[Mesa-dev] Fwd: [Mesa-users] Issues with removal of classic OSMesa

Andreas Fänger a.faenger at e-sign.com
Tue Feb 9 13:27:20 UTC 2021

>> > I've fixed all the issues in that area, and I believe llvmpipe and
>> > softpipe mostly produce the same or very similiar results.
>> >
>> > I'm not overly impressed though by the texture quality at least the
>> > furmark trace shows as very blurry.
>> >
>> > Also the Vulkan CTS expects linear aniso to operate differently to how
>> > this has done it.
>> >
>> > Andreas, can you comment on this trace?
>> > https://tracie.freedesktop.org/dashboard/imagediff/mesa/mesa/7150044/gputest/furmark.trace/
>> >
>> > I'm pretty sure softpipe looks the same locally for the same trace,
>> > and it just seems overly blurry.
>> 1) Is it blurry in all cases you have tried or are there test cases
>> where it is better?
> I've only noticed it with furmark, but I don't have a lot of test
> cases, the GL CTS passes, the Vulkan CTS does look blurry and fails
> but it's unlikely that is due to the blur.
>> 2) Are the results better compared to linear?
> I'm not sure, better is pretty subjective measure here,
>> 3) Is the reference image produced with another anisotropy
>> implementation or with linear?
> The reference image is produced with whatever llvmpipe path was taken
> before this, which I assume is linear.
>> If 2) is not what you expect, then maybe the softpipe version is not
>> correct (anymore).
>> In general, I remember that results are a bit more blurry (compared to
>> linear) in the non-anisotropy case, ie. when textures are displayed
>> undistorted at 100%. But this doesn't seem to be the case in the trace
>> image here.
> I'd be interested in any test data you have or any output, afaics the
> llvmpipe output pretty much matches the softpipe output and if the
> softpipe output is currently acceptable then we should merge the MR to
> equalise them, and then fix any subsequent things on top in parallel.
> I'd like to solve the VK CTS issue which does a linear vs anisotropic
> compare and expects only a moderate amount of difference and we seem
> to exceed the difference threshold.

I've created and attached a simple test case. Note that this is a java 
application using the fixed function pipeline and is based on bindings 
to osmesa/classic swrast, as we are not using softpipe at all. But it is 
very simple and should not require much work to adapt it to another 
language/environment (hopefully).

Just change maxAnisotropy to either 16 or 1 to switch between using 
anisotropic filtering or not.

The texture has been taken from the wikipedia page 

The following images show results for both settings:

image with anisotropic filtering (16)

image without anisotropic filtering

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