Remove add_default_plugins and add MinimalPlugins for simple "headless" scenarios (#767)

Remove add_default_plugins and add MinimalPlugins for simple "headless" scenarios

Author: CleanCut

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();
 }