三維向量夾角
Vector3 relative = transform.InverseTransformPoint(target.position);
float angle = Mathf.Atan2(relative.x, relative.z) * Mathf.Rad2Deg;
transform.Rotate(0, angle, 0);
二維向量夾角 (v1和v2為兩個向量)
Vector3 cross = Vector3.Cross(v1, v2);
float angle = Vector2.Angle(v1, v2);
angle = cross.z > 0 ? -angle : angle; //unity左手定則,求出夾角
