gistfile1.rb

class Clock
    def tick()
        passed = Clock.runtime() - @last_tick  # how long since the last tick?
        if @target_frametime
          wait = @target_frametime - passed
          if wait > 0
            return Clock.wait(@target_frametime - passed) + passed
          else
            return passed
          end
#          return Clock.delay(@target_frametime - passed, 1) + passed
        end
        return passed
      ensure
        @last_tick = Clock.runtime()
        @ticks += 1
    end
  end