# Main Command: Go
# Pebble2 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 Pebble :Wide :High
  # pebble shape drawn from centre (tp)
  LocalMake "Diff Abs :Wide-:High
  If :Wide > :High
    [LocalMake "Rad :High/2 LocalMake "Vert 0 LocalMake "Horiz :Diff]
    [LocalMake "Rad :Wide/2 LocalMake "Vert :Diff LocalMake "Horiz 0]
  PenUp Back :High/2 Right 90 Back :Horiz/2 PenDown
  Repeat 2 [
    Forward :Horiz LeftArc 90 :Rad Forward :Vert LeftArc 90 :Rad]
  PenUp Forward :Horiz/2 Left 90 Forward :High/2     # return to centre
End

To LeftArc :Angle :Radius
  # arc drawn relative to turtle position, angle & radius positive
  PenUp Right 90 Back :Radius Left :Angle
  Arc :Radius Heading Heading+:Angle
  Forward :Radius Left 90 PenDown
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 Go
  # pebble pillow 
  New Right 45
  For [Size 0.5 15.5] [
    Pebble 34*:Size 34*(16-:Size) ]
End