State Machine - State Machine skeleton for Godot Engine

The StateMachine and State nodes provide a base for adding state machines to your scenes in Godot Engine.

Usage

When creating your scene, add a StateMachine node as a child to your root, and add each state that inherits res://addons/state_machine/state.gd as a grandchild.
Call context_ready() on the state machine in your scene root's ready() function to initialize each state and set the initial state (if provided).
Each state should implement their logic in the engine defined _process(), _physics_process(), _input(), _unhandled_input() and _unhandled_key_input() functions.
When you want to transition to another state, you can emit the state_changed signal from a state with the next state's node name as the argument.

Example

Scene Structure

Player (KinematicBody2D)
 - StateMachine (StateMachine)
    - Idle (Node / "idle.gd" script)
	- Moving (Node / "moving.gd" script)

It is assumed that StateMachine has been provided with Idle as the Initial State exported NodePath.

Scripts

player.gd

...
const StateMachine := preload("res://addons/state_machine/state_machine.gd")
func _ready() -> void:
	var state_machine := $StateMachine as StateMachine
	state_machine.context_ready()
...

idle.gd

extends "res://addons/state_machine/state.gd"


func start() -> void:
	_context.set_idle_animation()


func _unhandled_key_input(_event: InputEventKey) -> void:
	if Input.is_action_just_pressed("ui_left") or Input.is_action_just_pressed("ui_right"):
		emit_signal("state_finished", "Moving")

moving.gd

extends "res://addons/state_machine/state.gd"


func start() -> void:
	_context.set_moving_animation()


func _phisics_process(delta: float) -> void:
	_context.move(delta)


func _unhandled_key_input(_event: InputEventKey) -> void:
	if Input.is_action_just_released("ui_left") or Input.is_action_just_released("ui_right"):
		emit_signal("state_finished", "Idle")