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Old 10-13-08, 09:06 PM   #3
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Join Date: Oct 2008
Posts: 17
Default Re: Bug in 177.80 with glCopyTexSubImage2D, glGetTexImage, glReadPixels

Originally Posted by AaronP View Post
Thanks for reporting this. I reproduced the depth portion of the problem and filed a bug. However, I'm not seeing the color values read incorrectly. Can you clarify exactly what you mean by "sometimes"?
Forget about the color values: the only way I can reproduce it right now is when I move part of the window a little bit off the screen. In this case, it makes perfect sense to have some "undefined" values because of the pixel ownership test.

Note that since I reported the bug, some xorg package has been updated on my debian (then I reinstalled the nvidia driver as usual because the xorg package erases the symlink on glx).
At the time I reported the bug I didn't pay attention if it was only happening in this little-bit-off-the-screen case, but there is a good chance it was the only case.

Originally Posted by AaronP View Post
Note that if the unified back buffer is enabled, your application cannot draw to pixels in the back buffer (or the depth buffer) that are covered by another window.
Thanks for the unified back buffer (UBB) note, I was aware of this pixel ownership issue. However, in the nvidia-bug-report.log I sent, I found:
(WW) NVIDIA(0): UBB is incompatible with the Composite extension.  Disabling
(WW) NVIDIA(0):     UBB.
So, I guess I'm not falling in this case anyway. In addition, when I run the test, its window pops up on the top.
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