按角度偏移摄像机

float y = -Input.GetAxis("Horizontal");
        float speed;
        //加速
        if (Input.GetKey("left shift"))
            speed = 20 * 2;
        else
            speed = 20;
        //移动
        Vector3 r = new Vector3(0, 180, -8.35f);
        r.x = 0;
        //移动方式
        tr.position += Quaternion.Euler(r) * Vector3.left * y * Time.deltaTime * speed;