Help Adding pin constraints to a rope at runtime

[Chilly5]

Hello,

I am working on a game in Unity where I want to add pin constraints all the way down the Obi Rope at runtime. Every unit of the rope should be covered with a constraint. The idea is that I'm attaching selectable colliders that can be "grabbed" by the player and then swung on.

I copied almost exactly the code from the "adding/removing constraints" page on the website here: http://obi.virtualmethodstudio.com/tutor...aints.html
Unity didn't like a few of the casts so I modified it slightly, but it's more or less the same.

Here's my current script:

Code:

    [SerializeField]
    private GameObject _networkedGrabPoint;

    private ObiRope _obiRope;

    [SerializeField]
    private List<GameObject> _chainLinks = new List<GameObject>();

    [SerializeField]
    private List<GameObject> _ropeLinks = new List<GameObject>();

    void Start()
    {
        _obiRope = GetComponentInChildren<ObiRope>();
        _chainLinks = _obiRope.chainLinks;

        for (int i = 0; i < _obiRope.positions.Length; i++)
        {
            GameObject _ropeLink = GameObject.Instantiate(_networkedGrabPoint, transform);
            _ropeLink.transform.localPosition = _obiRope.positions[i];
            _ropeLinks.Add(_ropeLink);
        }
    }
    
    void Update () {
        if (Input.GetKeyDown(KeyCode.R))
        {
            ObiPinConstraints constraints = _obiRope.GetComponent<ObiPinConstraints>();
            ObiPinConstraintBatch batch = constraints.GetBatches() as ObiPinConstraintBatch;
            
            // remove the constraints from the solver, because we cannot modify the constraints list while the solver is using it.
            constraints.RemoveFromSolver(null);

            ObiCollider ropeLink = _ropeLinks[0].GetComponent<ObiCollider>();
            batch.AddConstraint(0, ropeLink as ObiColliderBase, Vector3.zero, 1.0f);

            // add all constraints back:
            constraints.AddToSolver(null);
            
        }
    }

Almost word for word copied from what was given on the website. For some reason it didn't like the line "(ObiPinConstraintBatch)constraints.Getbatches()[0]" so I modified it to "constraints.GetBatches() as ObiPinConstraintBatch".

Right now, it's giving me a "null reference exception: object reference not set to an instance of an object" error on this line: batch.AddConstraint(0, ropeLink as ObiColliderBase, Vector3.zero, 1.0f);

I don't understand why. I checked the ObiColliderBase and it seems to definitely exist so I don't know why it would give me a null reference error there.

Any help would be very appreciated!

Thank you.