april_fools.module

<?php

function april_fools_compute_angle($h, $m) {
  $angle = ((intval($h) * 60 + intval($m)) / (24*60) * 360);
  // $angle = (sin(deg2rad($angle / 2)) * 360 + 90) % 360;
  return $angle;
}

function april_fools_node_view($node, $view_mode, $langcode) {
  $date = date("md");
  if ($date == "0401") {
    $hours = date("G");
    $mins = date("i");
    $angle = april_fools_compute_angle($hours, $mins);
    /* $h = array(); */
    /* for ($i = 0; $i <= 24; $i++) { */
    /*   $h[$i] = april_fools_compute_angle($i, 0); */
    /* } */
    /* kpr($h); */
    /* error_log("Angle: $angle"); */
    drupal_add_css(
      "body {" .
      " -webkit-transform: perspective(5000px) rotateY(" . intval($angle) . "deg);" .
      " -moz-transform: perspective(5000px) rotateY(" . intval($angle) . "deg);" .
      "}",
      array('type' => 'inline', 'preprocess' => FALSE));
  }
}