Mike Horvath <mik### [at] gmailcom> wrote:
> On 11/28/2016 6:42 PM, Mike Horvath wrote:
> > Clipka gave me these formulas to generate a cylindrical isosurface.
> >
> > #declare fL = function(x,y,z) {y*100}
> > #declare fC = function(x,y,z) {sqrt(x*x+z*z)*128}
> > #declare fH = function(x,y,z) {atan2d(x,z)}
> >
> > What would be a formula for a sphere? L should be latitude, H longitude,
> > and C radius.
> >
> > Thanks.
>
> Would I use atan(x,y) for L? This produces values between -90..90
> degrees, correct? Or should it be atan(z,y)?

I sure don't know enough to tell you much of anything, the sphere equation is
something like:

function(x,y,z,r) {(pow(x,2)+pow(y,2)+pow(z,2))-pow(r,2)}

There's also the inbuilt function called internal (61) used by functions.inc for
its f_sphere(x,y,z,r) where r is radius. Hopefully I got this right, please
don't count on it!

Bob

P.S. I was trying, rather clumsily, to get the idea of what you might have been
trying to make and only succeeded in creating strange isosurface shapes. Some
were a partial sphere with both a vertical and horizontal cut across it,
thinking I changed to atan(y) and atan2(x,z) but I got lost in the fascination
of new shapes.

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