[Mesa-dev] [PATCH 2/2] u_blitter: Add an option to draw the triangles using an index buffer.

[Marek Olšák]

For the series:

Reviewed-by: Marek Olšák <marek.olsak at amd.com>

Marek

On Wed, Jul 11, 2018 at 6:05 PM, Eric Anholt <eric at anholt.net> wrote:
> For V3D, the HW will interpolate slightly differently along the shared
> edge of the trifan.  The conformance tests manage to catch this in the
> nearest_consistency_* group.  To get interpolation to match, we need the
> last vertex of the triangle to be shared.
>
> I first tried implementing draw_rectangle to do triangles instead, but
> that was quite a bit (147 lines) of code duplication from u_blitter, and
> this seems much simpler and less likely to break as u_blitter changes.
>
> Fixes dEQP-GLES3.functional.fbo.blit.rect.nearest_consistency_* on V3D.
> ---
>  src/gallium/auxiliary/util/u_blitter.c | 16 ++++++++++++++--
>  src/gallium/auxiliary/util/u_blitter.h |  2 ++
>  src/gallium/drivers/v3d/v3d_context.c  |  1 +
>  3 files changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/src/gallium/auxiliary/util/u_blitter.c b/src/gallium/auxiliary/util/u_blitter.c
> index 4748627fc523..eadb76a109fb 100644
> --- a/src/gallium/auxiliary/util/u_blitter.c
> +++ b/src/gallium/auxiliary/util/u_blitter.c
> @@ -1258,8 +1258,20 @@ static void blitter_draw(struct blitter_context_priv *ctx,
>     pipe->set_vertex_buffers(pipe, ctx->base.vb_slot, 1, &vb);
>     pipe->bind_vertex_elements_state(pipe, vertex_elements_cso);
>     pipe->bind_vs_state(pipe, get_vs(&ctx->base));
> -   util_draw_arrays_instanced(pipe, PIPE_PRIM_TRIANGLE_FAN, 0, 4,
> -                              0, num_instances);
> +
> +   if (ctx->base.use_index_buffer) {
> +      /* Note that for V3D,
> +       * dEQP-GLES3.functional.fbo.blit.rect.nearest_consistency_* require
> +       * that the last vert of the two tris be the same.
> +       */
> +      static uint8_t indices[6] = { 0, 1, 2, 0, 3, 2 };
> +      util_draw_elements_instanced(pipe, indices, 1, 0,
> +                                   PIPE_PRIM_TRIANGLES, 0, 6,
> +                                   0, num_instances);
> +   } else {
> +      util_draw_arrays_instanced(pipe, PIPE_PRIM_TRIANGLE_FAN, 0, 4,
> +                                 0, num_instances);
> +   }
>     pipe_resource_reference(&vb.buffer.resource, NULL);
>  }
>
> diff --git a/src/gallium/auxiliary/util/u_blitter.h b/src/gallium/auxiliary/util/u_blitter.h
> index 9e945983baac..9ea1dc9b6b28 100644
> --- a/src/gallium/auxiliary/util/u_blitter.h
> +++ b/src/gallium/auxiliary/util/u_blitter.h
> @@ -100,6 +100,8 @@ struct blitter_context
>     /* Whether the blitter is running. */
>     bool running;
>
> +   bool use_index_buffer;
> +
>     /* Private members, really. */
>     struct pipe_context *pipe; /**< pipe context */
>
> diff --git a/src/gallium/drivers/v3d/v3d_context.c b/src/gallium/drivers/v3d/v3d_context.c
> index cef32ceb069d..6fb807b1aa8a 100644
> --- a/src/gallium/drivers/v3d/v3d_context.c
> +++ b/src/gallium/drivers/v3d/v3d_context.c
> @@ -164,6 +164,7 @@ v3d_context_create(struct pipe_screen *pscreen, void *priv, unsigned flags)
>          v3d->blitter = util_blitter_create(pctx);
>          if (!v3d->blitter)
>                  goto fail;
> +        v3d->blitter->use_index_buffer = true;
>
>          v3d->primconvert = util_primconvert_create(pctx,
>                                                     (1 << PIPE_PRIM_QUADS) - 1);
> --
> 2.18.0
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/mesa-dev