Lindenmayer system in ruby-processing

##
# Lindenmayer System in ruby-processing by Martin Prout
# Loosely based on processing Pentigree L-System by Geraldine Sarmiento
###

require 'pentigree'

class Pentigree_Test < Processing::App 
  load_library :grammar
  attr_reader :pentigree
  def setup
    size 800, 800
    @pentigree = Pentigree.new
    pentigree.create_grammar(5)  
    no_loop
  end
  
  def draw
    background 0
    pentigree.render
  end
end

######################
# pentigree.rb
######################
class Pentigree
  include Processing::Proxy  
 
  attr_reader :axiom, :grammar, :start_length, :theta, :production, :generations, :draw_length
  
  def initialize
    @axiom = "F-F-F-F-F"
    @grammar = Grammar.new(axiom)
    grammar.add_rule("F", "F-F++F+F-F-F")
    @start_length = 40.0
    @theta = (Math::PI/180) * 72.0 # convert degrees to radians
    @production = axiom
    @draw_length = start_length
  end
    
  def render 
    translate(width * 0.8, height * 0.75)
    @production.each_char do |prod|      
      case prod
      when 'F'
        no_fill
        stroke 255
        line(0, 0, 0, draw_length)        
        translate(0, draw_length)
      when '+' 
        rotate(theta)
      when '-'
        rotate(-theta)
      when '['
        push_matrix()
      when ']' 
        pop_matrix()
      else            
        puts "Character '#{element}' is not in grammar" 
      end
    end
  end
  
  def create_grammar(gen)
    @draw_length *=  0.6**gen
    @production = grammar.generate gen
  end
end