POV-Ray : Newsgroups : povray.newusers : Something amiss in my Prism {} object : Re: Something amiss in my Prism {} object Server Time
20 Jun 2021 17:02:48 EDT (-0400)
  Re: Something amiss in my Prism {} object  
From: Bald Eagle
Date: 3 Nov 2018 14:10:01
Message: <web.5bdde4288c8ce108765e06870@news.povray.org>
William F Pokorny <ano### [at] anonymousorg> wrote:

> See a couple things.
>
> You have 289 points (0-288) but specify 288 in the line:
>
> 0, 0.1, _Spline


And that was it.   I was juggling quite a few things while I was rewriting all
of this, and array size vs array elements is something I often stumble upon,
know that I do, was trying to be vigilant about it --- and failed.

 #local _Tooth = prism {
  cubic_spline
  0, 0.1, _Spline+1

Simply adding 1 did the trick.   :)


> Second, I 'suspect' the last three points should likely be:
>
> [286] = 14, 14
> [287] = 14, -0
> [288] = 15, -0
>
> Believe it the case you only need match point_list 2 to point_list end-1
> to close the cubic prism. However, if you want to match the continuity
> about that closing point, the effective control points previous and
> after must match too. In other words, it's common to repeat the first
> three points as the last three points with the prism's cubic spline.
>
> Bill P.

I understand, not real sure that's the case yet, but I do see an artifact now
that it's functioning and I've gotten some other debugging out of the way.

Very many thanks as always - a dose of clear thinking helps keep me sane.


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