[Piglit] [Mesa-dev] [RFC PATCH] arb_texture_barrier: call glTextureBarrier after each glDrawRangeElements

Nicolai Hähnle nhaehnle at gmail.com
Fri Jun 24 10:17:09 UTC 2016


Hi Alejandro,

my understanding of the spec is that the test should be correct as 
originally written, i.e. with glTextureBarrier only between full 
rectangle draws.

FWIW, radeonsi passes the test as-is (though I reduced the GLSL version 
requirement, which I'd ask you to change as well before you push the test).

Cheers,
Nicolai

On 24.06.2016 11:14, Alejandro Piñeiro wrote:
> Gets the test passing for cases with low resolution, high amount
> of triangles and more than one glDrawRangeElements (drawing_passes).
> ---
>
> Just to catch attention, this issue also affects the failing CTS test
> GL44-CTS.texture_barrier_ARB.same-texel-rw-multipass on Intel gen7+.
>
> And sorry for the cross-posting, but usually questions related about
> specs are more suited for mesa-dev.
>
> The test I have just sent to piglit list fails in the following scenario:
>    * Low resolution
>    * High amount of triangles on the square draw
>    * More than one glDrawRangeElements to render the square.
>
> As this patch shows, the problem gets solved if I move the
> glTextureBarrier call just after glDrawRangeElements, instead of
> having it after each full square drawn.
>
> But Im not sure if this should be needed if we strictly follow the
> spec. The spec [1] even include a example of when the barrier would
> not be needed on Issue 1. If what you are drawing doesn't intersect to
> what you have been drawing before, you don't need to call
> glTextureBarrier. Being strict, the test is drawing non intersecting
> elements, as the triangles are independent one from the other. But it
> is also true that this is somewhat debatable as the borders of the
> triangles are shared, so with low resolution and a high amount of
> triangles it can cause these artifacts.
>
> So, opinions? Is this patch correct so the problem was on the piglit
> test? Or this patch should not be needed so the problem is on the
> implementation of arb_texture_barrier?
>
> [1] https://www.opengl.org/registry/specs/ARB/texture_barrier.txt
>
>   tests/spec/arb_texture_barrier/blending-in-shader-arb.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/tests/spec/arb_texture_barrier/blending-in-shader-arb.c b/tests/spec/arb_texture_barrier/blending-in-shader-arb.c
> index 76822da..c84cfaf 100644
> --- a/tests/spec/arb_texture_barrier/blending-in-shader-arb.c
> +++ b/tests/spec/arb_texture_barrier/blending-in-shader-arb.c
> @@ -318,6 +318,7 @@ draw_rect_tex()
>
>                   glDrawRangeElements(GL_TRIANGLES, first, first + count, count,
>                                       GL_UNSIGNED_INT, BUFFER_OFFSET(first * sizeof(GLuint)));
> +                glTextureBarrier();
>                   first += count;
>           }
>   }
> @@ -330,8 +331,6 @@ piglit_display(void)
>           glViewport(0, 0, width, height);
>
>           for (i = 0; i < blend_passes; i++) {
> -                if (i != 0)
> -                        glTextureBarrier();
>                   draw_rect_tex();
>           }
>
>


More information about the Piglit mailing list