unreal-networking

Networking - Unreal Engine 5.7

Property Replication

• Use UPROPERTY(Replicated) for properties that need to synchronize
• Use ReplicatedUsing = FunctionName for callback when value changes
• Implement GetLifetimeReplicatedProps() to configure replication

Replication Example

// Header
UPROPERTY(Replicated, ReplicatedUsing = OnRep_Health)
float Health;

UFUNCTION()
void OnRep_Health();

// Cpp
void AMyActor::GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& OutLifetimeProps) const
{
    Super::GetLifetimeReplicatedProps(OutLifetimeProps);
    DOREPLIFETIME(AMyActor, Health);
}

void AMyActor::OnRep_Health()
{
    // Called when Health is replicated
}

RPCs (Remote Procedure Calls)

• Server RPC - Client calls server

  UFUNCTION(Server, Reliable)
  void ServerFireWeapon();
  

• Client RPC - Server calls client

  UFUNCTION(Client, Reliable)
  void ClientShowDamage(float DamageAmount);
  

• NetMulticast - Server calls all clients

  UFUNCTION(NetMulticast, Reliable)
  void MulticastExplode();
  

RPC Validation

• Use WithValidation to validate RPCs:

  UFUNCTION(Server, Reliable, WithValidation)
  void ServerFireWeapon();
  
  bool ServerFireWeapon_Validate() { return true; }
  void ServerFireWeapon_Implementation() { /* code */ }
  

Best Practices

• Minimize replicated data (only what is necessary)
• Use ReplicatedUsing to update UI/local when values change
• Reliable RPCs are guaranteed, unreliable ones can be lost
• Use NetPriority to control replication order
• Consider NetUpdateFrequency to control update frequency
• ALWAYS validate server RPCs to prevent cheating