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

[Anuj Phogat]

On Fri, Jun 10, 2016 at 7:43 AM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
>
> Is there a test or bug this fixes?  If so, that should be mentioned in the
> commit message and you should cc stable.
>
Looks like there is no test hitting this. So, I'll add a small piglit test
verifying the fix. I'll also put "Cc: 12.0 <mesa-stable at lists.freedesktop.org>"
tag on both the patches.

> On Dec 11, 2015 2:39 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.
>>      -----------
>>     |           |
>>      ------- ---
>>     |       |   |
>>     |       |   |
>>      ------- ---
>>
>> Cc: Ian Romanick <ian.d.romanick at intel.com>
>> Cc: Matt Turner <mattst88 at gmail.com>
>> Signed-off-by: Anuj Phogat <anuj.phogat at gmail.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
>>
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