Nodes and scene instances¶

This guide explains how to get nodes, create nodes, add them as a child, and instantiate scenes from code.

Getting nodes¶

You can get a reference to a node by calling the Node.get_node() method. For this to work, the child node must be present in the scene tree. Getting it in the parent node's _ready() function guarantees that.

If, for example, you have a scene tree like this, and you want to get a reference to the Sprite and Camera2D nodes to access them in your script.

../../_images/nodes_and_scene_instances_player_scene_example.png

Для этого вы можете использовать следующий код.

var sprite
var camera2d

func _ready():
    sprite = get_node("Sprite")
    camera2d = get_node("Camera2D")

private Sprite _sprite;
private Camera2D _camera2d;

public override void _Ready()
{
    base._Ready();

    _sprite = GetNode<Sprite>("Sprite");
    _camera2d = GetNode<Camera2D>("Camera2D");
}

Note that you get nodes using their name, not their type. Above, "Sprite" and "Camera2D" are the nodes' names in the scene.

If you rename the Sprite node as Skin in the Scene dock, you have to change the line that gets the node to get_node("Skin") in the script.

Node paths¶

When getting a reference to a node, you're not limited to getting a direct child. The get_node() function supports paths, a bit like when working with a file browser. Add a slash to separate nodes.

Take the following example scene, with the script attached to the UserInterface node.

../../_images/nodes_and_scene_instances_ui_scene_example.png

Чтобы получить узел Tween, используйте следующий код.

var tween

func _ready():
    tween = get_node("ShieldBar/Tween")

private Tween _tween;

public override void _Ready()
{
    base._Ready();

    _tween = GetNode<Tween>("ShieldBar/Tween");
}

Примечание

As with file paths, you can use ".." to get a parent node. The best practice is to avoid doing that though not to break encapsulation. You can also start the path with a forward slash to make it absolute, in which case your topmost node would be "/root", the application's predefined root viewport.

Syntactic sugar¶

You can use two shorthands to shorten your code in GDScript. Firstly, putting the onready keyword before a member variable makes it initialize right before the _ready() callback.

onready var sprite = get_node("Sprite")

There is also a short notation for get_node(): the dollar sign, "$". You place it before the name or path of the node you want to get.

onready var sprite = $Sprite
onready var tween = $ShieldBar/Tween

Создание узлов¶

Чтобы создать узел из кода, вызовите его метод new(), как для любого другого типа данных, основанного на классе.

You can store the newly created node's reference in a variable and call add_child() to add it as a child of the node to which you attached the script.

var sprite

func _ready():
    var sprite = Sprite.new() # Create a new Sprite.
    add_child(sprite) # Add it as a child of this node.

private Sprite _sprite;

public override void _Ready()
{
    base._Ready();

    _sprite = new Sprite(); // Create a new Sprite.
    AddChild(_sprite); // Add it as a child of this node.
}

To delete a node and free it from memory, you can call its queue_free() method. Doing so queues the node for deletion at the end of the current frame after it has finished processing. At that point, the engine removes the node from the scene and frees the object in memory.

sprite.queue_free()

_sprite.QueueFree();

Before calling sprite.queue_free(), the remote scene tree looks like this.

After the engine freed the node, the remote scene tree doesn't display the sprite anymore.

You can alternatively call free() to immediately destroy the node. You should do this with care as any reference to it will instantly become null. We recommend using queue_free() unless you know what you're doing.

When you free a node, it also frees all its children. Thanks to this, to delete an entire branch of the scene tree, you only have to free the topmost parent node.

Инстанцирование сцен¶

Scenes are templates from which you can create as many reproductions as you'd like. This operation is called instancing, and doing it from code happens in two steps:

Загрузка сцены с жесткого диска.
Creating an instance of the loaded PackedScene resource.

var scene = load("res://MyScene.tscn")

var scene = GD.Load<PackedScene>("res://MyScene.tscn");

Preloading the scene can improve the user's experience as the load operation happens when the compiler reads the script and not at runtime. This feature is only available with GDScript.

var scene = preload("res://MyScene.tscn")

В этот момент scene является ресурсом упакованной сцены, а не узлом. Чтобы создать настоящий узел, необходимо вызвать PackedScene.instance(). Он возвращает дерево узлов, которые вы можете сделать дочерними по отношению к текущему узлу.

var instance = scene.instance()
add_child(instance)

var instance = scene.Instance();
AddChild(instance);

The advantage of this two-step process is you can keep a packed scene loaded and create new instances on the fly. For example, to quickly instance several enemies or bullets.