On 2 July 2012 13:45, Vadim Girlin <vadimgir...@gmail.com> wrote: > On Mon, 2012-07-02 at 10:08 -0700, Paul Berry wrote: > > On 2 July 2012 08:04, Vadim Girlin <vadimgir...@gmail.com> wrote: > > On Sun, 2012-06-24 at 11:18 +0200, Olivier Galibert wrote: > > > That old bug was hidden but the clipper always interpolating > > in 3d > > > space no matter what it should have been doing. Now that > > the > > > interpolation has been fixed, the bug shows up. > > > > > > Fixes bugzilla 51364. > > > > > > Signed-off-by: Olivier Galibert <galib...@pobox.com> > > > > > > diff --git a/src/mesa/state_tracker/st_program.c > > b/src/mesa/state_tracker/st_program.c > > > index e6664fb..9f98298 100644 > > > --- a/src/mesa/state_tracker/st_program.c > > > +++ b/src/mesa/state_tracker/st_program.c > > > @@ -569,12 +569,12 @@ st_translate_fragment_program(struct > > st_context *st, > > > case FRAG_ATTRIB_CLIP_DIST0: > > > input_semantic_name[slot] = > > TGSI_SEMANTIC_CLIPDIST; > > > input_semantic_index[slot] = 0; > > > - interpMode[slot] = TGSI_INTERPOLATE_LINEAR; > > > + interpMode[slot] = > > TGSI_INTERPOLATE_PERSPECTIVE; > > > break; > > > case FRAG_ATTRIB_CLIP_DIST1: > > > input_semantic_name[slot] = > > TGSI_SEMANTIC_CLIPDIST; > > > input_semantic_index[slot] = 1; > > > - interpMode[slot] = TGSI_INTERPOLATE_LINEAR; > > > + interpMode[slot] = > > TGSI_INTERPOLATE_PERSPECTIVE; > > > > > > At first glance this change doesn't seem correct, GLSL 1.30 > > spec says > > that clip distances are interpolated linearly. Am I missing > > something? > > > > I think when the spec says "The clip distances will be linearly > > interpolated across the primitive...", they mean "linear in 3D space". > > Interpolating clip distances in screen space would produce really bad > > artifacts, IMHO. > > Looking into it, I think you are right, sorry for the noise. > > Though then I have some doubts about the "fs-clip-distance-interpolated" > test. AFAICS r600g in fact uses different interpolation for ClipDistance > inputs with and without the patch, but the test does pass in both > cases. >
Yeah, fs-clip-distance-interpolated only checks that the fragment shader sees properly interpolated values for gl_ClipDistance. It doesn't check that the implementation uses the correct form of interpolation to decide where to clip the primitive. I suspect that's the reason the test passes in both cases. I wasn't thinking carefully enough when I wrote the test to realize that these two things ought to be tested separately. If you would like to add a piglit test to cover the case I missed, I would be delighted :) > > Vadim > > > > > > > Vadim > > > > > break; > > > /* In most cases, there is nothing special > > about these > > > * inputs, so adopt a convention to use the > > generic > > > _______________________________________________ > > > mesa-dev mailing list > > > mesa-dev@lists.freedesktop.org > > > http://lists.freedesktop.org/mailman/listinfo/mesa-dev > > > > > > > > _______________________________________________ > > mesa-dev mailing list > > mesa-dev@lists.freedesktop.org > > http://lists.freedesktop.org/mailman/listinfo/mesa-dev > > > > > > > >
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