Extend existing bundle?

[someguynamedjosh]

I have a situation where I want to spawn an entity that is a sprite with a couple of extra components. Right now I am doing it like this:

#[derive(Bundle)]
struct BuildingBundle {
    // Begin sprite bundle...
    pub sprite: Sprite,
    pub mesh: Handle<Mesh>, // TODO: maybe abstract this out
    pub material: Handle<ColorMaterial>,
    pub main_pass: MainPass,
    pub draw: Draw,
    pub visible: Visible,
    pub render_pipelines: RenderPipelines,
    pub transform: Transform,
    pub global_transform: GlobalTransform,
    // End sprite bundle...
    pub pos: BuildingPos,
}

Is there a way to use the existing definition of SpriteBundle and then add BuildingPos to it?

[someguynamedjosh]

I could also do something like this:

#[derive(Bundle)]
struct BuildingBundle {
    pub pos: BuildingPos,
}

fn building_bundles(
    ...
) -> (SpriteBundle, BuildingBundle) {
    ...
}

let (a, b) = building_bundles(...);
commands.spawn(a).with_bundle(b);

If I added a custom trait I could give commands a function like spawn_with_bundles that would accept a tuple of bundles and expand it accordingly. I think that would be ergonomic enough but it would be nicer if there was a built-in solution.

[CleanCut]

Is there a way to use the existing definition of SpriteBundle and then add BuildingPos to it?

From that question, it seems like you're looking to organize logic, not data, so maybe instead of looking to custom data structures, consider using a helper function instead?

fn spawn_building(commands: &mut Commands, ...) {
    ...
    commands.spawn(SpriteBundle {
            material: materials.add(texture_handle.into()),
            ..Default::default()
        })
        .with(BuildingPos { ... });
}

Does that seem like what you were looking for?

[alice-i-cecile]

See #792 and follow-up discussion :) The bundle nesting tech described in #1570 should solve your specific need here.