[PATCH 0/1] MR132: opengl32: Don't prioritize low bit depth formats with non-matching stencil.

[Matteo Bruni (@Mystral)]

On Mon Jun 20 16:08:35 2022 +0000, Paul Gofman wrote:
> I run the test on my AMD / Windows and added some traces / additional
> tests. I am attaching diff to the test (which includes your patch as
> well) and the output from AMD / Windows.
> It seems that unfortunately 32/8 tests is a bit inconclusive here as
> somehow the output pixel format is 32 / 8 (honestly not sure what that
> means but that's what I see here; see no test failure on line 382 and
> trace output from line 381).
> The rests of tests suggest that it prefers 24 bit whenever in doubt,
> see, e. g., 8x8 test, trace at line 364: it could choose 16x8 but
> preferred 24x8. From what I see it seems that the pattern is whenever
> stencil is requested it returns depths >= 24. That's what my current
> patch is doing. If we prioritize stencil formats when requested over
> depth match that will probably look more straightforward logic-wise but
> that would break all those tests if we'd tighten them to what is
> actually returned on AMD. Also, if specific games depending on the
> stencil choice are concerned, if we plainly prioritize stencil presence
> they will get 16 bit depth on Wine while getting 24 on Windows and that
> difference may matter (even if not break the thing completely like
> returning no stencil format).
> What do you think?
> [diff.txt](/uploads/4355976f66b6decb44d43c5b126e5479/diff.txt)
>  [output.txt](/uploads/13bfe7a03d34c1303f04612c9d809e0e/output.txt)
It seems pretty clear and reasonable to me actually. It looks like ChoosePixelFormat() returns a pixel format with stencil bits when requested so. Matching depth bits comes at a lower priority.

As it turns out, the only actual pixel format with stencil bits that's supported everywhere is D24S8. D32S8 is apparently supported on Windows AMD, but not on Windows Nvidia. FWIW Linux AMD doesn't return any D32 visual / fbconfig at all.

I'm attaching some more changes on top of yours: [choosepixelformat.txt](/uploads/b892cfcd3cb9fb13f8eee3ab81b2ddfb/choosepixelformat.txt). Basically I swapped the two blocks for stencil and depth in wglChoosePixelFormat(), making sure we take care of stencil before checking depth.

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https://gitlab.winehq.org/wine/wine/-/merge_requests/132#note_2409