cocos2d for iPhone

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

1. 

   Joe
   Member

   Can anybody please let me know how I can detect that an actor/body has left the world?

   This has been asked before, but there was no answer (http://www.cocos2d-iphone.org/forum/topic/2108).

   Is the b2BoundaryListener deprecated in the current version of box2d?

   tia

   Posted 2 years ago #
2. 

   riq
   Key Master

   yes, b2BoundaryListener is deprecated in Box2d v2.1
   You could use sensors + contact listeners instead.

   Posted 2 years ago #
3. 

   Joe
   Member

   Thanks riq. Is there any code example available? I haven't found anything in the Box2d testbed.

   Posted 2 years ago #
4. 

   riq
   Key Master

   search for isSensor or sensor in cocos2d/external/Box2d/TestBed/tests/

   and check collisions like if it were an standard box2d object.

   Posted 2 years ago #
5. 

   badawe
   Member

   If you wanna try a simple way you can do something like that at your step:

   if (b->GetPosition().y * PTM_RATIO < -10)
   				{
   					AtlasSprite *tempBox = (AtlasSprite *)b->GetUserData();
   					[asm removeChild:AtlasSprite];
                                           _world->DestroyBody(b);
   
   				}

   Posted 2 years ago #
6. 

   blackmouth
   Member

   Thanks Badawe,

   I was looking for a simple solution like this to remove Box2D AtlasSprite bodies.
   Your code helped me make this ,inside my Box2d world step.

   if (b->GetPosition().y * PTM_RATIO < -10)
       {
   	AtlasSprite *tempBox = (AtlasSprite *)b->GetUserData();
   	[[self _spriteManager] removeChild:tempBox cleanup:YES];
   	_world->DestroyBody(b);
       }

   I think it worked. :)

   Posted 2 years ago #
7. 

   onedayitwillmake
   Member

   Just a tiny note, on that one line:
   

   if (b->GetPosition().y * PTM_RATIO < -10)

   You'll want to check the radius of the object instead of -10.
   I'm sure badawe was just giving a generic example, but something to keep in mind.

   AtlasSprite* sprite = (AtlasSprite*) b->GetUserData();
   float objectRadiusInb2World = [sprite contentSize].width * sprite.scale / 2 / PTM_RATIO;
   
   // Now check
   if (b->GetPosition().y * PTM_RATIO < -objectRadiusInb2World)
       sprite._markForDeletion = YES;

   If you're deleting the body in the current loop, be sure you've already set you're 'b' pointer before it happened, otherwise the linked-list chain of bodies will be broken and your next iteration will crash.

   Oneday,
   http://littlephysics.com

   Posted 2 years ago #

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