How to get the value of a variable from another scene ?

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:bust_in_silhouette: Asked By Leandro

Greetings…

I’m programming a simple Asteroids like game. It has a main scene, another scene for the player ship, and now I added a scene for the first enemy.

The main scene has an instance of the player scene and will sure have many instances of the enemy scene (many enemies on screen). How can I get the value of the player position and other variables and pass them to the enemy scene?

Thanks in advance.

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:bust_in_silhouette: Reply From: kidscancode

When the Player scene is instanced in Main, it becomes part of the tree and you treat it like any other node. To get the player’s position you would use

$Player.position

or

get_node("Player").position

Both are equivalent, $<node_name> is a shorthand for using get_node().

I’m aware of the get_node() and $… But how can I get the value of the ship values from INSIDE the enemy scene? Both are not in the same scene.

What I want is something like this (at the “enemy” scene):

func _process(delta):
          if playerposition (variables and/or attributes at the "ship" scene) < enemy.position:
                    enemy.position -= 10 * delta
              if playerposition (variables and/or attributes at the "ship" scene) > enemy.position:
                    enemy.position += 10 * delta

My question is how to get the attributes inside the “ship” scene from inside the “enemy” scene.

Leandro | 2018-11-28 17:08

Actually, they’re all in the same scene - Main. At runtime, there is only one scene. It really doesn’t matter whether the nodes in it are instances or not. So if your main scene looks like this:

Main
  -- Player
  -- Enemy

Then there are many different ways to pass the information. A couple of examples:

  1. From the Enemy, use get_node("../Player").position
  2. From Main, pass the player’s position to the Enemy: $Enemy.target_position = $Player.position
  3. When the enemy is instanced, give it a reference to the player: $Enemy.target = $Player, then you can reference it in the enemy script whenever you need it.

Pros/cons:

  1. This is simple, but less optimal. It is usually a bad idea to hardcode the tree hierarchy in the script, as it will break if you move things around.
  2. In this scenario, you’d have to continually update that variable from main.
  3. This is probably the best option. Since the enemy has a reference to the player, you can have it respond to more than just position. Perhaps it does something if the player’s health is low, or if the player has a powerup, etc.

kidscancode | 2018-11-28 17:18

  1. When the enemy is instanced, give it a reference to the player:
    $Enemy.target = $Player, then you can reference it in the enemy script
    whenever you need it.

Thanks… Where can I get more information about this reference stuff?

Leandro | 2018-11-28 17:42

By “reference”, I mean you can refer to it. If the Enemy’s target variable points to the Player node, then any time you like in the Enemy script you can do things like:

if position.distance_to(target.position) < 10:
    # do something

You can reference any property or function of the Player using target.<name>

By the way, have you gone through the official tutorial? A lot of this kind of thing is covered in the Step By Step section.

kidscancode | 2018-11-28 18:01

Mea culpa. There’s a lot I still did not see from the official tutorial. I’ll check it now.

Thanks!

Leandro | 2018-11-28 23:51