XComposite and GLX

Ralph Thomas ralpht at gmail.com
Sat Sep 25 23:24:02 PDT 2004

I don't know if this is helpful or not (as I don't know GLX server
internals), but couldn't you get GL programs to render off-screen by
creating a pbuffer with the same fbconfig as the visual of the
on-screen window, and then make the context current with the pbuffer
instead of the window?

If you can get something that looks like an XPixmap (representing your
off-screen window) located in video card memory, then you might be
able to create something like a GLXPixmap for it. This would allow you
to do mixed mode X/GL rendering.


On Thu, 23 Sep 2004 18:43:47 +0200, Amir Bukhari
<ufz6 at rz.uni-karlsruhe.de> wrote:
> now it is two days as I began study GLX, GLcore. to see how to redirect
> "indirect Software rendering" at the end I find the following:
> when GLX bind a window with context it assign the frontbuffer to the
> window. this window will be rendered to it. As we redirect this window
> with Composite its pixmap (normaly Screen pixmap) is replaced with
> offscreen pixmap. thus GLcore when rendered to window it use this
> offscreen and not directly access the framebuffer of the card.
> I could redirect glxgears to offscreen and also a simple example of GLX.
> my simple exmaple is redirect without problem. glxgears has some
> problem, I don't know, because I have redirected during it was mapped!
> when redirecting glxgears first the frame of the window manager go a way
> and secondly the the window of the main (glxgears) is moved to the top
> left corner and it always white until I kill it or kill my simple
> composite manager.
> if the above problem is not releated to Composite I think. Redirection
> of Server Side GLX rendering is already supported.
> On Tue, 2004-09-21 at 15:54, Amir Bukhari wrote:
> > I have began to study the GLX code, to see the best way of getting
> > Composite extension to support redirection of GLX. I will concentrate at
> > first on server side code (software rendering). this will be a key to go
> > afterwards to support DRI.
> >
> > I would like to know if there is someone has began this before or plan
> > to work in it, so that we could share ideas!
> >
> > please use this thread to discuss this issue.
> _______________________________________________
> xorg mailing list
> xorg at freedesktop.org
> http://freedesktop.org/mailman/listinfo/xorg

More information about the xorg mailing list