/* 
if (document.all&&window.print)
 document.body.style.cssText="overflow-x: hidden; overflow-y: scroll" 
*/

var Xpos = 0;
var Ypos = 0;

// Фиксируется временной промежуток
var DELTAT = .008;
// Размеры
var SEGLEN = 10;
var SPRINGK = 10;
// Фиксируются физические константы
var MASS = 4;
var GRAVITY = 20;
var RESISTANCE = 15;
// Условия останова
var STOPVEL = 0.1;
var STOPACC = 0.1;
// Дополнительные условия
var BOUNCE = 0.75;

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

var isDOM = document.getElementById //DOM1 browser (MSIE 5+, Netscape 6, Opera 5+)
var isOpera = isOpera5 = window.opera && isDOM //Opera 5+
var isOpera6 = isOpera && window.print //Opera 6+
var isOpera7 = isOpera && document.readyState //Opera 7+
var isMSIE = document.all && document.all.item && !isOpera //Microsoft Internet Explorer 4+
var isMSIE5 = isDOM && isMSIE //MSIE 5+
var isNetscape4 = document.layers //Netscape 4.*
var isMozilla = isDOM && navigator.appName=="Netscape" //Mozilla или Netscape 6.*

var followmouse = true;

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

function init()
{
 var i = 0;
 for (i = 0; i < nDots; i++) {
 dots[i] = new dot(i);
 dots[i].obj.left = 0;
 dots[i].obj.top = 0;
 }
 // set their positions
 for (i = 0; i < nDots; i++) {
 dots[i].obj.left = dots[i].X;
 dots[i].obj.top = dots[i].Y;
 }
 startanimate();
}

function startanimate() {	
 setInterval("animate()", 20);
 if (HideAn==0) {
  for (i = 1; i < nDots; i++) {
   document.getElementById('dot'+i).style.visibility="visible"
 }}
}

function dot(i) 
{
 this.X = Xpos;
 this.Y = Ypos;
 this.dx = 0;
 this.dy = 0;
 this.obj = eval("document.getElementById('dot" + i + "').style");
}

// just save mouse position for animate() to use
Xpos = 0
Ypos = 0
if(isNetscape4) document.captureEvents(Event.MOUSEMOVE)
if(isMSIE || isOpera7){
  document.onmousemove=function(){
    Xpos = event.clientX + document.body.scrollLeft
    Ypos = event.clientY + document.body.scrollTop
    return true
  }
}else if(isOpera){
  document.onmousemove=function(){
    Xpos = event.clientX
    Ypos = event.clientY
    return true
  }
}else if(isNetscape4 || isMozilla){
  document.onmousemove=function(e){
    Xpos = e.pageX
    Ypos = e.pageY
    return true
  }  
}

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] follows the mouse,
 // though no dot is drawn there
 var start = 0;
 if (followmouse) {
 dots[0].X = Xpos;
 dots[0].Y = Ypos;	
 start = 1;
 }
 
 for (i = start ; 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);
 }
 
 // air resisitance/friction
 var resist = new vec(-dots[i].dx * RESISTANCE,-dots[i].dy * RESISTANCE);
 
 // compute new accel, including gravity
 var accel = new vec((spring.X + resist.X)/ MASS,
 (spring.Y + resist.Y)/ MASS + GRAVITY);
 
 // compute new velocity
 dots[i].dx += (DELTAT * accel.X);
 dots[i].dy += (DELTAT * accel.Y);
 
 // stop dead so it doesn't jitter when nearly still
 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;
 }
 
 // move to new position
 dots[i].X += dots[i].dx;
 dots[i].Y += dots[i].dy;
 
 // get size of window
 var height, width;
 if (isNetscape4) {
 height = window.innerHeight + window.pageXOffset;
 width = window.innerWidth + window.pageYOffset;
 } else {	
 height = document.body.clientHeight + document.body.scrollTop;
 width = document.body.clientWidth + document.body.scrollLeft;
 }
 
 // bounce of 3 walls (leave ceiling open)
 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;
 }
 
 // move img to new position
 dots[i].obj.left = dots[i].X;			
 dots[i].obj.top = dots[i].Y;		
 }
}