# Main Command: Go
# Spinning Squares 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 spinsquare :side
  If :Side < 12 [Stop]
  SetPC Hue 1.4*:Side
  Square :Side
  Left 4
  SpinSquare :Side-8
end

To Hue :Theta
  # Output RGB hue list from angle :Theta
  Make "Red Round 127.5*(1+Sin :Theta)
  Make "Green Round 127.5*(1+Sin (:Theta+120))
  Make "Blue Round 127.5*(1+Sin (:Theta+240))
  Output (List :Red :Green :Blue)
End

to square :side
  # square (side x side) drawn from centre (tx)
  LocalMake "Half :Side/2 
  PenUp Back :Half Right 90 Back :Half
  PenDown Repeat 4 [ 
    Forward :Side Left 90] 
  PenUp Forward :Half Left 90 Forward :Half 
end

to go
  New Right 6 SpinSquare 340
end