function cross(r:&Vec3, v1:&const Vec3, v2:&const Vec3){
	r.x = v1.y * v2.z - v1.z * v2.y;
	r.y = v1.x * v2.z - v1.z * v2.x;
	r.z = v1.x * v2.y - v1.y * v2.x;
}