check if overload is enough before using it

src/buildings.rs

@@ -1,5 +1,6 @@
 use crate::inventory::{self};
 use crate::inventory::{Inventory, SpawnInventory};
+use crate::overload::Overload;
 use crate::random::RandomDeterministic;
 use crate::window::WindowSize;
 use crate::GameState;
@@ -48,6 +49,7 @@ pub(crate) struct GetNextBuildingParams<'w, 's> {
             &'static mut crate::inventory::Inventory<Building>,
         ),
     >,
+    q_overload: Query<'w, 's, &'static mut Overload>,
     q_buildings: Query<'w, 's, &'static Building>,
 }
 
@@ -70,9 +72,17 @@ impl BuildingInventory {
         let Ok(_item_to_build) = params.q_buildings.get(first_item) else {
             return None;
         };
+
         // TODO: check if we can build item_to_build (cooldown, space available, currency, ...)
         // TODO: send an event if not possible.
-        // TODO: pay "price" ?
+
+        let mut overload = params.q_overload.single_mut();
+        if overload.0 < 0.1 {
+            // TODO: send not enough overload event
+            return None;
+        }
+        overload.0 -= 0.1;
+
         inventory.items.pop_front();
 
         let new_building = get_random_building(&mut rng);

src/overload.rs

@@ -114,7 +114,5 @@ fn react_to_spawned_tower(
     let Ok(mut overload) = q_overload.get_single_mut() else {
         return;
     };
-    for _e in event.read() {
-        overload.0 = (overload.0 - 0.1).clamp(0.0, 1.0);
-    }
+    // TODO: particles or smth ?
 }

src/turret.rs

@@ -72,10 +72,13 @@ pub struct SpawnTurret {
 impl EntityCommand for SpawnTurret {
     fn apply(self, id: Entity, world: &mut World) {
         // TODO: attach building to the turret
-        let _building =
+        let Some(_building) =
             world.resource_scope(|world, mut building_inventory: Mut<BuildingInventory>| {
                 building_inventory.next(world)
-            });
+            })
+        else {
+            return;
+        };
 
         let texture = world.resource_scope(|_, asset_server: Mut<AssetServer>| {
             asset_server.load("textures/DifferentTurrets/Turret01.png")