Bevy Book: Resources

hello-world/src/people.rs

@@ -1,15 +1,20 @@
+use std::time::Duration;
+
 use bevy::{
-    app::{Startup, Update},
+    prelude::{App, Commands, Component, Query, Res, ResMut, Resource, Startup, Update, With},
-    prelude::{App, Commands, Component, Query, With},
+    time::{Time, TimerMode},
 };
 
 pub struct Plugin;
 
 impl bevy::app::Plugin for Plugin {
     fn build(&self, app: &mut App) {
-        #[rustfmt::skip]
+        app.insert_resource(Timer(bevy::time::Timer::from_seconds(
-        app.add_systems(Startup, startup)
+            2.0,
-            .add_systems(Update, greet);
+            TimerMode::Repeating,
+        )))
+        .add_systems(Startup, startup)
+        .add_systems(Update, greet);
     }
 }
 
@@ -25,14 +30,25 @@ impl Name {
     }
 }
 
+#[derive(Resource)]
+struct Timer(bevy::time::Timer);
+
+impl Timer {
+    fn tick(&mut self, delta: Duration) -> &bevy::time::Timer {
+        self.0.tick(delta)
+    }
+}
+
 fn startup(mut cmds: Commands) {
     cmds.spawn((Person, Name::new("Elaina Proctor")));
     cmds.spawn((Person, Name::new("Renzo Hume")));
     cmds.spawn((Person, Name::new("Zayna Nieves")));
 }
 
-fn greet(q: Query<&Name, With<Person>>) {
+fn greet(time: Res<Time>, mut timer: ResMut<Timer>, q: Query<&Name, With<Person>>) {
-    for name in &q {
+    if timer.tick(time.delta()).just_finished() {
-        println!("Hello, {}!", name.0);
+        for name in &q {
+            println!("Hello, {}!", name.0);
+        }
     }
 }