Checkpoint: Add tile change persistence

scenes/dev/level_design/void_persistence/quest.tres

@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="Quest" format=3 uid="uid://28abe4vgj3ul"]
+
+[ext_resource type="Script" uid="uid://dts1hwdy3phin" path="res://scenes/menus/storybook/components/quest.gd" id="1_ikuea"]
+
+[resource]
+script = ExtResource("1_ikuea")
+title = "Void Persistence"
+description = "Learn how to set up your checkpoints for persistent enemies!"
+first_scene = "uid://dwgvjv2wxnr0k"
+threads_to_collect = 0
+metadata/_custom_type_script = "uid://dts1hwdy3phin"

scenes/game_elements/characters/enemies/void_spreading_enemy/components/tile_map_cover.gd

@@ -24,6 +24,9 @@ const _DURATION: float = 0.25
 ## Nodes whose direct children (but not grandchildren) can be consumed.
 @export var consumable_node_holders: Array[Node]
 
+## Wether to save the tilemap cover in this scene state.
+@export var save_state: bool
+
 var _unconsumed_nodes: Dictionary[Vector2i, Array] = { }
 var _consumed_nodes: Dictionary[Vector2i, Array] = { }
 
@@ -101,6 +104,9 @@ func _ready() -> void:
 		return
 
 	for parent: Node in consumable_node_holders:
+		# Filter unsassigned elements:
+		if parent == null:
+			continue
 		for child: Node in parent.get_children():
 			if child is Node2D:
 				var coord := coord_for(child)
@@ -110,6 +116,9 @@ func _ready() -> void:
 
 	for coord: Vector2i in get_used_cells():
 		consume(coord, true)
+	if save_state:
+		GameState.scene.checkpoint_activated.connect(_on_checkpoint_activated)
+		_load_state()
 
 
 ## Cover all [param cells] with [member terrain_name], hiding any nodes in those cells which are
@@ -179,3 +188,18 @@ func uncover_all(duration: float, animate_modulate: bool = false) -> void:
 	clear()
 	if animate_modulate:
 		self.modulate.a = 1.0
+
+
+## Responds to the checkpoint's activated signal and saves consumed tiles.
+func _on_checkpoint_activated() -> void:
+	var save_key := str(get_path())
+	GameState.scene.facts[save_key] = get_used_cells()
+
+
+## Reconstructs the holes in the TileMap immediately on scene load.
+## Executes without animation to prevent visual glitches upon respawn.
+func _load_state() -> void:
+	var save_key := str(get_path())
+	if GameState.scene.facts.has(save_key):
+		var saved_tiles: Array = GameState.scene.facts[save_key]
+		consume_cells(saved_tiles, true)

scenes/game_elements/characters/enemies/void_spreading_enemy/components/void_spreading_enemy.gd

@@ -40,6 +40,9 @@ const IDLE_EMIT_DISTANCE := sqrt(2 * (64.0 ** 2))
 ## area)
 @export var void_particles: PackedScene
 
+## Wether to save the enemy position and direction in this scene state.
+@export var save_state: bool
+
 var node_to_follow: Node2D:
 	set = _set_node_to_follow
 
@@ -134,6 +137,11 @@ func _ready() -> void:
 	if Engine.is_editor_hint():
 		set_process(false)
 		set_physics_process(false)
+		return
+
+	if save_state:
+		GameState.scene.checkpoint_activated.connect(_on_checkpoint_activated)
+		_load_state()
 
 
 func start(detected_node: Node2D) -> void:
@@ -202,3 +210,31 @@ func _on_player_capture_area_body_entered(body: Node2D) -> void:
 
 	var player := body as Player
 	player.defeat(true)
+
+
+## Responds to the checkpoint's activated signal and records position and path progress.
+func _on_checkpoint_activated() -> void:
+	var save_key := str(get_path())
+	var data := { "global_position": global_position, "last_position": _last_position }
+
+	if path_walk_behavior:
+		data["path_direction"] = path_walk_behavior.direction
+
+	GameState.scene.facts[save_key] = data
+
+
+## Reconstructs the enemy's exact position and path progress on scene load.
+## Prevents massive particle bursts caused by teleportation.
+func _load_state() -> void:
+	if GameState.scene == null or not "facts" in GameState.scene:
+		return
+
+	var save_key := str(get_path())
+	if GameState.scene.facts.has(save_key):
+		var data: Dictionary = GameState.scene.facts[save_key]
+
+		global_position = data["global_position"]
+		_last_position = data["last_position"]
+
+		if path_walk_behavior and data.has("path_direction"):
+			path_walk_behavior.direction = data["path_direction"]

scenes/game_elements/props/checkpoint/components/checkpoint.gd

@@ -29,6 +29,10 @@ const REQUIRED_ANIMATIONS := [&"idle", &"appear"]
 ## be able to interact with the checkpoint.
 @export var dialogue: DialogueResource = preload("uid://bug2aqd47jgyu")
 
+## Determines if the enemies and the void layer should save their state when
+## the player activates this checkpoint.
+@export var save_void_and_enemies: bool = false
+
 ## The point where the player will spawn.
 @onready var spawn_point: SpawnPoint = %SpawnPoint
 
@@ -75,6 +79,7 @@ func _ready() -> void:
 
 ## Makes this the active checkpoint.
 func activate() -> void:
+	GameState.scene.activate_checkpoint()
 	GameState.scene.spawn_point = owner.get_path_to(spawn_point)
 	GameState.save()
 

scenes/globals/game_state/per_scene_state.gd

@@ -12,6 +12,9 @@ extends Resource
 ## lights should turn on gradually.
 signal lights_changed(lights_on: bool, immediate: bool)
 
+## Emitted when the player activates a checkpoint.
+signal checkpoint_activated
+
 ## The path to the current scene.
 @export var path: String
 
@@ -24,6 +27,9 @@ signal lights_changed(lights_on: bool, immediate: bool)
 ## Set when any introductory dialogue has been played for the current scene.
 @export var intro_dialogue_shown: bool
 
+## Dictionary to store arbitrary persistent scene facts, such as enemy states and consumed tiles.
+@export var facts: Dictionary = { }
+
 ## Current state of artificial lights. Set with [member set_lights_on]. This is
 ## not saved to disk since the lights are controlled programmatically.
 var lights_on: bool
@@ -45,6 +51,10 @@ func set_lights_on(new_value: bool, immediate: bool = false) -> void:
 	lights_changed.emit(new_value, immediate)
 
 
+func activate_checkpoint() -> void:
+	checkpoint_activated.emit()
+
+
 func set_spawn_point(new_value: NodePath) -> void:
 	spawn_point = new_value
 	emit_changed()