Java script的问题

网游天下

这是我论坛的java script,请问要修改或增加什么才可以让雪花在一开始时分期降落下来,而不是一次过呢??

  // This JavaScript code can be freely redistributed
  // as long as this copyright notice is keept unchanged.
  // This code is used on AS-IS basis and
  // you use it on your own risk. Author of this code
  // is not responsible for any damage that this
  // code may make.
  //
  // JS Snow v0.2
  // finished on 11-10-1999 23:04 in Zagreb, Croatia.
  // modified on 06-12-2005 11:20 in Zagreb, Croatia.
  //
  // Copyright 1999,2005 Altan d.o.o.
  // http://www.altan.hr/snow/index.html
  // E-mail: snow@altan.hr
  
  var no = 10; // snow number

  var dx, xp, yp;    // coordinate and position variables
  var am, stx, sty;  // amplitude and step variables
  var i, doc_width = 800, doc_height = 600;
  
  doc_width = document.body.clientWidth;
  doc_height = document.body.clientHeight;

  dx = new Array();
  xp = new Array();
  yp = new Array();
  am = new Array();
  stx = new Array();
  sty = new Array();
  
  for (i = 0; i < no; ++ i) {  
    dx = 0;                        // set coordinate variables
    xp = Math.random()*(doc_width-50);  // set position variables
    yp = Math.random()*doc_height;
    am = Math.random()*20;         // set amplitude variables
    stx = 0.02 + Math.random()/10; // set step variables
    sty = 0.7 + Math.random();     // set step variables
    if (i == 0) {
      document.write("<div id=\"dot"+ i +"\" style=\"POSITION: absolute; Z-INDEX: "+ i +"; VISIBILITY: visible; TOP: 15px; LEFT: 15px;\"><a href=\"http://inet.hr/\"><img src=\"http://www.altan.hr/snow/dott.gif\" border=\"0\"></a></div>");
    } else {
      document.write("<div id=\"dot"+ i +"\" style=\"POSITION: absolute; Z-INDEX: "+ i +"; VISIBILITY: visible; TOP: 15px; LEFT: 15px;\"><img src=\"http://www.altan.hr/snow/dott.gif\" border=\"0\"></div>");
    }
  }

  function snow() {
    for (i = 0; i < no; ++ i) {  // iterate for every dot
      yp += sty;
      if (yp > doc_height-50) {
        xp = Math.random()*(doc_width-am-30);
        yp = 0;
        stx = 0.02 + Math.random()/10;
        sty = 0.7 + Math.random();
        doc_width = document.body.clientWidth;
        doc_height = document.body.clientHeight;
      }
      dx += stx;
      document.getElementById("dot"+i).style.top = yp;
      document.getElementById("dot"+i).style.left = xp + am*Math.sin(dx);
    }
    setTimeout("snow()", 10);
  }

  snow();

[ 本帖最后由 网游天下 于 25-3-2006 12:05 AM 编辑 ]