For creating runtime tight knot

[josemendez]

Hi there!
What's the current state of supporting this fancy thing called "sliding" constraints? It's exactly what I need, but I have no clue of how to integrate it myself in Obi.

Hi!

Sliding constraints are a quite specific use case, almost only useful for suturing. I don't think they will be added to Obi anytime soon.

Adding new constraints to the Burst backend can be done, but requires in-depth knowledge of Obi's architecture as well as position-based dynamics. You could also add it in the form of a velocity-based constraint outside the main constraint loop, which would be easier to do but not as effective: basically you have a point "P" in space trough which the rope must pass, get the rope segment "S" closer to it, calculate the velocity of "S" relative to "P" and project it to the plane orthogonal to the edge, then negate the result and distribute it between the two particles at the ends of the segment. It's a rough idea but would work.