ue4-Network相关-组件及数据同步

• UActorComponent 及 Non-UActorComponent 同步
• Non-UActorComponent同步 可以理解为继承 UObject 的类，用来装数据的同时又需要暴露给蓝图调用，且带同步功能。

组件的同步和 Actor 的同步非常相似

Actor同步的传送门：ue4-Network相关-变量同步

• 新建一个组件类 UMyComp

  • MyComp.h

    
    #pragma once
    
    
    #include "MyComp.generated.h"
    
    UCLASS(Blueprintable, BlueprintType)
    class UMyComp : public UTextRenderComponent
    {
        GENERATED_BODY()
    public:
        UMyComp();
    
        UFUNCTION(BlueprintCallable, Category = AMyNetCharacter)
            virtual void OnRep_Length();
    
    public:
        UPROPERTY(ReplicatedUsing = OnRep_Length, EditAnywhere, BlueprintReadWrite, Category = UMyComp)
            int32 Length;
    };

  • MyComp.cpp

    
    #include "MyNet.h"
    
    
    #include "MyComp.h"
    
    
    #include "Net/UnrealNetwork.h"
    
    
    UMyComp::UMyComp() : Super()
    {
        UE_LOG(LogMyNet, Warning, TEXT("--- UMyComp::UMyComp"));
        Length = 789;
        bReplicates = true;
    }
    
    void UMyComp::GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& OutLifetimeProps) const
    {
        Super::GetLifetimeReplicatedProps(OutLifetimeProps);
        DOREPLIFETIME(UMyComp, Length);
    }
    
    void UMyComp::OnRep_Length()
    {
        SetText(FText::FromString(FString::Printf(TEXT("Length:%d"), Length)));
    }
    

• 组件的同步分为两大类：静态组件 同步 和 动态组件 同步

  1. 静态组件：直接在 c++中构造函数中 CreateDefaultSubobject 构造出来的，or 蓝图中直接 Add Comonent 上去的，在实例化 Actor 后就在 Actor 身上的，这种情况下，只要 Actor 是 Replicated 类型的，就自动会在其他客户端同步该 静态组件，无需指定该 静态组件 为 Replicated 类型。只有在该 静态组件 里面有需要同步的变量或者事件时，才需要指定为 Replicated 类型

     • 蓝图

       1. 这里新建了一个蓝图类 MyCompBp 继承 UMyComp，再起一个 RepNotify 类型的 Num 变量，在改变时修改展示内容。然后在 Actor 中 Add Componen 挂上去
          
          
          

       2. 测试蓝图中的变量是否能同步
          

       3. 结果：（在Client2中操作）
          

     • c++

       1. 在 Actor 的构造函数中创建，在 Actor 的蓝图就可以看见该组件

          AMyNetCharacter::AMyNetCharacter()
          {
              CusComp = CreateDefaultSubobject<UMyComp>(TEXT("CusComp"));
              CusComp->SetupAttachment(RootComponent);
              //CusComp->SetNetAddressable();
              CusComp->SetIsReplicated(true);
          }

          

       2. 测试c++中的变量是否能同步
          

          • 结果：(就不贴了)

  2. 动态组件：游戏运行时中动态实例化出来或删除的组件（必须在服务端上Spawn or Destroy）。必须指定为 Replicated 类型才能同步给所有客户端。

     • 蓝图

       1. 蓝图中动态实例化组件接口 Add Component，实例化出来一定要调用 SetIsReplicated 接口，同时 DyCusCompBp 变量也必须是 Replicated 类型
          

       2. 在测试一下变量同步
          

          • 结果：(就不贴了)

     • c++

       1. 在actor中写个接口给蓝图调用

          UPROPERTY(Replicated, EditAnywhere, BlueprintReadWrite, Category = AMyNetCharacter)
              UMyComp* DynamicCusComp22;
          
          UFUNCTION(BlueprintCallable, Category = AMyNetCharacter)
              virtual void SpawnMyComp();
          
          void AMyNetCharacter::GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& OutLifetimeProps) const
          {
              DOREPLIFETIME(AMyNetCharacter, DynamicCusComp22);
          }
          
          void AMyNetCharacter::SpawnMyComp()
          {
              if (DynamicCusComp22)
                  DynamicCusComp22->DestroyComponent();
          
              DynamicCusComp22 = NewObject<UMyComp>(this, UMyComp::StaticClass());
              DynamicCusComp22->RegisterComponent();
              FAttachmentTransformRules AttachmentRules(EAttachmentRule::KeepRelative, false);
              DynamicCusComp22->AttachToComponent(GetRootComponent(), AttachmentRules);
              DynamicCusComp22->SetRelativeLocation(FVector(0.f, 100.f, 50.f));
              //DynamicCusComp22->SetNetAddressable(); //绝逼不能调这个，否则所有客户端断线
              DynamicCusComp22->SetIsReplicated(true);
          }

          • 官网说要手动调用这个标记 Manually marked (via UActorComponent::SetNetAddressable)，实测不行，有待研究源码。会报错：Stably named sub-object not found. Component
            

       2. 在测试一下变量同步
          

          • 结果：(就不贴了)

自定义类（继承UObject）的同步，可用作数据同步

1. 新建个继承 UObject 的数据类 UMyItem

   • MyItem.h

     
     #pragma once
     
     
     #include "MyItem.generated.h"
     
     
     UCLASS(Blueprintable, BlueprintType)
     class UMyItem : public UObject
     {
         GENERATED_BODY()
     public:
         UMyItem();
         virtual ~UMyItem();
     public:
         UFUNCTION()
             virtual void OnRep_Count();
     
         virtual bool IsSupportedForNetworking() const override
         {
             return true;
         }
     
     public:
         UPROPERTY(ReplicatedUsing = OnRep_Count, EditAnywhere, BlueprintReadWrite, Category = UMyItem)
             int32       Count;
     };

   • MyItem.cpp

     
     #include "MyNet.h"
     
     
     #include "MyItem.h"
     
     
     
     #include "Net/UnrealNetwork.h"
     
     
     UMyItem::UMyItem() : Super()
     {
         UE_LOG(LogMyNet, Warning, TEXT("--- UMyItem::UMyItem"));
         Count = 32;
     }
     
     UMyItem::~UMyItem()
     {
         UE_LOG(LogMyNet, Warning, TEXT("--- UMyItem::~UMyItem"),);
     }
     
     void UMyItem::OnRep_Count()
     {
         FString msg = FString::Printf(TEXT("--- OnRep_Count Count:%d"), Count);
         GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Green, *msg);
     }
     
     void UMyItem::GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& OutLifetimeProps) const
     {
         Super::GetLifetimeReplicatedProps(OutLifetimeProps);
         DOREPLIFETIME(UMyItem, Count);
     }

     • 规则也是和 Actor 同步差不多，没有了 bReplicates = true; 成员，需要同步的变量加上 Replicated 标记，实现 GetLifetimeReplicatedProps 方法。需要实现 IsSupportedForNetworking

2. 在 Replicated Actor 中重写几个函数

       virtual bool ReplicateSubobjects(class UActorChannel *Channel, class FOutBunch *Bunch, FReplicationFlags *RepFlags) override;
       //virtual void OnSubobjectCreatedFromReplication(UObject *NewSubobject); 不知道为啥重写这两个函数会造成不能同步，逻辑上看起来没问题，有待探究
       //virtual void OnSubobjectDestroyFromReplication(UObject *Subobject);
   
       bool AMyNetCharacter::ReplicateSubobjects(class UActorChannel *Channel, class FOutBunch *Bunch, FReplicationFlags *RepFlags)
   {
       bool WroteSomething = Super::ReplicateSubobjects(Channel, Bunch, RepFlags);
       if (CusObj != nullptr)
       {
           WroteSomething |= Channel->ReplicateSubobject(CusObj, *Bunch, *RepFlags);
       }
       return WroteSomething;
   }
   /*
   void AMyNetCharacter::OnSubobjectCreatedFromReplication(UObject *NewSubobject)
   {
       Super::OnSubobjectCreatedFromReplication(NewSubobject);
       FString msg = FString::Printf(TEXT("--- OnSubobjectCreatedFromReplication ClassName:%s"), *NewSubobject->GetClass()->GetName());
       GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, *msg);
   }
   
   void AMyNetCharacter::OnSubobjectDestroyFromReplication(UObject *Subobject)
   {
       FString msg = FString::Printf(TEXT("--- OnSubobjectDestroyFromReplication ClassName:%s"), *Subobject->GetClass()->GetName());
       GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, *msg);
       Super::OnSubobjectDestroyFromReplication(Subobject);
   }
   */

   • 从源码来看，network 会每帧调用到 actor 的 ReplicateSubobjects
     

3. 在服务端生产一个对象，然后会同步到所有客户端
   

       UFUNCTION(BlueprintCallable, Category = AMyNetCharacter)
           virtual void SpawnMyItem();
   
   void AMyNetCharacter::SpawnMyItem()
   {
       if (!HasAuthority()) //确保是服务端去new组件
           return;
   
       if (CusObj)
           CusObj->ConditionalBeginDestroy();
   
       CusObj = NewObject<UMyItem>(this, UMyItem::StaticClass());
   }

4. 测试修改一下里面的数据是否能同步到其他客户端
   

5. 结果：（在Client2中操作）
   

   • 在 Replicated Actor 中示例化 UMyItem 时会在 所有客户端同步回调

     virtual void OnSubobjectCreatedFromReplication(UObject *NewSubobject);

   • 在销毁 Replicated Actor 的时候会会在所有客户端 销毁 UMyItem

     virtual void OnSubobjectDestroyFromReplication(UObject *Subobject);

   • 在源码中没有找到 动态销毁UMyItem 的方法，它只有在 Actor 销毁的时候跟着被销毁。所以还不能完全控制（应该是我还找到）。想要完全控制的话可以用 UActorComponent。

参考资料

• https://docs-origin.unrealengine.com/latest/INT/Gameplay/Networking/Actors/Components/index.html#optimizations
• https://wiki.unrealengine.com/Replication#Advanced:_Generic_replication_of_Actor_Subobjects
• https://answers.unrealengine.com/questions/361181/bug-getlifetimereplicatedprops-calls-only-once-on.html?sort=oldest