dot.php

<?php

/**
 * @param number $x           the X coordinate of the center of the circle
 * @param number $y           the Y coordinate to place particles at
 * @param number $z           the Z coordinate of the center of the circle
 * @param number $radius      the distance for each dot from the center
 * @param number $step        the angle per step, in degrees
 * @param callable $callback  the function to call for each dot, with parameters $x, $y, $z representing the coordinates of the dot
 */
function dot($x, $y, $z, $radius, $step, callable $callback){
	$step *= M_PI / 180; // equivalent to deg2rad, but faster
	for($r = 0; $r < M_PI_2; $r += $step){
		$tx = -sin($r) * $radius + $x;
		$tz = cos($r) * $radius + $z;
		$callback($tx, $y, $tz);
	}
}