var layerObj = 'lightDiv';

function dimmer(val){
	if (val){
		opacity('lightDiv' , 75, 0, 1000);
	} else {
		opacity('lightDiv' , 0, 75, 1000);
	}
	
}

function opacity(id, opacStart, opacEnd, millisec) {
    //speed for each frame
    var speed = Math.round(millisec / 100);
    var timer = 0;
    //determine the direction for the blending, if start and end are the same nothing happens
    if(opacStart > opacEnd) {
        for(i = opacStart; i >= opacEnd; i--) {
            setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
            timer++;
        }
            setTimeout("hideDiv('"+id+"')",(timer * speed));
    } else if(opacStart < opacEnd) {
        for(i = opacStart; i <= opacEnd; i++)
            {
            setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
            timer++;
        }
	document.getElementById(id).style.visibility = 'visible'; 

    }
}

//change the opacity for different browsers
function changeOpac(opacity, id) {
    var object = document.getElementById(id).style;
    object.opacity = (opacity / 100);
    object.MozOpacity = (opacity / 100);
    object.KhtmlOpacity = (opacity / 100);
    object.filter = "alpha(opacity=" + opacity + ")";
}

function hideDiv(id){
    document.getElementById(id).style.visibility = 'hidden'; 
}