Since the concept was difficult to explain in words for someone who's not quite familiar with shader, I described it in pictures. I'm currently using Unity and it seems Shaderlab is the best choice ...
Tiled terrain. User wants to build a structure. He presses build and for each tile there is an "allow" or "disallow" tile sprite added to the scene. FPS drops right away, since there are 600+ tiles ...
I've been experimenting with Ray Wenderlich's tutorial about masking sprite using shaders with cocos2D 2.0. It works pretty well but now I'd like to rotate the mask independently of the masked ...