Newton's Cradle

const renderLayers = {
  foreground: 1 << 0,
};

const gravity = new Vector2(0, -600);

export const createNewtonsCradleGame = async (): Promise<Game> => {
  const { game, world, renderContext, time } = createGame('demo-game');

  createCamera(world, {
    isStatic: true,
    cullingMask: renderLayers.foreground,
    verticalWorldUnits: DEMO_VERTICAL_WORLD_UNITS,
  });

  const physicsWorld = new PhysicsWorld({ gravity });

  await createCradle(
    world,
    renderContext,
    renderLayers.foreground,
    new Vector2(0, DEMO_VERTICAL_WORLD_UNITS * 0.3),
  );

  // `createRevoluteJointEcsSystem` must run before
  // `createPhysicsSyncEcsSystem`, which is what steps `physicsWorld`:
  // newly-added joints need to be registered before that step happens (see
  // the Revolute Joints guide's registration-order caution).
  // `createArmEcsSystem` only needs to run before `createRenderEcsSystem`,
  // so its updated arms are reflected in this tick's render.
  world.addSystem(createRevoluteJointEcsSystem(physicsWorld));
  world.addSystem(createArmEcsSystem());
  world.addSystem(createCameraEcsSystem(time));
  world.addSystem(createRenderEcsSystem(renderContext));
  world.addSystem(createPhysicsSyncEcsSystem(physicsWorld, time));

  return game;
};