unity3d 判断目标物体对于我的方向

using UnityEngine;
using System.Collections;

public class D2 : MonoBehaviour {
public Transform targetTF;
void Start () {

}

void Update () {
checkTargetDirForMe (targetTF);
}

void checkTargetDirForMe(Transform target){
Vector3 dir = target.position - transform.position;
Vector3 cross = Vector3.Cross (transform.forward,dir.normalized);
float dot = Vector3.Dot (transform.forward,dir.normalized);
string dirText = "";
if (cross.y > 0) {
dirText += "右";
} else if(cross.y < 0) {
dirText += "左";
}else {
dirText += "正";
}
if (dot > 0) {
dirText += "上";
} else if(dot < 0) {
dirText += "下";
}else {
dirText += "中";
}
print (dirText);
}
}