🧪 Bone attachments

[hukasu]

Objective

Starts work on #17114

Solution

Create a new crate bevy_bone_attachments and implement a extension trait on EntityCommands to allow attaching a new Scene to an Entity. The command then collects all AnimationTargets of the entity and copies it to the new Scene.

This is very early and only includes the above method, the new crate can also be included on an existing crate.

Testing

• New example

Showcase

Bone attachments allow you to attach a mesh to another, think a character holding a weapon, or customizable clothing.

Experimental: The current state only allows attaching new scenes into models, and requires that the parent entity is already fully loaded (if it is also a scene, after its SceneInstance is ready) and have matching AnimationTargetIds.

Screencast_20250312_094221.webm

Use Guide

use bevy_bone_attachments::scene::SceneAttachmentExt;

// This requires that the parent is already fully loaded, and there is only a warning if it is not
commands
    .entity(parent)
    .attach_scene(
        asset_server.load_with_settings(
            GltfAssetLabel::Scene(0).from_asset("attachment.glb"),
            |settings: &mut GltfLoaderSettings| { settings.include_animation_target_ids = true; }
    ));

[hukasu]

@alice-i-cecile any template on how to make the release note?

[alice-i-cecile]

@alice-i-cecile any template on how to make the release note?

We're kind of in flux right now, but for now, putting a # Showcase section in the PR would be really helpful. The key points to hit are:

• what new feature was introduced?
• why is it important?
• very briefly, how do you use it?

[viridia]

Looks good generally. Note to @alice-i-cecile : this PR solves one of the two use cases mentioned in the original issue, so unless we want to split it into two separate tickets, it should not close the issue once merged.

[hukasu]

Looks good generally. Note to @alice-i-cecile : this PR solves one of the two use cases mentioned in the original issue, so unless we want to split it into two separate tickets, it should not close the issue once merged.

that is why i wrote Starts work on #17114 instead of Closes

[hukasu]

@alice-i-cecile given how early this is I think it is best to add Needs design

[pcwalton]

Can someone help me understand why we can't just use BSN overrides for this? BSN should have the ability to say "I want to load scene X, but add my own custom entity as a child of object Y". That's core to the concept of what overrides are. Once we do that, this feature should naturally fall out, no?

[hukasu]

@pcwalton for skinned meshes there are other things needed for it to work, not just parenting, I'm preparing another model to actually show that this works for skinned meshes