pocketmine\Player::canSee PHP Method

    public function canSee(Player $player) : bool
    {
        return !isset($this->hiddenPlayers[$player->getRawUniqueId()]);
    }

 public function spawnTo(Player $player)
 {
     if ($player instanceof DesktopPlayer) {
         if ($this !== $player and $this->spawned === true and $player->getLevel() === $this->getLevel() and $player->canSee($this)) {
             $this->hasSpawned[$player->getID()] = $player;
             $pk = new SpawnPlayerPacket();
             if ($player->getRemoveFormat()) {
                 $pk->name = TextFormat::clean($this->nameTag);
             } else {
                 $pk->name = $this->nameTag;
             }
             $pk->eid = $this->getID();
             $pk->uuid = $this->bigBrother_formatedUUID;
             $pk->x = $this->x;
             $pk->z = $this->y;
             $pk->y = $this->z;
             $pk->yaw = $this->yaw;
             $pk->pitch = $this->pitch;
             $pk->item = $this->inventory->getItemInHand()->getID();
             $pk->metadata = $this->getData();
             $pk->data = $this->bigBrother_properties;
             $player->putRawPacket($pk);
             $pk = new EntityTeleportPacket();
             $pk->eid = $this->getID();
             $pk->x = $this->x;
             $pk->z = $this->y;
             $pk->y = $this->z;
             $pk->yaw = $this->yaw;
             $pk->pitch = $this->pitch;
             $player->putRawPacket($pk);
             $pk = new SetEntityMotionPacket();
             $pk->eid = $this->getID();
             $pk->speedX = $this->motionX;
             $pk->speedY = $this->motionY;
             $pk->speedZ = $this->motionZ;
             $player->dataPacket($pk);
             $this->inventory->sendHeldItem($player);
             $this->inventory->sendArmorContents($player);
         }
     } else {
         parent::spawnTo($player);
     }
 }