Another Snake Kolam in ruby-processing demonstrates the use of PGraphicsPDF

	#############################################################
	# library/grammar.rb
	# Non-stochastic grammar
	# with unique premise/rules
	############################################################
	class Grammar
	attr_accessor :axiom, :rules
	def initialize axiom
	@axiom = axiom
	@rules = Hash.new
	end
	def add_rule premise, rule
	rules.store(premise, rule)
	end
	##########################################
	# replace each pre char with a unique rule
	##########################################
	def new_production production
	production.gsub!(/./) { |c| (r = @rules[c]) ? r : c }
	end
	##########################################
	# control the number of iterations
	# default 0, returns the axiom
	##########################################
	def generate repeat = 0
	prod = String.new(axiom) # retain original axiom
	repeat.times do
	prod = new_production prod
	end
	return prod
	end
	#############################################
	# Returns a string thst describes the LSystem
	#############################################
	def to_string
	rule = "Axiom: #{axiom}\nSubstitution Rules:\n"
	rules.each{|pr| rule << "#{pr[0]} => #{pr[1]}\n"}
	return rule
	end
	end

view raw grammar.rb hosted with ❤ by GitHub

	#######################################################
	# Lindenmayer System in ruby-processing by Martin Prout
	# Demonstrates export to PDF format
	#######################################################
	require 'snake_kolam'
	class Kolam_Test < Processing::App
	load_libraries :grammar, :pdf
	import "processing.pdf.PGraphicsPDF"
	attr_reader :snake, :my_font
	def setup
	size 900, 900, P2D
	@snake = SnakeKolam.new
	snake.create_grammar 4
	background(255)
	hint(ENABLE_NATIVE_FONTS)
	@my_font = create_font("/usr/share/fonts/truetype/freefont/FreeSans.ttf", 18) # for the benefit linux users
	# @my_font = create_font(Any suitable ttf font, 18)
	background 255
	stroke 0
	render_to_PDF
	end
	def render_to_PDF
	begin_record PDF, "/home/tux/kolam.pdf" # requires an absolute address for output file
	snake.render # render kolam (NB text does not appear in frame)
	fill 0 # font fill
	text_mode(SHAPE) # fonts as shape
	textFont(my_font, 18)
	text("Snake Kolam", 300, 40) # title
	text(snake.to_string, 100, 780) # lsystem values
	end_record
	end
	end

view raw kolam.rb hosted with ❤ by GitHub

	############################
	# snake_kolam.rb using l-systems
	############################
	class SnakeKolam
	include Processing::Proxy
	attr_accessor :axiom, :start_length, :xpos, :ypos, :grammar, :production, :draw_length, :gen
	XPOS = 0
	YPOS = 1
	ANGLE = 2
	DELTA = (Math::PI/180) * 90.0 # convert degrees to radians
	def initialize
	setup_grammar
	@start_length = 160.0
	@theta = (Math::PI/180) * 90.0 # convert degrees to radians
	@draw_length = start_length
	@draw_length = start_length
	@xpos = width/8
	@ypos = height*0.8
	end
	def setup_grammar
	@axiom = "FX+F+FX+F"
	@grammar = Grammar.new(axiom)
	grammar.add_rule("X", "X-F-F+FX+F+FX-F-F+FX")
	end
	def render # NB not using affine transforms here
	turtle = [xpos, ypos, 0.0]
	production.scan(/./).each do |element|
	case element
	when 'F'
	turtle = draw_line(turtle, draw_length)
	when '+'
	turtle[ANGLE] += DELTA # rotate by + theta if going the affine transform route
	when '-'
	turtle[ANGLE] -= DELTA # rotate by - theta if going the affine transform route
	when 'X' # do nothing except recognize 'X' as a word in the L-system grammar
	else
	puts "Character '#{element}' is not in grammar"
	end
	end
	end
	##############################
	# create grammar from axiom and
	# rules (adjust scale)
	##############################
	def create_grammar(gen)
	@gen = gen
	@draw_length *= 0.6**gen
	@production = @grammar.generate gen
	end
	def to_string
	rule = "Repeats: #{gen}\n"
	rule << grammar.to_string
	end
	private
	######################################################
	# draws line using current turtle and length parameters
	# returns a turtle corresponding to the new position
	######################################################
	def draw_line(turtle, length)
	new_xpos = turtle[XPOS] + length * Math.cos(turtle[ANGLE])
	new_ypos = turtle[YPOS] + length * Math.sin(turtle[ANGLE])
	line(turtle[XPOS], turtle[YPOS], new_xpos, new_ypos)
	turtle = [new_xpos, new_ypos, turtle[ANGLE]]
	end
	end

view raw snake_kolam.rb hosted with ❤ by GitHub