"Anthony D. Baye" <Sha### [at] spamnomorehotmailcom> wrote:
> f_helix1(x,y,z,n,p,r,R,s,c,a)
> supposedly, the fifth parameter is the period, or "Number of turns per unit
> length".
>
> The way I read this is that, for every unit the helix object rises, it should
> make one complete turn.  This is obviously not the case.

Anthony, I can confirm same here.

Slightly different wording found in the Insert menu, Special shapes|Isosurfaces
by function.inc and placing the Isosurface f_helix into a scene file, so I went
looking for the source code after realizing it was essentially saying the number
of turns is based on a complete circle. Meaning if you apply that 2*pi to your
number of turns you should get what you expected. I checked this and seemed to
work.

Source code makes very little sense to me, although a coding math wizard
probably could get the 2*pi introduced into there somehow.

You can look it over yourself at (line 519):

https://github.com/POV-Ray/povray/blob/3.7-stable/source/backend/vm/fnintern.cpp

Guessing it's the r or r2 variables which would require the 2*pi to complete
whole turns for the "period" parameter.

Looking at the online documentation, almost halfway down page at:

http://www.povray.org/documentation/view/3.7.0/448/

I see it also says "related" to number of turns, suggesting again it wasn't
actually made to do a user-specified amount.
Interesting thing, if not, because I would have thought same as you did.

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