Xgl and direct rendering

[Matthias Hopf]

On Mar 01, 06 17:51:29 +0100, Michel Dänzer wrote:
> > > Sure, but a mechanism to have the fullscreen front buffer be scanned out
> > > directly by the display hardware would still be nice.
> > 
> > Right... But that isn't easily possible, as a front buffer suddenly
> > might become transparent, or moved to the background, and then we would
> > have to switch to an off-screen buffer, which is not doable right now.
> 
> It could always be the same buffer. In that case, you'd just have to
> switch back to scanning out the root/compositor window buffer and
> compositing the desktop.

I currently don't see how this can be done with OpenGL.

> > >       * Video playback is not the only use for overlays.
> > What other uses do you see for overlays?
> 
> Think of the overlay as providing two surfaces that can be combined more
> or less arbitrarily, and the scanout location of each can be changed
> independently, and use your imagination. :) (Or alternatively, look at
> what the proprietary drivers use it for ;)

Well - I don't know :)

I know that OpenGL overlay in NVidia and ATI drivers is for legacy
applications (there are some *imensely* important legacy apps out
there).  The ATI driver doesn't even allow the simultaneous use of
XVideo and OpenGL overlays.

As I said, I don't know other important use cases for overlays - none
for which no better designed interface is already available.

Matthias

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