POV-Ray : Newsgroups : povray.general : 2D function to 3D tube : Re: 2D function to 3D tube Server Time
4 Feb 2023 01:02:53 EST (-0500)
  Re: 2D function to 3D tube  
From: Tor Olav Kristensen
Date: 27 Dec 2022 22:55:00
Message: <web.63abbd85560d6168d6142c8889db30a9@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> "Tor Olav Kristensen" <tor### [at] TOBEREMOVEDgmailcom> wrote:

> I'll post my own code here, and maybe you can spot why it's not working with
> just a simple Phi calculation.

I have had a thorough look at your code and modified it. You can find it here:

Newsgroup: povray.text.scene-files
Subject: Rewrite of tubecurves.pov (2D function to 3D tube)
Date: 2022-12-27 22:37:15
From: Tor Olav Kristensen

> > I can not understand why that should be necessary. - But it could be that
> > it's me that's missing something...
> I can only imagine I have some minor error somewhere that gets magnified
> later....

Sorry, but I have not found out exactly where your problem is.

> All I'm doing is storing the vertices of the tilted circle in a 2D array, and
> then moving along the curve and storing those circles.  Then I travel around the
> stored points in the circle array and make quads with 2 triangles.  Standard
> stuff.
> ...

Yes, that's a sensible way to do it.

> Looks great in the positive quadrant/octant and in the smooth parts of
> the negative. So it's odd that it's not working well at specific points, and my
> graph of the Phi values was so discontinuous.
> Bear in mind that I've only done this for the implicit functions, not 3d the
> parametrics.  But I should get this sorted out and see what the problem is
> before I go any further.
> Thanks as always for your clear mind, sharp eyes, and _lightning fast_ code
> generation!

Hehe, no problem.

I had previously done some work related to this topic; with parametric
functions in 3D, so I already had some code to start with.

If you're interested, you can have a look at the "Trefoil Knot Tube"
example here:


Sometimes GitHub fails to render PDF-files and Jupyter Notbook files (.ipynb).
If that happens, just wait a litte and then try again.

Tor Olav

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