[Xorg] Re: X on OpenGL

Ian Romanick idr at us.ibm.com
Tue Jul 13 10:00:34 PDT 2004

Rich Wareham wrote:

> About the only problem I can foresee is that standard OpenGL only
> supports 2**n x 2**n textures although that can be overcome by some
> cunningness (maintain a set of textures and 'stitch' windows together
> from parts of them).

Almost all cards support {NV,EXT,ARB}_texture_rectangle and all next 
generation cards should support ARB_texture_non_power_of_two.  Two years 
ago this would have been a big issue, but it's pretty minor today 
(thankfully!).  In the open-source drivers, about half the cards are 
missing support, but I think about half of those (such as i810, Savaga, 
and Unichrome) could do it.

> Of course none of this negates the fact that there are a set of older
> cards which have only 2d acceleration. I guess the question is if people
> want to force users of these to accept software rendered OpenGL or
> whether a sufficient subset of OpenGL can be specified that can be
> implemented on 2D only hardware.

This will be a stinking point, I think.  Part of the problem is that 
over the past few years the hardware drivers have seen quite a bit of 
clever optimization, but software rendering has not.  It's a problem 
that could be solved with more man-power.  I'm not sure if all the 
optimization in the world would make it run good on a Pentium 200 and a 
ET4000. ;)

The flip side is, of course, that there are even a few 3D capable cards 
that don't have 3D support.  i740, Permedia2 (and most other 3dlabs 
chips), Rendition chips, Trident Cyberblade, and NV3 come to mind. 
There may be a few others.  Unfortunately, this isn't a purely man-power 
solvable problem.  We need docs. :(

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