Replace base-ui bundle with a spawning function

src/main.rs

@@ -1,7 +1,7 @@
 use bevy::{prelude::*, window::WindowResolution};
 use bevy_inspector_egui::{bevy_egui::EguiPlugin, quick::WorldInspectorPlugin};
 
-use crate::game::machines::RotatingMachine;
+use crate::game::machines::{CuttingMachine, RotatingMachine};
 
 mod assets;
 mod card;
@@ -24,7 +24,12 @@ fn main() {
     .register_type::<resources::UiTheme>()
     .add_systems(
       Startup,
-      (setup, assets::load_assets, RotatingMachine::spawn_ui),
+      (
+        setup,
+        assets::load_assets,
+        RotatingMachine::spawn_ui,
+        CuttingMachine::spawn_ui,
+      ),
     )
     .add_observer(widgets::CloseButton::hover_start)
     .add_observer(widgets::CloseButton::hover_stop)

src/resources.rs

@@ -1,11 +1,16 @@
 //! Program constants & defaults
 
-use bevy::{color::palettes::css::*, prelude::*};
+use bevy::{
+  color::palettes::{css::*, tailwind::SLATE_100},
+  prelude::*,
+};
 
 #[derive(Debug, Reflect, Resource)]
 #[reflect(Resource)]
 pub struct UiTheme {
-  // TODO: Panes
+  // Colors for the machine UI panes
+  // (and others, but we're not there yet)
+  pub pane_bg: Color,
 
   // Colors for the "Big Red Buttons" (the main actions of the machines)
   // normal
@@ -33,6 +38,8 @@ pub struct UiTheme {
 impl FromWorld for UiTheme {
   fn from_world(world: &mut World) -> Self {
     Self {
+      pane_bg: SLATE_100.into(),
+
       brb_bg: RED.into(),
       brb_border: DARK_RED.into(),
       brb_hover_bg: PINK.into(),

src/widgets/machines.rs

@@ -2,14 +2,14 @@ use bevy::{color::palettes::css::*, prelude::*, ui::Val::*};
 
 use crate::{
   game::machines::*,
-  widgets::{CloseButton, machine_ui_base, spawn_big_red_button},
+  resources::UiTheme,
+  widgets::{machine_ui_base, spawn_big_red_button},
 };
 
 impl CuttingMachine {
-  pub fn spawn_ui(mut commands: Commands) {
-    commands
-      .spawn((machine_ui_base("Cutting Machine"),))
-      .with_children(|commands| {
+  pub fn spawn_ui(mut commands: Commands, theme: Res<UiTheme>) {
+    let base_entity = machine_ui_base(&mut commands, "Cutting Machine", &theme);
+    commands.entity(base_entity).with_children(|commands| {
       // Left panel. For fuel or machine stats or whatever.
       commands.spawn((
         Node {
@@ -48,11 +48,9 @@ impl CuttingMachine {
 }
 
 impl RotatingMachine {
-  pub fn spawn_ui(mut commands: Commands) {
-    commands
-      .spawn((machine_ui_base("Rotating Machine"),))
-      .with_children(|commands| {
-        commands.spawn(CloseButton::bundle(commands.target_entity()));
+  pub fn spawn_ui(mut commands: Commands, theme: Res<UiTheme>) {
+    let base_entity = machine_ui_base(&mut commands, "Rotating Machine", &theme);
+    commands.entity(base_entity).with_children(|commands| {
       commands.spawn((
         Node {
           padding: UiRect::all(Px(10.0)),

src/widgets/mod.rs

@@ -2,17 +2,19 @@
 
 pub mod machines;
 
-use bevy::{
-  color::palettes::{css::*, tailwind::*},
-  prelude::*,
-  ui::Val::*,
-};
+use bevy::{color::palettes::css::*, prelude::*, ui::Val::*};
 
 use crate::resources::UiTheme;
 
 /// The base panel for the machines that manipulate the room cards.
-fn machine_ui_base(header: impl Into<String>) -> impl Bundle {
-  (
+///
+/// This function is not a valid Bevy System because of how the Commands struct
+/// is passed through. Users are meant to call this *from* a System to create a
+/// base UI Node. That system then re-acquires an [`EntityCommands`] and adds
+/// child nodes to fill out the panel.
+fn machine_ui_base(commands: &mut Commands, header: impl Into<String>, theme: &UiTheme) -> Entity {
+  let root_pane = commands
+    .spawn((
       Node {
         // Position & size
         position_type: PositionType::Relative,
@@ -36,7 +38,7 @@ fn machine_ui_base(header: impl Into<String>) -> impl Bundle {
 
         ..default()
       },
-    BackgroundColor(SLATE_100.into()),
+      BackgroundColor(theme.pane_bg),
       BorderRadius::all(Percent(2.0)),
       children![(
         // TODO: A real node with stuff in it (buttons, maybe?)
@@ -53,7 +55,13 @@ fn machine_ui_base(header: impl Into<String>) -> impl Bundle {
           // TODO: Text shadow, maybe. I couldn't make it look good.
         )],
       ),],
-  )
+    ))
+    .id();
+
+  commands.entity(root_pane).with_children(|cmds| {
+    cmds.spawn(CloseButton::bundle(root_pane));
+  });
+  root_pane
 }
 
 // TODO: Hook up action handling (callback? Observer? Some other weird component?)