The rod should have self collision, but we don't want adjacent element to collide with each other. Therefor a collision pair exclusion feature was added.
When using direct solver when in which both edge elements are static/kinematic the constraints are not being applied. Therefor, only one edge is static and the other edge is connected to a kinematic object using a joint.
Since I wasn't able to to find a lock joint, I used TargetAngleMotorHingeJoint.
The demo supports two options for rod constraints handling, with the default option of direct solver.
The collision handling was very sensitive and increasing the contact stiffness made a huge difference in fidelity. It would be great if the original parameters could be shared (e.g. timeStepSize, dimension of each element, mass density, number of sub steps etc).
A zero mass rigid body is assumed to be static and the render mesh is never updated, so in our demo the render mesh of the kinematic object is explicitly updated.
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What
Following this discussion, this demo is trying to reproduce the results in this video and this paper
Details and limitations
results
KnotFormation-2025-03-19.16-06-32.mp4