596 lines
15 KiB
Markdown
596 lines
15 KiB
Markdown
# 高级用法
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本文介绍行为树系统的高级功能和使用技巧。
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## 子树系统
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子树允许你将行为树的一部分抽取为独立的资产，实现复用和模块化。
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### 创建子树
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子树本质上就是一个独立的行为树资产：
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```typescript
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import { BehaviorTreeBuilder, BlackboardValueType, TaskStatus } from '@esengine/behavior-tree';
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// 创建一个巡逻子树
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const patrolSubtree = BehaviorTreeBuilder.create(scene, 'PatrolBehavior')
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.blackboard()
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.defineVariable('patrolPoints', BlackboardValueType.Array, [])
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.defineVariable('currentIndex', BlackboardValueType.Number, 0)
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.endBlackboard()
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.sequence('PatrolSequence')
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.action('MoveToNextPoint', (entity, blackboard) => {
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const points = blackboard?.getValue('patrolPoints') || [];
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const index = blackboard?.getValue('currentIndex') || 0;
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if (points.length === 0) return TaskStatus.Failure;
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const target = points[index];
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console.log(`移动到巡逻点 ${index}:`, target);
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// 移动逻辑...
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return TaskStatus.Success;
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})
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.action('UpdateIndex', (entity, blackboard) => {
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const points = blackboard?.getValue('patrolPoints') || [];
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const index = blackboard?.getValue('currentIndex') || 0;
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const nextIndex = (index + 1) % points.length;
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blackboard?.setValue('currentIndex', nextIndex);
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return TaskStatus.Success;
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})
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.wait(1.0)
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.end()
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.build();
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```
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### 使用SubTree节点
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在主树中引用子树：
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```typescript
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const mainTree = BehaviorTreeBuilder.create(scene, 'EnemyAI')
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.blackboard()
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.defineVariable('health', BlackboardValueType.Number, 100)
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.endBlackboard()
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.selector('Root')
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.sequence('Combat')
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.compareBlackboardValue('health', CompareOperator.Greater, 50)
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.action('Attack', () => TaskStatus.Success)
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.end()
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// 使用子树
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.subTree(patrolSubtree, {
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inheritParentBlackboard: true, // 继承父黑板
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propagateFailure: true // 传播失败状态
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})
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.end()
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.build();
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```
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### 从资产加载子树
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使用编辑器创建的子树资产：
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```typescript
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import {
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BehaviorTreeAssetSerializer,
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BehaviorTreeAssetLoader,
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BehaviorTreeBuilder
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} from '@esengine/behavior-tree';
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// 加载子树资产
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const subtreeJson = await loadFile('patrol-behavior.btree.json');
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const subtreeAsset = BehaviorTreeAssetSerializer.deserialize(subtreeJson);
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// 在主树中使用
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const mainTree = BehaviorTreeBuilder.create(scene, 'MainAI')
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.selector('Root')
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.subTreeFromAsset(subtreeAsset, scene, {
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namePrefix: 'Patrol',
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inheritParentBlackboard: true
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})
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.end()
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.build();
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```
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### 子树黑板继承
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当启用 `inheritParentBlackboard` 时，子树可以访问父树的黑板变量：
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```typescript
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// 父树定义的变量
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const parent = BehaviorTreeBuilder.create(scene, 'Parent')
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.blackboard()
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.defineVariable('playerPosition', BlackboardValueType.Vector3, { x: 0, y: 0, z: 0 })
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.endBlackboard()
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.subTree(childTree, { inheritParentBlackboard: true })
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.build();
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// 子树可以访问父树的 playerPosition 变量
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const child = BehaviorTreeBuilder.create(scene, 'Child')
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.action('UseParentData', (entity, blackboard) => {
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const playerPos = blackboard?.getValue('playerPosition');
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console.log('玩家位置:', playerPos);
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return TaskStatus.Success;
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})
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.build();
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```
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## 异步操作
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### 异步动作
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对于需要多帧完成的操作，返回 `TaskStatus.Running`：
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```typescript
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.action('LoadResource', (entity, blackboard, deltaTime) => {
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// 检查是否已开始加载
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let loadingState = blackboard?.getValue('loadingState');
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if (!loadingState) {
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// 第一次执行，开始加载
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startAsyncLoad().then(result => {
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blackboard?.setValue('loadingState', 'completed');
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blackboard?.setValue('loadedData', result);
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});
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blackboard?.setValue('loadingState', 'loading');
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return TaskStatus.Running; // 继续等待
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}
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if (loadingState === 'loading') {
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return TaskStatus.Running; // 仍在加载中
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}
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if (loadingState === 'completed') {
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// 加载完成
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blackboard?.setValue('loadingState', null);
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return TaskStatus.Success;
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}
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return TaskStatus.Failure;
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})
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```
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### 超时控制
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使用装饰器实现超时：
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```typescript
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.timeout(5.0, 'LoadTimeout') // 5秒超时
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.action('SlowOperation', () => {
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// 长时间运行的操作
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return TaskStatus.Running;
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})
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.end()
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```
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## 全局黑板
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全局黑板在所有行为树实例之间共享数据。
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### 创建全局黑板
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```typescript
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import { GlobalBlackboard } from '@esengine/behavior-tree';
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// 设置全局变量
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GlobalBlackboard.setValue('gameState', 'playing');
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GlobalBlackboard.setValue('playerCount', 4);
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GlobalBlackboard.setValue('difficulty', 'hard');
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```
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### 在行为树中访问全局黑板
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```typescript
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.action('CheckGameState', (entity, blackboard) => {
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const gameState = GlobalBlackboard.getValue('gameState');
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if (gameState === 'paused') {
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return TaskStatus.Failure;
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}
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return TaskStatus.Success;
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})
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```
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### 全局黑板监听
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监听全局变量变化：
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```typescript
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const unsubscribe = GlobalBlackboard.subscribe('difficulty', (newValue, oldValue) => {
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console.log(`难度从 ${oldValue} 变为 ${newValue}`);
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// 调整AI行为
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});
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// 取消监听
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unsubscribe();
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```
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## 性能优化
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### 1. 使用对象池
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复用行为树实体以减少GC压力：
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```typescript
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class BehaviorTreePool {
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private pool: Map<string, Entity[]> = new Map();
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private scene: Scene;
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constructor(scene: Scene) {
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this.scene = scene;
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}
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acquire(asset: BehaviorTreeAsset, poolKey: string): Entity {
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let pool = this.pool.get(poolKey);
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if (!pool) {
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pool = [];
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this.pool.set(poolKey, pool);
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}
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if (pool.length > 0) {
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const entity = pool.pop()!;
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BehaviorTreeStarter.restart(entity);
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return entity;
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}
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return BehaviorTreeAssetLoader.instantiate(asset, this.scene);
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}
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release(entity: Entity, poolKey: string) {
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BehaviorTreeStarter.stop(entity);
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const pool = this.pool.get(poolKey) || [];
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pool.push(entity);
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this.pool.set(poolKey, pool);
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}
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clear() {
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for (const [key, pool] of this.pool) {
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for (const entity of pool) {
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entity.destroy();
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}
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}
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this.pool.clear();
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}
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}
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// 使用示例
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const pool = new BehaviorTreePool(scene);
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// 获取AI实例
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const enemyAI = pool.acquire(enemyAsset, 'enemy');
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// 释放回池
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pool.release(enemyAI, 'enemy');
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```
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### 2. 降低更新频率
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对于不需要每帧更新的AI，可以在行为树内部使用节流逻辑：
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```typescript
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// 方法1: 在行为树根节点使用Cooldown装饰器
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const ai = BehaviorTreeBuilder.create(scene, 'ThrottledAI')
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.cooldown(0.1) // 每0.1秒执行一次
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.selector()
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// AI逻辑
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.end()
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.end()
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.build();
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// 方法2: 在Action中实现自定义节流
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.action('ThrottledAction', (entity, blackboard, deltaTime) => {
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const lastUpdate = blackboard?.getValue('lastUpdateTime') || 0;
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const currentTime = Date.now();
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const updateInterval = 100; // 100ms
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if (currentTime - lastUpdate < updateInterval) {
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return TaskStatus.Running;
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}
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blackboard?.setValue('lastUpdateTime', currentTime);
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// 执行实际逻辑
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performAILogic();
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return TaskStatus.Success;
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})
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```
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### 3. 条件缓存
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缓存昂贵的条件检查结果：
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```typescript
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.action('CacheExpensiveCheck', (entity, blackboard) => {
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const cacheKey = 'expensiveCheckResult';
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const cacheTime = blackboard?.getValue('expensiveCheckTime') || 0;
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const currentTime = Date.now();
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// 如果缓存未过期（1秒内），直接使用缓存结果
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if (currentTime - cacheTime < 1000) {
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const cachedResult = blackboard?.getValue(cacheKey);
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return cachedResult ? TaskStatus.Success : TaskStatus.Failure;
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}
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// 执行昂贵的检查
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const result = performExpensiveCheck();
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// 缓存结果
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blackboard?.setValue(cacheKey, result);
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blackboard?.setValue('expensiveCheckTime', currentTime);
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return result ? TaskStatus.Success : TaskStatus.Failure;
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})
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```
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### 4. 分帧执行
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将大量计算分散到多帧：
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```typescript
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.action('ProcessLargeDataset', (entity, blackboard, deltaTime) => {
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const data = blackboard?.getValue('dataset') || [];
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let processedIndex = blackboard?.getValue('processedIndex') || 0;
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const batchSize = 100; // 每帧处理100个
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const endIndex = Math.min(processedIndex + batchSize, data.length);
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for (let i = processedIndex; i < endIndex; i++) {
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// 处理单个数据项
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processItem(data[i]);
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}
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blackboard?.setValue('processedIndex', endIndex);
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if (endIndex >= data.length) {
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// 全部处理完成
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blackboard?.setValue('processedIndex', 0);
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return TaskStatus.Success;
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}
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return TaskStatus.Running; // 继续下一帧
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})
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```
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## 序列化和反序列化
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### JSON格式
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标准的可读格式：
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```typescript
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import { BehaviorTreeAssetSerializer } from '@esengine/behavior-tree';
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// 序列化为JSON
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const asset = createBehaviorTreeAsset();
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const json = BehaviorTreeAssetSerializer.serialize(asset);
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// 保存到文件
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await saveFile('ai-behavior.btree.json', json);
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// 从JSON加载
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const loadedJson = await loadFile('ai-behavior.btree.json');
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const loadedAsset = BehaviorTreeAssetSerializer.deserialize(loadedJson);
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```
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### 二进制格式
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体积更小的二进制格式（通常比JSON小60-70%）：
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```typescript
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// 序列化为二进制
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const binary = BehaviorTreeAssetSerializer.serializeToBinary(asset);
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// 保存二进制文件
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await saveFile('ai-behavior.btree.bin', binary);
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// 从二进制加载
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const loadedBinary = await loadFile('ai-behavior.btree.bin');
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const loadedAsset = BehaviorTreeAssetSerializer.deserializeFromBinary(loadedBinary);
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```
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### 格式转换
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在JSON和二进制之间转换：
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```typescript
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// JSON转二进制
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const jsonData = await loadFile('tree.btree.json');
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const asset = BehaviorTreeAssetSerializer.deserialize(jsonData);
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const binary = BehaviorTreeAssetSerializer.serializeToBinary(asset);
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await saveFile('tree.btree.bin', binary);
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// 二进制转JSON
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const binaryData = await loadFile('tree.btree.bin');
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const asset2 = BehaviorTreeAssetSerializer.deserializeFromBinary(binaryData);
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const json = BehaviorTreeAssetSerializer.serialize(asset2);
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await saveFile('tree.btree.json', json);
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```
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## 调试技巧
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### 1. 日志节点
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在关键位置添加日志：
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```typescript
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.log('开始战斗序列', 'info')
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.sequence('Combat')
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.log('检查生命值', 'debug')
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.compareBlackboardValue('health', CompareOperator.Greater, 0)
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.log('执行攻击', 'info')
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.action('Attack', () => TaskStatus.Success)
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.end()
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```
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### 2. 黑板快照
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定期输出黑板状态：
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```typescript
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.action('DebugBlackboard', (entity, blackboard) => {
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console.log('=== 黑板快照 ===');
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const vars = blackboard?.getAllVariables();
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for (const [key, value] of Object.entries(vars || {})) {
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console.log(`${key}:`, value);
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}
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return TaskStatus.Success;
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})
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```
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### 3. 条件断言
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验证重要条件：
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```typescript
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.action('AssertPlayerExists', (entity, blackboard) => {
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const player = blackboard?.getValue('player');
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if (!player) {
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console.error('断言失败: 玩家不存在');
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return TaskStatus.Failure;
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}
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return TaskStatus.Success;
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})
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```
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### 4. 性能分析
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测量节点执行时间：
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```typescript
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.action('ProfiledAction', (entity, blackboard) => {
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const startTime = performance.now();
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// 执行操作
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doSomething();
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const elapsed = performance.now() - startTime;
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console.log(`操作耗时: ${elapsed.toFixed(2)}ms`);
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return TaskStatus.Success;
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})
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```
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### 5. 可视化调试
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在编辑器中运行行为树并观察节点状态：
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```typescript
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import { BehaviorTreeDebugger } from '@esengine/behavior-tree';
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// 启用调试模式
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BehaviorTreeDebugger.enable(aiEntity);
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// 获取当前执行路径
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const executionPath = BehaviorTreeDebugger.getExecutionPath(aiEntity);
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console.log('执行路径:', executionPath);
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// 获取节点状态
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const nodeStatus = BehaviorTreeDebugger.getNodeStatus(aiEntity, nodeId);
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console.log('节点状态:', nodeStatus);
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```
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## 常见模式
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### 1. 状态机模式
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使用行为树实现状态机：
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```typescript
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const fsm = BehaviorTreeBuilder.create(scene, 'StateMachine')
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.blackboard()
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.defineVariable('currentState', BlackboardValueType.String, 'idle')
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.endBlackboard()
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.selector('StateSwitch')
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// Idle状态
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.sequence('IdleState')
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.checkBlackboardValue('currentState', 'idle')
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.action('IdleBehavior', (e, bb) => {
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console.log('执行Idle行为');
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// 状态转换条件
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if (shouldTransitionToMove()) {
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bb?.setValue('currentState', 'move');
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}
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return TaskStatus.Success;
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})
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.end()
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// Move状态
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.sequence('MoveState')
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.checkBlackboardValue('currentState', 'move')
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.action('MoveBehavior', (e, bb) => {
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console.log('执行Move行为');
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if (shouldTransitionToAttack()) {
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bb?.setValue('currentState', 'attack');
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}
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return TaskStatus.Success;
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})
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.end()
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// Attack状态
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.sequence('AttackState')
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.checkBlackboardValue('currentState', 'attack')
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.action('AttackBehavior', (e, bb) => {
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console.log('执行Attack行为');
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if (shouldTransitionToIdle()) {
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bb?.setValue('currentState', 'idle');
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}
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return TaskStatus.Success;
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})
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.end()
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.end()
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.build();
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```
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### 2. 优先级队列模式
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按优先级执行任务：
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```typescript
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.selector('PriorityQueue')
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// 最高优先级：生存
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.sequence('Survive')
|
||
.compareBlackboardValue('health', CompareOperator.Less, 20)
|
||
.action('Heal', () => TaskStatus.Success)
|
||
.end()
|
||
// 中优先级：战斗
|
||
.sequence('Combat')
|
||
.checkBlackboardExists('nearbyEnemy', true)
|
||
.action('Fight', () => TaskStatus.Success)
|
||
.end()
|
||
// 低优先级：收集资源
|
||
.sequence('Gather')
|
||
.action('CollectResources', () => TaskStatus.Success)
|
||
.end()
|
||
.end()
|
||
```
|
||
|
||
### 3. 并行任务模式
|
||
|
||
同时执行多个任务：
|
||
|
||
```typescript
|
||
.parallel(ParallelPolicy.RequireAll) // 所有任务都要成功
|
||
.action('PlayAnimation', () => TaskStatus.Success)
|
||
.action('PlaySound', () => TaskStatus.Success)
|
||
.action('SpawnParticles', () => TaskStatus.Success)
|
||
.end()
|
||
```
|
||
|
||
|
||
## 下一步
|
||
|
||
- 查看[自定义动作](./custom-actions.md)学习如何创建自定义行为节点
|
||
- 阅读[最佳实践](./best-practices.md)了解行为树设计技巧
|