SceneManager.cpp

class SceneManager {
 public:
  SceneManager() {
    null_vtable_ = GetVtable(&null_object_);
  }

  void Add(SceneObject* obj) {
    SceneObject_VTable* vtable = GetVtable(obj);

    if (vtable->update != null_vtable_->update) {
      update_fns_.insert({ vtable->update, obj });
    }

    if (vtable->late_update != null_vtable_->late_update) {
      late_update_fns_.insert({ vtable->late_update, obj });
    }

    if (vtable->physics_update != null_vtable_->physics_update) {
      physics_update_fns_.insert({ vtable->physics_update, obj });
    }

    if (vtable->draw_immediate != null_vtable_->draw_immediate) {
      draw_immediate_fns_.insert({ vtable->draw_immediate, obj });
    }
  }

  void UpdateAll() {
    for (auto& fn : update_fns_) {
      fn.first(fn.second);
    }
  }

  void LateUpdateAll() {
    for (auto& fn : late_update_fns_) {
      fn.first(fn.second);
    }
  }

  void PhysicsUpdateAll() {
    for (auto& fn : physics_update_fns_) {
      fn.first(fn.second);
    }
  }

  void DrawImmediateAll() {
    for (auto& fn : draw_immediate_fns_) {
      fn.first(fn.second);
    }
  }

 private:
  SceneObject null_object_;
  SceneObject_VTable* null_vtable_;

  std::set<SceneObject*> objects_;

  std::set<std::pair<UpdateFn*, void*>, CompareUpdateFns> update_fns_;
  std::set<std::pair<UpdateFn*, void*>, CompareUpdateFns> late_update_fns_;
  std::set<std::pair<UpdateFn*, void*>, CompareUpdateFns> physics_update_fns_;
  std::set<std::pair<UpdateFn*, void*>, CompareUpdateFns> draw_immediate_fns_;
};