四元数标准化

 static Quaternion NormalizeQuaternion(Quaternion rotation)
        {
            float magnitude = QuaternionMagnitude(rotation);

            if (magnitude > 0f)
                return ScaleQuaternion(rotation, 1f / magnitude);

            Debug.LogWarning("Cannot normalize a quaternion with zero magnitude.");
            return Quaternion.identity;
        }

        static float QuaternionMagnitude(Quaternion rotation)
        {
            return Mathf.Sqrt((Quaternion.Dot(rotation, rotation)));
        }

        static Quaternion ScaleQuaternion(Quaternion rotation, float multiplier)
        {
            rotation.w *= multiplier;
            rotation.x *= multiplier;
            rotation.y *= multiplier;
            rotation.z *= multiplier;
            return rotation;
        }