module Cache

  #--------------------------------------------------------------------------
  # ● saveのビットマップを作成
  #--------------------------------------------------------------------------
  def self.make_Cache_lamp_bitmap(id,min_r , reduce_degree,color1,color2)
    @cache ||= {}

    sid = sprintf("lamp%s" , id)
    r = change_radius(id, min_r , reduce_degree) 
    bmp_size = 2 * r + 6
    bitmap = Bitmap.new(bmp_size  , bmp_size) 
    make_dark_lamp_bmp(bitmap, bmp_size / 2 , bmp_size / 2 , r , color1,color2)    
    @cache[sid] = bitmap unless include?(sid)
    
  end 
  #--------------------------------------------------------------------------
  # ● saveのビットマップを取得
  #--------------------------------------------------------------------------
  def self.load_Cache_lamp_bitmap(id)
    @cache ||= {}
    sid = sprintf("lamp%s" , id)  
    @cache[sid] 
    
  end   
  
  
  
  def self.change_radius(id, min_r , reduce_degree)
    return min_r + reduce_degree * id

  end  
  
  def self.make_dark_lamp_bmp(bmp,x0,y0,r,color1,color2 = nil)
    

    for x in  0..bmp.width
      for y in 0..bmp.height
        make_dark_lamp_bmp_pt(bmp,x0,y0,x,y,r,color1,color2)
      end  
    end  
  
  end    
  
  
  def self.make_dark_lamp_bmp_pt(bmp,x0 , y0 , x , y , r , color1 , color2 = nil)
    dx = x - x0
    dy = y - y0
    if dx ** 2 + dy ** 2 >= r ** 2
      bmp.set_pixel(x, y, color1)
    elsif dx ** 2 + dy ** 2 >= (r / 2) ** 2
      paint_circle(bmp,x0 , y0 , x , y , r  , color1)
    else  
      return
      
    end  
    
  end  
  
  def self.paint_circle(bmp,x0 , y0 , x , y , r  , color1)
    dx = x - x0
    dy = y - y0    
    halfr = 1.0 * r / 2 
    a = (255 * 4) / (3.0 * r ** 2)
    alp = [a * ((dx ** 2 + dy ** 2) - (r ** 2 / 4.0) ), 255].min
    newcolor = Color.new 
    newcolor.set(color1) 
    newcolor.alpha = alp
#~     color1.alpha = d 
    bmp.set_pixel(x, y, newcolor) 
    
  end  
end