<div class="gmail_quote">On Wed, Jul 21, 2010 at 3:54 PM, Keith Whitwell <<a href="mailto:keithw@vmware.com">keithw@vmware.com</a>> wrote: <blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> <div><div></div><div class="h5">On Wed, 2010-07-21 at 01:49 -0700, Marek Olšák wrote: > Hi, > > there is a new branch gallium-depth-clamp in the main repository which > implements ARB_depth_clamp in Gallium. Wine uses this extension to > disable clipping when it's requested from a D3D9 app, so it's an > important one. > > There is a new state "depth_clamp" in pipe_clip_state, and a new cap > PIPE_CAP_DEPTH_CLAMP. If you think this feature should be mandatory in > Gallium instead, it's ok with me. There are several reasons I put the > enable bit in pipe_clip_state, but the most important one is that Z > clipping must be disabled in hardware first for it to work. It also > implements depth_clamp handling in cso_cache and wires up > ARB_depth_clamp in st/mesa. > > The support in Draw has also been implemented, and both softpipe and > llvmpipe pass piglit/depth_clamp and piglit/depth-clamp-range. > > <a href="http://cgit.freedesktop.org/mesa/mesa/log/?h=gallium-depth-clamp" target="_blank">http://cgit.freedesktop.org/mesa/mesa/log/?h=gallium-depth-clamp</a> > > Please review. > > -Marek </div></div>Marek, This looks like a useful change. I'm not sure it's actually going go give the expected results for softpipe/llvmpipe or other users of the path you've put into the draw module. In particular it looks like the spec calls for clamping depth on a per-pixel basis, where as this is doing it per-vertex. The difference is that the spec would allow a triangle with one distant vertex to hit the far plane and then be clamped to it, whereas your change means that the triangle as a whole will be altered to be in front of the depth plane and touch it at one vertex. Basically, I think the draw change needs to reduced to just disabling depth clipping, and (if you like) a clamp(depth, 0, 1) introduced into softpipe/llvmpipe. Or just don't advertise the cap for softpipe/llvmpipe. </blockquote><div> </div></div>You're absolutely right. Ok then, I've corrected the Draw changes and committed the patches without advertising the cap for software pipes. -Marek