判断物体是否在镜头内

using UnityEngine;
using System.Collections;

public class _IsRendering : MonoBehaviour {

public bool isRendering=false;
private float lastTime=0;
private float curtTime=0;

void Update()
{
isRendering=curtTime!=lastTime?true:false;
lastTime=curtTime;
}

void OnWillRenderObject()
{
curtTime=Time.time;
}

}