var rand1 = 0;
var useRand = 0;

rndImage = new Array;
rndImage[1] = new Image();
rndImage[1].src = "img/dier_1.gif";
rndImage[2] = new Image();
rndImage[2].src = "img/dier_2.gif";
rndImage[3] = new Image();
rndImage[3].src = "img/dier_3.gif";

function swapPic() {
	var imgnum = rndImage.length - 1;
	do {
		var randnum = Math.random();
		rand1 = Math.round((imgnum - 1) * randnum) + 1;
	} while (rand1 == useRand);
	useRand = rand1;
	document.imgTopbar.src = rndImage[useRand].src;
}