POV-Ray : Newsgroups : povray.object-collection : SphereSweep 1.1, with B-splines : Re: SphereSweep 1.1, with B-splines Server Time 5 Dec 2021 00:49:23 EST (-0500)
 Re: SphereSweep 1.1, with B-splines
 From: Cousin Ricky Date: 7 Sep 2015 19:31:18 Message: <55ee1e46\$1@news.povray.org>
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On 09/05/2015 10:35 AM, And wrote:
> Well, I wondering what the radius formula do others like you apply? I think that
> it can be the similar form as the bezier curve in a sense:
>
> r = r0*pow(1-t,3) + r1*pow(1-t,2)*t + r2*(1-t)*pow(t,2) + r3*pow(t,3)
> 0 <= t <= 1
> That is, four points and four radii decide a segment.
> Wondering how do you think?

I am treating the radii simply as a 4th vector component, just as with
all the other spline types.  This seems consistent with how POV-Ray
determines the radii of B-spline and cubic sphere_sweeps.

SphereSweep 1.2 is in testing phase right now.  I had to create a test

segments made them trickier to implement than the other spline types.  I
am still working on the test cases for variable radius sweeps.

As it turns out, I did not need your code, so there is no concern about
licensing.
```