How do you load multiple assets from one AssetLoader?

[MrGVSV]

For example, say I have a config file:

// config.ron

(
  texture: "textures/foo.png"
)

And I want to load this in as an Asset using a custom AssetLoader. How do I also load the texture (or any other sub-assets) along with it?

[MrGVSV]

I think I found a possible solution:

impl AssetLoader for CustomAssetLoader {
	fn load<'a>(
		&'a self,
		bytes: &'a [u8],
		load_context: &'a mut LoadContext,
	) -> BoxedFuture<'a, anyhow::Result<(), anyhow::Error>> {
		Box::pin(async move {
			// Load file
			let config = ron::de::from_bytes::<CustomAssetConfig>(bytes)?;
			let path = Path::new(&config.texture);

                        // Stolen from `ImageTextureLoader`
			let img_bytes = load_context.read_asset_bytes(path.clone()).await?;
			let ext = path.extension().unwrap().to_str().unwrap();
			let dyn_img = Texture::from_buffer(&img_bytes, ImageType::Extension(ext))?;

			// Create asset
			let handle = load_context.set_labeled_asset("foo", LoadedAsset::new(dyn_img));
			let asset = LoadedAsset::new(CustomAsset { texture_handle: handle });
			load_context.set_default_asset(asset);
			Ok(())
		})
	}

	fn extensions(&self) -> &[&str] {
		&["ron"]
	}
}

Is this the best way to go about it? (If so, I'll mark this as the answer)

[stijnfrishert]

I'm pretty new to Bevy myself, but yes, that's how I've got it working, more or less.

I ran into an issue with the sub asset (a texture) not showing up, and someone on Discord told me to use LoadedAsset().with_dependency() . Otherwise the engine doesn't know how to track the relationship, I guess.

[MrGVSV]

Interesting. What does your code look like? Mine works fine like this (but maybe just because it's a super simple example haha).

[MrGVSV]

Actually I think I understand what you mean. Instead of manually loading the texture I can do this:

impl AssetLoader for CustomAssetLoader {
  fn load<'a>(
    &'a self,
    bytes: &'a [u8],
    load_context: &'a mut LoadContext,
  ) -> BoxedFuture<'a, anyhow::Result<(), anyhow::Error>> {
    Box::pin(async move {
      // Load file
      let config = ron::de::from_bytes::<CustomAssetConfig>(bytes)?;
      let path = Path::new(&config.texture);

      // Get the texture handle
      let asset_path = AssetPath::new_ref(path, None);
      let handle = load_context.get_handle(asset_path.clone());

      // Create asset
      let asset = LoadedAsset::new(CustomAsset { texture_handle: handle })
        .with_dependency(asset_path); // <- Mark it as a dependency so the server knows to load it
      load_context.set_default_asset(asset);
      Ok(())
    })
  }

  fn extensions(&self) -> &[&str] {
    &["ron"]
  }
}