# Main Command: Go
# Oscilloscope 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 spir :a
  Make "T 0 SetPC Black PenDown
  For [S 0 360 8] [SetPos XYCurve :A :S :T
    For [T 0 360 4] [SetPC AngCol :T SetPos XYCurve :A :S :T]
  Refresh Wash]      # put a wait in here if too fast
end

to xycurve :a :s :t
  Make "X 140*(Sin (90+:T))
  Make "Y 140*(Cos ((:A*(:T))+:S))+24*Sin (:T)
  Output List :X :Y
end

to angcol :t
  Make "Green Round 127*(1+Cos(:T+90)) 
  Output ( List 255 :Green 100 )
end

to go
  New Animation
  For [A 2 4] [Spir :A]
end