Create base class for hierachical instanced static mesh, removed Blueprint one

Unreal/CarlaUnreal/Plugins/Carla/Source/Carla/Actor/LevelActor/InstancedStaticMeshActor.cpp

@@ -0,0 +1,17 @@
+// Copyright (c) 2024 Computer Vision Center (CVC) at the Universitat Autonoma
+// de Barcelona (UAB).
+//
+// This work is licensed under the terms of the MIT license.
+// For a copy, see <https://opensource.org/licenses/MIT>.
+
+#include "Carla/Actor/LevelActor/InstancedStaticMeshActor.h"
+#include "Components/HierarchicalInstancedStaticMeshComponent.h"
+
+AInstancedStaticMeshActor::AInstancedStaticMeshActor(const FObjectInitializer& ObjectInitializer)
+  : Super(ObjectInitializer)
+{
+  PrimaryActorTick.bCanEverTick = false;
+  InstancedStaticMeshComponent = CreateDefaultSubobject<UHierarchicalInstancedStaticMeshComponent>("InstancedStaticMeshComponent");
+  
+}
+

Unreal/CarlaUnreal/Plugins/Carla/Source/Carla/Actor/LevelActor/InstancedStaticMeshActor.h

@@ -0,0 +1,32 @@
+// Copyright (c) 2024 Computer Vision Center (CVC) at the Universitat Autonoma
+// de Barcelona (UAB).
+//
+// This work is licensed under the terms of the MIT license.
+// For a copy, see <https://opensource.org/licenses/MIT>.
+
+#pragma once
+
+#include "CoreMinimal.h"
+
+#include "InstancedStaticMeshActor.generated.h"
+
+
+class UHierarchicalInstancedStaticMeshComponent;
+
+UCLASS()
+class CARLA_API AInstancedStaticMeshActor : public AActor
+{
+  GENERATED_BODY()
+
+public:
+  AInstancedStaticMeshActor(const FObjectInitializer &ObjectInitializer);
+
+  UFUNCTION(BlueprintPure, Category="Getter")
+  UHierarchicalInstancedStaticMeshComponent* GetInstancedStaticMeshComponent(){
+    return InstancedStaticMeshComponent;
+  }
+
+protected:
+  UPROPERTY(VisibleAnywhere, Category="Components")
+  UHierarchicalInstancedStaticMeshComponent* InstancedStaticMeshComponent;
+};

Unreal/CarlaUnreal/Plugins/Carla/Source/Carla/BlueprintLibary/MapGenFunctionLibrary.cpp

@@ -12,6 +12,8 @@
 #include "StaticMeshAttributes.h"
 #include "RenderingThread.h"
 #include "PhysicsEngine/BodySetup.h"
+#include "Engine/StaticMeshActor.h"
+#include "Carla/Actor/LevelActor/InstancedStaticMeshActor.h"
 #if WITH_EDITOR
 #include "Editor/EditorEngine.h"
 #include "Editor/Transactor.h"
@@ -236,3 +238,37 @@ void UMapGenFunctionLibrary::CleanupGEngine(){
   }
 #endif
 }
+
+void UMapGenFunctionLibrary::ChangeStaticMeshesInTheLevelForInstancedStaticMeshes(UWorld* World, int MinNumOfInstancesToBeChanged)
+{
+  TArray<AActor*> FoundActors;
+  UGameplayStatics::GetAllActorsOfClass(World,  AStaticMeshActor::StaticClass(), FoundActors);
+  TMap<UStaticMesh*, TArray<AStaticMeshActor*>> ActorsToCheckIfReplacedMap;
+  for(AActor* CurrentActor : FoundActors )
+  {
+    AStaticMeshActor* CurrentStaticMeshActor = Cast<AStaticMeshActor>(CurrentActor);
+    UStaticMeshComponent* CurrentStaticMeshComponent = CurrentStaticMeshActor->GetStaticMeshComponent();
+    UStaticMesh* CurrentStaticMesh = CurrentStaticMeshComponent->GetStaticMesh();
+    TArray<AStaticMeshActor*>& Instances = ActorsToCheckIfReplacedMap.FindOrAdd(CurrentStaticMesh);
+    Instances.Add(CurrentStaticMeshActor);
+  }
+
+  for(auto CurrentPair : ActorsToCheckIfReplacedMap)
+  {
+    if(CurrentPair.Value.Num() > MinNumOfInstancesToBeChanged)
+    {
+      TArray<FTransform> TransformsToBeInstanced;
+      for( AStaticMeshActor* SMActor : CurrentPair.Value )
+      {
+        TransformsToBeInstanced.Add(SMActor->GetActorTransform());
+      }
+    
+      AInstancedStaticMeshActor* InstancedStaticMeshActor = World->SpawnActor<AInstancedStaticMeshActor>();
+      if(InstancedStaticMeshActor)
+      {
+        InstancedStaticMeshActor->GetInstancedStaticMeshComponent()->SetStaticMesh(CurrentPair.Key);
+        InstancedStaticMeshActor->GetInstancedStaticMeshComponent()->AddInstances(TransformsToBeInstanced, false, true);
+      }
+    }
+  }
+}

Unreal/CarlaUnreal/Plugins/Carla/Source/Carla/BlueprintLibary/MapGenFunctionLibrary.h

@@ -51,4 +51,9 @@ public:
 
   UFUNCTION(BlueprintCallable)
   static void CleanupGEngine();
+
+  // This function will count instances of each static mesh in the level, if there are > MinNumOfInstancesToBeChanged they will be changed by instanced static meshes 
+  // to reduce draw calls
+  UFUNCTION(BlueprintCallable)
+  static void ChangeStaticMeshesInTheLevelForInstancedStaticMeshes(UWorld* World, int MinNumOfInstancesToBeChanged = 20);
 };