sequence of short ropes connecting pinned objects – problem with stretchiness/jitter

[josemendez]

Hi –

I'm building a vertical chain of ropes and pinned objects (object/rope/object/rope/object, etc) and the longer the sequence gets, the more elastic the rope gets (if the rigidbodies have a mass of 1) or the more uncontrollably jittery it is (if the rigidbodies have masses of less than 1). 

I've gone through the documentation and forums looking for answers – the only suggestion I can find is to make sure that the masses of the rope particles are in a reasonable ratio to the rigidbody mass. But when I change the rigidbody masses to something small like 0.2, everything starts jittering – the more objects in the chain, the more jitter.

The only solution I've been able to find is to leave the rigidbody masses at 1, and set the Distance Constraints Stretching Scale of the ropes to something like 0.25. This works, although it makes everything jump around when the scene starts.

Is there something I'm missing? Suggestions?

Hi there,

The first thing you should try is to increase the amount of distance and pin constraint iterations (found in the ObiSolver component). Longer chains of constraints greatly reduce the convergence for iterative solvers (which is of course solved by iterating more times).

A small introduction to iterative solvers we wrote on our blog:
http://blog.virtualmethodstudio.com/2017...3-solvers/

Also reducing the timestep can help a lot. (ProjectSettings->Time->Fixed timestep)