ecs: use generational entity ids and other optimizations

assets/scenes/load_scene_example.scn

@@ -1,30 +1,30 @@
 [
   (
-    entity: 328997855,
+    entity: 0,
     components: [
       {
-        "type": "ComponentA",
+        "type": "ComponentB",
         "map": {
-          "x": 3.0,
-          "y": 4.0,
+          "value": "hello",
         },
       },
-    ],
-  ),
-  (
-    entity: 404566393,
-    components: [
       {
         "type": "ComponentA",
         "map": {
           "x": 1.0,
           "y": 2.0,
         },
       },
+    ],
+  ),
+  (
+    entity: 1,
+    components: [
       {
-        "type": "ComponentB",
+        "type": "ComponentA",
         "map": {
-          "value": "hello",
+          "x": 3.0,
+          "y": 4.0,
         },
       },
     ],

crates/bevy_app/src/app.rs

@@ -57,7 +57,8 @@ impl App {
     }
 
     pub fn update(&mut self) {
-        self.schedule.initialize(&mut self.resources);
+        self.schedule
+            .initialize(&mut self.world, &mut self.resources);
         self.executor
             .run(&mut self.schedule, &mut self.world, &mut self.resources);
     }
@@ -69,7 +70,8 @@ impl App {
             .unwrap_or_else(DefaultTaskPoolOptions::default)
             .create_default_pools(&mut self.resources);
 
-        self.startup_schedule.initialize(&mut self.resources);
+        self.startup_schedule
+            .initialize(&mut self.world, &mut self.resources);
         self.startup_executor.run(
             &mut self.startup_schedule,
             &mut self.world,

crates/bevy_ecs/hecs/benches/bench.rs

@@ -68,7 +68,7 @@ fn iterate_100k(b: &mut Bencher) {
         world.spawn((Position(-(i as f32)), Velocity(i as f32)));
     }
     b.iter(|| {
-        for (mut pos, vel) in &mut world.query::<(&mut Position, &Velocity)>() {
+        for (mut pos, vel) in &mut world.query_mut::<(&mut Position, &Velocity)>() {
             pos.0 += vel.0;
         }
     })