unity3d中检测一个物体是否在摄像机视野范围内

using UnityEngine;
using System.Collections;

public class CameraT3 : MonoBehaviour 
{
    // public
    public Transform targetTran;

    // private
    private Rect screenRect;
    private Camera camera;

    void Start ()
    {
        screenRect = new Rect(0, 0, Screen.width, Screen.height);
        camera = GetComponent<Camera>();
    }
    

    void Update ()
    {
        if (screenRect.Contains(camera.WorldToScreenPoint(targetTran.position)))
        {
            Debug.Log("进入摄像机范围！");
        }
        if (!screenRect.Contains(camera.WorldToScreenPoint(targetTran.position)))
        {
            Debug.Log("不在摄像机范围！");
        }
    }
}