//
// Copyright (C) 2008 by Fabian Schlieper
// Schnee v1.2
// http://www.fabi.me/
// Ohne dieses Copyright darf dieser Code nicht verwendet werden!
//

// die ID des HTML-Elements, in dem es schneien soll
var snow_area_id = 'winter';

// maximale Anzahl der sichtbaren Schneeflocken
var snow_flake_count = 100;

// die verschiedenen Farbe, die die Schneeflocken haben sollen
var snow_colors = new Array('#AAAACC','#DDDDFF','#CCCCDD','#F3F3F3','#F0FFFF');

// die Schriftarten, aus denen die Schneeflocken bestehen sollen
var snow_fonts  = new Array('Arial Black', 'Arial Narrow', 'Times', 'Comic Sans MS');

var snow_char = '*';        // das Zeichen, das als Schneeflocke verwendet wird
var snow_gravity = 0.8;     // wie schnell die Schneeflocken fallen
var snow_max_size = 22;     // die maximale Schriftgröße einer Schneeflocke
var snow_min_size = 10;     // die minimale Schriftgröße einer Schneeflocke

var snow_init_delay = 50;   // Verzögerungszeit in Millisekunden, bevor es zu schneien anfängt


// ######################################################################
// HIER ENDET DIE KONFIGURATION. ÄNDERUNGEN IM FOLGENDEN SETZEN JAVSCRIPT-KENNTNISSE VORAUS
// ######################################################################

var snow_init_time = 5;
var snowflakes = new Array();
var snow_area_el = null;

function createSnowflakes()
{
    var style = 'position:absolute; top:-' + snow_max_size + 'px; z-index:99;';
    for (var i = 0; i <= snow_flake_count; i++)
        document.write('<sp' + 'an id="snwflk' + i + '" style="' + style + '">' + snow_char + '</sp' + 'an>');
}

function randInt(range) { return Math.floor(Math.random() * range); }

function initSnow()
{   
    snow_area_el = document.getElementById(snow_area_id);
    
    // reapeat until we have the snow_area_el
    if(!snow_area_el || snow_area_el.offsetWidth <= snow_max_size || snow_area_el.offsetHeight <= snow_max_size) {
        // after 5 secs cancel
        if(snow_init_time < 5000)
            window.setTimeout('initSnow()', 50);
            
        snow_init_time += 50;
        return;
    }
    
    // offest fix
    snow_area_el.style.position = 'absolute';   

            
    for (var i = 0; i <= snow_flake_count; i++)
    {   
        snowflakes[i] = document.getElementById('snwflk' + i);
        
        snowflakes[i].size = (randInt(snow_max_size - snow_min_size) + snow_min_size);      
        snowflakes[i].posx = -snowflakes[i].size;
        snowflakes[i].posy = -snowflakes[i].size;
        snowflakes[i].sink = (snow_gravity * snowflakes[i].size / snow_min_size);
        snowflakes[i].wobamp = (Math.random() * (snowflakes[i].size));
        snowflakes[i].wob = 0.0;
        snowflakes[i].wobspeed = (0.03 + Math.random() / 10.0);
        
        snowflakes[i].style.fontFamily = snow_fonts[randInt(snow_fonts.length)];
        snowflakes[i].style.fontSize = snowflakes[i].size + 'px';
        snowflakes[i].style.color = snow_colors[randInt(snow_colors.length)];
    }
    
    window.setInterval('updateSnow()', 50);
}

function updateSnow()
{
    var bl = snow_area_el.offsetLeft;
    var bt = snow_area_el.offsetTop;
    var bw = snow_area_el.offsetWidth;
    var bh = snow_area_el.offsetHeight; 
    var br = bl + bw;   
    var bb = bt + bh;   
        
    for (var i = 0; i <= snow_flake_count; i++)
    {
        snowflakes[i].wob += snowflakes[i].wobspeed;
        var x = snowflakes[i].posx + (snowflakes[i].wobamp * Math.sin(snowflakes[i].wob));      
        snowflakes[i].posy += snowflakes[i].sink;
        
        snowflakes[i].style.left = Math.round(x) + 'px';
        snowflakes[i].style.top = Math.round(snowflakes[i].posy) + 'px';
        
        var s = snowflakes[i].size;     
        // check bounds
        if (snowflakes[i].posy > (bb - s) || x < bl || x  > (br - s))
        {
            snowflakes[i].posx = bl + s + randInt(bw - (3 * s));
            
            if(snowflakes[i].posy < 0)
                snowflakes[i].posy = bt + randInt(bh - 2 * s);
            else
                snowflakes[i].posy = bt;
        }
    }
}

// Schnee initialisieren
createSnowflakes();
window.setTimeout('initSnow()', Math.max(50, snow_init_delay));