Asset Saving

Bevy has had an AssetSaver trait since 0.12. However, it was only ever intended for use inside asset processing pipelines, not for saving assets at runtime. This left a frustrating gap: there was no supported way to save a procedurally generated mesh, a baked lightmap, or the output of an in-editor workflow.

Now there is.

save_using_saver lets you save any asset to disk using an AssetSaver implementation of your choice.

1. Building the `SavedAsset`

For simple assets with no sub-assets, use SavedAsset::from_asset:

rust

let main_asset = InlinedBook {
    lines: vec!["Save me!".to_string(), "Please!".to_string()],
};
let saved_asset = SavedAsset::from_asset(&main_asset);

For assets that reference other assets (sub-assets), use SavedAssetBuilder:

rust

let asset_path: AssetPath<'static> = "my/file/path.whatever".into();
let mut builder = SavedAssetBuilder::new(asset_server.clone(), asset_path.clone());

let subasset_1 = Line("howdy".into());
let subasset_2 = Line("goodbye".into());
let handle_1 = builder.add_labeled_asset_with_new_handle(
    "TheFirstLabel", SavedAsset::from_asset(&subasset_1));
let handle_2 = builder.add_labeled_asset_with_new_handle(
    "AnotherOne", SavedAsset::from_asset(&subasset_2));

let main_asset = Book {
    lines: vec![handle_1, handle_2],
};
let saved_asset = builder.build(&main_asset);

SavedAsset borrows rather than owns its assets. That means you can build and save in the same async block — no need to transfer ownership first.

2. Calling `save_using_saver`

rust

save_using_saver(
    asset_server.clone(),
    &MyAssetSaver::default(),
    &asset_path,
    saved_asset,
    &MySettings::default(),
).await.unwrap();

save_using_saver is async; generally, you'll want to spawn it with IoTaskPool::get().spawn(...). You'll also need to implement AssetSaver for MyAssetSaver to define the serialization format.

1. Building the SavedAsset

2. Calling save_using_saver

1. Building the `SavedAsset`

2. Calling `save_using_saver`