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可複寫函式¶

Godot 的 Node 類提供了虛函式，你可以通過覆蓋虛函式來在每影格或發生特定事件時更新節點，比如進入場景樹時。

本文件中會展示你會經常用到的那些。

也參考

這些函式在引擎內部會依賴 Godot 的底層通知系統。要瞭解相關學習，請參閱 Godot 通知。

Two functions allow you to initialize and get nodes besides the class's constructor: _enter_tree() and _ready().

節點進入場景樹時就會被啟動，引擎會呼叫其 _enter_tree() 方法。該節點的子項可能還不是活動場景的一部分。因為你可以從場景樹中移除節點然後重新新增，在一個節點的生命期中，這個函式可能會被呼叫多次。

Most of the time, you'll use _ready() instead. This function is called only once in a node's lifetime, after _enter_tree(). _ready() ensures that all children have entered the scene tree first, so you can safely call get_node() on them.

也參考

要學習更多關於節點引用的知識，請閱讀節點與資源。

Another related callback is _exit_tree(), which the engine calls every time a node is about to exit the scene tree. This can be when you call Node.remove_child() or when you free a node.

# Called every time the node enters the scene tree.
func _enter_tree():
    pass

# Called when both the node and its children have entered the scene tree.
func _ready():
    pass

# Called when the node is about to leave the scene tree, after all its
# children received the _exit_tree() callback.
func _exit_tree():
    pass

// Called every time the node enters the scene tree.
public override void _EnterTree()
{
    base._EnterTree();
}

// Called when both the node and its children have entered the scene tree.
public override void _Ready()
{
    base._Ready();
}

// Called when the node is about to leave the scene tree, after all its
// children.
public override void _ExitTree()
{
    base._ExitTree();
}

虛函式 _process() 和 _physics_process() 可以分別用來對節點進行每影格和每物理影格的更新。要瞭解更多資訊，請閱讀專門的文件：空閒處理與物理處理。

# Called every frame.
func _process(delta):
    pass

# Called every physics frame.
func _physics_process(delta):
    pass

public override void _Process(double delta)
{
    // Called every frame.
    base._Process(delta);
}

public override void _PhysicsProcess(double delta)
{
    // Called every physics frame.
    base._PhysicsProcess(delta);
}

Two more essential built-in node callback functions are Node._unhandled_input() and Node._input(), which you use to both receive and process individual input events. The _unhandled_input() method receives every key press, mouse click, etc. that have not been handled already in an _input() callback or in a user interface component. You want to use it for gameplay input in general. The _input() callback allows you to intercept and process input events before _unhandled_input() gets them.

要學習更多關於 Godot 中輸入的內容，請參閱:ref:輸入章節 <toc-learn-features-inputs>。

# Called once for every event.
func _unhandled_input(event):
    pass

# Called once for every event before _unhandled_input(), allowing you to
# consume some events.
func _input(event):
    pass

// Called once for every event.
public override void _UnhandledInput(InputEvent @event)
{
    base._UnhandledInput(@event);
}

// Called once for every event before _UnhandledInput(), allowing you to
// consume some events.
public override void _Input(InputEvent @event)
{
    base._Input(@event);
}

There are some more overridable functions like Node._get_configuration_warnings(). Specialized node types provide more callbacks like CanvasItem._draw() to draw programmatically or Control._gui_input() to handle clicks and input on UI elements.