[metapost] Better gradient and 'special'

[laurent at math.toronto.edu]

Hi all,

In its version 3 of 1998, PostScript has provided
NATIVE support for many sorts of varying coloring.
This ranges from the simplest linear gradients, which
J.G. Andrade currently wants, to colorings suitable for
a smooth 3-D surface in slanting light ---
(aka shading, blending,...). See
http://www.adobe.com/devnet/postscript/pdfs/PLRM.pdf
Chap 4.5-4.10.

It seems that these features are not explicitly
supported by MP. Thus my question:-- is it feasible to
access these features using some sort of MP 'special'
command. Unfortunately, I read in the MP manual that
"The command

     special <string expression>

adds a line of text at the beginning of the next output
file."  Which suggests that the MP special command
still lacks the necessary power.  Is a more powerful
'special' planned?

Since MP is preprocessor to PostScript, a potentially
powerful 'special' mechanism (as for TeX) would seem
almost mandatory.

Comments please:)

Laurent Siebenmann