683 fix context swapping failing in non postupdate schedule

bevy_rapier3d/examples/change_contexts3.rs

@@ -0,0 +1,126 @@
+use bevy::prelude::*;
+use bevy_rapier3d::prelude::*;
+
+const N_CONTEXTS: usize = 5;
+const WORLD_CHANGE_DELAY_SEC: f32 = 3.0;
+
+#[derive(Component)]
+/// Denotes which object(s) to change the world of
+struct ChangeWorld;
+
+#[derive(Resource, Debug)]
+struct Contexts(Vec<Entity>);
+
+fn main() {
+    App::new()
+        .insert_resource(ClearColor(Color::linear_rgb(
+            0xF9 as f32 / 255.0,
+            0xF9 as f32 / 255.0,
+            0xFF as f32 / 255.0,
+        )))
+        .add_plugins((
+            DefaultPlugins,
+            RapierPhysicsPlugin::<NoUserData>::default(),
+            RapierDebugRenderPlugin::default(),
+        ))
+        .add_systems(Startup, (setup_graphics, setup_physics))
+        .add_systems(Update, change_world)
+        .run();
+}
+
+fn change_world(
+    mut query: Query<&mut RapierContextEntityLink, With<ChangeWorld>>,
+    time: Res<Time>,
+    worlds: Res<Contexts>,
+) {
+    for mut context_entity_link in query.iter_mut() {
+        let idx = (worlds.0.len() - 1).min((time.elapsed_secs() / WORLD_CHANGE_DELAY_SEC) as usize);
+
+        // Prevent needless change detection
+        if context_entity_link.0 != worlds.0[idx] {
+            context_entity_link.0 = worlds.0[idx];
+            info!(
+                "Changing context to {:?} ({}/{N_CONTEXTS})",
+                context_entity_link.0,
+                idx + 1
+            )
+        }
+    }
+}
+
+fn setup_graphics(mut commands: Commands) {
+    commands.spawn((
+        Camera3d::default(),
+        Transform::from_xyz(0.0, 3.0, -10.0).looking_at(Vec3::new(0.0, 0.0, 0.0), Vec3::Y),
+    ));
+}
+
+pub fn setup_physics(
+    mut commands: Commands,
+    q_default_context: Query<Entity, With<DefaultRapierContext>>,
+) {
+    let default_context = q_default_context
+        .single()
+        .expect("This will automatically be created");
+
+    let mut contexts = Contexts(vec![default_context]);
+
+    for i in 1..N_CONTEXTS {
+        // Each context can have its own rapier configuration
+        let mut config = RapierConfiguration::new(1.0);
+        if i + 1 == N_CONTEXTS {
+            info!("The last context will have opposite gravity");
+            config.gravity = -config.gravity;
+        }
+        let context_ent = commands
+            .spawn((RapierContextSimulation::default(), config))
+            .id();
+        contexts.0.push(context_ent);
+    }
+
+    for (i, &world_ent) in contexts.0.iter().enumerate() {
+        let color = [
+            Color::hsl(220.0, 1.0, 0.3),
+            Color::hsl(180.0, 1.0, 0.3),
+            Color::hsl(260.0, 1.0, 0.7),
+        ][i % 3];
+
+        /*
+         * Ground
+         */
+        let ground_size = 5.1;
+        let ground_height = 0.1;
+
+        commands.spawn((
+            Transform::from_xyz(0.0, (i as f32) * -0.5 - ground_height, 0.0),
+            Collider::cuboid(ground_size, ground_height, ground_size),
+            ColliderDebugColor(color.into()),
+            RigidBody::Fixed,
+            RapierContextEntityLink(world_ent),
+        ));
+    }
+
+    /*
+     * Create the cube
+     *
+     * The child is just there to show that physics world changes will also change the children.
+     */
+    commands
+        .spawn((
+            // This will spawn in the default world, since no RapierContextEntityLink was added
+            Transform::from_xyz(0.0, 3.0, 0.0),
+            RigidBody::Dynamic,
+            ChangeWorld,
+        ))
+        .with_children(|p| {
+            p.spawn((
+                Transform::from_xyz(0.0, 0.0, 0.0),
+                Collider::cuboid(0.5, 0.5, 0.5),
+                ColliderDebugColor(Color::hsl(260.0, 1.0, 0.7).into()),
+            ));
+        });
+
+    info!("Spawning cube in default world (1/{N_CONTEXTS})");
+
+    commands.insert_resource(contexts);
+}

src/plugin/systems/remove.rs

@@ -27,6 +27,19 @@ pub fn sync_removals(
         &mut RapierContextJoints,
         &mut RapierRigidBodySet,
     )>,
+    // Sometimes a Remove immediately followed by Add happens. These `q_has_*` queries prevent that immediate Add
+    // from being removed by this system by verifying it's still removed.
+    (
+        q_has_rigidbody_handle,
+        q_has_collider_handle,
+        q_has_multibody_joint_handle,
+        q_has_impulse_joint_handle,
+    ): (
+        Query<(), With<RapierRigidBodyHandle>>,
+        Query<(), With<RapierColliderHandle>>,
+        Query<(), With<RapierMultibodyJointHandle>>,
+        Query<(), With<RapierImpulseJointHandle>>,
+    ),
     mut removed_bodies: RemovedComponents<RapierRigidBodyHandle>,
     mut removed_colliders: RemovedComponents<RapierColliderHandle>,
     mut removed_impulse_joints: RemovedComponents<RapierImpulseJointHandle>,
@@ -48,7 +61,10 @@ pub fn sync_removals(
     /*
      * Rigid-bodies removal detection.
      */
-    for entity in removed_bodies.read() {
+    for entity in removed_bodies
+        .read()
+        .filter(|e| !q_has_rigidbody_handle.contains(*e))
+    {
         let Some(((mut context, mut context_colliders, mut joints, mut rigidbody_set), handle)) =
             find_context(&mut context_writer, |res| res.3.entity2body.remove(&entity))
         else {
@@ -90,7 +106,10 @@ pub fn sync_removals(
     /*
      * Collider removal detection.
      */
-    for entity in removed_colliders.read() {
+    for entity in removed_colliders
+        .read()
+        .filter(|e| !q_has_collider_handle.contains(*e))
+    {
         let Some(((mut context, mut context_colliders, _, mut rigidbody_set), handle)) =
             find_context(&mut context_writer, |res| {
                 res.1.entity2collider.remove(&entity)
@@ -138,7 +157,10 @@ pub fn sync_removals(
     /*
      * Impulse joint removal detection.
      */
-    for entity in removed_impulse_joints.read() {
+    for entity in removed_impulse_joints
+        .read()
+        .filter(|e| !q_has_impulse_joint_handle.contains(*e))
+    {
         let Some(((_, _, mut joints, _), handle)) = find_context(&mut context_writer, |res| {
             res.2.entity2impulse_joint.remove(&entity)
         }) else {
@@ -159,7 +181,10 @@ pub fn sync_removals(
     /*
      * Multibody joint removal detection.
      */
-    for entity in removed_multibody_joints.read() {
+    for entity in removed_multibody_joints
+        .read()
+        .filter(|e| !q_has_multibody_joint_handle.contains(*e))
+    {
         let Some(((_, _, mut joints, _), handle)) = find_context(&mut context_writer, |res| {
             res.2.entity2multibody_joint.remove(&entity)
         }) else {