Duplicating Nodes with @onready Variables

gaborit

Hello everyone,

I'm working on a turn-based tactical game in Godot and am currently trying to develop the AI logic. My approach to this is to score different outcomes based on possible actions the AI can take. To achieve this, I'm attempting to duplicate the main combat logic nodes to simulate and evaluate different scenarios without affecting the main game state.

However, I've run into an issue where the duplicate() method doesn't seem to copy the @onready variables, causing them to be lost in the duplicated nodes.

To address this, I've written a custom duplicate function, but it's cumbersome and doesn't handle grandchildren nodes or deeper hierarchies:

func duplicate_object(OBJ):
	var OBJ2 = OBJ.duplicate()
	var l=OBJ.get_property_list()
	for property in l:
		if property.usage & PROPERTY_USAGE_SCRIPT_VARIABLE:
			if is_instance_valid(OBJ.get(property.name)):
				var prop=OBJ.get(property.name)
				if prop is Node or prop is Resource:
					OBJ2.set(property.name, prop.duplicate())
				else :
					OBJ2.set(property.name, prop)
	return OBJ2

Are there better ways or best practices for duplicating nodes, especially when dealing with @onready variables?
How can I enhance this function to duplicate grandchildren nodes or deeper hierarchies?

Any insights, optimizations, or alternative approaches would be greatly appreciated. Thank you in advance!

xyz

gaborit Use scenes if you need multiple instances of a branch of nodes.

gaborit

xyz What do you mean exactly, I should save these node as scenes and the load them with the data?

xyz

gaborit A scene that you save onto disk can be loaded and instantiated from a script. You can make as many instances as you need. My suggestion is to read introductory chapters on scenes and instantiation in Godot's official docs.

gaborit

xyz For example, I have a scene "battlefield.tscn". What you are telling me is I should do something like this?

func save_scene_to_file(root_node: Node, path: String):
   var packed_scene = PackedScene.new()
   packed_scene.pack(root_node)
   ResourceSaver.save(path, packed_scene)`

func ai_script()
   save_scene_to_file(battlefield, "res://battlefield2.tscn")

   #iterate over options
      var battlefield2= preload("res://battlefield2.tscn").instanciate()
      root.add_child(battlefield2)
      #change battlefield2 and then evaluate

xyz

gaborit You don't need to save the scene in the script. Instead use the editor and make a scene out of constellation of nodes you plan to duplicate. This is sort of main architectural idea in Godot - every reusable component should be constructed as a scene.

for i in 10:
	add_child(load("res://battlefield.tscn").instantiate())

gaborit

But battlefield.tscn has the gamestate of turn 1, and I need the gamestate of the current turn.

xyz

gaborit Then make the state easy to set/transfer via functionality in scene's top node. If your state is represented by complex node configurations that vary greatly between states, then you can serialize and re-instantiate the current state as you did in your example. But the former approach is generally better.

The optimal way would be to keep all of the state data in a Resource derived class for easy serialization and have methods in scene's top node to get/set the state from/to that resource object.