Xgl and direct rendering

[Michel Dänzer]

On Tue, 2006-02-28 at 19:23 +0100, Matthias Hopf wrote:
> On Feb 27, 06 15:18:34 -0500, Owen Taylor wrote:
> > It may be that the only interesting case is full-screen video, which
> > is the easiest case to design, since the compositing manager basically
> > just has to get out of the way.
> 
> It definitively isn't.

What isn't what? :)


> > This "get-out-of-the-way-I'm-going-fullscreen" protocol is also needed
> > for fullscreen 3D games with direct rendering.
> 
> This shouldn't be much of a problem, the composition manager should know
> when a single nontransparent window is shown fullscreen.

Sure, but a mechanism to have the fullscreen front buffer be scanned out
directly by the display hardware would still be nice.


> [...]
> > With Xegl it gets even harder ... you'd need a GL extension with similar
> > capabilities to Xvideo or something like that.
> 
> Talked with many vendors and programmes, and all agreed that using pixel
> shaders is the way to go. Eventually, native support for YUV textures
> might go away in the future as well.

Not sure how this relates to the discussion about (not) using the
overlay, but I'd like to add a couple of points to that discussion:

      * Hardware overlays seem to be losing scaling and/or colour
        conversion capabilities in newer hardware generations, so some
        kind of shaders will still need to be involved with them.
      * Video playback is not the only use for overlays.

I'm leaning towards not putting too much effort into using the overlay
for video playback in a composited environment based on these and other
points.


-- 
Earthling Michel Dänzer      |     Debian (powerpc), X and DRI developer
Libre software enthusiast    |   http://svcs.affero.net/rm.php?r=daenzer