Quoting Hugh Fisher <[EMAIL PROTECTED]>:

> 
> On 05/05/2005 06:24:04 AM, Jack Carroll wrote:
> >     Here's one possible reason.
> >     Some video card applications, such as desktop publishing,
> > don't
> > require any acceleration whatsoever.  The simplest possible logical
> > interface that will let the X driver write to a high-resolution
> > framebuffer
> > is enough.  The image sharpness and color accuracy of the analog back
> > end
> > are the only things that market cares about.
> 
> Software-only rendering was discussed at a talk by Keith
> Packard, long time X guru, at LinuxConf 2005 a fortnight
> ago. He said it's just not workable anywhere outside the
> PDA market. Modern GUIs spend a lot of time shuffling
> pixmaps - windows, icons, etc - around, and without
> hardware acceleration this is viewed as unacceptably slow
> by the majority of desktop users. (As PDAs get bigger
> screens, they'll go the same way.)
> 

I would disagree with that statement. IMHO Software-only rendering will still be
inportant in the future.

I am not an expert, but with my limited understanding of graphics chips I
believe that with the new demands being placed of graphics by the eye candy
crowd that that any professional level card will  need a 2D engine
independant of the 3D/OpenGL pipeline. This is because a professional level card
will need to be able to run an openGl thread and the eye candy simultaneously in
the new graphics enviroments. Otherwise your  OpenGL app and your anti-aliased
xterm will become bogged down as the former and your X server fight
over control over the graphics pipeline. One way around this problem is that
when an opengl context starts then the X server will fall back to software
rendering. 

A consumer level card will probably not need such a facility as Joe Public will
 either be running desktop publishing or a full screen game, not both
simultaneously. 

I suspect that modern CPUs are fast enough for software rendering if double
buffering is used by the X server. I main home computer is a SGI 320 which has a
 unified memory design with the the graphics system intergrated with the main
memory system (so no bandwidth constraints or latency delays copying data to
video/frame buffer ram over AGP/PCI). The Linux graphics drivers only support
frame buffer (not even a hardware cursor). Yet a PIII 833 can make quite a
snappy experience for X. The software rendering only become apparent when you  
scroll a window or the text console scrolls a lot of information. If we had
hardware acceleration of the cursor and bitblt then anyone using it wouldn't
know the difference.

Then again I could be displaying total ignorance of the subject. I should post a
query to the Xorg mailing list and see whether someone can enlighten me (or a
flame war erupts).

My 2c worth. :).

Tim. 


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