vertices = D1:65 D2: 4

u = from 0 to (2*PI) D1
v = from -1 to 1 D2

k = from 0 to 64 D1

m = mod(k, 2)

r = 10.0 + m*2

a = 0.9

b = in_range(v, -a, a)

x = r*sin(u)*b
z = r*cos(u)*b

y = if(b, v, v/3)*3

