# Main Command: Go
# Sierpinski_Curve by Guy Walker
# www.logoarts.co.uk

to new
  # set default screen, pen and turtle 
  ResetAll SetScreenSize [400 400] HideTurtle 
  SetSC Black SetPC Green SetPS 1 PenUp 
end

to sier
  Make "Corner 1+Random 3    # choose random corner
  Make "CornerPos Item :Corner [ [190 -180] [-190 -180] [0 160] ]
  SetH Towards :CornerPos    # turn to face corner
  Forward (Distance :CornerPos)/2   # move half way towards corner
  PenDown Forward 0 PenUp   # plot pixel
  SetPC Run Item :Corner [Green Yellow Magenta]
end

to go
  New SetPC Black
  Repeat 40000 [Sier]   # repeat 40000 times
end