Yin Yang

- XLogo recursion

The famous yin yang symbol drawn in a recursive set of green and blue symbols.

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

To Yin :Size [:Parity 1]
  # yin shape drawn from centre (tp)
  # default parity of 1, use minus 1 for mirror image
  Make "Offset :Size/4     # global offset fill
  rArc 180 :Size/2 Back :Parity *:Size/4
  rArc 180 :Size/4 Back :Parity *:Size/2
  rArc 180 :Size/4 Back :Parity *:Size/4 Left 180

To YinYang :Size
  If :Size < 12 [Stop]
  Right 15 Repeat 2 [
    SetPC [0 192 192]
    Yin :Size Forward :Size/4
    If :Col = True [SetPC Aqua] [SetPC Leaf]
    Make "Col Not :Col
    Fill Wait :Size/6
    YinYang :Size/2
    Back :Size/4 Left 180] Left 15

To rArc :Angle :Radius
  # clockwise arc drawn relative to turtle heading
  Arc :Radius Heading :Angle+Heading Right :Angle

To Aqua
  Output [0 128 255]     # return aqua rgb color

To Leaf
  Output [0 255 128]     # return leaf rgb color

To Go
  New Make "Col True
  YinYang 384

Binary Switch
Yin Yang

Procedures blue
Variables pink
Comments green
Library gray