# Main Command: Go 160 220 5 3
# Ring Wave by Guy Walker
# www.logoarts.co.uk

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

To Init :Radius
  # global values for each curve
  GlobalMake "Steps 360
  GlobalMake "StepAngle 1
  GlobalMake "StepSize (2*Pi*:Radius)/(360/:StepAngle)
End

To Title :Titles
  # label up to 4 titles
  SetPC White Repeat Count :Titles [
    Home Right (RepCount*90) -135 Forward 262 SetH 0
    If X>0 [SetFontJustify [2 1]] [SetFontJustify [0 1]]
    Label Item RepCount :Titles]
End

To Go :Offset :Radius :Amp :Order
  New Title (List "RingWave [] List :Amp :Order List :Offset :Radius)
  Init :Radius SetPC Green
  PenUp SetXY 0 :Offset SetH 88 PenDown
  Forward :StepSize/2
  For (List "Angle 0 358) [
    Right :StepAngle + :Amp * Cos (:Order*:Angle)
    Forward :StepSize Wait 1]
  Right :StepAngle + :Amp * Cos (:Order*359)
  Forward :StepSize/2
End