El Blog de elSant0 -: Copos de nieve en tu web

Bueno, ya se acercan las navidades y he pensado en darle un toque un poco especial al blog para estas fechas. Ya habréis notado esos copitos de nieve que van cayendo y posándose sobre la base del navegador y pronto veréis algún que otro toque personal más.

Algunos me habéis pedido que explique como conseguir estos efectos, así que vamos a verlo. Pero antes de hacerlo voy a dar las gracias al Escaparate de Rosa, ya que este efecto lo saqué de allí.

Bueno y ahora vamos con el tutorial:

Vamos a Personalizar y luego a Diseño->Edición de HTML y damos a Expandir plantillas de artilugios.

En el código buscamos la siguiente etiqueta:

<head>

Y justo antes pegamos el siguiente script:


<!-- INICIO CODIGO AÑADIDO PARA AÑADIR COPOS DE NIEVE CAYENDO-->
 <script type="text/javascript">
  //<![CDATA[
   /*
   DHTML Snowstorm! OO-style Jascript-based Snow effect
   ----------------------------------------------------
   Version 1.4.20091115 (Previous rev: v1.3.20081215)
   Code by Scott Schiller - http://schillmania.com
   ----------------------------------------------------
   Initializes after body onload() by default (via addEventHandler() call at bottom.)
   To customize properties, edit below or override configuration after this script
   has run (but before body.onload), eg. snowStorm.snowStick = false;
   */
   var snowStorm = null;

   function SnowStorm()
   {
    // --- PROPERTIES ---
    this.flakesMax = 150;          // Limit total amount of snow made (falling + sticking)
    this.flakesMaxActive = 64;         // Limit amount of snow falling at once (less = lower CPU use)
    this.animationInterval = 33;        // Theoretical "miliseconds per frame" measurement. 20 = fast + smooth, but high CPU use. 50 = more conservative, but slower
    this.flakeBottom = null;          // Integer for Y axis snow limit, 0 or null for "full-screen" snow effect
    this.targetElement = null;          // element which snow will be appended to (document body if null/undefined) - can be an element ID string, or a DOM node reference
    this.followMouse = true;          // Snow will change movement with the user's mouse
    this.snowColor = '#fff';          // Don't eat (or use?) yellow snow.
    this.snowCharacter = '&bull;';         // &bull; = bullet, &middot; is square on some systems etc.
    this.snowStick = true;           // Whether or not snow should "stick" at the bottom. When off, will never collect.
    this.useMeltEffect = true;          // When recycling fallen snow (or rarely, when falling), have it "melt" and fade out if browser supports it
    this.useTwinkleEffect = false;         // Allow snow to randomly "flicker" in and out of view while falling
    this.usePositionFixed = false;         // true = snow not affected by window scroll. may increase CPU load, disabled by default - if enabled, used only where supported
    // --- less-used bits ---
    this.flakeLeftOffset = 0;          // amount to subtract from edges of container
    this.flakeRightOffset = 0;          // amount to subtract from edges of container
    this.flakeWidth = 8;           // max pixel width for snow element
    this.flakeHeight = 8;           // max pixel height for snow element
    this.vMaxX = 5;            // Maximum X velocity range for snow
    this.vMaxY = 4;            // Maximum Y velocity range
    this.zIndex = 0;            // CSS stacking order applied to each snowflake
    // --- End of user section ---
    // jslint global declarations
    /*global window, document, navigator, clearInterval, setInterval */
    var addEvent  = (typeof(window.attachEvent)=='undefined'?function(o,evtName,evtHandler) { return o.addEventListener(evtName,evtHandler,false); }:function(o,evtName,evtHandler) { return o.attachEvent('on'+evtName,evtHandler); });
    var removeEvent = (typeof(window.attachEvent)=='undefined'?function(o,evtName,evtHandler) { return o.removeEventListener(evtName,evtHandler,false); }:function(o,evtName,evtHandler) { return o.detachEvent('on'+evtName,evtHandler); });
   
    function rnd(n,min)
    {
     if (isNaN(min)) min = 0;
     return (Math.random()*n)+min;
    }
    function plusMinus(n) { return (parseInt(rnd(2),10)==1?n*-1:n); }

    var s = this;
    var storm = this;
    this.timers = [];
    this.flakes = [];
    this.disabled = false;
    this.active = false;

    var isIE = navigator.userAgent.match(/msie/i);
    var isIE6 = navigator.userAgent.match(/msie 6/i);
    var isOldIE = (isIE && (isIE6 || navigator.userAgent.match(/msie 5/i)));
    var isWin9X = navigator.appVersion.match(/windows 98/i);
    var isiPhone = navigator.userAgent.match(/iphone/i);
    var isBackCompatIE = (isIE && document.compatMode == 'BackCompat');
    var noFixed = ((isBackCompatIE || isIE6 || isiPhone)?true:false);
    var screenX = null;
    var screenX2 = null;
    var screenY = null;
    var scrollY = null;
    var vRndX = null;
    var vRndY = null;
    var windOffset = 1;
    var windMultiplier = 2;
    var flakeTypes = 6;
    var fixedForEverything = false;
    var opacitySupported = (function()
    {
     try   { document.createElement('div').style.opacity = '0.5'; }
     catch (e) { return false; }
     return true;
    })();
    var docFrag = document.createDocumentFragment();
    if (s.flakeLeftOffset === null)  s.flakeLeftOffset = 0;
    if (s.flakeRightOffset === null) s.flakeRightOffset = 0;
    this.meltFrameCount = 20;
    this.meltFrames = [];
    for (var i=0; i<this.meltFrameCount; i++) this.meltFrames.push(1-(i/this.meltFrameCount));
    this.randomizeWind = function()
    {
     vRndX = plusMinus(rnd(s.vMaxX,0.2));
     vRndY = rnd(s.vMaxY,0.2);
     if (this.flakes)
     {
      for (var i=0; i<this.flakes.length; i++)
      {
       if (this.flakes[i].active) this.flakes[i].setVelocities();
      }
     }
    };

    this.scrollHandler = function()
    {
    // "attach" snowflakes to bottom of window if no absolute bottom value was given
     scrollY = (s.flakeBottom?0:parseInt(window.scrollY||document.documentElement.scrollTop||document.body.scrollTop,10));
     if (isNaN(scrollY)) scrollY = 0; // Netscape 6 scroll fix
     if (!fixedForEverything && !s.flakeBottom && s.flakes)
     {
      for (var i=s.flakes.length; i--;)
      {
       if (s.flakes[i].active === 0) s.flakes[i].stick();
      }
     }
    };

    this.resizeHandler = function()
    {
     if (window.innerWidth || window.innerHeight)
     {
      screenX = window.innerWidth-(!isIE?16:2)-s.flakeRightOffset;
      screenY = (s.flakeBottom?s.flakeBottom:window.innerHeight);
     }
     else
     {
      screenX = (document.documentElement.clientWidth||document.body.clientWidth||document.body.scrollWidth)-(!isIE?8:0)-s.flakeRightOffset;
      screenY = s.flakeBottom?s.flakeBottom:(document.documentElement.clientHeight||document.body.clientHeight||document.body.scrollHeight);
     }
     screenX2 = parseInt(screenX/2,10);
    };

    this.resizeHandlerAlt = function()
    {
     screenX = s.targetElement.offsetLeft+s.targetElement.offsetWidth-s.flakeRightOffset;
     screenY = s.flakeBottom?s.flakeBottom:s.targetElement.offsetTop+s.targetElement.offsetHeight;
     screenX2 = parseInt(screenX/2,10);
    };

    this.freeze = function()
    {
     // pause animation
     if (!s.disabled) s.disabled = 1;
     else    return false;
     for (var i=s.timers.length; i--;) clearInterval(s.timers[i]);   
    };

    this.resume = function()
    {
     if (s.disabled)  s.disabled = 0;
     else    return false;
     s.timerInit();
    };

    this.toggleSnow = function()
    {
     if (!s.flakes.length) s.start();  // first run
     else
     {
      s.active = !s.active;
      if (s.active)
      {
       s.show();
       s.resume();
      }
      else
      {
       s.stop();
       s.freeze();
      }
     }
    };

    this.stop = function()
    {
     this.freeze();
     for (var i=this.flakes.length; i--;) this.flakes[i].o.style.display = 'none';
     removeEvent(window,'scroll',s.scrollHandler);
     removeEvent(window,'resize',s.resizeHandler);
     if (!isOldIE)
     {
      removeEvent(window,'blur',s.freeze);
      removeEvent(window,'focus',s.resume);
     }
    };
    this.show = function() { for (var i=this.flakes.length; i--;) this.flakes[i].o.style.display = 'block'; };
    this.SnowFlake = function(parent,type,x,y)
    {
     var s = this;
     var storm = parent;
     this.type = type;
     this.x = x||parseInt(rnd(screenX-20),10);
     this.y = (!isNaN(y)?y:-rnd(screenY)-12);
     this.vX = null;
     this.vY = null;
     this.vAmpTypes = [1,1.2,1.4,1.6,1.8]; // "amplification" for vX/vY (based on flake size/type)
     this.vAmp = this.vAmpTypes[this.type];
     this.melting = false;
     this.meltFrameCount = storm.meltFrameCount;
     this.meltFrames = storm.meltFrames;
     this.meltFrame = 0;
     this.twinkleFrame = 0;
     this.active = 1;
     this.fontSize = (10+(this.type/5)*10);
     this.o = document.createElement('div');
     this.o.innerHTML = storm.snowCharacter;
     this.o.style.color = storm.snowColor;
     this.o.style.position = (fixedForEverything?'fixed':'absolute');
     this.o.style.width = storm.flakeWidth+'px';
     this.o.style.height = storm.flakeHeight+'px';
     this.o.style.fontFamily = 'arial,verdana';
     this.o.style.overflow = 'hidden';
     this.o.style.fontWeight = 'normal';
     this.o.style.zIndex = storm.zIndex;
     docFrag.appendChild(this.o);

     this.refresh = function()
     {
      if (isNaN(s.x) || isNaN(s.y)) return false; // safety check
      s.o.style.left = s.x+'px';
      s.o.style.top = s.y+'px';
     };
     this.stick = function()
     {
      if (noFixed || (storm.targetElement != document.documentElement && storm.targetElement != document.body)) s.o.style.top = (screenY+scrollY-storm.flakeHeight)+'px';
      else
      {
       if (storm.flakeBottom) s.o.style.top = storm.flakeBottom+'px';
       else
       {
        s.o.style.display = 'none';
        s.o.style.top = 'auto';
        s.o.style.bottom = '0px';
        s.o.style.position = 'fixed';
        s.o.style.display = 'block';
       }
      }
     };
     this.vCheck = function()
     {
      if (s.vXgt;=0 && s.vX<0.2)  s.vX = 0.2;
      else if (s.vX<0 && s.vX>-0.2) s.vX = -0.2;
      if (s.vY>=0 && s.vY<0.2)  s.vY = 0.2;
     };
     this.move = function()
     {
      var vX = s.vX*windOffset;
      s.x += vX;
      s.y += (s.vY*s.vAmp);
      if (s.x >= screenX || screenX-s.x < storm.flakeWidth) s.x = 0;// X-axis scroll check
      else if (vX < 0 && s.x-storm.flakeLeftOffset<0-storm.flakeWidth) s.x = screenX-storm.flakeWidth-1; // flakeWidth;
      s.refresh();
      var yDiff = screenY+scrollY-s.y;
      if (yDiff<storm.flakeHeight)
      {
       s.active = 0;
       if (storm.snowStick) s.stick();
       else     s.recycle();
      }
      else
      {
       if (storm.useMeltEffect && s.active && s.type < 3 && !s.melting && Math.random()>0.998)
       {
        // ~1/1000 chance of melting mid-air, with each frame
        s.melting = true;
        s.melt();
        // only incrementally melt one frame
        // s.melting = false;
       }
       if (storm.useTwinkleEffect)
       {
        if (!s.twinkleFrame)
        {
         if (Math.random()>0.9) s.twinkleFrame = parseInt(Math.random()*20,10);
        }
        else
        {
         s.twinkleFrame--;
         s.o.style.visibility = (s.twinkleFrame && s.twinkleFrame%2===0?'hidden':'visible');
        }
       }
      }
     };
     this.animate = function()
     {
      // main animation loop
      // move, check status, die etc.
      s.move();
     };
     this.setVelocities = function()
     {
      s.vX = vRndX+rnd(storm.vMaxX*0.12,0.1);
      s.vY = vRndY+rnd(storm.vMaxY*0.12,0.1);
     };

     this.setOpacity = function(o,opacity)
     {
      if (!opacitySupported) return false;
      o.style.opacity = opacity;
     };

     this.melt = function()
     {
      if (!storm.useMeltEffect || !s.melting) s.recycle();
      else
      {
       if (s.meltFrame < s.meltFrameCount)
       {
        s.meltFrame++;
        s.setOpacity(s.o,s.meltFrames[s.meltFrame]);
        s.o.style.fontSize = s.fontSize-(s.fontSize*(s.meltFrame/s.meltFrameCount))+'px';
        s.o.style.lineHeight = storm.flakeHeight+2+(storm.flakeHeight*0.75*(s.meltFrame/s.meltFrameCount))+'px';
       }
       else s.recycle();
      }
     };

     this.recycle = function()
     {
      s.o.style.display = 'none';
      s.o.style.position = (fixedForEverything?'fixed':'absolute');
      s.o.style.bottom = 'auto';
      s.setVelocities();
      s.vCheck();
      s.meltFrame = 0;
      s.melting = false;
      s.setOpacity(s.o,1);
      s.o.style.padding = '0px';
      s.o.style.margin = '0px';
      s.o.style.fontSize = s.fontSize+'px';
      s.o.style.lineHeight = (storm.flakeHeight+2)+'px';
      s.o.style.textAlign = 'center';
      s.o.style.verticalAlign = 'baseline';
      s.x = parseInt(rnd(screenX-storm.flakeWidth-20),10);
      s.y = parseInt(rnd(screenY)*-1,10)-storm.flakeHeight;
      s.refresh();
      s.o.style.display = 'block';
      s.active = 1;
     };
     this.recycle(); // set up x/y coords etc.
     this.refresh();
    };

    this.snow = function()
    {
     var active = 0;
     var used = 0;
     var waiting = 0;
     var flake = null;
     for (var i=s.flakes.length; i--;)
     {
      if (s.flakes[i].active == 1)
      {
       s.flakes[i].move();
       active++;
      }
      else if (s.flakes[i].active === 0) used++;
      else waiting++;
      if (s.flakes[i].melting) s.flakes[i].melt();
     }
     if (active<s.flakesMaxActive)
     {
      flake = s.flakes[parseInt(rnd(s.flakes.length),10)];
      if (flake.active === 0) flake.melting = true;
     }
    };

    this.mouseMove = function(e)
    {
     if (!s.followMouse) return true;
     var x = parseInt(e.clientX,10);
     if (x<screenX2) windOffset = -windMultiplier+(x/screenX2*windMultiplier);
     else
     {
      x -= screenX2;
      windOffset = (x/screenX2)*windMultiplier;
     }
    };
    this.createSnow = function(limit,allowInactive)
    {
     for (var i=0; i<limit; i++)
     {
      s.flakes[s.flakes.length] = new s.SnowFlake(s,parseInt(rnd(flakeTypes),10));
      if (allowInactive || i>s.flakesMaxActive) s.flakes[s.flakes.length-1].active = -1;
     }
     storm.targetElement.appendChild(docFrag);
    };

    this.timerInit = function()
    {
     s.timers = (!isWin9X?[setInterval(s.snow,s.animationInterval)]:[setInterval(s.snow,s.animationInterval*3),setInterval(s.snow,s.animationInterval)]);
    };

    this.init = function()
    {
     s.randomizeWind();
     s.createSnow(s.flakesMax); // create initial batch
     addEvent(window,'resize',s.resizeHandler);
     addEvent(window,'scroll',s.scrollHandler);
     if (!isOldIE)
     {
      addEvent(window,'blur',s.freeze);
      addEvent(window,'focus',s.resume);
     }
     s.resizeHandler();
     s.scrollHandler();
     if (s.followMouse) addEvent(document,'mousemove',s.mouseMove);
     s.animationInterval = Math.max(20,s.animationInterval);
     s.timerInit();
    };
   
    var didInit = false;
    this.start = function(bFromOnLoad)
    {
     if (!didInit)   didInit = true;
     else if (bFromOnLoad) return true; // already loaded and running
     if (typeof s.targetElement == 'string')
     {
      var targetID = s.targetElement;
      s.targetElement = document.getElementById(targetID);
      if (!s.targetElement) throw new Error('Snowstorm: Unable to get targetElement "'+targetID+'"');
     }
     if (!s.targetElement) s.targetElement = (!isIE?(document.documentElement?document.documentElement:document.body):document.body);
     if (s.targetElement != document.documentElement && s.targetElement != document.body) s.resizeHandler = s.resizeHandlerAlt; // re-map handler to get element instead of screen dimensions
     s.resizeHandler(); // get bounding box elements
     s.usePositionFixed = (s.usePositionFixed && !noFixed); // whether or not position:fixed is supported
     fixedForEverything = s.usePositionFixed;
     if (screenX && screenY && !s.disabled)
     {
      s.init();
      s.active = true;
     }
    };
    function doStart() { s.start(true); }
    if (document.addEventListener)
    {
     // safari 3.0.4 doesn't do DOMContentLoaded, maybe others - use a fallback to be safe.
     document.addEventListener('DOMContentLoaded',doStart,false);
     window.addEventListener('load',doStart,false);
    }
    else addEvent(window,'load',doStart);
   } 
   snowStorm = new SnowStorm();
  //]]>
 </script>
 <!-- FIN CODIGO AÑADIDO PARA AÑADIR COPOS DE NIEVE CAYENDO-->

Con eso basta, pero también podemos cambiar algunos aspectos de configuración como el número de copos. Para ello buscamos dentro del nuevo código añadido la siguiente línea:
```
this.flakesMax = 150;
```
Salimos guardando los cambios y ya podemos comprobar el efecto en el blog.

Y eso es todo. Es bastante fácil.

Salu2,
elSant0

3 comentarios:

rafaourense dijo...: Nuestra maravillosa asturiana, veo que tienes buen gusto en tu seguimiento de blog.
Mola la nieve en estas fechas.
saludos a Rosa.; 9 de diciembre de 2010, 17:04
Anónimo dijo...: No me sirve; 28 de noviembre de 2011, 23:51
elSant0 dijo...: Anónimo(28/11/11)@ ¿Por qué? ¿Obtienes algún error?; 8 de diciembre de 2011, 10:53

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