Libgdx Asset Manager

libGDX AssetManager

Quick reference for com.badlogic.gdx.assets.AssetManager. Covers loading, retrieval, disposal, reference counting, loading screens, parameters, custom loaders, and error handling.

Core Concepts

load() queues an asset. Nothing is loaded until update() or finishLoading() is called.

load() → queues request
update() → processes one step per call, returns true when ALL done
finishLoading() → blocks until ALL queued assets are loaded
finishLoadingAsset(name) → blocks until ONE specific asset is loaded, returns it
get() → retrieves a loaded asset (throws if not loaded)
unload() → decrements ref count, disposes at zero
dispose() → disposes ALL assets and kills the executor

There is no loadSync() method. Do not invent one.

Constructors

AssetManager manager = new AssetManager();                              // InternalFileHandleResolver, all default loaders
AssetManager manager = new AssetManager(resolver);                      // custom resolver, all default loaders
AssetManager manager = new AssetManager(resolver, false);               // custom resolver, NO default loaders

Loading Assets

// Queue assets (nothing loaded yet)
manager.load("texture.png", Texture.class);
manager.load("atlas.atlas", TextureAtlas.class);
manager.load("click.wav", Sound.class);
manager.load("theme.mp3", Music.class);
manager.load("font.fnt", BitmapFont.class);
manager.load("ui.json", Skin.class);

// With parameters
TextureLoader.TextureParameter param = new TextureLoader.TextureParameter();
param.minFilter = TextureFilter.Linear;
param.magFilter = TextureFilter.Linear;
param.genMipMaps = true;
manager.load("texture.png", Texture.class, param);

Retrieving Assets

// After loading is complete:
Texture tex = manager.get("texture.png", Texture.class);

// Without type (unchecked cast — less safe):
Texture tex = manager.get("texture.png");

// Non-throwing variant (returns null if not loaded):
Texture tex = manager.get("texture.png", Texture.class, false);

// Check first:
if (manager.isLoaded("texture.png")) {
    Texture tex = manager.get("texture.png", Texture.class);
}

// Get all assets of a type:
Array<Texture> textures = new Array<>();
manager.getAll(Texture.class, textures);

Calling get() before the asset is loaded throws GdxRuntimeException. Always use isLoaded(), finishLoading(), or check update() return value first.

Loading Screen Pattern

public class LoadingScreen implements Screen {
    private final MyGame game;
    private final AssetManager manager;

    public LoadingScreen(MyGame game) {
        this.game = game;
        this.manager = game.manager;

        // Queue game assets
        manager.load("game.atlas", TextureAtlas.class);
        manager.load("music.mp3", Music.class);
        manager.load("click.wav", Sound.class);
    }

    @Override
    public void render(float delta) {
        ScreenUtils.clear(0, 0, 0, 1);

        if (manager.update()) {
            // ALL assets loaded — transition
            game.setScreen(new GameScreen(game));
            return;
        }

        float progress = manager.getProgress();  // 0.0 to 1.0
        // Draw progress bar using progress
    }
    // ...
}

update(): Processes one loading step per call. Returns true when all queued assets are done. Must be called every frame.

update(int millis): Loops update() for up to millis milliseconds. May block longer than specified depending on the current asset. On GWT/WebGL, degrades to a single update() call (no threading).

getProgress(): Returns 0.0–1.0. Accounts for partial progress within the current asset, not just completed asset count.

finishLoading(): Blocks the render thread until ALL queued assets are loaded. Only use for small loads or splash screens.

finishLoadingAsset(String fileName): Blocks until the specific asset is loaded and returns it. Useful for loading the loading screen's own assets before entering the async loop:

// Block-load the loading screen's own background
manager.load("loading-bg.png", Texture.class);
Texture bg = manager.finishLoadingAsset("loading-bg.png");

// Now queue game assets (these load asynchronously via update())
manager.load("game.atlas", TextureAtlas.class);

Default Loaders (registered automatically)

Loaders Requiring Manual Registration

TiledMap

manager.setLoader(TiledMap.class, new TmxMapLoader(new InternalFileHandleResolver()));

BaseTiledMapLoader.Parameters params = new BaseTiledMapLoader.Parameters();
params.textureMinFilter = TextureFilter.Linear;
params.textureMagFilter = TextureFilter.Linear;
manager.load("map.tmx", TiledMap.class, params);

AtlasTmxMapLoader is an alternative that loads tiles from a TextureAtlas (requires atlas property in the TMX file).

FreeType Fonts via AssetManager

Two loaders must be registered:

FileHandleResolver resolver = new InternalFileHandleResolver();
manager.setLoader(FreeTypeFontGenerator.class, new FreeTypeFontGeneratorLoader(resolver));
manager.setLoader(BitmapFont.class, ".ttf", new FreetypeFontLoader(resolver));

The .ttf suffix ensures only keys ending in .ttf route to FreetypeFontLoader. The default BitmapFontLoader still handles .fnt keys.

FreetypeFontLoader.FreeTypeFontLoaderParameter param = new FreetypeFontLoader.FreeTypeFontLoaderParameter();
param.fontFileName = "fonts/arial.ttf";       // actual file on disk
param.fontParameters.size = 24;
param.fontParameters.minFilter = TextureFilter.Linear;
param.fontParameters.magFilter = TextureFilter.Linear;
manager.load("arial-24.ttf", BitmapFont.class, param);  // key (must end in .ttf)

The key is a virtual identifier — it does not need to match the real filename. fontFileName points to the actual .ttf file. This enables loading multiple sizes of the same font:

param16.fontFileName = "fonts/arial.ttf";
param16.fontParameters.size = 16;
manager.load("arial-16.ttf", BitmapFont.class, param16);

param32.fontFileName = "fonts/arial.ttf";
param32.fontParameters.size = 32;
manager.load("arial-32.ttf", BitmapFont.class, param32);

The parameter is mandatory. Passing null throws RuntimeException.

Key Parameter Classes

TextureLoader.TextureParameter

BitmapFontLoader.BitmapFontParameter

SkinLoader.SkinParameter

If textureAtlasPath is null, Skin automatically loads <skinname>.atlas (same directory, same base name). The resources map injects objects (e.g., FreeType-generated fonts) into the Skin before JSON parsing:

ObjectMap<String, Object> resources = new ObjectMap<>();
resources.put("default-font", myGeneratedFont);
manager.load("ui.json", Skin.class, new SkinLoader.SkinParameter(resources));

ModelLoader.ModelParameters

ParticleEffectLoader.ParticleEffectParameter

Dependencies

AssetManager resolves dependencies automatically. When you load a TextureAtlas, it loads all referenced Texture files. When you load a Skin, it loads its TextureAtlas. When you load a BitmapFont, it loads its texture page(s).

Do NOT manually load or dispose dependency resources. The AssetManager owns them.

// WRONG — double-managing the atlas
manager.load("game.atlas", TextureAtlas.class);     // loads atlas + its textures
manager.load("sheet.png", Texture.class);            // if sheet.png is IN the atlas, this creates a conflict

// RIGHT — let the atlas manage its textures
manager.load("game.atlas", TextureAtlas.class);
// Access textures through the atlas, not directly

Reference Counting

Loading the same asset path and type twice increments its reference count:

manager.load("click.wav", Sound.class);   // ref count will be 1
manager.load("click.wav", Sound.class);   // ref count will be 2 (not loaded twice)
manager.finishLoading();

manager.getReferenceCount("click.wav");   // returns 2

manager.unload("click.wav");              // ref count → 1 (still alive)
manager.unload("click.wav");              // ref count → 0 (disposed)

Loading the same path with a DIFFERENT type throws GdxRuntimeException immediately.

unload() behavior:

• Decrements ref count. If ref count reaches 0, disposes the asset.
• Recursively unloads dependencies (each checks its own ref count).
• Can also cancel assets that are queued but not yet loaded.
• Throws GdxRuntimeException if the asset is not found.

Disposal

Where to call dispose(): In Game.dispose(), not in Screen.dispose(). Disposing the AssetManager in a Screen destroys all assets, breaking other screens.

public class MyGame extends Game {
    public AssetManager manager;

    @Override
    public void create() {
        manager = new AssetManager();
        setScreen(new LoadingScreen(this));
    }

    @Override
    public void dispose() {
        getScreen().dispose();
        manager.dispose();      // disposes ALL loaded assets
    }
}

Error Handling

manager.setErrorListener(new AssetErrorListener() {
    @Override
    public void error(AssetDescriptor asset, Throwable throwable) {
        Gdx.app.error("Assets", "Failed to load: " + asset.fileName, throwable);
    }
});

When an asset fails during update():

1. The failed task is removed.
2. Dependencies loaded for the failed asset are unloaded.
3. All remaining tasks in the current task stack are cleared.
4. If an AssetErrorListener is set: error() is called. Loading continues (future update() calls process remaining queued assets).
5. If NO listener is set: throws GdxRuntimeException, crashing the app.

Always set an error listener in production.

Custom Loaders

// SynchronousAssetLoader — everything on render thread
public class JsonDataLoader extends SynchronousAssetLoader<JsonData, JsonDataLoader.Params> {
    public JsonDataLoader(FileHandleResolver resolver) { super(resolver); }

    @Override
    public JsonData load(AssetManager manager, String fileName, FileHandle file, Params parameter) {
        return new JsonData(file.readString());
    }

    @Override
    public Array<AssetDescriptor> getDependencies(String fileName, FileHandle file, Params parameter) {
        return null;  // no dependencies
    }

    static public class Params extends AssetLoaderParameters<JsonData> {}
}

// Register
manager.setLoader(JsonData.class, new JsonDataLoader(new InternalFileHandleResolver()));

setLoader(type, suffix, loader) registers a loader for a specific file suffix. The longest matching suffix wins. Pass null for suffix to register as the default loader for that type.

AsynchronousAssetLoader

Two abstract methods: loadAsync() (worker thread, no GL) and loadSync() (render thread, GL available). Temporary state between these two methods must be nulled at the start of loadAsync() to prevent stale data from a previous load cycle.

Android Resume

Texture.setAssetManager(manager);

Call this once after creating the AssetManager. On Android resume, managed textures loaded via AssetManager are reloaded on a separate thread. Without this call, the default managed texture mechanism still works but uses the render thread.

FileHandleResolver

Common Mistakes

1. Calling get() before loading is complete — load() only queues. You must call update() until it returns true, or use finishLoading()/finishLoadingAsset(), before calling get().
2. Inventing loadSync() — This method does not exist on AssetManager. Use finishLoadingAsset(fileName) to block on a single asset.
3. Disposing assets manually AND via AssetManager — Calling texture.dispose() on an AssetManager-owned asset corrupts internal state. Always use manager.unload() instead.
4. Disposing AssetManager in Screen.dispose() — This destroys all assets across all screens. Dispose AssetManager only in Game.dispose().
5. Using finishLoading() for large asset sets — Blocks the render thread, causing ANR on Android. Use update() in render() for async loading.
6. Forgetting update() entirely — Calling load() then get() without any update() or finishLoading() in between. Nothing is loaded yet.
7. Manually loading dependency resources — Loading a texture that belongs to a TextureAtlas via a separate load() call creates a duplicate. Let the AssetManager resolve dependencies.
8. Not setting an error listener — Without one, a single failed asset crashes the app via GdxRuntimeException.
9. Making AssetManager static — On Android, static fields survive Activity restarts, causing stale references to disposed native resources. Use an instance field on your Game class.
10. Forgetting to register FreeType loaders — Both FreeTypeFontGeneratorLoader and FreetypeFontLoader must be registered. The load key must end in .ttf. The FreeTypeFontLoaderParameter is mandatory (not optional).
11. Forgetting to register TmxMapLoader — TiledMap has no default loader. You must call setLoader(TiledMap.class, new TmxMapLoader(...)) before loading .tmx files.
12. Calling unload() on an asset that was never loaded — Throws GdxRuntimeException. Check with contains() or isLoaded() first if unsure.

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