POV-Ray : Newsgroups : povray.newusers : Smooth circular rotation using spline : Re: Smooth circular rotation using spline Server Time
3 Feb 2023 15:26:46 EST (-0500)
  Re: Smooth circular rotation using spline  
From: SecondCup
Date: 24 Oct 2016 22:35:01
Message: <web.580ec41d34f9ab4bf0b3ab370@news.povray.org>
clipka <ano### [at] anonymousorg> wrote:
> Am 25.10.2016 um 02:56 schrieb SecondCup:
>
> > I'm trying to make my camera rotate around an object in a perfectly smooth
> > circular manner. The reason I'm having
> > trouble is that I want the camera to be slow in some parts sections of the
> > rotation while fast in other parts. I'm no math whizz so I an using the spline
> > identifiers rather than some complicated trigonometry code. Cubic_spline seems
> > to work closest (smoothest) to what I want it to do.
> >
> > Ive used a total of 12 points per rotation so far and the camera still
> > appears to 'wobble' in
> > and out toward the centre object.
>
> That's absolutely inevitable if you're using splines, as they cannot
> exactly represent circular arcs (those types supported by POV-Ray at any
> rate; you'd need the things called Rational B-Splines).
>
> My recommendation would be not to use a 3D spline at all, but use a
> 1-dimensional spline to map time to angle, and use straightforward
> trigonometry (or `vrotate`, or even just a `rotate` transformation) to
> compute a position from the angle.

Thanks Clipka,

I'll have a crack at it. The tricky part will be mapping the angle to the time


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