[Xorg] X on OpenGL

Adam Jackson ajax at nwnk.net
Fri Jul 9 16:38:27 PDT 2004

Hash: SHA1

On Friday 09 July 2004 19:25, Andy Sy wrote:
> In Keith's papers, he mentions having X use OpenGL 'for all graphics
> operations'.  Would something like the following layering work?
> DRM ---> DRI (or KGI) ---> some sort of non-windowed/fullscreen
> implementation of OpenGL  --->  X

That is, in fact, the plan.

> Is OpenGL really an appropriate API to build a windowing system on
> top of?  If it lacks certain calls to make such less kludgy, would
> these (for sure, these would be 2d operations) be appropriately proposed
> as OpenGL extensions or is everything elegantly expressible as a
> special case of 3d?

Anything it lacks can certainly be added, but I don't believe we've found any 
cases like that yet.  In particular, rectangles are just two adjacent 
triangles with all Z coordinates equal.

> The one big problem I see with the OpenGL API is that it does not give
> you any direct pixel-level access to the frame buffer and wouldn't it
> be extremely kludgy to build a windowing system without such?

man glReadPixels.

- - ajax
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