var oParallax, wHalfParallax, hHalfParallax, scaleParallax; 
var oChildren, wHalfChildren, hHalfChildren;
var lParallax, tParallax;

function load(sDiv, iScale)
{
    var i;
    oParallax = document.getElementById(sDiv);
    oParallax.onmousemove = parallax_move;
    oParallax.ondragstart = function() { return false; /* per IE */ }
    wHalfParallax = parseInt(oParallax.style.width) / 2;
    hHalfParallax = parseInt(oParallax.style.height) / 2;
    lParallax = parseInt(oParallax.style.left)
    tParallax = parseInt(oParallax.style.top)
    scaleParallax = iScale;

    oChildren = oParallax.getElementsByTagName("div");
    if (oChildren.length <= 0) { alert("Errore su configurazione myParallax!"); }
    wHalfChildren = parseInt(oChildren[0].style.width) / 2;
    hHalfChildren = parseInt(oChildren[0].style.height) / 2;

    for (i=0; i<oChildren.length; i++)
    {
        iLeft = wHalfParallax - wHalfChildren ;
        iTop = hHalfParallax - hHalfChildren ;

        oChildren[i].style.marginLeft = iLeft+"px";
        oChildren[i].style.marginTop = iTop+"px";
    }
}

function parallax_move(event)
{
    var i, iLeft, iTop;
    if (!event) {event = window.event; /* per IE */ }

    for (i=0; i<oChildren.length; i++)
    {
        iLeft = wHalfParallax - wHalfChildren + ((wHalfParallax - event.clientX) * scaleParallax * (oChildren[i].style.zIndex));
        iTop = hHalfParallax - hHalfChildren + ((hHalfParallax - event.clientY) * scaleParallax * (oChildren[i].style.zIndex));

        iLeft = iLeft + lParallax;
        iTop = iTop + tParallax;

        oChildren[i].style.marginLeft=iLeft+"px";
        oChildren[i].style.marginTop= iTop+"px";
    }
}