class Particle < Sprite
  # Min-Max movement speed
  MaxSpeed = 13
  MinSpeed = 5

  # Min-Max amplitude
  MaxAmp = 100
  MinAmp = 20

  def initialize
    super
    self.bitmap = Bitmap.new(32,32)
    self.bitmap.fill_rect(bitmap.rect, Color.new(255,255,255))
    self.ox = width/2
    @amplitude = 1
    @speed = 1
    @radian = 0.0
    restart
  end

  def restart
    @amplitude = MinAmp + rand(MaxAmp - MinAmp)
    @speed = rand(3) + 1 + rand
    @swing_speed = rand * 0.1
    @radian = rand + rand
    @xpos = rand(Graphics.width)
    @ypos = Graphics.height.to_f
    @method = [:sin, :cos].shuffle.first
    self.y = @ypos
    self.x = @xpos
    self.zoom_x = self.zoom_y = 1.0
  end

  def update
    super
    update_movement
    restart if self.zoom_x <= 0.0
  end

  def update_movement
    @radian += @swing_speed
    @ypos -= @speed
    self.x = Math.method(@method).call(@radian) * @amplitude + @xpos
    self.y = @ypos
    self.zoom_x -= 0.01
    self.zoom_y -= 0.01
  end

end

$sprite = Particle.new

loop do
  Graphics.update
  Input.update
  $sprite.update
end