    def export_simple file_name, export_index_buffer = false
      file_name += ".simple" unless /\.simple$/.match file_name

      if export_index_buffer
        vi = compute_vertex_and_index_buffer
        vertex_buffer = vi[:vertex_buffer]
        index_buffer = vi[:index_buffer]
      else
        vertex_buffer = compute_vertex_buffer
      end

      ::File.delete file_name if ::File.exist? file_name
      open file_name, 'a' do |f|
        f.puts "# Exported in Simple Format from Wavefront Ruby Gem Version #{Wavefront::VERSION}"
        f.puts "#vertices"
        vertex_buffer.each do |v|
          vertex_str = "p,#{v.position.to_a.join ','}"
          vertex_str += ",n,#{v.normal.to_a.join ','}" if v.normal
          vertex_str += ",t,#{v.tex.to_a.join ','}" if v.tex
          f.puts vertex_str
        end
        if export_index_buffer
          f.puts "\n\n\n#indices"
          f.puts index_buffer.join ','
        end
      end
    end