8.5 KiB
Input examples
Introduction
In this tutorial, you'll learn how to use Pandemonium'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 Pandemonium's input event system works,
see doc_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, Pandemonium provides the Input
singleton, which you can use to query the state of an input.
Examples:
gdscript GDScript
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:
gdscript GDScript
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 eventsInputEventWithModifiers- adds the ability to check if modifiers are pressed, such as :kbd:Shiftor :kbd:Alt.InputEventMouse- adds mouse event properties, such aspositionInputEventMouseButton- 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:
gdscript GDScript
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 Pandemonium 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:
gdscript GDScript
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 :kbd:T:
gdscript GDScript
func _input(event):
if event is InputEventKey and event.pressed:
if event.scancode == KEY_T:
print("T was pressed")
Tip:
See @GlobalScope_KeyList ( enum_@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 ( https://gamedev.stackexchange.com/a/109002 )`
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 :kbd:T is pressed, but something
different when it's :kbd:Shift + T:
gdscript GDScript
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 ( enum_@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 ( enum_@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.
gdscript GDScript
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:
gdscript GDScript
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.