Added a multithreading loading

I just replaced load(scene_path) with ResourceLoader.load_threaded_request(scene_path) and placed await in the code.
Now, when scenes with characters are loaded, there are no freezes in the main thread.
I used a complex custom scene with Spine animations and 4k atlas textures.

Author: RightSorcerer

addons/dialogic/Modules/Character/subsystem_portraits.gd

@@ -35,10 +35,22 @@ func load_game_state(_load_flag:=LoadFlags.FULL_LOAD) -> void:
 		var character_info: Dictionary = portraits_info[character_path]
 		var character: DialogicCharacter = load(character_path)
 		var container := dialogic.PortraitContainers.load_position_container(character.get_character_name())
-		add_character(character, container, character_info.portrait, character_info.position_id)
-		change_character_mirror(character, character_info.get('custom_mirror', false))
-		change_character_z_index(character, character_info.get('z_index', 0))
-		change_character_extradata(character, character_info.get('extra_data', ""))
+		
+		ResourceLoader.load_threaded_request(character_path)
+
+		var load_status = ResourceLoader.load_threaded_get_status(character_path)
+		while load_status == ResourceLoader.THREAD_LOAD_IN_PROGRESS:
+			await get_tree().process_frame
+			load_status = ResourceLoader.load_threaded_get_status(character_path)
+
+		if load_status == ResourceLoader.THREAD_LOAD_LOADED:
+			character = ResourceLoader.load_threaded_get(character_path)
+			add_character(character, container, character_info.portrait, character_info.position_id)
+			change_character_mirror(character, character_info.get('custom_mirror', false))
+			change_character_z_index(character, character_info.get('z_index', 0))
+			change_character_extradata(character, character_info.get('extra_data', ""))
+		else:
+			push_error('[Dialogic] Failed to load character "' + str(character_path) + '".')
 
 	# Load Speaker Portrait
 	var speaker: Variant = dialogic.current_state_info.get('speaker', "")
@@ -117,19 +129,29 @@ func _change_portrait(character_node: Node2D, portrait: String, fade_animation:=
 	if (not previous_portrait == null and
 		previous_portrait.get_meta('scene', '') == scene_path and
 		# Also check if the scene supports changing to the given portrait.
+		previous_portrait.has_method('_should_do_portrait_update') and
 		previous_portrait._should_do_portrait_update(character, portrait)):
 			portrait_node = previous_portrait
 			info['same_scene'] = true
 
 	else:
 
 		if ResourceLoader.exists(scene_path):
-			var packed_scene: PackedScene = load(scene_path)
+			ResourceLoader.load_threaded_request(scene_path)
+			
+			var load_status = ResourceLoader.load_threaded_get_status(scene_path)
+			while load_status == ResourceLoader.THREAD_LOAD_IN_PROGRESS:
+				await get_tree().process_frame
+				load_status = ResourceLoader.load_threaded_get_status(scene_path)
 
-			if packed_scene:
-				portrait_node = packed_scene.instantiate()
+			if load_status == ResourceLoader.THREAD_LOAD_LOADED:
+				var packed_scene: PackedScene = ResourceLoader.load_threaded_get(scene_path)
+				if packed_scene:
+					portrait_node = packed_scene.instantiate()
+				else:
+					push_error('[Dialogic] Portrait node "' + str(scene_path) + '" for character [' + character.display_name + '] could not be loaded. Your portrait might not show up on the screen. Confirm the path is correct.')
 			else:
-				push_error('[Dialogic] Portrait node "' + str(scene_path) + '" for character [' + character.display_name + '] could not be loaded. Your portrait might not show up on the screen. Confirm the path is correct.')
+				push_error('[Dialogic] Failed to load portrait node "' + str(scene_path) + '" for character [' + character.display_name + '].')
 
 		if !portrait_node:
 			portrait_node = default_portrait_scene.instantiate()
@@ -156,7 +178,8 @@ func _change_portrait(character_node: Node2D, portrait: String, fade_animation:=
 			if not fade_animation.is_empty() and fade_length > 0:
 				var fade_out := _animate_node(previous_portrait, fade_animation, fade_length, 1, true)
 				var _fade_in := _animate_node(portrait_node, fade_animation, fade_length, 1, false)
-				fade_out.finished.connect(previous_portrait.queue_free)
+				await fade_out.finished
+				previous_portrait.queue_free()
 			else:
 				previous_portrait.queue_free()
 
@@ -167,20 +190,27 @@ func _change_portrait(character_node: Node2D, portrait: String, fade_animation:=
 ## Unless @force is false, this will take into consideration the character mirror,
 ## portrait mirror and portrait position mirror settings.
 func _change_portrait_mirror(character_node: Node2D, mirrored := false, force := false) -> void:
-	var latest_portrait := character_node.get_child(-1)
+	var latest_portrait := character_node.get_child(-1) 
+	if character_node.get_child_count() > 0 else null
 
-	if latest_portrait.has_method('_set_mirror'):
+	if latest_portrait and latest_portrait.has_method("_set_mirror"):
 		var character: DialogicCharacter = character_node.get_meta('character')
 		var current_portrait_info := character.get_portrait_info(character_node.get_meta('portrait'))
 		latest_portrait._set_mirror(force or (mirrored != character.mirror != character_node.get_parent().mirrored != current_portrait_info.get('mirror', false)))
 
 
 func _change_portrait_extradata(character_node: Node2D, extra_data := "") -> void:
-	var latest_portrait := character_node.get_child(-1)
+	if not is_instance_valid(character_node):
+		push_error("[Dialogic] Invalid character node provided.")
+		return
 
-	if latest_portrait.has_method('_set_extra_data'):
-		latest_portrait._set_extra_data(extra_data)
+	if character_node.get_child_count() > 0:
+		var latest_portrait := character_node.get_child(-1)
 
+		if latest_portrait and latest_portrait.has_method("_set_extra_data"):
+			latest_portrait._set_extra_data(extra_data)
+	else:
+		push_warning("[Dialogic] No portrait found for character node: " + character_node.name)
 
 func _update_character_transform(character_node:Node, time := 0.0) -> void:
 	for child in character_node.get_children():
@@ -379,7 +409,7 @@ func join_character(character:DialogicCharacter, portrait:String,  position_id:S
 		return
 
 	var container := dialogic.PortraitContainers.add_container(character.get_character_name())
-	var character_node := add_character(character, container, portrait, position_id)
+	var character_node := await add_character(character, container, portrait, position_id)
 	if character_node == null:
 		return null
 
@@ -410,9 +440,9 @@ func join_character(character:DialogicCharacter, portrait:String,  position_id:S
 	return character_node
 
 
-func add_character(character:DialogicCharacter, container: DialogicNode_PortraitContainer, portrait:String,  position_id:String) -> Node:
+func add_character(character: DialogicCharacter, container: DialogicNode_PortraitContainer, portrait: String, position_id: String) -> Node:
 	if is_character_joined(character):
-		printerr('[DialogicError] Cannot add a already joined character. If this is intended call _create_character_node manually.')
+		printerr('[DialogicError] Cannot add an already joined character. If this is intended, call _create_character_node manually.')
 		return null
 
 	portrait = get_valid_portrait(character, portrait)
@@ -423,21 +453,31 @@ func add_character(character:DialogicCharacter, container: DialogicNode_Portrait
 	if not character:
 		printerr('[DialogicError] Cannot call add_portrait() with null character.')
 		return null
+	
+	ResourceLoader.load_threaded_request(character.resource_path)
+	
+	var load_status = ResourceLoader.load_threaded_get_status(character.resource_path)
+	while load_status == ResourceLoader.THREAD_LOAD_IN_PROGRESS:
+		await get_tree().process_frame
+		load_status = ResourceLoader.load_threaded_get_status(character.resource_path)
 
-	var character_node := _create_character_node(character, container)
-
-	if character_node == null:
-		printerr('[Dialogic] Failed to join character to position ', position_id, ". Could not find position container.")
-		return null
-
+	if load_status == ResourceLoader.THREAD_LOAD_LOADED:
+		character = ResourceLoader.load_threaded_get(character.resource_path)
+		var character_node := _create_character_node(character, container)
 
-	dialogic.current_state_info['portraits'][character.resource_path] = {'portrait':portrait, 'node':character_node, 'position_id':position_id}
+		if character_node == null:
+			printerr('[Dialogic] Failed to join character to position ', position_id, ". Could not find position container.")
+			return null
 
-	_move_character(character_node, position_id)
-	_change_portrait(character_node, portrait)
+		dialogic.current_state_info['portraits'][character.resource_path] = {'portrait': portrait, 'node': character_node, 'position_id': position_id}
 
-	return character_node
+		_move_character(character_node, position_id)
+		await _change_portrait(character_node, portrait)
 
+		return character_node
+	else:
+		push_error('[Dialogic] Failed to load character "' + str(character.resource_path) + '".')
+		return null
 
 ## Changes the portrait of a character. Only works with joined characters.
 func change_character_portrait(character: DialogicCharacter, portrait: String, fade_animation:="DEFAULT", fade_length := -1.0) -> void:
@@ -455,7 +495,7 @@ func change_character_portrait(character: DialogicCharacter, portrait: String, f
 
 	fade_animation = DialogicPortraitAnimationUtil.guess_animation(fade_animation, DialogicPortraitAnimationUtil.AnimationType.CROSSFADE)
 
-	var info := _change_portrait(dialogic.current_state_info.portraits[character.resource_path].node, portrait, fade_animation, fade_length)
+	var info := await _change_portrait(dialogic.current_state_info.portraits[character.resource_path].node, portrait, fade_animation, fade_length)
 	dialogic.current_state_info.portraits[character.resource_path].portrait = info.portrait
 	_change_portrait_mirror(
 			dialogic.current_state_info.portraits[character.resource_path].node,
@@ -629,7 +669,8 @@ func change_speaker(speaker: DialogicCharacter = null, portrait := "") -> void:
 
 				if leave_animation and leave_animation_length:
 					var animate_out := _animate_node(character_node, leave_animation, leave_animation_length, 1, true)
-					animate_out.finished.connect(character_node.queue_free)
+					await animate_out.finished
+					character_node.queue_free()
 				else:
 					character_node.get_parent().remove_child(character_node)
 					character_node.queue_free()
@@ -640,7 +681,19 @@ func change_speaker(speaker: DialogicCharacter = null, portrait := "") -> void:
 			continue
 
 		if just_joined:
-			_create_character_node(speaker, container)
+			ResourceLoader.load_threaded_request(speaker.resource_path)
+
+			var load_status = ResourceLoader.load_threaded_get_status(speaker.resource_path)
+			while load_status == ResourceLoader.THREAD_LOAD_IN_PROGRESS:
+				await get_tree().process_frame
+				load_status = ResourceLoader.load_threaded_get_status(speaker.resource_path)
+
+			if load_status == ResourceLoader.THREAD_LOAD_LOADED:
+				speaker = ResourceLoader.load_threaded_get(speaker.resource_path)
+				_create_character_node(speaker, container)
+			else:
+				push_error('[Dialogic] Failed to load speaker "' + str(speaker.resource_path) + '".')
+				continue
 
 		elif portrait.is_empty():
 			continue
@@ -655,10 +708,10 @@ func change_speaker(speaker: DialogicCharacter = null, portrait := "") -> void:
 
 		fade_animation = DialogicPortraitAnimationUtil.guess_animation(fade_animation, DialogicPortraitAnimationUtil.AnimationType.CROSSFADE)
 
-		if container.portrait_prefix+portrait in speaker.portraits:
-			portrait = container.portrait_prefix+portrait
+		if container.portrait_prefix + portrait in speaker.portraits:
+			portrait = container.portrait_prefix + portrait
 
-		_change_portrait(character_node, portrait, fade_animation, fade_length)
+		await _change_portrait(character_node, portrait, fade_animation, fade_length)
 
 		# if the character has no portraits _change_portrait won't actually add a child node
 		if character_node.get_child_count() == 0:
@@ -677,7 +730,7 @@ func change_speaker(speaker: DialogicCharacter = null, portrait := "") -> void:
 			var join_animation_length := _get_join_default_length()
 
 			if join_animation and join_animation_length:
-				_animate_node(character_node, join_animation, join_animation_length)
+				await _animate_node(character_node, join_animation, join_animation_length).finished
 
 		_change_portrait_mirror(character_node)