gistfile1.php

<?php
$radius = 249;
$im = imagecreatetruecolor(500, 500);
imagefill($im, 0,0, imagecolorallocatealpha($im, 0,0,0,127));
imagealphablending($im, false	);
imagesavealpha($im, true);
$color_obj = 0xff0000;
$object_count = 20;
$object_radius = 10;

imagefilledellipse($im, 250,250, $radius, $radius, 0xFFFFFF);
$step_offset = deg2rad(360 / $object_count);
echo "step offset: $step_offset\n";

for ($i = 0; $i < $object_count; $i++) {
	$x = 250 + $radius/2 * cos($step_offset * $i);
	$y = 250 + $radius/2 * sin($step_offset * $i);
	echo "$x $y\n";
	imagefilledellipse($im, $x, $y, $object_radius, $object_radius, $object_color);
}

imagepng($im, 'circle.png');