Wasn't it rossy who wrote:
>Hallo
>
>it follows a cut out of the User Manual:
>f_helix1(x,y,z, P0, P1, P2, P3, P4, P5, P6)
>
>P0 : Number of helixes - e.g. 2 for a double helix
>P1 : Period - is related to the number of turns per unit length
>P2 : Minor radius (major radius > minor radius)
>P3 : Major radius
>P4 : Shape parameter. If this is greater than 1 then the tube becomes fatter
>in the y direction
>P5 : Cross section type
>P6 : Cross section rotation angle (degrees)
>What does "is related to the number of turns per unit length " exactly mean.
>

>a movie of a moving coil spring.

>coil spring but the same number of windings.
>hopefully someone is able to help me, its very urgent!!
>I want to use it for a presentation of my final career project

I was a bit vague when I wrote that bit of my Isosurface tutorial (that
then got incorporated into the 3.5 documentation).

Since then, I've come to the conclusion that it's the number of radians
through which each helix turns in a unit length. So, for example, this
helix turns through two complete turns between y=-1 and y=1. 
[2Pi = one revolution per unit length]

isosurface {
  function { f_helix1(x,y,z,1,2*pi,0.01,1,1,1,0) }
  max_gradient 3
  contained_by{box {-1,1}}
}


-- 
Mike Williams
Gentleman of Leisure

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