[Xorg] X on OpenGL

[Ian Romanick]

Soeren Sandmann wrote:

> - vblank notification
> 
> OpenGL doesn't deal with this at all. Applications will want a Sync
> counter to block on. To do that the server needs to be notified when
> vblank starts. Ideally it would be possible to get notifications when
> the beam reaches a given scanline.

There are OpenGL extensions to support this functionality, and several 
of the open-source drivers support some of them.  See the following:

http://oss.sgi.com/projects/ogl-sample/registry/OML/glx_swap_method.txt
http://oss.sgi.com/projects/ogl-sample/registry/OML/glx_sync_control.txt
http://oss.sgi.com/projects/ogl-sample/registry/SGI/swap_control.txt
http://oss.sgi.com/projects/ogl-sample/registry/SGI/video_sync.txt

If they don't cover all the functionality that apps need, we can define 
our own extensions that do.