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SDK Development Discussion
96

Cheat Codes

I've been working on adding some cheats to my game, figured I'd share the class here incase anyone else would like it.

local keys = {
  a = playdate.kButtonA,
  b = playdate.kButtonB,
  up = playdate.kButtonUp,
  down = playdate.kButtonDown,
  left = playdate.kButtonLeft,
  right = playdate.kButtonRight
}

class("CheatCode").extends()

function CheatCode:init(...)
  local seq = {}
  for _, key in ipairs({...}) do
    local v = keys[key]
    assert(v, "CheatCode: unknown key given => "..tostring(key))
    table.insert(seq, v)
  end

  self._seq = seq
  self.progress = 1
  self.completed = false
  self.run_once = true
  self:setTimerDelay(400)
end

function CheatCode:update()
  -- exit early if complete
  if self.run_once and self.completed then return end

  local _, pressed, _ = playdate.getButtonState()
  -- exit early if no button currently pressed
  if pressed == 0 then return end

  if pressed == self._seq[self.progress] then
    self.progress += 1
    self._timer:reset()

    if self.progress > #self._seq then
      self.completed = true
      if type(self.onComplete) == "function" then
        self.onComplete()
      end
    end
  else
    self:reset()
  end
end

function CheatCode:reset()
  self.progress = 1
  self._timer:reset()
  self._timer:pause()
end

function CheatCode:setTimerDelay(ms)
  if self._timer then
    self._timer:remove()
  end
  self._timer = playdate.timer.new(ms, function() self:reset() end)
  self._timer:pause()
  self._timer.discardOnCompletion = false
end

function CheatCode:nextIs(key)
  return keys[key] == self._seq[self.progress]
end

Using it is simple enough

-- initialize 
local cheat = CheatCode("up", "up", "down", "down", "left", "right", "left", "right", "b", "a")
cheat.onComplete = function() print("cheat") end

-- in update function
playdate.timer.updateTimers() -- uses timers so make sure you call this
cheat:update()

By default it'll only trigger the first time the sequence is called, can be changed by setting run_once to false

CheatCode:nextIs([key]) is a helper to allow you to avoid triggering other effects while the code is being entered. eg:

if not cheat:nextIs("a") then
    -- do something else
end
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