Disaster Syndrome - Rope physics

Gabriel Brasil and Michael Fuller's amazing VR adventures! Today, we tried OBI Rope physics plugin in Unity together with VR controllers and it was a success! VR High fives for everybody!


November 10, 2018

Class: Desert of the Real - Deep dive in Social VR

Instructor: Igal Nassima


Created a new Unity Project named “Disaster Syndrome”.

Setup SteamVr and its basic interactions for our first scene.

GOALS 1: create two networked characters and create the rope dynamics interactions

OBI Rope Asset

We bought the OBI Rope Particle at the Unity Asset Store, as recommended by our instructor Igal.

OBI Rope comes with several solutions for our Rope dynamics.

Goal 1.1: Use OBI Rope plugin in conjunction with steam vr.

Obi is a collection of particle-based physics plugins for Unity. That means that everything is made out of small spheres called particles. Particles can affect each other, affect and be affected by other objects all through the use of constraints.”

“Obi only takes care of particle allocation and constraint setup. The physical simulation itself is performed by Oni (japanese for "demon") which is a completely engine-agnostic particle physics library written in C++. You can think of Obi as the middle-layer between Unity and Oni. Let's take a look at Obi's component architecture, and why it's made that way…”

Looked at OBI webpage for manuals and tutorials on setting up the plugin


Goal 1.1 achieved!: It works!

We started with the Obi Rope sample scenes, looking at each of different mechanics available. The Rope Chain scene has a chain attached to one Cube object that can be controlled by the user in the Scene window, and at the other end of the chain there is a big ball. When the Cube is moved, the chain and the ball move accordingly, knocking down physics objects in the scene.

After playing with the scene, we copied it and added the Steam VR plugins to it: Teleporting; Player; Teleport Area; Interactables and Throwable.

The goal was to attach the chain link to a throwable object,

First we just made the original chain Cube a child of the hand, but it couldn’t be thrown and the pivot point was far away from the hand/controller position.

Our second test involved adding Steam Vr’s “Throwable” and “Interactable” to the Cube attached to the chain. This made the cube move erratically on the scene, apparently “running” away from my hand. It was funny, but not what we are looking for.

Third was the charm, when we created a new throwable object “Capsule” and just added the “Obi Particle Rendered” and assigned the “Obi Chain” object/actor to it.

The Sphere was positioned on a platform since I couldn’t physically reach it on the floor (wonders of VR). In a moment the reminded us of Raiders of the Lost Arc, I carefully approached the “Capsule” and it remained attached to the chain and the ball. When thrown, it worked: The Capsule dragged the chain and the sphere with it.