knucklebones/states/state_main_menu.lua

function state_main_menu()
  local covering = {}
  local falling = {}
  local states

  local buttons = {
    {
      hover = false,
      label = "Play",
      box = { x = 120 - prn_len("Play") / 2, y = 100, w = prn_len("Play"), h = 10 },
      cb = function()
        trace("play")
        for i = 0, 240, 16 do
          for j = 0, 135, 16 do
            table.insert(covering, Die:new({
              value = math.random(1, 6),
              angle = 360,
              x = i,
              y = j,
              scale = 0
            }))
          end
        end
      end
    }
  }

  local function show_transition()
    -- slightly scale up the transition dice
    for i, die in ipairs(covering) do
      die.scale = die.scale + 0.03 / i * 80
      die.angle = die.angle * 0.90
      if die.scale > 1 then
        die.scale = 1
      end
      swap_color(12, 15)
      swap_color(0, 15)
      die:draw(-1)
    end
    if table.count(covering, function(d) return d.scale == 1 end) == #covering then
      state_manager:change_state(states.game, { covering = covering })
    end
  end

  local function falling_dice()
    local remove = {}
    for i, die in ipairs(falling) do
      die.y = die.y + 1
      die.angle = die.angle + die.rot_speed
      if die.y > 160 then
        table.insert(remove, i)
      end
    end
    for _, i in ipairs(remove) do
      table.remove(falling, i)
    end
  end

  local function draw_dice()
    for _, die in ipairs(falling) do
      swap_color(12, 15)
      swap_color(13, 15)
      swap_color(14, 15)
      die:draw()
      reset_colors(12)
    end
  end

  local function _enter(self, data)
    assert(data.states, "needs a states table")
    states = data.states
    covering = {}
  end

  local function update()
    -- random sign
    if math.random() < 0.05 then
      local sign = math.random() < 0.5 and -1 or 1
      -- Spawn a random die
      local die = Die:new({
        value = math.random(1, 6),
        x = math.random(240),
        y = -20,
        angle = math.random(10, 40),
        rot_speed = sign * math.random(6, 10) / 10,
      })
      table.insert(falling, die)
    end

    falling_dice()

    cls()
    draw_dice()

    -- prn_border("KNUCKLEBONES", 118, 10, 1, ALIGN.Center, 0, 2, 0)
    -- prn_border("KNUCKLEBONES", 122, 10, 2, ALIGN.Center, 0, 2, 1)
    prn_border("KNUCKLEBONES", 120, 10, 12, ALIGN.Center, 0, 2)

    local l = prn_len("A game of risk and reward")
    local x = 120 - l / 2
    local y = 50
    x = x + prn_border("A game of ", x, y, 13, ALIGN.Left, 0)
    x = x + prn_border_floaty("risk ", x, y + 5, 12, ALIGN.Left, 1, 1, 20)
    x = x + prn_border("and ", x, y, 13, ALIGN.Left, 0)
    x = x + prn_border_floaty("reward", x, y - 5, 12, ALIGN.Left, 8)
    print_border("Originally from \"The Cult of the Lamb\"", 104, 130, 14, 0, false, 1, true)
    local mx, my = mouse()

    for i, button in ipairs(buttons) do
      -- Print button
      local x, y, w, h = button.box.x, button.box.y, button.box.w, button.box.h
      local hover = mx >= x and mx <= x + w and my >= y and my <= y + h
      button.hover = hover
      local color = hover and 12 or 13
      -- rect(x, y, w, h, color)
      prn_border(button.label, x, y, color, ALIGN.Left, 0)

      -- Click button
      if hover and Input:mouse_pressed()
      then
        button.cb()
      end
    end

    if #covering > 0 then
      show_transition()
    end
  end
  return { update = update, _enter = _enter }
end