Help Grab Rope - VR

[tpaslou]

Update to latest version  (6.0.1), which also fixed multiple bugs in the initial 6.X release. In 6.0 you have to manually keep track of simplex counts, which is quite inconvenient.

After a bit of experimenting the code  for the grab resulted to be :

Code:

public void Grab()
    {
        var world = ObiColliderWorld.GetInstance();
        Debug.Log(pinConstraints);

        if (solver != null && collisionEvent != null)
        {
            Debug.Log("Collision");
            foreach (Oni.Contact contact in collisionEvent.contacts)
            {
                if (contact.distance < 0.01f)
                {
                    var contactCollider = world.colliderHandles[contact.bodyB].owner;
                    ObiSolver.ParticleInActor pa = solver.particleToActor[contact.bodyA];

                    Debug.Log(pa + " hit " + contactCollider);
                    if (canGrab)
                    {
                        if (contactCollider == obiCollider)
                        {
                            Debug.Log("Hand Collision");
                            var batch = new ObiPinConstraintsBatch();
                            //int solverIndex = rope.solverIndices[contact.bodyA];

                            int simplexStart = solver.simplexCounts.GetSimplexStartAndSize(contact.bodyA, out int simplexSize);
                            int particleIndex=0;
                            // starting at simplexStart, iterate over all particles in the simplex:
                            for (int i = 0; i < simplexSize; ++i)
                            {
                                particleIndex = solver.simplices[simplexStart + i];

                                // do something with each particle, for instance get its position:
                                var position = solver.positions[particleIndex];
                            }

                            Vector3 positionWS = solver.transform.TransformPoint(solver.positions[particleIndex]); // particle position from solver to world space
                            Vector3 positionCS = obiCollider.transform.InverseTransformPoint(positionWS); // particle position from world to collider space*/

                            batch.AddConstraint(rope.solverIndices[particleIndex], obiCollider, positionCS, Quaternion.identity, 0, 0, float.PositiveInfinity);
                            batch.activeConstraintCount = 1;
                            newBatch = batch;
                            pinConstraints.AddBatch(newBatch);

                            canGrab = false;

                            // this will cause the solver to rebuild pin constraints at the beginning of the next frame:
                            rope.SetConstraintsDirty(Oni.ConstraintType.Pin);

                        }
                    }
                }
            }
        }
    }

I grabbed a random index from the simplex. I used the enable-disable & follow constraint code for the Start & End particle attachment so I can pull the rope from whatever part I want and move it. There will be some future improvements.