Function ray_vs_triangle 

pub fn ray_vs_triangle<T: Float>(
    r0: Vec3<T>,
    rv: Vec3<T>,
    t0: Vec3<T>,
    t1: Vec3<T>,
    t2: Vec3<T>,
) -> Option<Vec3<T>>

returns the intersection point of ray r0 and normalized direction rv with triangle t0-t1-t2