Add placeholder alien with animations (#1)

src/alien.rs

@@ -0,0 +1,86 @@
+use std::time::Duration;
+
+use bevy::prelude::*;
+
+const FOX_PATH: &str = "models/alien_naked.glb";
+
+#[derive(Resource)]
+struct Animations {
+    animations: Vec<AnimationNodeIndex>,
+    graph: Handle<AnimationGraph>,
+}
+
+pub fn plugin(app: &mut App) {
+    app.add_systems(Startup, setup);
+    app.add_systems(Update, (setup_once_loaded, toggle_animation));
+}
+
+fn setup(
+    mut commands: Commands,
+    asset_server: Res<AssetServer>,
+    mut graphs: ResMut<Assets<AnimationGraph>>,
+) {
+    // Build the animation graph
+    let (graph, node_indices) = AnimationGraph::from_clips([
+        asset_server.load(GltfAssetLabel::Animation(1).from_asset(FOX_PATH)),
+        asset_server.load(GltfAssetLabel::Animation(0).from_asset(FOX_PATH)),
+    ]);
+
+    // Insert a resource with the current scene information
+    let graph_handle = graphs.add(graph);
+    commands.insert_resource(Animations {
+        animations: node_indices,
+        graph: graph_handle,
+    });
+
+    // Fox
+    commands
+        .spawn(SceneRoot(
+            asset_server.load(GltfAssetLabel::Scene(0).from_asset(FOX_PATH)),
+        ))
+        .insert(Name::from("Alien"));
+}
+
+fn setup_once_loaded(
+    mut commands: Commands,
+    animations: Res<Animations>,
+    mut players: Query<(Entity, &mut AnimationPlayer), Added<AnimationPlayer>>,
+) {
+    for (entity, mut player) in &mut players {
+        let mut transitions = AnimationTransitions::new();
+
+        // Make sure to start the animation via the `AnimationTransitions`
+        // component. The `AnimationTransitions` component wants to manage all
+        // the animations and will get confused if the animations are started
+        // directly via the `AnimationPlayer`.
+        transitions
+            .play(&mut player, animations.animations[1], Duration::ZERO)
+            .repeat();
+
+        commands
+            .entity(entity)
+            .insert(AnimationGraphHandle(animations.graph.clone()))
+            .insert(transitions);
+    }
+}
+
+fn toggle_animation(
+    animations: Res<Animations>,
+    mut transitions: Query<(&mut AnimationTransitions, &mut AnimationPlayer)>,
+    keys: Res<ButtonInput<KeyCode>>,
+    mut animation_index: Local<u32>,
+) {
+    if keys.just_pressed(KeyCode::KeyE) {
+        for (mut transition, mut player) in &mut transitions {
+            transition
+                .play(
+                    &mut player,
+                    animations.animations[*animation_index as usize],
+                    Duration::from_secs(1),
+                )
+                .repeat();
+        }
+
+        *animation_index ^= 1; // Toggle between 0 and 1
+    }
+}