Cocos2D collision detection of CCSprites on different CCNodes with different position and rotation

Question

I have a hierarchy like this:

Scene
 - gameWorld (CCLayer Z:0)
    - player (CCSprite Z:1)
 - spriteWorld (CCNode Z:0)
    - bgSprite (CCSprite Z:0)
       - enemy (CCSprite Z:0)

The spriteWorld gets rotated and the bgSprite gets moved around so any CCSprites placed on bgSprite has a rotated and moved coordinate system compared to the gameWorld coordinate system.

I need to detected collisions between CCSprites placed both on the gameWorld and bgSprite. Now I have seen this post here:

Cocos2D CCNode position in absolute screen coordinates

which can give me each sprites position relative to the screen, but how do I then calculate or get the bounding box for these sprites? Those bounding boxes are rotate both via the spriteWorld rotation but each sprite also rotates on the bgSprite.

Sounds like a lot of crazy math to me and I am a fool at math, so I really really need help here.

Thank you Særen

Answer 1

Indeed, cocos2D has no direct support for collision detection, so you would need to do all your calculations on your own.

Anyway, you can use a framework like chipmunk-physics or Box2D to do that for you. The basic idea is that you associate a body/shape to your sprite and then setup a collision callback that will be fired when the collision is detected, without worrying about the math...

Have a look at this article about using Box2D just for collision detection.