[Bug 43879] (xorg-server 1.11.2-2, xf86-video-ati 6.14.3-1 or git, qt 4.7.4) black pixels instead of transparency from PNGs

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=43879

Michel Dänzer <michel at daenzer.net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|xorg-driver-ati at lists.x.org |mesa-dev at lists.freedesktop.
                   |                            |org
          QAContact|xorg-team at lists.x.org       |
            Product|xorg                        |Mesa
          Component|Driver/Radeon               |Mesa core

--- Comment #2 from Michel Dänzer <michel at daenzer.net> 2011-12-16 07:24:36 PST ---
AFAICT from looking at it in apitrace, the game itself seems at least partly to
blame:

* It doesn't pass GLX_ALPHA_SIZE with a non-0 value to glXChooseFBConfig, so it
can't rely on the FBConfig having an alpha channel.
* It passes GLX_BIND_TO_TEXTURE_RGB_EXT (instead of
GLX_BIND_TO_TEXTURE_RGBA_EXT) to glXChooseFBConfig and passes
GLX_TEXTURE_FORMAT_RGB_EXT (instead of GLX_TEXTURE_FORMAT_RGBA_EXT) for
GLX_TEXTURE_FORMAT_EXT to glXCreatePixmap, so it can't rely on that the
FBConfig can be bound to a texture with an alpha channel.

That said, I tried overriding these values in gdb, but the problem was still
there, so there could be a Mesa issue as well. Anyway, it doesn't seem to
happen with LIBGL_ALWAYS_INDIRECT=1 but does happen with llvmpipe, so
reassigning to Mesa core for now.

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