[compiz] XGL and Xorg confusion

[Karthik Ramgopal]

Hi,
      As there has been some confusion over Xgl and Xorg here, I thought I'd
just post this. XGL acts as a client to the Xserver and acts as a server for
all programs connecting to itself. Instead of displaying its results on a
monitor, it interprets the display and calls the appropriate OpenGL APIs;
the OpenGL driver physically interacts with the screen, keyboard and mouse.
So you do need a XServer with driver support for OpenGL acceleration to use
Xgl with composite window managers via glitz and glitz-glx.

AIGLX on the other hand does not require a separate server like Xgl. AIGLX
uses indirect rendering. The commands are first sent to X which then
redirects them to the GPU via the drivers. To support AIGLX the driver needs
to support GLX_EXT_texture_from_pixmap as well as Composite in order to use
compositing window managers. AIGLX has been integrated into Xorg since Xorg
7.1.

ATI proprietary drivers upto 8.41.7 did not have AIGLX support and hence XGL
had to be used. From 8.42 AIGLX support has been added.

Hope this clears it up.

Regards,
Karthik Ramgopal
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.freedesktop.org/archives/compiz/attachments/20080312/26f9124e/attachment.html