Hello,

I'm by far no specialist for spline, but I hope that I can help you
anyway. So, I ask the others to correct me where I'm wrong.

Bret Slivka <coo### [at] chispnet> writes:
>
> Is there away to convert a bicubic, or bezier spline as used in
> illustrator to a cubic spline as used in povray,

As far as I know, the term "bicubic" is used for patches. In each of
the two directions ("bi-") you have a "-cubic" curve.

Bezier splines consist of piecewise cubic curves. They are described 
and connected in a particular way. According to the POV-Ray documentation,
you can use them for lathe and prism.

> I've noticed the behavior of a cubic spline and noticed that it's 
> difficult to make sharp corners.. 

The purpose of splines is to make smooth curves. That's why it is not
surprising that you have difficulties to make sharp corners. I suggest
that you use CSG for doing so. An intersection should do the trick.
If you don't know anything about CSG, read the sections in the POV-Ray 
documentation and/or ask for help in povray.newusers.

As reference for splines I have only a book, which contains probably
much more information than you want:

Su Bu-Qing and Liu Ding-Yuan
Computational Geometry Curve and Surface Modeling
Academic Press 1989
ISBN 0-12-675610-4

Thomas

-- 
http://thomas.willhalm.de/ (includes pgp key)

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