Enable collision sensing for bodyless entities

Rapier expects to have a RigidBody attached to the entity, but I do not.

I'm not going to make one, either, because the objects in a game of
Asteroids don't need collision handling the way most games do. I just
need to know if two objects have started overlapping.

According to this: https://rapier.rs/docs/user_guides/bevy_plugin/colliders#collision-groups-and-solver-groups
only one of the two objects involved needs to have the ActiveEvents and
ActiveCollisionTypes components attached, so I've placed them on the
player ship.

src/asteroids.rs

@@ -1,4 +1,4 @@
-use bevy_rapier2d::prelude::Collider;
+use bevy_rapier2d::prelude::*;
 use rand::{Rng, SeedableRng};
 use std::time::Duration;
 
@@ -118,6 +118,7 @@ pub fn spawn_asteroid(
         commands.spawn((
             Asteroid(AsteroidSize::Small),
             Collider::ball(collider_radius),
+            Sensor,
             Position(spawn.pos),
             Velocity(spawn.vel),
             Rotation(0.0),

src/lib.rs

@@ -10,7 +10,11 @@ use bevy::prelude::*;
 use bevy_inspector_egui::InspectorOptions;
 use bevy_inspector_egui::prelude::ReflectInspectorOptions;
 
-use bevy_rapier2d::{plugin::{NoUserData, RapierPhysicsPlugin}, prelude::Collider, render::RapierDebugRenderPlugin};
+use bevy_rapier2d::{
+    plugin::{NoUserData, RapierPhysicsPlugin},
+    prelude::*,
+    render::RapierDebugRenderPlugin,
+};
 use config::{ASTEROID_SMALL_COLOR, SHIP_THRUSTER_COLOR_ACTIVE, SHIP_THRUSTER_COLOR_INACTIVE};
 
 pub struct AsteroidPlugin;
@@ -43,6 +47,8 @@ impl Plugin for AsteroidPlugin {
                 wrap_entities,
                 asteroids::tick_asteroid_manager,
                 asteroids::spawn_asteroid.after(asteroids::tick_asteroid_manager),
+                // TODO: Remove debug printing
+                debug_collision_event_printer,
             )
                 .run_if(in_state(GameState::Playing)),
         )
@@ -56,6 +62,12 @@ impl Plugin for AsteroidPlugin {
     }
 }
 
+fn debug_collision_event_printer(mut collision_events: EventReader<CollisionEvent>) {
+    for event in collision_events.read() {
+        dbg!(event);
+    }
+}
+
 #[derive(Clone, Debug, Eq, Hash, PartialEq, States)]
 pub enum GameState {
     TitleScreen, // Program is started. Present title screen and await user start
@@ -180,6 +192,9 @@ fn spawn_player(mut commands: Commands, game_assets: Res<GameAssets>) {
     commands
         .spawn((
             Collider::ball(0.7),
+            Sensor,
+            ActiveEvents::COLLISION_EVENTS,
+            ActiveCollisionTypes::STATIC_STATIC,
             Ship,
             Wrapping,
             Position(Vec2::default()),