skinned_mesh_culling.md

---

title: Improved Skinned Mesh Culling
authors: ["@greeble-dev"]
pull_requests: [21837]

---

Skinned meshes can now update their bounds from joint positions. This mostly fixes issues like #4971, where meshes would disappear at certain camera angles.

TODO: Maybe add the video from the PR here?

If you load your skinned meshes from glTFs then you don't need to make any changes - the new behavior is automatically enabled.

If you create your own skinned meshes, you'll need to call Mesh::generate_skinned_mesh_bounds or Mesh::with_generated_skinned_bounds and add a DynamicSkinnedMeshBounds component to your mesh entity.

let mut mesh: Mesh = ...;
mesh.generate_skinned_mesh_bounds()?;
 
entity.insert((
    Mesh3d(meshes.add(mesh)),
    DynamicSkinnedMeshBounds,
));

The new behavior is reliable for meshes that only use skinning. But it doesn't account for morph targets, vertex shaders, or anything else that modifies vertex positions.

If you don't want the new behavior and you load your skinned meshes from glTFs, set GltfPlugin::skinned_mesh_bounds_policy to GltfSkinnedMeshBoundsPolicy::BindPose.

app.add_plugins(DefaultPlugins.set(GltfPlugin {
    skinned_mesh_bounds_policy: GltfSkinnedMeshBoundsPolicy::BindPose,
    ..default()
}))

There's also a GltfSkinnedMeshBoundsPolicy::NoFrustumCulling option if you prefer to entirely disable culling for skinned meshes.

If you want to visualize the bounds, enable these gizmos:

fn toggle_skinned_mesh_bounds(mut config: ResMut<GizmoConfigStore>) {
    // Toggle drawing of the per-mesh `Aabb` component that's used for culling.
    config.config_mut::<AabbGizmoConfigGroup>().1.draw_all ^= true;
    // Toggle drawing of the per-joint AABBs used to update the `Aabb` component.
    config.config_mut::<SkinnedMeshBoundsGizmoConfigGroup>().1.draw_all ^= true;
}

Or you can load a glTF into the scene viewer example and press j and b to enable the visualizations.

cargo run --example scene_viewer --features "free_camera" -- "path/to/your.gltf"

If you were using bevy_mod_skinned_aabb, see Bevy 0.19 and bevy_mod_skinned_aabb for how to upgrade.