Merge pull request #571 from AnonymousAcid7787/fix-Setting-the-motor-…

…position-of-a-Spherical-multibody-joint-is-broken

Fix #416 Update spherical joint motor position

examples3d/all_examples3.rs

@@ -38,6 +38,7 @@ mod debug_chain_high_mass_ratio3;
 mod debug_cube_high_mass_ratio3;
 mod debug_internal_edges3;
 mod debug_long_chain3;
+mod debug_multibody_ang_motor_pos3;
 mod joint_motor_position3;
 mod keva3;
 mod locked_rotations3;
@@ -149,6 +150,10 @@ pub fn main() {
             debug_shape_modification3::init_world,
         ),
         ("(Debug) deserialize", debug_deserialize3::init_world),
+        (
+            "(Debug) multibody ang. motor pos.",
+            debug_multibody_ang_motor_pos3::init_world,
+        ),
     ];
 
     // Lexicographic sort, with stress tests moved at the end of the list.

examples3d/debug_multibody_ang_motor_pos3.rs

@@ -0,0 +1,31 @@
+use rapier3d::prelude::*;
+use rapier_testbed3d::Testbed;
+
+pub fn init_world(testbed: &mut Testbed) {
+    let mut bodies = RigidBodySet::new();
+    let mut colliders = ColliderSet::new();
+    let impulse_joints = ImpulseJointSet::new();
+    let mut multibody_joints = MultibodyJointSet::new();
+
+    let ground = RigidBodyBuilder::fixed().translation(vector![0.0, 0.0, 0.0]);
+    let body = bodies.insert(ground);
+    let collider = ColliderBuilder::cuboid(1.0, 1.0, 1.0);
+    colliders.insert_with_parent(collider, body, &mut bodies);
+
+    let rigid_body = RigidBodyBuilder::dynamic().position(Isometry::translation(0.0, 1.0, 0.0));
+    let body_part = bodies.insert(rigid_body);
+    let collider = ColliderBuilder::cuboid(1.0, 1.0, 1.0).density(1.0);
+    colliders.insert_with_parent(collider, body_part, &mut bodies);
+
+    let joint = SphericalJointBuilder::new()
+        .local_anchor1(point![0.0, 4.0, 0.0])
+        .local_anchor2(point![0.0, 0.0, 0.0])
+        .motor_position(JointAxis::AngX, 1.0, 1000.0, 200.0)
+        .motor_position(JointAxis::AngY, 0.0, 1000.0, 200.0)
+        .motor_position(JointAxis::AngZ, 0.0, 1000.0, 200.0);
+
+    multibody_joints.insert(body, body_part, joint, true);
+
+    testbed.set_world(bodies, colliders, impulse_joints, multibody_joints);
+    testbed.look_at(point![20.0, 0.0, 0.0], point![0.0, 0.0, 0.0]);
+}

src/dynamics/joint/multibody_joint/multibody_joint.rs

@@ -115,6 +115,9 @@ impl MultibodyJoint {
                 let angvel = Vector3::from_row_slice(&vels[curr_free_dof..curr_free_dof + 3]);
                 let disp = UnitQuaternion::new_eps(angvel * dt, 0.0);
                 self.joint_rot = disp * self.joint_rot;
+                self.coords[3] += angvel[0] * dt;
+                self.coords[4] += angvel[1] * dt;
+                self.coords[5] += angvel[2] * dt;
             }
             _ => unreachable!(),
         }