筆者最近正在從頭開始搭建一個(gè)多人射擊游戲拉盾，用于熟悉UE4 DS的方方面面桨菜，以及設(shè)計(jì)/性能優(yōu)化等方面的課題，做些零碎的筆記

3.關(guān)于網(wǎng)絡(luò)同步中捉偏，Character的Rotation同步倒得。

在搭建游戲過程中，筆者發(fā)現(xiàn)直接設(shè)置Character的Rotation夭禽，并不能同步到服務(wù)器及其他客戶端霞掺，所以趴一趴UE4對(duì)位置同步中Rotation的處理。
這里給各位的童鞋推薦大佬博客 https://blog.csdn.net/u012999985/article/details/78669947讹躯，對(duì)移動(dòng)同步方向?qū)懙暮茉敿?xì)菩彬，所以我這里只對(duì) Rotation 的問題進(jìn)說明缠劝。
首先找到服務(wù)器同步的移動(dòng)數(shù)據(jù)ReplicatedMovement，ReplicatedUsing類型的同步變量：

image.png

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首先找到客戶端發(fā)給服務(wù)器的同步請(qǐng)求servemove：

void UCharacterMovementComponent::ServerMove(float TimeStamp, FVector_NetQuantize10 InAccel, 
  FVector_NetQuantize100 ClientLoc, uint8 CompressedMoveFlags, uint8 ClientRoll, uint32 View, 
  UPrimitiveComponent* ClientMovementBase, FName ClientBaseBoneName, uint8 ClientMovementMode)
{
    if (MovementBaseUtility::IsDynamicBase(ClientMovementBase))
    {
        CharacterOwner->ServerMove(TimeStamp, InAccel, ClientLoc, CompressedMoveFlags, ClientRoll, View, ClientMovementBase, ClientBaseBoneName, ClientMovementMode);
    }
    else
    {
        CharacterOwner->ServerMoveNoBase(TimeStamp, InAccel, ClientLoc, CompressedMoveFlags, ClientRoll, View, ClientMovementMode);
    }
}

發(fā)現(xiàn) Rotation 相關(guān)數(shù)據(jù)來自參數(shù) uint32 View免都，向上追溯參數(shù)來源锉罐，可以看出其實(shí)客戶端發(fā)給服務(wù)器的Rotation只是ControlRotation。

void UCharacterMovementComponent::CallServerMove
    (
    const class FSavedMove_Character* NewMove,
    const class FSavedMove_Character* OldMove
    )
{
    check(NewMove != nullptr);

    // Compress rotation down to 5 bytes
    const uint32 ClientYawPitchINT = PackYawAndPitchTo32(NewMove->SavedControlRotation.Yaw, NewMove->SavedControlRotation.Pitch);
    const uint8 ClientRollBYTE = FRotator::CompressAxisToByte(NewMove->SavedControlRotation.Roll);
    ...

在服務(wù)器調(diào)用RPC處理客戶端移動(dòng)請(qǐng)求時(shí)調(diào)用UpdateRotation绕娘，在UpdateRotation中直接設(shè)置了Actor的Rotation為ControlRotation（當(dāng)然會(huì)考慮bUseControllerRotationPitch/bUseControllerRotationYaw/bUseControllerRotationRoll）的設(shè)置脓规，所以說了一大堆，就是DS同步以ControlRotation為基礎(chǔ)险领。

void UCharacterMovementComponent::ServerMove_Implementation(
    float TimeStamp,
    FVector_NetQuantize10 InAccel,
    FVector_NetQuantize100 ClientLoc,
    uint8 MoveFlags,
    uint8 ClientRoll,
    uint32 View,
    UPrimitiveComponent* ClientMovementBase,
    FName ClientBaseBoneName,
    uint8 ClientMovementMode)
{
  ...
  // Perform actual movement
    if ((MyWorld->GetWorldSettings()->Pauser == NULL) && (DeltaTime > 0.f))
    {
        if (PC)
        {
            PC->UpdateRotation(DeltaTime);
        }

        MoveAutonomous(TimeStamp, DeltaTime, MoveFlags, Accel);
    }
  ...
}

void APlayerController::UpdateRotation( float DeltaTime )
{
    // Calculate Delta to be applied on ViewRotation
    FRotator DeltaRot(RotationInput);

    FRotator ViewRotation = GetControlRotation();

    if (PlayerCameraManager)
    {
        PlayerCameraManager->ProcessViewRotation(DeltaTime, ViewRotation, DeltaRot);
    }

    AActor* ViewTarget = GetViewTarget();
    if (!PlayerCameraManager || !ViewTarget || !ViewTarget->HasActiveCameraComponent() || ViewTarget->HasActivePawnControlCameraComponent())
    {
        if (IsLocalPlayerController() && GEngine->XRSystem.IsValid() && GEngine->XRSystem->IsHeadTrackingAllowed())
        {
            auto XRCamera = GEngine->XRSystem->GetXRCamera();
            if (XRCamera.IsValid())
            {
                XRCamera->ApplyHMDRotation(this, ViewRotation);
            }
        }
    }

    SetControlRotation(ViewRotation);

    APawn* const P = GetPawnOrSpectator();
    if (P)
    {
        P->FaceRotation(ViewRotation, DeltaTime);
    }
}

void APawn::FaceRotation(FRotator NewControlRotation, float DeltaTime)
{
    // Only if we actually are going to use any component of rotation.
    if (bUseControllerRotationPitch || bUseControllerRotationYaw || bUseControllerRotationRoll)
    {
        const FRotator CurrentRotation = GetActorRotation();

        if (!bUseControllerRotationPitch)
        {
            NewControlRotation.Pitch = CurrentRotation.Pitch;
        }

        if (!bUseControllerRotationYaw)
        {
            NewControlRotation.Yaw = CurrentRotation.Yaw;
        }

        if (!bUseControllerRotationRoll)
        {
            NewControlRotation.Roll = CurrentRotation.Roll;
        }

#if ENABLE_NAN_DIAGNOSTIC
        if (NewControlRotation.ContainsNaN())
        {
            logOrEnsureNanError(TEXT("APawn::FaceRotation about to apply NaN-containing rotation to actor! New:(%s), Current:(%s)"), *NewControlRotation.ToString(), *CurrentRotation.ToString());
        }
#endif

        SetActorRotation(NewControlRotation);
    }
}

對(duì)于這種情況侨舆，可以有幾種方法同步ActorRotation：
1.如果對(duì)Controller Rotation沒有特殊限制，可以設(shè)置 bUseControllerRotationYaw = true舷暮，在需要修改轉(zhuǎn)向時(shí)直接SetControlRotation 即可态罪；
2.不通過Controller的Rotation同步，設(shè)置bUseControllerRotationYaw = false下面，設(shè)置CharacterMovementCompoennt中的bOrientRotationToMovement = true复颈，這個(gè)變量的意思是在移動(dòng)時(shí)自動(dòng)轉(zhuǎn)向你移動(dòng)的方向，可以通過RotationRate控制轉(zhuǎn)向速度沥割；
3.添加自定義變量ActorYaw耗啦，在需要修改時(shí)給服務(wù)器發(fā)RPC。