feat: validates for multiple start locations set in an ESCRoom and up…

…dates scene tree with configuration warnings next to the offending ESCLocation nodes

addons/escoria-core/game/core-scripts/esc_location.gd

@@ -3,15 +3,23 @@
 # automatically use an `ESCLocation` that is a child of the destination node.
 # Commands like `turn_to`--which are not movement-based--will ignore child
 # `ESCLocation`s and refer to the parent node.
+tool
 extends Position2D
 class_name ESCLocation, "res://addons/escoria-core/design/esc_location.svg"
 
 
+signal is_start_location_set
+
+
+const MULTIPLE_START_LOCATIONS_WARNING = \
+	"Only 1 ESCLocation should have is_start_location set to true in an ESCRoom"
+
+
 # The global ID of this item
 export(String) var global_id
 
 # If true, this ESCLocation is considered as a player start location
-export(bool) var is_start_location = false
+export(bool) var is_start_location = false setget set_is_start_location
 
 # If true, player orients towards 'interaction_direction' as
 # player character arrives.
@@ -22,6 +30,9 @@ export(bool) var player_orients_on_arrival = true
 export(int) var interaction_direction
 
 
+var _multiple_start_locations_exist: bool = false setget set_multiple_locations_exist
+
+
 # Used by "is" keyword to check whether a node's class_name
 # is the same as p_classname.
 #
@@ -34,10 +45,36 @@ func is_class(p_classname: String) -> bool:
 
 # Ready function
 func _ready():
-	if not self.global_id.empty():
-		escoria.object_manager.register_object(
-			ESCObject.new(
-				self.global_id,
-				self
+	if not Engine.is_editor_hint():
+		if not self.global_id.empty():
+			escoria.object_manager.register_object(
+				ESCObject.new(
+					self.global_id,
+					self
+				)
 			)
-		)
+
+
+func _exit_tree():
+	if Engine.is_editor_hint():
+		if is_start_location:
+			emit_signal("is_start_location_set", self)
+
+
+func _get_configuration_warning():
+	if _multiple_start_locations_exist:
+		return MULTIPLE_START_LOCATIONS_WARNING
+
+	return ""
+
+
+func set_multiple_locations_exist(value: bool) -> void:
+	_multiple_start_locations_exist = value
+	update_configuration_warning()
+
+
+func set_is_start_location(value: bool) -> void:
+	is_start_location = value
+
+	if Engine.is_editor_hint() and is_instance_valid(get_owner()):
+		emit_signal("is_start_location_set")

addons/escoria-core/game/core-scripts/esc_room.gd

@@ -66,8 +66,12 @@ func _ready():
 			) != self.filename:
 		is_run_directly = true
 
-	if not Engine.is_editor_hint():
-		escoria.room_manager.init_room(self)
+	if Engine.is_editor_hint():
+		_connect_location_nodes()
+		_validate_start_locations()
+		return
+
+	escoria.room_manager.init_room(self)
 
 
 # Draw the camera limits visualization if enabled
@@ -97,6 +101,56 @@ func _draw():
 			camera_limits[i].position.y + 30), str(i), camera_limits_colors[i])
 
 
+# Listen for any signals from ESCLocation indicating that the is_start_location attribute
+# has been set/unset in order to update start location validation.
+func _connect_location_nodes() -> void:
+	_connect_location_nodes_in_tree(self)
+
+
+func _connect_location_nodes_in_tree(node: Node):
+	for n in node.get_children():
+		if n is ESCLocation:
+			if not n.is_connected("is_start_location_set", self, "_validate_start_locations"):
+				n.connect("is_start_location_set", self, "_validate_start_locations")
+
+		if n.get_child_count() > 0:
+			_connect_location_nodes_in_tree(n)
+
+
+# Validate that we only have one start location for this scene. If we don't, call it out in the
+# scene tree via configuration warnings.
+#
+# We may have to ignore a node if it's being removed/deleted from the scene tree.
+func _validate_start_locations(to_ignore: ESCLocation = null):
+	var esc_locations: Array = _find_esc_locations(self)
+	var num_start_locations: int = 0
+
+	for n in esc_locations:
+		if n == to_ignore:
+			continue
+
+		num_start_locations += 1 if n.is_start_location else 0
+
+	for n in esc_locations:
+		if n == to_ignore:
+			continue
+
+		n.set_multiple_locations_exist(n.is_start_location and num_start_locations > 1)
+
+
+func _find_esc_locations(node: Node) -> Array:
+	var esc_locations: Array = []
+
+	for n in node.get_children():
+		if n is ESCLocation:
+			esc_locations.append(n)
+
+		if n.get_child_count() > 0:
+			esc_locations.append_array(_find_esc_locations(n))
+
+	return esc_locations
+
+
 # Set the camera limits
 #
 # #### Parameters