[Piglit] [PATCH] arb_fb_no_attach: add multisampling subtests

[Ilia Mirkin]

On Sun, Jan 31, 2016 at 1:28 AM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> Test both MS and per-sample shaded cases. With MS, there should be no
> additional invocations, while with per-sample shading, each sample
> should be counted.
>
> Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
> ---
>
> The "MS4" test fails for me on nvc0 for some reason... it ends up with a whole extra column's worth of counting added. No idea why... perhaps this is somehow permissible and happens as a result of the seam?

Thinking a bit more about this... it's exactly because of the seam.
Even without per-sample shading, at MS4 both triangles that make up
the quad end up covering at least one sample of the seam. So for a
square window, that's just an extra N items, but for other sizes it
may be harder to calculate, so I'm just going to skip it.

>
>  tests/spec/arb_framebuffer_no_attachments/atomic.c | 24 ++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>
> diff --git a/tests/spec/arb_framebuffer_no_attachments/atomic.c b/tests/spec/arb_framebuffer_no_attachments/atomic.c
> index 0c62ac3..553ff02 100644
> --- a/tests/spec/arb_framebuffer_no_attachments/atomic.c
> +++ b/tests/spec/arb_framebuffer_no_attachments/atomic.c
> @@ -157,6 +157,30 @@ piglit_init(int argc, char **argv)
>
>         pass &= compare_counter(4, "glViewport");
>
> +       /* Reset counter and add samples to the default fb */
> +       reset_counter();
> +       glViewport(0, 0, piglit_width, piglit_height);
> +       glFramebufferParameteri(GL_FRAMEBUFFER,
> +                               GL_FRAMEBUFFER_DEFAULT_SAMPLES, 4);
> +
> +       piglit_draw_rect(-1, -1, 2, 2);
> +
> +       pass &= compare_counter(piglit_width * piglit_height, "MS4");
> +
> +       if (piglit_is_extension_supported("GL_ARB_sample_shading")) {
> +               /* Reset counter and enable per-sample shading */
> +               reset_counter();
> +               glEnable(GL_SAMPLE_SHADING_ARB);
> +               glMinSampleShadingARB(1.0);
> +
> +               piglit_draw_rect(-1, -1, 2, 2);
> +
> +               pass &= compare_counter(piglit_width * piglit_height * 4,
> +                                       "Per-sample");
> +       } else {
> +               piglit_report_subtest_result(PIGLIT_SKIP, "Per-sample");
> +       }
> +
>         glDeleteFramebuffers(1, &fbo);
>         glDeleteVertexArrays(1, &vao);
>         glDeleteBuffers(1, &buffer);
> --
> 2.4.10
>