1，摄像机射线：

 Ray ray = Camera.main.ViewportPointToRay(new Vector3(0.5f, 0.5f, 0));
        RaycastHit hit;
        if (Physics.Raycast(ray, out hit))
        {
            Debug.DrawLine(ray.origin, hit.point);  //显示出射线
            //Debug.DrawLine(transform.position, hit.point, Color.red);
            if (hit.collider.gameObject.name == "dogpoint") 
            {
                play.dog1();  
                hit.collider.gameObject.SetActive(false); //碰到的物体关闭
             }
         }

2， 物体发射射线：

//通过标签指定
//ray = new Ray(GameObject.FindGameObjectWithTag("Player").transform.position, GameObject.FindGameObjectWithTag("Player").transform.forward);
//通过cam 坐标
//ray = new Ray(game.position, game.forward);

 Vector3 fwd = transform.TransformDirection(Vector3.forward);
        RaycastHit hit;
        if (Physics.Raycast(transform.position,fwd,out hit))
        {
            Debug.DrawLine(ray.origin, hit.point);  //显示出射线
           //Debug.DrawLine(transform.position, hit.point, Color.red);
            if (hit.collider.gameObject.name == "dogpoint") 
            {
                play.dog1();  
                hit.collider.gameObject.SetActive(false); //碰到的物体关闭
             }
         }

3， 点击发出射线：

if (Input.GetMouseButtonDown(0))
        {    //首先判断是否点击了鼠标左键

            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);    //定义一条射线，这条射线从摄像机屏幕射向鼠标所在位置
            RaycastHit hit;    //声明一个碰撞的点(暂且理解为碰撞的交点)
            if (Physics.Raycast(ray, out hit))    //如果真的发生了碰撞，ray这条射线在hit点与别的物体碰撞了
            {
                if (hit.collider.gameObject.name == "Qingting")    //如果碰撞的点所在的物体的名字是“StartButton”(collider就是检测碰撞所需的碰撞器)
                {
                    print("蜻蜓");
                    play = ZT.s1;
                    }
                }
            }
        }