On 12/11/2014 4:22 AM, Le_Forgeron wrote:
> Le 11/12/2014 09:34, omniverse a écrit :
>> "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.
>>
>>
>>
>
> So, it is per radian rather than per turn ?
>


Radians per unit length, I think.

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