Fix SleepingPlugin not being optional and refactor logic (#624)

# Objective

Avian 0.2.0 has a regression from 0.1 where the `TimeSleeping` component is required, but it is only added automatically (as a required component) if the `SleepingPlugin` is enabled. This means that disabling the `SleepingPlugin` breaks physics.

## Solution

Make `TimeSleeping` properly optional for rigid bodies.

I also added a `WakeUpBody` `Command` to clean up some logic and abstract away resetting `TimeSleeping`.

Author: Jondolf

crates/avian2d/examples/one_way_platform_2d.rs

@@ -174,9 +174,9 @@ fn pass_through_one_way_platform(
         if keyboard_input.pressed(KeyCode::ArrowDown) && keyboard_input.pressed(KeyCode::Space) {
             *pass_through_one_way_platform = PassThroughOneWayPlatform::Always;
 
-            // Wake up body when it's allowed to drop down.
+            // Wake up the body when it's allowed to drop down.
             // Otherwise it won't fall because gravity isn't simulated.
-            commands.entity(entity).remove::<Sleeping>();
+            commands.queue(WakeUpBody(entity));
         } else {
             *pass_through_one_way_platform = PassThroughOneWayPlatform::ByNormal;
         }

src/collision/collider/backend.rs

@@ -664,16 +664,18 @@ struct ColliderRemovalSystem(SystemId<In<ColliderParent>>);
 fn collider_removed(
     In(parent): In<ColliderParent>,
     mut commands: Commands,
-    mut mass_prop_query: Query<&mut TimeSleeping>,
+    mut sleep_query: Query<&mut TimeSleeping>,
 ) {
     let parent = parent.get();
 
-    if let Ok(mut time_sleeping) = mass_prop_query.get_mut(parent) {
-        let mut entity_commands = commands.entity(parent);
+    let Some(mut entity_commands) = commands.get_entity(parent) else {
+        return;
+    };
 
-        // Queue the parent entity for mass property recomputation.
-        entity_commands.insert(RecomputeMassProperties);
+    // Queue the parent entity for mass property recomputation.
+    entity_commands.insert(RecomputeMassProperties);
 
+    if let Ok(mut time_sleeping) = sleep_query.get_mut(parent) {
         // Wake up the rigid body since removing the collider could also remove active contacts.
         entity_commands.remove::<Sleeping>();
         time_sleeping.0 = 0.0;

src/collision/narrow_phase.rs

@@ -724,9 +724,9 @@ impl<C: AnyCollider> NarrowPhase<'_, '_, C> {
         // When an active body collides with a sleeping body, wake up the sleeping body.
         self.parallel_commands.command_scope(|mut commands| {
             if body1.is_sleeping {
-                commands.entity(body1.entity).remove::<Sleeping>();
+                commands.queue(WakeUpBody(body1.entity));
             } else if body2.is_sleeping {
-                commands.entity(body2.entity).remove::<Sleeping>();
+                commands.queue(WakeUpBody(body2.entity));
             }
         });
 

src/dynamics/mod.rs

@@ -87,7 +87,7 @@ pub mod prelude {
             },
             *,
         },
-        sleeping::{DeactivationTime, SleepingPlugin, SleepingThreshold},
+        sleeping::{DeactivationTime, SleepingPlugin, SleepingThreshold, WakeUpBody},
         solver::{
             joints::*,
             schedule::{SolverSchedulePlugin, SolverSet, SubstepCount, SubstepSchedule},

src/dynamics/rigid_body/world_query.rs

@@ -29,7 +29,7 @@ pub struct RigidBodyQuery {
     pub restitution: Option<&'static Restitution>,
     pub locked_axes: Option<&'static LockedAxes>,
     pub dominance: Option<&'static Dominance>,
-    pub time_sleeping: &'static mut TimeSleeping,
+    pub time_sleeping: Option<&'static mut TimeSleeping>,
     pub is_sleeping: Has<Sleeping>,
     pub is_sensor: Has<Sensor>,
 }

src/dynamics/sleeping/mod.rs

@@ -109,6 +109,24 @@ impl Default for DeactivationTime {
     }
 }
 
+/// A [`Command`] that wakes up a [rigid body](RigidBody) by removing the [`Sleeping`] component
+/// and resetting the [`TimeSleeping`] to zero.
+pub struct WakeUpBody(pub Entity);
+
+impl Command for WakeUpBody {
+    fn apply(self, world: &mut World) {
+        let Ok(mut entity_mut) = world.get_entity_mut(self.0) else {
+            return;
+        };
+
+        entity_mut.remove::<Sleeping>();
+
+        if let Some(mut time_sleeping) = entity_mut.get_mut::<TimeSleeping>() {
+            time_sleeping.0 = 0.0;
+        };
+    }
+}
+
 /// Adds the [`Sleeping`] component to bodies whose linear and anigular velocities have been
 /// under the [`SleepingThreshold`] for a duration indicated by [`DeactivationTime`].
 #[allow(clippy::type_complexity)]
@@ -205,7 +223,6 @@ pub(crate) fn wake_on_changed(
                 Ref<Rotation>,
                 Ref<LinearVelocity>,
                 Ref<AngularVelocity>,
-                &mut TimeSleeping,
             ),
             (
                 With<Sleeping>,
@@ -220,7 +237,7 @@ pub(crate) fn wake_on_changed(
         // These are not modified by the physics engine
         // and don't need special handling.
         Query<
-            (Entity, &mut TimeSleeping),
+            Entity,
             Or<(
                 Changed<ExternalForce>,
                 Changed<ExternalTorque>,
@@ -235,20 +252,18 @@ pub(crate) fn wake_on_changed(
 ) {
     let this_run = system_tick.this_run();
 
-    for (entity, pos, rot, lin_vel, ang_vel, mut time_sleeping) in &mut query.p0() {
+    for (entity, pos, rot, lin_vel, ang_vel) in &query.p0() {
         if is_changed_after_tick(pos, last_physics_tick.0, this_run)
             || is_changed_after_tick(rot, last_physics_tick.0, this_run)
             || is_changed_after_tick(lin_vel, last_physics_tick.0, this_run)
             || is_changed_after_tick(ang_vel, last_physics_tick.0, this_run)
         {
-            commands.entity(entity).remove::<Sleeping>();
-            time_sleeping.0 = 0.0;
+            commands.queue(WakeUpBody(entity));
         }
     }
 
-    for (entity, mut time_sleeping) in &mut query.p1() {
-        commands.entity(entity).remove::<Sleeping>();
-        time_sleeping.0 = 0.0;
+    for entity in &query.p1() {
+        commands.queue(WakeUpBody(entity));
     }
 }
 
@@ -259,13 +274,9 @@ fn is_changed_after_tick<C: Component>(component_ref: Ref<C>, tick: Tick, this_r
 
 /// Removes the [`Sleeping`] component from all sleeping bodies.
 /// Triggered automatically when [`Gravity`] is changed.
-fn wake_all_sleeping_bodies(
-    mut commands: Commands,
-    mut bodies: Query<(Entity, &mut TimeSleeping), With<Sleeping>>,
-) {
-    for (entity, mut time_sleeping) in &mut bodies {
-        commands.entity(entity).remove::<Sleeping>();
-        time_sleeping.0 = 0.0;
+fn wake_all_sleeping_bodies(mut commands: Commands, bodies: Query<Entity, With<Sleeping>>) {
+    for entity in &bodies {
+        commands.queue(WakeUpBody(entity));
     }
 }
 

src/dynamics/solver/xpbd/mod.rs

@@ -377,10 +377,13 @@ pub fn solve_constraint<C: XpbdConstraint<ENTITY_COUNT> + Component, const ENTIT
 
             // At least one of the participating bodies is active, so wake up any sleeping bodies
             for body in &mut bodies {
-                body.time_sleeping.0 = 0.0;
+                // Reset the sleep timer
+                if let Some(time_sleeping) = body.time_sleeping.as_mut() {
+                    time_sleeping.0 = 0.0;
+                }
 
                 if body.is_sleeping {
-                    commands.entity(body.entity).remove::<Sleeping>();
+                    commands.queue(WakeUpBody(body.entity));
                 }
             }