Towards Penrose Tiling Using ruby-processing context-free DSL

#########################
# rubystar.rb
#########################
load_library 'context_free'

PHI = (1 + Math.sqrt(5))/2

def setup_the_sunstar
  @hexa = ContextFree.define do
  ############ Begin defining custom terminals, as a sharp and flat triangles
    class << self
    include Math
      define_method(:sharp) do |some_options|      
        size, options = *self.get_shape_values(some_options)
        rot = options[:rotation]
        rotate(rot) if rot           # NB: sin(0) = 0, cos(0) = 1                                        
        super.triangle(0, 0, size, 0, size * cos(PI/5), size * sin(PI/5))
        rotate(-rot) if rot
      end
      define_method(:flat) do |some_options|      
        size, options = *self.get_shape_values(some_options)
        rot = options[:rotation]
        rotate(rot) if rot
        f = (options[:flip])? -1 : 1  # flip adjustment NB: sin(0) = 0, cos(0) = 1
        super.triangle(0, 0, size/PHI, 0, size * cos(PI * f/5), size * sin(PI * f/5))
        rotate(-rot) if rot
      end
    end
    ########### End definition of custom terminals 'sharp and flat'
    rule :tiling do    
      sun :brightness => 0.8
      star :brightness => 0.8, :alpha => 0.8
      tiling :size => 1/PHI, :brightness => 1.0
    end
  
    rule :dart do
      flat :size => 1, :color => [0.18, 0.6, 0.6]
      flat :size => 1, :color => [0.18, 1.0, 1.0], :flip => true
    end
  
    rule :kite do
      sharp :size => 1, :color => [0, 0.6, 0.6]
      sharp :size => 1, :color => [0, 1.0, 1.0], :rotation => 180, :flip => true
    end
  
    rule :star do    
      split do
        5.times do |i|
          dart :rotation => 72 * i
          rewind
        end
      end
    end
  
    rule :sun do
      split do
        5.times do |i|
          kite :rotation => 72 * i
          rewind
        end
      end
    end
  end
end

def setup
  size 800, 800
  background 150, 20, 0
  smooth
  setup_the_sunstar
  draw_it
end

def draw_it
  @hexa.render :tiling, :start_x => width/2, :start_y => height/2,
               :size => height
end