<div dir="ltr"> <div class="gmail_extra"> <div class="gmail_quote">On Wed, Sep 14, 2016 at 1:29 PM, Anuj Phogat <<a href="mailto:anuj.phogat@gmail.com" target="_blank">anuj.phogat@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Wed, Sep 14, 2016 at 10:45 AM, Jason Ekstrand <<a href="mailto:jason@jlekstrand.net">jason@jlekstrand.net</a>> wrote: > From the ARB_gpu_shader5 spec: > > The built-in functions interpolateAtCentroid() and interpolateAtSample() > will sample variables as though they were declared with the "centroid" > or "sample" qualifiers, respectively. > > When running with persample dispatch forced by the API, we interpolate > anything that isn't flat as if it's qualified by "sample". In order to > keep interpolateAtCentroid() consistent with the "centroid" qualifier, we > need to make interpolateAtCentroid() do sample interpolation instead. > Nothing in the GLSL spec guarantees that the result of > interpolateAtCentroid is uniform across samples in any way, so this is a > perfectly fine thing to do. > This explanation sounds good to me. To be consistent with what we do in case of per sample interpolation, shouldn't we do sample interpolation in case of InterpolateAtOffset() too? This series doesn't seem to include it. </blockquote><div> </div><div>No. interpolateAtOffset ask that the input be interpolated at a particular offset relative to the pixel center. I believe we have to respect that. </div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5"> > Fixes 8 of the new dEQP-VK.pipeline.multisample_interpolation.* Vulkan CTS > tests that specifically validate consistency between the "sample" qualifier > and interpolateAtSample() > > Signed-off-by: Jason Ekstrand <<a href="mailto:jason@jlekstrand.net">jason@jlekstrand.net</a>> > --- > src/mesa/drivers/dri/i965/brw_fs.cpp | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp > index 75642d3..9dbb699 100644 > --- a/src/mesa/drivers/dri/i965/brw_fs.cpp > +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp > @@ -6497,6 +6497,32 @@ brw_nir_set_default_interpolation(const struct gen_device_info *devinfo, > var->data.sample = false; > } > } > + > + if (per_sample_interpolation) { > + nir_foreach_block(block, nir_shader_get_entrypoint(nir)) { > + nir_foreach_instr(instr, block) { > + if (instr->type != nir_instr_type_intrinsic) > + continue; > + > + nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr); > + if (intrin->intrinsic != nir_intrinsic_interp_var_at_centroid) > + continue; > + > + nir_variable *var = intrin->variables[0]->var; > + if (var->data.interpolation == INTERP_MODE_FLAT) > + continue; > + > + /* The description of the interpolateAtCentroid intrinsic is that > + * it interpolates the variable as if it had the "centroid" > + * qualifier. When executing with per_sample_interpolation, this > + * is equivalent to having the "sample" qualifier. Just convert > + * it to a load_var instead. > + */ > + assert(var->data.sample); > + intrin->intrinsic = nir_intrinsic_load_var; > + } > + } > + } > } > > /** > -- > 2.5.0.400.gff86faf > </div></div>> _______________________________________________ > mesa-dev mailing list > <a href="mailto:mesa-dev@lists.freedesktop.org">mesa-dev@lists.freedesktop.org</a> > <a href="https://lists.freedesktop.org/mailman/listinfo/mesa-dev" rel="noreferrer" target="_blank">https://lists.freedesktop.org/mailman/listinfo/mesa-dev</a> </blockquote></div> </div></div>