Actor Replication Net Relevancy (#1348)

* Added Net Relevancy check to actor replication prioritization

* Addressing PR Comments

* Update Comments

* Update CHANGELOG.md

* PR Comments

* Update SpatialGDK/Source/SpatialGDK/Public/SpatialGDKSettings.h

Co-Authored-By: improbable-valentyn <32096431+improbable-valentyn@users.noreply.github.com>

* Update SpatialNetDriver.cpp

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Visual Studio 2019 is now supported.
 - Added toolbar and commandlet options to delete the schema database.
 - Added a check for schema and snapshot before attempting to start a local deployment. If either are missing then an error message will be displayed.
+- Added optional net relevancy check in replication prioritization. If enabled, an actor will only be replicated if IsNetRelevantFor is true for one of the connected client's views.
 
 ### Bug fixes:
 - Fixed an issue that could cause multiple Channels to be created for an Actor.

SpatialGDK/Source/SpatialGDK/Private/EngineClasses/SpatialNetDriver.cpp

@@ -689,12 +689,24 @@ void USpatialNetDriver::OnOwnerUpdated(AActor* Actor)
 #if WITH_SERVER_CODE
 
 // Returns true if this actor should replicate to *any* of the passed in connections
-static FORCEINLINE_DEBUGGABLE bool IsActorRelevantToConnection(const AActor* Actor, const TArray<FNetViewer>& ConnectionViewers)
+static FORCEINLINE_DEBUGGABLE bool IsActorRelevantToConnection(const AActor* Actor, UActorChannel* ActorChannel, const TArray<FNetViewer>& ConnectionViewers)
 {
-	// SpatialGDK: Currently we're just returning true as a worker replicates all the known actors in our design.
-	// We might make some exceptions in the future, so keeping this function.
-	// TODO: UNR-837 Start using IsNetRelevantFor again for relevancy checks rather than returning true.
-	return true;
+	// An actor without a channel yet will need to be replicated at least
+	// once to have a channel and entity created for it
+	if (ActorChannel == nullptr)
+	{
+		return true;
+	}
+
+	for (const auto& Viewer : ConnectionViewers)
+	{
+		if (Actor->IsNetRelevantFor(Viewer.InViewer, Viewer.ViewTarget, Viewer.ViewLocation))
+		{
+			return true;
+		}
+	}
+
+	return false;
 }
 
 // Returns true if this actor is considered dormant (and all properties caught up) to the current connection
@@ -803,6 +815,8 @@ int32 USpatialNetDriver::ServerReplicateActors_PrioritizeActors(UNetConnection*
 		AGameNetworkManager* const NetworkManager = World->NetworkManager;
 		const bool bLowNetBandwidth = NetworkManager ? NetworkManager->IsInLowBandwidthMode() : false;
 
+		const bool bNetRelevancyEnabled = GetDefault<USpatialGDKSettings>()->UseIsActorRelevantForConnection;
+
 		for (FNetworkObjectInfo* ActorInfo : ConsiderList)
 		{
 			AActor* Actor = ActorInfo->Actor;
@@ -826,12 +840,10 @@ int32 USpatialNetDriver::ServerReplicateActors_PrioritizeActors(UNetConnection*
 
 			UE_LOG(LogSpatialOSNetDriver, Verbose, TEXT("Actor %s will be replicated on the catch-all connection"), *Actor->GetName());
 
-			// SpatialGDK: Here, Unreal does initial relevancy checking and level load checking.
-			// We have removed the level load check because it doesn't apply.
-			// Relevancy checking is also mostly just a pass through, might be removed later.
-			if (!IsActorRelevantToConnection(Actor, ConnectionViewers))
+			// Check actor relevancy if Net Relevancy is enabled in the GDK settings
+			if (bNetRelevancyEnabled && !IsActorRelevantToConnection(Actor, Channel, ConnectionViewers))
 			{
-				// If not relevant (and we don't have a channel), skip
+				// Early out and do not replicate if actor is not relevant
 				continue;
 			}
 

SpatialGDK/Source/SpatialGDK/Private/SpatialGDKSettings.cpp

@@ -19,6 +19,7 @@ USpatialGDKSettings::USpatialGDKSettings(const FObjectInitializer& ObjectInitial
 	, HeartbeatTimeoutSeconds(10.0f)
 	, ActorReplicationRateLimit(0)
 	, EntityCreationRateLimit(0)
+	, UseIsActorRelevantForConnection(false)
 	, OpsUpdateRate(1000.0f)
 	, bEnableHandover(true)
 	, MaxNetCullDistanceSquared(900000000.0f) // Set to twice the default Actor NetCullDistanceSquared (300m)

SpatialGDK/Source/SpatialGDK/Public/SpatialGDKSettings.h

@@ -72,6 +72,13 @@ class SPATIALGDK_API USpatialGDKSettings : public UObject
 	UPROPERTY(EditAnywhere, config, Category = "Replication", meta = (ConfigRestartRequired = false, DisplayName = "Maximum entities created per tick"))
 	uint32 EntityCreationRateLimit;
 
+	/**
+	 * When enabled, only entities which are in the net relevancy range of player controllers will be replicated to SpatialOS.
+	 * This should only be used in single server configurations. The state of the world in the inspector will no longer be up to date.
+	 */
+	UPROPERTY(EditAnywhere, config, Category = "Replication", meta = (ConfigRestartRequired = false, DisplayName = "Only Replicate Net Relevant Actors"))
+	bool UseIsActorRelevantForConnection;
+
 	/**
 	* Specifies the rate, in number of times per second, at which server-worker instance updates are sent to and received from the SpatialOS Runtime.
 	* Default:1000/s