Seasonal sketch, adding terminals to L-System plant

Revised version as of 10th January 2010 now uses my grammar library.


########################################################
# Lindenmayer System in ruby-processing by Martin Prout
# Exploring terminals with minimum logic (Seasonal)
########################################################

require 'seasonal'

class Seasonal_Test < Processing::App
  load_library :grammar
  
  attr_reader :seasonal
  
  def setup
    size 600, 800
    @seasonal = Seasonal.new
    seasonal.create_grammar(3)
    no_loop
  end
  
  def draw
    background 0
    seasonal.render
  end
end

############################
# seasonal.rb
###########################


class Seasonal  
  include Processing::Proxy 
  
  attr_reader :grammar, :axiom, :draw_length, :theta, :xpos, :ypos, :production
  DELTA = Math::PI/4
  
  def initialize    
    @axiom = "F"
    @grammar = Grammar.new axiom
    grammar.add_rule("F", "F[-F]F[+F][F]")
    @draw_length = 600
    @xpos = width/2
    @ypos = height * 0.9
    @theta = Math::PI/2  # this way is up?    
  end

  def render
    stack = Array.new               # directly using locally defined array as turtle stack
    production.each_char do |element|
      case element
      when 'F'                     # NB NOT using affine transforms
        x_temp = xpos
        y_temp = ypos
        @xpos += draw_length * Math.cos(theta) * 0.5 # looks neater here
        @ypos -= draw_length * Math.sin(theta) * 0.5
        stroke 0, 255, 0
        stroke_weight 4    
        line(x_temp, y_temp, xpos, ypos)
      when '+'
        @theta += DELTA      
      when '-'
        @theta -= DELTA      
      when '['
        stack.push([xpos, ypos, theta])
      when ']'
        no_stroke
        fill 255, 0, 0
        # add some seasonal red berries as terminals using minimal logic
        ellipse(xpos, ypos, draw_length/3, draw_length/3) unless stack.length < 2 
        @xpos, @ypos, @theta = *stack.pop
      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 *=  0.5**gen
    @production = @grammar.generate gen
  end
end