Trouble with state machines

Help
1

Godot Version

4.3

Question

i followed this tutorial and made a state machine. now however, i want to change the state from a parent node. I’ve tried state.Transition.emit(true, “follow”) and all that but nothing is working

2

Can you paste your script? Videos are really bad for sifting through. For example scrubbing through that video I do not see signal Transition defined, though they use Transition.emit(self, "idle")

3

this is set up to either follow the player or have free cam

image

state machine node

extends Node

@export var initial_state : State

var current_state : State
var states : Dictionary = {}

func _ready():
	
	for child in get_children():
		if child is State:
			states[child.name.to_lower()] = child
			child.Transitioned.connect(on_child_transition)
	if initial_state:
		initial_state.Enter()
		current_state = initial_state
	
	
func _process(delta: float):
	print(current_state)
	if current_state:
		current_state.Update(delta)
func _physics_process(delta: float):
	if current_state:
		current_state.Update(delta)
func on_child_transition(state, new_state_name):
	if state != current_state:
		return
	
	var new_state = states.get(new_state_name.to_lower())
	if !new_state:
		return
		
	if current_state:
		current_state.Exit()
	new_state.Enter()
	
	current_state = new_state

follow state

extends State
class_name cameraFollow

@export var camera: Camera2D

func Enter():
	follow()
	camera.targetZoom = Vector2(2, 2)

func follow():
	if camera.target != "":
		var targetPos = Global.NODE_WORLD.get_node(camera.target).position
		camera.position += (targetPos - camera.position) / camera.smooth
	
	

func Update(delta):
	follow()

free state

class_name cameraFree

@export var camera: Camera2D
var dragVel = Vector2(0, 0)
var oldMousePos = Vector2(0, 0)
var termDragVel = Vector2(10, 10)
func Enter():
	camera.targetZoom = Vector2(4, 4)
	

func Update(delta: float) -> void:
	var mousePos = camera.get_viewport().get_mouse_position()
	if Input.is_action_pressed("lClick"):
		dragVel -= dragVel / 10
		if oldMousePos != mousePos:
			dragVel = (oldMousePos - mousePos)/2
		camera.position += (oldMousePos - mousePos)/camera.zoom
	else:
		camera.position += dragVel
		dragVel -= dragVel / 10
		if abs(dragVel.x) > termDragVel.x:
			dragVel.x = termDragVel.x * sign(dragVel.x)
		if abs(dragVel.y) > termDragVel.y:
			dragVel.y = termDragVel.y * sign(dragVel.y)
	oldMousePos = mousePos
4

Again I don’t see a signal Transition defined, I would bet it’s part of your base State script. Eitherway This line is probably what prevents you from changing states and does nothing.

Your first argument true is not a state or node, so it will return early, doing nothing. I believe you do not want this check at all so it may be better to remove the state argument and the if statement that follows.

5

i forgot to meantion there is a state script that has

extends Node
class_name State

signal Transitioned

func Enter():
	pass
func Exit():
	pass
func Update(_delta: float):
	pass
func Physics_Update(_delta: float):
	pass

inside it. however I think this problem might be too specific for anyone to answer, i gave the code to chat gpt and it told me to put

func change_state(new_state: State):
	if current_state:
		current_state.Exit()
	current_state = new_state
	if current_state:
		current_state.Enter()

inside of the state machine node and then call

var new_state = $StateMachineNode.states["camera_follow"]
$StateMachineNode.change_state(new_state)

in another node. sorry to waste your time but ill give you the solution mark anyway

6

You do already have that code in your script.

Is in the state machine script here:

The latter just has more checks, and the functional part is simpler. You could use

$StateMachineNode.on_child_transition($StateMachineNode.current_state, "camera_follow")

But that’s why I’m saying the function is made with too many silly checks. I would remove all these commented lines

func on_child_transition(new_state_name: String): # removed 'state' argument.
	#if state != current_state:
		#return
	
	var new_state = states.get(new_state_name.to_lower())
	#if !new_state: # allow it to error or use an assert
		#return
		
	if current_state:
		current_state.Exit()
	new_state.Enter()
	
	current_state = new_state

And now you can use

$StateMachineNode.on_child_transition("camera_follow")