教程 3 — 平台跳跃游戏：关卡、碰撞、摄像机

用文本行写成的关卡

起步时，关卡可以直接写在代码里：每个字符代表一块 16 × 16 像素的图块。

private const LEVEL = [
    '..........................C.C.C.........',
    '.........................=======........',
    '...P....................................',
    '#########............C......######......',
    '#########..........#####...########.....',
    '########################################',
];

$this->map = ArrayLoader::fromRows(self::LEVEL,
    legend: ['#' => 1, '=' => 2, '/' => 3, '\\' => 4],     // 图块
    objects: ['P' => 'start', 'C' => 'coin'],                // 放置在关卡中的物体
    tileWidth: 16, tileset: 'generated:tiles');
$tileset = $this->map->tilesets[0];
$tileset->masks[1] = CollisionMask::oneWay();                // '='：可以从下方跳穿过去
$tileset->masks[2] = CollisionMask::slope(16, 16, 1, 16);    // '/'：一个斜坡

当游戏变大后，请用 Tiled 来绘制关卡： TiledJsonLoader::load($this->engine->config->path('assets/maps/niveau1.tmj'))。

碰撞

在场景的构造函数中注入各项服务（它们会被自动提供）：

public function __construct(
    private TileMapRenderer $tiles,
    private CollisionSystem $collisions,
    private EntityManager $entities,
) {
}

每一帧，先设置速度，再通过碰撞系统移动：它会逐像素前进，在墙前停下，落在地面上，爬上斜坡，并填充 $player->onGround。

$this->player->control($move, $jump, $held, $dt);
$this->player->update($dt);
$this->collisions->move($this->player, $this->map, $dt);

掉出关卡：$this->collisions->on('fell', fn () => $this->respawn());（写在 enter() 中，位于 $this->collisions->removeAllListeners() 之后）。

金币

关卡中的物体会变成实体：

$this->entities->clear();
$this->entities->register('coin', Coin::class);
$this->entities->spawnFromMap($this->map);

// 在 update() 中：
$this->entities->update($dt, $this->camera);
foreach ($this->entities->overlapping($this->player->getBoundingBox()) as $entity) {
    if ($entity instanceof Coin) {
        $entity->kill();                    // 自动移除
        $this->coins++;
        $this->sound()->playSfx('coin');
    }
}

摄像机

$this->camera = new Camera($this->width(), $this->height());
$this->camera->setBounds(0, 0, $this->map->pixelWidth(), $this->map->pixelHeight());
$this->camera->follow($this->player, 0.15, 0.3);    // 屏幕中央有一块“死区”

// update()：$this->camera->update($dt);
// render()：所有内容都按摄像机的偏移来绘制
$cx = $this->camera->getX();
$cy = $this->camera->getY();
$this->tiles->renderBackground($r, $this->map, $cx, $cy, $this->time);
$this->entities->render($r, $this->camera);
$this->player->render($r, $cx, $cy);
$this->tiles->renderForeground($r, $this->map, $cx, $cy, $this->time);

$this->camera->shake(4, 0.3) 可以让屏幕抖动。完整的游戏就是 JumPHP 的骨架项目 （src/Scene/PlayScene.php）：bin/jumphp new mon-jeu 会把它交给你，可以直接修改。