Vector3.sqrMagnitude 长度平方

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!");
	}
}