Getting Started

Installation

npm install @esengine/behavior-tree

Basic Setup

import { Core, Scene } from '@esengine/ecs-framework';
import { BehaviorTreePlugin } from '@esengine/behavior-tree';

// Initialize Core
Core.create();

// Install behavior tree plugin
const plugin = new BehaviorTreePlugin();
await Core.installPlugin(plugin);

// Create and setup scene
const scene = new Scene();
plugin.setupScene(scene);
Core.setScene(scene);

Creating Your First Behavior Tree

Using Builder API

import { BehaviorTreeBuilder, BehaviorTreeStarter } from '@esengine/behavior-tree';

// Build behavior tree
const patrolAI = BehaviorTreeBuilder.create('PatrolAI')
    .defineBlackboardVariable('targetPosition', null)
    .sequence('PatrolSequence')
        .log('Start patrol', 'Patrol')
        .wait(2000)
        .log('Move to next point', 'Patrol')
    .end()
    .build();

// Attach to entity
const entity = scene.createEntity('Guard');
BehaviorTreeStarter.start(entity, patrolAI);

Node Types

Node Type	Description
Sequence	Executes children in order until one fails
Selector	Tries children until one succeeds
Parallel	Executes all children simultaneously
Action	Performs a specific action
Condition	Checks a condition
Decorator	Modifies child behavior

Blackboard Variables

The blackboard is a shared data store for behavior tree nodes:

const tree = BehaviorTreeBuilder.create('EnemyAI')
    // Define variables
    .defineBlackboardVariable('health', 100)
    .defineBlackboardVariable('target', null)
    .defineBlackboardVariable('isAlert', false)

    .selector('Main')
        // Use blackboard in conditions
        .sequence('AttackBranch')
            .blackboardCompare('health', 30, 'greater')
            .blackboardCondition('target', (t) => t !== null)
            .log('Attacking', 'Combat')
        .end()
        .log('Retreating', 'Combat')
    .end()
    .build();

Running the Behavior Tree

// The behavior tree runs automatically via ECS system
// Just create the entity and start the tree

const enemy = scene.createEntity('Enemy');
BehaviorTreeStarter.start(enemy, patrolAI);

// Access runtime for debugging
const runtime = enemy.getComponent(BehaviorTreeRuntimeComponent);
console.log('Current state:', runtime.state);

Next Steps

• Core Concepts - Understand nodes and execution
• Custom Actions - Create your own nodes
• Editor Guide - Visual tree creation