using UnityEngine;

using System.Collections;

public class ProjectileTest : MonoBehaviour{

    public GameObject target; //要到达的目标

    public float speed = 10;    //速度

    private float distanceToTarget;  //两者之间的距离

    private bool IsMove = true; //判断是否到达位置

    void Start ()  {

        distanceToTarget = Vector3.Distance (this.transform.position, target.transform.position);

        StartCoroutine (Shoot ());

    }

    IEnumerator Shoot ()

    {

        while (move) {

            Vector3 targetPos = target.transform.position;

            this.transform.LookAt (targetPos);

            float angle = Mathf.Min (1, Vector3.Distance (this.transform.position, targetPos) / distanceToTarget) * 45;

            this.transform.rotation = this.transform.rotation * Quaternion.Euler (Mathf.Clamp (-angle, -42, 42), 0, 0);

            float currentDist = Vector3.Distance (this.transform.position, target.transform.position);

            print ("currentDist" + currentDist);

            if (currentDist < 0.5f)

                move = false;

            this.transform.Translate (Vector3.forward * Mathf.Min (speed * Time.deltaTime, currentDist));

            yield return null;

        }

    }

}