[PATCH] glamor: Eliminate diagonal tearing in xv

[Alex Deucher]

On Mon, Jul 28, 2014 at 2:10 PM, Keith Packard <keithp at keithp.com> wrote:
> This uses a single large triangle and a scissor to draw the video
> instead of two triangles.
>
> Signed-off-by: Keith Packard <keithp at keithp.com>

Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  glamor/glamor_xv.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/glamor/glamor_xv.c b/glamor/glamor_xv.c
> index 68a06a4..3f3e064 100644
> --- a/glamor/glamor_xv.c
> +++ b/glamor/glamor_xv.c
> @@ -336,6 +336,7 @@ glamor_xv_render(glamor_port_private *port_priv)
>                            GL_FALSE, 2 * sizeof(float), vertices);
>
>      glEnableVertexAttribArray(GLAMOR_VERTEX_POS);
> +    glEnable(GL_SCISSOR_TEST);
>      for (i = 0; i < nBox; i++) {
>          float off_x = box[i].x1 - port_priv->drw_x;
>          float off_y = box[i].y1 - port_priv->drw_y;
> @@ -356,23 +357,25 @@ glamor_xv_render(glamor_port_private *port_priv)
>
>          glamor_set_normalize_vcoords(pixmap_priv,
>                                       dst_xscale, dst_yscale,
> -                                     dstx,
> +                                     dstx - dstw,
>                                       dsty,
>                                       dstx + dstw,
> -                                     dsty + dsth,
> +                                     dsty + dsth * 2,
>                                       vertices);
>
>          glamor_set_normalize_tcoords(src_pixmap_priv[0],
>                                       src_xscale[0],
>                                       src_yscale[0],
> -                                     srcx,
> +                                     srcx - srcw,
>                                       srcy,
>                                       srcx + srcw,
> -                                     srcy + srch,
> +                                     srcy + srch * 2,
>                                       texcoords);
>
> -        glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
> +        glScissor(dstx, dsty, dstw, dsth);
> +        glDrawArrays(GL_TRIANGLE_FAN, 0, 3);
>      }
> +    glDisable(GL_SCISSOR_TEST);
>
>      glDisableVertexAttribArray(GLAMOR_VERTEX_POS);
>      glDisableVertexAttribArray(GLAMOR_VERTEX_SOURCE);
> --
> 2.0.1
>
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