// preload images
var menuimg_typ0 = new Image();
var menuimg_typ1 = new Image();
var menuimg_ucinek0 = new Image();
var menuimg_ucinek1 = new Image();
var menuimg_vyrobce0 = new Image();
var menuimg_vyrobce1 = new Image();

var switch_typ = false;
var switch_ucinek = true;
var switch_vyrobce = true;

menuimg_typ0.src = "./graphics/menu_typ0.gif";
menuimg_typ1.src = "./graphics/menu_typ1.gif";
menuimg_ucinek0.src = "./graphics/menu_ucinek0.gif";
menuimg_ucinek1.src = "./graphics/menu_ucinek1.gif";
menuimg_vyrobce0.src = "./graphics/menu_vyrobce0.gif";
menuimg_vyrobce1.src = "./graphics/menu_vyrobce1.gif";



function chgMenu(menuid){
  // prohodi menu
  document.getElementById('menu_typ').style.display = 'none';
  document.getElementById('menu_ucinek').style.display = 'none';
  document.getElementById('menu_vyrobce').style.display = 'none';
  
  document.getElementById(menuid).style.display = 'block';

  switch(menuid){
    case "menu_typ": {
      switch_typ = false;
      switch_ucinek = true;
      switch_vyrobce = true;
      document.getElementById('menu_typimg').src=menuimg_typ1.src;
      document.getElementById('menu_ucinekimg').src=menuimg_ucinek0.src;
      document.getElementById('menu_vyrobceimg').src=menuimg_vyrobce0.src;
      
    }break;
    case "menu_ucinek": {
      switch_typ = true;
      switch_ucinek = false;
      switch_vyrobce = true;
      document.getElementById('menu_typimg').src=menuimg_typ0.src;
      document.getElementById('menu_ucinekimg').src=menuimg_ucinek1.src;
      document.getElementById('menu_vyrobceimg').src=menuimg_vyrobce0.src;
    }break;
    case "menu_vyrobce": {
      switch_typ = true;
      switch_ucinek = true;
      switch_vyrobce = false;
      document.getElementById('menu_typimg').src=menuimg_typ0.src;
      document.getElementById('menu_ucinekimg').src=menuimg_ucinek0.src;
      document.getElementById('menu_vyrobceimg').src=menuimg_vyrobce1.src;
    }break;
  
  
  }
}