[metapost] Re: pdf output and extensions

[Larry Siebenmann]

Taco wrote (Sun, 13 Mar 2005 11:01:01 +0100):

 > 4. allow these new features:
 >     <path> := envelope <path> withpen <pen>; % non-cyclic
 >     <path> := inner envelope <path> withpen <pen>; % cyclic
 >     <path> := outer envelope <path> withpen <pen>; % cyclic

Daniel H. Luecking  replied (Sun, 13 Mar 2005 14:38:30 -0600):

 >  Don't "inner" and "outer" already have a 
 >  contradictory meaning in MetaPost?
 >  ...
 >  "Be kind. Every person you meet is fighting a hard battle." - Anon.

Yes.

I suspect flaky thinking here, not just flaky terminology. For
example, what is this

  envelope <big Omega shaped path> withpen <medium sized circular pen>;

the path being embedded but the inked region having two boundary
components? This sort of thing will really occur.

At any rate "envelope" is a subject on which at least four mp and mf
activists, myself included, have done a good deal of work. You can
see traces of this on the "tex-fonts" list of a couple of years back.
To get a respectable mp solution (or solutions!) will require a lot
of patience consultation testing and possibly multiple publications
and programs.

The envelope problem might offer a good occasion to accomplish
something still more fundamantal to the health and prosperity of mp:

4*.  Implement protocols in mp for use of #external functions
and code modules#.

I am sure that would lead gracefully to solution of other hard
problems.

Cheers

Laurent S.

PS.  Recall that the "envelope" problem caused much pain in both mf
and PostScript. Related "envelope" problems in various dimensions
have occupied great mathematicians and physicists of the past,
including Huygens, Hamilton, Fresnel, Thom...


"Do unto others as you would have them do unto you." - Anon