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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 Redot project's game loop. It is inherited by SceneTree, which is the default game loop implementation used in Redot 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. redot -s my_loop.gd) or the ProjectSettings.application/run/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 Redot;

[GlobalClass]
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}");
    }
}

Methods

void	_finalize() virtual
void	_initialize() virtual
bool	_physics_process(delta: float) virtual
bool	_process(delta: float) virtual

Signals

on_request_permissions_result(permission: String, granted: bool) 🔗

Emitted when a user responds to a permission request.

Constants

NOTIFICATION_OS_MEMORY_WARNING = 2009 🔗

Notification received from the OS when the application is exceeding its allocated memory.

Specific to the iOS platform.

NOTIFICATION_TRANSLATION_CHANGED = 2010 🔗

Notification received when translations may have changed. Can be triggered by the user changing the locale. Can be used to respond to language changes, for example to change the UI strings on the fly. Useful when working with the built-in translation support, like Object.tr.

NOTIFICATION_WM_ABOUT = 2011 🔗

Notification received from the OS when a request for "About" information is sent.

Specific to the macOS platform.

NOTIFICATION_CRASH = 2012 🔗

Notification received from Redot's crash handler when the engine is about to crash.

Implemented on desktop platforms if the crash handler is enabled.

NOTIFICATION_OS_IME_UPDATE = 2013 🔗

Notification received from the OS when an update of the Input Method Engine occurs (e.g. change of IME cursor position or composition string).

Specific to the macOS platform.

NOTIFICATION_APPLICATION_RESUMED = 2014 🔗

Notification received from the OS when the application is resumed.

Specific to the Android and iOS platforms.

NOTIFICATION_APPLICATION_PAUSED = 2015 🔗

Notification received from the OS when the application is paused.

Specific to the Android and iOS platforms.

Note: On iOS, you only have approximately 5 seconds to finish a task started by this signal. If you go over this allotment, iOS will kill the app instead of pausing it.

NOTIFICATION_APPLICATION_FOCUS_IN = 2016 🔗

Notification received from the OS when the application is focused, i.e. when changing the focus from the OS desktop or a thirdparty application to any open window of the Redot instance.

Implemented on desktop and mobile platforms.

NOTIFICATION_APPLICATION_FOCUS_OUT = 2017 🔗

Notification received from the OS when the application is defocused, i.e. when changing the focus from any open window of the Redot instance to the OS desktop or a thirdparty application.

Implemented on desktop and mobile platforms.

NOTIFICATION_TEXT_SERVER_CHANGED = 2018 🔗

Notification received when text server is changed.

Method Descriptions

void _finalize() virtual 🔗

Called before the program exits.

void _initialize() virtual 🔗

Called once during initialization.

bool _physics_process(delta: float) virtual 🔗

Called each physics frame with the time since the last physics frame as argument (delta, in seconds). Equivalent to Node._physics_process.

If implemented, the method must return a boolean value. true ends the main loop, while false lets it proceed to the next frame.

bool _process(delta: float) virtual 🔗

Called each process (idle) frame with the time since the last process frame as argument (in seconds). Equivalent to Node._process.

If implemented, the method must return a boolean value. true ends the main loop, while false lets it proceed to the next frame.