Am 26.01.2010 um 19:23 schrieb Henri Verbeet: > On 26 January 2010 18:56, Stefan Dösinger <[email protected]> wrote: >> It would be interesting to see how D3DCMP_GREATER behaves with clipping off. >> Does the clamping occur before the depth test, or after the test but before >> writing the values into the depth buffer. (ie, is 3.0 > 1.0 or is 3.0 == 1.0) >> > It's not completely trivial to reliably test that due to precision > differences between the vertex data and the depth buffer Why? I'd expect that if you first draw something with depth clamping enabled with z=2(so it ends up at 1.0) then it really ends up at 1.0 and not 0.999998. If the Z buffer is cleared without drawing anything I'd expect it to contain an exact 1.0 as well. If there are precision problems in either situation I think the card/driver would be pretty broken.
> ARB_depth_buffer_float doesn't describe interactions with > ARB_depth_clamp, which might imply we'll have to disable depth > clamping for floating point depth buffers, but I doubt floating point > depth buffers are particularly useful without shaders anyway. Did you try depth clamping with shaders? Wrt vertex shaders I don't really expect surprises on either side, and wrt pixel shaders there are at least no surprises on the GL side(since we have that replacement pipeline and are using shaders anyway)
