Implement multibody joints and the new solver

36 files changed, 1015 insertions, 232 deletions

diff --git a/examples3d/Cargo.toml b/examples3d/Cargo.toml
index 897c92b..bbab27e 100644
--- a/examples3d/Cargo.toml
+++ b/examples3d/Cargo.toml
@@ -2,7 +2,7 @@
 name    = "rapier-examples-3d"
 version = "0.1.0"
 authors = [ "Sébastien Crozet <developer@crozet.re>" ]
-edition = "2018"
+edition = "2021"
 default-run = "all_examples3"
 
 [features]
@@ -20,10 +20,10 @@ wasm-bindgen = "0.2"
 obj-rs = { version =  "0.6", default-features = false }
 
 [dependencies.rapier_testbed3d]
-path = "../build/rapier_testbed3d"
+path = "../crates/rapier_testbed3d"
 
 [dependencies.rapier3d]
-path = "../build/rapier3d"
+path = "../crates/rapier3d"
 
 [[bin]]
 name = "all_examples3"
diff --git a/examples3d/all_examples3.rs b/examples3d/all_examples3.rs
index a9e1456..0aad4c2 100644
--- a/examples3d/all_examples3.rs
+++ b/examples3d/all_examples3.rs
@@ -8,6 +8,7 @@ use inflector::Inflector;
 use rapier_testbed3d::{Testbed, TestbedApp};
 use std::cmp::Ordering;
 
+mod articulations3;
 mod ccd3;
 mod collision_groups3;
 mod compound3;
@@ -15,6 +16,7 @@ mod convex_decomposition3;
 mod convex_polyhedron3;
 mod damping3;
 mod debug_add_remove_collider3;
+mod debug_articulations3;
 mod debug_big_colliders3;
 mod debug_boxes3;
 mod debug_cylinder3;
@@ -29,7 +31,7 @@ mod debug_trimesh3;
 mod domino3;
 mod fountain3;
 mod heightfield3;
-mod joints3;
+// mod joints3;
 mod keva3;
 mod locked_rotations3;
 mod one_way_platforms3;
@@ -78,6 +80,10 @@ pub fn main() {
     let mut builders: Vec<(_, fn(&mut Testbed))> = vec![
         ("Fountain", fountain3::init_world),
         ("Primitives", primitives3::init_world),
+        (
+            "Multibody joints",
+            articulations3::init_world_with_articulations,
+        ),
         ("CCD", ccd3::init_world),
         ("Collision groups", collision_groups3::init_world),
         ("Compound", compound3::init_world),
@@ -86,7 +92,7 @@ pub fn main() {
         ("Damping", damping3::init_world),
         ("Domino", domino3::init_world),
         ("Heightfield", heightfield3::init_world),
-        ("Joints", joints3::init_world),
+        ("Impulse Joints", articulations3::init_world_with_joints),
         ("Locked rotations", locked_rotations3::init_world),
         ("One-way platforms", one_way_platforms3::init_world),
         ("Platform", platform3::init_world),
@@ -94,6 +100,7 @@ pub fn main() {
         ("Sensor", sensor3::init_world),
         ("TriMesh", trimesh3::init_world),
         ("Keva tower", keva3::init_world),
+        ("(Debug) multibody_joints", debug_articulations3::init_world),
         (
             "(Debug) add/rm collider",
             debug_add_remove_collider3::init_world,
diff --git a/examples3d/articulations3.rs b/examples3d/articulations3.rs
new file mode 100644
index 0000000..0c87c41
--- /dev/null
+++ b/examples3d/articulations3.rs
@@ -0,0 +1,678 @@
+use rapier3d::prelude::*;
+use rapier_testbed3d::Testbed;
+
+fn create_prismatic_joints(
+    bodies: &mut RigidBodySet,
+    colliders: &mut ColliderSet,
+    impulse_joints: &mut ImpulseJointSet,
+    multibody_joints: &mut MultibodyJointSet,
+    origin: Point<f32>,
+    num: usize,
+    use_articulations: bool,
+) {
+    let rad = 0.4;
+    let shift = 2.0;
+
+    let ground = RigidBodyBuilder::new_static()
+        .translation(vector![origin.x, origin.y, origin.z])
+        .build();
+    let mut curr_parent = bodies.insert(ground);
+    let collider = ColliderBuilder::cuboid(rad, rad, rad).build();
+    colliders.insert_with_parent(collider, curr_parent, bodies);
+
+    for i in 0..num {
+        let z = origin.z + (i + 1) as f32 * shift;
+        let rigid_body = RigidBodyBuilder::new_dynamic()
+            .translation(vector![origin.x, origin.y, z])
+            .build();
+        let curr_child = bodies.insert(rigid_body);
+        let collider = ColliderBuilder::cuboid(rad, rad, rad).build();
+        colliders.insert_with_parent(collider, curr_child, bodies);
+
+        let axis = if i % 2 == 0 {
+            UnitVector::new_normalize(vector![1.0f32, 1.0, 0.0])
+        } else {
+            UnitVector::new_normalize(vector![-1.0f32, 1.0, 0.0])
+        };
+
+        let prism = PrismaticJoint::new(axis)
+            .local_anchor1(point![0.0, 0.0, 0.0])
+            .local_anchor2(point![0.0, 0.0, -shift])
+            .limit_axis([-2.0, 2.0]);
+
+        if use_articulations {
+            multibody_joints.insert(curr_parent, curr_child, prism);
+        } else {
+            impulse_joints.insert(curr_parent, curr_child, prism);
+        }
+        curr_parent = curr_child;
+    }
+}
+
+fn create_actuated_prismatic_joints(
+    bodies: &mut RigidBodySet,
+    colliders: &mut ColliderSet,
+    impulse_joints: &mut ImpulseJointSet,
+    multibody_joints: &mut MultibodyJointSet,
+    origin: Point<f32>,
+    num: usize,
+    use_articulations: bool,
+) {
+    let rad = 0.4;
+    let shift = 2.0;
+
+    let ground = RigidBodyBuilder::new_static()
+        .translation(vector![origin.x, origin.y, origin.z])
+        .build();
+    let mut curr_parent = bodies.insert(ground);
+    let collider = ColliderBuilder::cuboid(rad, rad, rad).build();
+    colliders.insert_with_parent(collider, curr_parent, bodies);
+
+    for i in 0..num {
+        let z = origin.z + (i + 1) as f32 * shift;
+        let rigid_body = RigidBodyBuilder::new_dynamic()
+            .translation(vector![origin.x, origin.y, z])
+            .build();
+        let curr_child = bodies.insert(rigid_body);
+        let collider = ColliderBuilder::cuboid(rad, rad, rad).build();
+        colliders.insert_with_parent(collider, curr_child, bodies);
+
+        let axis = if i % 2 == 0 {
+            UnitVector::new_normalize(vector![1.0, 1.0, 0.0])
+        } else {
+            UnitVector::new_normalize(vector![-1.0, 1.0, 0.0])
+        };
+
+        let mut prism = PrismaticJoint::new(axis)
+            .local_anchor1(point![0.0, 0.0, 0.0])
+            .local_anchor2(point![0.0, 0.0, -shift]);
+
+        if i == 1 {
+            prism = prism
+                .limit_axis([-Real::MAX, 5.0])
+                .motor_velocity(1.0, 1.0)
+                // We set a max impulse so that the motor doesn't fight
+                // the limits with large forces.
+                .motor_max_impulse(1.0);
+        } else if i > 1 {
+            prism = prism.motor_position(2.0, 0.01, 1.0);
+        } else {
+            prism = prism
+                .motor_velocity(1.0, 1.0)
+                // We set a max impulse so that the motor doesn't fight
+                // the limits with large forces.
+                .motor_max_impulse(0.7)
+                .limit_axis([-2.0, 5.0]);
+        }
+
+        if use_articulations {
+            multibody_joints.insert(curr_parent, curr_child, prism);
+        } else {
+            impulse_joints.insert(curr_parent, curr_child, prism);
+        }
+
+        curr_parent = curr_child;
+    }
+}
+
+fn create_revolute_joints(
+    bodies: &mut RigidBodySet,
+    colliders: &mut ColliderSet,
+    impulse_joints: &mut ImpulseJointSet,
+    multibody_joints: &mut MultibodyJointSet,
+    origin: Point<f32>,
+    num: usize,
+    use_articulations: bool,
+) {
+    let rad = 0.4;
+    let shift = 2.0;
+
+    let ground = RigidBodyBuilder::new_static()
+        .translation(vector![origin.x, origin.y, 0.0])
+        .build();
+    let mut curr_parent = bodies.insert(ground);
+    let collider = ColliderBuilder::cuboid(rad, rad, rad).build();
+    colliders.insert_with_parent(collider, curr_parent, bodies);
+
+    for i in 0..num {
+        // Create four bodies.
+        let z = origin.z + i as f32 * shift * 2.0 + shift;
+        let positions = [
+            Isometry::translation(origin.x, origin.y, z),
+            Isometry::translation(origin.x + shift, origin.y, z),
+            Isometry::translation(origin.x + shift, origin.y, z + shift),
+            Isometry::translation(origin.x, origin.y, z + shift),
+        ];
+
+        let mut handles = [curr_parent; 4];
+        for k in 0..4 {
+            let rigid_body = RigidBodyBuilder::new_dynamic()
+                .position(positions[k])
+                .build();
+            handles[k] = bodies.insert(rigid_body);
+            let collider = ColliderBuilder::cuboid(rad, rad, rad).build();
+            colliders.insert_with_parent(collider, handles[k], bodies);
+        }
+
+        // Setup four impulse_joints.
+        let x = Vector::x_axis();
+        let z = Vector::z_axis();
+        let revs = [
+            RevoluteJoint::new(z).local_anchor2(point![0.0, 0.0, -shift]),
+            RevoluteJoint::new(x).local_anchor2(point![-shift, 0.0, 0.0]),
+            RevoluteJoint::new(z).local_anchor2(point![0.0, 0.0, -shift]),
+            RevoluteJoint::new(x).local_anchor2(point![shift, 0.0, 0.0]),
+        ];
+
+        if use_articulations {
+            multibody_joints.insert(curr_parent, handles[0], revs[0]);
+            multibody_joints.insert(handles[0], handles[1], revs[1]);
+            multibody_joints.insert(handles[1], handles[2], revs[2]);
+            multibody_joints.insert(handles[2], handles[3], revs[3]);
+        } else {
+            impulse_joints.insert(curr_parent, handles[0], revs[0]);
+            impulse_joints.insert(handles[0], handles[1], revs[1]);
+            impulse_joints.insert(handles[1], handles[2], revs[2]);
+            impulse_joints.insert(handles[2], handles[3], revs[3]);
+        }
+
+        curr_parent = handles[3];
+    }
+}
+
+fn create_revolute_joints_with_limits(
+    bodies: &mut RigidBodySet,
+    colliders: &mut ColliderSet,
+    impulse_joints: &mut ImpulseJointSet,
+    multibody_joints: &mut MultibodyJointSet,
+    origin: Point<f32>,
+    use_articulations: bool,
+) {
+    let ground = bodies.insert(
+        RigidBodyBuilder::new_static()
+            .translation(origin.coords)
+            .build(),
+    );
+
+    let platform1 = bodies.insert(
+        RigidBodyBuilder::new_dynamic()
+            .translation(origin.coords)
+            .build(),
+    );
+    colliders.insert_with_parent(
+        ColliderBuilder::cuboid(4.0, 0.2, 2.0).build(),
+        platform1,
+        bodies,
+    );
+
+    let shift = vector![0.0, 0.0, 6.0];
+    let platform2 = bodies.insert(
+        RigidBodyBuilder::new_dynamic()
+            .translation(origin.coords + shift)
+            .build(),
+    );
+    colliders.insert_with_parent(
+        ColliderBuilder::cuboid(4.0, 0.2, 2.0).build(),
+        platform2,
+        bodies,
+    );
+
+    let z = Vector::z_axis();
+    let joint1 = RevoluteJoint::new(z).limit_axis([-0.2, 0.2]);
+
+    if use_articulations {
+        multibody_joints.insert(ground, platform1, joint1);
+    } else {
+        impulse_joints.insert(ground, platform1, joint1);
+    }
+
+    let joint2 = RevoluteJoint::new(z)
+        .local_anchor2(-Point::from(shift))
+        .limit_axis([-0.2, 0.2]);
+
+    if use_articulations {
+        multibody_joints.insert(platform1, platform2, joint2);
+    } else {
+        impulse_joints.insert(platform1, platform2, joint2);
+    }
+
+    // Let’s add a couple of cuboids that will fall on the platforms, triggering the joint limits.
+    let cuboid_body1 = bodies.insert(
+        RigidBodyBuilder::new_dynamic()
+            .translation(origin.coords + vector![-2.0, 4.0, 0.0])
+            .build(),
+    );
+    colliders.insert_with_parent(
+        ColliderBuilder::cuboid(0.6, 0.6, 0.6).friction(1.0).build(),
+        cuboid_body1,
+        bodies,
+    );
+
+    let cuboid_body2 = bodies.insert(
+        RigidBodyBuilder::new_dynamic()
+            .translation(origin.coords + shift + vector![2.0, 16.0, 0.0])
+            .build(),
+    );
+    colliders.insert_with_parent(
+        ColliderBuilder::cuboid(0.6, 0.6, 0.6).friction(1.0).build(),
+        cuboid_body2,
+        bodies,
+    );
+}
+
+fn create_fixed_joints(
+    bodies: &mut RigidBodySet,
+    colliders: &mut ColliderSet,
+    impulse_joints: &mut ImpulseJointSet,
+    multibody_joints: &mut MultibodyJointSet,
+    origin: Point<f32>,
+    num: usize,
+    use_articulations: bool,
+) {
+    let rad = 0.4;
+    let shift = 1.0;
+
+    let mut body_handles = Vec::new();
+
+    for i in 0..num {
+        for k in 0..num {
+            let fk = k as f32;
+            let fi = i as f32;
+
+            // NOTE: the num - 2 test is to avoid two consecutive
+            // fixed bodies. Because physx will crash if we add
+            // a joint between these.
+            let status = if i == 0 && (k % 4 == 0 && k != num - 2 || k == num - 1) {
+                RigidBodyType::Static
+            } else {
+                RigidBodyType::Dynamic
+            };
+
+            let rigid_body = RigidBodyBuilder::new(status)
+                .translation(vector![
+                    origin.x + fk * shift,
+                    origin.y,
+                    origin.z + fi * shift
+                ])
+                .build();
+            let child_handle = bodies.insert(rigid_body);
+            let collider = ColliderBuilder::ball(rad).build();
+            colliders.insert_with_parent(collider, child_handle, bodies);
+
+            // Vertical joint.
+            if i > 0 {
+                let parent_index = body_handles.len() - num;
+                let parent_handle = body_handles[parent_index];
+                let joint = FixedJoint::new().local_anchor2(point![0.0, 0.0, -shift]);
+
+                if use_articulations {
+                    multibody_joints.insert(parent_handle, child_handle, joint);
+                } else {
+                    impulse_joints.insert(parent_handle, child_handle, joint);
+                }
+            }
+
+            // Horizontal joint.
+            if k > 0 {
+                let parent_index = body_handles.len() - 1;
+                let parent_handle = body_handles[parent_index];
+                let joint = FixedJoint::new().local_anchor2(point![-shift, 0.0, 0.0]);
+                impulse_joints.insert(parent_handle, child_handle, joint);
+            }
+
+            body_handles.push(child_handle);
+        }
+    }
+}
+
+fn create_spherical_joints(
+    bodies: &mut RigidBodySet,
+    colliders: &mut ColliderSet,
+    impulse_joints: &mut ImpulseJointSet,
+    multibody_joints: &mut MultibodyJointSet,
+    num: usize,
+    use_articulations: bool,
+) {
+    let rad = 0.4;
+    let shift = 1.0;
+
+    let mut body_handles = Vec::new();
+
+    for k in 0..num {
+        for i in 0..num {
+            let fk = k as f32;
+            let fi = i as f32;
+
+            let status = if i == 0 && (k % 4 == 0 || k == num - 1) {
+                RigidBodyType::Static
+            } else {
+                RigidBodyType::Dynamic
+            };
+
+            let rigid_body = RigidBodyBuilder::new(status)
+                .translation(vector![fk * shift, 0.0, fi * shift * 2.0])
+                .build();
+            let child_handle = bodies.insert(rigid_body);
+            let collider = ColliderBuilder::capsule_z(rad * 1.25, rad).build();
+            colliders.insert_with_parent(collider, child_handle, bodies);
+
+            // Vertical joint.
+            if i > 0 {
+                let parent_handle = *body_handles.last().unwrap();
+                let joint = SphericalJoint::new().local_anchor2(point![0.0, 0.0, -shift * 2.0]);
+
+                if use_articulations {
+                    multibody_joints.insert(parent_handle, child_handle, joint);
+                } else {
+                    impulse_joints.insert(parent_handle, child_handle, joint);
+                }
+            }
+
+            // Horizontal joint.
+            if k > 0 {
+                let parent_index = body_handles.len() - num;
+                let parent_handle = body_handles[parent_index];
+                let joint = SphericalJoint::new().local_anchor2(point![-shift, 0.0, 0.0]);
+                impulse_joints.insert(parent_handle, child_handle, joint);
+            }
+
+            body_handles.push(child_handle);
+        }
+    }
+}
+
+fn create_spherical_joints_with_limits(
+    bodies: &mut RigidBodySet,
+    colliders: &mut ColliderSet,
+    impulse_joints: &mut ImpulseJointSet,
+    multibody_joints: &mut MultibodyJointSet,
+    origin: Point<f32>,
+    use_articulations: bool,
+) {
+    let shift = vector![0.0, 0.0, 3.0];
+
+    let ground = bodies.insert(
+        RigidBodyBuilder::new_static()
+            .translation(origin.coords)
+            .build(),
+    );
+
+    let ball1 = bodies.insert(
+        RigidBodyBuilder::new_dynamic()
+            .translation(origin.coords + shift)
+            .linvel(vector![20.0, 20.0, 0.0])
+            .build(),
+    );
+    colliders.insert_with_parent(
+        ColliderBuilder::cuboid(1.0, 1.0, 1.0).build(),
+        ball1,
+        bodies,
+    );
+
+    let ball2 = bodies.insert(
+        RigidBodyBuilder::new_dynamic()
+            .translation(origin.coords + shift * 2.0)
+            .build(),
+    );
+    colliders.insert_with_parent(
+        ColliderBuilder::cuboid(1.0, 1.0, 1.0).build(),
+        ball2,
+        bodies,
+    );
+
+    let joint1 = SphericalJoint::new()
+        .local_anchor2(Point::from(-shift))
+        .limit_axis(JointAxis::X, [-0.2, 0.2])
+        .limit_axis(JointAxis::Y, [-0.2, 0.2]);
+
+    let joint2 = SphericalJoint::new()
+        .local_anchor2(Point::from(-shift))
+        .limit_axis(JointAxis::X, [-0.3, 0.3])
+        .limit_axis(JointAxis::Y, [-0.3, 0.3]);
+
+    if use_articulations {
+        multibody_joints.insert(ground, ball1, joint1);
+        multibody_joints.insert(ball1, ball2, joint2);
+    } else {
+        impulse_joints.insert(ground, ball1, joint1);
+        impulse_joints.insert(ball1, ball2, joint2);
+    }
+}
+
+fn create_actuated_revolute_joints(
+    bodies: &mut RigidBodySet,
+    colliders: &mut ColliderSet,
+    impulse_joints: &mut ImpulseJointSet,
+    multibody_joints: &mut MultibodyJointSet,
+    origin: Point<f32>,
+    num: usize,
+    use_articulations: bool,
+) {
+    let rad = 0.4;
+    let shift = 2.0;
+
+    // We will reuse this base configuration for all the impulse_joints here.
+    let z = Vector::z_axis();
+    let joint_template = RevoluteJoint::new(z).local_anchor2(point![0.0, 0.0, -shift]);
+
+    let mut parent_handle = RigidBodyHandle::invalid();
+
+    for i in 0..num {
+        let fi = i as f32;
+
+        // NOTE: the num - 2 test is to avoid two consecutive
+        // fixed bodies. Because physx will crash if we add
+        // a joint between these.
+        let status = if i == 0 {
+            RigidBodyType::Static
+        } else {
+            RigidBodyType::Dynamic
+        };
+
+        let shifty = (i >= 1) as u32 as f32 * -2.0;
+
+        let rigid_body = RigidBodyBuilder::new(status)
+            .translation(vector![origin.x, origin.y + shifty, origin.z + fi * shift])
+            // .rotation(Vector3::new(0.0, fi * 1.1, 0.0))
+            .build();
+
+        let child_handle = bodies.insert(rigid_body);
+        let collider = ColliderBuilder::cuboid(rad * 2.0, rad * 6.0 / (fi + 1.0), rad).build();
+        colliders.insert_with_parent(collider, child_handle, bodies);
+
+        if i > 0 {
+            let mut joint = joint_template.clone();
+
+            if i % 3 == 1 {
+                joint = joint.motor_velocity(-20.0, 0.1);
+            } else if i == num - 1 {
+                let stiffness = 0.2;
+                let damping = 1.0;
+                joint = joint.motor_position(3.14 / 2.0, stiffness, damping);
+            }
+
+            if i == 1 {
+                joint = joint
+                    .local_anchor2(point![0.0, 2.0, -shift])
+                    .motor_velocity(-2.0, 0.1);
+            }
+
+            if use_articulations {
+                multibody_joints.insert(parent_handle, child_handle, joint);
+            } else {
+                impulse_joints.insert(parent_handle, child_handle, joint);
+            }
+        }
+
+        parent_handle = child_handle;
+    }
+}
+
+fn create_actuated_spherical_joints(
+    bodies: &mut RigidBodySet,
+    colliders: &mut ColliderSet,
+    impulse_joints: &mut ImpulseJointSet,
+    multibody_joints: &mut MultibodyJointSet,
+    origin: Point<f32>,
+    num: usize,
+    use_articulations: bool,
+) {
+    let rad = 0.4;
+    let shift = 2.0;
+
+    // We will reuse this base configuration for all the impulse_joints here.
+    let joint_template = SphericalJoint::new().local_anchor1(point![0.0, 0.0, shift]);
+
+    let mut parent_handle = RigidBodyHandle::invalid();
+
+    for i in 0..num {
+        let fi = i as f32;
+
+        // NOTE: the num - 2 test is to avoid two consecutive
+        // fixed bodies. Because physx will crash if we add
+        // a joint between these.
+        let status = if i == 0 {
+            RigidBodyType::Static
+        } else {
+            RigidBodyType::Dynamic
+        };
+
+        let rigid_body = RigidBodyBuilder::new(status)
+            .translation(vector![origin.x, origin.y, origin.z + fi * shift])
+            // .rotation(Vector3::new(0.0, fi * 1.1, 0.0))
+            .build();
+
+        let child_handle = bodies.insert(rigid_body);
+        let collider = ColliderBuilder::capsule_y(rad * 2.0 / (fi + 1.0), rad).build();
+        colliders.insert_with_parent(collider, child_handle, bodies);
+
+        if i > 0 {
+            let mut joint = joint_template.clone();
+
+            if i == 1 {
+                joint = joint
+                    .motor_velocity(JointAxis::AngX, 0.0, 0.1)
+                    .motor_velocity(JointAxis::AngY, 0.5, 0.1)
+                    .motor_velocity(JointAxis::AngZ, -2.0, 0.1);
+            } else if i == num - 1 {
+                let stiffness = 0.2;
+                let damping = 1.0;
+                joint = joint
+                    .motor_position(JointAxis::AngX, 0.0, stiffness, damping)
+                    .motor_position(JointAxis::AngY, 1.0, stiffness, damping)
+                    .motor_position(JointAxis::AngZ, 3.14 / 2.0, stiffness, damping);
+            }
+
+            if use_articulations {
+                multibody_joints.insert(parent_handle, child_handle, joint);
+            } else {
+                impulse_joints.insert(parent_handle, child_handle, joint);
+            }
+        }
+
+        parent_handle = child_handle;
+    }
+}
+
+fn do_init_world(testbed: &mut Testbed, use_articulations: bool) {
+    /*
+     * World
+     */
+    let mut bodies = RigidBodySet::new();
+    let mut colliders = ColliderSet::new();
+    let mut impulse_joints = ImpulseJointSet::new();
+    let mut multibody_joints = MultibodyJointSet::new();
+
+    create_prismatic_joints(
+        &mut bodies,
+        &mut colliders,
+        &mut impulse_joints,
+        &mut multibody_joints,
+        point![20.0, 5.0, 0.0],
+        4,
+        use_articulations,
+    );
+    create_actuated_prismatic_joints(
+        &mut bodies,
+        &mut colliders,
+        &mut impulse_joints,
+        &mut multibody_joints,
+        point![25.0, 5.0, 0.0],
+        4,
+        use_articulations,
+    );
+    create_revolute_joints(
+        &mut bodies,
+        &mut colliders,
+        &mut impulse_joints,
+        &mut multibody_joints,
+        point![20.0, 0.0, 0.0],
+        3,
+        use_articulations,
+    );
+    create_revolute_joints_with_limits(
+        &mut bodies,
+        &mut colliders,
+        &mut impulse_joints,
+        &mut multibody_joints,
+        point![34.0, 0.0, 0.0],
+        use_articulations,
+    );
+    create_fixed_joints(
+        &mut bodies,
+        &mut colliders,
+        &mut impulse_joints,
+        &mut multibody_joints,
+        point![0.0, 10.0, 0.0],
+        10,
+        use_articulations,
+    );
+    create_actuated_revolute_joints(
+        &mut bodies,
+        &mut colliders,
+        &mut impulse_joints,
+        &mut multibody_joints,
+        point![20.0, 10.0, 0.0],
+        6,
+        use_articulations,
+    );
+    create_actuated_spherical_joints(
+        &mut bodies,
+        &mut colliders,
+        &mut impulse_joints,
+        &mut multibody_joints,
+        point![13.0, 10.0, 0.0],
+        3,
+        use_articulations,
+    );
+    create_spherical_joints(
+        &mut bodies,
+        &mut colliders,
+        &mut impulse_joints,
+        &mut multibody_joints,
+        15,
+        use_articulations,
+    );
+    create_spherical_joints_with_limits(
+        &mut bodies,
+        &mut colliders,
+        &mut impulse_joints,
+        &mut multibody_joints,
+        point![-5.0, 0.0, 0.0],
+        use_articulations,
+    );
+
+    /*
+     * Set up the testbed.
+     */
+    testbed.set_world(bodies, colliders, impulse_joints, multibody_joints);
+    testbed.look_at(point![15.0, 5.0, 42.0], point![13.0, 1.0, 1.0]);
+}
+
+pub fn init_world_with_joints(testbed: &mut Testbed) {
+    do_init_world(testbed, false)
+}
+
+pub fn init_world_with_articulations(testbed: &mut Testbed) {
+    do_init_world(testbed, true)
+}
diff --git a/examples3d/ccd3.rs b/examples3d/ccd3.rs
index 8d676e3..2e00b86 100644
--- a/examples3d/ccd3.rs
+++ b/examples3d/ccd3.rs
@@ -44,7 +44,8 @@ pub fn init_world(testbed: &mut Testbed) {
      */
     let mut bodies = RigidBodySet::new();
     let mut colliders = ColliderSet::new();
-    let joints = JointSet::new();
+    let impulse_joints = ImpulseJointSet::new();
+