//
// Opacity functions courtesy of http://brainerror.net/scripts_js_blendtrans.php
//
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++;
		}
	} else if(opacStart < opacEnd) {
		for(i = opacStart; i <= opacEnd; i++)
			{
			setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
			timer++;
		}
	}
}

//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 shiftOpacity(id, millisec) {
	//if an element is invisible, make it visible, else make it ivisible
	if(document.getElementById(id).style.opacity == 0) {
		opacity(id, 0, 100, millisec);
	} else {
		opacity(id, 100, 0, millisec);
	}
}

function blendimage(divid, imageid, imagefile, millisec) {
	var speed = Math.round(millisec / 100);
	var timer = 0;
	
	//set the current image as background
	document.getElementById(divid).style.backgroundImage = "url(" + document.getElementById(imageid).src + ")";
	
	//make image transparent
	changeOpac(0, imageid);
	
	//make new image
	document.getElementById(imageid).src = imagefile;

	//fade in image
	for(i = 0; i <= 100; i++) {
		setTimeout("changeOpac(" + i + ",'" + imageid + "')",(timer * speed));
		timer++;
	}
}

function currentOpac(id, opacEnd, millisec) {
	//standard opacity is 100
	var currentOpac = 100;
	
	//if the element has an opacity set, get it
	if(document.getElementById(id).style.opacity < 100) {
		currentOpac = document.getElementById(id).style.opacity * 100;
	}

	//call for the function that changes the opacity
	opacity(id, currentOpac, opacEnd, millisec)
}

//
// Select random image
//
function selectRandomImage()
{
	var imagenumber = 3;
	var randomnumber = Math.random();
	var rand1 = Math.round((imagenumber-1) * randomnumber);
	var images = new Array();
	images[0] = "images/splash_1.jpg";
	images[1] = "images/splash_2.jpg";
	images[2] = "images/splash_3.jpg";
	return images[rand1];
}

//
// Transition function
//
var FADE_DURATION = 2500;
function fadeToBackgroundAndRedirect()
{
	// Fade image
	opacity('splashImage', 100, 0, FADE_DURATION);
	
	// Redirect to home page after fade is complete
	setTimeout("document.location.href = 'home.html'", FADE_DURATION+50);
}