Here's the function to draw rotated ellipses again. This time I've optimised it a bit, fixed the no-fill bug, and used a 'squishratio' rather than a 'radiusmodifier', to make the curves perfect, so ignore my previous version.

<?php
function rotatedellipse($im, $cx, $cy, $width, $height, $rotateangle, $colour, $filled=true) {
   $step=2;
   $cosangle=cos(deg2rad($rotateangle));
   $sinangle=sin(deg2rad($rotateangle));

   $squishratio = $height/$width;
   $nopreviouspoint = true;
   for ($angle=0; $angle<=(180+$step); $angle+=$step) {
       
      $ox = ($width * cos(deg2rad($angle)));
      $oy = ($width * sin(deg2rad($angle))) * $squishratio;

      $x =  + (($ox * $cosangle) - ($oy * $sinangle));
      $y = $centrey + (($ox * $sinangle) + ($oy * $cosangle));
  
      if ($nopreviouspoint) {
        $px=$x;
        $py=$y;
        $nopreviouspoint=false;
      }

      if ($filled) {
         triangle($im, $cx, $cy, $cx+$px, $cy+$py, $cx+$x, $cy+$y, $colour);
         triangle($im, $cx, $cy, $cx-$px, $cx-$py, $cx-$x, $cy-$y, $colour);
      } else {
         imageline($im, $cx+$px, $cy+$py, $cx+$x, $cy+$y, $colour); 
         imageline($im, $cx-$px, $cx-$py, $cx-$x, $cy-$y, $colour); 
      }
      $px=$x;
      $py=$y;
   } 
}

function triangle($im, $x1,$y1, $x2,$y2, $x3,$y3, $colour) {
   $coords = array($x1,$y1, $x2,$y2, $x3,$y3);
   imagefilledpolygon($im, $coords, 3, $colour); 
}
?>