Rope joint limits not applied (code + images)

[ThomasCartier]

Hi,
Using a simple cube and a sphere, using ropejoints, I expected the cube to deform and hang. Instead, it only deforms, ignoring the limits of the ropejoint.
I put this question in this section (discussion) because it is certainly me not doing something properly and not the engine.

The example take some simplified shapes.

Init cube (RB) shape with a subdiv:

Init cube (RB) showing the sphere (collider) inside of it:

Larger view:

Deformation

Expected result:

So the deformation part works just fine.
The issue is that the cube should not keep going down when some limits are applied:

let mut impulse_joint_set = ImpulseJointSet::new();

let mut lambda_configure = |j: &Vec<&RigidBodyHandle>| -> Result<(), u32> {

        // ------------------------------
        // We have our first triangle
        // Apply the distance constraint
        // ------------------------------

        let hd0 = match rigid_body_set.get(*j[0]) {
                Some(e) => e.translation(),
                None => return Err(500)
        };

        let hd1 = match rigid_body_set.get(*j[1]) {
                Some(e) => e.translation(),
                None => return Err(501)
        };

        let hd2 = match rigid_body_set.get(*j[2]) {
                Some(e) => e.translation(),
                None => return Err(502)
        };


        // -------------
        // Distances
        // -------------
        let dist_0_1 = nalgebra::distance(&hd0.xyz().into(), &hd1.xyz().into());

        let dist_0_2 = nalgebra::distance(&hd0.xyz().into(), &hd2.xyz().into());

        let dist_1_2 = nalgebra::distance(&hd1.xyz().into(), &hd2.xyz().into());

        // ----------------
        // Now the joints
        // ----------------
        let local_center = Point3::<f32>::origin();

        macro_rules! rope_set {
                ($proper_handler0 : expr, $proper_handler1 : expr, $dist_min : expr, $dist_max : expr) => {{

                        let mut rope_joint = RopeJointBuilder::new()
                                .local_anchor1(local_center)
                                .local_anchor2(local_center)
                                .build();

                        rope_joint
                                .data
                                .set_limits(rapier3d::dynamics::JointAxis::Y, [$dist_min, $dist_max]);

                        impulse_joint_set.insert(*$proper_handler0, *$proper_handler1, rope_joint, true);
                }

                {

                        let mut rope_joint = RopeJointBuilder::new()
                                .local_anchor1(local_center)
                                .local_anchor2(local_center)
                                .build();

                        rope_joint
                                .data
                                .set_limits(rapier3d::dynamics::JointAxis::X, [$dist_min, $dist_max]);

                        impulse_joint_set.insert(*$proper_handler0, *$proper_handler1, rope_joint, true);
                }

                {

                        let mut rope_joint = RopeJointBuilder::new()
                                .local_anchor1(local_center)
                                .local_anchor2(local_center)
                                .build();

                        rope_joint
                                .data
                                .set_limits(rapier3d::dynamics::JointAxis::Z, [$dist_min, $dist_max]);

                        impulse_joint_set.insert(*$proper_handler0, *$proper_handler1, rope_joint, true);
                }};
        }

        // ---------
        // Limits
        // ---------
        rope_set!(j[0], j[1], 0., dist_0_1);

        rope_set!(j[0], j[2], 0., dist_0_2);

        rope_set!(j[1], j[2], 0., dist_1_2);


        return Ok(());
};

I over-constrain the cube, with each triangle edge having a joint, irrespective of an already registered edge with a former triangle.
In this example, the cube should keep its cube look, almost no deformation, because the max limit is the current distance between the points. And we should never reach the min in that simulation.

Is there an obvious issue with the setup ?

Thanks

[ThomasCartier]

Even setting the dist_X_X to 0.1, the simulation doesn't respect the distance between the rigid bodies, causing the cube to deform more than necessary.

[ThomasCartier]

It looks like the joints are messing the result up. Not best approach anyway, it is in the realm of deformable bodies.