Hello, I'm wondering what exactly are the conditions on modern GPUs (e.g. GeForce 8800) for early-Z to be enabled. All I found on the web are some hints that something has been improved... It seems to me early-Z gets disabled when you're discarding fragments or modifying depth on pixel shader, but, are there some other conditions as well? What I'd need to do is to "carve out" parts of triangles, i.e., make certain fragments invisible/transparent (in order to render nice silhouettes), but still retain early-Z, as my pixel shader will be rather heavy. Deferred shading is of no help as the actual shading is trivial (the problem is in the carving -- it's something like relief mapping, but that's not important here I guess). Any suggestions?

Quote:Original post by ladzin
It seems to me early-Z gets disabled when you're discarding fragments or modifying depth on pixel shader

More the latter than the former. Good info here. BTW, alpha testing certainly won't disable early Z culling, and it sounds like that's what you're trying to do.

regarding both early-z and z-cull; what happens if you do a depth pre-pass (as in something like crysis does; render only the depth to a depth buffer and also write the depth to a render target)?

Would doing a depth pre-pass allow you to safely use texkill, alpha testing, ect, in the color pass (with depth writing disabled) without disabling early z and z cull?