Obi Rope and VR

[josemendez]

Thanks for your answers.


1. According to rope behavior, what I meant was: is there a possibility of anything weird happening like e. g. while I was making a rope out of RigidBody capsules connected with joints. (During teleportation or quick moves, the whole line wobbled wildly through whole scene.)
2. Ok, which total length of the lines won’t cause problems for Intel’s 4-core or 6-core processor? Or number of cores doesn`t have impact on Obi Rope? 
4. Unity is my first game engine. I need your asset for creating simple ordinary cables, familiarity with all those terms is really required? ? ????

1. Obi is unconditionally stable, which means the simulation will never blow up, jitter, or become "crazy". However unexpected things can happen if you don't fully understand what you're doing. Teleporting physical simulations around a scene requires you to reason about the order in which things happen in the engine to avoid adding energy to the simulation. The correct order should be: #1 simulation stops #2 teleport #3 simulation restarts. Since Unity performs physics during FixedUpdate(), this usually requires you to stop the simulation, teleport the object, make a coroutine that uses WaitForFixedUpdate(), then resume the simulation.

2. In addition to rope length, it depends on rope resolution (how many particles per length unit), what level of rigidness you need, whether you need self-collisions or not, how accurate you need rendering to be, and lots other things. As a rough estimate, 3000 particles can be run comfortably on most 4-core processors, including meshing and rendering. At average resolution, and assuming they are part of multiple ropes, you'd be able to simulate around 200 short ropes before encountering performance issues.

3. It is essential. Not just for working with Obi but with pretty much all physics engines, specially when trying to make non-trivial things (constraint chains, of which ropes/cables are an example, are one of them). In addition to that, many engines limit your options or hand-hold you a lot to make things easier, but Obi does the opposite: it leaves all options open for you to explore and achieve exactly what you want, no artificially imposed limits. Knowing how to get there requires some knowledge, though.

Also, the definition of "simple, ordinary cables" varies a lot from person to person. I've seen similar terms used to refer to the cable setup for a piece of industrial machinery, which ended up requiring engineering-grade simulators. Cables are only simple to simulate if they don't have to support the weight of other objects, if they don't self-collide or collide with other cables, and if they're relatively short (less than 3-4 meters). Obi can do all these things, but increasing levels of understanding are needed to achieve them.