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

[Anuj Phogat]

On Fri, Jun 10, 2016 at 10:38 AM, Anuj Phogat <anuj.phogat at gmail.com> wrote:
> 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.
>
Returning overlap=true for shared edge cases is not causing any
rendering issues, it just makes the driver choose a slower path.
So, the patches don't need Cc to stable tag.

>> 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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