PostScript patterns and colours

[Jeff Kingston]

I've had a request to add patterns (textures) to Lout, which I'm in the
middle of doing.

PostScript has a funny property: if you change the colour it forgets
the pattern.  (Please don't explain to me why this happens, I know
all about the /Pattern color space and the rest of it.)  This is funny
because logically, pattern and colour should be independent except that
coloured patterns override the current colour while they are in effect.

Has anyone else given thought to this peculiarity of PostScript?  If so,
I would like to hear your thoughts.  My current plan is to write my
own versions of the colour and pattern setting commands, ensuring that
changing the colour does not change the pattern, and changing the pattern
does not change the colour.  I've worked out how to do this.

Comments and suggestions welcome.

Jeff Kingston