[Xorg] Re: X on OpenGL

Lars Knoll lars at trolltech.com
Wed Jul 14 01:07:56 PDT 2004

On Tuesday 13 July 2004 22:31, Jon Smirl wrote:
> --- Ian Romanick <idr at us.ibm.com> wrote:
> > This really *is* a tractable problem.  If our only worry is about
> > being able to use some API to access functionality of the hardware,
> > the only variable is how much code we want to write to do it.
> This is a map of the ATI X800 chip:
> http://graphics.tomshardware.com/graphic/20040504/images/architecture.gif
> Note how much of the chip is labeled 2D versus the rest which is
> implementing 3D. 2D is not getting any faster, but 3D is getting much
> faster each generation. X on OpenGL takes advantage of this hardware
> trend.
> Cairo has benchmarked 2D drawing on xlib vs glitz/OpenGl (using ATI
> proprietary drivers on radeon 9800) as OpenGL being 100 to 1 faster. In
> some tests it is 400 to 1. In five years 2D is going to be where VGA is
> today.

Actually we've done the same now for Qt 4 (having a possibility to issue the 
same 2d painting commands with regular X or on a open GL widget). The openGL 
code renders our example at least a factor of 50-100 faster on all X servers 
that have hardware openGL support.

Another reason I see is that there is lots of work going on to implement and 
imrpove open GL support for different hardware, while there is almost no work 
done on the 2d front. After more than 2 years with RENDER, there are still 
almost no X drivers that implement hardware acceleration for simple things as 
rendering a pixmap with an alpha channel. And since Xft, this is one of the 
more common operations the server has to perform.

Best regards,

> Also, don't get hung up on a 3D UI. We're not build a 3D UI, we using
> the 3D hardware to make a very fast 2D UI. At some point it may do some
> 3D UI things but that's not the initial goal. Speeding up drawing lets
> you do things that weren't possible before like translucency and
> complex animations.
> =====
> Jon Smirl
> jonsmirl at yahoo.com
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