she moves!

src/main.rs

@@ -14,25 +14,32 @@ fn main() {
         .init_resource::<BoidMesh>()
         .add_plugins(DefaultPlugins)
         .add_systems(Startup, (build_boid_mesh, setup).chain())
+        .add_systems(Update, move_boids)
         .run();
 }
 
 #[derive(Resource, Default)]
 struct BoidMesh(Mesh2dHandle);
 
-#[derive(Component)]
+#[derive(Component, Default)]
 struct Boid;
 
-#[derive(Component)]
-struct Velocity(Vec2);
+#[derive(Component, Default)]
+struct Velocity(Vec3);
 
-#[derive(Bundle)]
+#[derive(Bundle, Default)]
 struct BoidBundle {
     mesh: MaterialMesh2dBundle<ColorMaterial>,
     velocity: Velocity,
     boid: Boid,
 }
 
+fn move_boids(mut boids: Query<(&mut Transform, &Velocity), With<Boid>>) {
+    boids.iter_mut().for_each(|(mut transform, velocity)| {
+        transform.translation += velocity.0;
+    });
+}
+
 fn build_boid_mesh(mut meshes: ResMut<Assets<Mesh>>, mut boid_mesh: ResMut<BoidMesh>) {
     let mesh = Mesh2dHandle(meshes.add(make_boid_mesh()));
     boid_mesh.0 = mesh;
@@ -47,10 +54,14 @@ fn setup(
 
     let boid_color = materials.add(Color::from(tailwind::NEUTRAL_50));
 
-    commands.spawn(MaterialMesh2dBundle {
-        mesh: boid_mesh.0.clone(),
-        material: boid_color,
-        transform: Transform::from_scale(Vec3::splat(2.5)),
+    commands.spawn(BoidBundle {
+        mesh: MaterialMesh2dBundle {
+            mesh: boid_mesh.0.clone(),
+            material: boid_color,
+            transform: Transform::from_scale(Vec3::splat(2.5)),
+            ..default()
+        },
+        velocity: Velocity(Vec3::Y),
         ..default()
     });
 }