Input examples

Introduction

In this tutorial, you'll learn how to use Redot's InputEvent system to capture player input. There are many different types of input your game may use - keyboard, gamepad, mouse, etc. - and many different ways to turn those inputs into actions in your game. This document will show you some of the most common scenarios, which you can use as starting points for your own projects.

Note

For a detailed overview of how Redot's input event system works, see Using InputEvent.

Events versus polling

Sometimes you want your game to respond to a certain input event - pressing the "jump" button, for example. For other situations, you might want something to happen as long as a key is pressed, such as movement. In the first case, you can use the _input() function, which will be called whenever an input event occurs. In the second case, Redot provides the Input singleton, which you can use to query the state of an input.

Examples:

GDScriptC#

func _input(event):
    if event.is_action_pressed("jump"):
        jump()


func _physics_process(delta):
    if Input.is_action_pressed("move_right"):
        # Move as long as the key/button is pressed.
        position.x += speed * delta

This gives you the flexibility to mix-and-match the type of input processing you do.

For the remainder of this tutorial, we'll focus on capturing individual events in _input().

Input events

Input events are objects that inherit from InputEvent. Depending on the event type, the object will contain specific properties related to that event. To see what events actually look like, add a Node and attach the following script:

GDScriptC#

extends Node


func _input(event):
    print(event.as_text())

As you press keys, move the mouse, and perform other inputs, you'll see each event scroll by in the output window. Here's an example of the output:

A
InputEventMouseMotion : button_mask=0, position=(108, 108), relative=(26, 1), speed=(164.152496, 159.119843), pressure=(0), tilt=(0, 0)
InputEventMouseButton : button_index=BUTTON_LEFT, pressed=true, position=(108, 107), button_mask=1, doubleclick=false
InputEventMouseButton : button_index=BUTTON_LEFT, pressed=false, position=(108, 107), button_mask=0, doubleclick=false
S
F
Alt
InputEventMouseMotion : button_mask=0, position=(108, 107), relative=(0, -1), speed=(164.152496, 159.119843), pressure=(0), tilt=(0, 0)

As you can see, the results are very different for the different types of input. Key events are even printed as their key symbols. For example, let's consider InputEventMouseButton. It inherits from the following classes:

• InputEvent - the base class for all input events

• InputEventWithModifiers - adds the ability to check if modifiers are pressed, such as Shift or Alt.

• InputEventMouse - adds mouse event properties, such as position

• InputEventMouseButton - contains the index of the button that was pressed, whether it was a double-click, etc.

Tip

It's a good idea to keep the class reference open while you're working with events so you can check the event type's available properties and methods.

You can encounter errors if you try to access a property on an input type that doesn't contain it - calling position on InputEventKey for example. To avoid this, make sure to test the event type first:

GDScriptC#

func _input(event):
    if event is InputEventMouseButton:
        print("mouse button event at ", event.position)

InputMap

The InputMap is the most flexible way to handle a variety of inputs. You use this by creating named input actions, to which you can assign any number of input events, such as keypresses or mouse clicks. A new Redot project includes a number of default actions already defined. To see them, and to add your own, open Project -> Project Settings and select the InputMap tab:

Capturing actions

Once you've defined your actions, you can process them in your scripts using is_action_pressed() and is_action_released() by passing the name of the action you're looking for:

GDScriptC#

func _input(event):
    if event.is_action_pressed("my_action"):
        print("my_action occurred!")

Keyboard events

Keyboard events are captured in InputEventKey. While it's recommended to use input actions instead, there may be cases where you want to specifically look at key events. For this example, let's check for the T:

GDScriptC#

func _input(event):
    if event is InputEventKey and event.pressed:
        if event.scancode == KEY_T:
            print("T was pressed")

Tip

See @GlobalScope_KeyList for a list of scancode constants.

Warning

Due to keyboard ghosting, not all key inputs may be registered at a given time if you press too many keys at once. Due to their location on the keyboard, certain keys are more prone to ghosting than others. Some keyboards feature antighosting at a hardware level, but this feature is generally not present on low-end keyboards and laptop keyboards.

As a result, it's recommended to use a default keyboard layout that is designed to work well on a keyboard without antighosting. See this Gamedev Stack Exchange question for more information.

Keyboard modifiers

Modifier properties are inherited from InputEventWithModifiers. This allows you to check for modifier combinations using boolean properties. Let's imagine you want one thing to happen when the T is pressed, but something different when it's Shift + T:

GDScriptC#

func _input(event):
    if event is InputEventKey and event.pressed:
        if event.scancode == KEY_T:
            if event.shift:
                print("Shift+T was pressed")
            else:
                print("T was pressed")

Tip

See @GlobalScope_KeyList for a list of scancode constants.

Mouse events

Mouse events stem from the InputEventMouse class, and are separated into two types: InputEventMouseButton and InputEventMouseMotion. Note that this means that all mouse events will contain a position property.

Mouse buttons

Capturing mouse buttons is very similar to handling key events. @GlobalScope_ButtonList contains a list of BUTTON_* constants for each possible button, which will be reported in the event's button_index property. Note that the scrollwheel also counts as a button - two buttons, to be precise, with both BUTTON_WHEEL_UP and BUTTON_WHEEL_DOWN being separate events.

GDScriptC#

func _input(event):
    if event is InputEventMouseButton:
        if event.button_index == BUTTON_LEFT and event.pressed:
            print("Left button was clicked at ", event.position)
        if event.button_index == BUTTON_WHEEL_UP and event.pressed:
            print("Wheel up")

Mouse motion

InputEventMouseMotion events occur whenever the mouse moves. You can find the move's distance with the relative property.

Here's an example using mouse events to drag-and-drop a Sprite node:

GDScriptC#

extends Node


var dragging = false
var click_radius = 32 # Size of the sprite.


func _input(event):
    if event is InputEventMouseButton and event.button_index == BUTTON_LEFT:
        if (event.position - $Sprite.position).length() < click_radius:
            # Start dragging if the click is on the sprite.
            if not dragging and event.pressed:
                dragging = true
        # Stop dragging if the button is released.
        if dragging and not event.pressed:
            dragging = false

    if event is InputEventMouseMotion and dragging:
        # While dragging, move the sprite with the mouse.
        $Sprite.position = event.position

Touch events

If you are using a touchscreen device, you can generate touch events. InputEventScreenTouch is equivalent to a mouse click event, and InputEventScreenDrag works much the same as mouse motion.

Tip

To test your touch events on a non-touchscreen device, open Project Settings and go to the "Input Devices/Pointing" section. Enable "Emulate Touch From Mouse" and your project will interpret mouse clicks and motion as touch events.