Help Rope reacting weird

[SilverStanley]

Hello,
Sorry to keep spamming help related topics here. Just found another issue that cant figure out what the problem is.
The rope that I have can interact with the quest controller. I am using the ObiContactGrabber which 'JoseMendez' shared quite a while back in the forums under the 'Grab in VR' thread.
After the initial contact with the particles, the particles begin to react weirdly pinching at 2 points alone and squeezing the rope after which point it just launches violently somewhere.

The physics material for the rope is High Friction for both the floor and the shelf. There are 5 control points for the rope's path, 4 of them have the same phases but separated by one in the middle, like so 10-10-0-10-10, the place where the pinching occurs is not near the control points at all. The floor and shelf are in phase 25 so that they will not cause any issues in particles falling into the collider.

The solver is running at 3 substeps with Substeps to Unity physics checked true.

Rope Reaction 

Regards,
Stanley

[josemendez]

Hi Stanley,

What phase values are you using for the controller's colliders? Also, how are you using the contact grabber? By the end of the video it seems like a couple particles in the rope have much higher mass than the rest, but it's hard to tell.

[SilverStanley]

Hi Stanley,

What phase values are you using for the controller's colliders? Also, how are you using the contact grabber? By the end of the video it seems like a couple particles in the rope have much higher mass than the rest, but it's hard to tell.

1. Phase Value for the controllers are 25
2. ContactGrabber class is basically a copy-paste of your code with some modifications, to help grab and release the particles when using the quest controllers.
3. The Mass for all control points are 0.5

Regards,
Stanley

[josemendez]

1. Phase Value for the controllers are 25
2. ContactGrabber class is basically a copy-paste of your code with some modifications, to help grab and release the particles when using the quest controllers.
3. The Mass for all control points are 0.5

Regards,
Stanley

Hi Stanley,

I'm unable to reproduce this behavior using the same parameters you've posted. Would it be possible for you to share the modifications made to ContactGrabber?

[SilverStanley]

Code:

using UnityEngine;
using System.Collections.Generic;
using Obi;

//Sample component that makes a collider "grab" any particle it touches (regardless of which Actor it belongs to).
[RequireComponent(typeof(ObiCollider))]
public class ObiContactGrabber : MonoBehaviour
{

    public ObiSolver solver;

    //Helper class that stores the index of a particle in the solver, its position in the grabber's local space, and its inverse mass previous to being grabbed.
    //This makes it easy to tell if a particle has been grabbed, update its position while grabbing, and restore its mass after being released.
    private class GrabbedParticle : IEqualityComparer<GrabbedParticle>
    {
        public int index;
        public float invMass;
        public Vector3 localPosition;

        public GrabbedParticle(int index, float invMass)
        {
            this.index = index;
            this.invMass = invMass;
        }

        public bool Equals(GrabbedParticle x, GrabbedParticle y)
        {
            return x.index == y.index;
        }

        public int GetHashCode(GrabbedParticle obj)
        {
            return index;
        }
    }

    private ObiSolver.ObiCollisionEventArgs collisionEvent;                                     //Store the current collision event
    private ObiCollider localCollider;                                                          //the collider on this gameObject.
    private HashSet<GrabbedParticle> grabbedParticles = new HashSet<GrabbedParticle>();         //Set to store all currently grabbed particles.
    private HashSet<ObiActor> grabbedActors = new HashSet<ObiActor>();                          //Set of softbodies grabbed during this step.

    private Matrix4x4 grabber2Solver;
    private Matrix4x4 solver2Grabber;

    private void Awake()
    {
        localCollider = GetComponent<ObiCollider>();
    }

    private void OnEnable()
    {
        if (solver != null)
            solver.OnCollision += Solver_OnCollision;
    }

    private void OnDisable()
    {
        if (solver != null)
            solver.OnCollision -= Solver_OnCollision;
    }

    private void Solver_OnCollision(object sender, Obi.ObiSolver.ObiCollisionEventArgs e)
    {
        // Calculate transform matrix from grabber to world space (Note: if using local space simulation, postmultiply with solver.transform.localToWorldMatrix)
        solver2Grabber = transform.worldToLocalMatrix * solver.transform.localToWorldMatrix;
        // and its inverse:
        grabber2Solver = solver2Grabber.inverse;
        collisionEvent = e;
    }

    private void UpdateParticleProperties()
    {
        // Update rest shape matching of all grabbed softbodies:
        foreach (ObiActor actor in grabbedActors)
        {
            actor.UpdateParticleProperties();
        }
    }

    //Creates and stores a GrabbedParticle from the particle at the given index.
    //Returns true if we sucessfully grabbed a particle, false if the particle was already grabbed.
    private bool GrabParticle(int index)
    {
        GrabbedParticle p = new GrabbedParticle(index, solver.invMasses[index]);
        // in case this particle has not been grabbed yet:
        if (!grabbedParticles.Contains(p))
        {
            // record the particle's position relative to the grabber, and store it.
            p.localPosition = solver2Grabber.MultiplyPoint3x4(solver.positions[index]);
            grabbedParticles.Add(p);

            // Set inv mass and velocity to zero:
            solver.invMasses[index] = 0;
            solver.velocities[index] = Vector4.zero;

            return true;
        }
        return false;
    }

    // Grabs all particles currently touching the grabber.
    public bool Grab()
    {
        grabbedActors.Clear();
        var world = ObiColliderWorld.GetInstance();

        if (solver != null && collisionEvent != null)
        {
            foreach (Oni.Contact contact in collisionEvent.contacts)
            {
                // this one is an actual collision:
                if (contact.distance < 0.01f)
                {
                    var contactCollider = world.colliderHandles[contact.other].owner;
                    // if the current contact references our collider, proceed to grab the particle.
                    if (contactCollider == localCollider)
                    {
                        // try to grab the particle, if not already grabbed.
                        if (GrabParticle(contact.particle))
                        {
                            grabbedActors.Add(solver.particleToActor[contact.particle].actor);
                            return true;
                        }
                    }
                }
            }
        }

        UpdateParticleProperties();
        return false;
    }

    // Releases all currently grabbed particles. This boils down to simply resetting their invMass.
    public void Release()
    {
        // Restore the inverse mass of all grabbed particles, so dynamics affect them.
        foreach (GrabbedParticle p in grabbedParticles)
            solver.invMasses[p.index] = p.invMass;

        UpdateParticleProperties();
        grabbedActors.Clear();
        grabbedParticles.Clear();
    }

    // Updates the position of the grabbed particles.
    private void FixedUpdate()
    {
        foreach (GrabbedParticle p in grabbedParticles)
            solver.positions[p.index] = grabber2Solver.MultiplyPoint3x4(p.localPosition);
    }

    public bool RightControl = false;

    private void Update()
    {
        if (!RightControl)
        {
            if (Input.GetKeyDown(KeyCode.Joystick1Button14))
                Grab();
            if (Input.GetKeyUp(KeyCode.Joystick1Button14))
                Release();
        }
        else
        {
            if (Input.GetKeyDown(KeyCode.Joystick2Button15))
                Grab();
            if (Input.GetKeyUp(KeyCode.Joystick2Button15))
                Release();
        }
    }
}

This is what I have.

Regards,
Stanley

[josemendez]

Still unable to reproduce any weird behavior using this code  .What does the collider setup for your controllers look like? Would it be possible to take a look at the actual project?

[SilverStanley]

Still unable to reproduce any weird behavior using this code  .What does the collider setup for your controllers look like? Would it be possible to take a look at the actual project?

sorry for the late reply,
I will zip up a package over the weekend. Where should I send it to?

Regards
Stanley

[josemendez]

sorry for the late reply,
I will zip up a package over the weekend. Where should I send it to?

Regards
Stanley

Hi Stanley,

Send it to support(at)virtualmethodstudio.com. It's me reading that inbox .

[SilverStanley]

Hi Stanley,

Send it to support(at)virtualmethodstudio.com. It's me reading that inbox .

I sent to project to the email mentioned above. It is under the subject Rope reacting weird - Project File.

[SilverStanley]

Hello Jose,
Was there anything I did wrong in the rope setup?

Regards,
Stanley