-- Draw sub and add image

function love.load()
  bgimg = love.graphics.newImage("bg.jpg")
  subimg = love.graphics.newImage("sub.png")
  addimg = love.graphics.newImage("add.png")
end

function love.update(dt)
end

function love.draw()
  -- canvas clear
  love.graphics.clear(0, 0, 0, 1)

  -- draw bg
  love.graphics.setColor(1, 1, 1, 1)
  love.graphics.setBlendMode("alpha")
  love.graphics.draw(bgimg, 0, 0)
  
  -- draw sub image
  love.graphics.setBlendMode("subtract")
  love.graphics.draw(subimg, 0, 0)

  -- draw add image
  love.graphics.setBlendMode("add")
  love.graphics.draw(addimg, 0, 0)

  -- draw text
  love.graphics.setBlendMode("alpha")
  love.graphics.print("ESC to exit.", 8, 4)
end

function love.keypressed(key, scancode, isrepeat)
  if key == "escape" then
    love.event.quit()
  end
end