# Main Command: Go
# Lens Shapes 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 lens :angle :size
  # lens shape drawn from centre (tp)
  Make "Dist (:Size/2)/Tan :Angle/2
  Repeat 2 [
    Back :Dist Arch :Angle (:Size/2) / Sin :Angle/2
    Forward :Dist Left 180]
end

to arch :angle :radius
  # symmetrical arc drawn relative to turtle heading
  Arc :Radius Heading-:Angle/2 Heading+:Angle/2
end

to go
  New
  For [Ang 150 10 -20] [    # 230 10 -20
    Home Left 45
    SetPC Green Lens :Ang 448    # 256
    SetPC (List :Ang :Ang :Ang) Fill
    Back 1.15 *:Ang Right 45 
    SetPC White Label :Ang Wait 30]
  SetPos [-190 182] Label [Lens Shapes]
end