gamepad emulation of playdate crank

controller.lua

-- uses:
--   https://github.com/rxi/classic
--   https://github.com/rxi/lume
local Object = require 'classic'
local lume = require 'lume'

---@class Controller
local Controller = Object:extend()

local function getStickAngle(x, y)
  if math.abs(x) < .5 and math.abs(y) < .5 then
    return
  end
  return lume.angle(0, 0, x, y)
end

local AnalogStickCrank = Object:extend()

function AnalogStickCrank:new(joystick, axisx, axisy)
  self.joystick = joystick
  self.axisx = axisx
  self.axisy = axisy
  self.pos = 0
  self.rotation_this_frame = 0
  self.last_angle = nil
end

function AnalogStickCrank:update(dt)
  if not self.joystick then
    return
  end

  local x = self.joystick:getGamepadAxis(self.axisx)
  local y = self.joystick:getGamepadAxis(self.axisy)
  local angle = getStickAngle(x, y)
  if not angle then
    self.last_angle = angle
    self.rotation_this_frame = 0
    return
  end
  if not self.last_angle then
    self.last_angle = angle
  end

  self.rotation_this_frame = (angle - self.last_angle)
  self.pos = self.pos + self.rotation_this_frame
  self.last_angle = angle
end


function Controller:new(joystick)
  self.joystick = joystick
  self.crankl = AnalogStickCrank(self.joystick, 'leftx', 'lefty')
  self.crankr = AnalogStickCrank(self.joystick, 'rightx', 'righty')
end

function Controller:update(dt)
  self.crankl:update(dt)
  self.crankr:update(dt)
end


---@return Controller
return Controller

main.lua

Controller = require 'controller'

local lg = love.graphics

function love.load()
  _G.controller = Controller(love.joystick.getJoysticks()[1])
end

function love.update(dt)
  local rotation_this_frame = controller.crankr.rotation_this_frame or 0
end

function love.draw()
  lg.print(string.format("crank rotation: %0.3f", controller.crankr.pos), 5, 5)
end