Ungrab mouse when window loses focus

src/camera_controller.rs

@@ -29,13 +29,14 @@ fn capture_mouse(
     key: Res<ButtonInput<KeyCode>>,
 ) {
     if mouse.just_pressed(MouseButton::Left) {
-        window.cursor_options.visible = false;
+        set_mouse_grabbed(&mut window, true);
-        window.cursor_options.grab_mode = CursorGrabMode::Locked;
     }
-
     if key.just_pressed(KeyCode::Escape) {
-        window.cursor_options.visible = true;
+        set_mouse_grabbed(&mut window, false);
-        window.cursor_options.grab_mode = CursorGrabMode::None;
+    }
+    // Ungrab the mouse if window doesn't have focus.
+    if !window.focused {
+        set_mouse_grabbed(&mut window, false);
     }
 }
 
@@ -45,7 +46,7 @@ fn camera_mouse_rotation(
     mouse_motion: Res<AccumulatedMouseMotion>,
 ) {
     // Mouse must be grabbed by the window for this system to run.
-    if window.cursor_options.grab_mode != CursorGrabMode::Locked {
+    if !mouse_grabbed(&window) {
         return;
     }
 
@@ -71,7 +72,7 @@ fn camera_keyboard_translation(
     key: Res<ButtonInput<KeyCode>>,
 ) {
     // Mouse must be grabbed by the window for this system to run.
-    if window.cursor_options.grab_mode != CursorGrabMode::Locked {
+    if !mouse_grabbed(&window) {
         return;
     }
 
@@ -108,3 +109,16 @@ fn camera_keyboard_translation(
         transform.translation += translation;
     }
 }
+
+fn mouse_grabbed(window: &Window) -> bool {
+    window.cursor_options.grab_mode == CursorGrabMode::Locked
+}
+
+fn set_mouse_grabbed(window: &mut Window, value: bool) {
+    window.cursor_options.visible = !value;
+    window.cursor_options.grab_mode = if value {
+        CursorGrabMode::Locked
+    } else {
+        CursorGrabMode::None
+    };
+}