make a few block, just follow the cursor if selected

src/main.rs

@@ -1,3 +1,4 @@
+use bevy::color::palettes::basic::{RED, WHITE};
 use bevy::prelude::*;
 
 mod fps_counter;
@@ -6,55 +7,114 @@ fn main() {
         .add_plugins((
             DefaultPlugins,
             fps_counter::FpsCounterPlugin,
+            MeshPickingPlugin,
         ))
+        .add_systems(Startup, setup)
+        .add_systems(Startup, change_window_mode)
+        // .add_systems(Update, switch_focused_shape)
+        .add_systems(Update, show_focused_shape)
+        .add_systems(FixedUpdate, focused_follow_cursor)
+        .add_systems(Update, draw_cursor)
         .run();
 }
-//region first app
-//region system
-fn hello_world() {
-    println!("hello world!");
-}
-//endregion
 
-//region component
-#[derive(Component)]
-struct Person;
+fn change_window_mode(mut windows: Query<&mut Window>) {
+    let mut window = windows.single_mut();
+    // window.mode = WindowMode::Fullscreen(MonitorSelection::Current);
+    window.present_mode = bevy::window::PresentMode::AutoNoVsync;
+}
+fn setup(
+    mut commands: Commands,
+    mut meshes: ResMut<Assets<Mesh>>,
+    mut materials: ResMut<Assets<ColorMaterial>>,
+) {
+    commands.spawn(Camera2d);
+
+    let shapes = [
+        meshes.add(Rectangle::new(50.0, 100.0)),
+        meshes.add(Rectangle::new(100.0, 50.0)),
+    ];
+    let num_shapes = shapes.len();
+    for (i, shape) in shapes.into_iter().enumerate() {
+        commands
+            .spawn((
+                Mesh2d(shape),
+                MeshMaterial2d(materials.add(Color::from(RED))),
+                Focused(true),
+                Transform::from_xyz((i as f32 - num_shapes as f32 / 2.0) * 150.0, 0.0, 0.0),
+            ))
+            .observe(on_click_shape);
+    }
+}
+fn draw_cursor(
+    camera_query: Single<(&Camera, &GlobalTransform)>,
+    windows: Query<&Window>,
+    mut gizmos: Gizmos,
+) {
+    let Some(point) = get_cursor_worl_pos(camera_query, windows) else {
+        return;
+    };
+
+    gizmos.circle_2d(point, 10.0, WHITE);
+}
+
+fn get_cursor_worl_pos(
+    camera_query: Single<(&Camera, &GlobalTransform)>,
+    windows: Query<&Window>,
+) -> Option<Vec2> {
+    let (camera, camera_transform) = *camera_query;
+    let Ok(window) = windows.get_single() else {
+        return None;
+    };
+    let Some(cursor_position) = window.cursor_position() else {
+        return None;
+    };
+
+    let Ok(point) = camera.viewport_to_world_2d(camera_transform, cursor_position) else {
+        return None;
+    };
+    Some(point)
+}
 
 #[derive(Component)]
-struct Name(String);
-fn add_people(mut commands: Commands) {
-    commands.spawn((Person, Name("Elaina Proctor".to_string())));
-    commands.spawn((Person, Name("Renzo Hume".to_string())));
-    commands.spawn((Person, Name("Zayna Nieves".to_string())));
-}
-#[derive(Resource)]
-struct GreetTimer(Timer);
-//endregion
-//region query
-fn greet_people(time: Res<Time>, mut timer: ResMut<GreetTimer>, query: Query<&Name, With<Person>>) {
-    if timer.0.tick(time.delta()).just_finished() {
-        for name in &query {
-            println!("hello {}!", name.0);
+struct Focused(bool);
+fn show_focused_shape(focused: Query<(&Focused, &GlobalTransform)>, mut gizmos: Gizmos) {
+    for (focused, transform) in focused.iter() {
+        let point: Vec2 = transform.translation().xy();
+        if focused.0 {
+            gizmos.circle_2d(point, 10.0, WHITE);
         }
     }
 }
-fn update_people(mut query: Query<&mut Name, With<Person>>) {
-    for mut name in &mut query {
-        if name.0 == "Elaina Proctor" {
-            name.0 = "Elaina Hume".to_string();
-            break;
+fn focused_follow_cursor(
+    time: Res<Time<Fixed>>,
+    mut focused: Query<(&Focused, &mut Transform)>,
+    camera_query: Single<(&Camera, &GlobalTransform)>,
+    windows: Query<&Window>,
+) {
+    let Some(point) = get_cursor_worl_pos(camera_query, windows) else {
+        return;
+    };
+    const MOVEMENT_SPEED: f32 = 100.0;
+    for (focused, mut transform) in focused.iter_mut() {
+        if focused.0 {
+            let move_vec = point - transform.translation.xy();
+            if move_vec.length_squared() < 0.0001 {
+                continue;
+            }
+            let capped_move_vec = move_vec.normalize() * time.delta_secs() * MOVEMENT_SPEED;
+            if capped_move_vec.length_squared() > move_vec.length_squared() {
+                transform.translation += move_vec.extend(0.0);
+                continue;
+            }
+            transform.translation += capped_move_vec.extend(0.0);
         }
     }
 }
-//endregion
-//region Plugin
-pub struct HelloPlugin;
-impl Plugin for HelloPlugin {
-    fn build(&self, app: &mut App) {
-        app.insert_resource(GreetTimer(Timer::from_seconds(2.0, TimerMode::Repeating)))
-            .add_systems(Startup, add_people)
-            .add_systems(Update, ((update_people, greet_people).chain()));
-    }
+fn on_click_shape(click: Trigger<Pointer<Click>>, mut focused: Query<&mut Focused>) {
+    let Ok(mut focused) = focused.get_mut(click.entity()) else {
+        return;
+    };
+
+    focused.0 = !focused.0;
 }
-//endregion
-//endregion