Unity教程（十六）敌人攻击状态的实现

Unity开发2D类银河恶魔城游戏学习笔记

Unity教程（零）Unity和VS的使用相关内容
Unity教程（一）开始学习状态机
Unity教程（二）角色移动的实现
Unity教程（三）角色跳跃的实现
Unity教程（四）碰撞检测
Unity教程（五）角色冲刺的实现
Unity教程（六）角色滑墙的实现
Unity教程（七）角色蹬墙跳的实现
Unity教程（八）角色攻击的基本实现
Unity教程（九）角色攻击的改进

Unity教程（十）Tile Palette搭建平台关卡
Unity教程（十一）相机
Unity教程（十二）视差背景

Unity教程（十三）敌人状态机
Unity教程（十四）敌人空闲和移动的实现
Unity教程（十五）敌人战斗状态的实现
Unity教程（十六）敌人攻击状态的实现
Unity教程（十七）敌人战斗状态的完善

如果你更习惯用知乎
Unity开发2D类银河恶魔城游戏学习笔记目录

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前言

本文为Udemy课程The Ultimate Guide to Creating an RPG Game in Unity学习笔记，如有错误，欢迎指正。

本节实现敌人的攻击状态。

Udemy课程地址

对应视频：
Enemy’s Attack State

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一、概述

在骷髅进入战斗状态并走到距离玩家很近的距离时，就要进入攻击状态攻击玩家。本节中我们就实现骷髅的攻击状态。
这一部分状态转换条件较多，如下图：

二、创建骷髅攻击动画

我们创建动画skeletonAttack
层次面板中选中Enemy_skeleton下的Animator，在Animation面板中创建动画
将精灵表SkeletonAttack内容全部拖入，采样率改为15
动画创建的更详细讲解见Unity教程（零）Unity和VS的使用相关内容

连接状态机，并添加过渡条件Attack，并修改过渡设置
添加bool型条件变量Attack，并连接过渡

Entry->skeletonAttack的过渡,加条件变量

skeletonAttack->Exit的过渡,加条件变量，并更改设置

三、骷髅攻击的实现

（1）整理代码

上一节我们用到了很多次骷髅的速度，所以我们在敌人状态中创建刚体，使代码更简洁。

protected Rigidbody2D rb;public virtual void Enter(){rb = enemyBase.rb;triggerCalled = false;enemyBase.anim.SetBool(animBoolName, true);}

SkeletonBattleState状态Update函数中改为

    public override void Update(){base.Update();if (enemy.IsPlayerDetected()){if (enemy.IsPlayerDetected().distance < enemy.attackDistance){stateMachine.ChangeState(enemy.attackState);}}if(player.position.x > enemy.transform.position.x)moveDir = 1;else if(player.position.x < enemy.transform.position.x)moveDir = -1;enemy.SetVelocity(enemy.moveSpeed * moveDir, rb.velocity.y);}

SkeletonMoveState状态Update函数中改为

    public override void Update(){base.Update();enemy.SetVelocity(enemy.moveSpeed*enemy.facingDir,rb.velocity.y);if(!enemy.isGroundDetected() || enemy.isWallDetected()){enemy.Flip();stateMachine.ChangeState(enemy.idleState);}}

（2）创建SkeletonAttackState

首先创建SkeletonAttackState，它继承自EnemyState,通过菜单生成构造函数和重写。

添加Enemy_Skeleton变量，并修改构造函数中传入值

    protected Enemy_Skeleton enemy;public SkeletonAttackState(EnemyStateMachine _stateMachine, Enemy _enemyBase, Enemy_Skeleton _enemy, string _animBoolName) : base(_stateMachine, _enemyBase, _animBoolName){enemy = _enemy;}

（3）触发器的实现

和Player一样，敌人攻击的结束也要借助触发器来实现。
详细讲解请见Unity教程（八）角色基本攻击的实现
我们在状态基类EnemyState中添加改变参数的函数，若触发器被调用，则triggerCalled置为真。添加代码：

    //修改触发器参数public virtual void AnimationFinishTrigger(){triggerCalled = true;}

在Enemy中进行调用

    //设置触发器public virtual void AnimationTrigger() => stateMachine.currentState.AnimationFinishTrigger();

我们创建骷髅的触发器脚本Enemy_SkeletonAnimationTriggers。获取Animator的父组件Enemy_Skeleton，并调用其中的AnimationTrigger()

//Enemy_SkeletonAnimationTriggers:触发器组件
using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class Enemy_SkeletonAnimationTriggers : MonoBehaviour
{private Enemy_Skeleton enemy => GetComponentInParent<Enemy_Skeleton>();private void AnimationTrigger(){enemy.AnimationTrigger();}
}

把触发器脚本挂在Enemy_Skeleton的Animator下面  我们在skeletonAttack的最后一帧设置事件帧，调用触发器函数设置triggerCalled参数。

先把白色竖线拉到最后一帧，点击动画面板左边钉子符号的标志添加事件。


点击选中事件帧，在右边面板选中函数AnimationTrigger
Fuction->Enemy_SkeletonAnimationTriggers->Methods->AnimationTrigger()

（4）攻击的实现

我们要在Enemy_Skeleton中创建骷髅攻击状态。

public SkeletonAttackState attackState { get; private set; }protected override void Awake()
{base.Awake();idleState = new SkeletonIdleState(stateMachine,this,this,"Idle");moveState = new SkeletonMoveState(stateMachine, this,this, "Move");battleState = new SkeletonBattleState(stateMachine, this, this, "Move");attackState = new SkeletonAttackState(stateMachine, this, this, "Attack");
}

在SkeletonBattleState中添加状态转换，当距离过近时转换到攻击状态。

    public override void Update(){base.Update();if (enemy.IsPlayerDetected()){if (enemy.IsPlayerDetected().distance < enemy.attackDistance){stateMachine.ChangeState(enemy.attackState);}}if(player.position.x > enemy.transform.position.x)moveDir = 1;else if(player.position.x < enemy.transform.position.x)moveDir = -1;enemy.SetVelocity(enemy.moveSpeed * moveDir, enemy.rb.velocity.y);}

我们在SkeletonAttackState中实现攻击的具体内容。
首先我们希望骷髅靠近玩家时，先停止移动再攻击，所以我们先把骷髅速度赋零。
在攻击动画播放完触发器被触发时，攻击结束，转换到战斗状态。

点击Animator也能看到左侧Attack变量在转换（切换很快，不仔细看不清楚）。

四、骷髅攻击的冷却

现在骷髅的攻击是连续不断的，在游戏中通常小怪是按照一定的频率进行的，让玩家有一定的躲避时间。
我们给骷髅小怪加上攻击冷却时间，实现上可以参照Player的连击。
我们在Enemy中添加冷却时间attackCoolDown，记录上次攻击的时间lastTimeAttacked用于实现。

    [Header("Attack Info")]public float attackDistance;public float attackCoolDown;[HideInInspector] public float lastTimeAttacked;

在SkeletonAttackState中，每次退出攻击状态时，更新lastTimeAttacked。

    public override void Exit(){base.Exit();enemy.lastTimeAttacked=Time.time;}

在SkeletonBattleState中添加CanAttack函数，利用现在的时间与上次攻击时间加冷却时间比较，判断冷却时间是否已经过去，骷髅是否处于可攻击状态。
先判断是否能检测到玩家，再判断玩家与骷髅的距离，再做攻击冷却的判断，条件都成立时转到战斗状态。

public override void Update(){base.Update();if (enemy.IsPlayerDetected()){if (enemy.IsPlayerDetected().distance < enemy.attackDistance){if(CanAttack())stateMachine.ChangeState(enemy.attackState);}}if(player.position.x > enemy.transform.position.x)moveDir = 1;else if(player.position.x < enemy.transform.position.x)moveDir = -1;enemy.SetVelocity(enemy.moveSpeed * moveDir, rb.velocity.y);}private bool CanAttack(){if (Time.time >= enemy.lastTimeAttacked + enemy.attackCoolDown)return true;return false;}

设置合适的冷却时间

效果如下

我们可以看到骷髅每隔一段时间进行攻击了。但是有个很明显的问题，在攻击的间隙骷髅不会停止移动，玩家会被推着走。这个问题下节我们再来解决。

总结 完整代码

EnemyState.cs

增加刚体和触发函数调用

//EnemyState:敌人状态基类
using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class EnemyState
{protected EnemyStateMachine stateMachine;protected Enemy enemyBase;protected Rigidbody2D rb;private string animBoolName;protected float stateTimer;protected bool triggerCalled;//构造函数public EnemyState(EnemyStateMachine _stateMachine, Enemy _enemyBase, string _animBoolName){this.stateMachine = _stateMachine;this.enemyBase = _enemyBase;this.animBoolName = _animBoolName;}public virtual void Enter(){rb = enemyBase.rb;triggerCalled = false;enemyBase.anim.SetBool(animBoolName, true);}public virtual void Update(){stateTimer-= Time.deltaTime;}public virtual void Exit(){enemyBase.anim.SetBool(animBoolName, false);}//修改触发器参数public virtual void AnimationFinishTrigger(){triggerCalled = true;}
}

Enemy.cs

添加攻击相关变量，添加触发函数调用。

//Enemy:敌人基类
using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class Enemy : Entity
{[SerializeField] protected LayerMask WhatIsPlayer;[Header("Move Info")]public float moveSpeed = 1.5f;public float idleTime = 2.0f;[Header("Attack Info")]public float attackDistance;public float attackCoolDown;[HideInInspector] public float lastTimeAttacked;public EnemyStateMachine stateMachine;protected override void Awake(){base.Awake();stateMachine = new EnemyStateMachine();}protected override void Update(){base.Update();stateMachine.currentState.Update();}//设置触发器public virtual void AnimationTrigger() => stateMachine.currentState.AnimationFinishTrigger();public virtual RaycastHit2D IsPlayerDetected()=>Physics2D.Raycast(transform.position, Vector2.right * facingDir, 50 ,WhatIsPlayer);protected override void OnDrawGizmos(){base.OnDrawGizmos();Gizmos.color = Color.yellow;Gizmos.DrawLine(transform.position, new Vector3(transform.position.x + attackDistance * facingDir, transform.position.y));}
}

Enemy_SkeletonAnimationTriggers.cs

触发器组件

//Enemy_SkeletonAnimationTriggers:触发器组件
using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class Enemy_SkeletonAnimationTriggers : MonoBehaviour
{private Enemy_Skeleton enemy => GetComponentInParent<Enemy_Skeleton>();private void AnimationTrigger(){enemy.AnimationTrigger();}
}

Enemy_Skeleton.cs

增加攻击状态创建

//Enemy_Skeleton:骷髅敌人
using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class Enemy_Skeleton : Enemy
{#region 状态public SkeletonIdleState idleState { get; private set; }public SkeletonMoveState moveState { get; private set; }public SkeletonBattleState battleState { get; private set; }public SkeletonAttackState attackState { get; private set; }#endregionprotected override void Awake(){base.Awake();idleState = new SkeletonIdleState(stateMachine,this,this,"Idle");moveState = new SkeletonMoveState(stateMachine, this,this, "Move");battleState = new SkeletonBattleState(stateMachine, this, this, "Move");attackState = new SkeletonAttackState(stateMachine, this, this, "Attack");}protected override void Start(){base.Start();stateMachine.Initialize(idleState);}protected override void Update(){base.Update();}}

SkeletonBattleState.cs

添加攻击冷却判断条件，修改转到攻击状态的条件，修改刚体速度部分代码

//SkeletonBattleState:骷髅战斗状态
using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class SkeletonBattleState : EnemyState
{private Transform player;private Enemy_Skeleton enemy;private int moveDir;public SkeletonBattleState(EnemyStateMachine _stateMachine, Enemy _enemyBase, Enemy_Skeleton _enemy, string _animBoolName) : base(_stateMachine, _enemyBase, _animBoolName){enemy=_enemy;}public override void Enter(){base.Enter();player = GameObject.Find("Player").transform;}public override void Exit(){base.Exit();}public override void Update(){base.Update();if (enemy.IsPlayerDetected()){if (enemy.IsPlayerDetected().distance < enemy.attackDistance){if(CanAttack())stateMachine.ChangeState(enemy.attackState);}}if(player.position.x > enemy.transform.position.x)moveDir = 1;else if(player.position.x < enemy.transform.position.x)moveDir = -1;enemy.SetVelocity(enemy.moveSpeed * moveDir, rb.velocity.y);}private bool CanAttack(){if (Time.time >= enemy.lastTimeAttacked + enemy.attackCoolDown)return true;return false;}
}

SkeletonAttackState.cs

创建攻击状态，攻击时速度置零，触发器触发转回到战斗状态

//SkeletonAttackState:骷髅攻击状态
using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class SkeletonAttackState : EnemyState
{protected Enemy_Skeleton enemy;public SkeletonAttackState(EnemyStateMachine _stateMachine, Enemy _enemyBase, Enemy_Skeleton _enemy, string _animBoolName) : base(_stateMachine, _enemyBase, _animBoolName){enemy = _enemy;}public override void Enter(){base.Enter();}public override void Exit(){base.Exit();enemy.lastTimeAttacked=Time.time;}public override void Update(){base.Update();enemy.ZeroVelocity();if (triggerCalled)stateMachine.ChangeState(enemy.battleState);}
}

SkeletonMoveState.cs

修改刚体速度部分代码

//SkeletonMoveState:骷髅移动状态
using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class SkeletonMoveState : SkeletonGroundedState
{public SkeletonMoveState(EnemyStateMachine _stateMachine, Enemy _enemyBase, Enemy_Skeleton enemy, string _animBoolName) : base(_stateMachine, _enemyBase, enemy, _animBoolName){}public override void Enter(){base.Enter();}public override void Exit(){base.Exit();}public override void Update(){base.Update();enemy.SetVelocity(enemy.moveSpeed*enemy.facingDir,rb.velocity.y);if(!enemy.isGroundDetected() || enemy.isWallDetected()){enemy.Flip();stateMachine.ChangeState(enemy.idleState);}}
}