[[https://docs.unrealengine.com/en-US/InteractiveExperiences/Networking/QuickStart/index.html | 原文]]

 * How to add replication to a base Actor [[#1]]
 * How to take advantage of '''Movement Components''' in a network game [[#2]]
 * How to add replication to '''variables''' [[#3]]
 * How to use '''!RepNotifies''' when a variable changes [[#4]]
 * How to use '''Remote Procedure Calls (RPCs)''' in C++ [[#5]]
 * How to check an Actor's '''Network Role''' in order to filter calls that are performed within a function [[#6]]

= #1 and #3 =
<<Anchor(1)>>How to add replication to a base Actor <<BR>>
<<Anchor(3)>>How to add replication to '''variables'''

{{{#!highlight C++
////////////////////////////
// ThirdPersonMPCharacter.h
////////////////////////////
/** The player's current health. When reduced to 0, they are considered dead.*/
UPROPERTY(ReplicatedUsing=OnRep_CurrentHealth)
float CurrentHealth;

/** RepNotify for changes made to current health.*/
UFUNCTION()
void OnRep_CurrentHealth();

/** Property replication */
void GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& OutLifetimeProps) const override;
}}}

{{{#!highlight C++
////////////////////////////
// ThirdPersonMPCharacter.cpp
////////////////////////////

//////////////////////////////////////////////////////////////////////////
// Replicated Properties

void AThirdPersonMPCharacter::GetLifetimeReplicatedProps(TArray <FLifetimeProperty> & OutLifetimeProps) const
{
    Super::GetLifetimeReplicatedProps(OutLifetimeProps);

    //Replicate current health.
    DOREPLIFETIME(AThirdPersonMPCharacter, CurrentHealth);
}
}}}

= #4 and #6 =
<<Anchor(4)>>How to use '''!RepNotifies''' when a variable changes<<BR>>
<<Anchor(6)>>How to check an Actor's '''Network Role''' in order to filter calls that are performed within a function

{{{#!highlight C++
////////////////////////////
// ThirdPersonMPCharacter.h
////////////////////////////

/** Response to health being updated. Called on the server immediately after modification, and on clients in response to a RepNotify*/
void OnHealthUpdate();
}}}

{{{#!highlight C++
////////////////////////////
// ThirdPersonMPCharacter.cpp
////////////////////////////

void AThirdPersonMPCharacter::OnHealthUpdate()
{
    //Client-specific functionality
    if (IsLocallyControlled())
    {
        FString healthMessage = FString::Printf(TEXT("You now have %f health remaining."), CurrentHealth);
        GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Blue, healthMessage);

        if (CurrentHealth <= 0)
        {
            FString deathMessage = FString::Printf(TEXT("You have been killed."));
            GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, deathMessage);
        }
    }

    //Server-specific functionality
    if (GetLocalRole() == ROLE_Authority)
    {
        FString healthMessage = FString::Printf(TEXT("%s now has %f health remaining."), *GetFName().ToString(), CurrentHealth);
        GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Blue, healthMessage);
    }

    //Functions that occur on all machines. 
    /*  
        Any special functionality that should occur as a result of damage or death should be placed here. 
    */
}

void AThirdPersonMPCharacter::OnRep_CurrentHealth()
{
    OnHealthUpdate();
}
}}}

= TakeDamage from APawn =

{{{#!highlight C++
////////////////////////////
// ThirdPersonMPCharacter.h
////////////////////////////

/** Setter for Current Health. Clamps the value between 0 and MaxHealth and calls OnHealthUpdate. Should only be called on the server.*/
UFUNCTION(BlueprintCallable, Category="Health")
void SetCurrentHealth(float healthValue);

/** Event for taking damage. Overridden from APawn.*/
UFUNCTION(BlueprintCallable, Category = "Health")
float TakeDamage( float DamageTaken, struct FDamageEvent const& DamageEvent, AController* EventInstigator, AActor* DamageCauser ) override;
}}}

{{{#!highlight C++
////////////////////////////
// ThirdPersonMPCharacter.cpp
////////////////////////////

void AThirdPersonMPCharacter::SetCurrentHealth(float healthValue)
{
    if (GetLocalRole() == ROLE_Authority)
    {
        CurrentHealth = FMath::Clamp(healthValue, 0.f, MaxHealth);
        OnHealthUpdate();
    }
}

float AThirdPersonMPCharacter::TakeDamage(float DamageTaken, struct FDamageEvent const& DamageEvent, AController* EventInstigator, AActor* DamageCauser)
{
    float damageApplied = CurrentHealth - DamageTaken;
    SetCurrentHealth(damageApplied);
    return damageApplied;
}
}}}
注意：!SetCurrentHealth函数里也调用了!OnHealthUpdate，这是为了确保server和client同时都能调到该函数进而保持Health值一致。这个调用是必须的，因为'''server不会收到!RepNotify'''。