[offtopic] Re: Proprosed break in libGL / DRI driver ABI

[Allen Akin]

On Thu, Apr 07, 2005 at 10:40:55AM -0400, Adam Jackson wrote:
| This would suggest to me one or more of the following:
| 
| - xprint should be investigating tiled rendering solutions, possibly based on
|   the glxproxy code from Xdmx
| - GL is an architecturally poor match for printing

In OpenGL the concept of a framebuffer is fundamental, so if you believe
a printing process can't afford a framebuffer, then OpenGL is definitely
a poor match for that process.

On the flip side, it seems to me that people want features for printing
that are part of the OpenGL rendering model and that are most easily
implemented with a framebuffer. :-)

Tiling involves some subtle tradeoffs.  The OpenGL spec requires that
the pixel fragments generated by rasterization be unaffected if
primitives are translated by an integral amount in screen coordinates,
or if scissoring is enabled.  Those two requirements are intended to
make it possible to tile rendering without generating visible seams at
the tile boundaries.  But the same requirements would have to be met by
a higher-level utility if you want to do tiling there, and it may not be
possible to meet them if the underlying OpenGL renderer doesn't offer
enough coordinate and color (etc.) precision to the higher-level
utility.

So at first glance, it appears to me that the only place to solve the
problem is in the OpenGL implementation.  I wouldn't expect it to be
easy, though.

Allen