Simple 2d/3d toggle

src/main.rs

@@ -8,7 +8,10 @@ mod prelude;
 
 use std::time::Duration;
 
-use bevy::asset::ChangeWatcher;
+use bevy::{
+    asset::ChangeWatcher,
+    input::{keyboard::KeyboardInput, ButtonState},
+};
 
 use crate::prelude::*;
 
@@ -19,8 +22,12 @@ fn main() {
 
     App::new()
         .add_state::<GameState>()
-        .add_systems(Update, state)
+        .add_systems(Update, state.run_if(resource_changed::<State<GameState>>()))
         .add_systems(Update, loading.run_if(in_state(GameState::Loading)))
+        .add_systems(
+            Update,
+            toggle_display_mode.run_if(on_event::<KeyboardInput>()),
+        )
         .add_plugins((
             DefaultPlugins
                 .set(ImagePlugin::default_nearest())
@@ -69,10 +76,27 @@ fn loading(
 }
 
 /// System for printing the current state
-fn state(state: Option<Res<State<GameState>>>) {
-    state.map(|s| {
-        if s.is_added() || s.is_changed() {
-            info!("State is {:?}", s);
+///
+/// Only runs when state is modified.
+fn state(state: Res<State<GameState>>) {
+    info!("State is {:?}", *state);
 }
-    });
+
+fn toggle_display_mode(
+    mut events: EventReader<KeyboardInput>,
+    state: Res<State<GameState>>,
+    mut next_state: ResMut<NextState<GameState>>,
+) {
+    events
+        .iter()
+        .filter(
+            |KeyboardInput {
+                 key_code, state, ..
+             }| (*key_code, *state) == (Some(KeyCode::Space), ButtonState::Pressed),
+        )
+        .for_each(|_| match state.get() {
+            GameState::Display2d => next_state.set(GameState::Display3d),
+            GameState::Display3d => next_state.set(GameState::Display2d),
+            _ => (),
+        })
 }