Vector3.Angle 角度

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
	public Transform target;
	void Update() {
		Vector3 targetDir = target.position - transform.position;
		Vector3 forward = transform.forward;
		float angle = Vector3.Angle(targetDir, forward);
		if (angle < 5.0F)
			print("close");

	}
}

// prints "close" if the z-axis of this transform looks
// almost towards the target
//如果当前变换z轴接近目标小于5度的时候，打印"close"
var target : Transform;
function Update () {
	var targetDir = target.position - transform.position;
	var forward = transform.forward;
	var angle = Vector3.Angle(targetDir, forward);
	if (angle < 5.0)
		print("close");
}