Baton

Baton is an input library for LÖVE that bridges the gap between keyboard and joystick controls and allows you to easily define and change controls on the fly.

local baton = require 'baton'

local input = baton.new {
  controls = {
    left = {'key:left', 'axis:leftx-', 'button:dpleft'},
    right = {'key:right', 'axis:leftx+', 'button:dpright'},
    up = {'key:up', 'axis:lefty-', 'button:dpup'},
    down = {'key:down', 'axis:lefty+', 'button:dpdown'},
    action = {'key:x', 'button:a'},
  },
  pairs = {
    move = {'left', 'right', 'up', 'down'}
  },
  joystick = love.joystick.getJoysticks()[1],
}

function love.update(dt)
  input:update()

  local x, y = input:get 'move'
  playerShip:move(x*100, y*100)
  if input:pressed 'action' then
    playerShip:shoot()
  end
end

Installation

To use Baton, place baton.lua in your project, and then add this code to your main.lua:

baton = require 'baton' -- if your baton.lua is in the root directory
baton = require 'path.to.baton' -- if it's in subfolders

Usage

Defining controls

Controls are defined using a table. Each key should be the name of a control, and each value should be another table. This table contains strings defining what sources should be mapped to the control. For example, this table

controls = {
  left = {'key:left', 'axis:leftx-'}
  shoot = {'key:x', 'button:a'}
}

will create a control called "left" that responds to the left arrow key and pushing the left analog stick on the controller to the left, and a control called "shoot" that responds to the X key on the keyboard and the A button on the gamepad.

Sources are strings with the following format:

'[input type]:[input source]'

Here are the different input types and the sources that can be associated with them:

Type	Description	Source
key	A keyboard key.	Any LÖVE KeyConstant
sc	A scancode.	Any LÖVE KeyConstant
mouse	A mouse button.	A number representing a mouse button (see love.mouse.isDown)
axis	A joystick or gamepad axis.	Either a number representing a joystick axis or a LÖVE GamepadAxis. Add a '+' or '-' on the end to denote the direction to detect.
button	A joystick or gamepad button.	Either a number repesenting a joystick button or a LÖVE GamepadButton
hat	A joystick hat.	A number representing a joystick hat and a JoystickHat. For example '1r' corresponds to the 1st hat pushed right.

Defining axis pairs

Baton allows you to define axis pairs, which group four controls under a single name. This is perfect for analog sticks, arrow keys, etc., as it allows you to get x and y components quickly. Each pair is defined by a table with the names of the four controls (in the order left, right, up, down).

pairs = {
  move = {'moveLeft', 'moveRight', 'moveUp', 'moveDown'},
  aim = {'aimLeft', 'aimRight', 'aimUp', 'aimDown'},
}

Players

Players are the objects that monitor and manage inputs.

Creating players

To create a player, use baton.new:

player = baton.new(config)

config is a table containing the following values:

• controls - a table of controls
• pairs - a table of axis pairs (optional)
• joystick - a LÖVE joystick (returned from love.joystick.getJoysticks). The joystick argument is optional; if it's not specified, or if the joystick becomes unavailable later, the player object will just ignore controller inputs.
• deadzone - a number from 0-1 representing the minimum value axes have to cross to be detected (optional)
• squareDeadzone (bool) - whether to use square deadzones for axis pairs or not (optional)

Updating players

You should update each player each frame by calling this function:

player:update()

Getting the value of controls

To get the value of a control, use:

value = player:get(control)

For example, for the controls defined above, we could get the value of the "left" control by doing

left = player:get 'left'

player:get always returns a number between 0 and 1, and as such, it is most applicable to controls that act as axes, such as movement controls. To get the value of a control without applying the deadzone, use player:getRaw.

Getting the value of axis pairs

player.get can also get the x and y components of an axis pair.

x, y = player:get(pair)

In this case, x and y are numbers between -1 and 1. The length of the vector x, y is capped to 1. player.getRaw will return the value of axis pairs without deadzone applied.

Getting down, pressed, and released states

To see whether a control is currently "held down", use:

down = player:down(control)

player:down returns true if the value of the control is greater than the deadzone, and false if not.

pressed = player:pressed(control)

player:pressed return true if the control was pressed this frame, and false if not.

released = player:released(control)

player:released return true if the control was released this frame, and false if not.

These functions are most applicable for controls that act as buttons, such as a shoot button. That being said, they can be used for any control, which is useful if you want to, for example, use a movement control as a discrete button press to operate a menu.

Updating the configuration

The controls table, pairs table, joystick, deadzone, and squareDeadzone can all be accessed via player.config. Any of the values can be changed, and the player's behavior will be updated automatically. Note, however, that new controls and pairs cannot be added after the player is created, and controls and pairs should not be removed entirely (if you want to disable a control, you can set it to an empty table, removing all of its sources).

Getting the active input device

At any time, only the keyboard/mouse sources or the josytick sources for a player will be active. A device will be considered active if any of the sources for that device exceed the deadzone. The keyboard and mouse will always take precedence over the joystick.

You can call player:getActiveDevice() to see which input device is currently active. It will return either 'kbm' (keyboard/mouse) or 'joy' (joystick) (or 'none' if no sources have been used yet). This is useful if you need to change what you display on screen based on the controls the player is using (such as instructions).

Contributing

This library is still fairly young, so feel free to take it for a spin and suggest additions and changes (especially if you try making a multiplayer game with it!). Issues and pull requests are always welcome. To run the test, run love . in the baton folder.