用点乘和叉乘再加if嵌套即可完成

Vector3 a = Vector3.Cross(transform.forward, dog.transform.position - transform.position);
        float pos = Vector3.Dot(transform.forward, dog.transform.position - transform.position);

        if (a.y > 0)
        {
            if (pos >= 0)
            {
                print("在玩家右前方" + pos + "度数" + a.y);
                if (a.y < 30 && a.y > 0 && (int)pos <= 5f)
                {
                    print("发现入侵者");
                }

            }
            else
            {
                print("在玩家右后方" + pos + "度数" + a.y);
            }
        }
        else
        {
            if (pos >= 0)
            {
                print("在玩家左前方" + pos + "度数" + a.y);
                if (a.y < 20 && a.y > 0 && pos >= (-5f))
                {
                    print("发现入侵者");
                }
            }
            else
            {
                print("在玩家左后方" + pos + "度数" + a.y);
            }
        }