Xgl and direct rendering

[Adam Jackson]

On Tuesday 14 February 2006 16:13, Michael Biebl wrote:
> Adam Jackson wrote:
>
> [..]
>
> > Xgl has no direct rendering support (which is to say, clients connecting
> > to Xgl will not get direct rendering).  Your problem assuredly lies
> > elsewhere.
>
> Judging from Dave's nice little demo where Quake3 runs at decent speed,
> some sort of direct rendering seems to be in use there. Does this maybe
> depend on the used hardware and driver?

In that demo, while Xgl is a direct-rendering client of the backend X server, 
q3 is an indirect-rendering client of Xgl.

The concepts of accelerated and direct rendering are orthogonal.  Direct 
rendering is always accelerated (well, excluding software fallbacks).  
Indirect rendering isn't always.  Xgl, and the aiglx branch of Xorg, 
accelerate indirect rendering; stock Xorg doesn't.

In particular Xgl accelerates indirect rendering iff the backend's GL 
implementation supports the GL_EXT_framebuffer_object extension; currently 
only nvidia's closed driver does, support in DRI should happen soonish.  The 
aiglx branch of Xorg accelerates indirect rendering pretty much all the time, 
but doesn't integrate with Composite correctly yet - again, coming soon.

- ajax
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