Delta3D GameActor 和 GameActorProxy 中关键函数解析

本文基于Delta3d 2.8 版本

1, OnEnteredWorld()函数，在Actors和proxy均有此函数。在actor在第一次加入到GameManager中时调用。In Proxy's OnEnteredWorld,This is a good place to register Invokables with MessageTypes.

在GameManager 的函数中AddActor(GameActorProxy& gameActorProxy, bool isRemote, bool publish)调用Proxy 的 InvokeEnteredWorld()函数

此函数在GameActorProxy::InvokeEnteredWorld()中调用，如下

void GameActorProxy::InvokeEnteredWorld()
{
   /**
   * We will perform a check to make sure this actor actually is a GameActor
   */

   GameActor* ga = dynamic_cast<GameActor*>(GetDrawable());
   if (ga == NULL)
   {
      // throw exception
      throw dtGame::GeneralGameManagerException(
         "ERROR: Actor has the type of a GameActor, but casting it to a GameActorProxy failed.", __FILE__, __LINE__);
   }

   ga->OnEnteredWorld();
   CallOnEnteredWorldForActorComponents();

   OnEnteredWorld();
}

然后在GameManager中的AddActor函数中调用gameActorProxy.InvokeEnteredWorld();

2. CreateDrawable() 函数（2.75版本这个函数叫 叫crateActor），这个是ProxyActor  必须要实现的，用来创建proxy对应的actor，然后调用SetDrawable();

如下面代码片段

* @code
       * void MyProxy::CreateDrawable()
       * {
       *    MyDrawable* draw = new MyDrawable();
       *    assert(draw);
       *    SetDrawable(*Drawable);
       * }
       * @endcode

这个函数是在BaseActorObject::Init（）函数中调用的。

void BaseActorObject::Init(const dtCore::ActorType& actorType)
   {
      SetActorType(actorType);
      CreateDrawable();
      // These are called to make it validate that they aren't Null
      // before proceeding.
      GetActorType();
      GetDrawable();
      BuildPropertyMap();
   }

3. void GameActorProxy::BuildInvokables() 函数。

创建可调用体，在创建自定义“可调用体时”，要使用继承的可调用体，确保也要调用继承类的BuildInvokables(); 注意：不要忘记注册你的“可调用体”感兴趣的消息类型，一般在OnEnteredWorld（）函数中调用RegisterForMessages（）进行注册。否则，你的“可调用体”函数，如ProcessMessage，将得不到执行）；

此函数的调用位置如下：

void GameActorProxy::Init(const dtCore::ActorType& actorType)
{
   BaseClass::Init(actorType);
   BuildInvokables();
   BuildActorComponents();

   // The actor components are stored on the game actor, unlike the other stuff
   GameActor &ga = GetGameActor();
   ga.BuildActorComponents();
}

而init的调用如下：

 dtCore::RefPtr<BaseActorObject> ActorPluginRegistry::CreateActor(const ActorType& type)
   {
      dtCore::RefPtr<BaseActorObject> proxy = mActorFactory->CreateObject(dtCore::RefPtr<const ActorType>(&type));
      proxy->Init(type);
      proxy->InitDefaults();
      return proxy;
   }

4. void GameActorProxy::BuildPropertyMap() 函数。

创建此proxy所关联的属性信息，注册到子类PropertyContianer中。在 BaseActorObject::Init(const dtCore::ActorType& actorType)中创建，见上面分析。

5. virtual void BuildActorComponents(); 函数

actor 和proxy均有此方法。同样在 void GameActorProxy::Init(const dtCore::ActorType& actorType)中创建的，见上分析。

   void GameActor::AddComponent(ActorComponent& component)
   {
      ActorComponentBase::AddComponent(component);

      // add actor component properties to the game actor itself
      // note - the only reason we do this is to make other parts of the system work (like STAGE).
      // In the future, STAGE (et al) should use the actor components directly and we won't add them to the game actor
      // Remove the props from the game actor - This is temporary. See the note in AddComponent()
      GetGameActorProxy().AddActorComponentProperties(component);

      // initialize component
      component.OnAddedToActor(*this);
      OnActorComponentAdded(component);

      // if base class is a game actor and the game actor is already instantiated in game:
      if (GetGameActorProxy().IsInGM())
      {
         component.SetIsInGM(true);
         component.OnEnteredWorld();
      }
   }