Cocos2D CCNode position in absolute screen coordinates

I’ve been looking around for a while, and I have not been able to find an answer to this for some reason. It seems simple enough, but maybe I just can’t find the right function in the library.

I have a scene with a layer that contains a bunch of CCNodes with each one CCSprite in them.

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  • During the application, I move around the position of the main layer, so that I “pan” around a camera in a way. (i.e. I translate the entire layer so that the viewport changes).

    Now I want to determine the absolute position of a CCNode in screen coordinates. The position property return the position relative to the parent node, but I really would like this transformed to its actual position on screen.

    Also, as an added bonus, it would be awesome if I could express this position as coordinate system where 0,0 maps to the upper left of the screen, and 1,1 maps to the lower right of the screen. (So I stay compatible with all devices)

    Edit: Note that the solution should work for any hierarchy of CCNodes preferably.

    Solutions Collect From Internet About “Cocos2D CCNode position in absolute screen coordinates”

    Every CCNode, and descendants thereof, has a method named convertToWorldSpace:(CGPoint)p

    This returns the coordinates relative to your scene.

    When you have this coordinate, flip your Y-axis, as you want 0,0 to be in the top left.

    CCNode * myNode = [[CCNode alloc] init];
    myNode.position = CGPointMake(150.0f, 100.0f);
    CCSprite * mySprite = [[CCSprite alloc] init]; // CCSprite is a descendant of CCNode
    [myNode addChild: mySprite];
    mySprite.position = CGPointMake(-50.0f, 50.0f);
    // we now have a node with a sprite in in. On this sprite (well, maybe
    // it you should attack the node to a scene) you can call convertToWorldSpace:
    CGPoint worldCoord = [mySprite convertToWorldSpace: mySprite.position];
    // to convert it to Y0 = top we should take the Y of the screen, and subtract the worldCoord Y
    worldCoord = CGPointMake(worldCoord.x, ((CGSize)[[CCDirector sharedDirector] displaySizeInPixels]).height - worldCoord.y);
    // This is dry coded so may contain an error here or there.
    // Let me know if this doesn't work.
    [mySprite release];
    [myNode release];