How to obtain zRotation of a sprite relative to world coordinates?

Question

For example if you have a rotated sprite, to which you add another rotated sprite, and so on. How would you determine the on-screen zRotation of a sub-sprite, or the "absolute" rotation of a sprite?

Answer 1

If I'm not grossly mistaken, it's simply the sum of all zRotation properties of the node and its parents (excluding the scene).

For example:

CGFloat absoluteRotation = self.zRotation + self.parent.zRotation;