ModalFormSample.php

$data = array(
    "type" => "modal",
    "title" => "タイトル",
    "content" => "選んでください",
    "button1" => "はい",
    "button2" => "いいえ",
);
$pk = new ModalFormRequestPacket();
$pk->formId = /*自由なint*/;
$pk->formData = json_encode($data);
$player->dataPacket($pk);