[Sarteck]

It'd likely have to be passed to PHP by JavaScript, if you were to do it. And that would mean that the first page a user loads would NOT display the correct Style-By-Resolution, but subsequent ones would.

Let's see, you could do something like... Make a page that basically says "Please wait a moment while we detect your browser resolution." On that page, you could have JavaScript set the URL according to the screen size.

<script type="text/javascript" language="javascript">
function get_styleid_by_resolution()
{
  var x = screen.width;
  var y = screen.height;
  var resolution = x+'x'+y;
  var styleid_by_res = 0;
  switch(resoltuion)
  {
    case '1024x768':  styleid_by_res = 1; break;
    case '1280x800':  styleid_by_res = 2; break;
    case '1920x1080':  styleid_by_res = 3; break;
    case '320xwhatever':  styleid_by_res = 4; break;
    /* Etc. */
  }
  return styleid_by_res;
}
function set_styleid_in_url(sid)
{
  location.href = 'http://my.forum/respage.php?styleid='+sid+'&res_set=1';
}
</script>

The res_set is a variable your respage.php would have to set into the cookie, like so:

PHP Code:

vbsetcookie('res_set',1); 


Then you'd need a plugin (maybe somewhere in the Global stuff) to check to see if the res_set is set.

PHP Code:

$res_set = $vbulletin->input->clean_gpc('c', 'res_set', 'TYPE_BOOL');
if (!$res_set)
{
  /// Do some redirection to resolution setting page, I guess
  $vbulletin->url = 'res_page.php'.$vbulletin->session->vars['sessionurl'];
  print_standard_redirect('We\'re, like, gunna try to detect your resolution and shit.', false, true);
  die();
} 


Mind you, this isn't meant to be followed step-by-step; it's just a general idea of what you'd have to code for it. (Although someone else probably has a better idea.)