Langton Ant written with ruby-processing

rangton.rb

# Langton Ant in ruby-processing

class LangtonAnt < Processing::App

  WHITE = -1
  BLACK = -16777216

  DefaultMovements = {
    :up    => { WHITE => :right, BLACK => :left  },
    :down  => { WHITE => :left,  BLACK => :right },
    :left  => { WHITE => :up,    BLACK => :down  },
    :right => { WHITE => :down,  BLACK => :up    },
  }

  DefaultColorChanges = {
    WHITE => 0,
    BLACK => 255
  }

  def setup
    frame_rate 100
    @direction = :up
    @x = width / 2
    @y = height / 2

    background 255
  end

  def draw
    # Step onto the next pixel
    case @direction
    when :up then
      @y = (@y - 1) % height
    when :down then
      @y = (@y + 1) % height
    when :left then
      @x = (@x - 1) % width
    when :right then
      @x = (@x + 1) % width
    end

    # Change pixel color
    prev_color = get(@x,@y)
    new_color  = DefaultColorChanges[prev_color]
    set(@x, @y, color(new_color))

    # Set new direction
    @direction = DefaultMovements[@direction][prev_color]
  end

end

LangtonAnt.new :title => "Langton Ant", :width => 300, :height => 300