LimboAI - Behavior Trees and Hierarchical State Machines for Godot Engine 4 --- LimboAI is a C++ module for Godot 4 that provides an implementation of Behavior Trees and State Machines, which can be used together to create complex AI behaviors. >**🛈 Supported Godot Engine: 4.1** >**🛈 License**: Use of this source code is governed by an MIT-style license that can be found in the LICENSE file or at https://opensource.org/licenses/MIT. ![Textured screenshot](doc/images/behavior-tree-editor.png) ![Textured screenshot](doc/images/behavior-tree-debugger.png) ## Features - Behavior Trees (BT): - Use the `BTPlayer` node to execute `BehaviorTree` resources. - Easily create, edit, and save `BehaviorTree` resources within the editor. - Combine and nest tasks in a hierarchy to create complex behaviors. - Control the flow of execution using composite, decorator, and condition tasks. - Write your own tasks by extending core classes: `BTAction`, `BTCondition`, `BTDecorator` and `BTComposite`. - Built-in class documentation. Check out the `BehaviorTree` and `BTTask` class documentation to get started. - Utilize the `Blackboard` for seamless data sharing between tasks. - Use the `BTSubtree` task to execute a tree from a different resource file, promoting organization and reusability. - Blackboard scopes separate namespaces of variables from subtrees, and enable advanced techniques like sharing data among agents in a group. - Visual Debugger: Inspect the execution of any BT in a running scene to identify and troubleshoot issues. - Evaluate the performance of your trees with custom performance monitors. - Hierarchical State Machine (HSM) - Extend `LimboState` class to implement state logic. - `LimboHSM` node serves as a state machine that manages `LimboState` instances and transitions. - `LimboHSM` is a state itself and can be nested within other `LimboHSM` instances. - Event-based: Transitions are associated with events, and are triggered by the state machine when the relevant event is dispatched, allowing for better decoupling of transitions from state logic. - Combine state machines with behavior trees using `BTState` for advanced reactive AI. - Delegation: Instead of extending `LimboState`, utilize vanilla `LimboState` and delegate implementation to provided callback functions. Perfect for game jams and quick prototyping. - 🛈 Note: Currently, state machine transition setup and initialization must be done through code as there is no GUI editor for state machines at the moment. ## Compiling > 🛈 Precompiled builds are a WIP To incorporate this module, you'll need to build Godot Engine from source with LimboAI module included. Building From Source: - Download the Godot Engine source code and put this module source into the `modules/limboai` directory. - Consult the Godot Engine documentation for instructions on [how to build from source code](https://docs.godotengine.org/en/stable/contributing/development/compiling/index.html). - If you plan to export a game utilizing the LimboAI module, you'll need to build export templates as well. ## Contributing All contributions are welcome! Feel free to open issues with bug reports and feature requests, and submit PRs. ## Roadmap Features and improvements that may be implemented in the future: - Providing precompiled builds for download. - Creating a non-trivial demo project to showcase the capabilities of LimboAI. - Exploring the execution history of Behavior Trees in the Visual Debugger. - Tests and CI. - Expanding the library of tasks that can be optionally included in the build. - Implementing an ignore list for tasks that users may want to hide in the task panel. - GUI editor for state machines. - Supporting GDExtension in the future, once it matures.