[Mesa-dev] [Bug 96943] [gallium] glCopyPixels is affected by enabled texture state

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=96943

            Bug ID: 96943
           Summary: [gallium] glCopyPixels is affected by enabled texture
                    state
           Product: Mesa
           Version: git
          Hardware: Other
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Mesa core
          Assignee: mesa-dev at lists.freedesktop.org
          Reporter: imirkin at alum.mit.edu
        QA Contact: mesa-dev at lists.freedesktop.org

The recently rewritten copy-pixels test has exposed some failures in st/mesa.
When there's an overlapping copy (among other conditions), the operation
becomes a fb read + draw of that texture with the current fragment shader
modified in the same way as glDrawPixels does it. (So this problem might extend
itself to glDrawPixels as well).

Doing a glDisable(GL_TEXTURE_2D) before the glCopyPixels() call in the piglit
fixes the issue. Effectively that texture is being multiplied with the copied
data, whereas from what I can tell, it shouldn't be. I think the multiplication
comes from the ff-generated shader.

[An alternative is that the piglit test and i965 are wrong and what gallium is
doing is correct. I don't think that's the case, since the only disagreement is
on the overlapped copy.]

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