var default_opacity = 0.2;
var animate_time = 1000;
var num_images = 152;

function fix_resolutions() {
  var img = $('#imgloader').get(0);
  var img_ratio = img.naturalWidth / img.naturalHeight;
  var wnd_ratio = window.innerWidth / window.innerHeight;
  $("#back").css("background-size", img_ratio > wnd_ratio ? "auto 100%" : "100% auto");
}

function set_random_img() {
  var img = $('#imgloader').attr('src');
  var back = $('#back');
  
  back.animate({opacity: 0}, animate_time, 'swing', function() {
    back.css("background-image", "url('" + img + "')");
    fix_resolutions();
    back.animate({opacity: default_opacity}, animate_time);
  });
}

function select_random_img() {
  $('#imgloader').attr('src', "static/imgs/" + (Math.floor(Math.random() * num_images) + 1) + ".jpg");
}

$( document ).ready(function() {
  $('#imgloader').attr('src', '').load(set_random_img);
  select_random_img();
  
  $(window).resize(fix_resolutions);
  window.setInterval(select_random_img, 10000);
});

var default_opacity = 0.2;
var animate_time = 0;
var default_animate_time = 1000;
var num_images = 152;

function fix_resolutions() {
  var img = $('#imgloader').get(0);
  var img_ratio = img.naturalWidth / img.naturalHeight;
  var wnd_ratio = window.innerWidth / window.innerHeight;
  $("#back").css("background-size", img_ratio > wnd_ratio ? "auto 100%" : "100% auto");
}

function set_random_img() {
  var img = $('#imgloader').attr('src');
  var back = $('#back');
  
  back.animate({opacity: 0}, animate_time, 'swing', function() {
    if(animate_time == 0) { animate_time = default_animate_time; }

    back.css("background-image", "url('" + img + "')");
    fix_resolutions();
    back.animate({opacity: default_opacity}, animate_time);
  });
}

function select_random_img() {
  $('#imgloader').attr('src', "static/imgs/" + (Math.floor(Math.random() * num_images) + 1) + ".jpg");
}

$( document ).ready(function() {
  $('#imgloader').attr('src', '').load(set_random_img);
  select_random_img();
  
  $(window).resize(fix_resolutions);
  window.setInterval(select_random_img, 10000);
});

Load background faster first time
Load background faster first time
