I  just replaced the #switch statement with a #if statement and changed a few
other things like how the rotation angle is defined. POV-Ray was complaining
about the commas at the end of the vrotate functions in the macros below this
message.
Brendan Ryan

"Jerome M. BERGER" wrote:

> Chris Colefax wrote:
> >
> > As Kevin pointed out, what you've divided is the rotation angle, so every
> > second point will be *rotated* half as much as it should be (still at the
> > same radius), rather than scaled.  Also, the switch you've used is not
> > necessary, as you can actually use a counter variable that increments in
> > steps other than 1, eg:
> >
> > #macro star_prism (Sides, StarFactor, Height1, Height2)
> >   #local RotAngle = 360/Sides;
> >   prism {linear_sweep linear_spline Height1, Height2, Sides+1, x,
> >     #local Count = 0.5; #while (Count < Sides)
> >       vrotate (x/StarFactor, y*RotAngle*Count),
> >     #local Count = Count + 0.5;
> >       vrotate (x, y*RotAngle*Count),
> >     #local Count = Count + 0.5; #end
> >     x}
> > #end
>         Actually, you could even use directly  the angle as a counter, which
> should be faster (no multiplication):
>
> #macro star_prism (Sides, StarFactor, Height1, Height2)
>   #local RotAngle = 180/Sides;
>   #local EndAngle = 360-RotAngle/2; // to avoid rounding problems
>   prism {
>     linear_sweep linear_spline Height1, Height2, Sides+1, x,
>     #local Angle = 0;
>     #while (Angle < EndAngle)
>       vrotate (<1/StarFactor, 0, 0>, <0, Angle, 0>),
>       #local Angle = Angle + RotAngle;
>       vrotate (x, <0, Angle, 0>),
>       #local Count = Angle + RotAngle;
>     #end
>     x
>   }
> #end
>
>                 Jerome
>
> --
> *******************************

> * they'll tell you what can't * mailto:ber### [at] inamecom
> * be done and why...          * http://www.enst.fr/~jberger
> * Then do it.                 *
> *******************************

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