# Main Command: GoX
# L_System 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 display :lsys :order
  # write header title, curve depth and info 
  SetPC White
  SetPos [-190 184] Label (List "L-System: :LSys :Name)
  SetPos [-190 -192] Label (List "Rule: "F: :Rule)
  SetPos [130 -192] Label List "Axiom: :Axiom
  SetPos [130 184] Label List "Order: :Order
  SetPos [130 170] Label List "Angle: :Angle
end

to generate :string :order
  If :Order < 1 [Output :String]
  Output Generate (ReWrite :String) :Order-1
end

to rewrite :string
  # replace every F with rule
  Make "NewString "
  For (List "N 1 Count :String) [
    Make "Symbol Item :N :String
    If :Symbol = "F [Make "NewString Word :NewString :Rule] [
    Make "NewString Word :NewString :Symbol] ]
  Output :NewString
end

to draw :string
  # render each symbol in string
  ForEach "Symbol :String [
    If :Symbol = "F [Forward :Step] [
    If :Symbol = "+ [Right :Angle] [
    If :Symbol = "- [Left :Angle] ] ] ]
end

to l_sys1 :order
  Make "Name "Snowflake_Curve
  Make "Scale 3
  Make "Angle 60 
  Make "Rule "F-F++F-F
end

to l_sys2 :order
  Make "Name "Koch_Square
  Make "Scale 3
  Make "Angle 90 
  Make "Rule "F-F+F+F-F
end

to l_sys3 :order
  Make "Name "Peano_Curve
  Make "Scale 3
  Make "Angle 90 
  Make "Rule "F-F+F+F+F-F-F-F+F
end

to l_sys4 :order
  Make "Name "Quadratic_Koch_Curve
  Make "Scale 4
  Make "Angle 90 
  Make "Rule "F+F-F-FF+F+F-F   # or add in extra central F 
end

to l_sys5 :order
  Make "Name "Modified_Snowflake_Curve
  Make "Scale 4
  Make "Angle 60 
  Make "Rule "F-F+F+F-F
end

to l_sys6 :order
  Make "Name "Modified_Snowflake_Curve2
  Make "Scale 4 
  Make "Angle 60 
  Make "Rule "F-F++FF--F+F
end

to l_sys7 :order
  Make "Name "Modified_Snowflake_Curve3
  Make "Scale 3
  Make "Angle 60 
  Make "Rule "F-F++F++F--F--F+F
end

to go :lsys :order
  New
  Make "Screen 384 Make "Axiom "F
  Wash Home
  Run Word "L_Sys :LSys :Order 
  Display :Lsys :Order SetPC Green
  Make "Step :Screen/Power :Scale :Order 
  Make "DrawString Generate :Axiom :Order
  If :Order < 2 [Print :DrawString] [Print [printout supressed] ]
  SetPos List Minus :Screen/2 0 SetH 90
  PenDown Draw :DrawString PenUp
end

to gox
  New
  Make "Screen 384 Make "Order 3 Make "Axiom "F
  For [LSys 1 7] [
    Wash Home Make "Step :Screen
    Run Word "L_Sys :LSys :Order 
    Display :Lsys :Order
    Make "DrawString :Axiom
      For (List "Ord 1 :Order) [
      Make "DrawString ReWrite :DrawString
      SetPos List Minus :Screen/2 0 SetH 90
      Make "Step :Step / :Scale
      SetPC Item :Ord [3 1 6 2]
      SetPW Item (:Order+1)-:Ord [1 5 9 11]
  PenDown Draw :DrawString PenUp Wait 60] Wait 120]
end