Visual button interaction is working, needs act

I've taken a lot directly from the Bevy UI button example.
(https://bevy.org/examples/ui-user-interface/button/)

I'll make it look better later. For now, it just needs to exist. Onward
to the UI operation system!

src/config.rs

@@ -5,6 +5,10 @@ use bevy::color::Color;
 
 pub const WINDOW_SIZE: bevy::prelude::Vec2 = bevy::prelude::Vec2::new(800.0, 600.0);
 
+pub const UI_BUTTON_NORMAL: Color = Color::srgb(0.15, 0.15, 0.15); // Button color when it's just hanging out
+pub const UI_BUTTON_HOVERED: Color = Color::srgb(0.25, 0.25, 0.25); // ... when it's hovered
+pub const UI_BUTTON_PRESSED: Color = Color::srgb(0.35, 0.75, 0.35); // ... when it's pressed
+
 pub(crate) const BACKGROUND_COLOR: Color = Color::srgb(0.3, 0.3, 0.3);
 pub(crate) const PLAYER_SHIP_COLOR: Color = Color::srgb(1.0, 1.0, 1.0);
 pub(crate) const SHIP_THRUSTER_COLOR_ACTIVE: Color = Color::srgb(1.0, 0.2, 0.2);

src/lib.rs

@@ -13,7 +13,7 @@ mod widgets;
 use crate::config::{
     ASTEROID_SMALL_COLOR, BACKGROUND_COLOR, BULLET_COLOR, BULLET_LIFETIME, BULLET_SPEED,
     PLAYER_SHIP_COLOR, SHIP_ROTATION, SHIP_THRUST, SHIP_THRUSTER_COLOR_ACTIVE,
-    SHIP_THRUSTER_COLOR_INACTIVE, WINDOW_SIZE,
+    SHIP_THRUSTER_COLOR_INACTIVE,
 };
 use crate::machinery::AsteroidSpawner;
 use crate::objects::{Bullet, Ship};
@@ -34,8 +34,9 @@ pub struct AsteroidPlugin;
 impl Plugin for AsteroidPlugin {
     fn build(&self, app: &mut App) {
         app.add_plugins((
-            widgets::GameMenuPlugin,
-            widgets::preparation_widget_plugin,
+            widgets::PluginGameMenu,
+            widgets::PluginGameOver,
+            widgets::PluginGetReady,
             RapierPhysicsPlugin::<NoUserData>::pixels_per_meter(10.0),
             RapierDebugRenderPlugin::default(),
         ))
@@ -64,8 +65,6 @@ impl Plugin for AsteroidPlugin {
                 objects::bullet_impact_listener,
                 objects::ship_impact_listener,
                 physics::collision_listener,
-                // TODO: Remove debug printing
-                debug_collision_event_printer,
                 machinery::tick_lifetimes,
             )
                 .run_if(in_state(GameState::Playing)),
@@ -82,13 +81,7 @@ impl Plugin for AsteroidPlugin {
         .add_event::<events::AsteroidDestroy>()
         .add_event::<events::ShipDestroy>()
         .add_event::<events::BulletDestroy>();
-        app.insert_state(GameState::Playing);
-    }
-}
-
-fn debug_collision_event_printer(mut collision_events: EventReader<CollisionEvent>) {
-    for event in collision_events.read() {
-        dbg!(event);
+        app.insert_state(GameState::GameOver);
     }
 }
 

src/widgets.rs

@@ -1,34 +1,75 @@
 use crate::{
     GameState,
+    config::{UI_BUTTON_HOVERED, UI_BUTTON_NORMAL, UI_BUTTON_PRESSED},
     resources::{Lives, Score},
 };
 
 use bevy::{
-    color::palettes::css::{BLACK, GREEN, LIGHT_BLUE, RED},
+    color::palettes::css::{BLACK, GREEN, LIGHT_BLUE, RED, WHITE},
     prelude::*,
 };
 
-pub fn spawn_ui(mut commands: Commands, score: Res<Score>, lives: Res<Lives>) {
-    commands.spawn((
-        Text::new(format!("Score: {score:?} | Lives: {lives:?}")),
-        TextFont::from_font_size(25.0),
-    ));
+/// Plugin for the main menu
+pub struct PluginGameMenu;
+
+impl Plugin for PluginGameMenu {
+    fn build(&self, app: &mut App) {
+        app.add_systems(OnEnter(GameState::TitleScreen), spawn_menu)
+            .add_systems(OnExit(GameState::TitleScreen), despawn::<TitleUI>)
+            .add_systems(
+                Update,
+                handle_spacebar.run_if(in_state(GameState::TitleScreen)),
+            );
+    }
 }
 
-pub fn preparation_widget_plugin(app: &mut App) {
-    app.add_systems(OnEnter(GameState::GetReady), spawn_get_ready)
-        .add_systems(OnExit(GameState::GetReady), despawn_get_ready)
-        .add_systems(
-            Update,
-            (animate_get_ready_widget).run_if(in_state(GameState::GetReady)),
-        )
-        .insert_resource(ReadySetGoTimer(Timer::from_seconds(3.0, TimerMode::Once)));
+/// Plugin for the "get ready" period as gameplay starts.
+pub struct PluginGetReady;
+
+impl Plugin for PluginGetReady {
+    fn build(&self, app: &mut App) {
+        app.add_systems(OnEnter(GameState::GetReady), spawn_get_ready)
+            .add_systems(OnExit(GameState::GetReady), despawn::<OnReadySetGo>)
+            .add_systems(
+                Update,
+                (animate_get_ready_widget).run_if(in_state(GameState::GetReady)),
+            )
+            .insert_resource(ReadySetGoTimer(Timer::from_seconds(3.0, TimerMode::Once)));
+    }
+}
+
+/// Plugin for the game-over screen (TODO)
+pub struct PluginGameOver;
+
+impl Plugin for PluginGameOver {
+    fn build(&self, app: &mut App) {
+        app.add_systems(OnEnter(GameState::GameOver), spawn_gameover_ui)
+            .add_systems(OnExit(GameState::GameOver), despawn::<MarkerGameOver>)
+            .add_systems(
+                Update,
+                operate_gameover_ui.run_if(in_state(GameState::GameOver)),
+            );
+    }
 }
 
 /// Marker component for things on the get-ready indicator
 #[derive(Component)]
 struct OnReadySetGo;
 
+/// Marker for things on the game-over screen
+#[derive(Component)]
+struct MarkerGameOver;
+
+/// Action specifier for the game-over menu's buttons.
+///
+/// Attach this component to a button and [`PluginGameOver`] will use it to
+/// decide what to do when that button is pressed.
+#[derive(Component)]
+enum GameOverMenuAction {
+    ToMainMenu,
+    Quit,
+}
+
 /// Newtype wrapper for `Timer`. Used to count down during the "get ready" phase.
 #[derive(Deref, DerefMut, Resource)]
 struct ReadySetGoTimer(Timer);
@@ -41,6 +82,14 @@ struct CountdownText;
 #[derive(Component)]
 struct CountdownBar;
 
+/// Despawns entities matching the generic argument. Intended to remove UI
+/// elements.
+fn despawn<T: Component>(mut commands: Commands, to_despawn: Query<Entity, With<T>>) {
+    for entity in to_despawn {
+        commands.entity(entity).despawn();
+    }
+}
+
 fn spawn_get_ready(mut commands: Commands) {
     commands.spawn((
         OnReadySetGo, // marker, so this can be de-spawned properly
@@ -75,12 +124,63 @@ fn spawn_get_ready(mut commands: Commands) {
     ));
 }
 
-// TODO: Replace this with a generic somewhere else in the crate
-// want: `despawn_screen::<OnReadySetGo>>()`
-fn despawn_get_ready(mut commands: Commands, to_despawn: Query<Entity, With<OnReadySetGo>>) {
-    for entity in to_despawn {
-        commands.entity(entity).despawn();
-    }
+/// Spawns the game over screen.
+///
+/// Used by [`PluginGameOver`] when entering the [`GameState::GameOver`] state.
+fn spawn_gameover_ui(mut commands: Commands) {
+    commands.spawn((
+        MarkerGameOver, // Marker, so `despawn<T>` can remove this on state exit.
+        Node {
+            width: Val::Percent(100.0),
+            height: Val::Percent(100.0),
+            align_items: AlignItems::Center,
+            justify_content: JustifyContent::Center,
+            flex_direction: FlexDirection::Column,
+            ..default()
+        },
+        children![
+            (
+                Button,
+                Node {
+                    width: Val::Px(150.0),
+                    height: Val::Px(65.0),
+                    border: UiRect::all(Val::Px(2.0)),
+                    justify_content: JustifyContent::Center,
+                    align_items: AlignItems::Center,
+                    margin: UiRect::all(Val::Px(5.0)),
+                    ..default()
+                },
+                BorderColor(Color::BLACK),
+                BorderRadius::MAX,
+                BackgroundColor(UI_BUTTON_NORMAL),
+                children![(
+                    Text::new("Main Menu"),
+                    TextColor(Color::srgb(0.9, 0.9, 0.9)),
+                    TextShadow::default(),
+                )]
+            ),
+            (
+                Button,
+                Node {
+                    width: Val::Px(150.0),
+                    height: Val::Px(65.0),
+                    border: UiRect::all(Val::Px(2.0)),
+                    justify_content: JustifyContent::Center,
+                    align_items: AlignItems::Center,
+                    margin: UiRect::all(Val::Px(5.0)),
+                    ..default()
+                },
+                BorderColor(Color::BLACK),
+                BorderRadius::MAX,
+                BackgroundColor(UI_BUTTON_NORMAL),
+                children![(
+                    Text::new("Quit"),
+                    TextColor(Color::srgb(0.9, 0.9, 0.9)),
+                    TextShadow::default(),
+                )]
+            )
+        ],
+    ));
 }
 
 fn animate_get_ready_widget(
@@ -108,16 +208,35 @@ fn animate_get_ready_widget(
     }
 }
 
-pub struct GameMenuPlugin;
-
-impl Plugin for GameMenuPlugin {
-    fn build(&self, app: &mut App) {
-        app.add_systems(OnEnter(GameState::TitleScreen), spawn_menu)
-            .add_systems(OnExit(GameState::TitleScreen), despawn_menu)
-            .add_systems(
-                Update,
-                handle_spacebar.run_if(in_state(GameState::TitleScreen)),
-            );
+/// Handles interaction and performs updates to the game-over UI.
+///
+/// Used by [`PluginGameOver`] while in the [`GameState::GameOver`] state.
+///
+/// Mostly a button input handler, but it also makes for a convenient single
+/// place to keep all system logic for this plugin.
+fn operate_gameover_ui(
+    mut interactions: Query<
+        (&Interaction, &mut BackgroundColor, &mut BorderColor),
+        (Changed<Interaction>, With<Button>),
+    >,
+) {
+    // TODO: Better colors. These are taken from the example and they're ugly.
+    // TODO: Read the menu action enum component and take that action.
+    for (interaction, mut color, mut border_color) in &mut interactions {
+        match *interaction {
+            Interaction::Pressed => {
+                *color = UI_BUTTON_PRESSED.into();
+                border_color.0 = RED.into();
+            }
+            Interaction::Hovered => {
+                *color = UI_BUTTON_HOVERED.into();
+                border_color.0 = WHITE.into();
+            }
+            Interaction::None => {
+                *color = UI_BUTTON_NORMAL.into();
+                border_color.0 = BLACK.into();
+            }
+        }
     }
 }
 
@@ -147,14 +266,15 @@ fn spawn_menu(mut commands: Commands) {
         });
 }
 
-fn despawn_menu(mut commands: Commands, to_despawn: Query<Entity, With<TitleUI>>) {
-    for entity in &to_despawn {
-        commands.entity(entity).despawn();
-    }
-}
-
 fn handle_spacebar(input: Res<ButtonInput<KeyCode>>, mut game_state: ResMut<NextState<GameState>>) {
     if input.just_pressed(KeyCode::Space) {
         game_state.set(GameState::GetReady);
     }
 }
+
+pub fn spawn_ui(mut commands: Commands, score: Res<Score>, lives: Res<Lives>) {
+    commands.spawn((
+        Text::new(format!("Score: {score:?} | Lives: {lives:?}")),
+        TextFont::from_font_size(25.0),
+    ));
+}