Named global Z layers for bevy_ui

crates/bevy_dev_tools/src/diagnostics_overlay.rs

@@ -26,7 +26,7 @@ const ROW_COLUMN_GAP: Val = Val::Px(4.);
 /// Padding for cels of the diagnostics overlay
 const DEFAULT_PADDING: UiRect = UiRect::all(Val::Px(4.));
 /// Initial Z-index for the [`DiagnosticsOverlayPlane`]
-pub const INITIAL_DIAGNOSTICS_OVERLAY_PLANE_Z_INDEX: GlobalZIndex = GlobalZIndex(1_000_000);
+pub const INITIAL_DIAGNOSTICS_OVERLAY_PLANE_Z_INDEX: &str = "bevy_dev_tools::diagnostics_overlay";
 /// Alias to shorten the name
 type StandardMaterialAllocator = MaterialAllocatorDiagnosticPlugin<StandardMaterial>;
 
@@ -249,6 +249,13 @@ pub struct DiagnosticsOverlayPlugin;
 
 impl Plugin for DiagnosticsOverlayPlugin {
     fn build(&self, app: &mut App) {
+        app.init_resource::<GlobalZLayers>();
+        let mut layers = app.world_mut().resource_mut::<GlobalZLayers>();
+        let index = layers
+            .get_index(crate::fps_overlay::FPS_OVERLAY_ZINDEX)
+            .or_else(|_| layers.get_index(crate::picking_debug::DEBUG_PICKING_LAYER))
+            .map_or(layers.len(), |index| index as usize);
+        layers.insert(index, INITIAL_DIAGNOSTICS_OVERLAY_PLANE_Z_INDEX.into());
         app.init_resource::<DiagnosticsOverlayStyle>();
         app.configure_sets(Update, DiagnosticsOverlaySystems::Rebuild);
         app.add_systems(PreStartup, build_plane);
@@ -280,7 +287,7 @@ fn build_plane(mut commands: Commands) {
             should_block_lower: false,
             ..Default::default()
         },
-        INITIAL_DIAGNOSTICS_OVERLAY_PLANE_Z_INDEX,
+        GlobalZIndex::new(INITIAL_DIAGNOSTICS_OVERLAY_PLANE_Z_INDEX),
     ));
 }
 

crates/bevy_dev_tools/src/fps_overlay.rs

@@ -20,7 +20,8 @@ use bevy_text::{RemSize, TextColor, TextFont, TextSpan};
 use bevy_time::common_conditions::on_timer;
 use bevy_ui::{
     widget::{Text, TextUiWriter},
-    ComputedUiRenderTargetInfo, FlexDirection, GlobalZIndex, Node, PositionType, Val,
+    ComputedUiRenderTargetInfo, FlexDirection, GlobalZIndex, GlobalZLayers, Node, PositionType,
+    Val,
 };
 #[cfg(not(all(target_arch = "wasm32", not(feature = "webgpu"))))]
 use bevy_ui_render::prelude::MaterialNode;
@@ -32,9 +33,7 @@ use crate::frame_time_graph::FrameTimeGraphConfigUniform;
 use crate::frame_time_graph::{FrameTimeGraphPlugin, FrametimeGraphMaterial};
 
 /// [`GlobalZIndex`] used to render the fps overlay.
-///
-/// We use a number slightly under `i32::MAX` so you can render on top of it if you really need to.
-pub const FPS_OVERLAY_ZINDEX: i32 = i32::MAX - 32;
+pub const FPS_OVERLAY_ZINDEX: &str = "bevy_dev_tools::fps_overlay";
 
 // Warn the user if the interval is below this threshold.
 const MIN_SAFE_INTERVAL: Duration = Duration::from_millis(50);
@@ -67,6 +66,12 @@ pub enum FpsOverlaySystems {
 
 impl Plugin for FpsOverlayPlugin {
     fn build(&self, app: &mut bevy_app::App) {
+        app.init_resource::<GlobalZLayers>();
+        let mut layers = app.world_mut().resource_mut::<GlobalZLayers>();
+        let index = layers
+            .get_index(crate::picking_debug::DEBUG_PICKING_LAYER)
+            .map_or(layers.len(), |index| index as usize);
+        layers.insert(index, FPS_OVERLAY_ZINDEX.into());
         // TODO: Use plugin dependencies, see https://github.com/bevyengine/bevy/issues/69
         if !app.is_plugin_added::<FrameTimeDiagnosticsPlugin>() {
             app.add_plugins(FrameTimeDiagnosticsPlugin::default());
@@ -197,7 +202,7 @@ fn setup(
                 ..Default::default()
             },
             // Render overlay on top of everything
-            GlobalZIndex(FPS_OVERLAY_ZINDEX),
+            GlobalZIndex::new(FPS_OVERLAY_ZINDEX),
             Pickable::IGNORE,
         ))
         .with_children(|p| {

crates/bevy_dev_tools/src/picking_debug.rs

@@ -82,8 +82,15 @@ impl DebugPickingMode {
 #[derive(Debug, Default, Clone)]
 pub struct DebugPickingPlugin;
 
+/// [`GlobalZIndex`] used to render the picking debug overlay.
+pub const DEBUG_PICKING_LAYER: &str = "bevy_dev_tools::picking_debug";
+
 impl Plugin for DebugPickingPlugin {
     fn build(&self, app: &mut App) {
+        app.init_resource::<GlobalZLayers>();
+        app.world_mut()
+            .resource_mut::<GlobalZLayers>()
+            .push(DEBUG_PICKING_LAYER.into());
         app.register_type::<PointerDebugOverlayOf>()
             .register_type::<PointerDebugOverlay>()
             .init_resource::<DebugPickingMode>()
@@ -299,7 +306,7 @@ pub fn debug_draw(
                         ..Default::default()
                     },
                     BackgroundColor(Color::BLACK.with_alpha(0.75)),
-                    GlobalZIndex(i32::MAX),
+                    GlobalZIndex::new(DEBUG_PICKING_LAYER),
                     Pickable::IGNORE,
                     UiTargetCamera(camera),
                     children![(Text::new(text.clone()), TextFont::from_font_size(12.0))],

crates/bevy_feathers/src/controls/dialog.rs

@@ -44,6 +44,9 @@ impl Default for FeathersDialogProps {
     }
 }
 
+/// [`GlobalZIndex`] layer used by [`FeathersDialog`].
+pub const FEATHERS_DIALOG_LAYER: &str = "bevy_feathers::dialog";
+
 /// A modal dialog box
 #[derive(SceneComponent, Default, Clone, Reflect)]
 #[scene(FeathersDialogProps)]
@@ -68,7 +71,7 @@ impl FeathersDialog {
             ModalDialogBarrier
             FixedNode
             OverrideClip
-            GlobalZIndex(99) // One less than menu layer
+            GlobalZIndex::new(FEATHERS_DIALOG_LAYER) // One less than menu layer
             Children [
                 Node {
                     display: Display::Flex,

crates/bevy_feathers/src/controls/menu.rs

@@ -20,8 +20,9 @@ use bevy_reflect::Reflect;
 use bevy_scene::prelude::*;
 use bevy_text::{FontSourceTemplate, FontWeight};
 use bevy_ui::{
-    px, AlignItems, AlignSelf, BoxShadow, Display, FlexDirection, GlobalZIndex,
+    px, AlignItems, AlignSelf, BoxShadow, Display, FlexDirection, GlobalZIndex, GlobalZLayers,
     InteractionDisabled, JustifyContent, Node, OverrideClip, PositionType, Pressed, UiRect,
+    DEFAULT_GLOBAL_Z_LAYER,
 };
 use bevy_ui_widgets::{
     popover::{Popover, PopoverAlign, PopoverPlacement, PopoverSide},
@@ -339,6 +340,9 @@ impl FeathersMenuToolButton {
     }
 }
 
+/// [`GlobalZIndex`] layer used by [`FeathersMenuPopup`].
+pub const FEATHERS_MENU_LAYER: &str = "bevy_feathers::menu";
+
 /// A menu popup widget.
 #[derive(SceneComponent, Default, Clone, Reflect)]
 #[reflect(Component, Default, Clone)]
@@ -370,7 +374,7 @@ impl FeathersMenuPopup {
                 px(1),
                 px(4),
             )
-            GlobalZIndex(100)
+            GlobalZIndex::new(FEATHERS_MENU_LAYER)
             Popover {
                 positions: vec![
                     PopoverPlacement {
@@ -607,6 +611,16 @@ pub struct MenuPlugin;
 
 impl Plugin for MenuPlugin {
     fn build(&self, app: &mut bevy_app::App) {
+        app.init_resource::<GlobalZLayers>();
+        let mut layers = app.world_mut().resource_mut::<GlobalZLayers>();
+        let index = layers.get_index(DEFAULT_GLOBAL_Z_LAYER).unwrap() as usize + 1;
+        layers.splice(
+            index..index,
+            [
+                super::FEATHERS_DIALOG_LAYER.into(),
+                FEATHERS_MENU_LAYER.into(),
+            ],
+        );
         app.add_systems(
             PreUpdate,
             (

crates/bevy_feathers/src/controls/tabs.rs

@@ -27,8 +27,8 @@ use bevy_scene::prelude::*;
 use bevy_text::{FontSourceTemplate, FontWeight, LineBreak, TextLayout};
 use bevy_ui::{
     px, AlignItems, BorderRadius, BoxShadow, ComputedNode, Display, FlexDirection, GlobalZIndex,
-    InlineDirection, InteractionDisabled, Node, OuterColor, Outline, Overflow, PositionType,
-    Selected, UiRect, UiSystems, Val,
+    GlobalZLayers, InlineDirection, InteractionDisabled, Node, OuterColor, Outline, Overflow,
+    PositionType, Selected, UiRect, UiSystems, Val, DEFAULT_GLOBAL_Z_LAYER,
 };
 use bevy_ui_widgets::{
     ControlOrientation, DragOverlayRoot, DragProxy, SelectedTab, Tab, TabActivation, TabDragMode,
@@ -57,7 +57,7 @@ const STRIP_INSET: f32 = 3.0;
 const STRIP_BORDER: f32 = 1.0;
 const INDICATOR_SIZE: f32 = 2.0;
 const DRAG_PROXY_OFFSET: Vec2 = Vec2::new(10.0, 10.0);
-const DRAG_PROXY_Z: i32 = 200;
+const DRAG_PROXY_Z: &str = "bevy_feathers::tab_drag";
 
 /// A themed strip of [`FeathersTab`]s.
 ///
@@ -946,7 +946,7 @@ fn spawn_tab_drag_proxy(
             border_radius: tab_node.border_radius,
             ..Default::default()
         },
-        GlobalZIndex(DRAG_PROXY_Z),
+        GlobalZIndex::new(DRAG_PROXY_Z),
         Outline::new(
             px(1),
             px(0),
@@ -976,6 +976,14 @@ pub struct FeathersTabsPlugin;
 
 impl Plugin for FeathersTabsPlugin {
     fn build(&self, app: &mut bevy_app::App) {
+        app.init_resource::<GlobalZLayers>();
+        let mut layers = app.world_mut().resource_mut::<GlobalZLayers>();
+        let index = layers
+            .get_index(super::FEATHERS_MENU_LAYER)
+            .or_else(|_| layers.get_index(DEFAULT_GLOBAL_Z_LAYER))
+            .unwrap() as usize
+            + 1;
+        layers.insert(index, DRAG_PROXY_Z.into());
         app.add_observer(spawn_tab_drag_proxy).add_systems(
             PostUpdate,
             (

crates/bevy_ui/Cargo.toml

@@ -54,6 +54,7 @@ parley = { version = "0.11.0", default-features = false, features = ["std"] }
 swash = { version = "0.2.6" }
 tracing = { version = "0.1", default-features = false, features = ["std"] }
 
+
 [dev-dependencies]
 bevy_core_pipeline = { path = "../bevy_core_pipeline", version = "0.20.0-dev" }
 

crates/bevy_ui/src/lib.rs

@@ -150,6 +150,7 @@ impl Plugin for UiPlugin {
     fn build(&self, app: &mut App) {
         app.init_resource::<UiScale>()
             .init_resource::<UiStack>()
+            .init_resource::<GlobalZLayers>()
             .init_resource::<UiRoots>()
             .register_required_components::<
                 bevy_text::EditableText,