Help Saving Rope State

[josemendez]

https://imgur.com/a/4N29ICl

The rope in the screenshot is attached to the yellow object at its upper most particle with a dynamic particle attachment and that particle is placed in the yellow object, their colliders (both particle and the yellow object) has the same phase so that they dont collide. But when the rope moves, it's end separates from the object just like in the screenshot. Also the yellow object in the screenshot has rigidbody and obi rigidbody and the other and of the rope is attached to an object with a static particle attachment. Is the any way to avoid this?

Hi,

I assume you're using a FixedUpdater and not a LateUpdater, right?

A slight separation will always exist regardless of what kind of updater you use, but in LateUpdater it would be more pronounced due to variable time stepping.

Constraints (such as the pin constraints created by a dynamic attachment) are "reactive": only when there's a slight separation between the current particle position and the position it is supposed to be, does the constraint apply a force to the particle. If you're pulling the rope from the other end with a static attachment (which simply sets the particle position every step), the constraint will apply a force to both the rope and the rigidbody to held them together at the attachment point, but won't instantaneously snap them together. This is just how iterative physics solvers work (pretty much all realtime engines).

You could increase the amount of pin constraint iterations, and/or use more substeps. This will reduce the separation, but will never completely eliminate it.

Anyway, this should be a very slight separation, not the huge gap in your screenshot. I can't tell for sure if that's the cause, or something entirely different.