Attach AWorldObserver sensor to UCarlaEpisode

Unreal/CarlaUE4/Plugins/Carla/Source/Carla/Game/CarlaEpisode.cpp

@@ -17,6 +17,24 @@ UCarlaEpisode::UCarlaEpisode(const FObjectInitializer &ObjectInitializer)
       return ++COUNTER;
     }()) {}
 
+const AWorldObserver *UCarlaEpisode::StartWorldObserver(carla::streaming::MultiStream Stream)
+{
+  UE_LOG(LogCarla, Log, TEXT("Starting AWorldObserver sensor"));
+  check(WorldObserver != nullptr);
+  auto *World = GetWorld();
+  check(World != nullptr);
+  WorldObserver = World->SpawnActorDeferred<AWorldObserver>(
+      AWorldObserver::StaticClass(),
+      FTransform(),
+      nullptr,
+      nullptr,
+      ESpawnActorCollisionHandlingMethod::AlwaysSpawn);
+  WorldObserver->SetEpisode(*this);
+  WorldObserver->SetStream(std::move(Stream));
+  UGameplayStatics::FinishSpawningActor(WorldObserver, FTransform());
+  return WorldObserver;
+}
+
 void UCarlaEpisode::InitializeAtBeginPlay()
 {
   auto World = GetWorld();

Unreal/CarlaUE4/Plugins/Carla/Source/Carla/Game/CarlaEpisode.h

@@ -7,6 +7,7 @@
 #pragma once
 
 #include "Carla/Actor/ActorDispatcher.h"
+#include "Carla/Sensor/WorldObserver.h"
 #include "Carla/Weather/Weather.h"
 
 #include "CarlaEpisode.generated.h"
@@ -93,6 +94,13 @@ public:
     return ActorDispatcher.GetActorRegistry();
   }
 
+  const AWorldObserver *StartWorldObserver(carla::streaming::MultiStream Stream);
+
+  const AWorldObserver *GetWorldObserver() const
+  {
+    return WorldObserver;
+  }
+
 private:
 
   friend class ATheNewCarlaGameModeBase;
@@ -116,4 +124,7 @@ private:
 
   UPROPERTY(VisibleAnywhere)
   AWeather *Weather = nullptr;
+
+  UPROPERTY(VisibleAnywhere)
+  AWorldObserver *WorldObserver = nullptr;
 };

Unreal/CarlaUE4/Plugins/Carla/Source/Carla/Sensor/WorldObserver.h

@@ -8,8 +8,6 @@
 
 #include "GameFramework/Actor.h"
 
-#include "Carla/Game/CarlaEpisode.h"
-
 #include <compiler/disable-ue4-macros.h>
 #include <carla/Optional.h>
 #include <carla/streaming/Stream.h>
@@ -17,6 +15,8 @@
 
 #include "WorldObserver.generated.h"
 
+class UCarlaEpisode;
+
 /// Serializes and sends all the actors in a UCarlaEpisode.
 UCLASS()
 class CARLA_API AWorldObserver : public AActor
@@ -42,6 +42,12 @@ public:
     Stream = std::move(InStream);
   }
 
+  auto GetStreamToken() const
+  {
+    check(Stream.has_value());
+    return (*Stream).token();
+  }
+
   void BeginPlay() final;
 
   void Tick(float DeltaSeconds) final;

Unreal/CarlaUE4/Plugins/Carla/Source/Carla/Server/TheNewCarlaServer.cpp

@@ -138,7 +138,11 @@ void FTheNewCarlaServer::FPimpl::BindActions()
 
   Server.BindSync("get_episode_info", [this]() -> cr::EpisodeInfo {
     RequireEpisode();
-    return {Episode->GetId(), cr::FromFString(Episode->GetMapName())};
+    auto WorldObserver = Episode->GetWorldObserver();
+    if (WorldObserver == nullptr) {
+      WorldObserver = Episode->StartWorldObserver(StreamingServer.MakeMultiStream());
+    }
+    return {Episode->GetId(), cr::FromFString(Episode->GetMapName()), WorldObserver->GetStreamToken()};
   });
 
   Server.BindSync("get_actor_definitions", [this]() {