/*
- Original: Philip Winston (pwinston@yahoo.com)
- 'Scrolling Fix' by Troels Jakobsen <tjak@get2net.dk>
- Adapted for XTHML + Netscape/Mozilla/FireFox/... by GhislainLavoie on <http://www.editeurjavascript.com/forum>, vwphillips on <http://js-x.com/forum> and Ludwig von 97 (http://www.webisdead.net) , thanks to Willy Duitt too. Last update 21st September 2004 by Ludwig von 97 (http://www.webisdead.net)

* DOTSIZEHEIGHT and DOTSIZEWIDTH arrays must be filled manually for now.
*  To use in HTML instead of XHTML, replace "documentElements" by "body".
*/

var nDots = 7; // must be equal to the number of elements (including "dot0")
var Xpos = 0;
var Ypos = 0;
var Ypos = 0;

var DELTAT = .01;
var SEGLEN = 5;
var SPRINGK = 6;
var MASS = 2;
var GRAVITY = 0;
var RESISTANCE = 10;
var STOPVEL = 0.1;
var STOPACC = 0.1;
var BOUNCE = 0.60;
var DOTSIZEHEIGHT = new Array(9,11,23,16,21,24,29); // two dimensions dotsize, must be equal to respective elements height (LV97)
var DOTSIZEWIDTH = new Array(12,12,18,24,31,37,40); // two dimensions dotsize, must be equal to respective elements width (LV97)
var isNetscape = navigator.appName=="Netscape";
var followmouse = true;
var dots = new Array();
init();

function init() {
var i = 0;
for (i = 0; i < nDots; i++) {
dots[i] = new dot(i);
}
if (!isNetscape) {
// I only know how to read the locations of the
// <LI> items in IE
// skip this for now
// setInitPositions(dots)
}
for (i = 0; i < nDots; i++) {
dots[i].obj.left = dots[i].X+"px"; // "+"px"" (XHTML related) suggested by GhislainLavoie
dots[i].obj.top = dots[i].Y+"px"; // "+"px"" (XHTML related) suggested by GhislainLavoie
}
if (isNetscape) {startanimate();}
else {
// let dots sit there for a few seconds
// since they're hiding on the real bullets
setTimeout("startanimate()", 3000);}}

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

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

function setInitPositions(dots) {
var startloc = document.all.tags("LI");
var i = 0;
for (i = 0; i < startloc.length && i < (nDots - 1); i++) {
dots[i+1].X = startloc[i].offsetLeft
startloc[i].offsetParent.offsetLeft - DOTSIZEWIDTH[i]; // two dimension dotsize + adaptable width (LV97)
dots[i+1].Y = startloc[i].offsetTop +
startloc[i].offsetParent.offsetTop + 2*DOTSIZEHEIGHT[i]; // two dimension dotsize + adaptable height (LV97)
}
dots[0].X = dots[1].X;
dots[0].Y = dots[1].Y - SEGLEN;
}

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

function MoveHandlerIE() {
Xpos = window.event.x + document.documentElement.scrollLeft; // previously "documentElement" --> "body" (LV97)
Ypos = window.event.y + document.documentElement.scrollTop; // previously "documentElement" --> "body" (LV97)
}
if (isNetscape) {
// "document.captureEvents(Event.MOUSEMOVE);" <-- removed by GhislainLavoie
document.onmousemove = MoveHandler;
} else {
document.onmousemove = MoveHandlerIE;
}

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(){
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);
}
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;
height = document.documentElement.clientHeight + document.documentElement.scrollTop;
width = document.documentElement.clientWidth + document.documentElement.scrollLeft;
// the two above lines: previously "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;}" (LV97 & vwphillips)
if (dots[i].Y >=  height - DOTSIZEHEIGHT[i] - 1) { // two dimensions dotsize adapted + adaptable height (LV97)
if (dots[i].dy > 0) {
dots[i].dy = BOUNCE * -dots[i].dy;
}
dots[i].Y = height - DOTSIZEHEIGHT[i] - 1; // two dimensions dotsize adapted + adaptable height (LV97)
}
if (dots[i].X >= width - DOTSIZEWIDTH[i] - 1) { // two dimensions dotsize adapted + adaptable width (LV97)
if (dots[i].dx > 0) {
dots[i].dx = BOUNCE * -dots[i].dx;
}
dots[i].X = width - DOTSIZEWIDTH[i] - 1; // two dimensions dotsize adapted + adaptable width (LV97)
}
if (dots[i].X < 0) {
if (dots[i].dx < 0) {
dots[i].dx = BOUNCE * -dots[i].dx;
}
dots[i].X = 0;
}
dots[i].obj.left = dots[i].X+"px"; // "+"px"" (XHTML related) suggested by GhislainLavoie
dots[i].obj.top = dots[i].Y+"px"; // "+"px"" (XHTML related) suggested by GhislainLavoie
}}