用GUI实现倒计时：

方法一：利用Time.time,这是以秒计算到游戏开始的时间。也就是说，从游戏开始到到现在所用的时间。

代码如下：

using UnityEngine;using System.Collections;public class displayTime : MonoBehaviour{    //数值    public string myStringScore;    public float x = 85;    public float y = 19;    public float scale = 1;    public Color myColor;    //定义数组    public Texture[] myNumber = new Texture[10];    //public Texture Tex;    //    private int index = 0;    private int width = 30;    private int height = 30;    public float allTime = 100;    public float countTime;    void Start()    {        allTime = allTime + Time.time;    }    void FixedUpdate()    {        countTime = allTime - Time.time;        //print(countTime);        myStringScore = countTime.ToString();        if (countTime <= 0)        {            //游戏结束之后进行设置            countTime = 0;            //Application.LoadLevelAdditive(4);            //Application.Quit();//退出游戏            // print("countTime");            // return;        }        else        {            return;        }    }    void Update()    {    }    // Use this for initialization    void OnGUI()    {        GUI.color = myColor;        if (myStringScore != null)        {            for (int i = 0; i < myStringScore.Length; i++)            {                if (myStringScore.Substring(i, 1) == ".")                {                    break;                }                GUI.DrawTexture(new Rect(x + i * scale * width, y, scale * width, scale * height), myNumber[int.Parse(myStringScore.Substring(i, 1))], ScaleMode.StretchToFill, true, 0);                //GUI.DrawTexture(new Rect(x + i * scale * width, y, scale * width, scale * height),myNumber[myStringScore[i]-48]);            }        }    }}

绑定代码到Camera上，设置倒计时10个数图片：

 

 

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 方法二：使用yield return new WaitForSeconds(1);等待1秒

using UnityEngine;using System.Collections;public class CoolTime : MonoBehaviour {    // Use this for initialization    void Start () {    }    int CoolTimes = 100;    // Update is called once per frame    void Update () {    }    void OnGUI()    {        GUILayout.Label(CoolTimes.ToString());        if (GUILayout.Button("Begin"))        {            StartCoroutine(waitForOneSecond());        }    }    public IEnumerator waitForOneSecond()    {        while (CoolTimes >= 0)        {            CoolTimes--;            yield return new WaitForSeconds(1);           }    }}