// サムネイル画像プリロード
function preloadImg(imgName) {
 for (var i = 0; i < imgName.length; i++) {
  if (document.images) (new Image()).src = imgName[i];
 }
}
var viewimgs = new Array(
'img/line1_1_on.jpg',
'img/line1_2_on.jpg',
'img/line1_3_on.jpg',
'img/line1_4_on.jpg',
'img/line1_5_on.jpg',
'img/line2_1_on.jpg',
'img/line2_2_on.jpg',
'img/line2_3_on.jpg',
'img/line2_4_on.jpg',
'img/line2_5_on.jpg',
'img/line3_1_on.jpg');
preloadImg(viewimgs);


//メイン画像切替

if(document.images) {
 var imgs = new Array();
 imgs[11] = new Image();  imgs[11].src = "img/pht1_1.jpg";
 imgs[12] = new Image();  imgs[12].src = "img/pht1_2.jpg";
 imgs[13] = new Image();  imgs[13].src = "img/pht1_3.jpg";
 imgs[14] = new Image();  imgs[14].src = "img/pht1_4.jpg";
 imgs[15] = new Image();  imgs[15].src = "img/pht1_5.jpg";
 
 imgs[21] = new Image();  imgs[21].src = "img/pht2_1.jpg";
 imgs[22] = new Image();  imgs[22].src = "img/pht2_2.jpg";
 imgs[23] = new Image();  imgs[23].src = "img/pht2_3.jpg";
 imgs[24] = new Image();  imgs[24].src = "img/pht2_4.jpg";
 imgs[25] = new Image();  imgs[25].src = "img/pht2_5.jpg";
 
 imgs[31] = new Image();  imgs[31].src = "img/pht3_1.jpg";
}

function chgimg(id, imgname) {
 if(document.images) {
  if(imgs[imgname]) {
    document.images[id].src = imgs[imgname].src;
  }
  else {
    document.images[id].src = imgname;
  }
 }
}