Hi casey!
Yeh, unfortunately, I haven't found any smart ways to use retained
mode
for 2D graphics engines. Even if you do use VBO's in stream mode you
have
to update the data every frame, i.e a Python call that makes C
calls, all
those array structs have to be converted from Python types to C types
eventually as well. Also, changing textures requires immediate mode
calls.
From what little I know about it, my guess is that a C extension is
way faster than ctypes and SWIG generated code.
SWIG makes sense for an entire scenegraph written in C, the scenegraph
is retained in itself and will accept your data, including animations,
and continously executing it for you.
What most people want is a fast and simple scenegraph, that is
avoiding
shaders and the intricate details of opengl.
If you have solution for multiple textures in one VBO that does not
use shaders and
works in retained mode, please do share. I've been looking for ages.
With multiple textures I mean the ability to glBindTexture in retained
mode, not the use of multi textures.
/Peter
On 2009-03-17 (Tue) 21:43, Casey Duncan wrote:
With the emphasis these days on batch operations (VBOs, etc) and
doing
more and more of the work on the video card itself via shaders, I
seriously doubt that the bottleneck of a well-written, modern
PyOpenGL
application will be the ctypes overhead. The only time I could see
that
could be would be for immediate mode usage, which is deprecated
anyhow,
for the simple reason that per-vertex operations no longer mesh
well with
a modern graphics architecture.
If you are not writing a modern OpenGL app, then by all means, use
the
old version. It's going to be a while I think before cards drop
support
OpenGL 2 and earlier features. It will happen eventually though.
There are significant maintenance advantages to ctypes over C-
wrappers,
generated by SWIG or otherwise. It is difficult to make the latter
work
well across platforms and python versions. If you've ever looked at
the
build system for PyOpenGL 2.x, you'd understand what I mean. And
this is
coming from somebody who enjoys writing C extensions, but for
wrapping
existing APIs, ctypes is the state of the art. Like Python itself it
trades execution speed for development efficiency and better
portability.
PyOpenGL is more or less a one man project afaik, and let me tell
you,
development efficiency rules when you're trying to move mountains
yourself.
-Casey
On Mar 17, 2009, at 7:37 PM, Richie Ward wrote:
why did they not make 3.0 with swig?
On Tue, Mar 17, 2009 at 12:26 PM, RB[0] <roebros@xxxxxxxxx> wrote:
http://groups.google.com/group/pyglet-users/msg/832b15389fccd28d?
pli=1
Hmm, this is a bit outdated, but I found a few other references
that
say
SWIG will generally be faster to run, though would have more
overhead - so I
dunno.
HTH
On Tue, Mar 17, 2009 at 7:17 AM, RB[0] <roebros@xxxxxxxxx> wrote:
I saw saw tests for performance between the old C PyOpenGL and the
new
ctypes one...
The older one was significantly faster from what I saw - but that
is how
it will always be - direct usage of a C lib is just like calling C
functions
and such - whereas ctypes you have to call a python function
(which may call
others) which will execute the C lib code...
I'll see if I can't find the page somewhere...
On Mon, Mar 16, 2009 at 3:44 PM, Brian Fisher
<brian@xxxxxxxxxxxxxxxxxxx>
wrote:
That's what PyOpenGL 2.0 was - a C extension instead of ctypes.
(made
with SWIG)
I actually still use PyOpenGL 2.0 for reasons other than
performance
(py2exe packaging) - I had to build it myself on windows for
Python 2.5, you
can get at an installer for it here:
http://thorbrian.com/pyopengl/builds.php
I've never performance tested the difference between it and 3.0
though -
is somebody else could do that, I'd love to see the results
On Mon, Mar 16, 2009 at 10:49 AM, Zack Schilling
<zack.schilling@xxxxxxxxx> wrote:
If someone did this and I could drop it in to my code, that
would be
very nice. But for right now, PyOpenGL is serving my needs just
fine. I can
use about 600 independently textured and animated sprites
onscreen, scaled
and rotated, without stressing a low-end system more than 40%.
On Mar 16, 2009, at 1:00 PM, Forrest Voight wrote:
Would writing a replacement for PyOpenGL in C instead of in
Python
with ctypes help? I think it really would ... PyOpenGL is
internally
pretty complex, sometimes when I get tracebacks the error is
5 or 6
levels into PyOpenGL. Even a C library that only implemented
the
common functions and relied on PyOpenGL for the constants and
functions that do complex things like handling strings would
probably
help a lot.
Another way to increase speed is to write an opengl
rendering engine
in C and call and make it available as a Python extension.
This is
a major speed boost, in particular for a large number of
iterations.
Iirc PyOpenGL bindings are generated, many times this is
suboptimal
code for what you're trying to do, writing the Python
extension in C
manually have been faster for me many times. This is indeed
true
if you put your iterations inside a C loop instead of
calling the
C function from Python many times.
--
Thanks, Richie Ward