Tutorial 7 — Online multiplayer

JumPHP connects players through a relay server (WebSocket): the same online code on the desktop and in the browser. The Pong game is the complete example (src/Scene/PlayScene.php).

The lobby

$this->scenes()->switchTo(LobbyScene::class, [
    'next' => PlayScene::class,             // the game scene, once the players are gathered
    'nextParams' => ['mode' => 'online'],
    'back' => TitleScene::class,
    'players' => 2,
]);

The lobby creates a room (a 4-letter code to share), joins one, or finds an opponent. Then it opens the game scene with ['online' => true, 'net' => NetSession, 'host' => bool, 'peer' => int].

Messages

$net = $params['net'];
$net->removeAllListeners();
$net->on('message', fn (int $from, int $type, string $payload) => $this->receive($from, $type, $payload));
$net->on('peerLeave', fn (int $peer) => $this->scenes()->switchTo(TitleScene::class));

$net->send(self::MSG_STATE, pack('gg', $this->x, $this->y), reliable: false);   // frequent: may get lost
$net->sendJson(self::MSG_EVENT, ['goal' => 1]);                                   // rare: always arrives

The right setup

• The host decides: it simulates the match, keeps the score, and sends the state ~20 times per second;
• the others send their inputs ~30 times per second;
• the other players' objects are drawn with a small smoothed delay: SnapshotBuffer (push($this->engine->time(), $state) then sample($this->engine->time())).

Run the relay server on your machine with bin/jumphp relay up; the game sets its own with net_url in game.yaml (or ?net=wss://… in the page address).