crates/border-wars/src/lib.rs

@@ -0,0 +1,12 @@
+//! The file that contains utility functions, enums, structs of the game.
+
+use bevy::prelude::*;
+use std::default::Default;
+
+#[derive(Debug, Clone, Copy, Default, Eq, PartialEq, Hash, States)]
+pub enum GameState {
+    #[default]
+    Menu,
+    Lobby,
+    Game,
+}

crates/border-wars/src/main.rs

@@ -1,13 +1,16 @@
 //! The main entry point of the game.
 
 use bevy::prelude::*;
+use lib::GameState;
 use menu::MenuPlugin;
 
+mod lib;
 mod menu;
 
 fn main() {
     App::new()
         .add_plugins(DefaultPlugins)
+        .add_state::<GameState>()
         .add_plugins(MenuPlugin)
         .run();
 }

crates/border-wars/src/menu.rs

@@ -2,6 +2,7 @@
 
 use bevy::prelude::*;
 use bevy_egui::{egui, EguiContexts, EguiPlugin};
+use border_wars::GameState;
 
 /// The plugin for the menu.
 pub struct MenuPlugin;
@@ -10,14 +11,19 @@ pub struct MenuPlugin;
 impl Plugin for MenuPlugin {
     /// A function that is called when the plugin is added to the application.
     fn build(&self, app: &mut App) {
-        app.add_plugins(EguiPlugin)
+        app.add_plugins(EguiPlugin).add_systems(Update,(
-            .add_systems(Update, ui_connect_window)
+            ui_connect_window.run_if(state_exists_and_equals(GameState::Menu)),
-            .add_systems(Update, ui_host_window);
+            ui_host_window.run_if(state_exists_and_equals(GameState::Menu)),
+        ));
     }
 }
 /// Display a connect window, with a button to join a game and an input to enter
 /// the address.
-fn ui_connect_window(mut ctx: EguiContexts, mut connection_string: Local<String>) {
+fn ui_connect_window(
+    mut ctx: EguiContexts,
+    mut connection_string: Local<String>,
+    mut state: ResMut<State<GameState>>,
+) {
     egui::Window::new("Connect")
         .default_width(400.0)
         .show(ctx.ctx_mut(), |ui| {