Actor Role and Remote Role

Determine how much control this game instance has over an actor.

Actor Role and Remote Role

In networked gameplay, an actor's role and remote role determine which machine has the authority to change the actor's state and perform remote procedure calls. These properties help you answer the following questions about an actor in your multiplayer game:

  • Is this actor replicated or not?
  • Who has authority over this actor?
  • What is the replication role for this actor?

Actor role and remote role are not the same as ownership! For more information, see Actors and their Owning Connections.

View an Actor's Role and Remote Role

You can see the current role and remote role of an actor in the Unreal Editor's Details panel:

An actor's role and remote role can also be obtained in C++ or Blueprints.

Get Actor's Role

To determine how much control the local machine has over this actor, call AActor::GetLocalRole:

AMyActor* MyActor;
...
// Once you have a valid Actor pointer...
const ENetRole LocalRole = MyActor->GetLocalRole();
// LocalRole contains the Actor's Role
...

Get Actor's Remote Role

To determine how much control a remote machine has over this actor, call AActor::GetRemoteRole:

AMyActor* MyActor;
...
// Once you have a valid Actor pointer...
const ENetRole RemoteRole = MyActor->GetRemoteRole();
// RemoteRole contains the Actor's RemoteRole
...

Actor Role States

Actor role and remote role are represented by a state of the ENetRole enumeration class (defined in EngineTypes.h). The following table lists and describes these states:

Net Role State Description
ROLE_None No role. This actor is not replicated.
ROLE_SimulatedProxy Simulated proxy of this actor. This actor simulates the true state but has no authority to change the state or call remote functions.
ROLE_AutonomousProxy Autonomous proxy of this actor. This actor simulates the true state and has the authority to change the state and call remote functions.
ROLE_Authority Authoritative control of this actor. This actor holds the true state for networking and has the authority to change the state and call functions. This actor is also in charge of keeping track of property changes and replicating them to connected clients.

Matrix of Roles for Client-Server

Unreal Engine uses the client-server model for networking. As a result, the server always has authority over replicated actors. This means that only the server should ever see ROLE_Authority for replicated actors. Non-replicated actors can have a local role of ROLE_Authority on clients and a remote role of ROLE_None.

The following table provides a matrix of local role and remote role, whether a server or client is witnessing this role combination, and a description of what this combination means:

Local Role Remote Role Server or Client Description
ROLE_Authority ROLE_AutonomousProxy Server This actor pawn is controlled by one of the connected clients.
ROLE_AutonomousProxy ROLE_Authority Client This actor pawn is controlled by this connected client.
ROLE_SimulatedProxy ROLE_Authority Client This actor pawn is controlled by one of the other connected clients.

Replicated actors that are not controlled by any client can also have this role combination.

ROLE_Authority ROLE_None Client This is a non-replicated actor.

Actor Replication Simulation

Servers do not replicate all actors every update because that would take too much bandwidth and CPU resources. Instead, the server replicates actors at the frequency specified on the AActor::NetUpdateFrequency property. This means that some time passes on the client between actor updates. This could result in actors with a character movement component looking choppy and sporadic. To compensate for this, the client simulates character movement between updates.

For more information about replication simulation and character movement, see Networked Movement in the Character Movement Component documentation.

Role and Remote Role Reference

Functions

Name Description
CopyRemoteRoleFrom Copy remote role from another actor and add this actor to the list of network actors if necessary.
ExchangeNetRoles Swap role and remote role if on client.
GetLocalRole Return how much control the local machine has over this actor.
GetRemoteRole Return how much control the remote machine has over this actor.
GetRolePropertyName Get the property name for role.
GetTearOff If true, this actor is no longer replicated to new clients and is "torn off" (becomes ENetRole::ROLE_Authority) on clients to which it was being replicated.
PostNetReceiveRole Called immediately after a new role is received from the remote machine.
SetRemoteRoleForBackwardsCompat Used in the constructor of classes that must set the remote role for backwards compatibility purposes.
SetRole Set the value of role without causing other side effects to this instance.
SwapRoles Swap the role and remote role for this actor.

Use caution and only call this function if you understand the side effects.

Properties

Name Description
bExchangedRoles Whether role and remote role have been exchanged on the client.
  • programming
  • networking
  • role
  • remote role
  • simulated
  • autonomous
  • authority

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