#http://www.ipfw.edu/departments/coas/depts/math/coffman/steinersurface.html
#Steiner's Roman Surface. Three double lines, six pinch points, and a triple point.
#plot3d([r^2*sin(t)*cos(t), r*sin(t)*(1-r^2)^(1/2), r*cos(t)*(1-r^2)^(1/2)], r=0..1, t=0..2*Pi, numpoints=2500)

vertices = D1:160 D2:80
u = from 0 to (PI) D1
v = from 0 to (PI) D2

a = sin(u)
b = cos(u)

c = sin(v)
d = cos(v)

r = 5.0

x = r*r*b*d*c
y = r*r*a*d*c
z = r*r*b*a*d*d