var op = new Array(0, 0, 0);
var od = new Array(0, 0, 0);

var step = 10;
var wait = 20;

function setOpacity(obj, opacity) {
  opacity = (opacity == 100) ? 99.999 : opacity;
  obj.style.filter = "alpha(opacity:"+opacity+")";
  obj.style.KHTMLOpacity = opacity / 100;
  obj.style.MozOpacity = opacity / 100;
  obj.style.opacity = opacity / 100;
}

function fadeIn(objId, arrId) {
  if(od[arrId] == 0) {
    od[arrId] = 1;
    fadeInObj(objId, arrId);
  }
}

function fadeOut(objId, arrId) {
  if(od[arrId] == 1) {
    od[arrId] = 0;
    fadeOutObj(objId, arrId);
  }
}

function fadeInObj(objId, arrId) {
  if(document.getElementById) {
    obj = document.getElementById(objId);
    if(op[arrId] < 100 && od[arrId] == 1) {
      setOpacity(obj, op[arrId]);
      op[arrId] += step;
      window.setTimeout("fadeInObj('"+objId+"',"+arrId+")", wait);
    } else {
      setOpacity(obj, 100);
    }
  }
}

function fadeOutObj(objId, arrId) {
  if(document.getElementById) {
    obj = document.getElementById(objId);
    if(op[arrId] >= 0 && od[arrId] == 0) {
      setOpacity(obj, op[arrId]);
      op[arrId] -= step;
      window.setTimeout("fadeOutObj('"+objId+"',"+arrId+")", wait);
    }
  }
}

function initImage() {
  imageId = "p1";
  image = document.getElementById(imageId);
  setOpacity(image, 0);
  image.style.visibility = "visible";
  imageId = "p2";
  image = document.getElementById(imageId);
  setOpacity(image, 0);
  image.style.visibility = "visible";
  imageId = "p3";
  image = document.getElementById(imageId);
  setOpacity(image, 0);
  image.style.visibility = "visible";
}

window.onload = function() {
  initImage();
}