Assets / Custom Asset

Back to examples View in GitHub

Support Warning

WebGPU is currently only supported on Chrome starting with version 113, and only on desktop. If they don't work on your configuration, you can check the WebGL2 examples here.

//! Implements loader for a custom asset type.

use bevy::{
    asset::{AssetLoader, LoadContext, LoadedAsset},
    reflect::{TypePath, TypeUuid},
use serde::Deserialize;

#[derive(Debug, Deserialize, TypeUuid, TypePath)]
#[uuid = "39cadc56-aa9c-4543-8640-a018b74b5052"]
pub struct CustomAsset {
    pub value: i32,

pub struct CustomAssetLoader;

impl AssetLoader for CustomAssetLoader {
    fn load<'a>(
        &'a self,
        bytes: &'a [u8],
        load_context: &'a mut LoadContext,
    ) -> BoxedFuture<'a, Result<(), bevy::asset::Error>> {
        Box::pin(async move {
            let custom_asset = ron::de::from_bytes::<CustomAsset>(bytes)?;

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

fn main() {
        .add_systems(Startup, setup)
        .add_systems(Update, print_on_load)

#[derive(Resource, Default)]
struct State {
    handle: Handle<CustomAsset>,
    printed: bool,

fn setup(mut state: ResMut<State>, asset_server: Res<AssetServer>) {
    state.handle = asset_server.load("data/asset.custom");

fn print_on_load(mut state: ResMut<State>, custom_assets: ResMut<Assets<CustomAsset>>) {
    let custom_asset = custom_assets.get(&state.handle);
    if state.printed || custom_asset.is_none() {

    info!("Custom asset loaded: {:?}", custom_asset.unwrap());
    state.printed = true;