var nDots = 2;
var Xpos = 0;
var Ypos = 0;

var DELTAT = .005;
var SEGLEN = 10;
var SPRINGK = 5;
var MASS = 1;
var GRAVITY = 10;
var RESISTANCE = 30;
var STOPVEL = 0.1;
var STOPACC = 0.1;
var DOTSIZE = 40;
var BOUNCE = 0.5;
var first = 1;

var isNetscape = navigator.appName=="Netscape";
var followmouse = true;
var dots = new Array();

function init()
{
	var i;

dots[0] = new dot(0);

for (i = 1; i < nDots; i++)
	{
		dots[i] = new dot(i);
		dots[i].obj.left = dots[i].X;
		dots[i].obj.top = dots[i].Y;
	}
}

function dot(i)
{
	this.X = Xpos;
	this.Y = Ypos;
	this.dx = 0;
	this.dy = 0;
	if(i==0) return;// riferimento
	if (isNetscape)
	{
		this.obj = eval("document.dot" + i);
	}
	else
	{
		this.obj = eval("dot" + i + ".style");
	}
}

function startanimate()
{
	setInterval("animate()", 20);
}

function MoveHandler(e)
{
	if (followmouse)
	{
		Xpos = e.pageX;
		Ypos = e.pageY;
	}
	else
	{
		Xpos = 0;
		Ypos = 0;
	}
	return true;
}

function MoveHandlerIE()
{
	if (followmouse)
	{
		Xpos = window.event.x + document.body.scrollLeft;
		Ypos = window.event.y + document.body.scrollTop;
	}
	else
	{
		Xpos = 0;
		Ypos = 0;
	}
}

function vec(X,Y)
{
	this.X = X;
	this.Y = Y;
}

// adds force in X and Y to spring for dot[i] on dot[j]
function springForce(i, j, spring)
{
	var dx = (dots[i].X - dots[j].X);
	var dy = (dots[i].Y - dots[j].Y);
	var len = Math.sqrt(dx*dx + dy*dy);
	if (len > SEGLEN)
	{
		var springF = SPRINGK * (len - SEGLEN);
		spring.X += (dx / len) * springF;
		spring.Y += (dy / len) * springF;
	}
}

function animate()
{
		dots[0].X = Xpos+10;
		dots[0].Y = Ypos+10;

	for (i = 1 ; i < nDots; i++ )
	{
		var spring = new vec(0, 0);
		if (i > 0)
		{
			springForce(i-1, i, spring);
		}
		if (i < (nDots - 1))
		{
			springForce(i+1, i, spring);
		}

		var resist = new vec(-dots[i].dx * RESISTANCE, -dots[i].dy * RESISTANCE);
		var accel = new vec((spring.X + resist.X)/ MASS, (spring.Y + resist.Y)/ MASS + GRAVITY);
		dots[i].dx += (DELTAT * accel.X);
		dots[i].dy += (DELTAT * accel.Y);
		if (Math.abs(dots[i].dx) < STOPVEL &&
				Math.abs(dots[i].dy) < STOPVEL &&
				Math.abs(accel.X) < STOPACC &&
				Math.abs(accel.Y) < STOPACC)
		{
			dots[i].dx = 0;
			dots[i].dy = 0;
		}
		dots[i].X += dots[i].dx;
		dots[i].Y += dots[i].dy;
		var height, width;
		if (isNetscape)
		{
			height = window.innerHeight + document.scrollTop;
			width = window.innerWidth + document.scrollLeft;
		}
		else
		{
			height = document.body.clientHeight + document.body.scrollTop;
			width = document.body.clientWidth + document.body.scrollLeft;
		}
		if (dots[i].Y >=  height - DOTSIZE - 1)
		{
			if (dots[i].dy > 0)
			{
				dots[i].dy = BOUNCE * -dots[i].dy;
			}
			dots[i].Y = height - DOTSIZE - 1;
		}
		if (dots[i].X >= width - DOTSIZE)
		{
			if (dots[i].dx > 0)
			{
				dots[i].dx = BOUNCE * -dots[i].dx;
			}
			dots[i].X = width - DOTSIZE - 1;
		}
		if (dots[i].X < 0)
		{
			if (dots[i].dx < 0)
			{
				dots[i].dx = BOUNCE * -dots[i].dx;
			}
			dots[i].X = 0;
		}
		if (first)
		{
			dots[i].obj.visibility = "visible";
			dots[i].obj.left = dots[i].X = Xpos+10;
			dots[i].obj.top =  dots[i].Y = Ypos+10;
			first=0;
		}
		else
		{
			dots[i].obj.left = dots[i].X;
			dots[i].obj.top =  dots[i].Y;
		}
	}
}

function SetCookie(sName, sValue)
{
	document.cookie = sName + "=" + escape(sValue) + "; expires=" + "Mon, 5 Oct 2099 12:40:34 GMT";
}

function GetCookie(sName)
{
  // cookies are separated by semicolons
  var aCookie = document.cookie.split("; ");
  for (var i=0; i < aCookie.length; i++)
  {
    // a name/value pair (a crumb) is separated by an equal sign
    var aCrumb = aCookie[i].split("=");
    if (sName == aCrumb[0]) 
      return unescape(aCrumb[1]);
  }

  // a cookie with the requested name does not exist
  return null;
}

function toggledots()
{
	followmouse =!followmouse;
	SetCookie("followmouse",(followmouse?"Y":"N"));
	for (i = 1 ; i < nDots; i++ )
	{
			dots[i].obj.left = dots[i].X = 0;
			dots[i].obj.top =  dots[i].Y = 0;
	}
}

if (isNetscape)
{
	document.captureEvents(Event.MOUSEMOVE);
	document.onMouseMove = MoveHandler;
}
else
{
	document.onmousemove = MoveHandlerIE;
}
followmouse=(GetCookie("followmouse")=="Y"?true:false);
init();
setTimeout("startanimate()",1000);
// End -->