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Input

Learn how to capture input from mice, keyboards, and game controllers

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It’s easy to capture input from just about anything. Let’s learn how to grab input events from the mouse, keyboard, and game controllers.

Keyboard

There are three types of keyboard events captured by the window: when a key is pressed down, a key is being held down, and a key is released.

on :key do |event|
  # All keyboard interaction
  puts event
end
on :key_down do |event|
  # A key was pressed
  puts event.key
end
on :key_held do |event|
  # A key is being held down
  puts event.key
end
on :key_up do |event|
  # A key was released
  puts event.key
end

Mouse

The coordinates of the mouse can be read like so:

# Using the DSL
get :mouse_x
get :mouse_y

# Or using the `Window` class
Window.mouse_x
Window.mouse_y

Capture all mouse events:

on :mouse do |event|
  # A mouse event occurred
  puts event
end

Capture events when a mouse button is pressed down:

on :mouse_down do |event|
  # x and y coordinates of the mouse button event
  puts event.x, event.y

  # Read the button event
  case event.button
  when :left
    # Left mouse button pressed down
  when :middle
    # Middle mouse button pressed down
  when :right
    # Right mouse button pressed down
  end
end

Capture events when a mouse button is released:

on :mouse_up do |event|
  # x and y coordinates of the mouse button event
  puts event.x, event.y

  # Read the button event
  case event.button
  when :left
    # Left mouse button released
  when :middle
    # Middle mouse button released
  when :right
    # Right mouse button released
  end
end

Capture events when the mouse is scrolled:

on :mouse_scroll do |event|
  # Change in the x and y coordinates
  puts event.delta_x
  puts event.delta_y
end

Capture events when the mouse is moved:

on :mouse_move do |event|
  # Change in the x and y coordinates
  puts event.delta_x
  puts event.delta_y

  # Position of the mouse
  puts event.x, event.y
end

Controllers

All game controllers are automatically detected, added, and removed. There are two types of events captured by the window: axis motion and button presses. Buttons and axes are mapped to a generic Xbox controller layout.

To capture all controller events, use:

on :controller do |event|
  # A controller event occurred
  puts event
end

To capture only analog stick axis motion, use:

on :controller_axis do |event|
  case event.axis
  when :left_x
    # Left analog stick x axis
    puts event.value
  when :left_y
    # Left analog stick y axis
    puts event.value
  when :right_x
    # Right analog stick x axis
    puts event.value
  when :right_y
    # Right analog stick y axis
    puts event.value
  when :trigger_left
    # Left trigger axis
    puts event.value
  when :trigger_right
    # Right trigger axis
    puts event.value
  end
end

To capture when a button is pressed down, use:

on :controller_button_down do |event|
  # A controller button was pressed
  puts event.button
end

To capture when a button is released, use:

on :controller_button_up do |event|
  # A controller button was released
  puts event.button
end

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