Re: smooth shading & terminal specialities

[Ethan M. <merritt@u.washington.edu>]

On Monday 08 May 2006 12:26 pm, Daniel J Sebald wrote:
> 
> My opinion is that this "gppsfile" variable should be eliminated.  
> From what I understand, the purpose of this is a flag in the main 
> code that indicates a PostScript comment can be added to the file 
> for later use.  

Your understanding is wrong.  No post-processing is involved.
The gppsfile is the PostScript output stream itself.
If the current terminal driver is "post", this is only output
stream (gppsfile == gpoutfile).  But for epslatex, pslatex, etc,
it is a secondary output stream parallel to the TeX output.

> PostScript is the most feature rich language I'm aware of.  
> (The Adobe language reference should be consulted first.) 

It's beginning to show its age.  Poor support for UTF8 for
one thing, but more to the point in the present discussion --
it doesn't support gradient fill.  That puts it behind 
several of the other output drivers.

> I guess I've never completely understood the convention of 
> "default routine" in the terminal driver concept.  
> Someone will have to explain this.

Easy.  Some output devices have special requirements, or
special capabilities. So the corresponding terminal driver
needs a private routine to implement these requirements
or features.  But it would be silly to write a private
routine for every single driver, because most of them can
share a generic default routine.

For instance, some of the TeX variants support a "draw arrow"
command as a native operation, and can produce snazzier arrows
than gnuplot's generic do_arrow() routine.


-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle WA