UI nodes should ignore RenderLayers

[ickshonpe]

Bevy version

Bevy main

What you did

Added RenderLayers::layer(1) to the text entities in the multiple_windows example.

//! Uses two windows to visualize a 3D model from different angles.

use bevy::{prelude::*, render::camera::RenderTarget, window::WindowRef};
use bevy_render::view::RenderLayers;

fn main() {
    App::new()
        // By default, a primary window gets spawned by `WindowPlugin`, contained in `DefaultPlugins`
        .add_plugins(DefaultPlugins)
        .add_systems(Startup, setup_scene)
        .run();
}

fn setup_scene(mut commands: Commands, asset_server: Res<AssetServer>) {
    // add entities to the world
    commands.spawn(SceneRoot(
        asset_server.load(GltfAssetLabel::Scene(0).from_asset("models/torus/torus.gltf")),
    ));
    // light
    commands.spawn((
        DirectionalLight::default(),
        Transform::from_xyz(3.0, 3.0, 3.0).looking_at(Vec3::ZERO, Vec3::Y),
    ));

    let first_window_camera = commands
        .spawn((
            Camera3d::default(),
            Transform::from_xyz(0.0, 0.0, 6.0).looking_at(Vec3::ZERO, Vec3::Y),
        ))
        .id();

    // Spawn a second window
    let second_window = commands
        .spawn(Window {
            title: "Second window".to_owned(),
            ..default()
        })
        .id();

    let second_window_camera = commands
        .spawn((
            Camera3d::default(),
            Transform::from_xyz(6.0, 0.0, 0.0).looking_at(Vec3::ZERO, Vec3::Y),
            Camera {
                target: RenderTarget::Window(WindowRef::Entity(second_window)),
                ..default()
            },
        ))
        .id();

    let node = Node {
        position_type: PositionType::Absolute,
        top: Val::Px(12.0),
        left: Val::Px(12.0),
        ..default()
    };

    commands.spawn((
        Text::new("First window"),
        node.clone(),
        // Since we are using multiple cameras, we need to specify which camera UI should be rendered to
        TargetCamera(first_window_camera),
        RenderLayers::layer(1),
    ));

    commands.spawn((
        Text::new("Second window"),
        node,
        TargetCamera(second_window_camera),
        RenderLayers::layer(1),
    ));
}

What went wrong

The text labels are not visible.

Additional information

The UI doesn't use Renderlayers instead you set a target camera using the TargetCamera component.

The example above doesn't seem that terrible. The cameras are using render layer 0, so it makes sense they wouldn't display UI nodes using render layer 1.

But if you set the second camera to render layer 1 and remove the TargetCamera from the second text entity both text nodes are now rendered to camera 1 on top of each other. And if you then remove the second camera, the second text node goes invisible. Which all seems like nonsense.

[alice-i-cecile]

See #17402.