# Recipe 48: Draw the grey effect

def greyEffect():

  pic = makeEmptyPicture(400,100)

  # First, 100 columns of 100-grey
  grey = makeColor(100,100,100)
  for x in range(1,100):
    for y in range(1,100):
      setColor(getPixel(pic,x,y),grey)

  # Second, 100 columns of increasing greyness
  greyLevel = 100
  for x in range(100,200):
    grey = makeColor(greyLevel, greyLevel, \
                                  greyLevel)
    for y in range(1,100):
      setColor(getPixel(pic,x,y),grey)
    greyLevel = greyLevel + 1

  # Third, 100 columns of increasing greyness, from 0
  greyLevel = 0
  for x in range(200,300):
    grey = makeColor(greyLevel, \
                            greyLevel, greyLevel)
    for y in range(1,100):
      setColor(getPixel(pic,x,y),grey)
    greyLevel = greyLevel + 1

  # Finally, 100 columns of 100-grey
  grey = makeColor(100,100,100)
  for x in range(300,400):
    for y in range(1,100):
      setColor(getPixel(pic,x,y),grey)

  return pic