On Fri, 2016-02-19 at 11:47 +0000, Neil Roberts wrote: > Iago Toral <ito...@igalia.com> writes: > > > I don't know much about this, but using shader_samples_identical > > should only give a benefit if we actually get identical samples, > > otherwise it means more work, right? I noticed that the test renders a > > quad with random colors for each vertex that will be interpolated > > across the region, so could it be that we are hitting few cases of > > identical samples? Shouldn't the results be expected to be better if > > we rendered a flat color instead? > > It should all be identical regardless of the color chosen because it is > doing per-pixel shading rather than per-sample which means the fragment > shader is only run once per pixel and the same value is written to all > of the samples. The only case where you get differing samples normally > is at the edges of a polygon where the single color is only written to a > few of the samples. > > In this case it is even more identical because the random color is set > on a uniform rather than a vertex so it is actually using the same color > for the whole framebuffer. However, it is rendered as two triangles > which might mean that along the diagonal of the framebuffer where the > two triangles meet there will be a polygon edge which means the hardware > might not recognise that these all the same color, but that should only > be a few pixels and probably won't affect the results very much.
You're right, I read through the test code too fast :) Iago _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
