Make batch management event driven (again)

src/bin/flappy/main.rs

@@ -818,33 +818,28 @@ fn manage_score(
 /// When the player moves forward while alive
 /// spawn more batches and despawn old batches
 fn hitbox_collision_handler(
-    bird: Query<&ColliderAabb, With<Bird>>,
+    mut start: EventReader<CollisionStarted>,
-    hitboxes: Query<(Entity, &ColliderAabb), With<Hitbox>>,
+    bird: Query<Entity, With<Bird>>,
-    batches: Query<(Entity, &Batch)>,
+    hitboxes: Query<(Entity, &Batch), With<Hitbox>>,
     state: Res<State<PlayerState>>,
     mut commands: Commands,
 ) {
-    bird.iter().for_each(|bird_aabb| {
+    start.read().for_each(|CollisionStarted(a, b)| {
-        if let Some(e) = hitboxes
+        // Get the current batch
-            .iter()
+        let (_, Batch(curr)) = if hitboxes.contains(*b) {
-            .find_map(|(e, hitbox_aabb)| bird_aabb.intersects(hitbox_aabb).then_some(e))
+            hitboxes.get(*b).unwrap()
-        {
+        } else { hitboxes.get(*a).unwrap() };
-            let (_, Batch(curr)) = batches.get(e).unwrap();
+
-            let (target_batch_id, new_batch_id) = match state.get() {
+        let (old_batch, new_batch) = match state.get() {
-                PlayerState::Alive => (curr.saturating_sub(2), curr.saturating_add(2)),
+            PlayerState::Alive => (curr.saturating_sub(2), curr.saturating_add(2)),
-                PlayerState::Rewind => (curr.saturating_add(2), curr.saturating_sub(2)),
+            PlayerState::Rewind => (curr.saturating_add(2), curr.saturating_sub(2)),
-                _ => (*curr, *curr),
+            _ => (*curr, *curr),
-            };
-            if target_batch_id > 0
-                && new_batch_id > 0
-                && target_batch_id != new_batch_id
-                && let Some(e_old) = batches
-                    .iter()
-                    .find_map(|(e, b)| (b.0 == target_batch_id).then_some(e))
-            {
-                commands.entity(e_old).insert(Batch(new_batch_id));
-            }
         };
+
+        let old_entity = hitboxes.iter().find_map(|(e, Batch(id))| {
+            (*id == old_batch).then_some(e)
+        }).unwrap();
+        commands.entity(old_entity).insert(Batch(new_batch));
     });
 }