cocos2d for iPhone

A fast, easy to use, free, and community supported 2D game engine

1. 

   jd
   Member

   Is this the proper way to remove a shape from chipmunk? It seems to work OK.
   

   -(void)cleanupShape:(cpShape*)s
   {
   	NSLog(@"cleanupShape");
   	cpSpaceRemoveBody(space, s->body);
   	cpBodyDestroy(s->body);
   	cpSpaceRemoveShape(space, s);
   	cpShapeDestroy(s);
   }

   I also remove the related sprite right after. Does this look right for a sprite with an action?
   

   AtlasSprite *a = [[AppDelegate get].enemyImages objectAtIndex:i];
           [[AppDelegate get].enemyImages removeObjectAtIndex:i];
   	[a stopAllActions];
   	[a removeAllChildrenWithCleanup:YES];
   	[self removeChild:a cleanup: YES];
   	[[TextureMgr sharedTextureMgr] removeUnusedTextures];

   Posted 2 years ago #
2. 

   jd
   Member

   I think I'm having an issue with chipmunk. I have a bunch of Enemies on the board at once. They are all the same collision group. When I kill one Enemy that is touching another Enemy, I get a EXC_BAD_ACCESS when I run the cleanupShape code above. Once in a while it will show me where in chipmunk the error is. I saw some code that looks like it checks whether two objects in space are in the same collision group and ignore them if they are. Well, if it goes to do that check while I remove one of the objects, I think that causes the error.

   If I run one enemy at a time, no error. If the Enemies are touching but not being removed, no error.

   Any chipmunk experts here that can chime in?

   Posted 2 years ago #
3. 

   jd
   Member

   Here is that code in chipmunk (cpSpace.c:347).
   

   static inline int
   queryReject(cpShape *a, cpShape *b)
   {
   	return
   		// BBoxes must overlap
   		!cpBBintersects(a->bb, b->bb)
   		// Don't collide shapes attached to the same body.
   		|| a->body == b->body
   		// Don't collide objects in the same non-zero group
   		|| (a->group && b->group && a->group == b->group)
   		// Don't collide objects that don't share at least on layer.
   		|| !(a->layers & b->layers);
   }

   Posted 2 years ago #
4. 

   coolman
   Member

   See this thread,

   http://groups.google.com/group/cocos2d-iphone-discuss/browse_thread/thread/c435ed120de9fb76/0b0909cede600310

   Posted 2 years ago #
5. 

   iisystems
   Member

   The last time I looked, the official released Chipmunk version does not support removing objects from the collision callbacks. I saw slembcke added support for this in a recent trunk, but I haven't tested it. What I do is mark the objects to be removed in the collision callbacks and then actually remove them as part of my step loop. No more access violations after this...

   Scott

   Posted 2 years ago #
6. 

   jd
   Member

   Can you post your removal code (sprite and space/body)? Maybe the order is important. I am doing what you are doing. In my callback I add candidates to an array. Then, I make sure I'm on the next step before attempting to remove. But I'm not sure I'm removing properly because the eachShape function is giving BAD_EXEC for some reason. I'm still debugging.

   Posted 2 years ago #
7. 

   jd
   Member

   I fixed my issue which was unrelated to chipmunk. I use arrays to store most of my objects. I was using the array index as a sprite tag so I could easily lookup the object in each array when necessary. When I had a collision, I removed the sprite by the tag. Two sprites (from two different arrays) had the same tag and were released. Therefore, when chipmunk looked for collisions next step it did not find a sprite that should be there.

   Although I lost plenty of time debugging and had several headaches, I learned more about cocos2d and chipmunk during the process.

   Posted 2 years ago #

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