fix: cannot move when no gl context

crates/bevy_app/src/app.rs

@@ -78,6 +78,7 @@ pub struct App {
     /// This is initially set to [`Main`].
     pub main_schedule_label: InternedScheduleLabel,
     sub_apps: HashMap<InternedAppLabel, SubApp>,
+    run_sub_apps: bool,
     plugin_registry: Vec<Box<dyn Plugin>>,
     plugin_name_added: HashSet<String>,
     /// A private counter to prevent incorrect calls to `App::run()` from `Plugin::build()`
@@ -238,6 +239,7 @@ impl App {
             world,
             runner: Box::new(run_once),
             sub_apps: HashMap::default(),
+            run_sub_apps: true,
             plugin_registry: Vec::default(),
             plugin_name_added: Default::default(),
             main_schedule_label: Main.intern(),
@@ -265,11 +267,13 @@ impl App {
             let _bevy_main_update_span = info_span!("main app").entered();
             self.world.run_schedule(self.main_schedule_label);
         }
-        for (_label, sub_app) in &mut self.sub_apps {
-            #[cfg(feature = "trace")]
-            let _sub_app_span = info_span!("sub app", name = ?_label).entered();
-            sub_app.extract(&mut self.world);
-            sub_app.run();
+        if self.run_sub_apps {
+            for (_label, sub_app) in &mut self.sub_apps {
+                #[cfg(feature = "trace")]
+                let _sub_app_span = info_span!("sub app", name = ?_label).entered();
+                sub_app.extract(&mut self.world);
+                sub_app.run();
+            }
         }
 
         self.world.clear_trackers();
@@ -815,6 +819,16 @@ impl App {
         self.sub_apps.insert(label.intern(), sub_app);
     }
 
+    /// Resumes sub apps
+    pub fn resume_sub_apps(&mut self) {
+        self.run_sub_apps = true;
+    }
+
+    /// Pauses sub apps from running.
+    pub fn pause_sub_apps(&mut self) {
+        self.run_sub_apps = false;
+    }
+
     /// Removes a sub app from the app. Returns [`None`] if the label doesn't exist.
     pub fn remove_sub_app(&mut self, label: impl AppLabel) -> Option<SubApp> {
         self.sub_apps.remove(&label.intern())

crates/bevy_winit/src/lib.rs

@@ -811,7 +811,7 @@ pub fn winit_runner(mut app: App) {
                     }
                     let (config, windows) = focused_windows_state.get(&app.world);
                     let focused = windows.iter().any(|(_, window)| window.focused);
-                    let mut should_update = match config.update_mode(focused) {
+                    let should_update = match config.update_mode(focused) {
                         UpdateMode::Continuous | UpdateMode::Reactive { .. } => {
                             // `Reactive`: In order for `event_handler` to have been called, either
                             // we received a window or raw input event, the `wait` elapsed, or a
@@ -861,7 +861,9 @@ pub fn winit_runner(mut app: App) {
                         {
                             if !has_gl_context(&window) {
                                 app.world.send_event(WindowGlContextLost { window: entity });
-                                should_update = false;
+                                // HEP: pause sub-apps to stop WGPU from crashing when there's no OpenGL context.
+                                // Ensures that the rest of the systems in the main app keep running (i.e. physics).
+                                app.pause_sub_apps();
                             }
                         }
                     }