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);
                
		}
	}
}