Re: Why run xserver on the OpenGL API?

Keith Packard wrote:
> Around 17 o'clock on Nov 25, John McCutchan wrote:
> 
> 
>>Why does an opengl extension need to be written to provide the frame
>>buffer access? what do you need that you can't accomplish already with
>>glReadPixels () and glDrawPixels ()?
> 
> 
> Yes, we can synthesize direct frame buffer access with these two functions
> for an unextended GL library, but performance will be dramatically impacted
> as I pull huge chunks of the buffer up into the X server, draw a few pixels
> and push them all right back again.
> 
> A simple direct frame buffer mapping and locking extension will allow us to
> run all of the existing dumb frame buffer code without change, dramatically
> speeding the migration to an OpenGL-based X server with no negative
> performance implications.  Along the way, we may be able to identify a few
> kinder looking GL extensions to reduce dependence on the frame buffer
> mapping extension -- there are a few X pixel operations not supported by GL
> that might make good candidates (plane masks, per-component alpha, conjoint/
> disjoint compositing operators).  
> 
> If you grant that it's interesting to move the X server to the OpenGL API, 
> please grant that it may be worth breaking some of the GL abstractions to 
> make the effort more likely to succeed.

Keith,

Just re-iterating that I don't have an objection to this as an intermediate 
step.  I don't see it as desirable in the long run, but to get things working 
in the short to medium-ish term, I don't see a problem with this.

It will always be a nasty hack, though...

Keith