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Cannot spawn actor to a position relative to its parent?


I'm a total beginner with unreal and C++, so i'm probably doing things the wrong way...

I'm trying to make a simple 3D platformer / parkour game with C++. For that, i want a "random" urban environnement. The first thing i've made is a building generator, so that i can spawn buildings with "random in range" number of floors.

So, i made a C++ class called Building based on Actor. It contains a scene as root component, a static mesh for the base floor and an arrow for the location of the next floor, it picks a random uint8 in a range and enters a for loop to call a function that spawns instances of other classes (for now only one other class, a simple box with a few spotlights representing a floor, called Floor), and finally spawns a last instance of another class (inherited from the Floor class called Roof, with slightly different graphics, so that i know which is which). So far, everything works as expected, when i spawn a Building, i get a building with a random number of floors, and a roof.

So i went further, with a Cell class, and it works the same way. It contains a scene as root component, a few static meshes to make roads, and arrows to spawn Buildings. The problem is that when i spawn a Cell, my base floors are placed as expected, on their repective arrows, but all the floors of all the buildings don't move with their base floor. I've attached what i get with a 4 Buildings Cell : 4 Buildings Cell

Here are relevant parts of my code in Building.cpp:

          // Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
         PrimaryActorTick.bCanEverTick = false;
             //Create Scene
             Scene = CreateDefaultSubobject<USceneComponent>(TEXT("Scene"));
             RootComponent = Scene;
             // Create Meshes
             WallMesh = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("Wall Mesh"));
             static ConstructorHelpers::FObjectFinder<UStaticMesh> StaticMeshOb_building(TEXT("StaticMesh'/Game/Geometry/Meshes/BuildingMesh.BuildingMesh'"));
             if (StaticMeshOb_building.Object) WallMesh->SetStaticMesh(StaticMeshOb_building.Object);
             static ConstructorHelpers::FObjectFinder<UMaterial> MaterialOb_building(TEXT("Material'/Game/StarterContent/Materials/M_Concrete_Tiles.M_Concrete_Tiles'"));
             if (MaterialOb_building.Object) WallMesh->SetMaterial(0, MaterialOb_building.Object);
             FloorMesh = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("Floor Mesh"));
             if (StaticMeshOb_building.Object) FloorMesh->SetStaticMesh(StaticMeshOb_building.Object);
             if (MaterialOb_building.Object) FloorMesh->SetMaterial(0, MaterialOb_building.Object);
             // Attach them
             WallMesh->SetRelativeLocation(FVector(0, 0, 150));
             WallMesh->SetRelativeScale3D(FVector(18, 18, 3));
             FloorMesh->SetRelativeLocation(FVector(0, 0, -10));
             FloorMesh->SetRelativeScale3D(FVector(20, 20, 0.1));
             // Create Arrow for next floor
             NextFloor = CreateDefaultSubobject<UArrowComponent>(TEXT("Next Floor"));
             NextFloor->SetRelativeLocation(FVector(0, 0, 300));
         // other things like that not shown
         /** We build enough floors to match our NumberOfFloors */
         void ABuilding::BuildFloors(uint8 Number)
             // The base floor is part of the Building so it's already here.
             // We set the position of the next floor to our arrow position.
             UArrowComponent* Next = NextFloor;
             // We have to check if we have to build more floors before the roof.
             if (Number > 2)
                 // Now we build the next floors starting with that position
                 for (int i = 0; i < Number - 2; ++i)
                     // And we set Next to the next floor position as we build a new floor
                     Next = BuildFloor(Next);
             // Finally, build the roof
         /** We build an intermediate floor from its position, giving back the next one's position*/
         UArrowComponent* ABuilding::BuildFloor(UArrowComponent* Position)
             auto NewFloor = Cast<ABuildingFloor>(UGameplayStatics::BeginDeferredActorSpawnFromClass(this, ABuildingFloor::StaticClass(), Position->GetRelativeTransform(),ESpawnActorCollisionHandlingMethod::Undefined,this));
             if (NewFloor != nullptr)
                 UGameplayStatics::FinishSpawningActor(NewFloor, Position->GetRelativeTransform());
                 NextFloor->AttachToComponent(Position, FAttachmentTransformRules::SnapToTargetIncludingScale);
                 Position = NewFloor->GetNextFloorArrow();
             return Position;

Product Version: UE 4.14
cell.png (1.4 MB)
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asked Jan 07 '17 at 06:06 PM in C++ Programming

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