Collider2D.OnTriggerEnter2D(Collider2D)

# [Collider2D](https://docs.unity3d.com/cn/2019.4/ScriptReference/Collider2D.html).OnTriggerEnter2D(Collider2D)

## 参数

| other | 该碰撞中涉及的其他 [Collider2D](https://docs.unity3d.com/cn/2019.4/ScriptReference/Collider2D.html)。 |
| ------- | ---------------------------------------------------------------------------------------------------- |

## 描述

当另一个对象进入附加到该对象的触发碰撞体时发送（仅限 2D 物理）。

在调用期间传入的 [Collider2D](https://docs.unity3d.com/cn/2019.4/ScriptReference/Collider2D.html) 参数中报告有关其他碰撞体的进一步信息。

触发器事件将发送到已禁用的 [MonoBehaviour](https://docs.unity3d.com/cn/2019.4/ScriptReference/MonoBehaviour.html)s，以便允许启用 [Behaviour](https://docs.unity3d.com/cn/2019.4/ScriptReference/Behaviour.html)s，以响应碰撞。

请参阅：[Collider2D](https://docs.unity3d.com/cn/2019.4/ScriptReference/Collider2D.html) 类以及 [OnTriggerExit2D](https://docs.unity3d.com/cn/2019.4/ScriptReference/Collider2D.OnTriggerExit2D.html) 和 [OnTriggerStay2D](https://docs.unity3d.com/cn/2019.4/ScriptReference/Collider2D.OnTriggerStay2D.html) 消息。

此处显示了一个 [OnTriggerEnter2D](https://docs.unity3d.com/cn/2019.4/ScriptReference/Collider2D.OnTriggerEnter2D.html) 示例。此示例有两个空的 [GameObject](https://docs.unity3d.com/cn/2019.4/ScriptReference/GameObject.html)，分别名为 `GameObject1` 和 /GameObject2/。这两个游戏对象都有脚本文件能使本示例正常工作。第一个脚本是 /Example1/，用于创建 [Sprite](https://docs.unity3d.com/cn/2019.4/ScriptReference/Sprite.html) 并添加 [BoxCollider2D](https://docs.unity3d.com/cn/2019.4/ScriptReference/BoxCollider2D.html) 和 [Rigidbody2D](https://docs.unity3d.com/cn/2019.4/ScriptReference/Rigidbody2D.html)。此对象受重力下落并与 `Example2` 发生碰撞。`Example2` 无法看到显示效果。（它创建的矩形在 Scene 窗口中可见。）这两个 [GameObject](https://docs.unity3d.com/cn/2019.4/ScriptReference/GameObject.html) 都会报告碰撞。

以下脚本是 Example1。

```
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

// Create GameObject1 that falls under gravity.  It will pass through
// Example2 and cause a collision.  GameObject1 is moved back to
// the start position and it will again start to fall under gravity.

public class Example1 : MonoBehaviour
{
    void Awake()
    {
        SpriteRenderer sr;
        sr = gameObject.AddComponent<SpriteRenderer>() as SpriteRenderer;
        sr.color = new Color(0.9f, 0.9f, 0.1f, 1.0f);

BoxCollider2D bc;
        bc = gameObject.AddComponent<BoxCollider2D>() as BoxCollider2D;
        bc.size = new Vector2(1.0f, 1.0f);

Rigidbody2D rb;
        rb = gameObject.AddComponent<Rigidbody2D>() as Rigidbody2D;
        rb.gravityScale = 1.0f;

// A square in the Resources folder is used.
        gameObject.GetComponent<SpriteRenderer>().sprite = Resources.Load<Sprite>("square");

// GameObject1 starts 3 units in the Up direction.
        gameObject.transform.position = new Vector3(0.0f, 3.0f, 0.0f);
        gameObject.transform.localScale = new Vector3(0.5f, 0.5f, 1.0f);
    }

private float timer = 0.0f;
    private bool restart = false;

void FixedUpdate()
    {
        if (restart == true)
        {
            timer = timer + Time.deltaTime;
            if (timer > 0.25f)
            {
                gameObject.transform.position = new Vector3(0.0f, 3.0f, 0.0f);
                gameObject.GetComponent<Rigidbody2D>().velocity = new Vector2(0.0f, 0.0f);
                restart = false;
            }
        }
    }

// called when this GameObject collides with GameObject2.
    void OnTriggerEnter2D(Collider2D col)
    {
        Debug.Log("GameObject1 collided with " + col.name);
        restart = true;
        timer = 0.0f;
    }
}
```

这是 /Example2/，即第二个 [GameObject](https://docs.unity3d.com/cn/2019.4/ScriptReference/GameObject.html) 的碰撞脚本：

```
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

// Create a rectangle that the other GameObject will collide with.
// Note that this GameObject has no visibility.
// (View in the Scene view to see this GameObject.)

public class Example2 : MonoBehaviour
{
    void Awake()
    {
        BoxCollider2D bc;
        bc = gameObject.AddComponent<BoxCollider2D>() as BoxCollider2D;
        bc.size = new Vector2(3.0f, 1.0f);
        bc.isTrigger = true;

gameObject.transform.localScale = new Vector3(3.0f, 1.0f, 1.0f);
        gameObject.transform.position = new Vector3(0.0f, -2.0f, 0.0f);
    }

void OnTriggerEnter2D(Collider2D col)
    {
        Debug.Log("GameObject2 collided with " + col.name);
    }
}
```