18-03-2022, 05:57 PM
(This post was last modified: 18-03-2022, 06:01 PM by josemendez.)
(18-03-2022, 04:26 PM)Portz Wrote: Hi!
I'm currently developing a suturing simulator for medicine students, and I'm having big trouble finding a way to replicate this exercise in my app (https://www.youtube.com/watch?v=DIUy3jeM6sY). As you can see from this second video (https://www.youtube.com/watch?v=5ZXG9LiYFdc), even with self and surface-based collisions activated and using only distance fields for collisions, the rope passes through itself and objects, making creating a knot impossible. Do you have any suggestions to solve or "bypass" (IDK, maybe dynamically substituting the rope blueprint with a "baked knot" by hitting a controller button at the right time?) this problem?
In the attachment, you can find screenshots of the solver and rope parameters.
Thank you for your attention!
Hi!
Can’t be sure what the problem is without really delving into specifics of your user input implementation (are these manipulators force-driven rigidbodies or simply kinematic transforms?) but one thing stands a lot in your settings: you’re using 20 collision iterations (that is, collider-particle collisions have very high priority) but only 1 particle collision iteration (very low priority for particle-particle collisions).
At the very least you should use the same amount of particle collision iterations that you do for all other constraints, since these are what determine how robust rope-rope collision detection is.
Particle friction constraints are also quite important when making knots, as these determine the quality of forces tangential to contact points.
On a side note, 20 iterations and 10 substeps is absolute overkill, it yields 200 iterations per step (not even per frame). Try 2 iterations for all constraints and 10 substeps.
Let me know whether this improves the results.