POV-Ray : Newsgroups : povray.pov4.discussion.general : NURBS-Surface code in PovRay already exist : Re: NURBS-Surface code in PovRay already exist Server Time
2 Dec 2023 13:21:06 EST (-0500)
  Re: NURBS-Surface code in PovRay already exist  
From: Tor Olav Kristensen
Date: 4 Jan 2010 16:00:00
Message: <web.4b4255b6d18bdb3cd6291f840@news.povray.org>
"Tor Olav Kristensen" <tor### [at] TOBEREMOVEDgmailcom> wrote:
> "H. Karsten" <h-karsten()web.de> wrote:
> > Hi people,
> >
> > in this post: web.4afb068fe011e9f5da6353d60@news.povray.org I'd suggest to
> > support NURBS-surfaces is PovRay.
> >
> > Now I figured out that in MegaPov 0.6 support of NURBS already exist, including
> > trimming!
> No, I'm afraid that you are wrong Holger.
> Bezier curves and rational Bezier curves are both subsets of NURBS curves.
> The Bezier code in MegaPOV 0.6a (bezier2.c) seems to implement the de Casteljau
> algorithm, which is not very usable for creating B-splines.
> To create B-splines (and thereafter NURBS) one would typically use the Cox de
> Boor algorithm.

Sorry, I looked into the wrong c-file.

The right one seems to be rbezier.c. But also this file seems to be using the de
Casteljau algorithm, not the Cox de Boor algorithm.

Tor Olav

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