func (v Vec3) Len() float32 {
	return math32.Sqrt(v[0]*v[0] + v[1]*v[1] + v[2]*v[2])
}
func (v Vec3) Len() float32 {
	return math32.Sqrt(v[0]*v[0] + v[1]*v[1] + v[2]*v[2])
}
// Len derives the scalar scalar length of the vector. (len)