add setup resources

crates/bevy_app/src/app.rs

@@ -11,7 +11,10 @@ use bevy_ecs::{
     system::Resource,
     world::World,
 };
-use bevy_utils::{tracing::debug, HashMap};
+use bevy_utils::{
+    tracing::{debug, error},
+    HashMap,
+};
 use std::fmt::Debug;
 
 #[cfg(feature = "trace")]
@@ -28,6 +31,10 @@ bevy_utils::define_label!(
 #[derive(Resource, Clone, Deref, DerefMut, Default)]
 pub struct AppTypeRegistry(pub bevy_reflect::TypeRegistryArc);
 
+/// Wrapper struct for setting setup resources aside
+#[derive(Resource)]
+struct Setup<T>(T);
+
 #[allow(clippy::needless_doctest_main)]
 /// A container of app logic and data.
 ///
@@ -68,6 +75,7 @@ pub struct App {
     /// A container of [`Stage`]s set to be run in a linear order.
     pub schedule: Schedule,
     sub_apps: HashMap<AppLabelId, SubApp>,
+    setup_resources: HashMap<std::any::TypeId, &'static str>,
 }
 
 /// Each `SubApp` has its own [`Schedule`] and [`World`], enabling a separation of concerns.
@@ -111,6 +119,7 @@ impl App {
             schedule: Default::default(),
             runner: Box::new(run_once),
             sub_apps: HashMap::default(),
+            setup_resources: Default::default(),
         }
     }
 
@@ -136,6 +145,8 @@ impl App {
         #[cfg(feature = "trace")]
         let _bevy_app_run_span = info_span!("bevy_app").entered();
 
+        self.check_all_setup_resources_consumed();
+
         let mut app = std::mem::replace(self, App::empty());
         let runner = std::mem::replace(&mut app.runner, Box::new(run_once));
         (runner)(app);
@@ -654,6 +665,44 @@ impl App {
         self
     }
 
+    /// Inserts a setup resource to the current [App] and overwrites any resource
+    /// previously added of the same type.
+    ///
+    /// A setup resource is used at startup for plugin initialisation and configuration.
+    /// All setup resources inserted must be consumed by a plugin and removed before the
+    /// application is ran.
+    pub fn insert_setup_resource<T>(&mut self, resource: T) -> &mut Self
+    where
+        T: Resource,
+    {
+        self.setup_resources
+            .insert(std::any::TypeId::of::<T>(), std::any::type_name::<T>());
+        self.insert_resource(Setup(resource));
+        self
+    }
+
+    /// Consumes a setup resource, and removes it from the current [App] so that a plugin
+    /// can use it for its setup.
+    pub fn consume_setup_resource<T>(&mut self) -> Option<T>
+    where
+        T: Resource,
+    {
+        self.setup_resources.remove(&std::any::TypeId::of::<T>());
+        self.world
+            .remove_resource::<Setup<T>>()
+            .map(|setup| setup.0)
+    }
+
+    /// Check that all setup resources have been consumed, panicking otherwise.
+    fn check_all_setup_resources_consumed(&self) {
+        self.setup_resources
+            .values()
+            .for_each(|v| error!("Setup resource \"{}\" has not been consumed", v));
+        if !self.setup_resources.is_empty() {
+            panic!("Not all setup resources have been consumed. This can happen if you inserted a setup resource after the plugin consuming it.")
+        }
+    }
+
     /// Inserts a [`Resource`] to the current [`App`] and overwrites any [`Resource`] previously added of the same type.
     ///
     /// A [`Resource`] in Bevy represents globally unique data. [`Resource`]s must be added to Bevy apps

crates/bevy_asset/src/debug_asset_server.rs

@@ -76,7 +76,7 @@ impl Plugin for DebugAssetServerPlugin {
         });
         let mut debug_asset_app = App::new();
         debug_asset_app
-            .insert_resource(AssetServerSettings {
+            .insert_setup_resource(AssetServerSettings {
                 asset_folder: "crates".to_string(),
                 watch_for_changes: true,
             })

crates/bevy_asset/src/lib.rs

@@ -91,8 +91,8 @@ impl Default for AssetServerSettings {
 /// delegate to the default `AssetIo` for the platform.
 pub fn create_platform_default_asset_io(app: &mut App) -> Box<dyn AssetIo> {
     let settings = app
-        .world
-        .get_resource_or_insert_with(AssetServerSettings::default);
+        .consume_setup_resource::<AssetServerSettings>()
+        .unwrap_or_default();
 
     #[cfg(all(not(target_arch = "wasm32"), not(target_os = "android")))]
     let source = FileAssetIo::new(&settings.asset_folder, settings.watch_for_changes);

crates/bevy_core/src/lib.rs

@@ -27,9 +27,7 @@ pub struct CorePlugin;
 impl Plugin for CorePlugin {
     fn build(&self, app: &mut App) {
         // Setup the default bevy task pools
-        app.world
-            .get_resource::<DefaultTaskPoolOptions>()
-            .cloned()
+        app.consume_setup_resource::<DefaultTaskPoolOptions>()
             .unwrap_or_default()
             .create_default_pools();
 

crates/bevy_log/src/lib.rs

@@ -47,14 +47,14 @@ use tracing_subscriber::{prelude::*, registry::Registry, EnvFilter};
 /// * Using [`tracing-wasm`](https://crates.io/crates/tracing-wasm) in WASM, logging
 /// to the browser console.
 ///
-/// You can configure this plugin using the resource [`LogSettings`].
+/// You can configure this plugin using the setup resource [`LogSettings`].
 /// ```no_run
 /// # use bevy_app::{App, NoopPluginGroup as DefaultPlugins};
 /// # use bevy_log::LogSettings;
 /// # use bevy_utils::tracing::Level;
 /// fn main() {
 ///     App::new()
-///         .insert_resource(LogSettings {
+///         .insert_setup_resource(LogSettings {
 ///             level: Level::DEBUG,
 ///             filter: "wgpu=error,bevy_render=info,bevy_ecs=trace".to_string(),
 ///         })
@@ -122,7 +122,9 @@ impl Plugin for LogPlugin {
         }
 
         let default_filter = {
-            let settings = app.world.get_resource_or_insert_with(LogSettings::default);
+            let settings = app
+                .consume_setup_resource::<LogSettings>()
+                .unwrap_or_default();
             format!("{},{}", settings.level, settings.filter)
         };
         LogTracer::init().unwrap();

crates/bevy_window/src/event.rs

@@ -1,6 +1,6 @@
 use std::path::PathBuf;
 
-use super::{WindowDescriptor, WindowId};
+use super::{WindowId, WindowSetupDescriptor};
 use bevy_math::{IVec2, Vec2};
 
 /// A window event that is sent whenever a window's logical size has changed.
@@ -17,7 +17,7 @@ pub struct WindowResized {
 #[derive(Debug, Clone)]
 pub struct CreateWindow {
     pub id: WindowId,
-    pub descriptor: WindowDescriptor,
+    pub descriptor: WindowSetupDescriptor,
 }
 
 /// An event that indicates the window should redraw, even if its control flow is set to `Wait` and

crates/bevy_window/src/lib.rs

@@ -17,7 +17,7 @@ pub mod prelude {
     #[doc(hidden)]
     pub use crate::{
         CursorEntered, CursorIcon, CursorLeft, CursorMoved, FileDragAndDrop, MonitorSelection,
-        ReceivedCharacter, Window, WindowDescriptor, WindowMode, WindowMoved, WindowPosition,
+        ReceivedCharacter, Window, WindowMode, WindowMoved, WindowPosition, WindowSetupDescriptor,
         Windows,
     };
 }
@@ -99,9 +99,7 @@ impl Plugin for WindowPlugin {
 
         if settings.add_primary_window {
             let window_descriptor = app
-                .world
-                .get_resource::<WindowDescriptor>()
-                .cloned()
+                .consume_setup_resource::<WindowSetupDescriptor>()
                 .unwrap_or_default();
             let mut create_window_event = app.world.resource_mut::<Events<CreateWindow>>();
             create_window_event.send(CreateWindow {

crates/bevy_window/src/window.rs

@@ -20,8 +20,9 @@ pub struct WindowId(Uuid);
 ///
 /// `Immediate` or `Mailbox` will gracefully fallback to `Fifo` when unavailable.
 ///
-/// The presentation mode may be declared in the [`WindowDescriptor`](WindowDescriptor::present_mode)
-/// or updated on a [`Window`](Window::set_present_mode).
+/// The presentation mode may be declared in the
+/// [`WindowSetupDescriptor`](WindowSetupDescriptor::present_mode) or updated on a
+/// [`Window`](Window::set_present_mode).
 #[repr(C)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 #[doc(alias = "vsync")]
@@ -305,7 +306,7 @@ impl Window {
     /// Creates a new [`Window`].
     pub fn new(
         id: WindowId,
-        window_descriptor: &WindowDescriptor,
+        window_descriptor: &WindowSetupDescriptor,
         physical_width: u32,
         physical_height: u32,
         scale_factor: f64,
@@ -751,13 +752,13 @@ pub enum WindowPosition {
     Automatic,
     /// Center the window on the monitor.
     ///
-    /// The monitor to center the window on can be selected with the `monitor` field in `WindowDescriptor`.
+    /// The monitor to center the window on can be selected with the `monitor` field in `WindowSetupDescriptor`.
     Centered,
     /// The window's top-left corner will be placed at the specified position in pixels.
     ///
     /// (0,0) represents top-left corner of the monitor.
     ///
-    /// The monitor to position the window on can be selected with the `monitor` field in `WindowDescriptor`.
+    /// The monitor to position the window on can be selected with the `monitor` field in `WindowSetupDescriptor`.
     At(Vec2),
 }
 
@@ -783,7 +784,7 @@ pub enum MonitorSelection {
 ///
 /// [`examples/window/window_settings.rs`]: https://github.com/bevyengine/bevy/blob/latest/examples/window/window_settings.rs
 #[derive(Resource, Debug, Clone)]
-pub struct WindowDescriptor {
+pub struct WindowSetupDescriptor {
     /// The requested logical width of the window's client area.
     ///
     /// May vary from the physical width due to different pixel density on different monitors.
@@ -861,9 +862,9 @@ pub struct WindowDescriptor {
     pub fit_canvas_to_parent: bool,
 }
 
-impl Default for WindowDescriptor {
+impl Default for WindowSetupDescriptor {
     fn default() -> Self {
-        WindowDescriptor {
+        WindowSetupDescriptor {
             title: "app".to_string(),
             width: 1280.,
             height: 720.,

crates/bevy_winit/src/winit_windows.rs

@@ -1,6 +1,6 @@
 use bevy_math::{DVec2, IVec2};
 use bevy_utils::HashMap;
-use bevy_window::{MonitorSelection, Window, WindowDescriptor, WindowId, WindowMode};
+use bevy_window::{MonitorSelection, Window, WindowId, WindowMode, WindowSetupDescriptor};
 use raw_window_handle::HasRawWindowHandle;
 use winit::{
     dpi::{LogicalPosition, LogicalSize, PhysicalPosition, PhysicalSize},
@@ -23,11 +23,11 @@ impl WinitWindows {
         &mut self,
         event_loop: &winit::event_loop::EventLoopWindowTarget<()>,
         window_id: WindowId,
-        window_descriptor: &WindowDescriptor,
+        window_descriptor: &WindowSetupDescriptor,
     ) -> Window {
         let mut winit_window_builder = winit::window::WindowBuilder::new();
 
-        let &WindowDescriptor {
+        let &WindowSetupDescriptor {
             width,
             height,
             position,

examples/app/logs.rs

@@ -5,7 +5,7 @@ use bevy::prelude::*;
 fn main() {
     App::new()
         // Uncomment this to override the default log settings:
-        // .insert_resource(bevy::log::LogSettings {
+        // .insert_setup_resource(bevy::log::LogSettings {
         //     level: bevy::log::Level::TRACE,
         //     filter: "wgpu=warn,bevy_ecs=info".to_string(),
         // })
@@ -24,7 +24,7 @@ fn log_system() {
     error!("something failed");
 
     // by default, trace and debug logs are ignored because they are "noisy"
-    // you can control what level is logged by adding the LogSettings resource
+    // you can control what level is logged by adding the LogSettings setup resource
     // alternatively you can set the log level via the RUST_LOG=LEVEL environment variable
     // ex: RUST_LOG=trace, RUST_LOG=info,bevy_ecs=warn
     // the format used here is super flexible. check out this documentation for more info:

examples/app/thread_pool_resources.rs

@@ -5,7 +5,7 @@ use bevy::prelude::*;
 
 fn main() {
     App::new()
-        .insert_resource(DefaultTaskPoolOptions::with_num_threads(4))
+        .insert_setup_resource(DefaultTaskPoolOptions::with_num_threads(4))
         .add_plugins(DefaultPlugins)
         .run();
 }

examples/asset/hot_asset_reloading.rs

@@ -7,7 +7,7 @@ use bevy::{asset::AssetServerSettings, prelude::*};
 fn main() {
     App::new()
         // Tell the asset server to watch for asset changes on disk:
-        .insert_resource(AssetServerSettings {
+        .insert_setup_resource(AssetServerSettings {
             watch_for_changes: true,
             ..default()
         })

examples/ios/src/lib.rs

@@ -4,7 +4,7 @@ use bevy::{input::touch::TouchPhase, prelude::*, window::WindowMode};
 #[bevy_main]
 fn main() {
     App::new()
-        .insert_resource(WindowDescriptor {
+        .insert_setup_resource(WindowSetupDescriptor {
             resizable: false,
             mode: WindowMode::BorderlessFullscreen,
             ..default()

examples/shader/compute_shader_game_of_life.rs

@@ -13,7 +13,7 @@ use bevy::{
         renderer::{RenderContext, RenderDevice},
         RenderApp, RenderStage,
     },
-    window::WindowDescriptor,
+    window::WindowSetupDescriptor,
 };
 use std::borrow::Cow;
 
@@ -23,7 +23,7 @@ const WORKGROUP_SIZE: u32 = 8;
 fn main() {
     App::new()
         .insert_resource(ClearColor(Color::BLACK))
-        .insert_resource(WindowDescriptor {
+        .insert_setup_resource(WindowSetupDescriptor {
             // uncomment for unthrottled FPS
             // present_mode: bevy::window::PresentMode::AutoNoVsync,
             ..default()

examples/stress_tests/bevymark.rs

@@ -29,7 +29,7 @@ struct Bird {
 
 fn main() {
     App::new()
-        .insert_resource(WindowDescriptor {
+        .insert_setup_resource(WindowSetupDescriptor {
             title: "BevyMark".to_string(),
             width: 800.,
             height: 600.,

examples/stress_tests/many_buttons.rs

@@ -11,7 +11,7 @@ const FONT_SIZE: f32 = 7.0;
 /// This example shows what happens when there is a lot of buttons on screen.
 fn main() {
     App::new()
-        .insert_resource(WindowDescriptor {
+        .insert_setup_resource(WindowSetupDescriptor {
             present_mode: PresentMode::Immediate,
             ..default()
         })

examples/stress_tests/many_cubes.rs

@@ -21,7 +21,7 @@ use bevy::{
 
 fn main() {
     App::new()
-        .insert_resource(WindowDescriptor {
+        .insert_setup_resource(WindowSetupDescriptor {
             present_mode: PresentMode::AutoNoVsync,
             ..default()
         })

examples/stress_tests/many_foxes.rs

@@ -18,7 +18,7 @@ struct Foxes {
 
 fn main() {
     App::new()
-        .insert_resource(WindowDescriptor {
+        .insert_setup_resource(WindowSetupDescriptor {
             title: "🦊🦊🦊 Many Foxes! 🦊🦊🦊".to_string(),
             present_mode: PresentMode::AutoNoVsync,
             ..default()

examples/stress_tests/many_lights.rs

@@ -15,7 +15,7 @@ use rand::{thread_rng, Rng};
 
 fn main() {
     App::new()
-        .insert_resource(WindowDescriptor {
+        .insert_setup_resource(WindowSetupDescriptor {
             width: 1024.0,
             height: 768.0,
             title: "many_lights".to_string(),

examples/stress_tests/many_sprites.rs

@@ -24,7 +24,7 @@ struct ColorTint(bool);
 
 fn main() {
     App::new()
-        .insert_resource(WindowDescriptor {
+        .insert_setup_resource(WindowSetupDescriptor {
             present_mode: PresentMode::AutoNoVsync,
             ..default()
         })

examples/tools/scene_viewer.rs

@@ -45,11 +45,11 @@ Controls:
         color: Color::WHITE,
         brightness: 1.0 / 5.0f32,
     })
-    .insert_resource(AssetServerSettings {
+    .insert_setup_resource(AssetServerSettings {
         asset_folder: std::env::var("CARGO_MANIFEST_DIR").unwrap_or_else(|_| ".".to_string()),
         watch_for_changes: true,
     })
-    .insert_resource(WindowDescriptor {
+    .insert_setup_resource(WindowSetupDescriptor {
         title: "bevy scene viewer".to_string(),
         ..default()
     })