[Xorg] Re: X on OpenGL

Martijn Sipkema msipkema at sipkema-digital.com
Tue Jul 13 06:01:25 PDT 2004

Jon Smirl wrote:
> --- John Dennis <jdennis at redhat.com> wrote:
> > On Sat, 2004-07-10 at 23:45, Andy Sy wrote:
> > > I certainly would have to defer to the judgement of those who are
> > > more familiar with the API and the its implementation efficiency on
> > > different cards, but considering how ironic the fact that it is an
> > > API which was expressly developed to rely on an external 2D window
> > > manager and is now being used to implement one itself, I believe
> > > many would need more convincing as to its appropriateness.
> > 
> > OpenGL was partitioned to be independent of the windowing system
> > because OpenGL is a rendering system ONLY and because OpenGL 
> > needed to co-exist with existing windowing systems on various
> > platforms.
> > 
> > A windowing system includes as one its many roles the task of
> > rendering. Assigning the task of rendering for a windowing system
> > to a rendering API which is windowing system neutral is completely
> > consistent with the design goals of OpenGL.
> Think of X as a full screen app. This app then draws the windows using
> the OpenGL drawing API. All of the clipping, compositing, etc is
> handled in the X server.

I don't think this would be an ideal solution. You would not be able to
use hardware clipping or support a framebuffer with more than one pixel

> Another way to look at it is to think of XAA as an API which supports
> full screen drawing.  Then X is implemented on top of XAA. OpenGL will
> just replace XAA.

Would it not be nicer to have a library for setting up the framebuffer and
allocating windows and have OpenGL draw into these windows? That
would also allow applications to render directly into the framebuffer.


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