[Xorg] XComposite, XDamage Extension with Xvideo or GL

Amir Bukhari ufz6 at rz.uni-karlsruhe.de
Sat Aug 7 10:59:17 PDT 2004

> On Gwe, 2004-08-06 at 18:45, Keith Packard wrote:
> > Around 19 o'clock on Aug 6, "Amir Bukhari" wrote:
> >
> > > Redirect OpenGL application to backing store pixmap does not work with
> > > Composite Extension (in Manual Mode) (Xserver always draw).
> >
> > Correct.  Fixing GLX to draw to off-screen memory will require
> additional
> > work.
> Not a huge amount on the GL side. Generally the GL applications in
> direct mode are already drawing off screen anyway and then blitting to
> the front display. A redirected OpenGL window would mean allocating
> another back buffer somewhere (probably on the X side since only X can
> deal with the "out of memory" failure sequence) and changing GL_FRONT to
> use it if neccessary.

What confuse me is the end (2D) image (after doing all 3D rendering) must be
draw to the OpenGL Window. This surely the job of X Server DDX Layer -
correct me if I am wrong -. As you said before most GL Application use off
screen to do their Direct Rendering, that mean at the end they should use a
way to copy the image to the OpenGL Window (like CopyArea). The hacks must
be in the phase of putting the end image on the OpenGL Window.

In my case, as I redirect a Window (which supposed to be OpenGL Window), the
X Server draw always the Image on its origin position.

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