POV-Ray : Newsgroups : povray.advanced-users : Bezier spline deformation : Re: Bezier spline deformation Server Time
3 Jun 2023 10:06:32 EDT (-0400)
  Re: Bezier spline deformation  
From: Bald Eagle
Date: 21 Mar 2023 21:55:00
Message: <web.641a5fee122e7e3a1f9dae3025979125@news.povray.org>
yesbird <sya### [at] gmailcom> wrote:
> On 21/03/2023 23:21, Leroy wrote:
> > Do you have access to the C4D and POV source code ?
> > I know it's complicated but you might get an idea of where they differ.
> Thanks for suggestion, yes, I have POV sources, but can only dream about
> sources of C4D :)
> And even I will find the reason of difference (position of control
> points) in sources, I will not be able to control them in POV's 'prism':
> https://wiki.povray.org/content/Reference:Prism
> So the problem still exists ...
> --
> YB

So, years ago, when I still didn't have any real clue what was going on with
Bezier splines and patches, I thought that maybe different softwares might have
different equations for computing the cubic Bezier spline.

I don't see how that's that case, as Bezier curves all seem to be calculated the
same way, with the same, meaningful, purposeful equations, derived from the same
principles and adhering to the same behaviour and exhibiting the same properties
- such as partition of unity.  I'm not seeing how that could be done multiple
ways - without messing up things like True Type fonts, and the myriad other
applications of Bezier curves across different software packages and operating

So I am presuming that C4D uses the same equations that POV-Ray uses, which I've
at some point read the source code for, and matches the equations that I write
to make them myself.

The control points should transfer seamlessly, since they are just numerical
coordinates.  Although with a cubic, you need those "extra" control points which
don't show up but that affect the shape of the curve - so maybe that's where the
problem lies?

- BW

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