Allow several rules for combining friction/restitution coefficients.

src/dynamics/coefficient_combine_rule.rs

@@ -0,0 +1,34 @@
+use crate::math::Real;
+
+/// Rules used to combine two coefficients.
+///
+/// This is used to determine the effective restitution and
+/// friction coefficients for a contact between two colliders.
+/// Each collider has its combination rule of type
+/// `CoefficientCombineRule`. And the rule
+/// actually used is given by `max(first_combine_rule as usize, second_combine_rule as usize)`.
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+pub enum CoefficientCombineRule {
+    /// The two coefficients are averaged.
+    Average = 0,
+    /// The smallest coefficient is chosen.
+    Min,
+    /// The two coefficients are multiplied.
+    Multiply,
+    /// The greatest coefficient is chosen.
+    Max,
+}
+
+impl CoefficientCombineRule {
+    pub(crate) fn combine(coeff1: Real, coeff2: Real, rule_value1: u8, rule_value2: u8) -> Real {
+        let effective_rule = rule_value1.max(rule_value2);
+
+        match effective_rule {
+            0 => (coeff1 + coeff1) / 2.0,
+            1 => coeff1.min(coeff2),
+            2 => coeff1 * coeff2,
+            _ => coeff1.max(coeff2),
+        }
+    }
+}

src/dynamics/mod.rs

@@ -11,6 +11,7 @@ pub use self::rigid_body::{ActivationStatus, BodyStatus, RigidBody, RigidBodyBui
 pub use self::rigid_body_set::{BodyPair, RigidBodyHandle, RigidBodySet};
 pub use cdl::mass_properties::MassProperties;
 // #[cfg(not(feature = "parallel"))]
+pub use self::coefficient_combine_rule::CoefficientCombineRule;
 pub(crate) use self::joint::JointGraphEdge;
 pub(crate) use self::rigid_body::RigidBodyChanges;
 #[cfg(not(feature = "parallel"))]
@@ -18,6 +19,7 @@ pub(crate) use self::solver::IslandSolver;
 #[cfg(feature = "parallel")]
 pub(crate) use self::solver::ParallelIslandSolver;
 
+mod coefficient_combine_rule;
 mod integration_parameters;
 mod joint;
 mod rigid_body;

src/dynamics/rigid_body.rs

@@ -62,8 +62,10 @@ pub struct RigidBody {
     pub(crate) mass_properties: MassProperties,
     /// The world-space center of mass of the rigid-body.
     pub world_com: Point<Real>,
+    /// The inverse mass taking into account translation locking.
     pub effective_inv_mass: Real,
-    /// The square-root of the inverse angular inertia tensor of the rigid-body.
+    /// The square-root of the world-space inverse angular inertia tensor of the rigid-body,
+    /// taking into account rotation locking.
     pub effective_world_inv_inertia_sqrt: AngularInertia<Real>,
     /// The linear velocity of the rigid-body.
     pub(crate) linvel: Vector<Real>,

src/geometry/collider.rs

@@ -1,309 +1,44 @@
-use crate::dynamics::{MassProperties, RigidBodyHandle};
+use crate::dynamics::{CoefficientCombineRule, MassProperties, RigidBodyHandle};
-use crate::geometry::InteractionGroups;
+use crate::geometry::{ColliderShape, InteractionGroups};
 use crate::math::{AngVector, Isometry, Point, Real, Rotation, Vector};
 use cdl::bounding_volume::AABB;
-use cdl::shape::{
+use cdl::shape::Shape;
-    Ball, Capsule, Compound, Cuboid, HalfSpace, HeightField, RoundCuboid, RoundShape,
-    RoundTriangle, Segment, Shape, ShapeType, TriMesh, Triangle,
-};
-#[cfg(feature = "dim3")]
-use cdl::shape::{
-    Cone, ConvexPolyhedron, Cylinder, RoundCone, RoundConvexPolyhedron, RoundCylinder,
-};
 #[cfg(feature = "dim2")]
 use cdl::shape::{ConvexPolygon, RoundConvexPolygon};
-use std::ops::Deref;
-use std::sync::Arc;
 
-// TODO: move this to its own file.
+bitflags::bitflags! {
-/// The shape of a collider.
+    #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
-#[derive(Clone)]
+    /// Flags affecting the behavior of the constraints solver for a given contact manifold.
-pub struct ColliderShape(pub Arc<dyn Shape>);
+    pub(crate) struct ColliderFlags: u8 {
-
+        const SENSOR = 1 << 0;
-impl Deref for ColliderShape {
+        const FRICTION_COMBINE_RULE_01 = 1 << 1;
-    type Target = dyn Shape;
+        const FRICTION_COMBINE_RULE_10 = 1 << 2;
-    fn deref(&self) -> &dyn Shape {
+        const RESTITUTION_COMBINE_RULE_01 = 1 << 3;
-        &*self.0
+        const RESTITUTION_COMBINE_RULE_10 = 1 << 4;
     }
 }
 
-impl ColliderShape {
+impl ColliderFlags {
-    /// Initialize a compound shape defined by its subshapes.
+    pub fn is_sensor(self) -> bool {
-    pub fn compound(shapes: Vec<(Isometry<Real>, ColliderShape)>) -> Self {
+        self.contains(ColliderFlags::SENSOR)
-        let raw_shapes = shapes.into_iter().map(|s| (s.0, s.1 .0)).collect();
-        let compound = Compound::new(raw_shapes);
-        ColliderShape(Arc::new(compound))
     }
 
-    /// Initialize a ball shape defined by its radius.
+    pub fn friction_combine_rule_value(self) -> u8 {
-    pub fn ball(radius: Real) -> Self {
+        (self.bits & 0b0000_0110) >> 1
-        ColliderShape(Arc::new(Ball::new(radius)))
     }
 
-    /// Initialize a cylindrical shape defined by its half-height
+    pub fn restitution_combine_rule_value(self) -> u8 {
-    /// (along along the y axis) and its radius.
+        (self.bits & 0b0001_1000) >> 3
-    #[cfg(feature = "dim3")]
-    pub fn cylinder(half_height: Real, radius: Real) -> Self {
-        ColliderShape(Arc::new(Cylinder::new(half_height, radius)))
     }
 
-    /// Initialize a rounded cylindrical shape defined by its half-height
+    pub fn with_friction_combine_rule(mut self, rule: CoefficientCombineRule) -> Self {
-    /// (along along the y axis), its radius, and its roundedness (the
+        self.bits = (self.bits & !0b0000_0110) | ((rule as u8) << 1);
-    /// radius of the sphere used for dilating the cylinder).
+        self
-    #[cfg(feature = "dim3")]
-    pub fn round_cylinder(half_height: Real, radius: Real, border_radius: Real) -> Self {
-        ColliderShape(Arc::new(RoundShape {
-            base_shape: Cylinder::new(half_height, radius),
-            border_radius,
-        }))
     }
 
-    /// Initialize a rounded cone shape defined by its half-height
+    pub fn with_restitution_combine_rule(mut self, rule: CoefficientCombineRule) -> Self {
-    /// (along along the y axis), its radius, and its roundedness (the
+        self.bits = (self.bits & !0b0001_1000) | ((rule as u8) << 3);
-    /// radius of the sphere used for dilating the cylinder).
+        self
-    #[cfg(feature = "dim3")]
-    pub fn round_cone(half_height: Real, radius: Real, border_radius: Real) -> Self {
-        ColliderShape(Arc::new(RoundShape {
-            base_shape: Cone::new(half_height, radius),
-            border_radius,
-        }))
-    }
-
-    /// Initialize a cone shape defined by its half-height
-    /// (along along the y axis) and its basis radius.
-    #[cfg(feature = "dim3")]
-    pub fn cone(half_height: Real, radius: Real) -> Self {
-        ColliderShape(Arc::new(Cone::new(half_height, radius)))
-    }
-
-    /// Initialize a cuboid shape defined by its half-extents.
-    #[cfg(feature = "dim2")]
-    pub fn cuboid(hx: Real, hy: Real) -> Self {
-        ColliderShape(Arc::new(Cuboid::new(Vector::new(hx, hy))))
-    }
-
-    /// Initialize a round cuboid shape defined by its half-extents and border radius.
-    #[cfg(feature = "dim2")]
-    pub fn round_cuboid(hx: Real, hy: Real, border_radius: Real) -> Self {
-        ColliderShape(Arc::new(RoundShape {
-            base_shape: Cuboid::new(Vector::new(hx, hy)),
-            border_radius,
-        }))
-    }
-
-    /// Initialize a cuboid shape defined by its half-extents.
-    #[cfg(feature = "dim3")]
-    pub fn cuboid(hx: Real, hy: Real, hz: Real) -> Self {
-        ColliderShape(Arc::new(Cuboid::new(Vector::new(hx, hy, hz))))
-    }
-
-    /// Initialize a round cuboid shape defined by its half-extents and border radius.
-    #[cfg(feature = "dim3")]
-    pub fn round_cuboid(hx: Real, hy: Real, hz: Real, border_radius: Real) -> Self {
-        ColliderShape(Arc::new(RoundShape {
-            base_shape: Cuboid::new(Vector::new(hx, hy, hz)),
-            border_radius,
-        }))
-    }
-
-    /// Initialize a capsule shape from its endpoints and radius.
-    pub fn capsule(a: Point<Real>, b: Point<Real>, radius: Real) -> Self {
-        ColliderShape(Arc::new(Capsule::new(a, b, radius)))
-    }
-
-    /// Initialize a segment shape from its endpoints.
-    pub fn segment(a: Point<Real>, b: Point<Real>) -> Self {
-        ColliderShape(Arc::new(Segment::new(a, b)))
-    }
-
-    /// Initializes a triangle shape.
-    pub fn triangle(a: Point<Real>, b: Point<Real>, c: Point<Real>) -> Self {
-        ColliderShape(Arc::new(Triangle::new(a, b, c)))
-    }
-
-    /// Initializes a triangle mesh shape defined by its vertex and index buffers.
-    pub fn trimesh(vertices: Vec<Point<Real>>, indices: Vec<[u32; 3]>) -> Self {
-        ColliderShape(Arc::new(TriMesh::new(vertices, indices)))
-    }
-
-    pub fn convex_hull(points: &[Point<Real>]) -> Option<Self> {
-        #[cfg(feature = "dim2")]
-        return ConvexPolygon::from_convex_hull(points).map(|ch| ColliderShape(Arc::new(ch)));
-        #[cfg(feature = "dim3")]
-        return ConvexPolyhedron::from_convex_hull(points).map(|ch| ColliderShape(Arc::new(ch)));
-    }
-
-    #[cfg(feature = "dim2")]
-    pub fn convex_polyline(points: Vec<Point<Real>>) -> Option<Self> {
-        ConvexPolygon::from_convex_polyline(points).map(|ch| ColliderShape(Arc::new(ch)))
-    }
-
-    #[cfg(feature = "dim3")]
-    pub fn convex_mesh(points: Vec<Point<Real>>, indices: &[[u32; 3]]) -> Option<Self> {
-        ConvexPolyhedron::from_convex_mesh(points, indices).map(|ch| ColliderShape(Arc::new(ch)))
-    }
-
-    pub fn round_convex_hull(points: &[Point<Real>], border_radius: Real) -> Option<Self> {
-        #[cfg(feature = "dim2")]
-        return ConvexPolygon::from_convex_hull(points).map(|ch| {
-            ColliderShape(Arc::new(RoundShape {
-                base_shape: ch,
-                border_radius,
-            }))
-        });
-        #[cfg(feature = "dim3")]
-        return ConvexPolyhedron::from_convex_hull(points).map(|ch| {
-            ColliderShape(Arc::new(RoundShape {
-                base_shape: ch,
-                border_radius,
-            }))
-        });
-    }
-
-    #[cfg(feature = "dim2")]
-    pub fn round_convex_polyline(points: Vec<Point<Real>>, border_radius: Real) -> Option<Self> {
-        ConvexPolygon::from_convex_polyline(points).map(|ch| {
-            ColliderShape(Arc::new(RoundShape {
-                base_shape: ch,
-                border_radius,
-            }))
-        })
-    }
-
-    #[cfg(feature = "dim3")]
-    pub fn round_convex_mesh(
-        points: Vec<Point<Real>>,
-        indices: &[[u32; 3]],
-        border_radius: Real,
-    ) -> Option<Self> {
-        ConvexPolyhedron::from_convex_mesh(points, indices).map(|ch| {
-            ColliderShape(Arc::new(RoundShape {
-                base_shape: ch,
-                border_radius,
-            }))
-        })
-    }
-
-    /// Initializes an heightfield shape defined by its set of height and a scale
-    /// factor along each coordinate axis.
-    #[cfg(feature = "dim2")]
-    pub fn heightfield(heights: na::DVector<Real>, scale: Vector<Real>) -> Self {
-        ColliderShape(Arc::new(HeightField::new(heights, scale)))
-    }
-
-    /// Initializes an heightfield shape on the x-z plane defined by its set of height and a scale
-    /// factor along each coordinate axis.
-    #[cfg(feature = "dim3")]
-    pub fn heightfield(heights: na::DMatrix<Real>, scale: Vector<Real>) -> Self {
-        ColliderShape(Arc::new(HeightField::new(heights, scale)))
-    }
-}
-
-#[cfg(feature = "serde-serialize")]
-impl serde::Serialize for ColliderShape {
-    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    where
-        S: serde::Serializer,
-    {
-        use crate::serde::ser::SerializeStruct;
-
-        if let Some(ser) = self.0.as_serialize() {
-            let typ = self.0.shape_type();
-            let mut state = serializer.serialize_struct("ColliderShape", 2)?;
-            state.serialize_field("tag", &(typ as i32))?;
-            state.serialize_field("inner", ser)?;
-            state.end()
-        } else {
-            Err(serde::ser::Error::custom(
-                "Found a non-serializable custom shape.",
-            ))
-        }
-    }
-}
-
-#[cfg(feature = "serde-serialize")]
-impl<'de> serde::Deserialize<'de> for ColliderShape {
-    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-    where
-        D: serde::Deserializer<'de>,
-    {
-        struct Visitor {};
-        impl<'de> serde::de::Visitor<'de> for Visitor {
-            type Value = ColliderShape;
-            fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
-                write!(formatter, "one shape type tag and the inner shape data")
-            }
-
-            fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
-            where
-                A: serde::de::SeqAccess<'de>,
-            {
-                use num::cast::FromPrimitive;
-
-                let tag: i32 = seq
-                    .next_element()?
-                    .ok_or_else(|| serde::de::Error::invalid_length(0, &self))?;
-
-                fn deser<'de, A, S: Shape + serde::Deserialize<'de>>(
-                    seq: &mut A,
-                ) -> Result<Arc<dyn Shape>, A::Error>
-                where
-                    A: serde::de::SeqAccess<'de>,
-                {
-                    let shape: S = seq.next_element()?.ok_or_else(|| {
-                        serde::de::Error::custom("Failed to deserialize builtin shape.")
-                    })?;
-                    Ok(Arc::new(shape) as Arc<dyn Shape>)
-                }
-
-                let shape = match ShapeType::from_i32(tag) {
-                    Some(ShapeType::Ball) => deser::<A, Ball>(&mut seq)?,
-                    Some(ShapeType::Cuboid) => deser::<A, Cuboid>(&mut seq)?,
-                    Some(ShapeType::Capsule) => deser::<A, Capsule>(&mut seq)?,
-                    Some(ShapeType::Triangle) => deser::<A, Triangle>(&mut seq)?,
-                    Some(ShapeType::Segment) => deser::<A, Segment>(&mut seq)?,
-                    Some(ShapeType::TriMesh) => deser::<A, TriMesh>(&mut seq)?,
-                    Some(ShapeType::HeightField) => deser::<A, HeightField>(&mut seq)?,
-                    Some(ShapeType::HalfSpace) => deser::<A, HalfSpace>(&mut seq)?,
-                    Some(ShapeType::RoundCuboid) => deser::<A, RoundCuboid>(&mut seq)?,
-                    Some(ShapeType::RoundTriangle) => deser::<A, RoundTriangle>(&mut seq)?,
-                    #[cfg(feature = "dim2")]
-                    Some(ShapeType::ConvexPolygon) => deser::<A, ConvexPolygon>(&mut seq)?,
-                    #[cfg(feature = "dim2")]
-                    Some(ShapeType::RoundConvexPolygon) => {
-                        deser::<A, RoundConvexPolygon>(&mut seq)?
-                    }
-                    #[cfg(feature = "dim3")]
-                    Some(ShapeType::Cylinder) => deser::<A, Cylinder>(&mut seq)?,
-                    #[cfg(feature = "dim3")]
-                    Some(ShapeType::ConvexPolyhedron) => deser::<A, ConvexPolyhedron>(&mut seq)?,
-                    #[cfg(feature = "dim3")]
-                    Some(ShapeType::Cone) => deser::<A, Cone>(&mut seq)?,
-                    #[cfg(feature = "dim3")]
-                    Some(ShapeType::RoundCylinder) => deser::<A, RoundCylinder>(&mut seq)?,
-                    #[cfg(feature = "dim3")]
-                    Some(ShapeType::RoundCone) => deser::<A, RoundCone>(&mut seq)?,
-                    #[cfg(feature = "dim3")]
-                    Some(ShapeType::RoundConvexPolyhedron) => {
-                        deser::<A, RoundConvexPolyhedron>(&mut seq)?
-                    }
-                    Some(ShapeType::Compound) => {
-                        return Err(serde::de::Error::custom(
-                            "found invalid shape type to deserialize",
-                        ))
-                    }
-                    None => {
-                        return Err(serde::de::Error::custom(
-                            "found invalid shape type to deserialize",
-                        ))
-                    }
-                };
-
-                Ok(ColliderShape(shape))
-            }
-        }
-
-        deserializer.deserialize_struct("ColliderShape", &["tag", "inner"], Visitor {})
     }
 }
 
@@ -315,7 +50,7 @@ impl<'de> serde::Deserialize<'de> for ColliderShape {
 pub struct Collider {
     shape: ColliderShape,
     density: Real,
-    is_sensor: bool,
+    pub(crate) flags: ColliderFlags,
     pub(crate) parent: RigidBodyHandle,
     pub(crate) delta: Isometry<Real>,
     pub(crate) position: Isometry<Real>,
@@ -344,7 +79,7 @@ impl Collider {
 
     /// Is this collider a sensor?
     pub fn is_sensor(&self) -> bool {
-        self.is_sensor
+        self.flags.is_sensor()
     }
 
     #[doc(hidden)]
@@ -415,8 +150,12 @@ pub struct ColliderBuilder {
     density: Option<Real>,
     /// The friction coefficient of the collider to be built.
     pub friction: Real,
+    /// The rule used to combine two friction coefficients.
+    pub friction_combine_rule: CoefficientCombineRule,
     /// The restitution coefficient of the collider to be built.
     pub restitution: Real,
+    /// The rule used to combine two restitution coefficients.
+    pub restitution_combine_rule: CoefficientCombineRule,
     /// The position of this collider relative to the local frame of the rigid-body it is attached to.
     pub delta: Isometry<Real>,
     /// Is this collider a sensor?
@@ -442,6 +181,8 @@ impl ColliderBuilder {
             user_data: 0,
             collision_groups: InteractionGroups::all(),
             solver_groups: InteractionGroups::all(),
+            friction_combine_rule: CoefficientCombineRule::Average,
+            restitution_combine_rule: CoefficientCombineRule::Average,
         }
     }
 
@@ -645,12 +386,24 @@ impl ColliderBuilder {
         self
     }
 
+    /// Sets the rule to be used to combine two friction coefficients in a contact.
+    pub fn friction_combine_rule(mut self, rule: CoefficientCombineRule) -> Self {
+        self.friction_combine_rule = rule;
+        self
+    }
+
     /// Sets the restitution coefficient of the collider this builder will build.
     pub fn restitution(mut self, restitution: Real) -> Self {
         self.restitution = restitution;
         self
     }
 
+    /// Sets the rule to be used to combine two restitution coefficients in a contact.
+    pub fn restitution_combine_rule(mut self, rule: CoefficientCombineRule) -> Self {
+        self.restitution_combine_rule = rule;
+        self
+    }
+
     /// Sets the density of the collider this builder will build.
     pub fn density(mut self, density: Real) -> Self {
         self.density = Some(density);
@@ -700,6 +453,11 @@ impl ColliderBuilder {
     /// Builds a new collider attached to the given rigid-body.
     pub fn build(&self) -> Collider {
         let density = self.get_density();
+        let mut flags = ColliderFlags::empty();
+        flags.set(ColliderFlags::SENSOR, self.is_sensor);
+        flags = flags
+            .with_friction_combine_rule(self.friction_combine_rule)
+            .with_restitution_combine_rule(self.restitution_combine_rule);
 
         Collider {
             shape: self.shape.clone(),
@@ -707,7 +465,7 @@ impl ColliderBuilder {
             friction: self.friction,
             restitution: self.restitution,
             delta: self.delta,
-            is_sensor: self.is_sensor,
+            flags,
             parent: RigidBodyHandle::invalid(),
             position: Isometry::identity(),
             predicted_position: Isometry::identity(),

src/geometry/collider_shape.rs

@@ -0,0 +1,304 @@
+use crate::math::{Isometry, Point, Real, Vector};
+use cdl::shape::{
+    Ball, Capsule, Compound, Cuboid, HalfSpace, HeightField, RoundCuboid, RoundShape,
+    RoundTriangle, Segment, Shape, ShapeType, TriMesh, Triangle,
+};
+#[cfg(feature = "dim3")]
+use cdl::shape::{
+    Cone, ConvexPolyhedron, Cylinder, RoundCone, RoundConvexPolyhedron, RoundCylinder,
+};
+#[cfg(feature = "dim2")]
+use cdl::shape::{ConvexPolygon, RoundConvexPolygon};
+use std::ops::Deref;
+use std::sync::Arc;
+
+/// The shape of a collider.
+#[derive(Clone)]
+pub struct ColliderShape(pub Arc<dyn Shape>);
+
+impl Deref for ColliderShape {
+    type Target = dyn Shape;
+    fn deref(&self) -> &dyn Shape {
+        &*self.0
+    }
+}
+
+impl ColliderShape {
+    /// Initialize a compound shape defined by its subshapes.
+    pub fn compound(shapes: Vec<(Isometry<Real>, ColliderShape)>) -> Self {
+        let raw_shapes = shapes.into_iter().map(|s| (s.0, s.1 .0)).collect();
+        let compound = Compound::new(raw_shapes);
+        ColliderShape(Arc::new(compound))
+    }
+
+    /// Initialize a ball shape defined by its radius.
+    pub fn ball(radius: Real) -> Self {
+        ColliderShape(Arc::new(Ball::new(radius)))
+    }
+
+    /// Initialize a cylindrical shape defined by its half-height
+    /// (along along the y axis) and its radius.
+    #[cfg(feature = "dim3")]
+    pub fn cylinder(half_height: Real, radius: Real) -> Self {
+        ColliderShape(Arc::new(Cylinder::new(half_height, radius)))
+    }
+
+    /// Initialize a rounded cylindrical shape defined by its half-height
+    /// (along along the y axis), its radius, and its roundedness (the
+    /// radius of the sphere used for dilating the cylinder).
+    #[cfg(feature = "dim3")]
+    pub fn round_cylinder(half_height: Real, radius: Real, border_radius: Real) -> Self {
+        ColliderShape(Arc::new(RoundShape {
+            base_shape: Cylinder::new(half_height, radius),
+            border_radius,
+        }))
+    }
+
+    /// Initialize a rounded cone shape defined by its half-height
+    /// (along along the y axis), its radius, and its roundedness (the
+    /// radius of the sphere used for dilating the cylinder).
+    #[cfg(feature = "dim3")]
+    pub fn round_cone(half_height: Real, radius: Real, border_radius: Real) -> Self {
+        ColliderShape(Arc::new(RoundShape {
+            base_shape: Cone::new(half_height, radius),
+            border_radius,
+        }))
+    }
+
+    /// Initialize a cone shape defined by its half-height
+    /// (along along the y axis) and its basis radius.
+    #[cfg(feature = "dim3")]
+    pub fn cone(half_height: Real, radius: Real) -> Self {
+        ColliderShape(Arc::new(Cone::new(half_height, radius)))
+    }
+
+    /// Initialize a cuboid shape defined by its half-extents.
+    #[cfg(feature = "dim2")]
+    pub fn cuboid(hx: Real, hy: Real) -> Self {
+        ColliderShape(Arc::new(Cuboid::new(Vector::new(hx, hy))))
+    }
+
+    /// Initialize a round cuboid shape defined by its half-extents and border radius.
+    #[cfg(feature = "dim2")]
+    pub fn round_cuboid(hx: Real, hy: Real, border_radius: Real) -> Self {
+        ColliderShape(Arc::new(RoundShape {
+            base_shape: Cuboid::new(Vector::new(hx, hy)),
+            border_radius,
+        }))
+    }
+
+    /// Initialize a cuboid shape defined by its half-extents.
+    #[cfg(feature = "dim3")]
+    pub fn cuboid(hx: Real, hy: Real, hz: Real) -> Self {
+        ColliderShape(Arc::new(Cuboid::new(Vector::new(hx, hy, hz))))
+    }
+
+    /// Initialize a round cuboid shape defined by its half-extents and border radius.
+    #[cfg(feature = "dim3")]
+    pub fn round_cuboid(hx: Real, hy: Real, hz: Real, border_radius: Real) -> Self {
+        ColliderShape(Arc::new(RoundShape {
+            base_shape: Cuboid::new(Vector::new(hx, hy, hz)),
+            border_radius,
+        }))
+    }
+
+    /// Initialize a capsule shape from its endpoints and radius.
+    pub fn capsule(a: Point<Real>, b: Point<Real>, radius: Real) -> Self {
+        ColliderShape(Arc::new(Capsule::new(a, b, radius)))
+    }
+
+    /// Initialize a segment shape from its endpoints.
+    pub fn segment(a: Point<Real>, b: Point<Real>) -> Self {
+        ColliderShape(Arc::new(Segment::new(a, b)))
+    }
+
+    /// Initializes a triangle shape.
+    pub fn triangle(a: Point<Real>, b: Point<Real>, c: Point<Real>) -> Self {
+        ColliderShape(Arc::new(Triangle::new(a, b, c)))
+    }
+
+    /// Initializes a triangle mesh shape defined by its vertex and index buffers.
+    pub fn trimesh(vertices: Vec<Point<Real>>, indices: Vec<[u32; 3]>) -> Self {
+        ColliderShape(Arc::new(TriMesh::new(vertices, indices)))
+    }
+
+    pub fn convex_hull(points: &[Point<Real>]) -> Option<Self> {
+        #[cfg(feature = "dim2")]
+        return ConvexPolygon::from_convex_hull(points).map(|ch| ColliderShape(Arc::new(ch)));
+        #[cfg(feature = "dim3")]
+        return ConvexPolyhedron::from_convex_hull(points).map(|ch| ColliderShape(Arc::new(ch)));
+    }
+
+    #[cfg(feature = "dim2")]
+    pub fn convex_polyline(points: Vec<Point<Real>>) -> Option<Self> {
+        ConvexPolygon::from_convex_polyline(points).map(|ch| ColliderShape(Arc::new(ch)))
+    }
+
+    #[cfg(feature = "dim3")]
+    pub fn convex_mesh(points: Vec<Point<Real>>, indices: &[[u32; 3]]) -> Option<Self> {
+        ConvexPolyhedron::from_convex_mesh(points, indices).map(|ch| ColliderShape(Arc::new(ch)))
+    }
+
+    pub fn round_convex_hull(points: &[Point<Real>], border_radius: Real) -> Option<Self> {
+        #[cfg(feature = "dim2")]
+        return ConvexPolygon::from_convex_hull(points).map(|ch| {
+            ColliderShape(Arc::new(RoundShape {
+                base_shape: ch,
+                border_radius,
+            }))
+        });
+        #[cfg(feature = "dim3")]
+        return ConvexPolyhedron::from_convex_hull(points).map(|ch| {
+            ColliderShape(Arc::new(RoundShape {
+                base_shape: ch,
+                border_radius,
+            }))
+        });
+    }
+
+    #[cfg(feature = "dim2")]
+    pub fn round_convex_polyline(points: Vec<Point<Real>>, border_radius: Real) -> Option<Self> {
+        ConvexPolygon::from_convex_polyline(points).map(|ch| {
+            ColliderShape(Arc::new(RoundShape {
+                base_shape: ch,
+                border_radius,
+            }))
+        })
+    }
+
+    #[cfg(feature = "dim3")]
+    pub fn round_convex_mesh(
+        points: Vec<Point<Real>>,
+        indices: &[[u32; 3]],
+        border_radius: Real,
+    ) -> Option<Self> {
+        ConvexPolyhedron::from_convex_mesh(points, indices).map(|ch| {
+            ColliderShape(Arc::new(RoundShape {
+                base_shape: ch,
+                border_radius,
+            }))
+        })
+    }
+
+    /// Initializes an heightfield shape defined by its set of height and a scale
+    /// factor along each coordinate axis.
+    #[cfg(feature = "dim2")]
+    pub fn heightfield(heights: na::DVector<Real>, scale: Vector<Real>) -> Self {
+        ColliderShape(Arc::new(HeightField::new(heights, scale)))
+    }
+
+    /// Initializes an heightfield shape on the x-z plane defined by its set of height and a scale
+    /// factor along each coordinate axis.
+    #[cfg(feature = "dim3")]
+    pub fn heightfield(heights: na::DMatrix<Real>, scale: Vector<Real>) -> Self {
+        ColliderShape(Arc::new(HeightField::new(heights, scale)))
+    }
+}
+
+#[cfg(feature = "serde-serialize")]
+impl serde::Serialize for ColliderShape {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        use crate::serde::ser::SerializeStruct;
+
+        if let Some(ser) = self.0.as_serialize() {
+            let typ = self.0.shape_type();
+            let mut state = serializer.serialize_struct("ColliderShape", 2)?;
+            state.serialize_field("tag", &(typ as i32))?;
+            state.serialize_field("inner", ser)?;
+            state.end()
+        } else {
+            Err(serde::ser::Error::custom(
+                "Found a non-serializable custom shape.",
+            ))
+        }
+    }
+}
+
+#[cfg(feature = "serde-serialize")]
+impl<'de> serde::Deserialize<'de> for ColliderShape {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        struct Visitor {};
+        impl<'de> serde::de::Visitor<'de> for Visitor {
+            type Value = ColliderShape;
+            fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+                write!(formatter, "one shape type tag and the inner shape data")
+            }
+
+            fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
+            where
+                A: serde::de::SeqAccess<'de>,
+            {
+                use num::cast::FromPrimitive;
+
+                let tag: i32 = seq
+                    .next_element()?
+                    .ok_or_else(|| serde::de::Error::invalid_length(0, &self))?;
+
+                fn deser<'de, A, S: Shape + serde::Deserialize<'de>>(
+                    seq: &mut A,
+                ) -> Result<Arc<dyn Shape>, A::Error>
+                where
+                    A: serde::de::SeqAccess<'de>,
+                {
+                    let shape: S = seq.next_element()?.ok_or_else(|| {
+                        serde::de::Error::custom("Failed to deserialize builtin shape.")
+                    })?;
+                    Ok(Arc::new(shape) as Arc<dyn Shape>)
+                }
+
+                let shape = match ShapeType::from_i32(tag) {
+                    Some(ShapeType::Ball) => deser::<A, Ball>(&mut seq)?,
+                    Some(ShapeType::Cuboid) => deser::<A, Cuboid>(&mut seq)?,
+                    Some(ShapeType::Capsule) => deser::<A, Capsule>(&mut seq)?,
+                    Some(ShapeType::Triangle) => deser::<A, Triangle>(&mut seq)?,
+                    Some(ShapeType::Segment) => deser::<A, Segment>(&mut seq)?,
+                    Some(ShapeType::TriMesh) => deser::<A, TriMesh>(&mut seq)?,
+                    Some(ShapeType::HeightField) => deser::<A, HeightField>(&mut seq)?,
+                    Some(ShapeType::HalfSpace) => deser::<A, HalfSpace>(&mut seq)?,
+                    Some(ShapeType::RoundCuboid) => deser::<A, RoundCuboid>(&mut seq)?,
+                    Some(ShapeType::RoundTriangle) => deser::<A, RoundTriangle>(&mut seq)?,
+                    #[cfg(feature = "dim2")]
+                    Some(ShapeType::ConvexPolygon) => deser::<A, ConvexPolygon>(&mut seq)?,
+                    #[cfg(feature = "dim2")]
+                    Some(ShapeType::RoundConvexPolygon) => {
+                        deser::<A, RoundConvexPolygon>(&mut seq)?
+                    }
+                    #[cfg(feature = "dim3")]
+                    Some(ShapeType::Cylinder) => deser::<A, Cylinder>(&mut seq)?,
+                    #[cfg(feature = "dim3")]
+                    Some(ShapeType::ConvexPolyhedron) => deser::<A, ConvexPolyhedron>(&mut seq)?,
+                    #[cfg(feature = "dim3")]
+                    Some(ShapeType::Cone) => deser::<A, Cone>(&mut seq)?,
+                    #[cfg(feature = "dim3")]
+                    Some(ShapeType::RoundCylinder) => deser::<A, RoundCylinder>(&mut seq)?,
+                    #[cfg(feature = "dim3")]
+                    Some(ShapeType::RoundCone) => deser::<A, RoundCone>(&mut seq)?,
+                    #[cfg(feature = "dim3")]
+                    Some(ShapeType::RoundConvexPolyhedron) => {
+                        deser::<A, RoundConvexPolyhedron>(&mut seq)?
+                    }
+                    Some(ShapeType::Compound) => {
+                        return Err(serde::de::Error::custom(
+                            "found invalid shape type to deserialize",
+                        ))
+                    }
+                    None => {
+                        return Err(serde::de::Error::custom(
+                            "found invalid shape type to deserialize",
+                        ))
+                    }
+                };
+
+                Ok(ColliderShape(shape))
+            }
+        }
+
+        deserializer.deserialize_struct("ColliderShape", &["tag", "inner"], Visitor {})
+    }
+}

src/geometry/mod.rs

@@ -1,13 +1,15 @@
 //! Structures related to geometry: colliders, shapes, etc.
 
 pub use self::broad_phase_multi_sap::BroadPhase;
-pub use self::collider::{Collider, ColliderBuilder, ColliderShape};
+pub use self::collider::{Collider, ColliderBuilder};
 pub use self::collider_set::{ColliderHandle, ColliderSet};
+pub use self::collider_shape::ColliderShape;
 pub use self::contact_pair::{ContactData, ContactManifoldData};
 pub use self::contact_pair::{ContactPair, SolverContact, SolverFlags};
 pub use self::interaction_graph::{
     ColliderGraphIndex, InteractionGraph, RigidBodyGraphIndex, TemporaryInteractionIndex,
 };
+pub use self::interaction_groups::InteractionGroups;
 pub use self::narrow_phase::NarrowPhase;
 pub use self::pair_filter::{ContactPairFilter, PairFilterContext, ProximityPairFilter};
 
@@ -81,7 +83,6 @@ impl IntersectionEvent {
 
 pub(crate) use self::broad_phase_multi_sap::{BroadPhasePairEvent, ColliderPair};
 pub(crate) use self::collider_set::RemovedCollider;
-pub use self::interaction_groups::InteractionGroups;
 pub(crate) use self::narrow_phase::ContactManifoldIndex;
 pub(crate) use cdl::partitioning::SimdQuadTree;
 pub use cdl::shape::*;
@@ -98,6 +99,7 @@ pub(crate) fn default_query_dispatcher() -> std::sync::Arc<dyn cdl::query::Query
 mod broad_phase_multi_sap;
 mod collider;
 mod collider_set;
+mod collider_shape;
 mod contact_pair;
 mod interaction_graph;
 mod interaction_groups;

src/geometry/narrow_phase.rs

@@ -3,7 +3,7 @@ use rayon::prelude::*;
 
 use crate::data::pubsub::Subscription;
 use crate::data::Coarena;
-use crate::dynamics::{BodyPair, RigidBodySet};
+use crate::dynamics::{BodyPair, CoefficientCombineRule, RigidBodySet};
 use crate::geometry::{
     BroadPhasePairEvent, ColliderGraphIndex, ColliderHandle, ContactData, ContactEvent,
     ContactManifoldData, ContactPairFilter, IntersectionEvent, PairFilterContext,
@@ -522,6 +522,19 @@ impl NarrowPhase {
 
             let mut has_any_active_contact = false;
 
+            let friction = CoefficientCombineRule::combine(
+                co1.friction,
+                co2.friction,
+                co1.flags.friction_combine_rule_value(),
+                co2.flags.friction_combine_rule_value(),
+            );
+            let restitution = CoefficientCombineRule::combine(
+                co1.restitution,
+                co2.restitution,
+                co1.flags.restitution_combine_rule_value(),
+                co2.flags.restitution_combine_rule_value(),
+            );
+
             for manifold in &mut pair.manifolds {
                 let world_pos1 = manifold.subshape_pos1.prepend_to(co1.position());
                 manifold.data.solver_contacts.clear();
@@ -541,8 +554,8 @@ impl NarrowPhase {
                             point: world_pos1 * contact.local_p1
                                 + manifold.data.normal * contact.dist / 2.0,
                             dist: contact.dist,
-                            friction: (co1.friction + co2.friction) / 2.0,
+                            friction,
-                            restitution: (co1.restitution + co2.restitution) / 2.0,
+                            restitution,
                             surface_velocity: Vector::zeros(),
                             data: contact.data,
                         };