A flexible, extensible behavior tree framework for Godot 4.x that makes it easy to create complex AI behaviors for your games.

GodotBT provides a complete behavior tree implementation for the Godot Engine, allowing you to create sophisticated AI behaviors with a clear, modular structure. The framework follows behavior tree design principles with a focus on reusability and separation of concerns.

• Complete Behavior Tree Implementation: Core composite nodes, decorators, services, tasks, and conditions
• Reusable Behavior Trees: Define a behavior tree once and use it across multiple agents with their own contexts
• Blackboard System: Flexible data sharing between nodes with typed accessors and change detection
• Reactive Conditions: Trigger behavior changes based on world events with configurable abort scopes
• Service System: Run periodic background tasks with customizable frequency
• Context Separation: Each agent maintains its own execution context with the shared tree
• Utility Components: Helpers like BTTargetKey for simplified movement and targeting operations
• Example Implementation: Includes a complete demo with enemies that can patrol, chase the player, and react to events

• BTSelector: Runs child nodes until one succeeds or all fail
• BTSequence: Runs child nodes until one fails or all succeed
• BTParallel: Runs all child nodes simultaneously
• BTRandomSelector/BTRandomSequence: Random execution order versions of selector and sequence

• BTInverter: Inverts the result of a node
• BTRepeater: Repeats a node a specified number of times
• BTRepeatUntil: Repeats a node until it returns a specific result
• BTAlwaysReturn: Forces a node to return a specific result

• BTBlackboardBasedCondition: Condition based on blackboard values
• BTReactiveCondition: Condition that can trigger aborts
• BTCheckNonZeroBBEntry: Checks if a blackboard value is non-zero/non-empty
• BTCompareBBEntries: Compares two blackboard entries

• BTService: Base class for services that run periodically
• Custom services in examples like BTPlayerDetector, BTPatrolPathFollower

• BTTask: Base class for leaf nodes that perform actions
• BTWait: Wait for a specified amount of time
• Example implementations for movement, path finding, and more

1. Clone or download this repository
2. Copy the addons/godot_bt folder into your project's addons folder
3. Enable the plugin in Project Settings > Plugins

1. Create a new scene with a root node of type BehaviorTree
2. Add a BTSelector or BTSequence as the first child
3. Build your behavior tree by adding more composite nodes and tasks
4. Save the scene

# Level.gd - Sets up the behavior tree and passes it to agents extends Node2D func _ready(): # Find all agents and set their behavior trees for enemy in get_tree().get_nodes_in_group("enemies"): enemy.run_behavior_tree()

# Enemy.gd - Each agent handles its own context extends CharacterBody2D @export var bt: BehaviorTree @export var patrol_path: Node2D var ctx: BTContext # Called by the level or manager func run_behavior_tree() -> void: if not is_instance_valid(bt): return ctx = bt.create_context(self, Blackboard.new()) # Set up blackboard values for this agent if patrol_path: var patrol_points: Array = [] for patrol_pt in patrol_path.get_children(): patrol_points.append(patrol_pt.global_position) ctx.blackboard.set_value("patrol_points", patrol_points) func _physics_process(delta: float) -> void: if is_instance_valid(bt) and ctx: bt.tick(ctx, delta)

The included example demonstrates:

1. Enemy Patrol System: Enemies follow patrol paths or look in random directions
2. Player Detection: A service that detects the player within a specified range
3. Chase Behavior: Enemies chase the player when detected
4. Navigation: Path finding to navigate around obstacles

To see the example in action, open the example/TestLevel.tscn scene.

The GodotBT framework is designed to be highly extensible. You can:

class_name MyCustomTask extends BTTask @export var _some_parameter: float = 1.0 func _tick(ctx: BTContext) -> BTResult: # Your implementation here if some_condition: return BTResult.SUCCESS else: return BTResult.RUNNING

class_name MyCustomCondition extends BTCondition func _tick(ctx: BTContext) -> bool: # Your implementation here return some_condition_check

class_name MyCustomService extends BTService func _tick(ctx: BTContext) -> void: # Your implementation here ctx.blackboard.set_value("some_key", calculate_some_value())

This project is available under the MIT License.

Contributions are welcome! Feel free to submit pull requests or open issues for bugs and feature requests.