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john criten
10-30-2008, 08:17 AM
1) Script Title: elastic trail script

2) Script URL (on DD): http://www.dynamicdrive.com/dynamicindex13/trailer2.htm

3) Describe problem: when you scroll down the pag the trail is offset by the amount scrolled it does reaquire the correct mouse pos.

also i was wondering how i would add a sound that plays when the object is chasing the mouse and stops playing when it gets to the mouse and continues like this ie you had a car trailing the mouse and while it is chasing the mouse it plays an engine sound which stops playing within a radius of the mouse and tires screeching sound plays once inside the radius that stops once the object gets to the mouse cursor position.

jscheuer1
10-30-2008, 03:07 PM
That script is way out of date. Put this in the head of your page:


<style type="text/css">
.dot {
position: fixed;
}
#dot0 {
visibility: hidden;
}
</style>

Put this right after the <body> tag:


<script type="text/javascript">
/*
Elastic Trail script (By Philip Winston @ pwinston@yahoo.com, URL: http://www.geocities.com/pwinston/)
TOS featured on Dynamicdrive.com
For this and 100's more DHTML scripts, visit http://dynamicdrive.com
Updated by jscheuer1 in http://dynamicdrive.com/forums for modern browsers & DOCTYPES
*/

function elastic_trail(){

var nDots = 7;
var dotSrc = 'bullet.gif';

var Xpos = 0;
var Ypos = 0;

// fixed time step, no relation to real time
var DELTAT = .01;
// size of one spring in pixels
var SEGLEN = 10;
// spring constant, stiffness of springs
var SPRINGK = 10;
// all the physics is bogus, just picked stuff to
// make it look okay
var MASS = 1;
// Positive XGRAVITY pulls right, negative pulls left
// Positive YGRAVITY pulls down, negative up
var XGRAVITY = 0;
var YGRAVITY = 50;
// RESISTANCE determines a slowing force proportional to velocity
var RESISTANCE = 10;
// stopping criterea to prevent endless jittering
// doesn't work when sitting on bottom since floor
// doesn't push back so acceleration always as big
// as gravity
var STOPVEL = 0.1;
var STOPACC = 0.1;
var DOTSIZE = 11;
// BOUNCE is percent of velocity retained when
// bouncing off a wall
var BOUNCE = 0.75;

/////////////////Stop Editing the Script///////////////

for (var i = nDots - 1; i > -1; --i)

with(document){
write('<div class="dot" id="dot' + i +'">\n');
write('<img src="' + dotSrc + '" height="' + DOTSIZE + '" width="' + DOTSIZE + '" alt="">\n');
write('</div>\n');
}

/*@cc_on @*/
/*@if(@_jscript_version >= 5)
if(navigator.appVersion.replace(/^.*MSIE (\d+).*$/, '$1') <= 6){
var fixedIE = function(tl, n){
var sc='scroll'+tl, d=document, c='compatMode';
return d[c] && d[c]=='CSS1Compat'? d.documentElement[sc]+n+'px' : d.body[sc]+n+'px';
};
document.write('<style type="text/css">.dot {position: absolute;}body {background: url(foo) fixed;}<\/style>');
};
@end @*/

var iecompattest=function(){
return (document.compatMode && document.compatMode.indexOf("CSS")!=-1)? document.documentElement : document.body
}

var PX = document.layers? '' : 'px';

elastic_trail.prototype.dot=function(i)
{
this.X = Xpos;
this.Y = Ypos;
this.dx = 0;
this.dy = 0;
if (document.layers)
this.obj = document['dot' + i];
else if (document.all)
this.obj = document.all['dot' + i].style;
else if (document.getElementById)
this.obj = document.getElementById('dot' + i).style;
else
return;
}

var dots = new Array();

for (var i = 0; i < nDots; i++)
dots[i] = new this.dot(i);

// set their positions
for (i = 0; i < nDots; i++) {
dots[i].obj.left = typeof fixedIE == 'function' ? fixedIE('Left', dots[i].X) : Math.round(dots[i].X) + PX;
dots[i].obj.top = typeof fixedIE == 'function' ? fixedIE('Top', dots[i].Y) : dots[i].Y + PX;
}
var cacheobj=this;
setInterval(function(){cacheobj.animate();}, 20);

// just save mouse position for animate() to use
function MoveHandler(e){
Xpos = e.pageX - pageXOffset;
Ypos = e.pageY - pageYOffset;
return true;
}

// just save mouse position for animate() to use
function MoveHandlerIE() {
Xpos = window.event.x;
Ypos = window.event.y;
}

if (document.addEventListener)
document.addEventListener('mousemove', MoveHandler, false);
else if (document.attachEvent)
document.attachEvent('onmousemove', MoveHandlerIE);
else if (document.captureEvents){
document.captureEvents(Event.MOUSEMOVE);
document.onmousemove = MoveHandler;
}


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

// adds force in X and Y to spring for dot[i] on dot[j]
elastic_trail.prototype.springForce=function(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;
}
}


elastic_trail.prototype.animate=function() {
// dots[0] follows the mouse,
// though no dot is drawn there
var start = 0;
dots[0].X = Xpos;
dots[0].Y = Ypos;
start = 1;

for (var i = start ; i < nDots; i++ ) {

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

// air resisitance/friction
var resist = new this.vec(-dots[i].dx * RESISTANCE,
-dots[i].dy * RESISTANCE);

// compute new accel, including gravity
var accel = new this.vec((spring.X + resist.X)/MASS + XGRAVITY,
(spring.Y + resist.Y)/ MASS + YGRAVITY);

// 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 (window.innerWidth) {
height = window.innerHeight;
width = window.innerWidth;
} else {
height = iecompattest().clientHeight - Math.ceil(DOTSIZE/2);
width = iecompattest().clientWidth;
}

// bounce off 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 = typeof fixedIE == 'function' ? fixedIE('Left', dots[i].X) : Math.round(dots[i].X) + PX;
dots[i].obj.top = typeof fixedIE == 'function' ? fixedIE('Top', dots[i].Y) : dots[i].Y + PX;
}
}
}
new elastic_trail();
</script>

Do not use anything from the old script or its markup. That will fix the problems with scrolling. As far as the audio, I haven't a clue.


Note: If you want a background image for the page in IE 6, replace foo in this line:


document.write('<style type="text/css">.dot {position: absolute;}body {background: url(foo) fixed;}<\/style>');


with the quoted URL of your background image, ex:


document.write('<style type="text/css">.dot {position: absolute;}body {background: url("some.jpg") fixed;}<\/style>');