// 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)