#  Sierpinski's Triangle

link graphics

$define Width  400
$define Height 400

$define X1 0			# lower-left vertex
$define Y1 Height

$define X2 (Width / 2)		# top vertex
$define Y2 0

$define X3 Width		# lower-right vertex
$define Y3 Height

procedure main()
   local x, y

   WOpen("size=" || Width || "," || Height) | stop("*** cannot open window")

   x := Width / 2		# current point
   y := Height / 2

   until WQuit() do {		# loop until interrupted
      case ?3 of {		# pick corner randomly
         1:  {
            x := (x + X1) / 2	# move halfway to corner
            y := (y + Y1) / 2
            }
         2:  {
            x := (x + X2) / 2	# move halfway to corner
            y := (y + Y2) / 2
            }
         3:  {
            x := (x + X3) / 2	# move halfway to corner
            y := (y + Y3) / 2
            }
         }
      DrawPoint(x, y)		# mark new location
      }

end