// Attach this to a GUIText to make a frames/second indicator.
  //
  // It calculates frames/second over each updateInterval,
  // so the display does not keep changing wildly.
  //
  // It is also fairly accurate at very low FPS counts (<10).
  // We do this not by simply counting frames per interval, but
  // by accumulating FPS for each frame. This way we end up with
  // correct overall FPS even if the interval renders something like
  // 5.5 frames.
   
  var updateInterval = 0.5;
   
  private var accum = 0.0; // FPS accumulated over the interval
  private var frames = 0; // Frames drawn over the interval
  private var timeleft : float; // Left time for current interval
   
  function Start()
  {
          if( !guiText )
          {
                  print ("FramesPerSecond needs a GUIText component!");
                  enabled = false;
                  return;
          }
          timeleft = updateInterval;        
  }
   
  function Update()
  {
          timeleft -= Time.deltaTime;
          accum += Time.timeScale/Time.deltaTime;
          ++frames;
          
          // Interval ended - update GUI text and start new interval
          if( timeleft <= 0.0 )
          {
                  // display two fractional digits (f2 format)
                  guiText.text = "" + (accum/frames).ToString("f2");
                  timeleft = updateInterval;
                  accum = 0.0;
                  frames = 0;
          }
  }
  
  @script RequireComponent (GUIText)