[Mesa-stable] [PATCH 1/2] mesa: Fix region overlap conditions for rectangles with a shared edge

[Anuj Phogat]

Returning overlap=true for shared edge cases is not causing any
rendering issues, it just makes the driver choose a slower path.
So, both these patches are not required on stable branches.

On Fri, Jun 10, 2016 at 12:54 PM, Anuj Phogat <anuj.phogat at gmail.com> wrote:
> From OpenGL 4.0 spec, section 4.3.2 "Copying Pixels":
> "The pixels corresponding to these buffers are copied from the source
>  rectangle bounded by the locations (srcX0, srcY 0) and (srcX1, srcY 1)
>  to the destination rectangle bounded by the locations (dstX0, dstY 0)
>  and (dstX1, dstY 1). The lower bounds of the rectangle are inclusive,
>  while the upper bounds are exclusive."
>
> So, the rectangles sharing just an edge shouldn't overlap.
>      -----------
>     |           |
>      ------- ---
>     |       |   |
>     |       |   |
>      ------- ---
>
>
> Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
> Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
> Reviewed-by: Nicolai Hähnle <nicolai.haehnle at amd.com>
>
> ---
>  src/mesa/main/blit.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/src/mesa/main/blit.c b/src/mesa/main/blit.c
> index a32f1a4..9c4c0f3 100644
> --- a/src/mesa/main/blit.c
> +++ b/src/mesa/main/blit.c
> @@ -68,16 +68,16 @@ _mesa_regions_overlap(int srcX0, int srcY0,
>                        int dstX0, int dstY0,
>                        int dstX1, int dstY1)
>  {
> -   if (MAX2(srcX0, srcX1) < MIN2(dstX0, dstX1))
> +   if (MAX2(srcX0, srcX1) <= MIN2(dstX0, dstX1))
>        return false; /* dst completely right of src */
>
> -   if (MAX2(dstX0, dstX1) < MIN2(srcX0, srcX1))
> +   if (MAX2(dstX0, dstX1) <= MIN2(srcX0, srcX1))
>        return false; /* dst completely left of src */
>
> -   if (MAX2(srcY0, srcY1) < MIN2(dstY0, dstY1))
> +   if (MAX2(srcY0, srcY1) <= MIN2(dstY0, dstY1))
>        return false; /* dst completely above src */
>
> -   if (MAX2(dstY0, dstY1) < MIN2(srcY0, srcY1))
> +   if (MAX2(dstY0, dstY1) <= MIN2(srcY0, srcY1))
>        return false; /* dst completely below src */
>
>     return true; /* some overlap */
> --
> 2.5.0