#http://www.mathcurve.com/courbes3d/spiraleconic/pappus.shtml

vertices = 12000

t = from (-20*PI) to (20*PI)

r = 1
a = rand2(PI*0.2, PI*0.8)

x = r*sin(a)*t*cos(t)
z = r*sin(a)*t*sin(t)
y = r*cot(a)*t
