var nds = 10;

var Xpos = 0;
var Ypos = 0;

  
var DELTAT = .01;
  
var SEGLEN = 25;
  
var SPRINGK = 5;
  
  
var MASS = 1;


var XGRAVITY = 0;
var YGRAVITY = 50;

var RESISTANCE = 10;
  
  
  
  
var STOPVEL = 0.1;
var STOPACC = 0.1;
var dSIZE = 11;
   
  
var BOUNCE = 0.75;

var isNetscape = navigator.appName=="Netscape";

  
  
var followmouse = true;

var ds = new Array();
init();

function init()
{
    var i = 0;
    for (i = 0; i < nds; i++) {
        ds[i] = new d(i);
    }
    
    if (!isNetscape) {
         
        
        
        
    }
    
    
    for (i = 0; i < nds; i++) {
        ds[i].obj.left = ds[i].X;
        ds[i].obj.top = ds[i].Y;
    }
    
    
    if (isNetscape) {
        
        
        startanimate();
    } else {
        
        
        setTimeout("startanimate()", 1000);
    }
}



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


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





function setInitPositions(ds)
{
     
    
    var startloc = document.all.tags("LI");
    var i = 0;
    for (i = 0; i < startloc.length && i < (nds - 1); i++) {
        ds[i+1].X = startloc[i].offsetLeft
            startloc[i].offsetParent.offsetLeft - dSIZE;
        ds[i+1].Y = startloc[i].offsetTop +
            startloc[i].offsetParent.offsetTop + 2*dSIZE;
    }
    
    ds[0].X = ds[1].X;
    ds[0].Y = ds[1].Y - SEGLEN;
}


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


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

if (isNetscape) {
    document.captureEvents(Event.MOUSEMOVE);
    document.onMouseMove = MoveHandler;
} else {
    document.onmousemove = MoveHandlerIE;
}


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


function springForce(i, j, spring)
{
    var dx = (ds[i].X - ds[j].X);
    var dy = (ds[i].Y - ds[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() {	
    
    
    var start = 0;
    if (followmouse) {
        ds[0].X = Xpos;
        ds[0].Y = Ypos; 
        start = 1;
    }
    
    for (i = start ; i < nds; i++ ) {
        
        var spring = new vec(0, 0);
        if (i > 0) {
            springForce(i-1, i, spring);
        }
        if (i < (nds - 1)) {
            springForce(i+1, i, spring);
        }
        
        
        var resist = new vec(-ds[i].dx * RESISTANCE,
            -ds[i].dy * RESISTANCE);
        
        
        var accel = new vec((spring.X + resist.X)/MASS + XGRAVITY,
            (spring.Y + resist.Y)/ MASS + YGRAVITY);
        
        
        ds[i].dx += (DELTAT * accel.X);
        ds[i].dy += (DELTAT * accel.Y);
        
        
        if (Math.abs(ds[i].dx) < STOPVEL &&
            Math.abs(ds[i].dy) < STOPVEL &&
            Math.abs(accel.X) < STOPACC &&
            Math.abs(accel.Y) < STOPACC) {
            ds[i].dx = 0;
            ds[i].dy = 0;
        }
        
        
        ds[i].X += ds[i].dx;
        ds[i].Y += ds[i].dy;
        
        
        var height, width;
        if (isNetscape) {
            height = window.innerHeight + window.pageYOffset;
            width = window.innerWidth + window.pageXOffset;
        } else {	
            height = document.body.clientHeight + document.body.scrollTop;
            width = document.body.clientWidth + document.body.scrollLeft;
        }
        
        
        if (ds[i].Y >=  height - dSIZE - 1) {
            if (ds[i].dy > 0) {
                ds[i].dy = BOUNCE * -ds[i].dy;
            }
            ds[i].Y = height - dSIZE - 1;
        }
        if (ds[i].X >= width - dSIZE) {
            if (ds[i].dx > 0) {
                ds[i].dx = BOUNCE * -ds[i].dx;
            }
            ds[i].X = width - dSIZE - 1;
        }
        if (ds[i].X < 0) {
            if (ds[i].dx < 0) {
                ds[i].dx = BOUNCE * -ds[i].dx;
            }
            ds[i].X = 0;
        }
        
        
        ds[i].obj.left = ds[i].X;            
        ds[i].obj.top =  ds[i].Y;    
    }
}