Don't update if physics is paused.

src/visibility.rs

@@ -311,6 +311,7 @@ impl InputGrid for VisibilityGrid {
 
 fn update_viewshed(
     mut commands: Commands,
+    physics_time: Res<Time<Physics>>,
     mut viewers: Query<(
         Entity,
         &mut Viewshed,
@@ -321,6 +322,9 @@ fn update_viewshed(
     sensors: Query<&Sensor>,
     spatial_query: SpatialQuery,
 ) {
+    if physics_time.is_paused() {
+        return;
+    }
     for (viewer_entity, mut viewshed, mut visible_entities, viewer_transform) in &mut viewers {
         viewshed.update(
             &mut commands,