I don’t have direct access to the machine, debugging by proxy so it is a bit difficult. I was hoping this was a known problem, or at least get some ideas what to look out for.
Which ATI drivers? Is this with their latest 4.0 drivers? Or 3.3
3.3 iirc. I have reports of this happening on at least two different ATI hardware.
Hmmm. I presume you’re rendering shadows to an FBO which only has a depth attachment with ColorMask FALSE. Wonder if it’d magically start working if you add a dummy color attachment and set ColorMask TRUE. It’d be a bug, but just giving some ideas to nail down whether it’s a driver bug or not. Also what happens if you enable alpha test for your opaque casters?
I’d pop in a dummy frag shader that outputs opaque alpha and check for a difference.
Sounds plausible, good ideas. I will try these.
Which depth format are you targetting? If not 24, try 24.
16, though it is configurable by the user, I’d have to double-check. But I would assume that additional precision (24/32) should not cause far/nearplane clipping in cases where it doesn’t with 16-bit z-buffer precision?
There are no errors reported afaik, and none with FBO creation for sure.