If players is in radius

I tried to check if there is a special block in a radius of 7 blocks from a player. I placed a sign under the block. But it only works sometimes. What is wrong?

PHP:

foreach ($player->getLevel()->getTiles() as $b) {
if($b instanceof Sign) {
$distance = sqrt(($player->x - $b->x)*($player->x - $b->x) + ($player->y - $b->y)*($player->y - $b->y) + ($player->z -
$b->z)*($player->z - $b->z));
if ($distance < 7) {

}

 

You can try

PHP:

foreach ($player->getLevel()->getTiles() as $b) {
    if($b instanceof Sign) {
        if($b->distanceSquared($player) < 49){
        //do smth
        }
    }
}

 

you can look here: https://github.com/pmmp/PocketMine-MP/blob/master/src/pocketmine/math/Vector3.php#L179