add IgnoredCollisions component

src/collision/broad_phase.rs

@@ -182,6 +182,7 @@ fn collect_collision_pairs(
     intervals: ResMut<AabbIntervals>,
     mut broad_collision_pairs: ResMut<BroadCollisionPairs>,
     mut aabb_intersection_query: Query<&mut AabbIntersections>,
+    ignored_collisions: Query<&IgnoredCollisions>,
 ) {
     for mut intersections in &mut aabb_intersection_query {
         intersections.clear();
@@ -191,6 +192,7 @@ fn collect_collision_pairs(
         intervals,
         &mut broad_collision_pairs.0,
         &mut aabb_intersection_query,
+        ignored_collisions,
     );
 }
 
@@ -201,6 +203,7 @@ fn sweep_and_prune(
     mut intervals: ResMut<AabbIntervals>,
     broad_collision_pairs: &mut Vec<(Entity, Entity)>,
     aabb_intersection_query: &mut Query<&mut AabbIntersections>,
+    ignored_collisions: Query<&IgnoredCollisions>,
 ) {
     // Sort bodies along the x-axis using insertion sort, a sorting algorithm great for sorting nearly sorted lists.
     insertion_sort(&mut intervals.0, |a, b| a.2.min.x > b.2.min.x);
@@ -212,9 +215,29 @@ fn sweep_and_prune(
     for (i, (ent1, parent1, aabb1, layers1, store_intersections1, inactive1)) in
         intervals.0.iter().enumerate()
     {
+        let ent1_ignored_collisions = ignored_collisions.get(*ent1).ok();
         for (ent2, parent2, aabb2, layers2, store_intersections2, inactive2) in
             intervals.0.iter().skip(i + 1)
         {
+            // Check ignored collisions of `ent1`
+            if ent1_ignored_collisions
+                .as_ref()
+                .map(|i| i.contains(ent2))
+                .unwrap_or_default()
+            {
+                continue;
+            }
+
+            // Check ignored collisions of `ent2`
+            let ent2_ignored_collisions = ignored_collisions.get(*ent2).ok();
+            if ent2_ignored_collisions
+                .as_ref()
+                .map(|i| i.contains(ent1))
+                .unwrap_or_default()
+            {
+                continue;
+            }
+
             // x doesn't intersect; check this first so we can discard as soon as possible
             if aabb2.min.x > aabb1.max.x {
                 break;

src/collision/collider/parry/mod.rs

@@ -262,7 +262,7 @@ impl From<TrimeshFlags> for parry::shape::TriMeshFlags {
 /// ```
 ///
 /// Colliders can be further configured using various components like [`Friction`], [`Restitution`],
-/// [`Sensor`], [`CollisionLayers`], and [`CollisionMargin`].
+/// [`Sensor`], [`IgnoredCollisions`], [`CollisionLayers`], and [`CollisionMargin`].
 ///
 /// In addition, Avian automatically adds some other components for colliders, like the following:
 ///
@@ -344,6 +344,7 @@ impl From<TrimeshFlags> for parry::shape::TriMeshFlags {
 /// - [Rigid bodies](RigidBody)
 /// - [Density](ColliderDensity)
 /// - [Friction] and [restitution](Restitution) (bounciness)
+/// - [Ignoring collisions](IgnoredCollisions)
 /// - [Collision layers](CollisionLayers)
 /// - [Sensors](Sensor)
 /// - [Collision margins for adding extra thickness to colliders](CollisionMargin)

src/collision/layers.rs

@@ -257,6 +257,8 @@ impl Not for LayerMask {
 ///
 /// [bitmasks]: https://en.wikipedia.org/wiki/Mask_(computing)
 ///
+/// See also [`IgnoredCollisions`](crate::components::IgnoredCollisions).
+///
 /// ## Creation
 ///
 /// Collision layers store memberships and filters using [`LayerMask`]s. A [`LayerMask`] can be created using

src/collision/mod.rs

@@ -68,6 +68,12 @@ use indexmap::IndexMap;
 /// The collisions can be accessed at any time, but modifications to contacts should be performed
 /// in the [`PostProcessCollisions`] schedule. Otherwise, the physics solver will use the old contact data.
 ///
+/// ### Ignoring collisions
+///
+/// You can attach an [`IgnoredCollisions`] component to an entity with a
+/// [`Collider`] to completely avoid collision detection between the entity and
+/// the entities contained within the [`IgnoredCollisions`] component.
+///
 /// ### Filtering and removing collisions
 ///
 /// The following methods can be used for filtering or removing existing collisions:

src/dynamics/rigid_body/mod.rs

@@ -16,7 +16,7 @@ pub(crate) use forces::FloatZero;
 pub(crate) use forces::Torque;
 
 use crate::prelude::*;
-use bevy::prelude::*;
+use bevy::{prelude::*, utils::HashSet};
 use derive_more::From;
 
 /// A non-deformable body used for the simulation of most physics objects.
@@ -826,6 +826,63 @@ pub struct AngularDamping(pub Scalar);
 #[reflect(Debug, Component, Default, PartialEq)]
 pub struct Dominance(pub i8);
 
+/// A component containing a set of entities for which any collisions with the
+/// owning entity will be ignored.
+///
+/// ## Example
+///
+/// ```
+/// use bevy::prelude::*;
+/// # #[cfg(feature = "2d")]
+/// # use bevy_xpbd_2d::prelude::*;
+/// # #[cfg(feature = "3d")]
+/// use bevy_xpbd_3d::prelude::*;
+///
+/// fn setup(mut commands: Commands) {
+///     // Spawn an entity with a collider
+#[cfg_attr(
+    feature = "2d",
+    doc = "    let ent1 = commands",
+    doc = "        .spawn((RigidBody::Dynamic, Collider::circle(0.5)))",
+    doc = "        .id();"
+)]
+#[cfg_attr(
+    feature = "3d",
+    doc = "    let ent1 = commands",
+    doc = "       .spawn((RigidBody::Dynamic, Collider::sphere(0.5)))",
+    doc = "       .id();"
+)]
+///
+///     // Spawn another entity with a collider and configure it to avoid collisions with the first entity.
+#[cfg_attr(
+    feature = "2d",
+    doc = "    let ent1 = commands.spawn((",
+    doc = "        RigidBody::Dynamic,",
+    doc = "        Collider::circle(0.5),",
+    doc = "        IgnoredCollisions::from_iter([ent1]),",
+    doc = "));"
+)]
+#[cfg_attr(
+    feature = "3d",
+    doc = "    let ent1 = commands.spawn((",
+    doc = "        RigidBody::Dynamic,",
+    doc = "        Collider::sphere(0.5),",
+    doc = "        IgnoredCollisions::from_iter([ent1]),",
+    doc = "    ));"
+)]
+/// }
+/// ```
+///
+/// See also [`CollisionLayers`].
+#[derive(Component, Clone, Debug, Default, Deref, DerefMut)]
+pub struct IgnoredCollisions(pub HashSet<Entity>);
+
+impl FromIterator<Entity> for IgnoredCollisions {
+    fn from_iter<T: IntoIterator<Item = Entity>>(iter: T) -> Self {
+        Self(HashSet::from_iter(iter))
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::prelude::*;

src/lib.rs

@@ -140,6 +140,7 @@
 //!     - [Creation](Collider#creation)
 //!     - [Density](ColliderDensity)
 //!     - [Friction] and [restitution](Restitution) (bounciness)
+//!     - [Ignoring collisions](IgnoredCollisions)
 //!     - [Collision layers](CollisionLayers)
 //!     - [Sensors](Sensor)
 #![cfg_attr(