$x = 200;

$y = 200;

$gd = imagecreatetruecolor($x, $y);

$corners[0] = array('x' => 100, 'y' => 10);

$corners[1] = array('x' => 0, 'y' => 190);

$corners[2] = array('x' => 200, 'y' => 190);

$red = imagecolorallocate($gd, 255, 255, 255);

for ($i = 0; $i < 100000; $i++) {

imagesetpixel($gd, round($x),round($y), $red);

$a = rand(0, 2);

$x = ($x + $corners[$a]['x']) / 2;

$y = ($y + $corners[$a]['y']) / 2;

header('Content-Type: image/png');

imagepng($gd);

After running the program you will get the following output

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