[Cocos Creator 3.8.5]Jittering When Two RigidBodies Snap Collectively – Cocos Creator

I’m engaged on a Cocos 3D undertaking and have run right into a physics problem with two inflexible our bodies:

Once I click on the higher physique, it drops freely into the decrease groove—however as quickly because it contacts the groove, it jitters and finally falls out of the display screen. What I truly need is:

• As soon as it settles within the groove, and no exterior forces are performing on it, it ought to stay completely nonetheless.
• If an exterior power is later utilized, it ought to reply usually to that power.

Right here’s a brief demo of the issue:

Each nodes use the identical BoxItem script. Related snippets observe:

// Referred to as each body
protected replace(dt: quantity): void {
  const rigidBodies = this.node.getComponentsInChildren(RigidBody);
  for (const physique of rigidBodies) {
    // Stop any undesirable spin when mounted
    if (this.isFixed) {
      physique.setAngularVelocity(v3(0, 0, 0));
    }
  }
}

// Initialization (e.g. onLoad)
const rigidBodies = this.node.getComponentsInChildren(RigidBody);
for (const physique of rigidBodies) {
  physique.sort         = RigidBody.Kind.DYNAMIC;
  physique.useGravity   = true;
  physique.angularFactor = v3(0, 0, 1);      // Solely permit rotation round Z
  if (this._boxModel?.mass) {
    physique.mass = this._boxModel.mass;
  }
}

What I’ve Tried So Far

• Clamping angular velocity to zero when isFixed
• Guaranteeing each our bodies use the identical mass and gravity settings

Desired Conduct

• After the higher physique falls into the groove, it ought to come to relaxation and keep precisely in place if no different forces act on it.
• If one other power (e.g. a collision or person interplay) is later utilized, it ought to react usually.

Questions

1. What’s inflicting that steady jitter when it first contacts the groove?
2. Which physics properties (e.g., linear/angular damping, friction, contact/collision margins) ought to I alter to let it stabilize and lock in place?

Thanks upfront for any insights or suggestions!