AI-有限狀態機（追擊，巡邏）

• 有限狀態機的基類，包含各種狀態

• using System.Collections;
  using System.Collections.Generic;
  using UnityEngine;
  
  
  public enum Transition
  {
      NullTransition=0,
      SeePlayer,
      LostPlayer
  }
  
  
  public enum StateID
  {
      NullStateID=0,
      Patrol,
      Chase
  }
  
  public abstract class FSMState
  {
      protected StateID stateID;
      public StateID ID { get { return stateID; } }
      protected Dictionary<Transition, StateID> map = new Dictionary<Transition, StateID>();
      protected FSMSystem fsm;
  
      public FSMState(FSMSystem fsm)
      {
          this.fsm = fsm;
      }
  
      public void AddTransition(Transition transition,StateID id)
      {
          if (transition==Transition.NullTransition)
          {
              Debug.LogError("不允許NullTransition");return;
          }
          if (id==StateID.NullStateID)
          {
              Debug.LogError("不允許NullStateID");return;
          }
          if (map.ContainsKey(transition))                // 判斷key是否存在
          {
              Debug.LogError("添加轉換條件的時候" + transition + "已經存在於map中");return;
          }
          map.Add(transition, id);
      }
  
      public void DeleteTransition(Transition transition)
      {
          if (transition == Transition.NullTransition)
          {
              Debug.LogError("不允許NullTransition"); return;
          }
          if (map.ContainsKey(transition)==false)                // 判斷key是否存在
          {
              Debug.LogError("刪除轉換條件的時候" + transition + "不存在於map中"); return;
          }
          map.Remove(transition);
      }
  
      public StateID GetOutputState (Transition transition)
      {
          if (map.ContainsKey(transition))
          {
              return map[transition];
          }
          return StateID.NullStateID;
      }
  
      //進入狀態之前的虛函數
      public virtual void DoBeforEntering() { }
      //離開狀態，狀態發生轉換
      public virtual void DoAfterLeaving() { }
      //抽象方法必須重寫
      public abstract void Act(GameObject gameObject);
      //判斷轉換條件
      public abstract void Reason(GameObject gameObject);
  }
  

• 控制狀態之間的轉換

• using System.Collections;
  using System.Collections.Generic;
  using UnityEngine;
  
  public class FSMSystem
  {
      private Dictionary<StateID, FSMState> states=new Dictionary<StateID, FSMState>();
  
      private StateID currentStateID;
      private FSMState currentState;
  
      public void AddState(FSMState s)
      {
          if (s==null)
          {
              Debug.LogError("FSMState不能爲空");return;
          }
              //默認狀態
          if (currentState==null)
          {
              currentState = s;
              currentStateID = s.ID;
          }
          //添加到字典裏
          if (states.ContainsKey(s.ID))
          {
              Debug.LogError("狀態" + s.ID + "已經存在");return;
          }
          states.Add(s.ID, s);
      }
  
      public void DeleteState(StateID id)
      {
          if (id==StateID.NullStateID)
          {
              Debug.LogError("無法刪除空狀態");return;
          }
          if (states.ContainsKey(id)==false)
          {
              Debug.LogError("無法刪除不存在的：" + id);return;
          }
          states.Remove(id);
      }
  
      //根據條件進行狀態切換
      public void PerformTransition(Transition transition)
      {
          if (transition ==Transition.NullTransition)
          {
              Debug.LogError("無法執行空的轉換條件");return;
          }
          StateID id = currentState.GetOutputState(transition);
  
          if (id==StateID.NullStateID)
          {
              Debug.LogWarning("當前狀態" + currentStateID + "無法根據轉換條件" + transition + "發生轉換");return;
          }
          FSMState fSMState = states[id];
  
          currentState.DoAfterLeaving();          //舊狀態離開
          currentState = fSMState;
          currentStateID = id;
          currentState.DoBeforEntering();         //新狀態進入
      }
  
      //調用Act方法
      public void Update(GameObject gameObject)
      {
          currentState.Act(gameObject);
          currentState.Reason(gameObject);
      }
  
  }
  

• 敵人類

• using System.Collections;
  using System.Collections.Generic;
  using UnityEngine;
  
  public class Enemy : MonoBehaviour {
  
      private FSMSystem fsm;
  	
  	void Start () {
          InitFSM();
  	}
  	
  	//對有限狀態機進行初始化
      private void InitFSM()
      {
          fsm = new FSMSystem();
          FSMState patrolState = new PatrolState(fsm);
          //轉換條件
          patrolState.AddTransition(Transition.SeePlayer,StateID.Chase);
  
          FSMState chaseState = new ChaseState(fsm);
          chaseState.AddTransition(Transition.LostPlayer, StateID.Patrol);
  
          fsm.AddState(patrolState);
          fsm.AddState(chaseState);
      }
  
  	void Update () {
          fsm.Update(this.gameObject);
  	}
  }
  

• 巡邏狀態和追擊狀態

• using System.Collections;
  using System.Collections.Generic;
  using UnityEngine;
  
  public class PatrolState : FSMState
  {
      //路徑點
      private List<Transform> path = new List<Transform>();
      private int index = 0;      //移動的開始索引
      private Transform playerTransform;
  
      public PatrolState(FSMSystem fsm) : base(fsm)
      {
          stateID = StateID.Patrol;
  
          //在這裏獲取一次，節省性能
          Transform pathTran = GameObject.Find("Path").transform;
          Transform[] children = pathTran.GetComponentsInChildren<Transform>();   //還包含父物體
          //剔除父物體
          foreach (Transform child in children)
          {
              if (child!= pathTran)
              {
                  path.Add(child);
              }
          }
  
          playerTransform = GameObject.Find("Player").transform;
  
      }
  
      //這個方法在FSMSystem中調用
      public override void Act(GameObject gameObject)
      {
          gameObject.transform.LookAt(path[index].position);
          gameObject.transform.Translate(Vector3.forward * Time.deltaTime * 3);
          if (Vector3.Distance(gameObject.transform.position,path[index].position)<1)     //自身位置與目標位置的距離
          {
              index++;
              index %= path.Count;    //index在數組內循環
          }
      }
  
      public override void Reason(GameObject gameObject)
      {
          //與主角距離小於3的時候開始追擊玩家
          if (Vector3.Distance(playerTransform.position,gameObject.transform.position)<3)
          {
              fsm.PerformTransition(Transition.SeePlayer);
          } 
      }
  }
  

• using System.Collections;
  using System.Collections.Generic;
  using UnityEngine;
  
  public class ChaseState : FSMState
  {
      private Transform playerTransform;
  
      public ChaseState(FSMSystem fsm) : base(fsm)
      {
          stateID = StateID.Chase;
          playerTransform = GameObject.Find("Player").transform;
      }
  
      public override void Act(GameObject gameObject)
      {
          gameObject.transform.LookAt(playerTransform.position);
          gameObject.transform.Translate(Vector3.forward * 2 * Time.deltaTime);
      }
  
      public override void Reason(GameObject gameObject)
      {
          //與主角距離大於6時,執行尋路狀態
          if (Vector3.Distance(playerTransform.position, gameObject.transform.position) > 6)
          {
              fsm.PerformTransition(Transition.LostPlayer);
          }
      }
  }
  

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