Stiff wire simulation

[jfeng94]

I'm interested in using ObiWire to simulate stiff wires (like copper wires) that the user can bend at will but maintains its basic shape when subject to gravity.
Does anyone have any tips on how to set up the solver/constraints to get this sort of behavior? Thanks in advance!

[josemendez]

I'm interested in using ObiWire to simulate stiff wires (like copper wires) that the user can bend at will but maintains its basic shape when subject to gravity.
Does anyone have any tips on how to set up the solver/constraints to get this sort of behavior? Thanks in advance!

Hi there,

Obi Rope cannot currently simulate these. They are typically referred to as "rods" in simulation jargon, and are very different from ropes/cables: in addition to having stretch/bend elastic potentials, they also require the computation of twist/shear. This is usually accomplished by constraining the Darboux vector, which requires particles in the rope to hold orientation information (quaternions) instead of being just positions in space.

In layman's terms: Rods are aware of twisting motion and have certain plastic behavior, so they can "remember" their original shape, but somewhat keep a new one if you force them to (think old telephone cables, the curly ones). Ropes are not.

We are working on integrating the following paper, so this is likely to be supported in the future:
https://diglib.eg.org/handle/10.2312/sca20161234

[jfeng94]

Hi Jose,

Thanks so much for the quick reply! Sad to hear that it's not supported yet.

[MariuszVR]

Hi there,

Obi Rope cannot currently simulate these. They are typically referred to as "rods" in simulation jargon, and are very different from ropes/cables: in addition to having stretch/bend elastic potentials, they also require the computation of twist/shear. This is usually accomplished by constraining the Darboux vector, which requires particles in the rope to hold orientation information (quaternions) instead of being just positions in space.

In layman's terms: Rods are aware of twisting motion and have certain plastic behavior, so they can "remember" their original shape, but somewhat keep a new one if you force them to (think old telephone cables, the curly ones). Ropes are not.

We are working on integrating the following paper, so this is likely to be supported in the future:
https://diglib.eg.org/handle/10.2312/sca20161234

Hi, Is this supported now? 
I need just something that can behave as a simple wire.... from 1 inch to like 10 inches longs.... that I can bend in VR ... would be used to connect some pieces together, like electrical boards. hmm

[josemendez]

Hi, Is this supported now? 
I need just something that can behave as a simple wire.... from 1 inch to like 10 inches longs.... that I can bend in VR ... would be used to connect some pieces together, like electrical boards. hmm

Working on it, a few more weeks till they're ready. They will ship in Obi Rope 4.0, compatible with Unity 2018.1 and up. Here's a sneak peek showing spring simulation and plectoneme formation:


Just make sure you really need full rods instead of simple ropes for your purpose, as they're a bit more expensive than ropes (around 10-15% more). Also they consume slightly more memory as they need to store per-segment quaternions and inertia tensors.

[MariuszVR]

Working on it, a few more weeks till they're ready. They will ship in Obi Rope 4.0, compatible with Unity 2018.1 and up. Here's a sneak peek showing spring simulation and plectoneme formation:


Just make sure you really need full rods instead of simple ropes for your purpose, as they're a bit more expensive than ropes (around 10-15% more). Also they consume slightly more memory as they need to store per-segment quaternions and inertia tensors.

ohhh maaan... this looks great! In my case I will want to use the system so a player can attach both ends of the wire to some electronics boards etc for kind of training purposes. Will see. Thanks for response!

[Erman]

Hello 

Is it possible tool to use obiRope 4.0 (rod sneak peek) as a guidewire? Guidewire through a tool try to aim a tube's hole(entrance)  then put guidewire into that tube.

[josemendez]

Hello 

Is it possible tool to use obiRope 4.0 (rod sneak peek) as a guidewire? Guidewire through a tool try to aim a tube's hole(entrance)  then put guidewire into that tube.

Hi there,

Nope. Ropes and rods are modeled as a string of spherical solid particles.

For a guidewire you'd need collision detection against hollow cylindrical sections instead, which is a really specialized use case. I highly doubt you can find a pre-made solution for this.