Repository: bevyengine/bevy
File: examples/3d/skybox.rs (Rust)

Code before:
    // Skip swapping to the same texture. Useful for when ktx2, zstd, or compressed texture support
    // is missing
    if new_index == cubemap.index {
        return;
    }

    cubemap.index = new_index;
    cubemap.image_handle = asset_server.load(CUBEMAPS[cubemap.index].0);
    cubemap.is_loaded = false;
}

fn asset_loaded(
    asset_server: Res<AssetServer>,
    mut images: ResMut<Assets<Image>>,
    mut cubemap: ResMut<Cubemap>,
    mut skyboxes: Query<&mut Skybox>,
) {
    if !cubemap.is_loaded && asset_server.load_state(&cubemap.image_handle).is_loaded() {
        info!("Swapping to {}...", CUBEMAPS[cubemap.index].0);
        let image = images.get_mut(&cubemap.image_handle).unwrap();
        // NOTE: PNGs do not have any metadata that could indicate they contain a cubemap texture,
        // so they appear as one texture. The following code reconfigures the texture as necessary.
        if image.texture_descriptor.array_layer_count() == 1 {
            image
                .reinterpret_stacked_2d_as_array(image.height() / image.width())
                .unwrap();
            image.texture_view_descriptor = Some(TextureViewDescriptor {
                dimension: Some(TextureViewDimension::Cube),
                ..default()
            });
        }

        for mut skybox in &mut skyboxes {
            skybox.image = cubemap.image_handle.clone();
        }

        cubemap.is_loaded = true;
    }
}

fn animate_light_direction(
    time: Res<Time>,
    mut query: Query<&mut Transform, With<DirectionalLight>>,
) {
    for mut transform in &mut query {
        transform.rotate_y(time.delta_secs() * 0.5);
    }
}


Review comment (suggestion):
This is a user-facing example. This should, at the minimum, use expect, and in the best case handle the error/bubble it up.

Code after:
    // Skip swapping to the same texture. Useful for when ktx2, zstd, or compressed texture support
    // is missing
    if new_index == cubemap.index {
        return;
    }

    cubemap.index = new_index;
    cubemap.image_handle = asset_server.load(CUBEMAPS[cubemap.index].0);
    cubemap.is_loaded = false;
}

fn asset_loaded(
    asset_server: Res<AssetServer>,
    mut images: ResMut<Assets<Image>>,
    mut cubemap: ResMut<Cubemap>,
    mut skyboxes: Query<&mut Skybox>,
) {
    if !cubemap.is_loaded && asset_server.load_state(&cubemap.image_handle).is_loaded() {
        info!("Swapping to {}...", CUBEMAPS[cubemap.index].0);
        let image = images.get_mut(&cubemap.image_handle).unwrap();
        // NOTE: PNGs do not have any metadata that could indicate they contain a cubemap texture,
        // so they appear as one texture. The following code reconfigures the texture as necessary.
        if image.texture_descriptor.array_layer_count() == 1 {
            image
                .reinterpret_stacked_2d_as_array(image.height() / image.width())
                .expect("asset should be 2d texture and height will always be evenly divisible with the given layers");
            image.texture_view_descriptor = Some(TextureViewDescriptor {
                dimension: Some(TextureViewDimension::Cube),
                ..default()
            });
        }

        for mut skybox in &mut skyboxes {
            skybox.image = cubemap.image_handle.clone();
        }

        cubemap.is_loaded = true;
    }
}

fn animate_light_direction(
    time: Res<Time>,
    mut query: Query<&mut Transform, With<DirectionalLight>>,
) {
    for mut transform in &mut query {
        transform.rotate_y(time.delta_secs() * 0.5);
    }
}