U3D 实现子弹发射效果

using UnityEngine;
using System.Collections;

public class gun : MonoBehaviour {

public Rigidbody2D rocket;
public float speed;
// Use this for initialization

void Start () {

}

// Update is called once per frame
void Update () {
if(Input.GetKey(KeyCode.K)){
不断的实例化子弹刚体，并让其向前运动。
Rigidbody2D bullet = Instantiate(rocket,transform.position,Quaternion.Euler(new Vector3(0,0,0))) as Rigidbody2D;
//使刚体运动 Y方向为0
bullet.velocity = new Vector2(speed,0);

}
}
}