507 lines
13 KiB
Markdown
507 lines
13 KiB
Markdown
# 资产管理
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本文介绍如何加载、管理和复用行为树资产。
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## 为什么需要资产管理？
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在实际游戏开发中，你可能会遇到以下场景：
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1. **多个实体共享同一个行为树** - 100个敌人使用同一套AI逻辑
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2. **动态加载行为树** - 从JSON文件加载行为树配置
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3. **子树复用** - 将常用的行为片段（如"巡逻"、"追击"）做成独立的子树
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4. **运行时切换行为树** - 敌人在不同阶段使用不同的行为树
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## BehaviorTreeAssetManager
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框架提供了 `BehaviorTreeAssetManager` 服务来统一管理行为树资产。
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### 核心概念
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- **BehaviorTreeData（行为树数据）**：行为树的定义，可以被多个实体共享
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- **BehaviorTreeRuntimeComponent（运行时组件）**：每个实体独立的运行时状态
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- **AssetManager（资产管理器）**：统一管理所有 BehaviorTreeData
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### 基本使用
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```typescript
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import { Core } from '@esengine/esengine';
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import {
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BehaviorTreeAssetManager,
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BehaviorTreeBuilder,
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BehaviorTreeStarter
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} from '@esengine/behavior-tree';
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// 1. 获取资产管理器（插件已自动注册）
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const assetManager = Core.services.resolve(BehaviorTreeAssetManager);
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// 2. 创建并注册行为树资产
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const enemyAI = BehaviorTreeBuilder.create('EnemyAI')
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.defineBlackboardVariable('health', 100)
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.selector('MainBehavior')
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.log('攻击')
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.end()
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.build();
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assetManager.loadAsset(enemyAI);
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// 3. 为多个实体使用同一份资产
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const enemy1 = scene.createEntity('Enemy1');
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const enemy2 = scene.createEntity('Enemy2');
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const enemy3 = scene.createEntity('Enemy3');
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// 获取共享的资产
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const sharedTree = assetManager.getAsset('EnemyAI');
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if (sharedTree) {
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BehaviorTreeStarter.start(enemy1, sharedTree);
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BehaviorTreeStarter.start(enemy2, sharedTree);
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BehaviorTreeStarter.start(enemy3, sharedTree);
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}
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```
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### 资产管理器 API
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```typescript
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// 加载资产
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assetManager.loadAsset(treeData);
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// 获取资产
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const tree = assetManager.getAsset('TreeID');
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// 检查资产是否存在
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if (assetManager.hasAsset('TreeID')) {
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// ...
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}
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// 卸载资产
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assetManager.unloadAsset('TreeID');
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// 获取所有资产ID
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const allIds = assetManager.getAllAssetIds();
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// 清空所有资产
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assetManager.clearAll();
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```
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## 从文件加载行为树
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### JSON 格式
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行为树可以导出为 JSON 格式：
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```json
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{
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"version": "1.0.0",
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"metadata": {
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"name": "EnemyAI",
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"description": "敌人AI行为树"
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},
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"rootNodeId": "root-1",
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"nodes": [
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{
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"id": "root-1",
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"name": "RootSelector",
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"nodeType": "Composite",
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"data": {
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"compositeType": "Selector"
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},
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"children": ["combat-1", "patrol-1"]
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},
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{
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"id": "combat-1",
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"name": "Combat",
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"nodeType": "Action",
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"data": {
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"actionType": "LogAction",
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"message": "攻击敌人"
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},
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"children": []
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}
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],
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"blackboard": [
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{
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"name": "health",
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"type": "number",
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"defaultValue": 100
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}
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]
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}
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```
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### 加载 JSON 文件
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```typescript
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import {
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BehaviorTreeAssetSerializer,
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BehaviorTreeAssetManager
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} from '@esengine/behavior-tree';
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async function loadTreeFromFile(filePath: string) {
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const assetManager = Core.services.resolve(BehaviorTreeAssetManager);
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// 1. 读取文件内容
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const jsonContent = await fetch(filePath).then(res => res.text());
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// 2. 反序列化
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const treeData = BehaviorTreeAssetSerializer.deserialize(jsonContent);
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// 3. 加载到资产管理器
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assetManager.loadAsset(treeData);
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return treeData;
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}
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// 使用
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const tree = await loadTreeFromFile('/assets/enemy-ai.btree.json');
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BehaviorTreeStarter.start(entity, tree);
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```
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## 子树（SubTree）
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子树允许你将常用的行为片段做成独立的树，然后在其他树中引用。
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### 为什么使用子树？
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1. **代码复用** - 避免重复定义相同的行为
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2. **模块化** - 将复杂的行为树拆分成小的可管理单元
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3. **团队协作** - 不同成员可以独立开发不同的子树
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### 创建子树
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```typescript
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// 1. 创建巡逻子树
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const patrolTree = BehaviorTreeBuilder.create('PatrolBehavior')
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.sequence('Patrol')
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.log('选择巡逻点', 'PickWaypoint')
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.log('移动到巡逻点', 'MoveToWaypoint')
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.wait(2.0, 'WaitAtWaypoint')
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.end()
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.build();
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// 2. 创建追击子树
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const chaseTree = BehaviorTreeBuilder.create('ChaseBehavior')
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.sequence('Chase')
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.log('锁定目标', 'LockTarget')
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.log('追击目标', 'ChaseTarget')
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.end()
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.build();
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// 3. 注册子树到资产管理器
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const assetManager = Core.services.resolve(BehaviorTreeAssetManager);
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assetManager.loadAsset(patrolTree);
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assetManager.loadAsset(chaseTree);
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```
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### 使用子树
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```typescript
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// 在主行为树中使用子树
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const mainTree = BehaviorTreeBuilder.create('EnemyAI')
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.defineBlackboardVariable('hasTarget', false)
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.selector('MainBehavior')
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// 条件：发现目标时执行追击子树
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.sequence('CombatBranch')
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.blackboardExists('hasTarget')
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.subTree('ChaseBehavior', { shareBlackboard: true })
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.end()
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// 默认：执行巡逻子树
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.subTree('PatrolBehavior', { shareBlackboard: true })
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.end()
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.build();
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assetManager.loadAsset(mainTree);
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// 启动主行为树
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const enemy = scene.createEntity('Enemy');
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BehaviorTreeStarter.start(enemy, mainTree);
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```
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### SubTree 配置选项
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```typescript
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.subTree('SubTreeID', {
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shareBlackboard: true, // 是否共享黑板（默认true）
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})
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```
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- **shareBlackboard: true** - 子树和父树共享黑板变量
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- **shareBlackboard: false** - 子树使用独立的黑板
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## 资源预加载
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在游戏启动时预加载所有行为树资产：
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```typescript
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class BehaviorTreePreloader {
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private assetManager: BehaviorTreeAssetManager;
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constructor() {
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this.assetManager = Core.services.resolve(BehaviorTreeAssetManager);
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}
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async preloadAll() {
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// 定义所有行为树文件
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const treeFiles = [
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'/assets/ai/enemy-ai.btree.json',
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'/assets/ai/boss-ai.btree.json',
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'/assets/ai/patrol.btree.json',
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'/assets/ai/chase.btree.json'
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];
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// 并行加载所有文件
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const loadPromises = treeFiles.map(file => this.loadTree(file));
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await Promise.all(loadPromises);
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console.log(`已加载 ${this.assetManager.getAssetCount()} 个行为树资产`);
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}
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private async loadTree(filePath: string) {
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const jsonContent = await fetch(filePath).then(res => res.text());
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const treeData = BehaviorTreeAssetSerializer.deserialize(jsonContent);
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this.assetManager.loadAsset(treeData);
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}
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}
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// 游戏启动时调用
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const preloader = new BehaviorTreePreloader();
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await preloader.preloadAll();
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```
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## 运行时切换行为树
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敌人在不同阶段使用不同的行为树：
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```typescript
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class EnemyAI {
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private entity: Entity;
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private assetManager: BehaviorTreeAssetManager;
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constructor(entity: Entity) {
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this.entity = entity;
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this.assetManager = Core.services.resolve(BehaviorTreeAssetManager);
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}
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// 切换到巡逻AI
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switchToPatrol() {
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const tree = this.assetManager.getAsset('PatrolAI');
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if (tree) {
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BehaviorTreeStarter.stop(this.entity);
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BehaviorTreeStarter.start(this.entity, tree);
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}
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}
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// 切换到战斗AI
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switchToCombat() {
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const tree = this.assetManager.getAsset('CombatAI');
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if (tree) {
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BehaviorTreeStarter.stop(this.entity);
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BehaviorTreeStarter.start(this.entity, tree);
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}
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}
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// 切换到狂暴模式
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switchToBerserk() {
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const tree = this.assetManager.getAsset('BerserkAI');
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if (tree) {
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BehaviorTreeStarter.stop(this.entity);
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BehaviorTreeStarter.start(this.entity, tree);
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}
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}
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}
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// 使用
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const enemyAI = new EnemyAI(enemyEntity);
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// Boss血量低于30%时进入狂暴
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const runtime = enemyEntity.getComponent(BehaviorTreeRuntimeComponent);
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const health = runtime?.getBlackboardValue<number>('health');
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if (health && health < 30) {
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enemyAI.switchToBerserk();
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}
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```
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## 内存优化
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### 1. 共享行为树数据
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```typescript
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// 好的做法：100个敌人共享1份BehaviorTreeData
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const sharedTree = assetManager.getAsset('EnemyAI');
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for (let i = 0; i < 100; i++) {
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const enemy = scene.createEntity(`Enemy${i}`);
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BehaviorTreeStarter.start(enemy, sharedTree!); // 共享数据
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}
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// 不好的做法：每个敌人创建独立的BehaviorTreeData
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for (let i = 0; i < 100; i++) {
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const enemy = scene.createEntity(`Enemy${i}`);
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const tree = BehaviorTreeBuilder.create('EnemyAI') // 重复创建
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// ... 节点定义
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.build();
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BehaviorTreeStarter.start(enemy, tree);
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}
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```
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### 2. 及时卸载不用的资产
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```typescript
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// 关卡结束时卸载该关卡的AI
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function onLevelEnd() {
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assetManager.unloadAsset('Level1BossAI');
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assetManager.unloadAsset('Level1EnemyAI');
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}
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// 加载新关卡的AI
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function onLevelStart() {
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const boss2AI = await loadTreeFromFile('/assets/level2-boss.btree.json');
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assetManager.loadAsset(boss2AI);
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}
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```
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## 完整示例：多敌人类型的游戏
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```typescript
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import { Core, Scene } from '@esengine/esengine';
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import {
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BehaviorTreePlugin,
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BehaviorTreeAssetManager,
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BehaviorTreeBuilder,
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BehaviorTreeStarter
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} from '@esengine/behavior-tree';
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async function setupGame() {
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// 1. 初始化
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Core.create();
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const plugin = new BehaviorTreePlugin();
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await Core.installPlugin(plugin);
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const scene = new Scene();
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plugin.setupScene(scene);
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Core.setScene(scene);
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const assetManager = Core.services.resolve(BehaviorTreeAssetManager);
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// 2. 创建共享的子树
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const patrolTree = BehaviorTreeBuilder.create('Patrol')
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.sequence('PatrolLoop')
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.log('巡逻')
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.wait(1.0)
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.end()
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.build();
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const combatTree = BehaviorTreeBuilder.create('Combat')
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.sequence('CombatLoop')
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.log('战斗')
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.end()
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.build();
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assetManager.loadAsset(patrolTree);
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assetManager.loadAsset(combatTree);
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// 3. 创建不同类型敌人的AI
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const meleeEnemyAI = BehaviorTreeBuilder.create('MeleeEnemyAI')
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.selector('MeleeBehavior')
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.sequence('Attack')
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.blackboardExists('target')
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.log('近战攻击')
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.end()
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.subTree('Patrol')
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.end()
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.build();
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const rangedEnemyAI = BehaviorTreeBuilder.create('RangedEnemyAI')
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.selector('RangedBehavior')
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.sequence('Attack')
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.blackboardExists('target')
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.log('远程攻击')
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.end()
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.subTree('Patrol')
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.end()
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.build();
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assetManager.loadAsset(meleeEnemyAI);
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assetManager.loadAsset(rangedEnemyAI);
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// 4. 创建多个敌人实体
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// 10个近战敌人共享同一份AI
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const meleeAI = assetManager.getAsset('MeleeEnemyAI')!;
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for (let i = 0; i < 10; i++) {
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const enemy = scene.createEntity(`MeleeEnemy${i}`);
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BehaviorTreeStarter.start(enemy, meleeAI);
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}
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// 5个远程敌人共享同一份AI
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const rangedAI = assetManager.getAsset('RangedEnemyAI')!;
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for (let i = 0; i < 5; i++) {
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const enemy = scene.createEntity(`RangedEnemy${i}`);
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BehaviorTreeStarter.start(enemy, rangedAI);
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}
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console.log(`已创建 15 个敌人，使用 ${assetManager.getAssetCount()} 个行为树资产`);
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// 5. 游戏循环
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setInterval(() => {
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Core.update(0.016);
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}, 16);
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}
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setupGame();
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```
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## 常见问题
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### 如何检查资产是否已加载？
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```typescript
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const assetManager = Core.services.resolve(BehaviorTreeAssetManager);
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if (!assetManager.hasAsset('EnemyAI')) {
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// 加载资产
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const tree = await loadTreeFromFile('/assets/enemy-ai.btree.json');
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assetManager.loadAsset(tree);
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}
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```
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### 子树找不到怎么办？
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确保子树已经加载到资产管理器中：
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```typescript
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// 1. 先加载子树
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const subTree = BehaviorTreeBuilder.create('SubTreeID')
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// ...
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.build();
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assetManager.loadAsset(subTree);
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// 2. 再加载使用子树的主树
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const mainTree = BehaviorTreeBuilder.create('MainTree')
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.subTree('SubTreeID')
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.build();
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```
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### 如何导出行为树为 JSON？
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```typescript
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import { BehaviorTreeAssetSerializer } from '@esengine/behavior-tree';
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const tree = BehaviorTreeBuilder.create('MyTree')
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// ... 节点定义
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.build();
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// 序列化为JSON字符串
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const json = BehaviorTreeAssetSerializer.serialize(tree);
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// 保存到文件或发送到服务器
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console.log(json);
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```
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## 下一步
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- 学习[Cocos Creator 集成](./cocos-integration.md)了解如何在游戏引擎中加载资源
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- 查看[自定义节点执行器](./custom-actions.md)创建自定义行为
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- 阅读[最佳实践](./best-practices.md)优化你的行为树设计
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