CrystGLFW::Joystick

A CrystGLFW::Joystick (or Joystick, for the purposes of this guide) represents a physical controller connected to the system. GLFW has 16 available joystick "slots", and a Joystick is simply a means of interacting with one of those slots. Internally Joystick is implemented as a Crystal Enum.

Joystick member names are derived from the names of the constants that represent them in the GLFW specification. The list of GLFW joysticks can be found here. Take the name of the constant, remove the "GLFWJOYSTICK" prefix and replace it with "Joystick::", and convert the rest to UpperCamelCase to get the name. For example:

GLFW_JOYSTICK_1 is represented in CrystGLFW as Joystick::One. GLFW_JOYSTICK_2 is Joystick::Two. GLFW_JOYSTICK_LAST is Joystick::Last.

And so on and so forth.

Joystick has one class method:

on_toggle_connection

on_toggle_connection defines the desired callback behavior when a Joystick is either connected or disconnected.

CrystGLFW::Joystick.on_toggle_connection do |event|
  if event.connected?
    puts "A joystick was just connected: #{event.joystick.name}"
  else
    puts "A joystick was just disconnected."
  end
end

on_toggle_connection yields a CrystGLFW::Event::JoystickToggleConnection to the block, and can be called from outside of a run block definition.

connected?

You can determine if a Joystick is currently connected using the connected? method:

joystick.connected? # => Bool

connected? returns true if the joystick is connected, and false if not.

name

You can retrieve the manufacturer's name for a Joystick using the name method:

puts joystick.name if joystick.connected? # => String

Make sure you check that the Joystick is actually connected first!

axes

You can retrieve the values of each axis on a Joystick using the axes method:

joystick.axes if joystick.connected? # => Slice(Float32)

The return value is an enumerable Slice of Float32, each between -1.0 and 1.0.

Make sure you check that the Joystick is actually connected first!

buttons

You can retrieve the state of each button on a Joystick using the buttons method:

joystick.buttons if joystick.connected? # => Array(Bool)

The return value is an array of Bool, where true means that the button is pressed, and false means that the button is released.

Make sure you check that the Joystick is actually connected first!

Checking Joysticks

Because Joystick is an Enum, question methods are available for each possible value of a given Joystick:

CrystGLFW::Joystick.on_toggle_connection do |event|
  if event.joystick.one?
    puts "The joystick in slot 1 was just connected or disconnected."
  end
end