A node-oriented Finite State Machine for Godot (4.2+)

1. Copy all files in src to your project.
2. Rename the classes as needed if there are conflicts with the global namespace.
3. Use it normally.

This node is the root for all your states. You may have non-state nodes inside the state machine because the system would recursively detect root nodes. IMPORTANT NOTE: the first state node will be the initial state by default.

To transition between states, you may use transition to send the event to the newly created finite state machine

extends Node2D

@onready var machine = $StateMachine

func _ready():
   machine.transition('transition_here')

IMPORTANT: The name of the node IS the name of the state. Normally, you should extend the state class for each state to provide for functionality.

extends State

func on_entry():
   print("Do something when the state is entered")

func on_process():
   print("Process here")

func on_exit():
   print("Cleanup")

NOTE: Same as the StateMachine node, you may group nodes other than Transition in your state. It will detect the transitions automatically.

Transition node SHOULD be parented under state. Same as before, the name of the node is the name of the event/signal/transition. You should extend the transition node to access the lifecycle

extends Transition

func should_transition():
   # Check whether a transition should happen or not, this is the guard
   return true

func on_transition():
   print("Do something when transitioning to new state")

• States/transitions extension means there would be a lot of files just extending them, which could be VERY VERY annoying.
• Does not support async/await