Remove add_default_plugins and add MinimalPlugins for simple "headles…

…s" scenarios (#767)

Remove add_default_plugins and add MinimalPlugins for simple "headless" scenarios

crates/bevy_app/src/schedule_runner.rs

@@ -29,36 +29,42 @@ impl Default for RunMode {
     }
 }
 
-/// Configures an App to run its [Schedule](bevy_ecs::Schedule) according to a given [RunMode]
-#[derive(Default)]
-pub struct ScheduleRunnerPlugin {
+#[derive(Copy, Clone, Default)]
+pub struct ScheduleRunnerSettings {
     pub run_mode: RunMode,
 }
 
-impl ScheduleRunnerPlugin {
+impl ScheduleRunnerSettings {
     pub fn run_once() -> Self {
-        ScheduleRunnerPlugin {
+        ScheduleRunnerSettings {
             run_mode: RunMode::Once,
         }
     }
 
     pub fn run_loop(wait_duration: Duration) -> Self {
-        ScheduleRunnerPlugin {
+        ScheduleRunnerSettings {
             run_mode: RunMode::Loop {
                 wait: Some(wait_duration),
             },
         }
     }
 }
 
+/// Configures an App to run its [Schedule](bevy_ecs::Schedule) according to a given [RunMode]
+#[derive(Default)]
+pub struct ScheduleRunnerPlugin {}
+
 impl Plugin for ScheduleRunnerPlugin {
     fn build(&self, app: &mut AppBuilder) {
-        let run_mode = self.run_mode;
+        let settings = app
+            .resources_mut()
+            .get_or_insert_with(ScheduleRunnerSettings::default)
+            .to_owned();
         app.set_runner(move |mut app: App| {
             app.initialize();
 
             let mut app_exit_event_reader = EventReader::<AppExit>::default();
-            match run_mode {
+            match settings.run_mode {
                 RunMode::Once => {
                     app.update();
                 }

examples/2d/sprite.rs

@@ -2,7 +2,7 @@ use bevy::prelude::*;
 
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_startup_system(setup.system())
         .run();
 }

examples/2d/sprite_sheet.rs

@@ -2,7 +2,7 @@ use bevy::prelude::*;
 
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_startup_system(setup.system())
         .add_system(animate_sprite_system.system())
         .run();

examples/2d/texture_atlas.rs

@@ -4,7 +4,7 @@ use bevy::{asset::LoadState, prelude::*, sprite::TextureAtlasBuilder};
 fn main() {
     App::build()
         .init_resource::<RpgSpriteHandles>()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_startup_system(setup.system())
         .add_system(load_atlas.system())
         .run();

examples/3d/3d_scene.rs

@@ -3,7 +3,7 @@ use bevy::prelude::*;
 fn main() {
     App::build()
         .add_resource(Msaa { samples: 4 })
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_startup_system(setup.system())
         .run();
 }

examples/3d/load_gltf.rs

@@ -3,7 +3,7 @@ use bevy::prelude::*;
 fn main() {
     App::build()
         .add_resource(Msaa { samples: 4 })
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_startup_system(setup.system())
         .run();
 }

examples/3d/msaa.rs

@@ -6,7 +6,7 @@ use bevy::prelude::*;
 fn main() {
     App::build()
         .add_resource(Msaa { samples: 4 })
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_startup_system(setup.system())
         .run();
 }

examples/3d/parenting.rs

@@ -5,7 +5,7 @@ use bevy::prelude::*;
 fn main() {
     App::build()
         .add_resource(Msaa { samples: 4 })
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_startup_system(setup.system())
         .add_system(rotator_system.system())
         .run();

examples/3d/spawner.rs

@@ -10,7 +10,7 @@ use rand::{rngs::StdRng, Rng, SeedableRng};
 /// NOTE: Bevy still has a number of optimizations to do in this area. Expect the performance here to go way up in the future
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_plugin(FrameTimeDiagnosticsPlugin::default())
         .add_plugin(PrintDiagnosticsPlugin::default())
         .add_startup_system(setup.system())

examples/3d/texture.rs

@@ -3,7 +3,7 @@ use bevy::prelude::*;
 /// This example shows various ways to configure texture materials in 3D
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_startup_system(setup.system())
         .run();
 }

examples/3d/z_sort_debug.rs

@@ -9,7 +9,7 @@ use bevy::{
 /// This example visualizes camera z-ordering by setting the material of rotating cubes to their distance from the camera
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_startup_system(setup.system())
         .add_system(rotator_system.system())
         .add_system(camera_order_color_system.system())

examples/app/empty_defaults.rs

@@ -1,5 +1,5 @@
 use bevy::prelude::*;
 
 fn main() {
-    App::build().add_default_plugins().run();
+    App::build().add_plugin_group(DefaultPlugins).run();
 }

examples/app/headless.rs

@@ -1,7 +1,7 @@
-use bevy::{app::ScheduleRunnerPlugin, prelude::*};
+use bevy::{app::ScheduleRunnerSettings, prelude::*};
 use std::time::Duration;
 
-// This example disables the default plugins by not registering them during setup.
+// This example only enables a minimal set of plugins required for bevy to run.
 // You can also completely remove rendering / windowing Plugin code from bevy
 // by making your import look like this in your Cargo.toml
 //
@@ -12,15 +12,17 @@ use std::time::Duration;
 fn main() {
     // this app runs once
     App::build()
-        .add_plugin(ScheduleRunnerPlugin::run_once())
+        .add_resource(ScheduleRunnerSettings::run_once())
+        .add_plugin_group(MinimalPlugins)
         .add_system(hello_world_system.system())
         .run();
 
     // this app loops forever at 60 fps
     App::build()
-        .add_plugin(ScheduleRunnerPlugin::run_loop(Duration::from_secs_f64(
+        .add_resource(ScheduleRunnerSettings::run_loop(Duration::from_secs_f64(
             1.0 / 60.0,
         )))
+        .add_plugin_group(MinimalPlugins)
         .add_system(counter.system())
         .run();
 }

examples/app/plugin.rs

@@ -6,7 +6,7 @@ use std::time::Duration;
 /// This example illustrates how to create a simple plugin that prints out a message.
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         // plugins are registered as part of the "app building" process
         .add_plugin(PrintMessagePlugin {
             wait_duration: Duration::from_secs(1),

examples/app/plugin_group.rs

@@ -3,7 +3,7 @@ use bevy::{app::PluginGroupBuilder, prelude::*};
 /// PluginGroups are a way to group sets of plugins that should be registered together.
 fn main() {
     App::build()
-        // The app.add_default_plugins() you see in all of the examples is just an alias for this:
+        // Two PluginGroups that are included with bevy are DefaultPlugins and MinimalPlugins
         .add_plugin_group(DefaultPlugins)
         // Adding a plugin group adds all plugins in the group by default
         .add_plugin_group(HelloWorldPlugins)

examples/app/return_after_run.rs

@@ -7,15 +7,15 @@ fn main() {
             return_from_run: true,
         })
         .add_resource(ClearColor(Color::rgb(0.2, 0.2, 0.8)))
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .run();
     println!("Running another App.");
     App::build()
         .add_resource(WinitConfig {
             return_from_run: true,
         })
         .add_resource(ClearColor(Color::rgb(0.2, 0.8, 0.2)))
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .run();
     println!("Done.");
 }

examples/app/thread_pool_resources.rs

@@ -5,6 +5,6 @@ use bevy::prelude::*;
 fn main() {
     App::build()
         .add_resource(DefaultTaskPoolOptions::with_num_threads(4))
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .run();
 }

examples/asset/asset_loading.rs

@@ -4,7 +4,7 @@ use bevy::prelude::*;
 fn main() {
     App::build()
         .add_resource(Msaa { samples: 4 })
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_startup_system(setup.system())
         .run();
 }

examples/asset/custom_asset.rs

@@ -35,7 +35,7 @@ impl AssetLoader for CustomAssetLoader {
 
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .init_resource::<State>()
         .add_asset::<CustomAsset>()
         .init_asset_loader::<CustomAssetLoader>()

examples/asset/hot_asset_reloading.rs

@@ -5,7 +5,7 @@ use bevy::prelude::*;
 /// This example illustrates hot reloading mesh changes.
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_startup_system(setup.system())
         .run();
 }

examples/audio/audio.rs

@@ -3,7 +3,7 @@ use bevy::prelude::*;
 /// This example illustrates how to load and play an audio file
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_startup_system(setup.system())
         .run();
 }

examples/diagnostics/custom_diagnostic.rs

@@ -6,7 +6,7 @@ use bevy::{
 /// This example illustrates how to create a custom diagnostic
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         // The "print diagnostics" plugin is optional. It just visualizes our diagnostics in the console
         .add_plugin(PrintDiagnosticsPlugin::default())
         .add_startup_system(setup_diagnostic_system.system())

examples/diagnostics/print_diagnostics.rs

@@ -5,7 +5,7 @@ use bevy::{
 
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         // Adds frame time diagnostics
         .add_plugin(FrameTimeDiagnosticsPlugin::default())
         // Adds a system that prints diagnostics to the console

examples/ecs/ecs_guide.rs

@@ -1,5 +1,5 @@
 use bevy::{
-    app::{AppExit, ScheduleRunnerPlugin},
+    app::{AppExit, ScheduleRunnerPlugin, ScheduleRunnerSettings},
     prelude::*,
 };
 use rand::random;
@@ -244,12 +244,14 @@ fn local_state_system(mut state: Local<State>, query: Query<(&Player, &Score)>)
 fn main() {
     // Bevy apps are created using the builder pattern. We use the builder to add systems, resources, and plugins to our app
     App::build()
-        // Plugins are just a grouped set of app builder calls (just like we're doing here).
-        // We could easily turn our game into a plugin, but you can check out the plugin example for that :)
-        // The plugin below runs our app's "system schedule" once every 5 seconds.
-        .add_plugin(ScheduleRunnerPlugin::run_loop(Duration::from_secs(5)))
         // Resources can be added to our app like this
         .add_resource(State { counter: 0 })
+        // Some systems are configured by adding their settings as a resource
+        .add_resource(ScheduleRunnerSettings::run_loop(Duration::from_secs(5)))
+        // Plugins are just a grouped set of app builder calls (just like we're doing here).
+        // We could easily turn our game into a plugin, but you can check out the plugin example for that :)
+        // The plugin below runs our app's "system schedule" once every 5 seconds (configured above).
+        .add_plugin(ScheduleRunnerPlugin::default())
         // Resources that implement the Default or FromResources trait can be added like this:
         .init_resource::<GameState>()
         // Startup systems run exactly once BEFORE all other systems. These are generally used for

examples/ecs/event.rs

@@ -4,7 +4,7 @@ use bevy::prelude::*;
 /// and a system that prints a message whenever the event is received.
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_event::<MyEvent>()
         .init_resource::<EventTriggerState>()
         .add_system(event_trigger_system.system())

examples/ecs/hierarchy.rs

@@ -2,7 +2,7 @@ use bevy::prelude::*;
 
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_startup_system(setup.system())
         .add_system(rotate.system())
         .run();

examples/ecs/parallel_query.rs

@@ -73,7 +73,7 @@ fn bounce_system(
 
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_startup_system(spawn_system.system())
         .add_system(move_system.system())
         .add_system(bounce_system.system())

examples/game/breakout.rs

@@ -7,7 +7,7 @@ use bevy::{
 /// An implementation of the classic game "Breakout"
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_resource(Scoreboard { score: 0 })
         .add_resource(ClearColor(Color::rgb(0.9, 0.9, 0.9)))
         .add_startup_system(setup.system())

examples/input/gamepad_input.rs

@@ -4,7 +4,7 @@ use bevy_utils::HashSet;
 
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .init_resource::<GamepadLobby>()
         .add_system_to_stage(stage::PRE_UPDATE, connection_system.system())
         .add_system(gamepad_system.system())

examples/input/gamepad_input_events.rs

@@ -3,7 +3,7 @@ use bevy_input::gamepad::{GamepadEvent, GamepadEventType};
 
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_system(gamepad_events.system())
         .run();
 }

examples/input/keyboard_input.rs

@@ -5,7 +5,7 @@ use bevy::{
 
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_system(keyboard_input_system.system())
         .run();
 }

examples/input/keyboard_input_events.rs

@@ -2,7 +2,7 @@ use bevy::{input::keyboard::KeyboardInput, prelude::*};
 
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_system(print_keyboard_event_system.system())
         .run();
 }

examples/input/mouse_input.rs

@@ -2,7 +2,7 @@ use bevy::prelude::*;
 
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_system(mouse_click_system.system())
         .run();
 }

examples/input/mouse_input_events.rs

@@ -6,7 +6,7 @@ use bevy::{
 
 fn main() {
     App::build()
-        .add_default_plugins()
+        .add_plugin_group(DefaultPlugins)
         .add_system(print_mouse_events_system.system())
         .run();
 }