[Devel] ftstroker

[Graham Asher]

David,

I had a quick look at ftstroker and was very interested - it is directly
related to some of my work. From a 5-minute glance at the source I guess
that it supports only a circular pen at the moment. Will it (or does it
already, if I've been too hasty) one day support arbitrarily rotated
elliptical pens, as does METAFONT? METAFONT avoids solving the problem
analytically by cunning approximation using a polygonal pen that produces
the correct digitised result. Richard J Kinch has solved the problem
analytically in his MetaFog program. His paper "MetaFog: Converting METAFONT
Shapes to Contours" explains this in some detail (though not all details are
given, and the source of MetaFog is not available) and points out that
stroking a 3rd-degree (cubic) polynomial curve (the pen, if represented this
way) along a 3rd-degree curve (the stroke) produces a 6th-degree envelope
curve; Kinch approximates this closely using 3rd-degree curves.

Slanted elliptical pens give us calligraphic fonts; very nice for East Asian
scripts.

Best regards,

Graham