动态加载切换Atlas资源

using UnityEngine;using System.Collections;public class Test : MonoBehaviour {    GameObject a;    public UIAtlas at;// Use this for initializationvoid Start () {        a = GameObject.Find("Invisible_Widget");        }// Update is called once per framevoid Update () {}    public void ButtonClick()    {             UISprite b = NGUITools.AddSprite(a, at, "Pinky");        b.MakePixelPerfect();    }    }