--判断血条是否在屏幕中

public bool IsInView(Vector3 worldPos)     {         Transform camTransform = Camera.main.transform;         Vector2 viewPos = Camera.main.WorldToViewportPoint (worldPos);         Vector3 dir = (worldPos - camTransform.position).normalized;         float dot = Vector3.Dot (camTransform.forward, dir);//判断物体是否在相机前面          if (dot > 0 && viewPos.x >= 0 && viewPos.x <= 1 && viewPos.y >= 0 && viewPos.y <= 1)             return true;         else             return false;     }      void Update ()      {         Vector2 vec2 = Camera.main.WorldToScreenPoint (this.gameObject.transform.position);          if (IsInView (transform.position))          {             rectBloodPos.gameObject.SetActive (true);             rectBloodPos.anchoredPosition = new Vector2 (vec2.x - Screen.width / 2 + 0, vec2.y - Screen.height / 2 + 60);         }         else             rectBloodPos.gameObject.SetActive (false);     }

第二种:通过monoBehaviour来判断

void OnBecameVisible(){//可见状态下你要执行 的东西}void OnBecameInvisible(){//不可见状态下你要执行的东西}