Parent coordinate given a CCNode local coordinate

Question

Is there any cocos2d function that returns the parent coordinate given a node local coordinate? It must be quite a common use case, but I've not found any native cocos2d function. Is there any?

I guess it's something like this. NOTE, I haven't tested this one. ;)

-(CGPoint) nodeToParent: (CGPoint) localPoint
{
  CGFloat phi = -self.rotation * B2_pi / 180;
  return ccpAdd(self.position, ccpRotateByAngle(localPoint, ccp(0, 0), phi));
}

Answer 1

As m.ding said ... parent->ConvertToNodeSpace() .....

Here's explanation for you so you know when to do what ?

convertToWorldSpace(const CCPoint& nodePoint) converts on-node coords to SCREEN coordinates. Lets we have layerA with anchor point and position (0,0) attached to screen and have a sprite on this layer at point (100, 100). What will be SCREEN coords of sprite? - (100, 100)

Lets we moved layerA to point (- 50, - 20). What will be SCREEN coords of sprite? - (100 - 50, 100 - 20), i.e. (50, 80) - that's what convertToWorldSpace returns to us if we call layerA->convertToWorldSpace(ccp(100, 100)).

As for convertToWorldSpaceAR - will return the position relatevely to anchor point: so if our scene - root layer has AP (0.5f, 0.5f) - default, convertToWorldSpaceAR should return position relatively to screen center. I have used convertToNodeSpace

convertToNodeSpace(const CCPoint& worldPoint) - converts SCREEN coords to NODE's local. I.e. if for our example with moved layer call: layerA->convertToNodeSpace(ccp(50, 80)) - that should return (100, 100) - our sprite on-node coords.

convertToNodeSpaceAR - the same logic as for convertToWorldSpaceAR