Input.GetButtonDown 获取按钮按下

# [Input](Input.html).GetButtonDown 获取按钮按下

static function *GetButtonDown* (*buttonName* : string) : bool

*Description* 描述

Returns true during the frame the user pressed down the virtual button
identified by buttonName.

在给定名称的虚拟按钮被按下的那一帧返回 true。

You need to call this function from the [Update](../MonoBehaviour/MonoBehaviour.Update.html) function, since the
state gets reset each frame. It will not return true until the user has released
the key and pressed it again.

你需要在 Update 方法中调用这个方法，此后每一帧重置状态时，它将不会返回 true 除非用户释放此按键然后重新按下。

Use this only when implementing action like events IE: shooting a weapon. Use
[Input.GetAxis](Input.GetAxis.html) for any kind of movement
behaviour.

只有当执行像武器射击这样的事件时才可用此方法，Input.GetAxis 适用于各种运动行为。

* [C#](#)
* [JavaScript](#)

```
using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
	public GameObject projectile;
	void Update() {
		if (Input.GetButtonDown("Fire1"))
			Instantiate(projectile, transform.position, transform.rotation);

}
}
```

```
// Instantiates a projectile whenever the user hits the Fire1 Button.
//实例化一个发射在每次用户点击Fire1按钮时

var projectile : GameObject;
	function Update () {
	if (Input.GetButtonDown ("Fire1")) {
		Instantiate (projectile, transform.position, transform.rotation);
	}
}
```