ue4-Network相关-变量同步

蓝图 or c++ 的 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;

  2. 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);
     }

  3. 在构造函数中修改成员 bReplicates 为 true

     AMyNetCharacter::AMyNetCharacter()
     {
         Cash = 456;
         bReplicates = true;
     }

     • 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(-1, 5.f, 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);

     • 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
   }

2. 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 = 0                           UMETA(DisplayName = "None"),                            // This property has no condition, and will send anytime it changes
         COND_InitialOnly = 1                    UMETA(DisplayName = "Initial Only"),                    // This property will only attempt to send on the initial bunch
         COND_OwnerOnly = 2                      UMETA(DisplayName = "Owner Only"),                      // This property will only send to the actor's owner
         COND_SkipOwner = 3                      UMETA(DisplayName = "Skip Owner"),                      // This property send to every connection EXCEPT the owner
         COND_SimulatedOnly = 4                  UMETA(DisplayName = "Simulated Only"),                  // This property will only send to simulated actors
         COND_AutonomousOnly = 5                 UMETA(DisplayName = "Autonomous Only"),                 // This property will only send to autonomous actors
         COND_SimulatedOrPhysics = 6             UMETA(DisplayName = "Simulated Or Physics"),            // This property will send to simulated OR bRepPhysics actors
         COND_InitialOrOwner = 7                 UMETA(DisplayName = "Initial Or Owner"),                // This property will send on the initial packet, or to the actors owner
         COND_Custom = 8                         UMETA(DisplayName = "Custom"),                          // This property has no particular condition, but wants the ability to toggle on/off via SetCustomIsActiveOverride
         COND_ReplayOrOwner = 9                  UMETA(DisplayName = "Replay Or Owner"),                 // This property will only send to the replay connection, or to the actors owner
         COND_ReplayOnly = 10                    UMETA(DisplayName = "Replay Only"),                     // This property will only send to the replay connection
         COND_SimulatedOnlyNoReplay = 11         UMETA(DisplayName = "Simulated Only No Replay"),        // This property will send to actors only, but not to replay connections
         COND_SimulatedOrPhysicsNoReplay = 12    UMETA(DisplayName = "Simulated Or Physics No Replay"),  // This property will send to simulated Or bRepPhysics actors, but not to replay connections
         COND_Max = 13                           UMETA(Hidden)
     };

   • 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