Vector3.sqrMagnitude 长度平方

# [Vector3](Vector3.html).sqrMagnitude 长度平方

var *sqrMagnitude* : float

*Description* 描述

Returns the squared length of this vector (Read Only).

返回这个向量的长度的平方（只读）。

Calculating the squared magnitude instead of the [magnitude](Vector3.magnitude.html) is much faster. Often if you are
comparing magnitudes of two vectors you can just compare their squared
magnitudes.

计算长度的平方而不是 [magnitude](Vector3.magnitude.html) 是非常快的。如果你是比较两个向量的长度差，你可以比较他们的平方长度。

> 向量的长度是用勾股定理计算出来，计算机计算两次方和开根的运算量比加减法要费时的多。所以如果是想比较两个向量的长度，用 sqrMagnitude 可以快出很多。

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

```
using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
	public Transform other;
	public float closeDistance = 5.0F;
	void Update() {
		if (typeof(other)) {
			float sqrLen = other.position - transform.position.sqrMagnitude;
			if (sqrLen < closeDistance * closeDistance)
				print("The other transform is close to me!");

}
	}
}
```

```
// detects when the other transform is closer than closeDistance
// this is faster than using Vector3.magnitude
//当其他变换比closeDistance更近时检测
//这比使用Vector3.magnitude更快
var other : Transform;
var closeDistance = 5.0;

function Update() {
	if (other) {
		var sqrLen = (other.position - transform.position).sqrMagnitude;
		// square the distance we compare with
		//我们比较距离的平方
		if( sqrLen < closeDistance*closeDistance )
			print ("The other transform is close to me!");
	}
}
```

参见： [magnitude](Vector3.magnitude.html).