Unity学习笔记（2）飞机大战第二章

一、实现效果

效果图

功能列表

1. 飞机定时无限发射
2. 左右键控制飞机左右移动
3. 随机生成怪物，怪物有不同
4. 子弹射中怪物后，子弹和怪物一起被摧毁

二、知识点

刚体

• Dynamic 普通刚体 有质量
• Static 静态刚体 质量无穷（地面）
• Kinematic 运动学刚体 质量为0（物理规律不起作用，一般用于碰撞检测）
• 设置刚体：Physics 2D ->RigidBody 2D -> Body Type -> Dynamic/Static/Kinematic

碰撞体

• Physics 2D -> Box/Circle Collider 2D -> is Trigger

碰撞检测

• 设置可碰撞：添加碰撞组件Physics 2D ->Box Collider2D->is Trigger 打勾
• 添加碰撞检测函数(例)：
  private void OnTriggerEnter2D(Collider2D collision){Debug.Log("检测到了碰撞");}

Collider2D collision表示对方的碰撞组件
collision.gameObject——对方
collision.name——对方节点名称
collision.tag —— 对方的节点的Tag
collision.transform——对方的Transform组件

• 碰撞事件回调：
  1、OnTriggerEnter2D,两碰撞体开始相遇
  2、OnTriggerStay2D,两碰撞体接触中
  3、OnTriggerExit2D,两碰撞体离开

随机数

value=Random.Range(min,max);
eg:float x=Random.Range(-2,2);

定时器

InvokeRepeating(method, delay,interval);//delay 多长时间后执行第一次，interval 几秒钟重复一次方法调用
eg:InvokeRepeating(“CreatePig”,0.1f ,2f);

随机选择图片

int index = Random.Range(0, images.Length);
SpriteRenderer renderer = monster.GetComponent();
renderer.sprite = this.images[index];

三、代码实现

MyGame.cs

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

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

    // Update is called once per frame
    void Update()
    {
        
    }
}

MyBullet.cs

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

public class MyBullet : MonoBehaviour
{
    public float speed = 2.0f;
    // Start is called before the first frame update
    void Start()
    {
        
    }

    // Update is called once per frame
    void Update()
    {
        float dy = speed * Time.deltaTime;
        transform.Translate(0, dy, 0, Space.Self);
        Vector3 sp = Camera.main.WorldToScreenPoint(transform.position);
        if(sp.y>Screen.height)
        {
            Destroy(this.gameObject);
        }
    }
    private void OnTriggerEnter2D(Collider2D collision)
    {
        if(collision.tag.Equals("Monster"))
        {
            Destroy(collision.gameObject);
            Destroy(this.gameObject);
        }
    }
}

MyJet.cs

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

public class MyJet : MonoBehaviour
{
    public float speed = 2.0f;
    public GameObject bulletPrefab;

    private float count = 0;
    private float interval = 0.4f;
    // Start is called before the first frame update
    void Start()
    {
        
    }

    // Update is called once per frame
    void Update()
    {
        count += Time.deltaTime;
        if(count >interval )
        {
            count = 0;
            Fire();
        }
        float step = speed * Time.deltaTime;
        if(Input.GetKey(KeyCode.LeftArrow))
        {
            transform.Translate(-step, 0, 0);
        }
        if (Input.GetKey(KeyCode.RightArrow))
        {
            transform.Translate(step, 0, 0);
        }

    }
    void Fire()
    {
        Vector3 pos = transform.position + new Vector3(0, 1, 0);
        GameObject bullet = Instantiate(bulletPrefab, pos, transform.rotation);

    }
}

Monster.cs

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

public class Monster : MonoBehaviour
{
    public float speed = 1.0f;
    // Start is called before the first frame update
    void Start()
    {
        
    }

    // Update is called once per frame
    void Update()
    {
        float dy = speed * Time.deltaTime;
        transform.Translate(0, -dy, 0, Space.Self);
        Vector3 sp = Camera.main.WorldToScreenPoint(transform.position);
        if (-sp.y*2 > Screen.height)
        {
            Destroy(this.gameObject);
        }
    }
}

MonsterCtrl.cs

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

public class MonsterCtrl : MonoBehaviour
{
    public GameObject MonsterPrefab;
    public Sprite[] images;
    // Start is called before the first frame update
    void Start()
    {
        InvokeRepeating("CreateMonster", 0.1f, 2f);
    }

    // Update is called once per frame
    void Update()
    {
        
    }
    void CreateMonster()
    {
        float x = Random.Range(-2, 2);
        float y = 5;
        GameObject monster = Instantiate(MonsterPrefab);
        monster.transform.position = new Vector3(x, y, 0);
        //
        int index = Random.Range(0, images.Length);//6张图片
        SpriteRenderer renderer = monster.GetComponent<SpriteRenderer>();
        renderer.sprite = this.images[index];
        
    }
}

四、遇到了一个非常头疼的问题

报错: The object of type ‘xxx’ has been destroyed but you are still trying to access it

但我的逻辑明明没有错误，也是照着老师的步骤来的，怎么会在摧毁上一个预制体后不能成功创建下一个预制体呢？？？？？然后搜索了很多，怀疑是因为程序调用的时候虽然逻辑上预制体被摧毁了，但其实程序滞留，在创建预制体时访问的是上一个空的预制体，所以访问不了。woc，这啥呀这是，关键是人家老师为啥能行，我就不行，我电脑可是apple M1啊，按道理cpu速度也是行的啊???

皆大欢喜！！！！??????解决了！！！
我是sabi叭，完全是因为预制体移错了，贴图警告⚠️

不知道为什么，当路径二的怪物变蓝后我就自认为它就变成预制体了，但其实并不是，只能从Prefab的文件夹中移出，也不能这样说，总的来说是要看准到底谁是预制体。