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List:       xfree-render
Subject:    RE: [Render] Question about DGA
From:       Mark Vojkovich <MVojkovich () nvidia ! com>
Date:       2002-07-04 3:03:42
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On Thu, 4 Jul 2002, Lawrence Lee (Shanghai) wrote:

> Thanks
> Yes, if the client can render in the frame buffer directly it will improve
> the speed greatly. But why DGA provides other methods like SET MODE? I think
> there may be two reasons:
> 1.   The client can't SET MODE through X lib
> 2.   The speed using DGA is faster than througn X lib(if it has).
> Which is right? and maybe other answers?

   DGA is not a windowed mode.  It is a fullscreen-only mode.  During
that time the X-server is essentially switched away to another VT.
For the most part, it is unrelated to what one would think of as
normal X-Window operation.  It was written so people could do DOS-like
games using page flipping.  It's built on top of XFree86 because XFree86
has drivers for alot of hardware.  Before DGA, people were using svgalib
from the console and they had trouble getting hardware supported as video
cards began to diverge from simple vga functionality.  In my opinion, the
time for DOS-like interfaces has passed and DGA should disappear.  People
should be using OpenGL instead. 

   If you want to see an app that showed what DGA was supposed to
do see http://www.xfree86.org/~mvojkovi/texture.tar.gz

   In my opinion, DGA has been deprecated and should not be used.


			Mark.
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