Implement interaction groups test mode and cofficient combine rule

CHANGELOG.md

@@ -10,6 +10,8 @@
 
 ### Added
 
+- `InteractionTestMode`: Specifies which method should be used to test interactions. Supports `AND` and `OR`.
+- `CoefficientCombineRule::Sum` - Adds the two coefficients and does a clamp to have at most 1.
 - `RigidBodySet` and `ColliderSet` have a new constructor `with_capacity`.
 - Use `profiling` crate to provide helpful profiling information in different tools.
   - The testbeds have been updated to use `puffin_egui`
@@ -19,6 +21,9 @@
 - `InteractionGroups` default value for `memberships` is now `GROUP_1` (#706)
 - `ImpulseJointSet::get_mut` has a new parameter `wake_up: bool`, to wake up connected bodies.
 - Removed unmaintained `instant` in favor of `web-time`. This effectively removes the `wasm-bindgen` transitive dependency as it's no longer needed.
+- `InteractionGroups` struct now contains `InteractionTestMode`. Continues [rapier/pull/170](https://github.com/dimforge/rapier/pull/170) for [rapier/issues/622](https://github.com/dimforge/rapier/issues/622)
+- `InteractionGroups` constructor now requires an `InteractionTestMode` parameter. If you want same behaviour as before, use `InteractionTestMode::And` (eg. `InteractionGroups::new(Group::GROUP_1, Group::GROUP_1, InteractionTestMode::And)`)
+- `CoefficientCombineRule::Min` - now makes sure it uses a non zero value as result by using `coeff1.min(coeff2).abs()`
 
 ## v0.22.0 (20 July 2024)
 

examples2d/collision_groups2.rs

@@ -24,8 +24,10 @@ pub fn init_world(testbed: &mut Testbed) {
     /*
      * Setup groups
      */
-    const GREEN_GROUP: InteractionGroups = InteractionGroups::new(Group::GROUP_1, Group::GROUP_1);
-    const BLUE_GROUP: InteractionGroups = InteractionGroups::new(Group::GROUP_2, Group::GROUP_2);
+    const GREEN_GROUP: InteractionGroups =
+        InteractionGroups::new(Group::GROUP_1, Group::GROUP_1, InteractionTestMode::And);
+    const BLUE_GROUP: InteractionGroups =
+        InteractionGroups::new(Group::GROUP_2, Group::GROUP_2, InteractionTestMode::And);
 
     /*
      * A green floor that will collide with the GREEN group only.

examples3d/collision_groups3.rs

@@ -24,8 +24,10 @@ pub fn init_world(testbed: &mut Testbed) {
     /*
      * Setup groups
      */
-    const GREEN_GROUP: InteractionGroups = InteractionGroups::new(Group::GROUP_1, Group::GROUP_1);
-    const BLUE_GROUP: InteractionGroups = InteractionGroups::new(Group::GROUP_2, Group::GROUP_2);
+    const GREEN_GROUP: InteractionGroups =
+        InteractionGroups::new(Group::GROUP_1, Group::GROUP_1, InteractionTestMode::And);
+    const BLUE_GROUP: InteractionGroups =
+        InteractionGroups::new(Group::GROUP_2, Group::GROUP_2, InteractionTestMode::And);
 
     /*
      * A green floor that will collide with the GREEN group only.

examples3d/vehicle_joints3.rs

@@ -53,7 +53,11 @@ pub fn init_world(testbed: &mut Testbed) {
 
     let body_co = ColliderBuilder::cuboid(0.65, 0.3, 0.9)
         .density(100.0)
-        .collision_groups(InteractionGroups::new(CAR_GROUP, !CAR_GROUP));
+        .collision_groups(InteractionGroups::new(
+            CAR_GROUP,
+            !CAR_GROUP,
+            InteractionTestMode::And,
+        ));
     let body_rb = RigidBodyBuilder::dynamic()
         .position(body_position.into())
         .build();
@@ -85,7 +89,11 @@ pub fn init_world(testbed: &mut Testbed) {
         // is mathematically simpler than a cylinder and cheaper to compute for collision-detection.
         let wheel_co = ColliderBuilder::ball(wheel_radius)
             .density(100.0)
-            .collision_groups(InteractionGroups::new(CAR_GROUP, !CAR_GROUP))
+            .collision_groups(InteractionGroups::new(
+                CAR_GROUP,
+                !CAR_GROUP,
+                InteractionTestMode::And,
+            ))
             .friction(1.0);
         let wheel_rb = RigidBodyBuilder::dynamic().position(wheel_center.into());
         let wheel_handle = bodies.insert(wheel_rb);

src/dynamics/coefficient_combine_rule.rs

@@ -19,6 +19,8 @@ pub enum CoefficientCombineRule {
     Multiply,
     /// The greatest coefficient is chosen.
     Max,
+    /// The sum of the two coefficients.
+    Sum,
 }
 
 impl CoefficientCombineRule {
@@ -27,8 +29,15 @@ impl CoefficientCombineRule {
 
         match effective_rule {
             0 => (coeff1 + coeff2) / 2.0,
-            1 => coeff1.min(coeff2),
+            1 => {
+                // Even though coeffs are meant to be positive, godot use-case has negative values.
+                // We're following their logic here.
+                // Context: https://github.com/dimforge/rapier/pull/741#discussion_r1862402948
+                coeff1.min(coeff2).abs()
+            }
             2 => coeff1 * coeff2,
+            4 => (coeff1 + coeff2).clamp(0.0, 1.0),
+            // 3 is missing as Max is the default one in case of mismatch.
             _ => coeff1.max(coeff2),
         }
     }

src/geometry/interaction_groups.rs

@@ -7,13 +7,18 @@
 /// - The interaction groups filter.
 ///
 /// An interaction is allowed between two filters `a` and `b` when two conditions
-/// are met simultaneously:
+/// are met simultaneously for [`InteractionTestMode::And`] or individually for [`InteractionTestMode::Or`]::
 /// - The groups membership of `a` has at least one bit set to `1` in common with the groups filter of `b`.
 /// - The groups membership of `b` has at least one bit set to `1` in common with the groups filter of `a`.
 ///
-/// In other words, interactions are allowed between two filter iff. the following condition is met:
+/// In other words, interactions are allowed between two filter iff. the following condition is met
+/// for [`InteractionTestMode::And`]:
 /// ```ignore
-/// (self.memberships & rhs.filter) != 0 && (rhs.memberships & self.filter) != 0
+/// (self.memberships.bits() & rhs.filter.bits()) != 0 && (rhs.memberships.bits() & self.filter.bits()) != 0
+/// ```
+/// or for [`InteractionTestMode::Or`]:
+/// ```ignore
+/// (self.memberships.bits() & rhs.filter.bits()) != 0 || (rhs.memberships.bits() & self.filter.bits()) != 0
 /// ```
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
@@ -23,25 +28,45 @@ pub struct InteractionGroups {
     pub memberships: Group,
     /// Groups filter.
     pub filter: Group,
+    /// Interaction test mode
+    ///
+    /// In case of different test modes between two [`InteractionGroups`], [`InteractionTestMode::And`] is given priority.
+    pub test_mode: InteractionTestMode,
+}
+
+#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, Default)]
+/// Specifies which method should be used to test interactions.
+///
+/// In case of different test modes between two [`InteractionGroups`], [`InteractionTestMode::And`] is given priority.
+pub enum InteractionTestMode {
+    /// Use [`InteractionGroups::test_and`].
+    #[default]
+    And,
+    /// Use [`InteractionGroups::test_or`], iff. the `rhs` is also [`InteractionTestMode::Or`].
+    ///
+    /// If the `rhs` is not [`InteractionTestMode::Or`], use [`InteractionGroups::test_and`].
+    Or,
 }
 
 impl InteractionGroups {
     /// Initializes with the given interaction groups and interaction mask.
-    pub const fn new(memberships: Group, filter: Group) -> Self {
+    pub const fn new(memberships: Group, filter: Group, test_mode: InteractionTestMode) -> Self {
         Self {
             memberships,
             filter,
+            test_mode,
         }
     }
 
     /// Allow interaction with everything.
     pub const fn all() -> Self {
-        Self::new(Group::ALL, Group::ALL)
+        Self::new(Group::ALL, Group::ALL, InteractionTestMode::And)
     }
 
     /// Prevent all interactions.
     pub const fn none() -> Self {
-        Self::new(Group::NONE, Group::NONE)
+        Self::new(Group::NONE, Group::NONE, InteractionTestMode::And)
     }
 
     /// Sets the group this filter is part of.
@@ -59,21 +84,42 @@ impl InteractionGroups {
     /// Check if interactions should be allowed based on the interaction memberships and filter.
     ///
     /// An interaction is allowed iff. the memberships of `self` contain at least one bit set to 1 in common
-    /// with the filter of `rhs`, and vice-versa.
+    /// with the filter of `rhs`, **and** vice-versa.
     #[inline]
-    pub const fn test(self, rhs: Self) -> bool {
-        // NOTE: since const ops is not stable, we have to convert `Group` into u32
-        // to use & operator in const context.
+    pub const fn test_and(self, rhs: Self) -> bool {
         (self.memberships.bits() & rhs.filter.bits()) != 0
             && (rhs.memberships.bits() & self.filter.bits()) != 0
     }
+
+    /// Check if interactions should be allowed based on the interaction memberships and filter.
+    ///
+    /// An interaction is allowed iff. the groups of `self` contain at least one bit set to 1 in common
+    /// with the mask of `rhs`, **or** vice-versa.
+    #[inline]
+    pub const fn test_or(self, rhs: Self) -> bool {
+        (self.memberships.bits() & rhs.filter.bits()) != 0
+            || (rhs.memberships.bits() & self.filter.bits()) != 0
+    }
+
+    /// Check if interactions should be allowed based on the interaction memberships and filter.
+    ///
+    /// See [`InteractionTestMode`] for more info.
+    #[inline]
+    pub const fn test(self, rhs: Self) -> bool {
+        match (self.test_mode, rhs.test_mode) {
+            (InteractionTestMode::And, _) => self.test_and(rhs),
+            (InteractionTestMode::Or, InteractionTestMode::And) => self.test_and(rhs),
+            (InteractionTestMode::Or, InteractionTestMode::Or) => self.test_or(rhs),
+        }
+    }
 }
 
 impl Default for InteractionGroups {
     fn default() -> Self {
         Self {
             memberships: Group::GROUP_1,
             filter: Group::ALL,
+            test_mode: InteractionTestMode::And,
         }
     }
 }

src/geometry/mod.rs

@@ -11,7 +11,7 @@ pub use self::contact_pair::{
 pub use self::interaction_graph::{
     ColliderGraphIndex, InteractionGraph, RigidBodyGraphIndex, TemporaryInteractionIndex,
 };
-pub use self::interaction_groups::{Group, InteractionGroups};
+pub use self::interaction_groups::{Group, InteractionGroups, InteractionTestMode};
 pub use self::mesh_converter::{MeshConverter, MeshConverterError};
 pub use self::narrow_phase::NarrowPhase;