#http://www.2dcurves.com/quartic/quarticp.html#pearshapedcurve

vertices = D1:100 D2:100

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

m = -1 - sin(u)
n = 0.5*(1 + sin(u))*cos(u)

x = n*cos(v)
z = n*sin(v)
y = array_max(m)-m