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<style>
body
{
overflow: hidden;
}
</style>
</head>
<body onload="initAnimation();">
</body>
</html>
var MAX_SPEED = 5;
var MIN_SPEED = 10;
var MAX_PATH_WIDTH = 20;
var MIN_PATH_WIDTH = 50;
var MAX_PATH_HEIGHT = getDocumentHeight();
var MIN_PATH_HEIGHT = 100;
var NUM_OBJECTS = 50;
var MAX_SIZE = 32;
var MIN_SIZE = 20;
var snow = [];
/**
* This function is a cross-browser function that gets the document height.
* @return Document height if able to find it, otherwise -1.
* @see http://www.howtocreate.co.uk/tutorials/javascript/browserwindow
*/
function getDocumentHeight()
{
if(typeof(window.innerWidth) == 'number')
{
//Non-IE
return window.innerHeight;
}
else if(document.documentElement && (document.documentElement.clientWidth || document.documentElement.clientHeight))
{
//IE 6+ in 'standards compliant mode'
return document.documentElement.clientHeight;
}
else if( document.body && (document.body.clientWidth || document.body.clientHeight) )
{
//IE 4 compatible
return document.body.clientHeight;
}
else
{
// Unable to find height
return -1;
}
}
/**
* This function is a cross-browser function that gets the document width.
* @return Document width if able to find it, otherwise -1.
* @see http://www.howtocreate.co.uk/tutorials/javascript/browserwindow
*/
function getDocumentWidth()
{
if(typeof(window.innerWidth) == 'number')
{
//Non-IE
return window.innerWidth;
}
else if(document.documentElement && (document.documentElement.clientWidth || document.documentElement.clientHeight))
{
//IE 6+ in 'standards compliant mode'
return document.documentElement.clientWidth;
}
else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) )
{
//IE 4 compatible
return document.body.clientWidth;
}
else
{
// Unable to find wodth
return -1;
}
}
/**
* Returns a random number between min and max.
* @param number min The lower bound of the range.
* @param number max The upper bound of the range.
* @return number A random number between min and max.
*/
function random(min, max)
{
return Math.random() * (max - min) + min;
}
function sinGraph(value, height, waveLength)
{
return height * Math.sin((2 * Math.PI / waveLength) * value);
}
/**
* Create a new snow flake object in the specified starting position
* @param Image imageObj The image object to be used as a snow flake
*/
function SnowFlake(imageObj)
{
var that = this;
this.imageObj = imageObj;
this.interval = null;
this._reset();
}
/**
* Resets teh status of the object with new random values
*/
SnowFlake.prototype._reset = function() {
var size;
this.startX = random(0, getDocumentWidth());
this.startY = -1 * random(0, getDocumentHeight());
this.x = this.startX;
this.y = this.startY;
this.speed = random(MIN_SPEED, MAX_SPEED);
this.pathWidth = random(MIN_PATH_WIDTH, MAX_PATH_WIDTH);
this.pathHeight = random(MIN_PATH_HEIGHT, MAX_PATH_HEIGHT);
size = random(MIN_SIZE, MAX_SIZE);
this.imageObj.width = size;
this.imageObj.height = size;
};
/**
* Starts an infinite animation loop using the given function to move and change the size of the given object.
*/
SnowFlake.prototype._animation = function (funcMoveX, funcSizeWidth) {
this.y += this.speed;
if(this.pathWidth === 0 || this.pathHeight === 0)
{
this.x = funcMoveX(this.y) + this.startX;
}
else
{
this.x = funcMoveX(this.y, this.pathWidth, this.pathHeight) + this.startX;
}
// check if snow flake y value is out of the frame
if(this.y >= window.innerHeight)
{
this._reset();
}
else
{
this.imageObj.style.top = parseInt(this.y, 10) + "px";
}
if(this.x <= window.innerWidth)
{
this.imageObj.style.left = parseInt(this.x, 10) + "px";
}
};
/**
* Starts the animation for this object. To stop the animation call stopAnimation.
*/
SnowFlake.prototype.startAnimation = function()
{
var that = this;
this.interval = setInterval(function(){ that._animation(sinGraph, null); }, 100);
};
/**
* Stops the animation for this object. To start the animation again call startAnimation.
*/
SnowFlake.prototype.stopAnimation = function(){
clearInterval(this.interval);
};
function initAnimation()
{
var object;
var newElementId;
var html = "";
var i;
// add snow flakes images to the html
for(i = 0; i < NUM_OBJECTS; i++)
{
newElementId = "snow" + i;
html += "<img id=\"" + newElementId + "\"src=\"http://www.yagudaev.com/code/snowflake.png\" width=\"32\" height=\"32\" style=\"position: absolute;\" />";
}
document.body.innerHTML += html;
// initialize the animation for the snow flakes
for(i = 0; i < NUM_OBJECTS; i++)
{
object = document.getElementById("snow" + i);
snow.push(new SnowFlake(object));
snow[i].startAnimation();
}
}
Also see: Tab Triggers