How to save property values set in OnConstruction?

Development Programming & Scripting C++
1

Hello,

I’m currently investigating how I can setup a dungeon generation system for our game.

Not a completely procedural dungeon generation, but a serie of rooms created separately, and which would be used by the dungeon manager to populate the level.

What I would like, is to avoid to set up a lot of variables everywhere to know what the rooms look like.

So I first started with a level data class which holds an array of TSubClassOf< ARWCRoom >


UCLASS()
class RWC_API URWCLevelData : public UDataAsset
{
    GENERATED_BODY()

public:

    UPROPERTY( EditAnywhere )
    TArray< TSubclassOf< ARWCRoom > > RoomClassTable;
};

This data asset is given to the ARWCDungeon class, which in its BeginPlay selects the rooms randomly, and connects them:


void ARWCDungeon::BeginPlay()
{
    Super::BeginPlay();

    for ( auto room_class : LevelData->RoomClassTable )
    {
        if ( auto * room = Cast< ARWCRoom >( room_class->GetDefaultObject() ) )
        {
            const auto door_count = room->GetDoorCount();

            UE_LOG( LogRWC, Warning, TEXT( "Door count : %i" ), door_count );
        }
    }
}

To connect the rooms between them, I first need to know how many doors each room has, and the position and rotation of each door too.

I would like these informations to be content-driven. I would like to avoid to have to let the designer first create the room. then fill the relevant properties on the room blueprint.
As a matter of simplicity, I would prefer him to create the room, and let the room blueprint figure out how many doors it contains, and their transforms, so the dungeon blueprint can do its work>

I thought the OnConstruction would be the function to use to update those properties:


UCLASS()
class RWC_API ARWCRoom : public AActor
{
    GENERATED_BODY()

public:

    FORCEINLINE int GetDoorCount() const { return DoorCount; }

    virtual void OnConstruction( const FTransform & transform ) override;

private:

    UPROPERTY( EditAnywhere )
    int DoorCount;
};



void ARWCRoom::OnConstruction( const FTransform & transform )
{
    auto component_array = GetComponentsByClass( UChildActorComponent::StaticClass() );

    DoorCount = 0;

    for ( auto * actor_component : component_array )
    {
        if ( auto *  child_actor_component = Cast< UChildActorComponent > ( actor_component ) )
        {
            if ( auto * door = Cast< ARWCDoor >( child_actor_component->GetChildActor() ) )
            {
                DoorCount++;
            }
        }
    }
}

At this point, the OnConstruction function is called when I edit my room in the editor, and DoorCount has the correct value.

But when I access GetDoorCount() on the CDO of the room, its value remains 0.

Are there any other function I should use to save thoses values in the asset?

Is it possible to have it work the way I would like? Or am I stuck having to let the designers will every values on each blueprint, which is error-prone?

Thanks!

2

Why do you expect CDO to change default values when you edit an instance?

Btw… try that inside objects constructor; but inside:

if (GEngine) {
const auto &World = GetWorld();
if (World) {
// count doors…
}
}

3

My bad about CDO.

I don’t know why I thought it was saved per-instance and not per class…

So I guess I’ll have to let the designers sort the various rooms in seperate lists, depending on their door count

Thanks

4

Based on my painful experience with setting values in onconstruction, you need uproperty() or ufunction(). Not sure if that was the same case with your example.

5

I don’t know. Until I find out a better solution, I will stick with having to sort the rooms myself in separate arrays, depending on their number of doors…