Note that imageFilledArc() and imageArc() both take ints as degree measurements. This is no problem if you're *only* using imageArc() and/or imageFilledArc(). However, if you're using calculated degrees and plan to superimpose other drawing elements (eg., you want to make vertical lines between the shadow 3D effect) you need to floor() your degrees before converting them to radians, otherwise you'll get precision errors.
A small example illustrating the 'feature'...
<?php
$img = imageCreate(400, 400);
$back = imageColorAllocate($img, 0, 0, 0);
$front = imageColorAllocate($img, 255, 255, 255);
$sd = 45.5;
$ed = 130.5;
imageFilledArc($img, 200, 200, 300, 300, $sd, $ed,
$front, IMG_ARC_PIE|IMG_ARC_NOFILL|IMG_ARC_EDGED);
imageArc($img, 200, 230, 300, 300, $sd, $ed, $front);
imageLine($img,
cos(deg2rad($sd))*150+200, sin(deg2rad($sd))*150+200,
cos(deg2rad($sd))*150+200, sin(deg2rad($sd))*150+230,
$front);
imageLine($img,
cos(deg2rad($ed))*150+200, sin(deg2rad($ed))*150+200,
cos(deg2rad($ed))*150+200, sin(deg2rad($ed))*150+230,
$front);
header('Content-type: image/png');
imagepng($img);
imagedestroy($img);
?>
And this is how it should be...
<?php
$img = imageCreate(400, 400);
$back = imageColorAllocate($img, 0, 0, 0);
$front = imageColorAllocate($img, 255, 255, 255);
$sd = floor(45.5);
$ed = floor(130.5);
imageFilledArc($img, 200, 200, 300, 300, $sd, $ed,
$front, IMG_ARC_PIE|IMG_ARC_NOFILL|IMG_ARC_EDGED);
imageArc($img, 200, 230, 300, 300, $sd, $ed, $front);
imageLine($img,
cos(deg2rad($sd))*150+200, sin(deg2rad($sd))*150+200,
cos(deg2rad($sd))*150+200, sin(deg2rad($sd))*150+230,
$front);
imageLine($img,
cos(deg2rad($ed))*150+200, sin(deg2rad($ed))*150+200,
cos(deg2rad($ed))*150+200, sin(deg2rad($ed))*150+230,
$front);
header('Content-type: image/png');
imagepng($img);
imagedestroy($img);
?>
