/* set order of cars
0 rolls
1 eclass
2 sclass
3 sprinter
4 vclass
#*/

var cars = new Array('rolls', 'eclass', 'sclass', 'vclass', 'sprinter');

var carpos = 0;

function getObj(name)
{
  if (document.getElementById)
  {
  	this.obj = document.getElementById(name);
	this.style = document.getElementById(name).style;
  }
}

  
function nextcar(){	// set visibility of current(old) car to hidden
	var oldcar = new getObj(cars[carpos]);
	oldcar.style.visibility = "hidden";
	carpos++;
	if (carpos > cars.length - 1){
	   carpos = 0;
	   }
	// set visibility of next car to visible	
	var newcar = new getObj(cars[carpos]);
	newcar.style.visibility = "visible";
	return carpos;
	}
	
function prevcar(){	// set visibility of current car to hidden	//
	var oldcar = new getObj(cars[carpos]);
	oldcar.style.visibility = "hidden";
	if (carpos -1 < 0){
	   carpos = cars.length -1;}
	else {
		carpos = carpos -1;}

	var newcar = new getObj(cars[carpos]);	
	newcar.style.visibility = "visible";
	return carpos;	
	}
	//alert('old car= ' + cars[carpos] +' num= ' + carpos);
	//alert('new car= ' + cars[carpos] +' num= ' + carpos);