Download

Accessing static Game Data: DataAssets, ObjectLibrary, AssetManager, AssetRegistry

Development Discussion C++ Programming
#1

Hi, I’m loading some static game data using ObjectLibrary. ObjectLibrary’s comments say it’s better to use AssetManager, but I couldn’t figure out how to accomplish this. AssetRegistry is an editor subsystem and internet FUD said not to use it.

I subclassed UDataAsset adding some properties, then use the editor created those assets in some folders. So /Content/Data/Categories has 4 assets created from Category.h. In my GameState, I’m loading and caching them when accessed with GetCatagories(). That happens in this code:



void ATortillaRushGameState::GetCategories(TArray<UCategory*> &OutCategories)
{
    if (!IsLoaded) LoadGameLibraryCaches();

    for (UCategory* Item : CategoryCache)
    {
       OutCategories.AddUnique(Item);
    }
}

void ATortillaRushGameState::LoadGameLibraryCaches()
{
    TArray<UObject*> OutCache;

    // Categories

    // Clear the current cache
    CategoryCache.Empty();
    // Load Objects into OutCache (LoadObjectsFromPath empties OutCache)
    LoadObjectsFromPath(UCategory::StaticClass(), TEXT("/Game/Data/Categories"), OutCache);
    // Copy Categories into CategoryCache
    for (UObject* Item : OutCache) CategoryCache.AddUnique(Cast<UCategory>(Item));

    IsLoaded = true;

    // Same for other caches

    UE_LOG(LogTemp, Warning, TEXT("Loaded static assets: %d Categories, %d Upgrades, %d Ingredients, %d Recipes"), CategoryCache.Num(), UpgradeCache.Num(), IngredientCache.Num(), RecipeCache.Num());
}

void ATortillaRushGameState::LoadObjectsFromPath(UClass* InBaseClass, FString AssetPath, TArray<UObject*> &OutCache)
{
    OutCache.Empty();

    UObjectLibrary* MyObjectLibrary = UObjectLibrary::CreateLibrary(InBaseClass, true, GIsEditor);

    TArray<FString> AssetPaths;
    AssetPaths.Add(AssetPath);

    MyObjectLibrary->LoadAssetDataFromPaths(AssetPaths);

    // Query Results
    TArray<FAssetData> AssetData;
    MyObjectLibrary->GetAssetDataList(AssetData);

    // Cache assets with Sync Load
    for (FAssetData AssetDatum : AssetData)
    {
       OutCache.AddUnique(AssetDatum.GetAsset());
    }
}

ObjectLibrary appears to work, but I ran all over the county trying to get AssetManager to work using PrimaryDataAsset and failed.

Did I misunderstand AssetManager’s use or purpose? I didn’t understand how to select the class (UCategory), or the path, or how to get the objects out. How could I get this to work with AssetManager?

Would AssetRegistrywork outside the editor? This seems like a handy AssetRegistry example.

Thanks for your help!

#2

Bump does anyone use static data in their games? Or do you design it into the actors themselves?

#3

If you’re trying to load blueprint assets, it works a little bit differently



TArray<FAssetData>AssetData;

const FAssetRegistryModule &AssetRegistry = FModuleManager::LoadModuleChecked<FAssetRegistryModule>("AssetRegistry");

AssetRegistry.Get().GetAssetsByClass( UBlueprint::StaticClass()->GetFName() , AssetData , **true** );

for (auto &myData : AssetData) {

    UBlueprint* BP = GetBlueprintFromCDO( myData.GetAsset() );

    /// ..
}

“true” param in GetAssetsByClass() is an important thing to note there.
And there’s no reason why this wouldn’t work outside editor, AssetRegistry is a Runtime module.