[Mesa-dev] [PATCH] i965: setup address rounding enable bits

[Liu Aleaxander]

On Sat, Oct 15, 2011 at 2:11 AM, Eric Anholt <eric at anholt.net> wrote:
> On Thu, 13 Oct 2011 11:34:34 +0800, Yuanhan Liu <yuanhan.liu at linux.intel.com> wrote:
>> The patch(based on the reading of the emulator) came from while I was
>> trying to fix the oglc pbo texImage.1PBODefaults fail. This case
>> generates a texture with the width and height equal to window's width
>> and height respectively, then try to texture it on the whole window.
>> So, it's exactly one texel for one pixel.  And, the min filter and mag
>> filter are GL_LINEAR. It runs with swrast OK, as expected. But it failed
>> with i965 driver.
>>
>> Well, you can't tell the difference from the screen, as the error is
>> quite tiny. From my digging, it seems that there are some tiny error
>> happened while getting tex address. This will break the one texel for
>> one pixel rule in this case. Thus the linear result is taken, with tiny
>> error.
>>
>> This patch would fix several oglc pbo subcase fail on both ILK, SNB and
>> IVB.
>
> I would really like to see a piglit test for 1:1 linear-filtered
> texturing being precise, like apparently you found in oglconform.  It's
> important to compositor developers.

Will try to write one next week.

Thanks,
Yuanhan Liu