bevy_elf 0.0.1

Serializable Bevy asset definitions that resolve string references into Handles
Documentation

bevy_elf

Crates.io docs.rs License

Load and resolve assets that reference other assets by name, in Bevy.

Hand-written asset types use Handle<T>, which isn't serializable. bevy_elf generates a serializable "Def" counterpart of your asset struct — using plain strings in place of Handles — and a FromDef implementation that converts the Def back into your runtime type, resolving each string into a Handle along the way.

// water_animation.ron
(
    frames: [1, 2, 3],
    frame_duration: (secs: 0, nanos: 128000000),
    spritesheet: "water",
)

use bevy_asset::prelude::*;
use bevy_elf::{FromDef, asset_spec};
use std::time::Duration;

#[derive(FromDef, Asset, TypePath)]
struct AnimationAsset {
    frames: Vec<usize>,
    frame_duration: Duration,
    spritesheet: Handle<Spritesheet>,
}

#[derive(FromDef, Asset, TypePath)]
#[asset_spec(base_path = "spritesheets", extension = "ron")]
struct Spritesheet {
    // fields omitted
}

The derive macro generates the Def struct, its Deserialize impl, and the resolution logic that turns "water" into Handle<Spritesheet> by loading spritesheets/water.ron. Register the loader with the RonAssetPlugin:

app.add_plugins((
    RonAssetPlugin::<AnimationAsset>::default(),
    RonAssetPlugin::<Spritesheet>::default(),
));

Why

Bevy assets that reference other assets naturally want to hold a Handle<T>, but Handle isn't something you can put in a .ron/.toml/.json file — there's nothing to point at until the asset is loaded. The usual workaround is writing two versions of every asset type by hand: a serializable "spec" version with string IDs, and a runtime version with Handles, plus the boilerplate to convert between them. bevy_elf generates that boilerplate for you.

Features

Feature Default Adds
macros ✅ The FromDef derive macro and asset_spec attribute (via bevy_elf_macros)
math ✅ FromDef impls for bevy_math types (Vec2, Vec3, Quat, Rect, ...)
image ❌ FromDef impl for bevy_image::TextureAtlasLayout

Without macros, you can still implement FromDef/FromDefWithResolver by hand for full control over the conversion.

More examples

Implicit fields, omitting empty def files, and resolving foreign types (types you don't own, like Handle<Image>) are covered in the crate documentation.

Bevy compatibility

bevy bevy_elf
0.19 0.1

License

Dual-licensed under either

at your option.