class Game_Picture
  #--------------------------------------------------------------------------
  # ● オブジェクト初期化
  #--------------------------------------------------------------------------
  alias tako3422initialize initialize
  def initialize(number)
    tako3422initialize(number)
    @co_duration = 0
  end  
  
  def co_duration
    @co_duration = 0 unless @co_duration 
    @co_duration
  end  
  
  #--------------------------------------------------------------------------
  # ● フレーム更新
  #--------------------------------------------------------------------------
  alias tako43rupdate update
  def update
    tako43rupdate
    update_change_opacity
  end  
  #--------------------------------------------------------------------------
  # ● 画像のフェードアウト
  #--------------------------------------------------------------------------
  def start_change_opacity(duration , target_opacity)
    @co_duration0 = duration
    @co_duration = duration
    @co_start_opacity = @opacity
    @co_target_opacity = target_opacity
    @opacity = target_opacity if @co_duration == 0
  end  
  #--------------------------------------------------------------------------
  # ● opacityの更新
  #--------------------------------------------------------------------------
  def update_change_opacity
    @co_duration = 0 unless @co_duration 
    return if @co_duration == 0
    d = @co_duration
    d0 = @co_duration0
    sopc = @co_start_opacity 
    topc = @co_target_opacity
    @opacity = topc + (sopc - topc) * d / d0
    @co_duration -= 1
  end  
end