See the current and previous states of an AnimationNodeStateMachine

state_machine_history_label.gd

# StateMachineHistoryLabel.gd
# Debug UI for AnimationNodeStateMachinePlayback
# Horizontal rolling history, arrows, newest entry pulse
class_name StateMachineHistoryLabel
extends Control

@export var animation_tree: AnimationTree
@export var state_machine_path: StringName

@export var max_entries: int = 8
@export var persistent_count: int = 2
@export var fade_delay: float = 0.5
@export var fade_duration: float = 1.0

@export var bright_color: Color = Color(1, 1, 1, 1)
@export var dim_color: Color = Color(0.7, 0.7, 0.7, 1)
@export var min_alpha: float = 0.25

@export var newest_scale: float = 1.15
@export var scale_decay_duration: float = 0.2

# Internal container for labels
var _container: HBoxContainer
var _playback: AnimationNodeStateMachinePlayback
var _current_state: StringName = &""
var _entries: Array[Dictionary] = []


func _ready() -> void:
	assert(animation_tree != null)

	_container = HBoxContainer.new()
	_container.alignment = BoxContainer.ALIGNMENT_END
	_container.size_flags_horizontal = Control.SIZE_EXPAND_FILL
	_container.size_flags_vertical = Control.SIZE_FILL
	_container.mouse_filter = Control.MOUSE_FILTER_IGNORE

	var spacer := Control.new()
	spacer.size_flags_horizontal = Control.SIZE_EXPAND_FILL
	_container.add_child(spacer)

	add_child(_container)

	# Resolve playback node
	_playback = animation_tree.get(_resolve_playback_path(state_machine_path))
	assert(_playback != null)


func _process(delta: float) -> void:
	if _playback == null:
		return

	var state: StringName = _playback.get_current_node()
	if state != _current_state:
		_current_state = state
		_push_state(state)

	_update_entries(delta)
	_update_labels(delta)


func _push_state(state: StringName) -> void:
	_entries.append({ "state": state, "age": 0.0 })
	if _entries.size() > max_entries:
		_entries.pop_front()


func _update_entries(delta: float) -> void:
	for entry in _entries:
		entry.age += delta


func _update_labels(delta: float) -> void:
	_ensure_label_count(_entries.size())

	var labels: Array[RichTextLabel] = []
	for child in _container.get_children():
		if child is RichTextLabel:
			labels.append(child)

	for i in _entries.size():
		var entry := _entries[i]
		var label := labels[i]

		var is_newest: bool = i == _entries.size() - 1
		var is_persistent: bool = i >= _entries.size() - persistent_count

		label.bbcode_enabled = true
		label.text = _format_entry(entry.state, is_newest, i)

		var alpha: float = _compute_alpha(entry.age, is_persistent)
		var color: Color = bright_color if is_newest else dim_color
		color.a *= alpha
		label.modulate = color

		_update_scale(label, entry.age, is_newest)


func _update_scale(label: Control, age: float, is_newest: bool) -> void:
	if not is_newest:
		label.scale = Vector2.ONE
		return

	var t: float = clampf(age / scale_decay_duration, 0.0, 1.0)
	label.scale = Vector2.ONE.lerp(Vector2.ONE * newest_scale, 1.0 - t)


func _compute_alpha(age: float, persistent: bool) -> float:
	if persistent:
		return 1.0
	if age <= fade_delay:
		return 1.0

	var t: float = (age - fade_delay) / fade_duration
	return clamp(1.0 - t, min_alpha, 1.0)


func _format_entry(state: StringName, is_newest: bool, index: int) -> String:
	var text: String = str(state)
	if not is_newest and index < _entries.size() - 1:
		text += " →"
	if is_newest:
		text = "[b]%s[/b]" % text
	return "[font_size=24]%s[/font_size]" % text


func _ensure_label_count(count: int) -> void:
	var labels: Array[RichTextLabel] = []
	for child in _container.get_children():
		if child is RichTextLabel:
			labels.append(child)

	# Add missing labels
	while labels.size() < count:
		var lbl := _create_label()
		_container.add_child(lbl)
		labels.append(lbl)

	# Remove excess labels
	while labels.size() > count:
		var child := labels.pop_front() as RichTextLabel
		_container.remove_child(child)
		child.queue_free()


func _create_label() -> RichTextLabel:
	var lbl := RichTextLabel.new()
	lbl.fit_content = true
	lbl.scroll_active = false
	lbl.bbcode_enabled = true
	lbl.mouse_filter = Control.MOUSE_FILTER_IGNORE
	lbl.autowrap_mode = TextServer.AUTOWRAP_OFF
	return lbl


func _resolve_playback_path(path: StringName) -> StringName:
	if path.begins_with("parameters/"):
		return path if path.ends_with("/playback") else StringName("%s/playback" % path)
	return "parameters/%s/playback" % path

sm-debug.mp4