[Mesa-dev] [Bug 100668] No pixel formats with WGL_SWAP_UNDEFINED_ARB && WGL_DOUBLE_BUFFER_ARB=true

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=100668

--- Comment #2 from Brian Paul <brianp at vmware.com> ---
Hi Charles,

I compiled your test program and ran it with Mesa in a Windows VM and
wglChoosePixelFormatARB failed to find a pixel format.  But I found the exact
same failure when I ran it with NVIDIA's OpenGL driver on a Windows 7 system.

I also used the wglinfo utility to examine the double buffered pixel formats
offered with NVIDIA's driver.  None of them use WGL_SWAP_UNDEFINED_ARB. 
They're all tagged with either WGL_SWAP_EXCHANGE_ARB or WGL_SWAP_COPY_ARB.

I would expect that ANGLE is tested with NVIDIA's OpenGL driver, but I don't
know how things could work with the ANGLE code I see.

When you specify WGL_SWAP_METHOD_ARB = WGL_SWAP_UNDEFINED_ARB you're asking for
a very specific type of implementation of wglSwapBuffers().  Any given Windows
OpenGL driver is free to implement any of the three swap methods.  AFAIK, none
are required.  Note that WGL_SWAP_UNDEFINED_ARB doesn't mean "don't care".

Does ANGLE really require this specific type of buffer swap behavior?  If not,
the WGL_SWAP_METHOD_ARB attribute should simply be omitted.

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