碰撞后如何启动计时器

Question

我想在游戏中创建一个奖励对象。当玩家拿起它时，计时器应该启动。

public void OnCollisionEnter2D(Collision2D col) //player collide with bonus
{
if (col.gameObject.name == "Cube")
{
StartTimer();
}
}
public void StartTimer(){
}

Answer 1

这里有很多解决方案！这在一定程度上取决于你的需求。在你的情况下，最喜欢的可能是

您可以使用Coroutine

public void OnCollisionEnter2D(Collision2D col) //player collide with bonus
{
if (col.gameObject.name == "Cube")
{    
StartCoroutine (Timer());
}
}
private IEnumerator Timer()
{
yield return new WaitForSeconds (3f);
// Something that happens after 3 seconds
}

---

您可以直接将碰撞消息本身转换为Coroutine

public IEnumerator OnCollisionEnter2D(Collision2D col) //player collide with bonus
{
if (col.gameObject.name == "Cube")
{     
yield return new WaitForSeconds (3f);
// Something happens after 3 seconds
}
}

---

或者您可以使用Invoke在延迟后执行方法

public void OnCollisionEnter2D(Collision2D col) //player collide with bonus
{
if (col.gameObject.name == "Cube")
{     
Invoke(nameof(AfterDelay), 3f);
}
}
public void AfterDelay()
{
// Something happens after 3 seconds
}

---

查看更多选项和详细信息如何在unity 中以简单的方式使脚本等待/睡眠

---

如果启动计时器是指例如倒计时显示，那么你肯定应该使用类似的Coroutine

public Text text;
private Coroutine timer;
public void OnCollisionEnter2D(Collision2D col) //player collide with bonus
{
if (col.gameObject.name == "Cube")
{    
if(timer == null) timer = StartCoroutine (Timer(3f));
}
}
public void OnCollisionExit2D(Collision2D col) //player left bonus before timer passed
{
if (col.gameObject.name == "Cube")
{    
if(timer == null) StopCoroutine (timer);
timer = null;
}
}
private IEnumerator Timer(float durationInSeconds)
{
var timeLeft = duration;
while(timeLeft >= 0)
{
Text.text = timeLeft.ToString(F2);
yield return null;
}
// Something that happens after the timer reached 0
Debug.Log("Hello!");
}

Answer 2

1. Unity的方法是协同程序

public void OnCollisionEnter2D(Collision2D col) //player collide with bonus
{
if (col.gameObject.name == "Cube")
{
StartCoroutine(MyTimer());
}
}
IEnumerator StartTimer(){
yield return new WaitForSeconds(3f);
// DO STUFF AFTER 3 SECONDS
}

2. 您可以创建一个RunDelayed帮助程序来简化语法。到目前为止我最喜欢的。它使代码看起来更干净。阅读我关于这一点的博客文章，以及如何在所有的单行为中(通过继承或扩展方法(访问它

public void OnCollisionEnter2D(Collision2D col) //player collide with bonus
{
if (col.gameObject.name == "Cube")
{
RunDelayd(3f, () => {
// DO STUFF HERE AFTER 3 SECONDS
});
}
}
protected IEnumerator DelayedCoroutine(float delay, System.Action a)
{
yield return new WaitForSeconds(delay);
a();
}
protected Coroutine RunDelayed(float delay, System.Action a)
{
return StartCoroutine(DelayedCoroutine(delay, a));
}

3. 您可以使用C#任务和后台线程。在Unity中，我尽量避免使用它们，因为它们与WebGL不兼容，你可能会在玩家中遇到问题。我知道谷歌的Firebase使用它们，所以对于更复杂的异步任务，值得一看。对于你的简单案例，我不推荐他们