C#/基于Unity 行为树的实现步骤【纯代码】
16lz
2021-01-22
以下是纯代码参考， 没有Unity插件的节点编辑导出配置等内容。 行为树的概念， 各种 Unity 插件在这里都没有进行介绍。 代码是根据Unity的 2D Game Kit ，总结提炼的， 对于学习和理解行为树会很有帮助！
using BTAI;using UnityEngine;public class TestBT : MonoBehaviour, BTAI.IBTDebugable{ Root aiRoot = BT.Root(); private void OnEnable() { aiRoot.OpenBranch( BT.If(TestVisibleTarget).OpenBranch( BT.Call(Aim), BT.Call(Shoot) ), BT.Sequence().OpenBranch( BT.Call(Walk), BT.Wait(5.0f), BT.Call(Turn), BT.Wait(1.0f), BT.Call(Turn) ) ); } private void Turn() { Debug.Log("执行了 Turn"); } private void Walk() { Debug.Log("执行了 Walk"); } private void Shoot() { Debug.Log("执行了 Shoot"); } private void Aim() { Debug.Log("执行了 Aim"); } private bool TestVisibleTarget() { var isSuccess = UnityEngine.Random.Range(0, 2) == 1; Debug.Log("执行了 TestVisibleTarget Result:" + isSuccess); return isSuccess; } private void Update() { aiRoot.Tick(); } public Root GetAIRoot() { return aiRoot; }}
using System.Collections.Generic;using UnityEngine;/// <summary>/// 这只是脚本系统/// 行为树会从Root节点开始遍历子节点。Update中执行/// 每个节点都有相关的操作，但是基本上就是返回三种状态/// ● Success: 节点成功完成任务/// ● Failure: 节点未通过任务/// ● Continue:节点尚未完成任务。/// 但是每个节点的父节点对子节点的结果处理方式还不同。 例如/// ● Test 节点： 测试节点将调用其子节点并在测试为真时返回子节点状态，如果测试为假，则返回Failure而不调用其子节点。/// 行为树的一种构造方式如下：/// Root aiRoot = BT.Root(); /// aiRoot.Do( /// BT.If(TestVisibleTarget).Do(/// BT.Call(Aim),/// BT.Call(Shoot)/// ),/// BT.Sequence().Do(/// BT.Call(Walk),/// BT.Wait(5.0f),/// BT.Call(Turn),/// BT.Wait(1.0f),/// BT.Call(Turn)/// )/// ); ///然后在Update中 调用 aiRoot.Tick() 。 刚刚构造的行为树是怎么样的检查过程呢？ ///1、首先检查TestVisibleTarget是否返回Ture，如果是继续执行子节点执行Aim函数和Shoot函数///2、TestVisibleTarget是否返回false,if节点将返回Failure， 然后Root 将转向下一个子节点。这是个Sequence节点，它从执行第一个子节点开始。/// 1）将调用Walk函数，直接返回 Success，以便Sequence将下一个子节点激活并执行它。/// 2）执行Wait 节点，只是要等待5秒，还是第一次调用，所以肯定返回Running状态， 当Sequence从子节点上得到Running状态时，不会更改激活的子节点索引，下次Update的时候还是从这个节点开始执行///3、Update的执行，当Wait节点等待的时间到了的时候，将会返回Success， 以便序列将转到下一个孩子。///脚本中的Node列表 /// Sequence：//一个接一个地执行子节点。如果子节点返回：//●Success：Sequence将选择下一帧的下一个孩子开始。//●Failure：Sequence将返回到下一帧的第一个子节点（从头开始）。//●Continue：Sequence将在下一帧再次调用该节点。//RandomSequence：// 每次调用时，从子列表中执行一个随机子节点。您可以在构造函数中指定要应用于每个子项的权重列表作为int数组，以使某些子项更有可能被选中。//Selector ：//按顺序执行所有子项，直到一个返回Success，然后退出而不执行其余子节点。如果没有返回Success，则此节点将返回Failure。// Condition ：// 如果给定函数返回true，则此节点返回Success;如果为false，则返回Failure。// 与其他依赖于子节点结果的节点链接时很有用（例如，Sequence，Selector等）// If ：//调用给定的函数。// ●如果返回true，则调用当前活动的子级并返回其状态。// ●否则，它将在不调用其子项的情况下返回Failure// While：//只要给定函数返回true，就返回Continue（因此，下一帧将再次从该节点开始，而不会评估所有先前的节点）。//子节点们将陆续被执行。//当函数返回false并且循环中断时，将返回Failure。// Call //调用给定的函数，它将始终返回Success。是动作节点！//Repeat //将连续执行给定次数的所有子节点。//始终返回Continue，直到达到计数，并返回Success。//Wait//将返回Continue，直到达到给定时间（首次调用时开始），然后返回Success。//Trigger //允许在给定的动画师animator中设置Trigger参数（如果最后一个参数设置为false，则取消设置触发器）。始终返回成功。//SetBool//允许在给定的animator中设置布尔参数的值。始终返回成功//SetActive //设置给定GameObject的活动/非活动状态。始终返回成功。/// </summary>namespace BTAI{ public enum BTState { Failure, Success, Continue, Abort } /// <summary> /// 节点 对象工厂 /// </summary> public static class BT { public static Root Root() { return new Root(); } public static Sequence Sequence() { return new Sequence(); } public static Selector Selector(bool shuffle = false) { return new Selector(shuffle); } public static Action RunCoroutine(System.Func<IEnumerator<BTState>> coroutine) { return new Action(coroutine); } public static Action Call(System.Action fn) { return new Action(fn); } public static ConditionalBranch If(System.Func<bool> fn) { return new ConditionalBranch(fn); } public static While While(System.Func<bool> fn) { return new While(fn); } public static Condition Condition(System.Func<bool> fn) { return new Condition(fn); } public static Repeat Repeat(int count) { return new Repeat(count); } public static Wait Wait(float seconds) { return new Wait(seconds); } public static Trigger Trigger(Animator animator, string name, bool set = true) { return new Trigger(animator, name, set); } public static WaitForAnimatorState WaitForAnimatorState(Animator animator, string name, int layer = 0) { return new WaitForAnimatorState(animator, name, layer); } public static SetBool SetBool(Animator animator, string name, bool value) { return new SetBool(animator, name, value); } public static SetActive SetActive(GameObject gameObject, bool active) { return new SetActive(gameObject, active); } public static WaitForAnimatorSignal WaitForAnimatorSignal(Animator animator, string name, string state, int layer = 0) { return new WaitForAnimatorSignal(animator, name, state, layer); } public static Terminate Terminate() { return new Terminate(); } public static Log Log(string msg) { return new Log(msg); } public static RandomSequence RandomSequence(int[] weights = null) { return new BTAI.RandomSequence(weights); } } /// <summary> /// 节点抽象类 /// </summary> public abstract class BTNode { public abstract BTState Tick(); } /// <summary> /// 包含子节点的组合 节点基类 /// </summary> public abstract class Branch : BTNode { protected int activeChild; protected List<BTNode> children = new List<BTNode>(); public virtual Branch OpenBranch(params BTNode[] children) { for (var i = 0; i < children.Length; i++) this.children.Add(children[i]); return this; } public List<BTNode> Children() { return children; } public int ActiveChild() { return activeChild; } public virtual void ResetChildren() { activeChild = 0; for (var i = 0; i < children.Count; i++) { Branch b = children[i] as Branch; if (b != null) { b.ResetChildren(); } } } } /// <summary> /// 装饰节点 只包含一个子节点，用于某种方式改变这个节点的行为 /// 比如过滤器（用于决定是否允许子节点运行的，如：Until Success, Until Fail等），这种节点的子节点应该是条件节点，条件节点一直检测“视线中是否有敌人”，知道发现敌人为止。 /// 或者 Limit 节点，用于指定某个子节点的最大运行次数 /// 或者 Timer节点，设置了一个计时器，不会立即执行子节点，而是等一段时间，时间到了开始执行子节点 /// 或者 TimerLimit节点，用于指定某个子节点的最长运行时间。 /// 或者 用于产生某个返回状态， /// </summary> public abstract class Decorator : BTNode { protected BTNode child; public Decorator Do(BTNode child) { this.child = child; return this; } } /// <summary> /// 顺序节点 （从左到右依次执行所有子节点，只要子节点返回Success就继续执行后续子节点，直到遇到Failure或者Runing， /// 停止后续执行，并把这个节点返回给父节点，只有它的所有子节点都是Success他才会向父节点返回Success） /// </summary> public class Sequence : Branch { public override BTState Tick() { var childState = children[activeChild].Tick(); switch (childState) { case BTState.Success: activeChild++; if (activeChild == children.Count) { activeChild = 0; return BTState.Success; } else return BTState.Continue; case BTState.Failure: activeChild = 0; return BTState.Failure; case BTState.Continue: return BTState.Continue; case BTState.Abort: activeChild = 0; return BTState.Abort; } throw new System.Exception("This should never happen, but clearly it has."); } } /// <summary> /// 选择节点从左到右依次执行所有子节点 ，只要遇到failure就继续执行后续子节点，直到遇到一个节点返回Success或Running为止。向父节点返回Success或Running /// 所有子节点都是Fail， 那么向父节点凡湖Fail /// 选择节点 用来在可能的行为集合中选择第一个成功的。 比如一个试图躲避枪击的AI角色， 它可以通过寻找隐蔽点， 或离开危险区域， 或寻找援助等多种方式实现目标。 /// 利用选择节点，他会尝试寻找Cover，失败后在试图逃离危险区域。 /// </summary> public class Selector : Branch { public Selector(bool shuffle) { if (shuffle) { var n = children.Count; while (n > 1) { n--; var k = Mathf.FloorToInt(Random.value * (n + 1)); var value = children[k]; children[k] = children[n]; children[n] = value; } } } public override BTState Tick() { var childState = children[activeChild].Tick(); switch (childState) { case BTState.Success: activeChild = 0; return BTState.Success; case BTState.Failure: activeChild++; if (activeChild == children.Count) { activeChild = 0; return BTState.Failure; } else return BTState.Continue; case BTState.Continue: return BTState.Continue; case BTState.Abort: activeChild = 0; return BTState.Abort; } throw new System.Exception("This should never happen, but clearly it has."); } } /// <summary> /// 行为节点 调用方法，或运行协程。完成实际工作， 例如播放动画，让角色移动位置，感知敌人，更换武器，播放声音，增加生命值等。 /// </summary> public class Action : BTNode { System.Action fn; System.Func<IEnumerator<BTState>> coroutineFactory; IEnumerator<BTState> coroutine; public Action(System.Action fn) { this.fn = fn; } public Action(System.Func<IEnumerator<BTState>> coroutineFactory) { this.coroutineFactory = coroutineFactory; } public override BTState Tick() { if (fn != null) { fn(); return BTState.Success; } else { if (coroutine == null) coroutine = coroutineFactory(); if (!coroutine.MoveNext()) { coroutine = null; return BTState.Success; } var result = coroutine.Current; if (result == BTState.Continue) return BTState.Continue; else { coroutine = null; return result; } } } public override string ToString() { return "Action : " + fn.Method.ToString(); } } /// <summary> /// 条件节点 调用方法，如果方法返回true则返回成功，否则返回失败。 /// 用来测试当前是否满足某些性质或条件，例如“玩家是否在20米之内？”“是否能看到玩家？”“生命值是否大于50？”“弹药是否足够？”等 /// </summary> public class Condition : BTNode { public System.Func<bool> fn; public Condition(System.Func<bool> fn) { this.fn = fn; } public override BTState Tick() { return fn() ? BTState.Success : BTState.Failure; } public override string ToString() { return "Condition : " + fn.Method.ToString(); } } /// <summary> /// 当方法为True的时候 尝试执行当前 子节点 /// </summary> public class ConditionalBranch : Block { public System.Func<bool> fn; bool tested = false; public ConditionalBranch(System.Func<bool> fn) { this.fn = fn; } public override BTState Tick() { if (!tested) { tested = fn(); } if (tested) { // 当前子节点执行完就进入下一个节点(超上限就返回到第一个) var result = base.Tick(); // 没执行完 if (result == BTState.Continue) return BTState.Continue; else { tested = false; // 最后一个子节点执行完，才会为Ture return result; } } else { return BTState.Failure; } } public override string ToString() { return "ConditionalBranch : " + fn.Method.ToString(); } } /// <summary> /// While节点 只要方法 返回True 就执行所有子节点， 否则返回 Failure /// </summary> public class While : Block { public System.Func<bool> fn; public While(System.Func<bool> fn) { this.fn = fn; } public override BTState Tick() { if (fn()) base.Tick(); else { //if we exit the loop ResetChildren(); return BTState.Failure; } return BTState.Continue; } public override string ToString() { return "While : " + fn.Method.ToString(); } } /// <summary> /// 阻塞节点 如果当前子节点是Continue 说明没有执行完，阻塞着，执行完之后在继续它后面的兄弟节点 不管成功失败。 /// 如果当前结点是最后一个节点并执行完毕，说明成功！否则就是处于Continue状态。 /// 几个基本上是抽象节点， 像是让所有子节点都执行一遍， 当前子节点执行完就进入下一个节点(超上限就返回到第一个) /// </summary> public abstract class Block : Branch { public override BTState Tick() { switch (children[activeChild].Tick()) { case BTState.Continue: return BTState.Continue; default: activeChild++; if (activeChild == children.Count) { activeChild = 0; return BTState.Success; } return BTState.Continue; } } } public class Root : Block { public bool isTerminated = false; public override BTState Tick() { if (isTerminated) return BTState.Abort; while (true) { switch (children[activeChild].Tick()) { case BTState.Continue: return BTState.Continue; case BTState.Abort: isTerminated = true; return BTState.Abort; default: activeChild++; if (activeChild == children.Count) { activeChild = 0; return BTState.Success; } continue; } } } } /// <summary> /// 多次运行子节点（一个子节点执行一次就算一次） /// </summary> public class Repeat : Block { public int count = 1; int currentCount = 0; public Repeat(int count) { this.count = count; } public override BTState Tick() { if (count > 0 && currentCount < count) { var result = base.Tick(); switch (result) { case BTState.Continue: return BTState.Continue; default: currentCount++; if (currentCount == count) { currentCount = 0; return BTState.Success; } return BTState.Continue; } } return BTState.Success; } public override string ToString() { return "Repeat Until : " + currentCount + " / " + count; } } /// <summary> /// 随机的顺序 执行子节点 /// </summary> public class RandomSequence : Block { int[] m_Weight = null; int[] m_AddedWeight = null; /// <summary> /// 每次再次触发时，将选择一个随机子节点 /// </summary> /// <param name="weight">保留null，以便所有子节点具有相同的权重。 /// 如果权重低于子节点， 则后续子节点的权重都为1</param> public RandomSequence(int[] weight = null) { activeChild = -1; m_Weight = weight; } public override Branch OpenBranch(params BTNode[] children) { m_AddedWeight = new int[children.Length]; for (int i = 0; i < children.Length; ++i) { int weight = 0; int previousWeight = 0; if (m_Weight == null || m_Weight.Length <= i) {//如果没有那个权重， 就将权重 设置为1 weight = 1; } else weight = m_Weight[i]; if (i > 0) previousWeight = m_AddedWeight[i - 1]; m_AddedWeight[i] = weight + previousWeight; } return base.OpenBranch(children); } public override BTState Tick() { if (activeChild == -1) PickNewChild(); var result = children[activeChild].Tick(); switch (result) { case BTState.Continue: return BTState.Continue; default: PickNewChild(); return result; } } void PickNewChild() { int choice = Random.Range(0, m_AddedWeight[m_AddedWeight.Length - 1]); for (int i = 0; i < m_AddedWeight.Length; ++i) { if (choice - m_AddedWeight[i] <= 0) { activeChild = i; break; } } } public override string ToString() { return "Random Sequence : " + activeChild + "/" + children.Count; } } /// <summary> /// 暂停执行几秒钟。 /// </summary> public class Wait : BTNode { public float seconds = 0; float future = -1; public Wait(float seconds) { this.seconds = seconds; } public override BTState Tick() { if (future < 0) future = Time.time + seconds; if (Time.time >= future) { future = -1; return BTState.Success; } else return BTState.Continue; } public override string ToString() { return "Wait : " + (future - Time.time) + " / " + seconds; } } /// <summary> /// 设置动画 trigger 参数 /// </summary> public class Trigger : BTNode { Animator animator; int id; string triggerName; bool set = true; //如果 set == false, 则重置trigger而不是设置它。 public Trigger(Animator animator, string name, bool set = true) { this.id = Animator.StringToHash(name); this.animator = animator; this.triggerName = name; this.set = set; } public override BTState Tick() { if (set) animator.SetTrigger(id); else animator.ResetTrigger(id); return BTState.Success; } public override string ToString() { return "Trigger : " + triggerName; } } /// <summary> /// 设置动画 boolean 参数 /// </summary> public class SetBool : BTNode { Animator animator; int id; bool value; string triggerName; public SetBool(Animator animator, string name, bool value) { this.id = Animator.StringToHash(name); this.animator = animator; this.value = value; this.triggerName = name; } public override BTState Tick() { animator.SetBool(id, value); return BTState.Success; } public override string ToString() { return "SetBool : " + triggerName + " = " + value.ToString(); } } /// <summary> /// 等待animator达到一个状态。 /// </summary> public class WaitForAnimatorState : BTNode { Animator animator; int id; int layer; string stateName; public WaitForAnimatorState(Animator animator, string name, int layer = 0) { this.id = Animator.StringToHash(name); if (!animator.HasState(layer, this.id)) { Debug.LogError("The animator does not have state: " + name); } this.animator = animator; this.layer = layer; this.stateName = name; } public override BTState Tick() { var state = animator.GetCurrentAnimatorStateInfo(layer); if (state.fullPathHash == this.id || state.shortNameHash == this.id) return BTState.Success; return BTState.Continue; } public override string ToString() { return "Wait For State : " + stateName; } } /// <summary> /// 设置 GameObject 的激活状态 /// </summary> public class SetActive : BTNode { GameObject gameObject; bool active; public SetActive(GameObject gameObject, bool active) { this.gameObject = gameObject; this.active = active; } public override BTState Tick() { gameObject.SetActive(this.active); return BTState.Success; } public override string ToString() { return "Set Active : " + gameObject.name + " = " + active; } } /// <summary> /// 等待animator从SendSignal状态机行为 接收信号。 SendSignal : StateMachineBehaviour /// </summary> public class WaitForAnimatorSignal : BTNode { // 进入或退出动画都为 False， 只有执行中为True internal bool isSet = false; string name; int id; public WaitForAnimatorSignal(Animator animator, string name, string state, int layer = 0) { this.name = name; this.id = Animator.StringToHash(name); if (!animator.HasState(layer, this.id)) { Debug.LogError("The animator does not have state: " + name); } else { SendSignal.Register(animator, name, this); } } public override BTState Tick() { if (!isSet) return BTState.Continue; else { isSet = false; return BTState.Success; } } public override string ToString() { return "Wait For Animator Signal : " + name; } } /// <summary> /// 终止节点 切换到中止 状态 /// </summary> public class Terminate : BTNode { public override BTState Tick() { return BTState.Abort; } } /// <summary> /// Log 输出Log 的节点 /// </summary> public class Log : BTNode { string msg; public Log(string msg) { this.msg = msg; } public override BTState Tick() { Debug.Log(msg); return BTState.Success; } }}#if UNITY_EDITORnamespace BTAI{ public interface IBTDebugable { Root GetAIRoot(); }}#endifusing BTAI;using System.Collections.Generic;using UnityEditor;using UnityEngine;namespace Gamekit2D{ /// <summary> /// 运行是查看 行为树中所有节点的状态 /// </summary> public class BTDebug : EditorWindow { protected BTAI.Root _currentRoot = null; [MenuItem("Kit Tools/Behaviour Tree Debug")] static void OpenWindow() { BTDebug btdebug = GetWindow<BTDebug>(); btdebug.Show(); } private void OnGUI() { if (!Application.isPlaying) { EditorGUILayout.HelpBox("Only work during play mode.", MessageType.Info); } else { if (_currentRoot == null) FindRoot(); else { RecursiveTreeParsing(_currentRoot, 0, true); } } } void Update() { Repaint(); } void RecursiveTreeParsing(Branch branch, int indent, bool parentIsActive) { List<BTNode> nodes = branch.Children(); for (int i = 0; i < nodes.Count; ++i) { EditorGUI.indentLevel = indent; bool isActiveChild = branch.ActiveChild() == i; GUI.color = (isActiveChild && parentIsActive) ? Color.green : Color.white; EditorGUILayout.LabelField(nodes[i].ToString()); if (nodes[i] is Branch) RecursiveTreeParsing(nodes[i] as Branch, indent + 1, isActiveChild); } } void FindRoot() { if (Selection.activeGameObject == null) { _currentRoot = null; return; } IBTDebugable debugable = Selection.activeGameObject.GetComponentInChildren<IBTDebugable>(); if (debugable != null) { _currentRoot = debugable.GetAIRoot(); } } }}就是在菜单“Kit Tools/Behaviour Tree Debug" 可以查看TestBT.cs 对象所在行为树
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