Bevy version

v0.10.0

What you did

• Implemented a system that relies on accurate change tracking via Changed<ComputedVisibility>

fn my_visibility_system(changed_visibility: Query<(Entity, &ComputedVisibility), Changed<ComputedVisibility>>) {
    for (entity, computed_visibility) in query_changed_visibility.iter() {
        info!("Entity {entity:?} visibility changed to {}", computed_visibility.is_visible());
    }
}

What went wrong

• ComputedVisibility is mutated every frame regardless of whether its underlying flags have actually changed
• In the above example, this causes Entity (foo) visibility changed to (bar) to log each frame, instead of when a self / ancestor Visibility component is modified, or when an entity's Aabb passes in / out of the view frustum.

Additional information

This prevents user code from reasoning about changes in ComputedVisibility, necessitating manual per-frame change tracking. This can be achieved by locally caching ComputedVisibility state on a per-entity basis, or checking the state fed into by ComputedVisibility before mutating it, but isn't DRY versus being able to use the built-in machinery.