On Wed, 2010-07-21 at 06:54 -0700, Keith Whitwell wrote: > 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. > > > > http://cgit.freedesktop.org/mesa/mesa/log/?h=gallium-depth-clamp > > > > Please review. > > > > -Marek > > > 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. > > Keith > > > > > > I would > > It adds an extra branch to the clipmask computation, but it's not like > that code is tuned at this point anyway... I'
Hmm, random thoughts... Just ignore, please. Keith :) _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
