Overview: Coroutines & Yield 协同程序 & 中断
When writing game code, one often ends up needing to script a sequence of events. This could result in code like the following.
写游戏代码,往往最终需要代码为连续的事件.结果会像这样:
using UnityEngine;
using System.Collections;
public class example : MonoBehaviour {
private int state = 0;
void Update() {
if (state == 0) {
state = 1;
return;
}
if (state == 1) {
state = 2;
return;
}
}
}private var state = 0;
function Update() {
if (state == 0) {
// do step 0 //做步骤0
state = 1;
return;
}
if (state == 1) {
// do step 1 // 做步骤1
state = 2;
return;
}
// ...
}It is often more convenient to use the yield statement. The yield statement is a special kind of return, that ensures that the function will continue from the line after the yield statement next time it is called.
往往使用中断语句更为方便.中断语句是一个特殊的返回类型,它确保函数从中断语句的下一行继续执行.
using UnityEngine;
using System.Collections;
public class example : MonoBehaviour {
IEnumerator Awake() {
while (true) {
yield return null;
yield return null;
}
}
}while(true) {
// do step 0 // 做步骤0
yield;
// wait for one frame
// do step 1
// 等待一帧
// 做步骤1
yield;
// wait for one frame
// 等待一帧
// ...
}You can also pass special values to the yield statement to delay the execution of the Update function until a certain event has occurred.
你也可以传递时间值到中断语句,Update函数会在中断时间结束后执行下一语句.
using UnityEngine;
using System.Collections;
public class example : MonoBehaviour {
IEnumerator Awake() {
yield return new WaitForSeconds(5.0F);
}
}// do something
yield WaitForSeconds (5.0); // wait for 5 seconds等待5秒
// do something
more...You can both stack and chain coroutines.
你能叠加和连接协同程序.
This example will execute Do but continue after calling do immediately.
这个例子将执行Do,但是do函数之后的print指令会立刻执行.
using UnityEngine;
using System.Collections;
public class example : MonoBehaviour {
IEnumerator Do() {
print("Do now");
yield return new WaitForSeconds(2);
print("Do 2 seconds later");
}
void Awake() {
Do();
print("This is printed immediately");
}
}Do ();
print ("This is printed immediately");
function Do (){
print("Do now");
yield WaitForSeconds (2);
print("Do 2 seconds later");
}
This example will execute Do and wait until it is finished before continuing its own execution
这个例子将执行Do,并等待,直到Do完成再执行其他语句.
using UnityEngine;
using System.Collections;
public class example : MonoBehaviour {
IEnumerator Do() {
print("Do now");
yield return new WaitForSeconds(2);
print("Do 2 seconds later");
}
IEnumerator Awake() {
yield return StartCoroutine("Do");
print("Also after 2 seconds");
print("This is after the Do coroutine has finished execution");
}
}// chain the coroutine
// 连接协同程序
yield StartCoroutine("Do");
print("Also after 2 seconds");
print ("This is after the Do coroutine has finished execution");
function Do (){
print("Do now");
yield WaitForSeconds (2);
print("Do 2 seconds later");
}Any event handler can also be a coroutine.
任何事件处理程序都可以是协同程序
Note that you can't use yield from within Update or FixedUpdate, but you can use StartCoroutine to start a function that can.
注意你不能在Update或FixedUpdate函数内使用中断,但是你能使用 StartCoroutine 开始一个函数.
查看 YieldInstruction, WaitForSeconds, WaitForFixedUpdate, Coroutine and MonoBehaviour.StartCoroutine 可以获得更多使用中断的信息.