Unity 사격 게임 커서 자동 조준 실현

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class Target : MonoBehaviour {

    public Transform source;
    public GameObject destination = null;

    public static Target Instance;
    void Awake() {
        if (Instance == null)
            Instance = this;
        else if (Instance != this)
            Destroy(gameObject);
    }
    GameObject[] enemy;
    Vector3 minDestance;
    float minDes = float.MaxValue;
    void Update() {
        enemy = GameObject.FindGameObjectsWithTag("Enemy"); //     
        foreach (var item in enemy) {
            Vector3 targetDir = source.position - item.transform.position; //              
            float angle = Vector3.Angle(-source.forward, targetDir); //               
            //    10 
            if (angle > 10) {
                minDestance = new Vector3(0, 0, 0);
                continue;
            }
            float DesX = source.position.x - item.transform.position.x;
            float DesY = source.position.y - item.transform.position.y;
            float DesZ = source.position.z - item.transform.position.z;
            //      
            if (DesZ > 500) {
                minDestance = new Vector3(0, 0, 0);
                continue;
            }
            Vector3 temp = new Vector3(DesX, DesY, DesZ);
            float min = (source.position - temp).sqrMagnitude;
            //      
            if (min < minDes) {
                minDes = min;
                minDestance = temp;
                destination = item;
            }
        }

        float ratio = (source.position.z - transform.position.z) / minDestance.z;
        if (minDestance != Vector3.zero) {
            Vector3 newPos = new Vector3(source.position.x - minDestance.x * ratio, source.position.y - minDestance.y * ratio, transform.position.z);
            transform.position = Vector3.MoveTowards(transform.position, newPos, 0.5f);
            if (destination == null) {
                minDestance = new Vector3(0, 0, 0);
            }
        }
        else {
            minDes = float.MaxValue;
            destination = null;
        }
    }
}