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MainLoop¶

Inherits: Object

Inherited By: SceneTree

Abstract base class for the game's main loop.

Description¶

MainLoop is the abstract base class for a Godot project's game loop. It is inherited by SceneTree, which is the default game loop implementation used in Godot projects, though it is also possible to write and use one's own MainLoop subclass instead of the scene tree.

Upon the application start, a MainLoop implementation must be provided to the OS; otherwise, the application will exit. This happens automatically (and a SceneTree is created) unless a MainLoop Script is provided from the command line (with e.g. godot -s my_loop.gd or the "Main Loop Type" project setting is overwritten.

Here is an example script implementing a simple MainLoop:

class_name CustomMainLoop
extends MainLoop

var time_elapsed = 0

func _initialize():
    print("Initialized:")
    print("  Starting time: %s" % str(time_elapsed))

func _process(delta):
    time_elapsed += delta
    # Return true to end the main loop.
    return Input.get_mouse_button_mask() != 0 || Input.is_key_pressed(KEY_ESCAPE)

func _finalize():
    print("Finalized:")
    print("  End time: %s" % str(time_elapsed))

using Godot;

public partial class CustomMainLoop : MainLoop
{
    private double _timeElapsed = 0;

    public override void _Initialize()
    {
        GD.Print("Initialized:");
        GD.Print($"  Starting Time: {_timeElapsed}");
    }

    public override bool _Process(double delta)
    {
        _timeElapsed += delta;
        // Return true to end the main loop.
        return Input.GetMouseButtonMask() != 0 || Input.IsKeyPressed(Key.Escape);
    }

    private void _Finalize()
    {
        GD.Print("Finalized:");
        GD.Print($"  End Time: {_timeElapsed}");
    }
}