g_return_if_fail (face_range != NULL);
-  g_return_if_fail (boundary_range != NULL);
-
-  bboxes = NULL;
-  gts_surface_foreach_face (s2, (GtsFunc) build_list_face, &bboxes);
-  if (bboxes != NULL) {
-    face_tree = gts_bb_tree_new (bboxes);
-    g_slist_free (bboxes);
-    
-    gts_bb_tree_surface_distance (face_tree, s1, 
-			       (GtsBBoxDistFunc) gts_point_triangle_distance,
-				  delta, face_range);
-    gts_bb_tree_destroy (face_tree, TRUE);
-    
-    bboxes = NULL;
-    gts_surface_foreach_edge (s2, (GtsFunc) build_list_boundary, &bboxes);
-    if (bboxes != NULL) {
-      boundary_tree = gts_bb_tree_new (bboxes);
-      g_slist_free (bboxes);
-
-      gts_bb_tree_surface_boundary_distance (boundary_tree,
-	       s1, 
-	       (GtsBBoxDistFunc) gts_point_segment_distance,
-	       delta, boundary_range);
-      gts_bb_tree_destroy (boundary_tree, TRUE);
-    }
-    else
-      gts_range_reset (boundary_range);
-  }
-  else {
-    gts_range_reset (face_range);
-    gts_range_reset (boundary_range);
-  }
-}
-
-static void surface_boundary (GtsEdge * e, gpointer * data)
-{
-  GSList ** list = data[0];
-
-  if (gts_edge_is_boundary (e, data[1]))
-    *list = g_slist_prepend (*list, e);
-}
-
-/**
- * gts_surface_boundary:
- * @surface: a #GtsSurface.
- *
- * Returns: a list of #GtsEdge boundary of @surface.
- */
-GSList * gts_surface_boundary (GtsSurface * surface)
-{
-  GSList * list = NULL;
-  gpointer data[2];
-
-  g_return_val_if_fail (surface != NULL, NULL);
-
-  data[0] = &list;
-  data[1] = surface;
-  gts_surface_foreach_edge (surface, (GtsFunc) surface_boundary, data);
-  
-  return list;
-}
-
-struct _GtsSurfaceTraverse {
-  GtsFifo * q;
-  GtsSurface * s;
-};
-
-/**
- * gts_surface_traverse_new:
- * @s: a #GtsSurface.
- * @f: a #GtsFace belonging to @s.
- *
- * Returns: a new #GtsSurfaceTraverse, initialized to start traversing
- * from face @f of surface @s.  
- */
-GtsSurfaceTraverse * gts_surface_traverse_new (GtsSurface * s,
-					       GtsFace * f)
-{
-  GtsSurfaceTraverse * t;
-
-  g_return_val_if_fail (s != NULL, NULL);
-  g_return_val_if_fail (f != NULL, NULL);
-  g_return_val_if_fail (gts_face_has_parent_surface (f, s), NULL);
-  
-  t = g_malloc (sizeof (GtsSurfaceTraverse));
-  t->q = gts_fifo_new ();
-  t->s = s;
-  GTS_OBJECT (f)->reserved = GUINT_TO_POINTER (1);
-  gts_fifo_push (t->q, f);
-  return t;
-}
-
-static void push_neighbor (GtsFace * v, gpointer * data)
-{
-  if (!GTS_OBJECT (v)->reserved) {
-    GTS_OBJECT (v)->reserved = 
-      GUINT_TO_POINTER (GPOINTER_TO_UINT (GTS_OBJECT (data[1])->reserved) + 1);
-    gts_fifo_push (data[0], v);
-  }
-}
-
-/**
- * gts_surface_traverse_next:
- * @t: a #GtsSurfaceTraverse.
- * @level: a pointer to a guint or %NULL.
- *
- * Returns: the next face of the traversal in breadth-first order or
- * %NULL if no faces are left. If @level if not %NULL, it is filled
- * with the level of the returned face (0 for the initial face, 1 for
- * its neighbors and so on).  
- */
-GtsFace * gts_surface_traverse_next (GtsSurfaceTraverse * t,
-				     guint * level)
-{
-  GtsFace * u;
-
-  g_return_val_if_fail (t != NULL, NULL);
-
-  u = gts_fifo_pop (t->q);
-  if (u) {
-    gpointer data[2];
-
-    if (level)
-      *level = GPOINTER_TO_UINT (GTS_OBJECT (u)->reserved);
-    data[0] = t->q;
-    data[1] = u;
-    gts_face_foreach_neighbor (u, t->s, (GtsFunc) push_neighbor, data);
-  }
-  return u;
-}
-
-/**
- * gts_surface_traverse_destroy:
- * @t: a #GtsSurfaceTraverse.
- *
- * Frees all the memory allocated for @t.
- */
-void gts_surface_traverse_destroy (GtsSurfaceTraverse * t)
-{
-  g_return_if_fail (t != NULL);
-
-  gts_surface_foreach_face (t->s, (GtsFunc) gts_object_reset_reserved, NULL);
-  gts_fifo_destroy (t->q);
-  g_free (t);
-}
-
-static void traverse_manifold (GtsTriangle * t, GtsSurface * s)
-{
-  if (g_slist_length (GTS_FACE (t)->surfaces) > 1)
-    return;
-
-  gts_surface_add_face (s, GTS_FACE (t));
-  if (g_slist_length (t->e1->triangles) == 2) {
-    if (t->e1->triangles->data != t)
-      traverse_manifold (t->e1->triangles->data, s);
-    else
-      traverse_manifold (t->e1->triangles->next->data, s);
-  }
-  if (g_slist_length (t->e2->triangles) == 2) {
-    if (t->e2->triangles->data != t)
-      traverse_manifold (t->e2->triangles->data, s);
-    else
-      traverse_manifold (t->e2->triangles->next->data, s);
-  }
-  if (g_slist_length (t->e3->triangles) == 2) {
-    if (t->e3->triangles->data != t)
-      traverse_manifold (t->e3->triangles->data, s);
-    else
-      traverse_manifold (t->e3->triangles->next->data, s);
-  }
-}
-
-static void non_manifold_edges (GtsEdge * e, gpointer * data)
-{
-  GtsSurface * s = data[0];
-  GSList ** non_manifold = data[1];
-
-  if (gts_edge_face_number (e, s) > 2) {
-    GSList * i = e->triangles;
-
-    while (i) {
-      if (gts_face_has_parent_surface (i->data, s) &&
-	  !g_slist_find (*non_manifold, i->data))
-	*non_manifold = g_slist_prepend (*non_manifold, i->data);
-      i = i->next;
-    }
-  }
-}
-
-static void traverse_boundary (GtsEdge * e, gpointer * data)
-{
-  GtsSurface * orig = data[0];
-  GSList ** components = data[1];
-  GtsFace * f = gts_edge_is_boundary (e, orig);
-
-  if (f != NULL && g_slist_length (f->surfaces) == 1) {
-    GtsSurface * s = 
-      gts_surface_new (GTS_SURFACE_CLASS (GTS_OBJECT (orig)->klass),
-		       orig->face_class,
-		       orig->edge_class,
-		       orig->vertex_class);
-    GSList * non_manifold = NULL, * i;
-    gpointer data[2];
-
-    *components = g_slist_prepend (*components, s);
-    data[0] = s;
-    data[1] = &non_manifold;
-    traverse_manifold (GTS_TRIANGLE (f), s);
-
-    gts_surface_foreach_edge (s, (GtsFunc) non_manifold_edges, data);
-    i = non_manifold;
-    while (i) {
-      gts_surface_remove_face (s, i->data);
-      i = i->next;
-    }
-    g_slist_free (non_manifold);
-  }
-}
-
-static void traverse_remaining (GtsFace * f, gpointer * data)
-{
-  GtsSurface * orig = data[0];
-  GSList ** components = data[1];
-
-  if (g_slist_length (f->surfaces) == 1) {
-    GtsSurface * s = 
-      gts_surface_new (GTS_SURFACE_CLASS (GTS_OBJECT (orig)->klass),
-		       orig->face_class,
-		       orig->edge_class,
-		       orig->vertex_class);
-    GSList * non_manifold = NULL, * i;
-    gpointer data[2];
-
-    *components = g_slist_prepend (*components, s);
-    data[0] = s;
-    data[1] = &non_manifold;
-    traverse_manifold (GTS_TRIANGLE (f), s);
-
-    gts_surface_foreach_edge (s, (GtsFunc) non_manifold_edges, data);
-    i = non_manifold;
-    while (i) {
-      gts_surface_remove_face (s, i->data);
-      i = i->next;
-    }
-    g_slist_free (non_manifold);
-  }
-}
-
-/**
- * gts_surface_split:
- * @s: a #GtsSurface.
- *
- * Splits a surface into connected and manifold components.
- * 
- * Returns: a list of new #GtsSurface.
- */
-GSList * gts_surface_split (GtsSurface * s)
-{
-  gpointer data[2];
-  GSList * components = NULL;
-
-  g_return_val_if_fail (s != NULL, NULL);
-
-  data[0] = s;
-  data[1] = &components;
-
-  /* boundary components */
-  gts_surface_foreach_edge (s, (GtsFunc) traverse_boundary, data);
-
-  /* remaining components */
-  gts_surface_foreach_face (s, (GtsFunc) traverse_remaining, data);
-
-  return components;
-}
diff --git a/src/gts/triangle.c b/src/gts/triangle.c
deleted file mode 100644
index 5213a51..0000000
--- a/src/gts/triangle.c
+++ /dev/null
@@ -1,1094 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <math.h>
-#include "gts.h"
-
-static void triangle_destroy (GtsObject * object)
-{
-  GtsTriangle * triangle = GTS_TRIANGLE (object);
-  GtsEdge * e1 = triangle->e1;
-  GtsEdge * e2 = triangle->e2;
-  GtsEdge * e3 = triangle->e3;
-
-  e1->triangles = g_slist_remove (e1->triangles, triangle);
-  if (!GTS_OBJECT_DESTROYED (e1) &&
-      !gts_allow_floating_edges && e1->triangles == NULL)
-    gts_object_destroy (GTS_OBJECT (e1));
-  
-  e2->triangles = g_slist_remove (e2->triangles, triangle);
-  if (!GTS_OBJECT_DESTROYED (e2) &&
-      !gts_allow_floating_edges && e2->triangles == NULL)
-    gts_object_destroy (GTS_OBJECT (e2));
-  
-  e3->triangles = g_slist_remove (e3->triangles, triangle);
-  if (!GTS_OBJECT_DESTROYED (e3) &&
-      !gts_allow_floating_edges && e3->triangles == NULL)
-    gts_object_destroy (GTS_OBJECT (e3));
-
-  (* GTS_OBJECT_CLASS (gts_triangle_class ())->parent_class->destroy) (object);
-}
-
-static void triangle_class_init (GtsObjectClass * klass)
-{
-  klass->destroy = triangle_destroy;
-}
-
-static void triangle_init (GtsTriangle * triangle)
-{
-  triangle->e1 = triangle->e2 = triangle->e3 = NULL;
-}
-
-/**
- * gts_triangle_class:
- *
- * Returns: the #GtsTriangleClass.
- */
-GtsTriangleClass * gts_triangle_class (void)
-{
-  static GtsTriangleClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo triangle_info = {
-      "GtsTriangle",
-      sizeof (GtsTriangle),
-      sizeof (GtsTriangleClass),
-      (GtsObjectClassInitFunc) triangle_class_init,
-      (GtsObjectInitFunc) triangle_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (gts_object_class (), 
-				  &triangle_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_triangle_set:
- * @triangle: a #GtsTriangle.
- * @e1: a #GtsEdge.
- * @e2: another #GtsEdge touching @e1.
- * @e3: another #GtsEdge touching both @e1 and @e2.
- *
- * Sets the edge of @triangle to @e1, @e2 and @e3 while checking that they
- * define a valid triangle.
- */
-void gts_triangle_set (GtsTriangle * triangle, 
-		       GtsEdge * e1, 
-		       GtsEdge * e2,
-		       GtsEdge * e3)
-{
-  g_return_if_fail (e1 != NULL);
-  g_return_if_fail (e2 != NULL);
-  g_return_if_fail (e3 != NULL);
-  g_return_if_fail (e1 != e2 && e1 != e3 && e2 != e3);
-
-  triangle->e1 = e1;
-  triangle->e2 = e2;
-  triangle->e3 = e3;
-
-  if (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e2)->v1)
-    g_return_if_fail (gts_segment_connect (GTS_SEGMENT (e3), 
-					   GTS_SEGMENT (e1)->v2, 
-					   GTS_SEGMENT (e2)->v2));
-  else if (GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v1)
-    g_return_if_fail (gts_segment_connect (GTS_SEGMENT (e3), 
-					   GTS_SEGMENT (e1)->v1, 
-					   GTS_SEGMENT (e2)->v2));
-  else if (GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v2)
-    g_return_if_fail (gts_segment_connect (GTS_SEGMENT (e3), 
-					   GTS_SEGMENT (e1)->v1, 
-					   GTS_SEGMENT (e2)->v1));
-  else if (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e2)->v2)
-    g_return_if_fail (gts_segment_connect (GTS_SEGMENT (e3), 
-					   GTS_SEGMENT (e1)->v2, 
-					   GTS_SEGMENT (e2)->v1));
-  else
-    g_assert_not_reached ();
-
-  e1->triangles = g_slist_prepend (e1->triangles, triangle);
-  e2->triangles = g_slist_prepend (e2->triangles, triangle);
-  e3->triangles = g_slist_prepend (e3->triangles, triangle);
-}
-
-/**
- * gts_triangle_new:
- * @klass: a #GtsTriangleClass.
- * @e1: a #GtsEdge.
- * @e2: another #GtsEdge touching @e1.
- * @e3: another #GtsEdge touching both @e1 and @e2.
- *
- * Returns: a new #GtsTriangle having @e1, @e2 and @e3 as edges.
- */
-GtsTriangle * gts_triangle_new (GtsTriangleClass * klass,
-				GtsEdge * e1,
-				GtsEdge * e2,
-				GtsEdge * e3)
-{
-  GtsTriangle * t;
-
-  t = GTS_TRIANGLE (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  gts_triangle_set (t, e1, e2, e3);
-  
-  return t;
-}
-
-/**
- * gts_triangle_vertex_opposite:
- * @t: a #GtsTriangle.
- * @e: a #GtsEdge used by @t.
- *
- * This function fails if @e is not an edge of @t.
- * 
- * Returns: a #GtsVertex, vertex of @t which does not belong to @e.
- */
-GtsVertex * gts_triangle_vertex_opposite (GtsTriangle * t, GtsEdge * e)
-{
-  g_return_val_if_fail (t != NULL, NULL);
-  g_return_val_if_fail (e != NULL, NULL);
-
-  if (t->e1 == e) {
-    GtsVertex * v = GTS_SEGMENT (t->e2)->v1;
-    if (v != GTS_SEGMENT (e)->v1 && v != GTS_SEGMENT (e)->v2)
-      return v;
-    return GTS_SEGMENT (t->e2)->v2;
-  }
-  if (t->e2 == e) {
-    GtsVertex * v = GTS_SEGMENT (t->e1)->v1;
-    if (v != GTS_SEGMENT (e)->v1 && v != GTS_SEGMENT (e)->v2)
-      return v;
-    return GTS_SEGMENT (t->e1)->v2;
-  }
-  if (t->e3 == e) {
-    GtsVertex * v = GTS_SEGMENT (t->e2)->v1;
-    if (v != GTS_SEGMENT (e)->v1 && v != GTS_SEGMENT (e)->v2)
-      return v;
-    return GTS_SEGMENT (t->e2)->v2;
-  }
-  g_assert_not_reached ();
-  return NULL;
-}
-
-/**
- * gts_triangle_edge_opposite:
- * @t: a #GtsTriangle.
- * @v: a #GtsVertex of @t.
- *
- * Returns: the edge of @t opposite @v or %NULL if @v is not a vertice of @t.
- */
-GtsEdge * gts_triangle_edge_opposite (GtsTriangle * t, GtsVertex * v)
-{
-  GtsSegment * s1, * s2, * s3;
-
-  g_return_val_if_fail (t != NULL, NULL);
-  g_return_val_if_fail (v != NULL, NULL);
-
-  s1 = GTS_SEGMENT (t->e1);
-  s2 = GTS_SEGMENT (t->e2);
-
-  if (s1->v1 != v && s1->v2 != v) {
-    if (s2->v1 != v && s2->v2 != v)
-      return NULL;
-    return t->e1;
-  }
-  if (s2->v1 != v && s2->v2 != v)
-    return t->e2;
-  s3 = GTS_SEGMENT (t->e3);
-  g_assert (s3->v1 != v && s3->v2 != v);
-  return t->e3;
-}
-
-/**
- * gts_triangles_angle:
- * @t1: a #GtsTriangle.
- * @t2: a #GtsTriangle.
- *
- * Returns: the value (in radians) of the angle between @t1 and @t2.
- */
-gdouble gts_triangles_angle (GtsTriangle * t1,
-			     GtsTriangle * t2)
-{
-  gdouble nx1, ny1, nz1, nx2, ny2, nz2;
-  gdouble pvx, pvy, pvz;
-  gdouble theta;
-
-  g_return_val_if_fail (t1 != NULL && t2 != NULL, 0.0);
-
-  gts_triangle_normal (t1, &nx1, &ny1, &nz1);
-  gts_triangle_normal (t2, &nx2, &ny2, &nz2);
-
-  pvx = ny1*nz2 - nz1*ny2;
-  pvy = nz1*nx2 - nx1*nz2;
-  pvz = nx1*ny2 - ny1*nx2;
-
-  theta = atan2 (sqrt (pvx*pvx + pvy*pvy + pvz*pvz), 
-		 nx1*nx2 + ny1*ny2 + nz1*nz2) - M_PI;
-  return theta < - M_PI ? theta + 2.*M_PI : theta;
-}
-
-/**
- * gts_triangles_are_compatible:
- * @t1: a #GtsTriangle.
- * @t2: a #GtsTriangle.
- * @e: a #GtsEdge used by both @t1 and @t2.
- *
- * Checks if @t1 and @t2 have compatible orientations i.e. if @t1 and
- * @t2 can be part of the same surface without conflict in the surface
- * normal orientation.
- *
- * Returns: %TRUE if @t1 and @t2 are compatible, %FALSE otherwise.
- */
-gboolean gts_triangles_are_compatible (GtsTriangle * t1, 
-				       GtsTriangle * t2,
-				       GtsEdge * e)
-{
-  GtsEdge * e1 = NULL, * e2 = NULL;
-
-  g_return_val_if_fail (t1 != NULL, FALSE);
-  g_return_val_if_fail (t2 != NULL, FALSE);
-  g_return_val_if_fail (e != NULL, FALSE);
-
-  if (t1->e1 == e) e1 = t1->e2;
-  else if (t1->e2 == e) e1 = t1->e3;
-  else if (t1->e3 == e) e1 = t1->e1;
-  else
-    g_assert_not_reached ();
-  if (t2->e1 == e) e2 = t2->e2;
-  else if (t2->e2 == e) e2 = t2->e3;
-  else if (t2->e3 == e) e2 = t2->e1;
-  else
-    g_assert_not_reached ();
-  if (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e2)->v1 || 
-      GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e2)->v2 || 
-      GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v1 || 
-      GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v2)
-    return FALSE;
-  return TRUE;
-}
-
-/**
- * gts_triangle_area:
- * @t: a #GtsTriangle.
- *
- * Returns: the area of the triangle @t.
- */
-gdouble gts_triangle_area (GtsTriangle * t)
-{
-  gdouble x, y, z;
-  
-  g_return_val_if_fail (t != NULL, 0.0);
-  
-  gts_triangle_normal (t, &x, &y, &z);
-  
-  return sqrt (x*x + y*y + z*z)/2.;
-}
-
-/**
- * gts_triangle_perimeter:
- * @t: a #GtsTriangle.
- *
- * Returns: the perimeter of the triangle @t.
- */
-gdouble gts_triangle_perimeter (GtsTriangle * t)
-{
-  GtsVertex * v;
-
-  g_return_val_if_fail (t != NULL, 0.0);
-
-  v = gts_triangle_vertex (t);
-  return 
-    gts_point_distance (GTS_POINT (GTS_SEGMENT (t->e1)->v1), 
-			GTS_POINT (GTS_SEGMENT (t->e1)->v2)) +
-    gts_point_distance (GTS_POINT (GTS_SEGMENT (t->e1)->v1), 
-			GTS_POINT (v)) +
-    gts_point_distance (GTS_POINT (GTS_SEGMENT (t->e1)->v2), 
-			GTS_POINT (v));
-}
-
-/* perimeter of the equilateral triangle of area unity */
-#define GOLDEN_PERIMETER 4.5590141139 
-
-/**
- * gts_triangle_quality:
- * @t: a #GtsTriangle.
- *
- * The quality of a triangle is defined as the ratio of the square
- * root of its surface area to its perimeter relative to this same
- * ratio for an equilateral triangle with the same area. The quality
- * is then one for an equilateral triangle and tends to zero for a
- * very stretched triangle.
- *
- * Returns: the quality of the triangle @t.
- */
-gdouble gts_triangle_quality (GtsTriangle * t)
-{
-  gdouble perimeter;
-
-  g_return_val_if_fail (t != NULL, 0.0);
-
-  perimeter = gts_triangle_perimeter (t);
-  return perimeter > 0.0 ?
-    GOLDEN_PERIMETER*sqrt (gts_triangle_area (t))/perimeter :
-    0.0;
-}
-
-/**
- * gts_triangle_normal:
- * @t: a #GtsTriangle.
- * @x: the x coordinate of the normal.
- * @y: the y coordinate of the normal.
- * @z: the z coordinate of the normal.
- *
- * Computes the coordinates of the oriented normal of @t as the
- * cross-product of two edges, using the left-hand rule. The normal is
- * not normalized.  If this triangle is part of a closed and oriented
- * surface, the normal points to the outside of the surface.  
- */
-void gts_triangle_normal (GtsTriangle * t, 
-			  gdouble * x, 
-			  gdouble * y, 
-			  gdouble * z)
-{
-  GtsVertex * v1, * v2 = NULL, * v3 = NULL;
-  GtsPoint * p1, * p2, * p3;
-  gdouble x1, y1, z1, x2, y2, z2;
-
-  g_return_if_fail (t != NULL);
-
-  v1 = GTS_SEGMENT (t->e1)->v1;
-  if (GTS_SEGMENT (t->e1)->v1 == GTS_SEGMENT (t->e2)->v1) {
-    v2 = GTS_SEGMENT (t->e2)->v2;
-    v3 = GTS_SEGMENT (t->e1)->v2;
-  }
-  else if (GTS_SEGMENT (t->e1)->v2 == GTS_SEGMENT (t->e2)->v2) {
-    v2 = GTS_SEGMENT (t->e1)->v2;
-    v3 = GTS_SEGMENT (t->e2)->v1;
-  }
-  else if (GTS_SEGMENT (t->e1)->v1 == GTS_SEGMENT (t->e2)->v2) {
-    v2 = GTS_SEGMENT (t->e2)->v1;
-    v3 = GTS_SEGMENT (t->e1)->v2;
-  }
-  else if (GTS_SEGMENT (t->e1)->v2 == GTS_SEGMENT (t->e2)->v1) {
-    v2 = GTS_SEGMENT (t->e1)->v2;
-    v3 = GTS_SEGMENT (t->e2)->v2;
-  }
-  else {
-    fprintf (stderr, "t: %p t->e1: %p t->e2: %p t->e3: %p t->e1->v1: %p t->e1->v2: %p t->e2->v1: %p t->e2->v2: %p t->e3->v1: %p t->e3->v2: %p\n",
-	 t, t->e1, t->e2, 
-	 t->e3, GTS_SEGMENT (t->e1)->v1, GTS_SEGMENT (t->e1)->v2, 
-	 GTS_SEGMENT (t->e2)->v1, GTS_SEGMENT (t->e2)->v2, 
-	 GTS_SEGMENT (t->e3)->v1, GTS_SEGMENT (t->e3)->v2);
-    g_assert_not_reached ();
-  }
-
-  p1 = GTS_POINT (v1);
-  p2 = GTS_POINT (v2);
-  p3 = GTS_POINT (v3);
-
-  x1 = p2->x - p1->x;
-  y1 = p2->y - p1->y;
-  z1 = p2->z - p1->z;
-
-  x2 = p3->x - p1->x;
-  y2 = p3->y - p1->y;
-  z2 = p3->z - p1->z;
-
-  *x = y1*z2 - z1*y2;
-  *y = z1*x2 - x1*z2;
-  *z = x1*y2 - y1*x2;
-}
-
-/**
- * gts_triangle_orientation:
- * @t: a #GtsTriangle.
- * 
- * Checks for the orientation of the plane (x,y) projection of a
- * triangle. See gts_point_orientation() for details. This function
- * is geometrically robust.
- *
- * Returns: a number depending on the orientation of the vertices of @t.
- */
-gdouble gts_triangle_orientation (GtsTriangle * t)
-{
-  GtsVertex * v1, * v2 = NULL, * v3 = NULL;
-
-  g_return_val_if_fail (t != NULL, 0.0);
-
-  v1 = GTS_SEGMENT (t->e1)->v1;
-  if (GTS_SEGMENT (t->e1)->v1 == GTS_SEGMENT (t->e2)->v1) {
-    v2 = GTS_SEGMENT (t->e2)->v2;
-    v3 = GTS_SEGMENT (t->e1)->v2;
-  }
-  else if (GTS_SEGMENT (t->e1)->v2 == GTS_SEGMENT (t->e2)->v2) {
-    v2 = GTS_SEGMENT (t->e1)->v2;
-    v3 = GTS_SEGMENT (t->e2)->v1;
-  }
-  else if (GTS_SEGMENT (t->e1)->v1 == GTS_SEGMENT (t->e2)->v2) {
-    v2 = GTS_SEGMENT (t->e2)->v1;
-    v3 = GTS_SEGMENT (t->e1)->v2;
-  }
-  else if (GTS_SEGMENT (t->e1)->v2 == GTS_SEGMENT (t->e2)->v1) {
-    v2 = GTS_SEGMENT (t->e1)->v2;
-    v3 = GTS_SEGMENT (t->e2)->v2;
-  }
-  else
-    g_assert_not_reached ();
-  return gts_point_orientation (GTS_POINT (v1), 
-				GTS_POINT (v2), 
-				GTS_POINT (v3));
-}
-
-/**
- * gts_triangle_revert:
- * @t: a #GtsTriangle.
- * 
- * Changes the orientation of triangle @t, turning it inside out.
- */
-void gts_triangle_revert (GtsTriangle * t)
-{
-  GtsEdge * e;
-
-  g_return_if_fail (t != NULL);
-
-  e = t->e1;
-  t->e1 = t->e2;
-  t->e2 = e;
-}
-
-/**
- * gts_triangles_from_edges:
- * @edges: a list of #GtsEdge.
- *
- * Builds a list of unique triangles which have one of their edges in @edges.
- * 
- * Returns: the list of triangles.
- */
-GSList * gts_triangles_from_edges (GSList * edges)
-{
-  GHashTable * hash;
-  GSList * triangles = NULL, * i;
-
-  hash = g_hash_table_new (NULL, NULL);
-  i = edges;
-  while (i) {
-    GSList * j = GTS_EDGE (i->data)->triangles;
-    while (j) {
-      GtsTriangle * t = j->data;
-      if (g_hash_table_lookup (hash, t) == NULL) {
-	triangles = g_slist_prepend (triangles, t);
-	g_hash_table_insert (hash, t, i);
-      }
-      j = j->next;
-    }
-    i = i->next;
-  }
-  g_hash_table_destroy (hash);
-
-  return triangles;
-}
-
-/**
- * gts_triangle_vertices_edges:
- * @t: a #GtsTriangle.
- * @e: a #GtsEdge belonging to the edges of @t or %NULL.
- * @v1: a #GtsVertex used by @t.
- * @v2: a #GtsVertex used by @t.
- * @v3: a #GtsVertex used by @t.
- * @e1: a #GtsEdge used by @t.
- * @e2: a #GtsEdge used by @t.
- * @e3: a #GtsEdge used by @t.
- *
- * Given @t and @e, returns @v1, @v2, @v3, @e1, @e2 and @e3. @e1
- * has @v1 and @v2 as vertices, @e2 has @v2 and @v3 as vertices
- * and @e3 has @v3 and @v1 as vertices. @v1, @v2 and @v3 respects
- * the orientation of @t. If @e is not NULL, @e1 and @e are
- * identical.
- */
-void gts_triangle_vertices_edges (GtsTriangle * t, 
-				  GtsEdge * e,
-				  GtsVertex ** v1, 
-				  GtsVertex ** v2, 
-				  GtsVertex ** v3,
-				  GtsEdge ** e1,
-				  GtsEdge ** e2,
-				  GtsEdge ** e3)
-{
-  GtsEdge * ee1, * ee2;
-
-  g_return_if_fail (t != NULL);
-  
-  if (e == t->e1 || e == NULL) {
-    *e1 = ee1 = t->e1; *e2 = ee2 = t->e2; *e3 = t->e3;    
-  }
-  else if (e == t->e2) {
-    *e1 = ee1 = e; *e2 = ee2 = t->e3; *e3 = t->e1;
-  }
-  else if (e == t->e3) {
-    *e1 = ee1 = e; *e2 = ee2 = t->e1; *e3 = t->e2;
-  }
-  else {
-    g_assert_not_reached ();
-    ee1 = ee2 = NULL; /* to avoid complaints from the compiler */
-  }
-  if (GTS_SEGMENT (ee1)->v2 == GTS_SEGMENT (ee2)->v1) {
-    *v1 = GTS_SEGMENT (ee1)->v1; 
-    *v2 = GTS_SEGMENT (ee1)->v2; 
-    *v3 = GTS_SEGMENT (ee2)->v2;
-  }
-  else if (GTS_SEGMENT (ee1)->v2 == GTS_SEGMENT (ee2)->v2) {
-    *v1 = GTS_SEGMENT (ee1)->v1; 
-    *v2 = GTS_SEGMENT (ee1)->v2; 
-    *v3 = GTS_SEGMENT (ee2)->v1;
-  }
-  else if (GTS_SEGMENT (ee1)->v1 == GTS_SEGMENT (ee2)->v1) {
-    *v1 = GTS_SEGMENT (ee1)->v2; 
-    *v2 = GTS_SEGMENT (ee1)->v1; 
-    *v3 = GTS_SEGMENT (ee2)->v2;
-  }
-  else if (GTS_SEGMENT (ee1)->v1 == GTS_SEGMENT (ee2)->v2) {
-    *v1 = GTS_SEGMENT (ee1)->v2; 
-    *v2 = GTS_SEGMENT (ee1)->v1; 
-    *v3 = GTS_SEGMENT (ee2)->v1;
-  }
-  else
-    g_assert_not_reached ();
-}
-
-/* sqrt(3) */
-#define SQRT3 1.73205080757
-
-/**
- * gts_triangle_enclosing:
- * @klass: the class of the new triangle.
- * @points: a list of #GtsPoint.
- * @scale: a scaling factor (must be larger than one).
- * 
- * Builds a new triangle (including new vertices and edges) enclosing
- * the plane projection of all the points in @points. This triangle is
- * equilateral and encloses a rectangle defined by the maximum and
- * minimum x and y coordinates of the points. @scale is an homothetic
- * scaling factor. If equal to one, the triangle encloses exactly the
- * enclosing rectangle.
- * 
- * Returns: a new #GtsTriangle.  
- */
-GtsTriangle * gts_triangle_enclosing (GtsTriangleClass * klass,
-				      GSList * points, gdouble scale)
-{
-  gdouble xmax, xmin, ymax, ymin;
-  gdouble xo, yo, r;
-  GtsVertex * v1, * v2, * v3;
-  GtsEdge * e1, * e2, * e3;
-
-  if (points == NULL)
-    return NULL;
-  
-  xmax = xmin = GTS_POINT (points->data)->x;
-  ymax = ymin = GTS_POINT (points->data)->y;
-  points = points->next;
-  while (points) {
-    GtsPoint * p = points->data;
-    if (p->x > xmax) xmax = p->x;
-    else if (p->x < xmin) xmin = p->x;
-    if (p->y > ymax) ymax = p->y;
-    else if (p->y < ymin) ymin = p->y;    
-    points = points->next;
-  }
-  xo = (xmax + xmin)/2.;
-  yo = (ymax + ymin)/2.;
-  r = scale*sqrt((xmax - xo)*(xmax - xo) + (ymax - yo)*(ymax - yo));
-  if (r == 0.0) r = scale;
-  v1 = gts_vertex_new (gts_vertex_class (),
-		       xo + r*SQRT3, yo - r, 0.0);
-  v2 = gts_vertex_new (gts_vertex_class (),
-		       xo, yo + 2.*r, 0.0);
-  v3 = gts_vertex_new (gts_vertex_class (),
-		       xo - r*SQRT3, yo - r, 0.0);
-  e1 = gts_edge_new (gts_edge_class (), v1, v2);
-  e2 = gts_edge_new (gts_edge_class (), v2, v3);
-  e3 = gts_edge_new (gts_edge_class (), v3, v1);
-  return gts_triangle_new (gts_triangle_class (), e1, e2, e3);
-}
-
-/**
- * gts_triangle_neighbor_number:
- * @t: a #GtsTriangle.
- *
- * Returns: the number of triangles neighbors of @t.
- */
-guint gts_triangle_neighbor_number (GtsTriangle * t)
-{
-  GSList * i;
-  guint nn = 0;
-  GtsEdge * ee[4], ** e = ee;
-  
-  g_return_val_if_fail (t != NULL, 0);
-
-  ee[0] = t->e1; ee[1] = t->e2; ee[2] = t->e3; ee[3] = NULL;
-  while (*e) {
-    i = (*e++)->triangles;
-    while (i) {
-      GtsTriangle * t1 = i->data;
-      if (t1 != t)
-	nn++;
-      i = i->next;
-    }
-  }
-  return nn;
-}
-
-/**
- * gts_triangle_neighbors:
- * @t: a #GtsTriangle.
- *
- * Returns: a list of #GtsTriangle neighbors of @t.
- */
-GSList * gts_triangle_neighbors (GtsTriangle * t)
-{
-  GSList * i, * list = NULL;
-  GtsEdge * ee[4], ** e = ee;
-  
-  g_return_val_if_fail (t != NULL, NULL);
-
-  ee[0] = t->e1; ee[1] = t->e2; ee[2] = t->e3; ee[3] = NULL;
-  while (*e) {
-    i = (*e++)->triangles;
-    while (i) {
-      GtsTriangle * t1 = i->data;
-      if (t1 != t)
-	list = g_slist_prepend (list, t1);
-      i = i->next;
-    }
-  }
-  return list;
-}
-
-/**
- * gts_triangles_common_edge:
- * @t1: a #GtsTriangle.
- * @t2: a #GtsTriangle.
- *
- * Returns: a #GtsEdge common to both @t1 and @t2 or %NULL if @t1 and @t2
- * do not share any edge.
- */
-GtsEdge * gts_triangles_common_edge (GtsTriangle * t1,
-				     GtsTriangle * t2)
-{
-  g_return_val_if_fail (t1 != NULL, NULL);
-  g_return_val_if_fail (t2 != NULL, NULL);
-
-  if (t1->e1 == t2->e1 || t1->e1 == t2->e2 || t1->e1 == t2->e3)
-    return t1->e1;
-  if (t1->e2 == t2->e1 || t1->e2 == t2->e2 || t1->e2 == t2->e3)
-    return t1->e2;
-  if (t1->e3 == t2->e1 || t1->e3 == t2->e2 || t1->e3 == t2->e3)
-    return t1->e3;
-  return NULL;
-}
-
-/**
- * gts_triangle_is_duplicate:
- * @t: a #GtsTriangle.
- *
- * Returns: a #GtsTriangle different from @t but sharing all its edges 
- * with @t or %NULL if there is none.
- */
-GtsTriangle * gts_triangle_is_duplicate (GtsTriangle * t)
-{
-  GSList * i;
-  GtsEdge * e2, * e3;
-
-  g_return_val_if_fail (t != NULL, NULL);
-
-  e2 = t->e2;
-  e3 = t->e3;
-  i = t->e1->triangles;
-  while (i) {
-    GtsTriangle * t1 = i->data;
-    if (t1 != t && 
-	(t1->e1 == e2 || t1->e2 == e2 || t1->e3 == e2) &&
-	(t1->e1 == e3 || t1->e2 == e3 || t1->e3 == e3))
-      return t1;
-    i = i->next;
-  }
-  
-  return NULL;
-}
-
-/**
- * gts_triangle_use_edges:
- * @e1: a #GtsEdge.
- * @e2: a #GtsEdge.
- * @e3: a #GtsEdge.
- *
- * Returns: a #GtsTriangle having @e1, @e2 and @e3 as edges or %NULL if @e1,
- * @e2 and @e3 are not part of any triangle.
- */
-GtsTriangle * gts_triangle_use_edges (GtsEdge * e1,
-				      GtsEdge * e2,
-				      GtsEdge * e3)
-{
-  GSList * i;
-  
-  g_return_val_if_fail (e1 != NULL, NULL);
-  g_return_val_if_fail (e2 != NULL, NULL);
-  g_return_val_if_fail (e3 != NULL, NULL);
-
-  i = e1->triangles;
-  while (i) {
-    GtsTriangle * t = i->data;
-    if ((t->e1 == e2 && (t->e2 == e3 || t->e3 == e3)) ||
-	(t->e2 == e2 && (t->e1 == e3 || t->e3 == e3)) ||
-	(t->e3 == e2 && (t->e1 == e3 || t->e2 == e3)))
-      return t;
-    i = i->next;
-  }
-  
-  return NULL;
-}
-
-/**
- * gts_triangle_is_ok:
- * @t: a #GtsTriangle.
- *
- * Returns: %TRUE if @t is a non-degenerate, non-duplicate triangle,
- * %FALSE otherwise.
- */
-gboolean gts_triangle_is_ok (GtsTriangle * t)
-{
-  g_return_val_if_fail (t != NULL, FALSE);
-  g_return_val_if_fail (t->e1 != NULL, FALSE);
-  g_return_val_if_fail (t->e2 != NULL, FALSE);
-  g_return_val_if_fail (t->e3 != NULL, FALSE);
-  g_return_val_if_fail (t->e1 != t->e2 && t->e1 != t->e3 && t->e2 != t->e3, 
-			FALSE);
-  g_return_val_if_fail (gts_segments_touch (GTS_SEGMENT (t->e1), 
-					    GTS_SEGMENT (t->e2)),
-			FALSE);
-  g_return_val_if_fail (gts_segments_touch (GTS_SEGMENT (t->e1), 
-					    GTS_SEGMENT (t->e3)), 
-			FALSE);
-  g_return_val_if_fail (gts_segments_touch (GTS_SEGMENT (t->e2), 
-					    GTS_SEGMENT (t->e3)), 
-			FALSE);
-  g_return_val_if_fail (GTS_SEGMENT (t->e1)->v1 != GTS_SEGMENT (t->e1)->v2, 
-			FALSE);
-  g_return_val_if_fail (GTS_SEGMENT (t->e2)->v1 != GTS_SEGMENT (t->e2)->v2, 
-			FALSE);
-  g_return_val_if_fail (GTS_SEGMENT (t->e3)->v1 != GTS_SEGMENT (t->e3)->v2, 
-			FALSE);
-  g_return_val_if_fail (GTS_OBJECT (t)->reserved == NULL, FALSE);
-  g_return_val_if_fail (!gts_triangle_is_duplicate (t), FALSE);
-  return TRUE;
-}
-
-/**
- * gts_triangle_vertices:
- * @t: a #GtsTriangle.
- * @v1: a pointer on a #GtsVertex.
- * @v2: a pointer on a #GtsVertex.
- * @v3: a pointer on a #GtsVertex.
- *
- * Fills @v1, @v2 and @v3 with the oriented set of vertices, summits of @t.
- */
-void gts_triangle_vertices (GtsTriangle * t,
-			    GtsVertex ** v1, GtsVertex ** v2, GtsVertex ** v3)
-{
-  GtsSegment * e1, * e2;
-
-  g_return_if_fail (t != NULL);
-  g_return_if_fail (v1 != NULL && v2 != NULL && v3 != NULL);
-
-  e1 = GTS_SEGMENT (t->e1);
-  e2 = GTS_SEGMENT (t->e2);
-
-  if (GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v1) {
-    *v1 = GTS_SEGMENT (e1)->v1; 
-    *v2 = GTS_SEGMENT (e1)->v2; 
-    *v3 = GTS_SEGMENT (e2)->v2;
-  }
-  else if (GTS_SEGMENT (e1)->v2 == GTS_SEGMENT (e2)->v2) {
-    *v1 = GTS_SEGMENT (e1)->v1; 
-    *v2 = GTS_SEGMENT (e1)->v2; 
-    *v3 = GTS_SEGMENT (e2)->v1;
-  }
-  else if (GTS_SEGMENT (e1)->v1 == GTS_SEGMENT (e2)->v1) {
-    *v1 = GTS_SEGMENT (e1)->v2; 
-    *v2 = GTS_SEGMENT (e1)->v1; 
-    *v3 = GTS_SEGMENT (e2)->v2;
-  }
-  else {
-    *v1 = GTS_SEGMENT (e1)->v2; 
-    *v2 = GTS_SEGMENT (e1)->v1; 
-    *v3 = GTS_SEGMENT (e2)->v1;
-  }
-}
-
-/**
- * gts_triangle_circumcircle_center:
- * @t: a #GtsTriangle.
- * @point_class: a #GtsPointClass.
- *
- * Returns: a new #GtsPoint, center of the circumscribing circle of @t or
- * %NULL if the circumscribing circle is not defined.
- */
-GtsPoint * gts_triangle_circumcircle_center (GtsTriangle * t,
-					     GtsPointClass * point_class)
-{
-  GtsVertex * v1, * v2, * v3;
-  gdouble xa, ya, xb, yb, xc, yc;
-  gdouble xd, yd, xe, ye;
-  gdouble xad, yad, xae, yae;
-  gdouble det;
-  
-  g_return_val_if_fail (t != NULL, NULL);
-  g_return_val_if_fail (point_class != NULL, NULL);
-
-  gts_triangle_vertices (t, &v1, &v2, &v3);
-
-  xa = GTS_POINT (v1)->x; ya = GTS_POINT (v1)->y;
-  xb = GTS_POINT (v2)->x; yb = GTS_POINT (v2)->y;
-  xc = GTS_POINT (v3)->x; yc = GTS_POINT (v3)->y;
-  xd = (xa + xb)/2.; yd = (ya + yb)/2.;
-  xe = (xa + xc)/2.; ye = (ya + yc)/2.;
-  xad = xd - xa; yad = yd - ya;
-  xae = xe - xa; yae = ye - ya;
-  det = xad*yae - xae*yad;
-  if (det == 0.)
-    return NULL;
-  return gts_point_new (point_class,
-			(yae*yad*(yd - ye) + xad*yae*xd - xae*yad*xe)/det,
-			-(xae*xad*(xd - xe) + yad*xae*yd - yae*xad*ye)/det,
-			0.);
-}
-
-/* square of the maximum area ratio admissible */
-#define AREA_RATIO_MAX2 1e8
-
-static gboolean points_are_folded (GtsPoint * A,
-				   GtsPoint * B,
-				   GtsPoint * C,
-				   GtsPoint * D,
-				   gdouble max)
-{
-  GtsVector AB, AC, AD;
-  GtsVector n1, n2;
-  gdouble nn1, nn2, n1n2;
-
-  gts_vector_init (AB, A, B);
-  gts_vector_init (AC, A, C);
-  gts_vector_init (AD, A, D);
-  gts_vector_cross (n1, AB, AC);
-  gts_vector_cross (n2, AD, AB);
-
-  nn1 = gts_vector_scalar (n1, n1);
-  nn2 = gts_vector_scalar (n2, n2);
-  if (nn1 >= AREA_RATIO_MAX2*nn2 || nn2 >= AREA_RATIO_MAX2*nn1)
-    return TRUE;
-  n1n2 = gts_vector_scalar (n1, n2);
-  if (n1n2 > 0.)
-    return FALSE;
-  if (n1n2*n1n2/(nn1*nn2) > max)
-    return TRUE;
-  return FALSE;
-}
-
-static GtsVertex * triangle_use_vertices (GtsTriangle * t,
-					  GtsVertex * A, 
-					  GtsVertex * B)
-{
-  GtsVertex 
-    * v1 = GTS_SEGMENT (t->e1)->v1, 
-    * v2 = GTS_SEGMENT (t->e1)->v2, 
-    * v3 = gts_triangle_vertex (t);
-
-  if (v1 == A) {
-    if (v2 == B)
-      return v3;
-    g_assert (v3 == B);
-    return v2;
-  }
-  if (v2 == A) {
-    if (v1 == B)
-      return v3;
-    g_assert (v3 == B);
-    return v1;
-  }
-  if (v3 == A) {
-    if (v1 == B)
-      return v2;
-    g_assert (v2 == B);
-    return v1;
-  }
-  g_assert_not_reached ();
-  return NULL;
-}
-
-/**
- * gts_triangles_are_folded:
- * @triangles: a list of #GtsTriangle.
- * @A: a #GtsVertex.
- * @B: another #GtsVertex.
- * @max: the maximum value of the square of the cosine of the angle between
- * two triangles.
- *
- * Given a list of triangles sharing @A and @B as vertices, checks if any
- * two triangles in the list make an angle larger than a given value defined
- * by @max.
- * 
- * Returns: %TRUE if any pair of triangles in @triangles makes an angle larger 
- * than the maximum value, %FALSE otherwise.
- */
-gboolean gts_triangles_are_folded (GSList * triangles,
-				   GtsVertex * A, GtsVertex * B,
-				   gdouble max)
-{
-  GSList * i;
-
-  g_return_val_if_fail (A != NULL, TRUE);
-  g_return_val_if_fail (B != NULL, TRUE);
-
-  i = triangles;
-  while (i) {
-    GtsVertex * C = triangle_use_vertices (i->data, A, B);
-    GSList * j = i->next;    
-    while (j) {
-      GtsVertex * D = triangle_use_vertices (j->data, A, B);
-      if (points_are_folded (GTS_POINT (A), 
-			     GTS_POINT (B), 
-			     GTS_POINT (C), 
-			     GTS_POINT (D), 
-			     max))
-	return TRUE;
-      j = j->next;
-    }
-    i = i->next;
-  }
-  return FALSE;
-}
-
-/**
- * gts_triangle_is_stabbed:
- * @t: a #GtsTriangle.
- * @p: a #GtsPoint.
- * @orientation: a pointer or %NULL.
- *
- * Returns: one of the vertices of @t, one of the edges of @t or @t if
- * any of these are stabbed by the ray starting at @p (included) and
- * ending at (@p->x, @p->y, +infty), %NULL otherwise. If the ray is
- * contained in the plane of the triangle %NULL is also returned. If
- * @orientation is not %NULL, it is set to the value of the
- * orientation of @p relative to @t (as given by
- * gts_point_orientation_3d()).  
- */
-GtsObject * gts_triangle_is_stabbed (GtsTriangle * t, 
-				     GtsPoint * p,
-				     gdouble * orientation)
-{
-  GtsVertex * v1, * v2, * v3, * inverted = NULL;
-  GtsEdge * e1, * e2, * e3, * tmp;
-  gdouble o, o1, o2, o3;
-
-  g_return_val_if_fail (t != NULL, NULL);
-  g_return_val_if_fail (p != NULL, NULL);
-
-  gts_triangle_vertices_edges (t, NULL, &v1, &v2, &v3, &e1, &e2, &e3);
-  o = gts_point_orientation (GTS_POINT (v1), GTS_POINT (v2), GTS_POINT (v3));
-  if (o == 0.)
-    return NULL;
-  if (o < 0.) {
-    inverted = v1;
-    v1 = v2;
-    v2 = inverted;
-    tmp = e2;
-    e2 = e3;
-    e3 = tmp;
-  }
-  o = gts_point_orientation_3d (GTS_POINT (v1),
-				GTS_POINT (v2), 
-				GTS_POINT (v3), 
-				p);
-  if (o < 0.)
-    return NULL;
-  o1 = gts_point_orientation (GTS_POINT (v1), GTS_POINT (v2), p);
-  if (o1 < 0.)
-    return NULL;
-  o2 = gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), p);
-  if (o2 < 0.)
-    return NULL;
-  o3 = gts_point_orientation (GTS_POINT (v3), GTS_POINT (v1), p);
-  if (o3 < 0.)
-    return NULL;  
-  if (orientation) *orientation = inverted ? -o : o;
-  if (o1 == 0.) {
-    if (o2 == 0.)
-      return GTS_OBJECT (v2);
-    if (o3 == 0.)
-      return GTS_OBJECT (v1);
-    return GTS_OBJECT (e1);
-  }
-  if (o2 == 0.) {
-    if (o3 == 0.)
-      return GTS_OBJECT (v3);
-    return GTS_OBJECT (e2);
-  }
-  if (o3 == 0.)
-    return GTS_OBJECT (e3);
-  return GTS_OBJECT (t);
-}
-
-/**
- * gts_triangle_interpolate_height:
- * @t: a #GtsTriangle.
- * @p: a #GtsPoint.
- *
- * Fills the z-coordinate of point @p belonging to the plane
- * projection of triangle @t with the linearly interpolated value of
- * the z-coordinates of the vertices of @t.
- */
-void gts_triangle_interpolate_height (GtsTriangle * t, GtsPoint * p)
-{
-  GtsPoint * p1, * p2, * p3;
-  gdouble x1, x2, y1, y2, det;
-
-  g_return_if_fail (t != NULL);
-  g_return_if_fail (p != NULL);
-
-  p1 = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
-  p2 = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
-  p3 = GTS_POINT (gts_triangle_vertex (t));
-
-  x1 = p2->x - p1->x;
-  y1 = p2->y - p1->y;
-  x2 = p3->x - p1->x;
-  y2 = p3->y - p1->y;
-  det = x1*y2 - x2*y1;
-  if (det == 0.)
-    p->z = (p1->z + p2->z + p3->z)/3.;
-  else {
-    gdouble x = p->x - p1->x;
-    gdouble y = p->y - p1->y;
-    gdouble a = (x*y2 - y*x2)/det;
-    gdouble b = (y*x1 - x*y1)/det;
-
-    p->z = (1. - a - b)*p1->z + a*p2->z + b*p3->z;
-  }
-}
diff --git a/src/gts/tribox3.c b/src/gts/tribox3.c
deleted file mode 100644
index c0ea778..0000000
--- a/src/gts/tribox3.c
+++ /dev/null
@@ -1,192 +0,0 @@
-/**
- * History:
- * 2004-10-27 Stephane Popinet: changed float to double
- */
-
-/********************************************************/
-/* AABB-triangle overlap test code                      */
-/* by Tomas Akenine-Möller                              */
-/* Function: int triBoxOverlap(float boxcenter[3],      */
-/*          float boxhalfsize[3],float triverts[3][3]); */
-/* History:                                             */
-/*   2001-03-05: released the code in its first version */
-/*   2001-06-18: changed the order of the tests, faster */
-/*                                                      */
-/* Acknowledgement: Many thanks to Pierre Terdiman for  */
-/* suggestions and discussions on how to optimize code. */
-/* Thanks to David Hunt for finding a ">="-bug!         */
-/********************************************************/
-#include <math.h>
-#include <stdio.h>
-
-#define X 0
-#define Y 1
-#define Z 2
-
-#define CROSS(dest,v1,v2) \
-          dest[0]=v1[1]*v2[2]-v1[2]*v2[1]; \
-          dest[1]=v1[2]*v2[0]-v1[0]*v2[2]; \
-          dest[2]=v1[0]*v2[1]-v1[1]*v2[0]; 
-
-#define DOT(v1,v2) (v1[0]*v2[0]+v1[1]*v2[1]+v1[2]*v2[2])
-
-#define SUB(dest,v1,v2) \
-          dest[0]=v1[0]-v2[0]; \
-          dest[1]=v1[1]-v2[1]; \
-          dest[2]=v1[2]-v2[2]; 
-
-#define FINDMINMAX(x0,x1,x2,min,max) \
-  min = max = x0;   \
-  if(x1<min) min=x1;\
-  if(x1>max) max=x1;\
-  if(x2<min) min=x2;\
-  if(x2>max) max=x2;
-
-int planeBoxOverlap(double normal[3], double vert[3], double maxbox[3])	// -NJMP-
-{
-  int q;
-  double vmin[3],vmax[3],v;
-  for(q=X;q<=Z;q++)
-  {
-    v=vert[q];					// -NJMP-
-    if(normal[q]>0.0f)
-    {
-      vmin[q]=-maxbox[q] - v;	// -NJMP-
-      vmax[q]= maxbox[q] - v;	// -NJMP-
-    }
-    else
-    {
-      vmin[q]= maxbox[q] - v;	// -NJMP-
-      vmax[q]=-maxbox[q] - v;	// -NJMP-
-    }
-  }
-  if(DOT(normal,vmin)>0.0f) return 0;	// -NJMP-
-  if(DOT(normal,vmax)>=0.0f) return 1;	// -NJMP-
-  
-  return 0;
-}
-
-
-/*======================== X-tests ========================*/
-#define AXISTEST_X01(a, b, fa, fb)			   \
-	p0 = a*v0[Y] - b*v0[Z];			       	   \
-	p2 = a*v2[Y] - b*v2[Z];			       	   \
-        if(p0<p2) {min=p0; max=p2;} else {min=p2; max=p0;} \
-	rad = fa * boxhalfsize[Y] + fb * boxhalfsize[Z];   \
-	if(min>rad || max<-rad) return 0;
-
-#define AXISTEST_X2(a, b, fa, fb)			   \
-	p0 = a*v0[Y] - b*v0[Z];			           \
-	p1 = a*v1[Y] - b*v1[Z];			       	   \
-        if(p0<p1) {min=p0; max=p1;} else {min=p1; max=p0;} \
-	rad = fa * boxhalfsize[Y] + fb * boxhalfsize[Z];   \
-	if(min>rad || max<-rad) return 0;
-
-/*======================== Y-tests ========================*/
-#define AXISTEST_Y02(a, b, fa, fb)			   \
-	p0 = -a*v0[X] + b*v0[Z];		      	   \
-	p2 = -a*v2[X] + b*v2[Z];	       	       	   \
-        if(p0<p2) {min=p0; max=p2;} else {min=p2; max=p0;} \
-	rad = fa * boxhalfsize[X] + fb * boxhalfsize[Z];   \
-	if(min>rad || max<-rad) return 0;
-
-#define AXISTEST_Y1(a, b, fa, fb)			   \
-	p0 = -a*v0[X] + b*v0[Z];		      	   \
-	p1 = -a*v1[X] + b*v1[Z];	     	       	   \
-        if(p0<p1) {min=p0; max=p1;} else {min=p1; max=p0;} \
-	rad = fa * boxhalfsize[X] + fb * boxhalfsize[Z];   \
-	if(min>rad || max<-rad) return 0;
-
-/*======================== Z-tests ========================*/
-
-#define AXISTEST_Z12(a, b, fa, fb)			   \
-	p1 = a*v1[X] - b*v1[Y];			           \
-	p2 = a*v2[X] - b*v2[Y];			       	   \
-        if(p2<p1) {min=p2; max=p1;} else {min=p1; max=p2;} \
-	rad = fa * boxhalfsize[X] + fb * boxhalfsize[Y];   \
-	if(min>rad || max<-rad) return 0;
-
-#define AXISTEST_Z0(a, b, fa, fb)			   \
-	p0 = a*v0[X] - b*v0[Y];				   \
-	p1 = a*v1[X] - b*v1[Y];			           \
-        if(p0<p1) {min=p0; max=p1;} else {min=p1; max=p0;} \
-	rad = fa * boxhalfsize[X] + fb * boxhalfsize[Y];   \
-	if(min>rad || max<-rad) return 0;
-
-int triBoxOverlap(double boxcenter[3],double boxhalfsize[3],double triverts[3][3])
-{
-
-  /*    use separating axis theorem to test overlap between triangle and box */
-  /*    need to test for overlap in these directions: */
-  /*    1) the {x,y,z}-directions (actually, since we use the AABB of the triangle */
-  /*       we do not even need to test these) */
-  /*    2) normal of the triangle */
-  /*    3) crossproduct(edge from tri, {x,y,z}-directin) */
-  /*       this gives 3x3=9 more tests */
-   double v0[3],v1[3],v2[3];
-//   double axis[3];
-   double min,max,p0,p1,p2,rad,fex,fey,fez;		// -NJMP- "d" local variable removed
-   double normal[3],e0[3],e1[3],e2[3];
-
-   /* This is the fastest branch on Sun */
-   /* move everything so that the boxcenter is in (0,0,0) */
-   SUB(v0,triverts[0],boxcenter);
-   SUB(v1,triverts[1],boxcenter);
-   SUB(v2,triverts[2],boxcenter);
-
-   /* compute triangle edges */
-   SUB(e0,v1,v0);      /* tri edge 0 */
-   SUB(e1,v2,v1);      /* tri edge 1 */
-   SUB(e2,v0,v2);      /* tri edge 2 */
-
-   /* Bullet 3:  */
-   /*  test the 9 tests first (this was faster) */
-   fex = fabsf(e0[X]);
-   fey = fabsf(e0[Y]);
-   fez = fabsf(e0[Z]);
-   AXISTEST_X01(e0[Z], e0[Y], fez, fey);
-   AXISTEST_Y02(e0[Z], e0[X], fez, fex);
-   AXISTEST_Z12(e0[Y], e0[X], fey, fex);
-
-   fex = fabsf(e1[X]);
-   fey = fabsf(e1[Y]);
-   fez = fabsf(e1[Z]);
-   AXISTEST_X01(e1[Z], e1[Y], fez, fey);
-   AXISTEST_Y02(e1[Z], e1[X], fez, fex);
-   AXISTEST_Z0(e1[Y], e1[X], fey, fex);
-
-   fex = fabsf(e2[X]);
-   fey = fabsf(e2[Y]);
-   fez = fabsf(e2[Z]);
-   AXISTEST_X2(e2[Z], e2[Y], fez, fey);
-   AXISTEST_Y1(e2[Z], e2[X], fez, fex);
-   AXISTEST_Z12(e2[Y], e2[X], fey, fex);
-
-   /* Bullet 1: */
-   /*  first test overlap in the {x,y,z}-directions */
-   /*  find min, max of the triangle each direction, and test for overlap in */
-   /*  that direction -- this is equivalent to testing a minimal AABB around */
-   /*  the triangle against the AABB */
-
-   /* test in X-direction */
-   FINDMINMAX(v0[X],v1[X],v2[X],min,max);
-   if(min>boxhalfsize[X] || max<-boxhalfsize[X]) return 0;
-
-   /* test in Y-direction */
-   FINDMINMAX(v0[Y],v1[Y],v2[Y],min,max);
-   if(min>boxhalfsize[Y] || max<-boxhalfsize[Y]) return 0;
-
-   /* test in Z-direction */
-   FINDMINMAX(v0[Z],v1[Z],v2[Z],min,max);
-   if(min>boxhalfsize[Z] || max<-boxhalfsize[Z]) return 0;
-
-   /* Bullet 2: */
-   /*  test if the box intersects the plane of the triangle */
-   /*  compute plane equation of triangle: normal*x+d=0 */
-   CROSS(normal,e0,e1);
-   // -NJMP- (line removed here)
-   if(!planeBoxOverlap(normal,v0,boxhalfsize)) return 0;	// -NJMP-
-
-   return 1;   /* box and triangle overlaps */
-}
-
diff --git a/src/gts/vertex.c b/src/gts/vertex.c
deleted file mode 100644
index d312869..0000000
--- a/src/gts/vertex.c
+++ /dev/null
@@ -1,780 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include <math.h>
-#include "gts.h"
-
-gboolean gts_allow_floating_vertices = FALSE;
-
-static void vertex_destroy (GtsObject * object)
-{
-  GtsVertex * vertex = GTS_VERTEX (object);
-  GSList * i;
-
-  i = vertex->segments;
-  while (i) {
-    GTS_OBJECT_SET_FLAGS (i->data, GTS_DESTROYED);
-    i = i->next;
-  }
-  i = vertex->segments;
-  while (i) {
-    GSList * next = i->next;
-    gts_object_destroy (i->data);
-    i = next;
-  }
-  g_assert (vertex->segments == NULL);
-
-  (* GTS_OBJECT_CLASS (gts_vertex_class ())->parent_class->destroy) (object);
-}
-
-static void vertex_clone (GtsObject * clone, GtsObject * object)
-{
-  (* GTS_OBJECT_CLASS (gts_vertex_class ())->parent_class->clone) (clone, 
-								   object);
-  GTS_VERTEX (clone)->segments = NULL;
-}
-
-static void vertex_class_init (GtsVertexClass * klass)
-{
-  klass->intersection_attributes = NULL;
-  GTS_OBJECT_CLASS (klass)->clone = vertex_clone;
-  GTS_OBJECT_CLASS (klass)->destroy = vertex_destroy;
-}
-
-static void vertex_init (GtsVertex * vertex)
-{
-  vertex->segments = NULL;
-}
-
-/**
- * gts_vertex_class:
- *
- * Returns: the #GtsVertexClass.
- */
-GtsVertexClass * gts_vertex_class (void)
-{
-  static GtsVertexClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo vertex_info = {
-      "GtsVertex",
-      sizeof (GtsVertex),
-      sizeof (GtsVertexClass),
-      (GtsObjectClassInitFunc) vertex_class_init,
-      (GtsObjectInitFunc) vertex_init,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_point_class ()), 
-				  &vertex_info);
-  }
-
-  return klass;
-}
-
-/**
- * gts_vertex_new:
- * @klass: a #GtsVertexClass.
- * @x: the x-coordinate of the vertex to create.
- * @y: the y-coordinate of the vertex to create.
- * @z: the y-coordinate of the vertex to create.
- *
- * Returns: a new #GtsVertex with @x, @y and @z as coordinates.
- */
-GtsVertex * gts_vertex_new (GtsVertexClass * klass,
-			    gdouble x, gdouble y, gdouble z)
-{
-  GtsVertex * v;
-
-  v = GTS_VERTEX (gts_object_new (GTS_OBJECT_CLASS (klass)));
-  gts_point_set (GTS_POINT (v), x, y, z);
-
-  return v;
-}
-
-/**
- * gts_vertex_replace:
- * @v: a #GtsVertex.
- * @with: another #GtsVertex.
- *
- * Replaces vertex @v with vertex @with. @v and @with must be
- * different.  All the #GtsSegment which have @v has one of their
- * vertices are updated.  The segments list of vertex @v is freed and
- * @v->segments is set to %NULL.  
- */
-void gts_vertex_replace (GtsVertex * v, GtsVertex * with)
-{
-  GSList * i;
-
-  g_return_if_fail (v != NULL);
-  g_return_if_fail (with != NULL);
-  g_return_if_fail (v != with);
-
-  i = v->segments;
-  while (i) {
-    GtsSegment * s = i->data;
-    if (s->v1 != with && s->v2 != with)
-      with->segments = g_slist_prepend (with->segments, s);
-    if (s->v1 == v) s->v1 = with;
-    if (s->v2 == v) s->v2 = with;
-    i = i->next;
-  }
-  g_slist_free (v->segments);
-  v->segments = NULL;
-}
-
-/**
- * gts_vertex_is_unattached:
- * @v: a #GtsVertex.
- *
- * Returns: %TRUE if @v is not the endpoint of any #GtsSegment, 
- * %FALSE otherwise.
- */
-gboolean gts_vertex_is_unattached (GtsVertex * v)
-{
-  g_return_val_if_fail (v != NULL, FALSE);
-  if (v->segments == NULL)
-    return TRUE;
-  return FALSE;
-}
-
-/**
- * gts_vertices_are_connected:
- * @v1: a #GtsVertex.
- * @v2: another #GtsVertex.
- *
- * Returns: if @v1 and @v2 are the vertices of the same #GtsSegment
- * this segment else %NULL.
- */
-GtsSegment * gts_vertices_are_connected (GtsVertex * v1, GtsVertex * v2)
-{
-  GSList * i;
-  
-  g_return_val_if_fail (v1 != NULL, FALSE);
-  g_return_val_if_fail (v2 != NULL, FALSE);
-  
-  i = v1->segments;
-  while (i) {
-    GtsSegment * s = i->data;
-
-    if (s->v1 == v2 || s->v2 == v2)
-      return s;
-    i = i->next;
-  }
-  return NULL;
-}
-
-/**
- * gts_vertices_from_segments:
- * @segments: a list of #GtsSegment.
- *
- * Returns: a list of #GtsVertex, vertices of a #GtsSegment in @segments.
- * Each element in the list is unique (no duplicates).
- */
-GSList * gts_vertices_from_segments (GSList * segments)
-{
-  GHashTable * hash;
-  GSList * vertices = NULL, * i;
-  
-  hash = g_hash_table_new (NULL, NULL);
-  i = segments;
-  while (i) {
-    GtsSegment * s = i->data;
-    if (g_hash_table_lookup (hash, s->v1) == NULL) {
-      vertices = g_slist_prepend (vertices, s->v1);
-      g_hash_table_insert (hash, s->v1, s);
-    }
-    if (g_hash_table_lookup (hash, s->v2) == NULL) {
-      vertices = g_slist_prepend (vertices, s->v2);
-      g_hash_table_insert (hash, s->v2, s);
-    }
-    i = i->next;
-  }
-  g_hash_table_destroy (hash);
-  return vertices;
-}
-
-/**
- * gts_vertex_triangles:
- * @v: a #GtsVertex.
- * @list: a list of #GtsTriangle.
- *
- * Adds all the #GtsTriangle which share @v as a vertex and do not
- * already belong to @list.
- *
- * Returns: the new list of unique #GtsTriangle which share @v as a
- * vertex.  
- */
-GSList * gts_vertex_triangles (GtsVertex * v, 
-			       GSList * list)
-{
-  GSList * i;
-
-  g_return_val_if_fail (v != NULL, NULL);
-
-  i = v->segments;
-  while (i) {
-    GtsSegment * s = i->data;
-    if (GTS_IS_EDGE (s)) {
-      GSList * j = GTS_EDGE (s)->triangles;
-      while (j) {
-	if (!g_slist_find (list, j->data))
-	  list = g_slist_prepend (list, j->data);
-	j = j->next;
-      }
-    }
-    i = i->next;
-  }
-  return list;
-}
-
-/**
- * gts_vertex_faces:
- * @v: a #GtsVertex.
- * @surface: a #GtsSurface or %NULL.
- * @list: a list of #GtsFace.
- *
- * Adds all the #GtsFace belonging to @surface (if not %NULL) which share 
- * @v as a vertex and do not already belong to @list.
- *
- * Returns: the new list of unique #GtsFace belonging to @surface 
- * which share @v as a vertex.
- */
-GSList * gts_vertex_faces (GtsVertex * v, 
-			   GtsSurface * surface, 
-			   GSList * list)
-{
-  GSList * i;
-
-  g_return_val_if_fail (v != NULL, NULL);
-
-  i = v->segments;
-  while (i) {
-    GtsSegment * s = i->data;
-    if (GTS_IS_EDGE (s)) {
-      GSList * j = GTS_EDGE (s)->triangles;
-      while (j) {
-	GtsTriangle * t = j->data;
-	if (GTS_IS_FACE (t) 
-	    && 
-	    (!surface || gts_face_has_parent_surface (GTS_FACE (t), surface)) 
-	    &&
-	    !g_slist_find (list, t))
-	  list = g_slist_prepend (list, t);
-	j = j->next;
-      }
-    }
-    i = i->next;
-  }
-  return list;
-}
-
-/**
- * gts_vertex_neighbors:
- * @v: a #GtsVertex.
- * @list: a list of #GtsVertex.
- * @surface: a #GtsSurface or %NULL.
- *
- * Adds to @list all the #GtsVertex connected to @v by a #GtsSegment and not
- * already in @list. If @surface is not %NULL only the vertices connected to
- * @v by an edge belonging to @surface are considered.
- *
- * Returns: the new list of unique #GtsVertex.
- */
-GSList * gts_vertex_neighbors (GtsVertex * v, 
-			       GSList * list,
-			       GtsSurface * surface)
-{
-  GSList * i;
-
-  g_return_val_if_fail (v != NULL, NULL);
-
-  i = v->segments;
-  while (i) {
-    GtsSegment * s = i->data;
-    GtsVertex * v1 = s->v1 == v ? s->v2 : s->v1;
-    if (v1 != v && 
-	(!surface || 
-	 (GTS_IS_EDGE (s) && 
-	  gts_edge_has_parent_surface (GTS_EDGE (s), surface))) &&
-	!g_slist_find (list, v1))
-      list = g_slist_prepend (list, v1);
-    i = i->next;
-  }
-  return list;
-}
-
-/**
- * gts_vertex_is_boundary:
- * @v: a #GtsVertex.
- * @surface: a #GtsSurface or %NULL.
- * 
- * Returns: %TRUE if @v is used by a #GtsEdge boundary of @surface as
- * determined by gts_edge_is_boundary(), %FALSE otherwise.
- */
-gboolean gts_vertex_is_boundary (GtsVertex * v, GtsSurface * surface)
-{
-  GSList * i;
-
-  g_return_val_if_fail (v != NULL, FALSE);
-  
-  i = v->segments;
-  while (i) {
-    if (GTS_IS_EDGE (i->data) && 
-	gts_edge_is_boundary (i->data, surface))
-      return TRUE;
-    i = i->next;
-  }
-
-  return FALSE;
-}
-
-/**
- * gts_vertices_merge:
- * @vertices: a list of #GtsVertex.
- * @epsilon: half the size of the bounding box to consider for each vertex.
- * @check: function called for each pair of vertices about to be merged
- * or %NULL.
- *
- * For each vertex v in @vertices look if there are any vertex of
- * @vertices contained in a box centered on v of size 2*@epsilon. If
- * there are and if @check is not %NULL and returns %TRUE, replace
- * them with v (using gts_vertex_replace()), destroy them and remove
- * them from list.  This is done efficiently using Kd-Trees.
- *
- * Returns: the updated list of vertices.  
- */
-GList * gts_vertices_merge (GList * vertices, 
-			    gdouble epsilon,
-			    gboolean (* check) (GtsVertex *, GtsVertex *))
-{
-  GPtrArray * array;
-  GList * i;
-  GNode * kdtree;
-
-  g_return_val_if_fail (vertices != NULL, 0);
-
-  array = g_ptr_array_new ();
-  i = vertices;
-  while (i) {
-    g_ptr_array_add (array, i->data);
-    i = i->next;
-  }
-  kdtree = gts_kdtree_new (array, NULL);
-  g_ptr_array_free (array, TRUE);
-  
-  i = vertices;
-  while (i) {
-    GtsVertex * v = i->data;
-    if (!GTS_OBJECT (v)->reserved) { /* Do something only if v is active */
-      GtsBBox * bbox;
-      GSList * selected, * j;
-
-      /* build bounding box */
-      bbox = gts_bbox_new (gts_bbox_class (),
-			   v, 
-			   GTS_POINT (v)->x - epsilon,
-			   GTS_POINT (v)->y - epsilon,
-			   GTS_POINT (v)->z - epsilon,
-			   GTS_POINT (v)->x + epsilon,
-			   GTS_POINT (v)->y + epsilon,
-			   GTS_POINT (v)->z + epsilon);
-
-      /* select vertices which are inside bbox using kdtree */
-      j = selected = gts_kdtree_range (kdtree, bbox, NULL);
-      while (j) {
-	GtsVertex * sv = j->data;
-	if (sv != v && !GTS_OBJECT (sv)->reserved && (!check || (*check) (sv, v))) {
-	  /* sv is not v and is active */
-	  gts_vertex_replace (sv, v);
-	  GTS_OBJECT (sv)->reserved = sv; /* mark sv as inactive */
-	}
-	j = j->next;
-      }
-      g_slist_free (selected);
-      gts_object_destroy (GTS_OBJECT (bbox));
-    }
-    i = i->next;
-  }
-
-  gts_kdtree_destroy (kdtree);
-
-  /* destroy inactive vertices and removes them from list */
-
-  /* we want to control vertex destruction */
-  gts_allow_floating_vertices = TRUE;
-
-  i = vertices;
-  while (i) {
-    GtsVertex * v = i->data;
-    GList * next = i->next;
-    if (GTS_OBJECT (v)->reserved) { /* v is inactive */
-      gts_object_destroy (GTS_OBJECT (v));
-      vertices = g_list_remove_link (vertices, i);
-      g_list_free_1 (i);
-    }
-    i = next;
-  }
-  gts_allow_floating_vertices = FALSE; 
-
-  return vertices;
-}
-
-/* returns the list of edges belonging to @surface turning around @v */
-static GSList * edge_fan_list (GtsVertex * v,
-			       GtsSurface * surface,
-			       GtsFace * f, 
-			       GtsEdge * e,
-			       GtsFace * first)
-{
-  GSList * i = e->triangles;
-  GtsFace * neighbor = NULL;
-  GtsEdge * next = NULL, * enext = NULL;
-
-  while (i) {
-    GtsFace * f1 = i->data;
-    if (GTS_IS_FACE (f1) &&
-	f1 != f &&
-	gts_face_has_parent_surface (f1, surface)) {
-      g_return_val_if_fail (neighbor == NULL, NULL); /* non-manifold edge */
-      neighbor = f1;
-    }
-    i = i->next;
-  }
-  if (neighbor == NULL || neighbor == first) /* end of fan */
-    return NULL;
-
-  if (GTS_TRIANGLE (neighbor)->e1 == e) {
-    next = GTS_TRIANGLE (neighbor)->e2;
-    enext = GTS_TRIANGLE (neighbor)->e3;
-  }
-  else if (GTS_TRIANGLE (neighbor)->e2 == e) {
-    next = GTS_TRIANGLE (neighbor)->e3;
-    enext = GTS_TRIANGLE (neighbor)->e1;
-  }
-  else if (GTS_TRIANGLE (neighbor)->e3 == e) {
-    next = GTS_TRIANGLE (neighbor)->e1;
-    enext = GTS_TRIANGLE (neighbor)->e2;
-  }
-  else
-    g_assert_not_reached ();
-
-  /* checking for correct orientation */
-  g_return_val_if_fail (GTS_SEGMENT (enext)->v1 == v ||
-			GTS_SEGMENT (enext)->v2 == v, NULL);
-
-  return g_slist_prepend (edge_fan_list (v, surface, neighbor, enext, first), 
-			  next);
-}
-
-/**
- * gts_vertex_fan_oriented:
- * @v: a #GtsVertex.
- * @surface: a #GtsSurface.
- *
- * Returns: a list of #GtsEdge describing in counterclockwise order the 
- * boundary of the fan of summit @v, the faces of the fan belonging to 
- * @surface.
- */
-GSList * gts_vertex_fan_oriented (GtsVertex * v, GtsSurface * surface)
-{
-  GtsFace * f = NULL;
-  guint d = 2;
-  GSList * i;
-  GtsVertex * v1, * v2, * v3;
-  GtsEdge * e1, * e2, * e3;
-
-  g_return_val_if_fail (v != NULL, NULL);
-  g_return_val_if_fail (surface != NULL, NULL);
-
-  i = v->segments;
-  while (i) {
-    GtsEdge * e = i->data;
-    if (GTS_IS_EDGE (e)) {
-      GSList * j = e->triangles;
-      GtsFace * f1 = NULL;
-      guint degree = 0;
-      while (j) {
-	if (GTS_IS_FACE (j->data) &&
-	    gts_face_has_parent_surface (j->data, surface)) {
-	  f1 = j->data;
-	  degree++;
-	}
-	j = j->next;
-      }
-      if (f1 != NULL) {
-	g_return_val_if_fail (degree <= 2, NULL); /* non-manifold edge */
-	if (degree == 1) {
-	  gts_triangle_vertices_edges (GTS_TRIANGLE (f1), NULL,
-				       &v1, &v2, &v3, &e1, &e2, &e3);
-	  if (v == v2) {
-	    e2 = e3;
-	    e3 = e1;
-	  }
-	  else if (v == v3) {
-	    e3 = e2;
-	    e2 = e1;
-	  }
-	  if (e3 != e) {
-	    d = 1;
-	    f = f1;
-	  }
-	}
-	else if (degree <= d)
-	  f = f1;
-      }
-    }
-    i = i->next;
-  }
-
-  if (f == NULL)
-    return NULL;
-
-  gts_triangle_vertices_edges (GTS_TRIANGLE (f), NULL,
-			       &v1, &v2, &v3, &e1, &e2, &e3);
-  if (v == v2) {
-    e2 = e3;
-    e3 = e1;
-  }
-  else if (v == v3) {
-    e3 = e2;
-    e2 = e1;
-  }
-
-  return g_slist_prepend (edge_fan_list (v, surface, f, e3, f), e2);
-}
-
-#define edge_use_vertex(e, v) (GTS_SEGMENT(e)->v1 == v ||\
-			       GTS_SEGMENT(e)->v2 == v)
-
-static GtsEdge * replace_vertex (GtsTriangle * t, 
-				 GtsEdge * e1,
-				 GtsVertex * v, 
-				 GtsVertex * with)
-{
-  GtsEdge * e = NULL;
-
-  if (t->e1 != e1 && edge_use_vertex (t->e1, v))
-    e = t->e1;
-  else if (t->e2 != e1 && edge_use_vertex (t->e2, v))
-    e = t->e2;
-  else if (t->e3 != e1 && edge_use_vertex (t->e3, v))
-    e = t->e3;
-  else
-    return NULL;
-
-  if (with != v) {
-    GtsSegment * s = GTS_SEGMENT (e);
-    if (s->v1 == v) s->v1 = with;
-    if (s->v2 == v) s->v2 = with;
-    with->segments = g_slist_prepend (with->segments, s);
-    v->segments = g_slist_remove (v->segments, s);
-  }
-
-  return e;
-}
-
-static void triangle_next (GtsEdge * e, GtsVertex * v, GtsVertex * with)
-{
-  GSList * i;
-
-  if (e == NULL)
-    return;
-    
-  i = e->triangles;
-  while (i) {
-    GtsTriangle * t = i->data;
-    if (GTS_OBJECT (t)->reserved) {
-      GTS_OBJECT (t)->reserved = NULL;
-      triangle_next (replace_vertex (t, e, v, with), v, with);
-    }
-    i = i->next;
-  }
-}
-
-/** 
- * gts_vertex_is_contact: 
- * @v: a #GtsVertex.  
- * @sever: if %TRUE and if @v is a contact vertex between two or more
- * sets of connected triangles replaces it with as many vertices,
- * clones of @v.
- *
- * Returns: the number of sets of connected triangles sharing @v as a
- * contact vertex.  
- */
-guint gts_vertex_is_contact (GtsVertex * v, gboolean sever)
-{
-  GSList * triangles, * i;
-  GtsVertex * with = v;
-  guint ncomponent = 0;
-
-  g_return_val_if_fail (v != NULL, 0);
-
-  triangles = gts_vertex_triangles (v, NULL);
-  i = triangles;
-  while (i) {
-    GTS_OBJECT (i->data)->reserved = i;
-    i = i->next;
-  }
-
-  i = triangles;
-  while (i) {
-    GtsTriangle * t = i->data;
-    if (GTS_OBJECT (t)->reserved) {
-      GtsEdge * e;
-      if (ncomponent && sever)
-	with = GTS_VERTEX (gts_object_clone (GTS_OBJECT (v)));
-      GTS_OBJECT (t)->reserved = NULL;
-      e = replace_vertex (t, NULL, v, with);
-      triangle_next (e, v, with);
-      triangle_next (replace_vertex (t, e, v, with), v, with);
-      ncomponent++;
-    }
-    i = i->next;
-  }
-  g_slist_free (triangles);
-
-  return ncomponent;
-}
-
-/* GtsVertexNormal: Object */
-
-static void vertex_normal_attributes (GtsVertex * v,
-				      GtsObject * e,
-				      GtsObject * t)
-{
-  g_return_if_fail (GTS_IS_EDGE (e));
-  g_return_if_fail (GTS_IS_TRIANGLE (t));
-
-  if (GTS_IS_VERTEX_NORMAL (GTS_SEGMENT (e)->v1) &&
-      GTS_IS_VERTEX_NORMAL (GTS_SEGMENT (e)->v2)) {
-    GtsPoint * p1 = GTS_POINT (GTS_SEGMENT (e)->v1);
-    GtsPoint * p2 = GTS_POINT (GTS_SEGMENT (e)->v2);
-    GtsPoint * p = GTS_POINT (v);
-    gdouble a, b, lambda;
-    guint i;
-
-    a = p2->x - p1->x; b = p->x - p1->x;
-    if (fabs (p2->y - p1->y) > fabs (a)) {
-      a = p2->y - p1->y; b = p->y - p1->y;      
-    }
-    if (fabs (p2->z - p1->z) > fabs (a)) {
-      a = p2->z - p1->z; b = p->z - p1->z;      
-    }
-    lambda = a != 0. ? b/a : 0.;
-    for (i = 0; i < 3; i++)
-      GTS_VERTEX_NORMAL (v)->n[i] = 
-	(1. - lambda)*GTS_VERTEX_NORMAL (GTS_SEGMENT (e)->v1)->n[i] +
-	lambda*GTS_VERTEX_NORMAL (GTS_SEGMENT (e)->v2)->n[i];
-  }
-  else {
-    GtsVertex * v1, * v2, * v3;
-
-    gts_triangle_vertices (GTS_TRIANGLE (t), &v1, &v2, &v3);
-    if (GTS_IS_VERTEX_NORMAL (v1) && 
-	GTS_IS_VERTEX_NORMAL (v2) &&
-	GTS_IS_VERTEX_NORMAL (v3)) {
-      GtsVector a1, a2, a3, det;
-      guint i, j = 0;
-      gdouble l1, l2;
-
-      gts_vector_init (a1, GTS_POINT (v1), GTS_POINT (v));
-      gts_vector_init (a2, GTS_POINT (v1), GTS_POINT (v2));
-      gts_vector_init (a3, GTS_POINT (v1), GTS_POINT (v3));
-      gts_vector_cross (det, a2, a3);
-      if (fabs (det[1]) > fabs (det[0])) j = 1;
-      if (fabs (det[2]) > fabs (det[j])) j = 2;
-      if (det[j] == 0.) {
-	g_warning ("vertex_normal_attributes: det[%d] == 0.", j);
-	return;
-      }
-      switch (j) {
-      case 0: 
-	l1 = (a1[1]*a3[2] - a1[2]*a3[1])/det[0]; 
-	l2 = (a1[2]*a2[1] - a1[1]*a2[2])/det[0]; 
-	break;
-      case 1:
-	l1 = (a1[2]*a3[0] - a1[0]*a3[2])/det[1];
-	l2 = (a1[0]*a2[2] - a1[2]*a2[0])/det[1];
-	break;
-      case 2:
-	l1 = (a1[0]*a3[1] - a1[1]*a3[0])/det[2];
-	l2 = (a1[1]*a2[0] - a1[0]*a2[1])/det[2];
-	break;
-      default:
-	l1 = l2 = 0.;
-      }
-      for (i = 0; i < 3; i++)
-	GTS_VERTEX_NORMAL (v)->n[i] = 
-	  GTS_VERTEX_NORMAL (v1)->n[i]*(1. - l1 - l2) +
-	  GTS_VERTEX_NORMAL (v2)->n[i]*l1 +
-	  GTS_VERTEX_NORMAL (v3)->n[i]*l2;
-    }
-  }
-}
-
-static void gts_vertex_normal_class_init (GtsVertexClass * klass)
-{
-  klass->intersection_attributes = vertex_normal_attributes;
-}
-
-GtsVertexClass * gts_vertex_normal_class (void)
-{
-  static GtsVertexClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo gts_vertex_normal_info = {
-      "GtsVertexNormal",
-      sizeof (GtsVertexNormal),
-      sizeof (GtsVertexClass),
-      (GtsObjectClassInitFunc) gts_vertex_normal_class_init,
-      (GtsObjectInitFunc) NULL,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_vertex_class ()),
-				  &gts_vertex_normal_info);
-  }
-
-  return klass;
-}
-
-/* GtsColorVertex: Object */
-
-GtsVertexClass * gts_color_vertex_class (void)
-{
-  static GtsVertexClass * klass = NULL;
-
-  if (klass == NULL) {
-    GtsObjectClassInfo gts_color_vertex_info = {
-      "GtsColorVertex",
-      sizeof (GtsColorVertex),
-      sizeof (GtsVertexClass),
-      (GtsObjectClassInitFunc) NULL,
-      (GtsObjectInitFunc) NULL,
-      (GtsArgSetFunc) NULL,
-      (GtsArgGetFunc) NULL
-    };
-    klass = gts_object_class_new (GTS_OBJECT_CLASS (gts_vertex_class ()),
-				  &gts_color_vertex_info);
-  }
-
-  return klass;
-}
-
diff --git a/src/gts/vopt.c b/src/gts/vopt.c
deleted file mode 100644
index d772af9..0000000
--- a/src/gts/vopt.c
+++ /dev/null
@@ -1,521 +0,0 @@
-/* GTS - Library for the manipulation of triangulated surfaces
- * Copyright (C) 1999 Stéphane Popinet
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- */
-
-#include "gts.h"
-
-/* #define DEBUG_VOPT */
-
-/* compute the normal (nx, ny, nz) as the cross-product of the first two 
-   oriented edges and the norm nt = |t| as (v1xv2).v3 */
-static void triangle_normal (GtsTriangle * t, 
-			     gdouble * nx, 
-			     gdouble * ny, 
-			     gdouble * nz,
-			     gdouble * nt)
-{
-  GtsPoint * p1, * p2 = NULL, * p3 = NULL;
-  gdouble x1, y1, z1, x2, y2, z2;
-
-  g_return_if_fail (t != NULL);
-
-  p1 = GTS_POINT (GTS_SEGMENT (t->e1)->v1);
-  if (GTS_SEGMENT (t->e1)->v1 == GTS_SEGMENT (t->e2)->v1) {
-    p2 = GTS_POINT (GTS_SEGMENT (t->e2)->v2);
-    p3 = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
-  }
-  else if (GTS_SEGMENT (t->e1)->v2 == GTS_SEGMENT (t->e2)->v2) {
-    p2 = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
-    p3 = GTS_POINT (GTS_SEGMENT (t->e2)->v1);
-  }
-  else if (GTS_SEGMENT (t->e1)->v1 == GTS_SEGMENT (t->e2)->v2) {
-    p2 = GTS_POINT (GTS_SEGMENT (t->e2)->v1);
-    p3 = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
-  }
-  else if (GTS_SEGMENT (t->e1)->v2 == GTS_SEGMENT (t->e2)->v1) {
-    p2 = GTS_POINT (GTS_SEGMENT (t->e1)->v2);
-    p3 = GTS_POINT (GTS_SEGMENT (t->e2)->v2);
-  }
-  else
-    g_assert_not_reached ();
-
-  x1 = p2->x - p1->x;
-  y1 = p2->y - p1->y;
-  z1 = p2->z - p1->z;
-
-  x2 = p3->x - p1->x;
-  y2 = p3->y - p1->y;
-  z2 = p3->z - p1->z;
-
-  *nt = ((p1->y*p2->z - p1->z*p2->y)*p3->x + 
-	 (p1->z*p2->x - p1->x*p2->z)*p3->y + 
-	 (p1->x*p2->y - p1->y*p2->x)*p3->z);
-  *nx = y1*z2 - z1*y2;
-  *ny = z1*x2 - x1*z2;
-  *nz = x1*y2 - y1*x2;
-}
-
-static void boundary_preservation (GtsEdge * edge,
-				   GtsFace * f,
-				   GtsVector e1, GtsVector e2,
-				   GtsMatrix * H, GtsVector c)
-{
-  GtsTriangle * t = GTS_TRIANGLE (f);
-  GtsEdge * edge2;
-  GtsVertex * v1 = GTS_SEGMENT (edge)->v1, * v2 = GTS_SEGMENT (edge)->v2;
-  GtsPoint * p1, * p2;
-  GtsVector e, e3;
-
-  /* find orientation of segment */
-  edge2 = edge == t->e1 ? t->e2 : edge == t->e2 ? t->e3 : t->e1;
-  if (v2 != GTS_SEGMENT (edge2)->v1 && v2 != GTS_SEGMENT (edge2)->v2) {
-    v2 = v1; v1 = GTS_SEGMENT (edge)->v2;
-  }
-  p1 = GTS_POINT (v1);
-  p2 = GTS_POINT (v2);
-
-  e[0] = p2->x - p1->x;
-  e[1] = p2->y - p1->y;
-  e[2] = p2->z - p1->z;
-
-  e1[0] += e[0];
-  e1[1] += e[1];
-  e1[2] += e[2];
-
-  e3[0] = p2->y*p1->z - p2->z*p1->y;
-  e3[1] = p2->z*p1->x - p2->x*p1->z;
-  e3[2] = p2->x*p1->y - p2->y*p1->x;
-
-  e2[0] += e3[0];
-  e2[1] += e3[1];
-  e2[2] += e3[2];
-
-  H[0][0] += e[1]*e[1] + e[2]*e[2];
-  H[0][1] -= e[0]*e[1];
-  H[0][2] -= e[0]*e[2];
-  H[1][0] = H[0][1];
-  H[1][1] += e[0]*e[0] + e[2]*e[2];
-  H[1][2] -= e[1]*e[2];
-  H[2][0] = H[0][2];
-  H[2][1] = H[1][2];
-  H[2][2] += e[0]*e[0] + e[1]*e[1];
-
-  c[0] += e[1]*e3[2] - e[2]*e3[1];
-  c[1] += e[2]*e3[0] - e[0]*e3[2];
-  c[2] += e[0]*e3[1] - e[1]*e3[0];
-}
-
-static gdouble boundary_cost (GtsEdge * edge, 
-			      GtsFace * f,
-			      GtsVertex * v)
-{
-  GtsTriangle * t = GTS_TRIANGLE (f);
-  GtsEdge * edge2;
-  GtsVertex * v1 = GTS_SEGMENT (edge)->v1, * v2 = GTS_SEGMENT (edge)->v2;
-  GtsPoint * p1, * p2;
-  GtsVector e;
-  GtsPoint * p = GTS_POINT (v);
-
-  /* find orientation of segment */
-  edge2 = edge == t->e1 ? t->e2 : edge == t->e2 ? t->e3 : t->e1;
-  if (v2 != GTS_SEGMENT (edge2)->v1 && v2 != GTS_SEGMENT (edge2)->v2) {
-    v2 = v1; v1 = GTS_SEGMENT (edge)->v2;
-  }
-  p1 = GTS_POINT (v1);
-  p2 = GTS_POINT (v2);  
-
-  e[0] = (p2->y - p1->y)*(p->z - p2->z) - (p2->z - p1->z)*(p->y - p2->y);
-  e[1] = (p2->z - p1->z)*(p->x - p2->x) - (p2->x - p1->x)*(p->z - p2->z);
-  e[2] = (p2->x - p1->x)*(p->y - p2->y) - (p2->y - p1->y)*(p->x - p2->x);
-
-  return e[0]*e[0] + e[1]*e[1] + e[2]*e[2];
-}
-
-static gdouble edge_boundary_cost (GtsEdge * e, GtsVertex * v)
-{
-  gdouble cost = 0.;
-  GSList * i;
-
-  i = GTS_SEGMENT (e)->v1->segments;
-  while (i) {
-    GtsFace * f;
-    if (GTS_IS_EDGE (i->data) && 
-	(f = gts_edge_is_boundary (i->data, NULL)))
-      cost += boundary_cost (i->data, f, v);
-    i = i->next;
-  }
-  i = GTS_SEGMENT (e)->v2->segments;
-  while (i) {
-    GtsFace * f;
-    if (i->data != e && 
-	GTS_IS_EDGE (i->data) && 
-	(f = gts_edge_is_boundary (i->data, NULL)))
-      cost += boundary_cost (i->data, f, v);
-    i = i->next;
-  }
-
-  return cost/4.;
-}
-
-static gdouble edge_volume_cost (GtsEdge * e, GtsVertex * v)
-{
-  GSList * i, * triangles;
-  gdouble n1, n2, n3, nt;
-  gdouble cost = 0.0, a;
-
-  triangles = gts_vertex_triangles (GTS_SEGMENT (e)->v1, NULL);
-  triangles = gts_vertex_triangles (GTS_SEGMENT (e)->v2, triangles);
-
-  i = triangles;
-  while (i) {
-    if (GTS_IS_FACE (i->data)) {
-      triangle_normal (i->data, &n1, &n2, &n3, &nt);
-      a = GTS_POINT (v)->x*n1 + 
-	GTS_POINT (v)->y*n2 + 
-	GTS_POINT (v)->z*n3 - nt;
-      cost += a*a;
-    }
-    i = i->next;
-  }
-  g_slist_free (triangles);
-
-  return cost/36.;
-}
-
-static gdouble edge_shape_cost (GtsEdge * e, GtsVertex * v)
-{
-  GSList * list, * i;
-  GtsVertex 
-    * v1 = GTS_SEGMENT (e)->v1,
-    * v2 = GTS_SEGMENT (e)->v2;
-  gdouble cost = 0.;
-
-  list = gts_vertex_neighbors (v1, NULL, NULL);
-  list = gts_vertex_neighbors (v2, list, NULL);
-  i = list;
-  while (i) {
-    GtsPoint * p = i->data;
-    if (p != GTS_POINT (v1) && p != GTS_POINT (v2))
-      cost += gts_point_distance2 (p, GTS_POINT (v));
-    i = i->next;
-  }
-  g_slist_free (list);
-
-  return cost;
-}
-
-/**
- * gts_volume_optimized_vertex:
- * @edge: a #GtsEdge.
- * @klass: a #GtsVertexClass to be used for the new vertex.
- * @params: a #GtsVolumeOptimizedParms.
- *
- * Returns: a #GtsVertex which can be used to replace @edge for an
- * edge collapse operation. The position of the vertex is optimized in
- * order to minimize the changes in area and volume for the surface
- * using @edge. The volume enclosed by the surface is locally
- * preserved. For more details see "Fast and memory efficient
- * polygonal simplification" (1998) and "Evaluation of memoryless
- * simplification" (1999) by Lindstrom and Turk.  
- */
-GtsVertex * gts_volume_optimized_vertex (GtsEdge * edge,
-					 GtsVertexClass * klass,
-					 GtsVolumeOptimizedParams * params)
-{
-  GSList * triangles, * i;
-  gdouble sn1 = 0., sn2 = 0., sn3 = 0.;
-  gdouble sn11 = 0., sn22 = 0., sn33 = 0.;
-  gdouble sn12 = 0., sn13 = 0., sn23 = 0.;
-  gdouble st = 0., stn1 = 0., stn2 = 0., stn3 = 0.;
-  gdouble n1, n2, n3, nt;
-  GtsMatrix * A, * Ai;
-  GtsVector A1, b;
-  GtsVector e1 = {0., 0., 0.}, e2 = {0., 0., 0.};
-  GtsMatrix * Hb;
-  GtsVector cb = {0., 0., 0.};
-  GtsVertex * v;
-  GtsVertex * v1, * v2;
-  guint n = 0, nb = 0;
-#ifdef DEBUG_VOPT
-  guint nold = 0;
-#endif
-
-  g_return_val_if_fail (edge != NULL, NULL);
-  g_return_val_if_fail (klass != NULL, NULL);
-  g_return_val_if_fail (params != NULL, NULL);
-
-  A = gts_matrix_zero (NULL);
-  Hb = gts_matrix_zero (NULL);
-  v1 = GTS_SEGMENT (edge)->v1;
-  v2 = GTS_SEGMENT (edge)->v2;
-
-  /* boundary preservation */
-  i = v1->segments;
-  while (i) {
-    GtsEdge * edge1 = i->data;
-    GtsFace * f;
-    if (GTS_IS_EDGE (edge1) &&
-	(f = gts_edge_is_boundary (edge1, NULL))) {
-      boundary_preservation (edge1, f, e1, e2, Hb, cb);
-      nb++;
-    }
-    i = i->next;
-  }
-  i = v2->segments;
-  while (i) {
-    GtsEdge * edge1 = i->data;
-    GtsFace * f;
-    if (edge1 != edge && 
-	GTS_IS_EDGE (edge1) &&
-	(f = gts_edge_is_boundary (edge1, NULL))) {
-      boundary_preservation (edge1, f, e1, e2, Hb, cb);
-      nb++;
-    }
-    i = i->next;
-  }
-  if (nb > 0) {
-    GtsMatrix * H = gts_matrix_new (
-	       e1[2]*e1[2] + e1[1]*e1[1], - e1[0]*e1[1], - e1[0]*e1[2], 0.,
-	       - e1[0]*e1[1], e1[2]*e1[2] + e1[0]*e1[0], - e1[1]*e1[2], 0.,
-	       - e1[0]*e1[2], - e1[1]*e1[2], e1[1]*e1[1] + e1[0]*e1[0], 0.,
-	       0., 0., 0., 0.);
-    GtsVector c;
-
-    c[0] = e1[1]*e2[2] - e1[2]*e2[1];
-    c[1] = e1[2]*e2[0] - e1[0]*e2[2];
-    c[2] = e1[0]*e2[1] - e1[1]*e2[0];
-    n = gts_matrix_quadratic_optimization (A, b, n, H, c);
-    gts_matrix_destroy (H);
-  }
-
-  g_assert (n <= 2);
-
-#ifdef DEBUG_VOPT
-  if (n != nold) {
-    fprintf (stderr, "--- boundary preservation ---\n");
-    gts_matrix_print (A, stderr);
-    gts_vector_print (b, stderr);
-    nold = n;
-  }
-#endif
-
-  /* volume preservation */
-  triangles = gts_vertex_triangles (v1, NULL);
-  triangles = gts_vertex_triangles (v2, triangles);
-
-  i = triangles;
-  while (i) {
-    if (GTS_IS_FACE (i->data)) {
-      triangle_normal (i->data, &n1, &n2, &n3, &nt);
-      sn1 += n1; sn2 += n2; sn3 += n3;
-      sn11 += n1*n1; sn22 += n2*n2; sn33 += n3*n3;
-      sn12 += n1*n2; sn13 += n1*n3; sn23 += n2*n3;
-      st += nt; stn1 += nt*n1; stn2 += nt*n2; stn3 += nt*n3;
-    }
-    i = i->next;
-  }
-  g_slist_free (triangles);
-
-  A1[0] = sn1; A1[1] = sn2; A1[2] = sn3;
-  n = gts_matrix_compatible_row (A, b, n, A1, st);
-
-#ifdef DEBUG_VOPT
-  if (n != nold) {
-    fprintf (stderr, "--- volume preservation ---\n");
-    gts_matrix_print (A, stderr);
-    gts_vector_print (b, stderr);
-    nold = n;
-  }
-#endif
-
-#if 1 /* Weighted average of volume and boundary optimization */
-  if (n < 3) {
-    /* volume optimization and boundary optimization */
-    GtsMatrix * H = gts_matrix_new (sn11, sn12, sn13, 0.,
-				    sn12, sn22, sn23, 0.,
-				    sn13, sn23, sn33, 0.,
-				    0., 0., 0., 0.);
-    GtsVector c;
-    gdouble le = 9.*params->boundary_weight*
-      gts_point_distance2 (GTS_POINT (v1), 
-			   GTS_POINT (v2));
-    guint i, j;
-
-    c[0] = - stn1; c[1] = - stn2; c[2] = - stn3;
-    if (nb > 0)
-      for (i = 0; i < 3; i++) {
-	for (j = 0; j < 3; j++)
-	  H[i][j] = params->volume_weight*H[i][j] + le*Hb[i][j];
-	c[i] = params->volume_weight*c[i] + le*cb[i];
-      }
-    n = gts_matrix_quadratic_optimization (A, b, n, H, c);
-    gts_matrix_destroy (H);
-  }
-
-#ifdef DEBUG_VOPT
-  if (n != nold) {
-    fprintf (stderr, "--- volume and boundary optimization ---\n");
-    gts_matrix_print (A, stderr);
-    gts_vector_print (b, stderr);
-    nold = n;
-  }
-#endif
-
-  if (n < 3) {
-    /* triangle shape optimization */
-    gdouble nv = 0.0;
-    GtsMatrix * H;
-    GtsVector c = {0., 0., 0.};
-    GSList * list, * i;
-
-    list = gts_vertex_neighbors (v1, NULL, NULL);
-    list = gts_vertex_neighbors (v2, list, NULL);
-
-    i = list;
-    while (i) {
-      GtsPoint * p1 = i->data;
-      if (p1 != GTS_POINT (v1) && p1 != GTS_POINT (v2)) {
-	nv += 1.0;
-	c[0] -= p1->x;
-	c[1] -= p1->y;
-	c[2] -= p1->z;
-      }
-      i = i->next;
-    }
-    g_slist_free (list);
-    
-    H = gts_matrix_new (nv, 0., 0., 0.,
-			0., nv, 0., 0.,
-			0., 0., nv, 0.,
-			0., 0., 0., 0.);
-    n = gts_matrix_quadratic_optimization (A, b, n, H, c);
-    gts_matrix_destroy (H);
-  }
-
-#ifdef DEBUG_VOPT
-  if (n != nold) {
-    fprintf (stderr, "--- triangle shape optimization ---\n");
-    gts_matrix_print (A, stderr);
-    gts_vector_print (b, stderr);
-    nold = n;
-  }
-#endif
-#else /* Weighted average of volume, boundary and shape optimization */
-  if (n < 3) {
-    /* volume optimization, boundary and shape optimization */
-    GtsMatrix * H; 
-    GtsVector c;
-    gdouble l2 = gts_point_distance2 (GTS_POINT (v1), 
-				      GTS_POINT (v2));
-    gdouble wv = params->volume_weight/32.;
-    gdouble wb = params->boundary_weight/4.*l2;
-    gdouble ws = params->shape_weight*l2*l2;
-    
-    gdouble nv = 0.0;
-    GtsVector cs = {0., 0., 0.};
-    GSList * list, * i;
-
-    list = gts_vertex_neighbors (v1, NULL, NULL);
-    list = gts_vertex_neighbors (v2, list, NULL);
-
-    i = list;
-    while (i) {
-      GtsPoint * p1 = i->data;
-      if (p1 != GTS_POINT (v1) && p1 != GTS_POINT (v2)) {
-	nv += 1.0;
-	cs[0] -= p1->x;
-	cs[1] -= p1->y;
-	cs[2] -= p1->z;
-      }
-      i = i->next;
-    }
-    g_slist_free (list);
-
-    H = gts_matrix_new (wv*sn11 + wb*Hb[0][0] + ws*nv, 
-			wv*sn12 + wb*Hb[0][1], 
-			wv*sn13 + wb*Hb[0][2],
-			wv*sn12 + wb*Hb[1][0], 
-			wv*sn22 + wb*Hb[1][1] + ws*nv, 
-			wv*sn23 + wb*Hb[1][2],
-			wv*sn13 + wb*Hb[2][0], 
-			wv*sn23 + wb*Hb[2][1], 
-			wv*sn33 + wb*Hb[2][2] + ws*nv);
-
-    c[0] = - wv*stn1 + wb*cb[0] + ws*cs[0];
-    c[1] = - wv*stn2 + wb*cb[1] + ws*cs[1];
-    c[2] = - wv*stn3 + wb*cb[2] + ws*cs[2];
-
-    n = gts_matrix_quadratic_optimization (A, b, n, H, c);
-    gts_matrix_destroy (H);
-  }
-
-#ifdef DEBUG_VOPT
-  if (n != nold) {
-    fprintf (stderr, "--- volume, boundary and shape optimization ---\n");
-    gts_matrix_print (A, stderr);
-    gts_vector_print (b, stderr);
-    nold = n;
-  }
-#endif
-#endif /* Weighted average of volume, boundary and shape optimization */
-
-  g_assert (n == 3);
-  g_assert ((Ai = gts_matrix3_inverse (A)));
-
-  v = gts_vertex_new (klass,
-		      Ai[0][0]*b[0] + Ai[0][1]*b[1] + Ai[0][2]*b[2],
-		      Ai[1][0]*b[0] + Ai[1][1]*b[1] + Ai[1][2]*b[2],
-		      Ai[2][0]*b[0] + Ai[2][1]*b[1] + Ai[2][2]*b[2]);
-
-  gts_matrix_destroy (A);
-  gts_matrix_destroy (Ai);
-  gts_matrix_destroy (Hb);
-  
-  return v;
-}
-
-/**
- * gts_volume_optimized_cost:
- * @e: a #GtsEdge.
- * @params: a #GtsVolumeOptimizedParams.
- * 
- * Returns: the cost for the collapse of @e as minimized by the function
- * gts_volume_optimized_vertex().
- */
-gdouble gts_volume_optimized_cost (GtsEdge * e, 
-				   GtsVolumeOptimizedParams * params)
-{
-  GtsVertex * v;
-  gdouble cost;
-  gdouble length2;
-
-  g_return_val_if_fail (e != NULL, G_MAXDOUBLE);
-  g_return_val_if_fail (params != NULL, G_MAXDOUBLE);
-
-  v = gts_volume_optimized_vertex (e, gts_vertex_class (), params);
-
-  length2 = gts_point_distance2 (GTS_POINT (GTS_SEGMENT (e)->v1), 
-				 GTS_POINT (GTS_SEGMENT (e)->v2));
-  cost = 
-    params->volume_weight*edge_volume_cost (e, v) +
-    params->boundary_weight*length2*edge_boundary_cost (e, v) +
-    params->shape_weight*length2*length2*edge_shape_cost (e, v);
-  gts_object_destroy (GTS_OBJECT (v));
-
-  return cost;
-}



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