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RE: [pygame] [Announce] Python bindings for the bitmask collision detection library
René Dudfield wrote:
> It's in pygame now.
>
> There's still a few things I need to do.
>
> - make constructor which takes a surface.
> - a 'make_surface' method in C. should take a threshold for alpha.
> - complete the documentation (now in src/mask.doc)
> - complete the unittests (test/test/mask_test.py)
> - make set_at and get_at raise IndexError when wrong index is given.
> - double check the reference counting.
> - integrate Mask into examples/testsprite.py
>
>
> JKrukoff has an idea about how to change the sprite classes so they
> can be extended to use different types of collision detection. He's
> going to write a proposal to the mailing list about it later.
Right, so as discussed in IRC, I have a simple proposal for extending the
sprite module collision detection routines to be able to handle arbitrary
types of collisions instead of only rect collisions. I propose adding a
callback parameter to spritecollide, groupcollide, and spritecollideany
which will be a function which evaluates two sprites for a collision,
returning a boolean result.
The default value for this parameter would be a function that uses
colliderect to evaluate the two sprites, giving clean backwards
compatibility with existing code.
I've had to write my own collision routines in order to support mixing
bounding boxes and bounding circles, but this method would allow for such
tests to be plugged into the existing API. This functionality currently
seems urgent, as we now need an optional way to use bitmask based
collisions. As long as it has to be extended, why not do so in a generic
way?
The attached file contains a sample implementation (sans documentation or
optimization work) which should illustrate the method. It also contains
basic collision functions for rect collisions, scaled rect collisions, and
circle collisions.
This method also lends itself to doing tests in stages, where a less
accurate and faster collision test is used first, and then the results are
used for a second pass with a more accurate (and slower) collision test.
Ex.
>>> import pygame.sprite as sprite
>>> a, b = pygame.sprite.Sprite( ), pygame.sprite.Sprite( )
>>> a.rect = pygame.rect.Rect( 0, 0, 10, 10 )
>>> b.rect = pygame.rect.Rect( 5, 5, 10, 10 )
>>> sprite.spritecollide( a, [ b ], False )
[<Sprite sprite(in 0 groups)>]
>>> sprite.spritecollide( a, [ b ], False, sprite.collide_rect )
[<Sprite sprite(in 0 groups)>]
>>> sprite.spritecollide( a, [ b ], False, sprite.collide_circle )
[<Sprite sprite(in 0 groups)>]
Admittedly, this doesn't solve the issue of how to generate masks for
bitmask collisions (though that can be worked around in the collision
function much as radius calculations are in collide_circle), but then the
default implementation doesn't provide a rect either. This is, I think, a
change in spirit with the current sprite implementation of an extensible
container.
There are some performance considerations, as this adds a couple of lookups
and a function call to each test, but honestly, if you're worried about
performance you aren't using the default collision functions anyway.
---------
John Krukoff
helot@xxxxxxxxxxx
## pygame - Python Game Library
## Copyright (C) 2000-2003 Pete Shinners
## (C) 2004 Joe Wreschnig
## 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
## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
##
## Pete Shinners
## pete@xxxxxxxxxxxx
"""
This module contains a base class for sprite objects. Also
several different group classes you can use to store and
identify the sprites. Some of the groups can be used to
draw the sprites they contain. Lastly there are a handful
of collision detection functions to help you quickly find
intersecting sprites in a group.
The way the groups are designed, it is very efficient at
adding and removing sprites from groups. This makes the
groups a perfect use for cataloging or tagging different
sprites. instead of keeping an identifier or type as a
member of a sprite class, just store the sprite in a
different set of groups. this ends up being a much better
way to loop through, find, and effect different sprites.
It is also a very quick to test if a sprite is contained
in a given group.
You can manage the relationship between groups and sprites
from both the groups and the actual sprite classes. Both
have add() and remove() functions that let you add sprites
to groups and groups to sprites. Both have initializing
functions that can accept a list of containers or sprites.
The methods to add and remove sprites from groups are
smart enough to not delete sprites that aren't already part
of a group, and not add sprites to a group if it already
exists. You may also pass a sequence of sprites or groups
to these functions and each one will be used.
While it is possible to design sprite and group classes
that don't derive from the Sprite and AbstractGroup classes
below, it is strongly recommended that you extend those
when you add a Sprite or Group class.
"""
##todo
## a group that holds only the 'n' most recent elements.
## sort of like the GroupSingle class, but holding more
## than one sprite
##
## drawing groups that can 'automatically' store the area
## underneath, so the can "clear" without needing a background
## function. obviously a little slower than normal, but nice
## to use in many situations. (also remember it must "clear"
## in the reverse order that it draws :])
##
## the drawing groups should also be able to take a background
## function, instead of just a background surface. the function
## would take a surface and a rectangle on that surface to erase.
##
## perhaps more types of collision functions? the current two
## should handle just about every need, but perhaps more optimized
## specific ones that aren't quite so general but fit into common
## specialized cases.
class Sprite(object):
"""The base class for your visible game objects.
The sprite class is meant to be used as a base class
for the objects in your game. It just provides functions
to maintain itself in different groups.
You can initialize a sprite by passing it a group or sequence
of groups to be contained in.
When you subclass Sprite, you must call this
pygame.sprite.Sprite.__init__(self) before you add the sprite
to any groups, or you will get an error."""
def __init__(self, *groups):
self.__g = {} # The groups the sprite is in
if groups: self.add(groups)
def add(self, *groups):
"""add(group or list of of groups, ...)
add a sprite to container
Add the sprite to a group or sequence of groups."""
has = self.__g.has_key
for group in groups:
if hasattr(group, '_spritegroup'):
if not has(group):
group.add_internal(self)
self.add_internal(group)
else: self.add(*group)
def remove(self, *groups):
"""remove(group or list of groups, ...)
remove a sprite from container
Remove the sprite from a group or sequence of groups."""
has = self.__g.has_key
for group in groups:
if hasattr(group, '_spritegroup'):
if has(group):
group.remove_internal(self)
self.remove_internal(group)
else: self.remove(*group)
def add_internal(self, group):
self.__g[group] = 0
def remove_internal(self, group):
del self.__g[group]
def update(self, *args):
pass
def kill(self):
"""kill()
remove this sprite from all groups
Removes the sprite from all the groups that contain
it. The sprite still exists after calling this,
so you could use it to remove a sprite from all groups,
and then add it to some other groups."""
for c in self.__g.keys():
c.remove_internal(self)
self.__g.clear()
def groups(self):
"""groups() -> list of groups
list used sprite containers
Returns a list of all the groups that contain this
sprite. These are not returned in any meaningful order."""
return self.__g.keys()
def alive(self):
"""alive() -> bool
check to see if the sprite is in any groups
Returns true if this sprite is a member of any groups."""
return (len(self.__g) != 0)
def __repr__(self):
return "<%s sprite(in %d groups)>" % (self.__class__.__name__, len(self.__g))
class AbstractGroup(object):
"""A base for containers for sprites. It does everything
needed to behave as a normal group. You can easily inherit
a new group class from this, or the other groups below,
if you want to add more features.
Any AbstractGroup-derived sprite groups act like sequences,
and support iteration, len, and so on."""
# dummy val to identify sprite groups, and avoid infinite recursion.
_spritegroup = True
def __init__(self):
self.spritedict = {}
self.lostsprites = []
def sprites(self):
"""sprites()
get a list of sprites in the group
Returns an object that can be looped over with a 'for' loop.
(For now it is always a list, but newer version of Python
could return different iterators.) You can also iterate directly
over the sprite group."""
return self.spritedict.keys()
def add_internal(self, sprite):
self.spritedict[sprite] = 0
def remove_internal(self, sprite):
r = self.spritedict[sprite]
if r is not 0:
self.lostsprites.append(r)
del(self.spritedict[sprite])
def has_internal(self, sprite):
return self.spritedict.has_key(sprite)
def copy(self):
"""copy()
copy a group with all the same sprites
Returns a copy of the group that is the same class
type, and has the same sprites in it."""
return self.__class__(self.sprites())
def __iter__(self):
return iter(self.sprites())
def __contains__(self, sprite):
return self.has(sprite)
def add(self, *sprites):
"""add(sprite, list, or group, ...)
add sprite to group
Add a sprite or sequence of sprites to a group."""
for sprite in sprites:
# It's possible that some sprite is also an iterator.
# If this is the case, we should add the sprite itself,
# and not the objects it iterates over.
if isinstance(sprite, Sprite):
if not self.has_internal(sprite):
self.add_internal(sprite)
sprite.add_internal(self)
else:
try:
# See if sprite is an iterator, like a list or sprite
# group.
for spr in sprite:
self.add(spr)
except (TypeError, AttributeError):
# Not iterable, this is probably a sprite that happens
# to not subclass Sprite. Alternately, it could be an
# old-style sprite group.
if hasattr(sprite, '_spritegroup'):
for spr in sprite.sprites():
if not self.has_internal(spr):
self.add_internal(spr)
spr.add_internal(self)
elif not self.has_internal(sprite):
self.add_internal(sprite)
sprite.add_internal(self)
def remove(self, *sprites):
"""remove(sprite, list, or group, ...)
remove sprite from group
Remove a sprite or sequence of sprites from a group."""
# This function behaves essentially the same as Group.add.
# Check for Spritehood, check for iterability, check for
# old-style sprite group, and fall back to assuming
# spritehood.
for sprite in sprites:
if isinstance(sprite, Sprite):
if self.has_internal(sprite):
self.remove_internal(sprite)
sprite.remove_internal(self)
else:
try:
for spr in sprite: self.remove(spr)
except (TypeError, AttributeError):
if hasattr(sprite, '_spritegroup'):
for spr in sprite.sprites():
if self.has_internal(spr):
self.remove_internal(spr)
spr.remove_internal(self)
elif self.has_internal(sprite):
self.remove_internal(sprite)
sprite.remove_internal(self)
def has(self, *sprites):
"""has(sprite or group, ...)
ask if group has a sprite or sprites
Returns true if the given sprite or sprites are
contained in the group. You can also use 'sprite in group'
or 'subgroup in group'."""
# Again, this follows the basic pattern of Group.add and
# Group.remove.
for sprite in sprites:
if isinstance(sprite, Sprite):
return self.has_internal(sprite)
try:
for spr in sprite:
if not self.has(spr):
return False
return True
except (TypeError, AttributeError):
if hasattr(sprite, '_spritegroup'):
for spr in sprite.sprites():
if not self.has_internal(spr):
return False
return True
else:
return self.has_internal(sprite)
def update(self, *args):
"""update(*args)
call update for all member sprites
calls the update method for all sprites in the group.
Passes all arguments on to the Sprite update function."""
for s in self.sprites(): s.update(*args)
def draw(self, surface):
"""draw(surface)
draw all sprites onto the surface
Draws all the sprites onto the given surface."""
sprites = self.sprites()
surface_blit = surface.blit
for spr in sprites:
self.spritedict[spr] = surface_blit(spr.image, spr.rect)
self.lostsprites = []
def clear(self, surface, bgd):
"""clear(surface, bgd)
erase the previous position of all sprites
Clears the area of all drawn sprites. the bgd
argument should be Surface which is the same
dimensions as the surface. The bgd can also be
a function which gets called with the passed
surface and the area to be cleared."""
if callable(bgd):
for r in self.lostsprites:
bgd(surface, r)
for r in self.spritedict.values():
if r is not 0: bgd(surface, r)
else:
surface_blit = surface.blit
for r in self.lostsprites:
surface_blit(bgd, r, r)
for r in self.spritedict.values():
if r is not 0: surface_blit(bgd, r, r)
def empty(self):
"""empty()
remove all sprites
Removes all the sprites from the group."""
for s in self.sprites():
self.remove_internal(s)
s.remove_internal(self)
def __nonzero__(self):
return (len(self.sprites()) != 0)
def __len__(self):
"""len(group)
number of sprites in group
Returns the number of sprites contained in the group."""
return len(self.sprites())
def __repr__(self):
return "<%s(%d sprites)>" % (self.__class__.__name__, len(self))
class Group(AbstractGroup):
"""The basic Group class you will want to use.
It supports all of the above operations and methods.
The RenderPlain and RenderClear groups are aliases to Group
for compatibility."""
def __init__(self, *sprites):
AbstractGroup.__init__(self)
self.add(*sprites)
RenderPlain = Group
RenderClear = Group
class RenderUpdates(Group):
"""A sprite group that's more efficient at updating.
This group supports drawing to the screen, but its draw method
also returns a list of the Rects updated by the draw (and any
clears in between the last draw and the current one). You
can use pygame.display.update(renderupdates_group.draw(screen))
to minimize the updated part of the screen. This can usually
make things much faster."""
def draw(self, surface):
spritedict = self.spritedict
surface_blit = surface.blit
dirty = self.lostsprites
self.lostsprites = []
dirty_append = dirty.append
for s in self.sprites():
r = spritedict[s]
newrect = surface_blit(s.image, s.rect)
if r is 0:
dirty_append(newrect)
else:
if newrect.colliderect(r):
dirty_append(newrect.union(r))
else:
dirty_append(newrect)
dirty_append(r)
spritedict[s] = newrect
return dirty
class OrderedUpdates(RenderUpdates):
"""RenderUpdates, but the sprites are drawn in the order they were added.
More recently added sprites are drawn last (and so, above other
sprites)."""
def __init__(self, *sprites):
self._spritelist = []
RenderUpdates.__init__(self, *sprites)
def sprites(self): return list(self._spritelist)
def add_internal(self, sprite):
RenderUpdates.add_internal(self, sprite)
self._spritelist.append(sprite)
def remove_internal(self, sprite):
RenderUpdates.remove_internal(self, sprite)
self._spritelist.remove(sprite)
class GroupSingle(AbstractGroup):
"""A group container that holds a single most recent item.
This class works just like a regular group, but it only
keeps a single sprite in the group. Whatever sprite has
been added to the group last, will be the only sprite in
the group.
You can access its one sprite as the .sprite attribute.
Assigning to this attribute will properly remove the old
sprite and then add the new one."""
def __init__(self, sprite = None):
AbstractGroup.__init__(self)
self.__sprite = None
if sprite is not None: self.add(sprite)
def copy(self):
return GroupSingle(self.__sprite)
def sprites(self):
if self.__sprite is not None: return [self.__sprite]
else: return []
def add_internal(self, sprite):
if self.__sprite is not None:
self.__sprite.remove_internal(self)
self.__sprite = sprite
def __nonzero__(self): return (self.__sprite is not None)
def _get_sprite(self):
return self.__sprite
def _set_sprite(self, sprite):
self.add_internal(sprite)
sprite.add_internal(self)
return sprite
sprite = property(_get_sprite, _set_sprite, None,
"The sprite contained in this group")
def remove_internal(self, sprite):
if sprite is self.__sprite: self.__sprite = None
def has_internal(self, sprite):
return (self.__sprite is sprite)
# Optimizations...
def __contains__(self, sprite): return (self.__sprite is sprite)
def collide_rect( left, right ):
return left.rect.colliderect( right.rect )
class collide_rect_ratio:
def __init__( self, ratio ):
self.ratio = ratio
def __inflate_by_ratio( self, rect ):
width = rect.width * self.ratio
height = rect.height * self.ratio
return rect.inflate( width - rect.width, height - rect.height )
def __call__( self, left, right ):
leftrect = self.__inflate_by_ratio( left.rect )
rightrect = self.__inflate_by_ratio( right.rect )
return leftrect.colliderect( rightrect )
def collide_circle( left, right ):
def get_radius_squared( sprite ):
try:
radiusSquared = sprite.radius ** 2
except AttributeError:
rect = sprite.rect
radiusSquared = ( rect.width ** 2 + rect.height ** 2 ) / 4
return radiusSquared
xDistance = left.rect.centerx - right.rect.centerx
yDistance = left.rect.centery - right.rect.centery
distanceSquared = xDistance ** 2 + yDistance ** 2
return distanceSquared < get_radius_squared( left ) + get_radius_squared( right )
def spritecollide(sprite, group, dokill, collided = collide_rect):
"""pygame.sprite.spritecollide(sprite, group, dokill) -> list
collision detection between sprite and group
given a sprite and a group of sprites, this will
return a list of all the sprites that intersect
the given sprite.
all sprites must have a "rect" value, which is a
rectangle of the sprite area. if the dokill argument
is true, the sprites that do collide will be
automatically removed from all groups."""
crashed = []
if dokill:
for s in group.sprites():
if collided( sprite, s ):
s.kill()
crashed.append(s)
else:
for s in group:
if collided( sprite, s ):
crashed.append(s)
return crashed
def groupcollide(groupa, groupb, dokilla, dokillb, collided = collide_rect):
"""pygame.sprite.groupcollide(groupa, groupb, dokilla, dokillb) -> dict
collision detection between group and group
given two groups, this will find the intersections
between all sprites in each group. it returns a
dictionary of all sprites in the first group that
collide. the value for each item in the dictionary
is a list of the sprites in the second group it
collides with. the two dokill arguments control if
the sprites from either group will be automatically
removed from all groups."""
crashed = {}
SC = spritecollide
if dokilla:
for s in groupa.sprites():
c = SC(s, groupb, dokillb, collided)
if c:
crashed[s] = c
s.kill()
else:
for s in groupa:
c = SC(s, groupb, dokillb, collided)
if c:
crashed[s] = c
return crashed
def spritecollideany(sprite, group, collided = collide_rect):
"""pygame.sprite.spritecollideany(sprite, group) -> sprite
finds any sprites that collide
given a sprite and a group of sprites, this will
return return any single sprite that collides with
with the given sprite. If there are no collisions
this returns None.
if you don't need all the features of the
spritecollide function, this function will be a
bit quicker.
all sprites must have a "rect" value, which is a
rectangle of the sprite area."""
for s in group:
if collided( sprite, s ):
return s
return None