[metapost] Redefine ..

[Boguslaw Jackowski]

Hi,

HH> however, the next challenge is to catch a 'cycle'.
TH> Indeed Hans.  Any thoughts on tackling that?
[...]
HH> Probably best is to have a new symbol
[...]
HH> draw (1,1,9) .!. (2,1,6) .!. (3,2,5) .!. (4,1,5) .!. threeDcycle ;

Pretty neat. :)

Still, there remains a little bit more difficult challenge:
to allow tensions in path expressions. And then -- curly braces...

I believe that the redefining of the "horizontal colon" is
a road to nowhere. The MF/MP lingo is too weak. It does
not allow for introducing "private" structures.

First of all, tuples are limited to 2-tuple
(pair), 3-tuple (RGB color), 4-tuple (CMYK color), and 6-tuple
(transform), coordinates of each accessed differently.

You are not allowed to define your own tuple and indexed
variables cannot be used equivalently as components
of expressions. And paths are one level above tuples.

What one would actually need is to define a structure
corresponding to 3D path and project it into 2D space.
This is clearly impossible if one wants to preserve
the "syntactic sugar" of MF/MP.

All in all, I'd vote for Troy's inital attempt. i.e.,
the defining of a  3D --> 2D function and apply it to every node.

Good luck -- cheers -- Jacko

Cheers -- Jacko

-- 
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  Bogus\l{}aw Jackowski: B_Jackowski at GUST.ORG.PL
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  Hofstadter's Law: It always takes longer than you expect, even
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