refactor(examples): adapt to new entity system

examples/simple_text.rs

@@ -1,5 +1,12 @@
 use comet::prelude::*;
 
+// A general state struct that caches known/static EntityIds
+// In this example we just cache the EntityId for the text entity
+#[derive(Default)]
+struct TextState {
+    text: EntityId,
+}
+
 fn setup(app: &mut App, renderer: &mut Renderer2D) {
     renderer.init_atlas();
     // Loading the font from the res/fonts directory with a rendered size of 77px
@@ -24,6 +31,11 @@ fn setup(app: &mut App, renderer: &mut Renderer2D) {
             sRgba::<f32>::from_hex("#abb2bfff"),    // Color of the text
         ),
     );
+
+    // Cache text entity in game state
+    if let Some(state) = app.game_state_mut::<TextState>() {
+        state.text = text;
+    }
 }
 
 #[allow(unused_variables)]
@@ -32,9 +44,12 @@ fn update(app: &mut App, renderer: &mut Renderer2D, dt: f32) {
     let size = renderer.size();
 
     // Recalculating the position of the text every frame to ensure the same relative position
-    let transform = app.get_component_mut::<Transform2D>(1).unwrap();
-    transform.position_mut().set_x(-((size.width - 50) as f32));
-    transform.position_mut().set_y((size.height - 100) as f32);
+    if let Some(state) = app.game_state::<TextState>() {
+        if let Some(transform) = app.get_component_mut::<Transform2D>(state.text) {
+            transform.position_mut().set_x(-((size.width - 50) as f32));
+            transform.position_mut().set_y((size.height - 100) as f32);
+        }
+    }
 
     renderer.render_scene_2d(app.scene_mut());
 }
@@ -42,6 +57,7 @@ fn update(app: &mut App, renderer: &mut Renderer2D, dt: f32) {
 fn main() {
     App::new()
         .with_preset(App2D)
+        .with_game_state(TextState::default())
         .with_title("Simple Text")
         .run::<Renderer2D>(setup, update);
 }