var browser     = '';
var version     = '';
var entrance    = '';
var cond        = '';
// BROWSER
if (browser == ''){
if (navigator.appName.indexOf('Microsoft') != -1)
browser = 'IE'
else if (navigator.appName.indexOf('Netscape') != -1)
browser = 'Netscape'
else browser = 'NN';
}
// VERSION?
if (version == ''){
version= navigator.appVersion;
paren = version.indexOf('(');
whole_version = navigator.appVersion.substring(0,paren-1);
version         = parseInt(whole_version);
}
// BROWSER & VERSION
if (browser == 'IE' && version >= 4) entrance = 'yes';
if (browser == 'IE' && version < 4) entrance = 'no';
if (browser == 'Netscape' && version >= 2.02) entrance = 'yes';
if (browser == 'Netscape' && version < 2.02) entrance = 'no';
if (entrance=='yes'){
name0a=new Image;name0a.src="button_01.gif";
name0b=new Image;name0b.src="button_01_down.gif";
name0c=new Image;name0c.src="button_01_down.gif";
name1a=new Image;name1a.src="button_02.gif";
name1b=new Image;name1b.src="button_02_down.gif";
name1c=new Image;name1c.src="button_02_down.gif";
name2a=new Image;name2a.src="button_03.gif";
name2b=new Image;name2b.src="button_03_down.gif";
name2c=new Image;name2c.src="button_03_down.gif";
name3a=new Image;name3a.src="button_04.gif";
name3b=new Image;name3b.src="button_04_down.gif";
name3c=new Image;name3c.src="button_04_down.gif";
name4a=new Image;name4a.src="button_05.gif";
name4b=new Image;name4b.src="button_05_down.gif";
name4c=new Image;name4c.src="button_05_down.gif";
}
function checkbrowser()
{
 if (browser != 'IE' || entrance == 'no')
   alert('Ezt az oldalt Internet Explorer 4+ böngésző és Cortona VRML kliensre optimalizáltam. Más böngészőkkel megtekintve a lapot menü rendszer nem működik.');
}
function change(x) 
{
  document.cortona.scene = x;
  document.cortona.src = x;
}
function rndImg(){
if (entrance == 'yes'){
 x=Math.floor(11*Math.random());
 if ( x >= 10 ){
	 str = './screen/screen10.gif';
 }
 else{
 str = './screen/screen0' + x +'.gif';
 }
 document.screen.src = str;
}
}
function rndWRL(){
if (entrance == 'yes'){
 x=Math.floor(11*Math.random());
 if ( x == 10 ){
	 str = './screen/screen10.wrl';
 }
 else{
 str = './screen/screen0' + x +'.wrl';
 }
 change(str);
 
}
}
function lighten(imgName) {
if (entrance == 'yes'){
imgOn = eval(imgName + 'b.src');
document[imgName].src = imgOn;
}
}
function darken(imgName) {
if (entrance == 'yes'){
imgOff = eval(imgName + 'a.src');
document[imgName].src = imgOff;
}
}
function darken2(imgName) {
if (entrance == 'yes'){
imgClick = eval(imgName + 'c.src');
document[imgName].src = imgClick;
}
}