[metapost] Trying to figure out MPLib

Boguslaw Jackowski jacko at bop.com.pl
Mon Aug 6 13:24:13 CEST 2012


Shriramana Sharma:
> As I said above, basically I need the smooth curves Hobby algorithm.
> MPost is one of the better known implementations out there. But if it

Matthew Skala:
> The algorithm is described reasonably well in a few pages of the MetaFont
> book, and (I would hope) also in Hobby's original papers.  Why not
> implement it yourself?  I suspect that might be less work than trimming
> all the TeX dependencies off of MetaPost.

Bull's eye! -- "is described reasonably well". :)

I spent a few months trying to understand in details how it works,
assembling scattered pieces of the description (The MFbook,
J.D. Hobby's Thesis and the relevant publications, most
notably J.R. Manning's "Continuity conditions for spline
curves", and last but not least -- the MF.web source).

I prepared a careful note for myself -- alas, in mother tongue,
i.e., in Polish. :-/ I'm going to translate it into English,
but the time is always too short. There is a chance, however, that by
the end of this year I'll manage to be ready with the translation.
Thanks for providing the motivation.

Nevertheless, Marek Ry\'cko (who is a mathematician but knows
rather little about the intestines of MF/MP) was able within
a much shorter time spread than I spent on translating the
documentation to "MF-less math" was able to implement the
algorithm in Python. If somebody is interested in the code --
please contact Marek.

Cheers -- Jacko

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