Flappy Pixel

# @name Flappy Pixel
# @desc Tiny one-button Flappy game for AWTRIX NG
# @version 0.1

import math

class FlappyPixel
  var bird_y
  var velocity

  var pipe_x
  var pipe_gap_y

  var score
  var highscore

  var running
  var game_over

  var last_ms
  var accumulator

  # Game tuning
  var frame_ms
  var gravity
  var flap_power

  def init()
    self.highscore = store.get("highscore")
    if self.highscore == nil
      self.highscore = 0
    end

    self.frame_ms = 100
    self.gravity = 1
    self.flap_power = -2

    self.reset_game()
  end

  def reset_game()
    self.bird_y = 3
    self.velocity = 0

    self.pipe_x = width() - 1
    self.new_pipe()

    self.score = 0

    self.running = false
    self.game_over = false

    self.last_ms = 0
    self.accumulator = 0
  end

  def new_pipe()
    # Gap starts at y 1..4.
    # Gap itself is 3 pixels high.
    self.pipe_gap_y = 1 + (math.rand() % 4)
  end

  def on_show()
    self.last_ms = now_ms()
  end

  def on_button(btn)
    if btn != "select"
      return
    end

    if self.game_over
      self.reset_game()
      self.running = true
      self.velocity = self.flap_power
      self.last_ms = now_ms()
      return
    end

    if !self.running
      self.running = true
    end

    self.velocity = self.flap_power
  end

  def update_game()
    if !self.running || self.game_over
      return
    end

    # Gravity
    self.velocity += self.gravity

    # Limit falling speed
    if self.velocity > 2
      self.velocity = 2
    end

    self.bird_y += self.velocity

    # Ceiling / floor collision
    if self.bird_y < 0 || self.bird_y > 7
      self.crash()
      return
    end

    # Move pipe left
    self.pipe_x -= 1

    # Bird lives at X = 5
    var bird_x = 5

    # Pipe is two pixels wide
    if bird_x >= self.pipe_x && bird_x <= self.pipe_x + 1
      if self.bird_y < self.pipe_gap_y ||
         self.bird_y > self.pipe_gap_y + 2
        self.crash()
        return
      end
    end

    # Pipe passed bird
    if self.pipe_x + 1 == bird_x - 1
      self.score += 1
    end

    # New pipe
    if self.pipe_x < -2
      self.pipe_x = width()
      self.new_pipe()
    end
  end

  def crash()
    self.game_over = true
    self.running = false

    if self.score > self.highscore
      self.highscore = self.score
      store.set("highscore", self.highscore)
    end
  end

  def draw_bird()
    var bird_x = 5

    # body
    pixel(bird_x, self.bird_y, 0xFFFF00)

    # little orange beak
    pixel(bird_x + 1, self.bird_y, 0xFF8800)

    # wing animation while flying
    if self.running
      if (now_ms() % 400) < 200
        if self.bird_y < 7
          pixel(bird_x - 1, self.bird_y + 1, 0xFFFFFF)
        end
      else
        if self.bird_y > 0
          pixel(bird_x - 1, self.bird_y - 1, 0xFFFFFF)
        end
      end
    end
  end

  def draw_pipe()
    var gap_start = self.pipe_gap_y
    var gap_end = self.pipe_gap_y + 2

    # Top pipe
    if gap_start > 0
      rect_fill(self.pipe_x, 0, 2, gap_start, 0x00CC44)
    end

    # Bottom pipe
    if gap_end < 7
      rect_fill(
        self.pipe_x,
        gap_end + 1,
        2,
        7 - gap_end,
        0x00CC44
      )
    end
  end

  def draw_idle()
    # Bird still visible
    self.draw_bird()

    # Small hint: blinking select indicator
    if (now_ms() % 1000) < 500
      pixel(15, 3, 0xFFFFFF)
      pixel(16, 3, 0xFFFFFF)
      pixel(17, 3, 0xFFFFFF)
    end
  end

  def draw_game_over()
    # Flash crash
    if (now_ms() % 500) < 250
      clear(0x300000)
    else
      clear()
    end

    font("small")

    text(1, 6, str(self.score), 0xFFFFFF)

    text(13, 6, "HI", 0x888888)
    text(22, 6, str(self.highscore), 0xFFFF00)
  end

  def draw()
    clear()

    if self.game_over
      self.draw_game_over()
      return
    end

    var current = now_ms()

    if self.last_ms == 0
      self.last_ms = current
    end

    var elapsed = current - self.last_ms
    self.last_ms = current

    # Avoid massive jump after app switching
    if elapsed > 500
      elapsed = 0
    end

    if self.running
      self.accumulator += elapsed

      while self.accumulator >= self.frame_ms
        self.update_game()
        self.accumulator -= self.frame_ms
      end
    end

    self.draw_pipe()

    if self.running
      self.draw_bird()
    else
      self.draw_idle()
    end
  end
end

return FlappyPixel()