[PATCH v2 1/4] d3d9/tests: Add Fetch4 tests

[Axel Davy]

On 28/01/2019 11:16, Stefan Dösinger wrote:
> On 27/01/2019 01:04, Axel Davy wrote:
>> Hi,
>>
>> Another info about the 0.5 offset is the following comments in the
>> r600 gallium driver:
>>                  /* Gather4 should follow the same rules as bilinear
>> filtering, but the hardware
>>                   * incorrectly forces nearest filtering if the texture
>> format is integer.
>>                   * The only effect it has on Gather4, which always
>> returns 4 texels for
>>                   * bilinear filtering, is that the final coordinates
>> are off by 0.5 of
>>                   * the texel size.
> This is interesting, and I guess it explains why I saw this behavior on
> r500 only when point mag filtering was enabled, but not when linear mag
> filters were set.
>
> Does that also apply for minification filters?
>
>
I'm not able to say, I guess you'd have to ask an AMD dev.
>> I experimented with 3DMark06, disabling support for D24X8 texturing to
>> force FETCH4.
> Do you know any application that uses fetch4 without having an
> alternative codepath, or insisting on using it on AMD cards even though
> an alternative codepath like PCF is supported by the application and
> used on Nvidia cards? For us, the reason to implement fetch4 is because
> DF24 implies it, and there are games like CS:GO that insist on using
> DF24 on AMD cards even though it happily uses INTZ on Nvidia cards.
>
Well I think it makes sense to use DF24 over INTZ if one doesn't need 
stencil.


As for the apps, apparently some old AMD demos are supposed to use it, 
but I haven't tested.


Axel