Thanks for your kindly reply.
I don't konw this meaning.
So we have a progressive refinement with each pass, and already the first pass gives you results. It usually makes no sense to look for very deep layers
My question is that, I want a number of depth images to represents a scene. However, I don't know how much the layer number is. I hope to find a specific pass that tell me how many fragment N (also can be known as layers because 1 layer issues one fragment) in each pixel of final image (u,v). Thus by rendering Nmax number of scene, we can get Nmax depth images to briefly represent this scece.