[eq-dev] wglWindow broken / FBO's and DC's on WGL

[Mathias Heyer]

Without an affinity-DC, you can't create a window-less FBO. But you can
create an invisible window (using a memory-undemanding pixel format), create
a render context for it and then use that RC to create a FBO which you will
then render into.

OpenGL3.0 will allow you to natively create a render context without
associated window.

Affinity DCs allow you to create a window-less render context, too.
This is what the specs say:

"     An affinity-DC has no window associated with it, and therefore it
      has no default window-system-provided framebuffer. (Note: This is
      terminology borrowed from EXT_framebuffer_object). A context made
      current to an affinity-DC will only be able to render into an
      application-created framebuffer object, or a pBuffer. The default
      window-system-framebuffer object, when bound, will be incomplete.
      The EXT_framebuffer_object specification defines what 'incomplete'
      means exactly. "

http://www.opengl.org/registry/specs/NV/gpu_affinity.txt


greetings,

Mathias


> -----Original Message-----
> From: eq-dev-bounces at equalizergraphics.com [mailto:eq-dev-
> bounces at equalizergraphics.com] On Behalf Of Stefan Eilemann
> Sent: Wednesday, January 14, 2009 10:08 AM
> To: Equalizer Developer List
> Subject: [eq-dev] wglWindow broken / FBO's and DC's on WGL
> 
> Hi all,
> 
> first and foremost this is a heads-up that the WGL code is currently
> broken. Please use revision 2454 for now.
> 
> Secondly this is a call for help: If anybody of you has working code
> which shows how to use FBO's on WGL without having a window or
> PBuffer, I'ld like to see it. As an added bonus, this code would work
> with and without affinity DC's.
> 
> 
> Cheers,
> 
> Stefan.
> 
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