//
// 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 = 50;

// 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 = 12;                // die maximale Schriftgröße einer Schneeflocke
var snow_min_size = 5;                // 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 = 0;
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 = 'relative';

        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));