The bird is moving along

src/bin/flappy/main.rs

@@ -91,7 +91,8 @@ fn init_bird(
     let physics = (
         RigidBody::Dynamic,
         Collider::capsule(1.0, 1.0), Mass(1.0),
-        ExternalForce::default().with_persistence(false),
+        ExternalForce::new(Vec3::X * 1.0).with_persistence(true),
+        ExternalImpulse::default().with_persistence(false),
         LockedAxes::ROTATION_LOCKED.lock_translation_z(),
     );
 
@@ -113,7 +114,7 @@ fn init_ground(
         ..default()
     }));
 
-    let mesh = Mesh3d(meshes.add(Cuboid::new(5.0, 1.0, 1.0)));
+    let mesh = Mesh3d(meshes.add(Cuboid::new(10.0, 1.0, 1.0)));
 
     let name = Name::new("ground");
 
@@ -149,7 +150,7 @@ fn init_ui(
 fn flap(
     #[cfg(debug_assertions)] state: Res<State<PlayerState>>,
     #[cfg(debug_assertions)] keycode: Res<ButtonInput<KeyCode>>,
-    mut bird: Query<(&Transform, &mut ExternalForce), With<Bird>>,
+    mut bird: Query<(&Transform, &mut ExternalImpulse), With<Bird>>,
 ) {
     debug_assert!(
         matches!(state.get(), PlayerState::Alive),
@@ -161,7 +162,7 @@ fn flap(
     );
 
     bird.iter_mut().for_each(|(t, mut f)| {
-        f.apply_force(t.rotation * Vec3::NEG_Z * 500.0);
+        f.apply_impulse(t.rotation * Vec3::NEG_Z * 5.0);
     });
 }