ExtendedMaterials no longer applied after visibility change

[secretlyagoblin]

Bevy version

16.0 (same behaviour observed on 16.1)

AdapterInfo { name: "GeForce GTX 660 Ti", vendor: 4318, device: 4483, device_type: DiscreteGpu, driver: "NVIDIA", driver_info: "456.71", backend: Vulkan }

What you did

I came across a rendering issue with custom materials and asked for help in the discussion tab

Then to try to isolate the issue, I forked and added to the original Extended Material example, adding a system that toggled the visibility on and off.

What went wrong

When I run the example, the custom rendering is applied correctly.

After I hit spacebar twice, hiding the entity and then showing it again, the material is black.

2025-07-17.11-30-29.mp4

Additional information

In my original discussion, I also observed that the extended material properties are not applied if the entity in question is outside of the view frustum of the camera, although I can't be sure of the specifics of that.

[alice-i-cecile]

This is almost certainly a "retained render world" bug, where we're not properly updating some cache.

[janis-bhm]

This is not a bug in bevy but a logic error that isn't immediately obvious:
The DirectionalLight spawns with a Visibility::Inherited as a required component, and since Visibility::Inherited is !Visibility::Visible it get's set to Visible while the sphere gets set to Hidden in the toggle_vis system.
Then, the next time the system runs, the light is set to Hidden and the sphere is set to Visible, but renders as black because the light is hidden.

I can see the sphere after pressing space if I use Visibility::toggle_visible_hidden() or make the query somehow unique to the sphere:

fn toggle_vis(
    mut commands: Commands,
    kbd: Res<ButtonInput<KeyCode>>,
    q: Query<(Entity, &Visibility), With<SphereMarker>>,
) {
    if kbd.just_pressed(KeyCode::Space) {
        for (e, vis) in q.iter() {
            if *vis == Visibility::Visible {
                commands.entity(e).insert(Visibility::Hidden);
            } else {
                commands.entity(e).insert(Visibility::Visible);
            }
        }
    }
}

would be nice if the docs would make it easier to see required components right away when looking up a type like they do with the component or resource traits I guess.

[alice-i-cecile]

Good investigation, thank you very much. Removing from the milestone, but I would be very happy to hear design ideas on how to make this less error-prone.

[secretlyagoblin]

Thanks very much for the investigation, apologies for the gap in the logic, obvious in hindsight - I’ll reiterate that this was an attempt to isolate a different issue, (inadequately, clearly): #20150

I’ll try and make a proper replication. I’m still convinced something weird is happening.