🚀 go-pugleaf

Good reply, Allen. I see your point on several issues now. Except for...

In article <o75njjk@fido.asd.sgi.com>, akin@sgi.com (Allen Akin) writes:
> [ ... ]
> 
> | An API running on a subset of PEX will emulate the missing
> | functionality in client-side software. This is the same thing OpenGL
> | does when running on machines which have little or no support in
> | hardware for its rendering features.
> 
> Yes, you've touched on a key point.  It deserves further clarification.
> 
> My first concern is for applications based on PEXlib.  PEXlib is often
> advertised as an efficient, "thin-veneer" API for PEX in the same sense
> Xlib is an API for the core X protocol.  

Well, I hear PEXlib more often advertised as an SPI -- systems
programmer interface, not intended for use by applications.
Applications which directly use PEXlib should know what they are
getting themselves into. Look at how few programmers today use Xlib,
most use any of the toolkits or other APIs currently available.

> [ ... ]
> 
> | > PEX has no support for image operations.
> | 
> | This is certainly an unfair comparison. Any PEX implementation is by
> | definition only available in an X environment, which provides a wide
> | variety of low-level 2D operations.
> 
> [ ... valid statement about 24bit visuals deleted for brevity ... ]
> 
> In the future, PEX implementations may use the services of the X
> Imaging Extension (XIE) to handle textures.  This seems feasible only
> if every implementation of PEX also ships with an implementation of
> XIE.  And of course this may not be practical in window systems other
> than X.

This is one reason why it is extremely dangerous to try to compare PEX
and OpenGL, and why I always go "oh no, not again" everytime I see
such an attempted comparison. X and PEX have never claimed to be the
be all and end all of imaging. It is beyond the scope of both, and
falls completely into the realm of XIE. Saying "PEX doesn't provide
support for imaging and OpenGL does" is like saying "the Jeep can go
offroad but the Corvette can't". A useful comparison, if you want to
drive offroad, but an apples and oranges comparison nonetheless.
-- 

   -paul	pmartz@dsd.es.com
		Evans & Sutherland