Guide to the Godot game engine/Signals and methods
Many Godot users will say to you "signal up, call down" if you ask for tips with coding. Just what does this mean?
Select a node from the Scene dock. Press the "Node" tab next to the inspector. A list will appear. These are signals.
Create a new scene. Press User Interface. Save it as
Signal test.tscn. Add two nodes: a Button and a Label, both as children of the Control. Use the
Layout button to center the Button to the screen. Set the
Text property to
Press Me in the inspector.
Now add a script to the Control root node (the first one). Select the Button. Open the Node dock, and double click "button_up()". A popup will appear with your scene root (the Control node) selected. A text edit should say
_on_Button_button_up. Press "Connect".
This will create the code
func _on_Button_button_up(): pass # Replace with function body.
This function will be called when the signal
button_up is emitted. Add the code
print("You pressed me!") to the function. You may remove the
pass # Replace with function body. if you wish.
Run the scene by pressing F6, and grant that button's wish!
You can make your own signals with
signal <signal_name> <optional:(argument1: type, argument2: type, ect)> in GDScript. To emit it in a function:
emit_signal(<"signal_name">, <argument1>,<argument2 ect.>).
Just as important as signals, calling allows many things to happen. Add
$Label.text = "You pressed me!" to the function. This is actually setting a variable, but it's still considered calling, as setting a variable uses a setter function. More on those in another chapter.
$path is a short hand for the
get_node(path) function. The
Label is the path argument. This allows direct manipulation of the child node of that name.
These are called
$weapon/art.texture = preload("res://assets/weapons/upgraded_sword.png"), and can also be relative, like (called in
get_node looks like
For more, please see GDScript: Manipulating the SceneTree.
Signal up and call down Edit
It means, if you are calling methods on another node, use signals for calling parents (to decrease code complexity) and use methods when calling children (to increase readability and freedom).
What you have learned Edit
- How to get a child node.
- How to connect a signal.
- How to set a property of another node (With the ".". You can use it to call their functions too!)
- Getting started [ ]