gistfile1.rb

require 'gosu'
require 'texplay'
class GameWindow < Gosu::Window
  def initialize
    super 200, 200, false
    self.caption = "Scratch-off Sample"
    # below we set up the image resources that we'll use for the app
    # your base image that will be hidden under the grey layer
    @background_image = Gosu::Image.new(self, "a.jpg", true)
    # simply grey to cover our first image
    @grey = Gosu::Image.new(self, "grey.jpg", true)
    # small pointer or virtual coin to scratch-off the coating
    @pointer = Gosu::Image.new(self, "pointer.png", true)
    @pos_x = 0
    @pos_y = 0
  end
  
  def update
  	
  end
  
  def draw
    @background_image.draw(0, 0, 0)
    @pointer.draw(mouse_x, mouse_y, 0)
    a = mouse_x
    b = mouse_y
    @grey.paint{
        circle a+5, b+5, 10, 10, :mode => :clear, :fill => true
    }
    #@background_image.draw(0,0,0)
    @grey.draw(0, 0, 0)
  end
end

window = GameWindow.new
window.show