Alex教程每一P的教程原代码加上我自己的理解初步理解写的注释，可供学习Alex教程的人参考
此代码仅为较上一P有所改变的代码

【Unity教程】从0编程制作类银河恶魔城游戏_哔哩哔哩_bilibili

PlayerManager.cs

using System.Collections;
using System.Collections.Generic;
using Unity.VisualScripting;
using UnityEngine;

public class PlayerManager : MonoBehaviour
{
    public static PlayerManager instance;
    public Player player;//这是通过在外部设置了一个组件，让这个组件能够直接把Player找到，从而减少FInd的方式所带来的高负载

    private void Awake()
    {
        if(instance != null)
        {
            Destroy(instance.gameObject);
        }
        else
        instance = this;
    }
}

SkillManager.cs

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

public class SkillManager : MonoBehaviour
{
    public static SkillManager instance;
    private void Awake()
    {
        if (instance != null)
        {
            Destroy(instance.gameObject);
        }
        else
            instance = this;
    }
}

SkeletonGroundState.cs

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

public class SkeletonGroundState : EnemyState
{
    protected Enemy_Skeleton enemy;
    protected Transform player;
    public SkeletonGroundState(Enemy _enemyBase, EnemyStateMachine _stateMachine, string _animBoolName,Enemy_Skeleton _enemy) : base(_enemyBase, _stateMachine, _animBoolName)
    {
        enemy = _enemy;
    }

    public override void Enter()
    {
        base.Enter();
        player = PlayerManager.instance.player.transform;

    }

    public override void Exit()
    {
        base.Exit();
    }

    public override void Update()
    {
        base.Update();

        if(enemy.IsPlayerDetected()||Vector2.Distance(enemy.transform.position,player.transform.position)<2)
        {
            stateMachine.ChangeState(enemy.battleState);
        }
    }
}

SkeletonBattleState.cs

using System.Collections;
using System.Collections.Generic;
using TMPro;
using UnityEngine;
//从ground进来的
public class SkeletonBattleState : EnemyState
{
    private Transform player;//用于给Player定位，好判断怎么跟上他
    private Enemy_Skeleton enemy;
    private int moveDir;
    public SkeletonBattleState(Enemy _enemyBase, EnemyStateMachine _stateMachine, string _animBoolName,Enemy_Skeleton _enemy ) : base(_enemyBase, _stateMachine, _animBoolName)
    {
        enemy = _enemy;
    }

    public override void Enter()
    {
        base.Enter();
        
        //player = GameObject.Find("Player").transform;//全局找Player位置
        player = PlayerManager.instance.player.transform;
    }

    public override void Exit()
    {
        base.Exit();
    }

    public override void Update()
    {
        base.Update();
        //退出此状态的方式
        if(enemy.IsPlayerDetected())
        {
            stateTimer = enemy.battleTime;
            if (enemy.IsPlayerDetected().distance < enemy.attackDistance)//当距离小于攻击距离，变为攻击状态
            {
                if (CanAttack())
                    stateMachine.ChangeState(enemy.attackState);
            }
        }
        else//当没有看见player后，才会根据没有看到的时间来使其退出battle状态
        {
            if(stateTimer < 0||Vector2.Distance(player.transform.position,enemy.transform.position)>7)//根据距离来判断是否结束battle状态
            {
                stateMachine.ChangeState(enemy.idleState);
            }
        }
        

        //下面为移动方向设置
        if(player.position.x > enemy.transform.position.x)//在右，向右移动
        {
            moveDir = 1;
        }
        else if(player.position.x<enemy.transform.position.x)//在左，向左移动
        {
            moveDir = -1;
        }

        if(Vector2.Distance(player.transform.position,enemy.transform.position)>1)
        enemy.SetVelocity(enemy.moveSpeed * moveDir, rb.velocity.y);
        else
        {
            enemy.SetZeroVelocity();
        }//我自己设置了一个敌人接近一定距离就停下来的设置，防止出现敌人乱晃的情况
    }

    private bool CanAttack()
    {
        if(Time.time > enemy.lastTimeAttacked + enemy.attackCooldown)
        {
            enemy.lastTimeAttacked = Time.time;
            return true;
        }
        
        return false;
    }
}