message: fix ground plane's bounding box
diff: @@ -312,8 +312,7 @@ static void createGroundPlane(Engine* engine, Scene* scene, App& app) {
  Entity groundPlane = em.create();
  RenderableManager::Builder(1)
  .boundingBox({
  - { -planeExtent.x, 0, -planeExtent.z },
  - { planeExtent.x, 1e-4f, planeExtent.z }
  + {}, { planeExtent.x, 1e-4f, planeExtent.z }
  })
  .material(0, shadowMaterial->getDefaultInstance())
  .geometry(0, RenderableManager::PrimitiveType::TRIANGLES,
  