# Main Command: Go 3
# Kanizsa Illusion 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 go :order
  New SetPW 2
  Make "Angle 180-(360/:Order)
  Repeat :Order [
    Forward 140 Dart :Angle 30 Arch 360-:Angle 30 
    Forward 10 Fill Back 10 
    SetPC Black Dart :Angle 30 SetPC Green
    Back 140 Left 180/:Order
    Forward 140 Dart :Angle Item :Order [0 0 78 56 44 32]
    Back 140 Left 180/:Order]
end

to dart :angle :size
  # dart drawn tp
  Right :Angle/2 PenDown Back :Size PenUp Forward :Size
  Left :Angle PenDown Back :Size PenUp Forward :Size Right :Angle/2
end

to arch :angle :radius
  # symmetrical arc drawn relative to turtle heading
  Arc :Radius Heading-:Angle/2 Heading+:Angle/2
end