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。

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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)

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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。

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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