[Piglit] [PATCH 12/18] arb_geometry_shader4: Test that adjacent vertices are ignored when no geometry shader is active.

Fabian Bieler fabianbieler at fastmail.fm
Mon Jun 17 02:40:10 PDT 2013

On 2013-06-17 06:46, Paul Berry wrote:
> On 24 May 2013 19:49, Fabian Bieler <fabianbieler at fastmail.fm <mailto:fabianbieler at fastmail.fm>> wrote:
>     +/**
>     + * \file ignore-adjacent-vertices-indexed.c
>     + *
>     + * Test that adjacent vertices are ignored when no geometry shader is active.
>     + * Draw the adjacency primitive in red and blend the non adjacency version in
>     + * green on top of it. Then test that the entire framebuffer is either yellow
>     + * or black.
> I really like this yellow/black idea.  Previously we have done this sort of test by drawing images on the left and right side of the window and then using piglit_probe_rect_halves_equal_rgba() to check that they're the same, but that has two problems: (1) sometimes rounding errors in the GPU cause slight variations between the two halves, which leads to false failures.  (2) when there are subtle differences between the left and right halves, it's difficult to spot the differences visually, making debugging hard.  Your yellow/black technique neatly addresses both of these problems.
Thanks, but I have to admit I took the idea from tests/general/triangle-rasterization.cpp which was written by James Benton.
> You might want to consider giving check_framebuffer() a more descriptive name and moving it into tests/util/piglit-util-gl-common.c so that it can be used by other tests.
I'll do that in a subsequent, separate test from this series.

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