Logo Arts

To New
  # set default screen, pen and turtle values
  ResetAll SetScreenSize [400 400] HideTurtle
  SetSC Black SetPC Green SetPS 1 PenUp
End

To GridSq : Order : Side
  # draw tile at each column x row position
  LocalMake " Offset (1+ : Order )/2
  For (List " Col 1 : Order ) [
    For (List " Row 1 : Order ) [
      SetXY : Side *( : Col - : Offset ) : Side *( : Row - : Offset )
      Tile : Col : Row : Side ] ]
End

To Tile : Col : Row : Side
  If Even? ( : Col + : Row ) [Make " Hue 0 SetH 0] [Make " Hue 7 SetH 90]
  SetPC Blue
  Forward : Side /4 Right 90 Back : Side /4 Square ( : Side /2)-1 Fill
  Forward : Side /2 Left 90 Back : Side /2 Square ( : Side /2)-1 Fill
  Forward : Side /4 Right 90 Back : Side /4     # return to centre
  SetPC : Hue Circle ( : Side /2)-1 FillZone
  SetPC Abs ( : Hue -7) Circle ( : Side /2)-1 Wait 2
End

To Square : Side
  # square (side x side) drawn from centre (tp)
  Back : Side /2 Right 90 Back : Side /2 PenDown
  Repeat 4 [
    Forward : Side Left 90]
  PenUp Forward : Side /2 Left 90 Forward : Side /2     # r2c
End

To Even? : Num
  # return 'true' if Num even, else return 'false '
  If (Mod : Num 2)=0 [Output "True] [Output "False]
End

To Go : Order
  New SetSC White
  Make " Side Int (370/ : Order )
  Make " Board : Order * : Side     # whole number of squares
  SetPC Yellow Square : Board Fill
  SetPC Black Square : Board
  GridSq : Order : Side
End