added pause and resume simulation

src/game/mod.rs

@@ -19,22 +19,28 @@ pub struct GamePlugin;
 
 impl Plugin for GamePlugin {
     fn build(&self, app: &mut App) {
-        app.add_state::<SimulationState>()
+        app
             // Events
             .add_event::<GameOver>()
-            // Plugins
+            // States
+            .add_state::<SimulationState>()
+            // OnEnter Systems
+            .add_system(pause_simulation.in_schedule(OnEnter(AppState::Game)))
+            // My Plugins
             .add_plugin(EnemyPlugin)
             .add_plugin(PlayerPlugin)
             .add_plugin(ScorePlugin)
             .add_plugin(StarPlugin)
             // Systems
-            .add_system(toggle_simulation.run_if(in_state(AppState::Game)));
+            .add_system(toggle_simulation.run_if(in_state(AppState::Game)))
+            // Exit State Systems
+            .add_system(resume_simulation.in_schedule(OnExit(AppState::Game)));
     }
 }
 
 #[derive(States, Debug, Clone, Copy, Eq, PartialEq, Hash, Default)]
 pub enum SimulationState {
-    Running,
     #[default]
+    Running,
     Paused,
 }

src/game/systems.rs

@@ -2,6 +2,14 @@ use bevy::prelude::*;
 
 use crate::game::SimulationState;
 
+pub fn pause_simulation(mut simulation_state_next_state: ResMut<NextState<SimulationState>>) {
+    simulation_state_next_state.set(SimulationState::Paused);
+}
+
+pub fn resume_simulation(mut simulation_state_next_state: ResMut<NextState<SimulationState>>) {
+    simulation_state_next_state.set(SimulationState::Running);
+}
+
 pub fn toggle_simulation(
     keyboard_input: Res<Input<KeyCode>>,
     simulation_state: Res<State<SimulationState>>,

src/systems.rs

@@ -3,7 +3,6 @@ use bevy::prelude::*;
 use bevy::window::PrimaryWindow;
 
 use crate::events::*;
-use crate::game::SimulationState;
 use crate::AppState;
 
 pub fn spawn_camera(mut commands: Commands, window_query: Query<&Window, With<PrimaryWindow>>) {