子弹发射

要求：

定时发送子弹
通过键盘控制左右移动

定时器：每0.4s发射一个子弹

定时发射子弹，通过预制体不断地创建新的“子弹”实例。
子弹发射后，沿着y轴一直移动，超出屏幕边界后销毁。
游戏对象：飞机，子弹(预制体)

“飞机” 挂载：MyJet.cs

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

public class MyJet : MonoBehaviour
{
    // 预制体资源 '子弹'
    public GameObject myPrefab;
    //注：此处一定要在Inspector面板中为 myPrefab 添加资源

    // 定时
    private float interval = 0.4f; // 每隔0.4秒发射一颗子弹
    private float count = 0; //表示计时

    // Start is called before the first frame update
    void Start()
    {
        Application.targetFrameRate = 60;
    }

    // Update is called once per frame
    void Update()
    {
        // 计时
        count += Time.deltaTime;
        //如果时间超过0.4秒就发射
        if (count >= interval)
        {
            count = 0;
            Fire();
        }

    }

    private void Fire()
    {
        // Instantiate()重载
        Vector3 pos = transform.position + new Vector3(0, 1f, 0);
        GameObject bullet = Instantiate(myPrefab, pos, transform.rotation);
    }
}

“子弹” 挂载： MyBullet.cs

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

public class MyBullet : MonoBehaviour
{
    // Start is called before the first frame update
    void Start()
    {        
    }
    // Update is called once per frame
    void Update()
    {
        float step = 5.5f * Time.deltaTime;

        transform.Translate(0, step, 0, Space.Self);

        Vector3 sp = Camera.main.WorldToScreenPoint(transform.position);
        if (sp.y > Screen.height)
        {
            Destroy(this.gameObject);  //此处注意不可以写this
        }
    }
}

键盘控制：实现箭头上下左右移动

Input.GetKeyDown(key) -------- 键盘按下事件
Input.GetKeyUp(key) -------- 键盘抬起事件
Input.GetKey(key) -------- 状态检查，某键是否被按下
在MyJet.cs中加一段探测左右是否被按下，若按下则随后移动

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

public class MyJet : MonoBehaviour
{
    // 预制体资源 '子弹'
    public GameObject myPrefab;

    // 定时
    private float interval = 0.4f; // 每隔0.4秒发射一颗子弹
    private float count = 0; //表示计时

    // Start is called before the first frame update
    void Start()
    {
        Application.targetFrameRate = 60;
    }

    // Update is called once per frame
    void Update()
    {
        // 计时
        count += Time.deltaTime;
        //如果时间超过0.4秒就发射
        if (count >= interval)
        {
            count = 0;
            Fire();
        }

		//键盘响应
        float step = 2.5f * Time.deltaTime;

		//向左移动
        if (Input.GetKey(KeyCode.LeftArrow))
        {
            transform.Translate(-step,0,0);
        }
        //向右移动
        if (Input.GetKey(KeyCode.RightArrow))
        {
            transform.Translate(step,0,0);
        }
		 //向上移动
        if (Input.GetKey(KeyCode.UpArrow))
        {
            transform.Translate(0,step,0);
        }
		 //向下移动
        if (Input.GetKey(KeyCode.DownArrow))
        {
            transform.Translate(0,-step,0);
        }
    }

    private void Fire()
    {
        // Instantiate()重载
        Vector3 pos = transform.position + new Vector3(0, 1f, 0);
        GameObject bullet = Instantiate(myPrefab, pos, transform.rotation);
    }
}