So...

All I want to do is start out at <1,0,0> and spiral up to the top of a
hemisphere.  I want to be able to vary the vertical step up (via angle, of
course) and the horizontal step.  I can make plain old vertical columnar spirals
all day long, but I'm just not getting the translation for the hemisphere.  The
eqs I have found online aren't quite doing what I want - I get fancy loxo
things, but not just a nice spiral.

Here's what I'm using:

#declare Theta = 0;
#declare Phi = 0;

#while (Theta < 2*pi*10 )

      sphere { <0,0,0>, .05 texture { T_Stone3 } translate
<cos(Theta)*sin(Phi),abs(cos(Phi)),sin(Theta)*sin(Phi)> }

    #declare Theta = Theta + pi/120;
    #declare Phi = Phi + pi/12;

#end

If I leave the Phi out of it all, just using the X and Z, I get my nice columnar
spirals.  Nice if I want to make car springs, that is!  I am going to use this
to make indents on a golfball, but it is really just a concept struggle at this
point.  I just want a nice, adjustable, hemispherical spiral!  Argh!

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