ue4-Network相关-变量同步

变量同步

• 变量同步的原则是：一定要在服务端修改该变量，也就是rpc调用 Run On Server方法（ue4-Network相关-rpc调用）中修改该变量，才会根据变量属性是否为 Replicated 决定是否同步给 服务器和所有客户端

• 蓝图中同步：

• 选择变量属性 Replication 为 Replicated，有三个可选值

• None：默认值，服务端不会同步给所有客户端
• Replicated：在服务端修改，会同步给其他客户端
• RepNotify：选择这个的时候，会 Functions 中生产一个变量 Var 对应的方法 OnRep_Var，在服务器修改 Var 的时候会回调 服务器和所有客户端 中该Actor的这个 OnRep_Var 方法，

• 参考：https://docs-origin.unrealengine.com/latest/INT/Gameplay/HowTo/Networking/ReplicateVariable/Blueprints/index.html
• c++中同步：
• 1. 在变量中加入标记 Replicated

  UPROPERTY(Replicated, EditAnywhere, BlueprintReadWrite, Category = AMyNetCharacter)
          int32 Cash;           

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• 重写 AActor 的 GetLifetimeReplicatedProps 方法，加入需要同步的变量 Cash

• #include "Net/UnrealNetwork.h" //包含net相关头文件
  
  
  void AMyNetCharacter::GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& OutLifetimeProps) const
  {
      Super::GetLifetimeReplicatedProps(OutLifetimeProps);
      DOREPLIFETIME(AMyNetCharacter, Cash);
  }           

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• 在构造函数中修改成员 bReplicates 为 true

• AMyNetCharacter::AMyNetCharacter()
  {
      Cash = ;
      bReplicates = true;
  }           

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  • 变量标记的可选值，和蓝图对应，意思差不多
  • NotReplicated：服务端不会同步给所有客户端
  • Replicated：在服务端修改，会同步给其他客户端
  • ReplicatedUsing：选择这个的时候，需要指定一个 Var 改变时对应的 OnRep_Var（命名无特殊要求，不过还是按照蓝图生成的规则以 OnRep_ 前缀）,一定要加上 UFUNCTION 给反射系统，在服务端修改 Var 的时候会回调这个 OnRep_Var 方法。规则和 Replicated 差不多，示例如下：

  UFUNCTION(BlueprintCallable, Category = AMyNetCharacter)
      virtual void OnRep_Money();
  
  void AMyNetCharacter::OnRep_Money()
  {
      FString msg = FString::Printf(TEXT("--- OnRep_Money money:%d"), Money);
      GEngine->AddOnScreenDebugMessage(-, , FColor::Red, *msg);
  }
  
      // 指定回调函数为 OnRep_Money
      UPROPERTY(ReplicatedUsing = OnRep_Money, EditAnywhere, BlueprintReadWrite, Category = AMyNetCharacter)
          int32 Money;
  
      //重写的 GetLifetimeReplicatedProps 方法中加入需要同步的变量
      DOREPLIFETIME(AMyNetCharacter, Money);           

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• 参考：https://docs-origin.unrealengine.com/latest/INT/Gameplay/Networking/Actors/Properties/index.html

• 有条件的同步给不同链接中的actor的变量

  • 会在服务端同步 Replicated 变量给所有客户端前做二次检查，满足条件的客户端才会被同步
  • 实际的作用场景，例如：本机控制的actor的一些属性，本地修改（假修改），同时告诉服务端修改（真实修改，同时做校验），然后同步给除本机外的所有客户端上的该actor修改，因为本机已经自己修改了。

  1. 做法和上面差不多，只需要修改第二步， DOREPLIFETIME_CONDITION

  UPROPERTY(Replicated, EditAnywhere, BlueprintReadWrite, Category = AMyNetCharacter)
          int32 Item1;
  
  void AMyNetCharacter::GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& OutLifetimeProps) const
  {
      Super::GetLifetimeReplicatedProps(OutLifetimeProps);
  
      DOREPLIFETIME_CONDITION(AMyNetCharacter, Item1, COND_AutonomousOnly); //只给自己控制的actor同步Item1变量
  }           

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• 然后在rpc调用服务端方法修改Item1变量，就能看到只有自己控制的actor中Item1改变了，其他客户端的没有改变，是因为这个 COND_AutonomousOnly 标记。

  

• • CallServerChangeItem1 是个 Run On Server 类型的方法。不明白的看这里：ue4-Network相关-rpc调用
  • c++中的控制条件枚举

  /** Secondary condition to check before considering the replication of a lifetime property. */
  UENUM(BlueprintType)
  enum ELifetimeCondition
  {
      COND_None =                            UMETA(DisplayName = "None"),                            // This property has no condition, and will send anytime it changes
      COND_InitialOnly =                     UMETA(DisplayName = "Initial Only"),                    // This property will only attempt to send on the initial bunch
      COND_OwnerOnly =                       UMETA(DisplayName = "Owner Only"),                      // This property will only send to the actor's owner
      COND_SkipOwner =                       UMETA(DisplayName = "Skip Owner"),                      // This property send to every connection EXCEPT the owner
      COND_SimulatedOnly =                   UMETA(DisplayName = "Simulated Only"),                  // This property will only send to simulated actors
      COND_AutonomousOnly =                  UMETA(DisplayName = "Autonomous Only"),                 // This property will only send to autonomous actors
      COND_SimulatedOrPhysics =              UMETA(DisplayName = "Simulated Or Physics"),            // This property will send to simulated OR bRepPhysics actors
      COND_InitialOrOwner =                  UMETA(DisplayName = "Initial Or Owner"),                // This property will send on the initial packet, or to the actors owner
      COND_Custom =                          UMETA(DisplayName = "Custom"),                          // This property has no particular condition, but wants the ability to toggle on/off via SetCustomIsActiveOverride
      COND_ReplayOrOwner =                   UMETA(DisplayName = "Replay Or Owner"),                 // This property will only send to the replay connection, or to the actors owner
      COND_ReplayOnly =                     UMETA(DisplayName = "Replay Only"),                     // This property will only send to the replay connection
      COND_SimulatedOnlyNoReplay =          UMETA(DisplayName = "Simulated Only No Replay"),        // This property will send to actors only, but not to replay connections
      COND_SimulatedOrPhysicsNoReplay =     UMETA(DisplayName = "Simulated Or Physics No Replay"),  // This property will send to simulated Or bRepPhysics actors, but not to replay connections
      COND_Max =                            UMETA(Hidden)
  };           

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• 蓝图中则有个 Replication Condition 下拉选项：

  

• 参考：https://docs-origin.unrealengine.com/latest/INT/Gameplay/Networking/Actors/Properties/Conditions/index.html