Contents

########################################################
# Chequer implemented using a grammar library
# Lindenmayer System in ruby-processing by Martin Prout
########################################################


load_libraries 'grammar'

attr_reader :chequer

def setup
  size 600, 600
  @chequer = Chequer.new width * 0.9, height/10
  chequer.create_grammar 4  
  no_loop
end

def draw
  background 0
  chequer.render
end

class Chequer
  include Processing::Proxy
  import 'grammar'
  attr_accessor :axiom, :grammar, :production, :draw_length, :theta, :xpos, :ypos
  DELTA = HALF_PI
  
  def initialize xpos, ypos
    @xpos = xpos 
    @ypos = ypos 
    @axiom = "F-F-F-F"        # Axiom
    @grammar = Grammar.new(
      axiom,
      {"F" => "FF-F-F-F-FF"}  # Rules
   )
    @draw_length = 500
    stroke 0, 255, 0
    stroke_weight 2  

    @theta = 0
  end
  
  def render
    production.each do |element|
      case element
      when 'F'                     
        x_temp = xpos
        y_temp = ypos
        @xpos -= draw_length * cos(theta) 
        @ypos -= draw_length * sin(theta)
        line(x_temp, y_temp, xpos, ypos)
      when '+'
        @theta += DELTA
      when '-'
        @theta -= DELTA
      else
        puts "Character '#{element}' is not in grammar"
      end
    end
  end
  
  ##############################
  # create grammar from axiom and
  # rules (adjust scale)
  ##############################
  
  def create_grammar(gen)
    @draw_length /=  3**gen
    @production = @grammar.generate gen
  end
end

Version data entries

4 entries across 4 versions & 1 rubygems

Version	Path
ruby-processing-2.4.4	samples/processing_app/topics/lsystems/chequer.rb
ruby-processing-2.4.3	samples/processing_app/topics/lsystems/chequer.rb
ruby-processing-2.4.2	samples/processing_app/topics/lsystems/chequer.rb
ruby-processing-2.4.1	samples/processing_app/topics/lsystems/chequer.rb