Laberecke » script schneefall

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<!DOCTYPE HTML><html>
 
<head>
<title>Schneeflocken</title>
<meta charset="utf-8">
 
<style type="text/css">
.snowflake {
position:absolute;
top:0px;
left:0px;
 
color:#CCC; /* Farbe für Alternativtext */
}
</style>
 
<script type="text/javascript">
/*<![CDATA[*/
 
var snowProperties = {
// Adresse der Schneeflocken-Grafik:
flakeImage : 'http://files.homepagemodules.de/b2001010/a_1421_a944bc65.gif',
// Alternativ-Text, falls Grafik nicht gefunden:
flakeText : '*',
 
// maximale Abweichung von der Standard-Bildgröße in Prozent [0..1]
// z.B.: 0 = keine, 50 = +-50%, 100 = +-100% (doppelt so groß bzw. nicht mehr zu sehen)
deviation : 50,
 
flakeWidth : 20, // Breite einer Schneeflocke
flakeHeight : 23, // Höhe einer Schneeflocke
 
animSpeed : 75, // Intervall für Ausführung der Animations in ms
stepDown : 2, // Pixel nach unten pro Animations-Schritt
amplitude : 10, // maximale Pendelbewegungen seitwärts in Pixeln
period : 12.5, // Länge für eine komplette Pendelbewegung
 
amountStart : Math.ceil(window.innerWidth*0.0025), // Anzahl der zu ladenden Schneeflocken pro Zeile
snowLine : Math.round(window.innerHeight * 0.8), // maximale Höhe, welche die Schneeflocken zurücklegen
sizeBottom : 2 // minimale Größe einer Schneeflocke am Ende in Prozent
}
 
function snowFlake() {
var that = this;
 
this.deviation = ((Math.random() * 2) - 1) * (snowProperties.deviation/100);
this.width = snowProperties.flakeWidth * (1 + this.deviation);
this.height = snowProperties.flakeHeight * (1 + this.deviation);
 
this.posX = Math.floor((Math.random() * (window.innerWidth - this.width - Math.abs(this.deviation) ) ) + 1);
this.posY = ((-1) * this.height) - Math.floor((Math.random() * (2*this.height) ) + 1);
 
this.decrWidth = ( this.width - ( this.width * (snowProperties.sizeBottom/100) ) ) // (Anfangsbreite - Endbreite)
/ (snowProperties.snowLine - (this.height * 3));
this.decrHeight = ( this.height - ( this.height * (snowProperties.sizeBottom/100) ) ) // (Anfangshöhe - Endhöhe)
/ (snowProperties.snowLine - (this.height * 3));
 
this.flake;
this.init = function() {
// HTML-Element für Schneeflocke erzeugen:
this.flake = document.createElement('img');
// Attribute des HTML-Elementes initialisieren:
this.flake.setAttribute( 'name', 'snowflake');
this.flake.setAttribute( 'alt', snowProperties.flakeText);
this.flake.setAttribute( 'class', 'snowflake');
this.flake.setAttribute( 'src', snowProperties.flakeImage);
// Element in Seite einbinden:
document.getElementsByTagName('body')[0].appendChild(this.flake);
 
this.flake.style.width = this.width + 'px';
this.flake.style.height = this.height + 'px';
this.flake.style.top = this.posY + 'px';
this.flake.style.left = this.posX + 'px';
}
this.init();
 
this.remove = function() {
document.getElementsByTagName('body')[0].removeChild(this.flake);
}
 
 
this.fallDown = function() {
this.posY += snowProperties.stepDown;
this.flake.style.top = this.posY + 'px';
 
var newPosition = parseFloat(this.posX) +
snowProperties.amplitude *
Math.sin( (1/snowProperties.period) * (this.posY - this.deviation) );
this.flake.style.left = newPosition + 'px';
 
this.width -= this.decrWidth;
this.height -= this.decrHeight;
this.flake.style.width = this.width + 'px';
this.flake.style.height = this.height + 'px';
}
}
 
 
function snowFall() {
var that = this;
 
this.flakes;
 
var interval;
var timeout;
 
var loadRange;
var loadTimer;
var totalAmount;
var countLoaded = 0; // Anzahl geladener Schneeflocken
 
this.init = function() {
totalAmount = snowProperties.amountStart *
Math.round( snowProperties.snowLine / (snowProperties.flakeHeight * 1.5 * 2) );
 
this.flakes = new Array(totalAmount);
loadRange = snowProperties.amountStart; // this.flakes.length * (snowProperties.amountStart/100);
 
for (var i = 0; i < loadRange; i++) {
this.flakes[i] = new snowFlake();
this.flakes[i].flake.style.display = 'none';
countLoaded = i + 1;
}
 
// (Durchschnittliche Fallhöhe bis Bildrand) * (Zeitschritte, die bis dahin vergingen):
loadTimer = (snowProperties.flakeHeight * 1.5 * 2) * (snowProperties.animSpeed / snowProperties.stepDown);
timeout = window.setTimeout( function() { that.loadAsync(); }, loadTimer);
}
this.init();
 
this.loadAsync = function() {
var loadMore = false;
for (var i = 0; i < loadRange; i++) {
if ( (countLoaded < this.flakes.length) && (this.flakes[countLoaded] == null) ) {
this.flakes[countLoaded++] = new snowFlake();
}
else {
break;
}
loadMore = true;
}
if (loadMore) {
timeout = window.setTimeout( function() { that.loadAsync(); }, loadTimer);
}
}
 
this.show = function() {
for (var i = 0; i < this.flakes.length; i++) {
if (this.flakes[i] != null) {
this.flakes[i].flake.style.display = 'block';
}
}
}
this.hide = function() {
for (var i = 0; i < this.flakes.length; i++) {
if (this.flakes[i] != null) {
this.flakes[i].flake.style.display = 'none';
}
}
}
 
this.startAnimation = function() {
interval = window.setInterval( function() { that.play(); } , snowProperties.animSpeed);
this.show();
}
this.stopAnimation = function() {
window.clearInterval(interval);
this.hide();
}
 
this.play = function() {
for (var i = 0; i < this.flakes.length; i++) {
if (this.flakes[i] != null) {
if (this.flakes[i].posY > snowProperties.snowLine) {
this.flakes[i].remove(); // alte Schneeflocke entfernen
this.flakes[i] = new snowFlake(); // neue Schneeflocke generieren
}
this.flakes[i].fallDown();
}
}
}
}
 
 
function letTheSnowFall() {
var fallingSnow = new snowFall();
fallingSnow.startAnimation();
 
//window.setTimeout( function(){ fallingSnow.hide(); }, 10000);
//window.setTimeout( function(){ fallingSnow.show(); }, 44000);
window.setTimeout( function(){ fallingSnow.stopAnimation(); }, 45000); // Dauer der Animation
}
 
/*]]>*/
</script>
</head>
 
<body onLoad="letTheSnowFall();">
</body>
 
</html>
 