Function torus_surface 

pub fn torus_surface(major_r: f32, minor_r: f32, u: f32, v: f32) -> Vec3

Parametric surface of a torus embedded in 3D. major_r = distance from center of tube to center of torus minor_r = radius of the tube u = angle around the torus (0..2PI) v = angle around the tube (0..2PI)