Rope Physics

DistanceJoint3D.cs

using UnityEngine;

public class DistanceJoint3D : MonoBehaviour {

    public Transform ConnectedRigidbody;
    public bool DetermineDistanceOnStart = true;
    public float Distance;
    public float Spring = 0.1f;
    public float Damper = 5f;

    protected Rigidbody Rigidbody;

    void Awake()
    {
        Rigidbody = GetComponent<Rigidbody>();
    }

    void Start()
    {
        if (DetermineDistanceOnStart && ConnectedRigidbody != null)
            Distance = Vector3.Distance(Rigidbody.position, ConnectedRigidbody.position);
    }

    void FixedUpdate()
    {

        var connection = Rigidbody.position - ConnectedRigidbody.position;
        var distanceDiscrepancy = Distance - connection.magnitude;

        Rigidbody.position += distanceDiscrepancy * connection.normalized;

        var velocityTarget = connection + (Rigidbody.velocity + Physics.gravity * Spring);
        var projectOnConnection = Vector3.Project(velocityTarget, connection);
        Rigidbody.velocity = (velocityTarget - projectOnConnection) / (1 + Damper * Time.fixedDeltaTime);


    }
}

FrictionJoint3D.cs

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

public class FrictionJoint3D : MonoBehaviour {

    [Range(0,1)]
    public float Friction;

    protected Rigidbody Rigidbody;
    
    void Awake()
    {
        Rigidbody = GetComponent<Rigidbody>();
    }

    void FixedUpdate()
    {
        Rigidbody.velocity = Rigidbody.velocity * (1 - Friction);
        Rigidbody.angularVelocity = Rigidbody.angularVelocity * (1 - Friction);
    }



}

RopeRoot.cs

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

public class RopeRoot : MonoBehaviour {

    public float RigidbodyMass = 1f;
    public float ColliderRadius = 0.1f;
    public float JointSpring = 0.1f;
    public float JointDamper = 5f;
    public Vector3 RotationOffset;
    public Vector3 PositionOffset;

    protected List<Transform> CopySource;
    protected List<Transform> CopyDestination;
    protected static GameObject RigidBodyContainer;

    void Awake()
    {
        if(RigidBodyContainer == null)
            RigidBodyContainer = new GameObject("RopeRigidbodyContainer");

        CopySource = new List<Transform>();
        CopyDestination = new List<Transform>();

        //add children
        AddChildren(transform);
    }

    private void AddChildren(Transform parent)
    {
        for (int i = 0; i < parent.childCount; i++)
        {
            var child = parent.GetChild(i);
            var representative = new GameObject(child.gameObject.name);
            representative.transform.parent = RigidBodyContainer.transform;
            //rigidbody
            var childRigidbody = representative.gameObject.AddComponent<Rigidbody>();
            childRigidbody.useGravity = true;
            childRigidbody.isKinematic = false;
            childRigidbody.freezeRotation = true;
            childRigidbody.mass = RigidbodyMass;

            //collider
            var collider = representative.gameObject.AddComponent<SphereCollider>();
            collider.center = Vector3.zero;
            collider.radius = ColliderRadius;

            //DistanceJoint
            var joint = representative.gameObject.AddComponent<DistanceJoint3D>();
            joint.ConnectedRigidbody = parent;
            joint.DetermineDistanceOnStart = true;
            joint.Spring = JointSpring;
            joint.Damper = JointDamper;
            joint.DetermineDistanceOnStart = false;
            joint.Distance = Vector3.Distance(parent.position, child.position);

            //add copy source
            CopySource.Add(representative.transform);
            CopyDestination.Add(child);

            AddChildren(child);
        }
    }

    public void Update()
    {
        for (int i = 0; i < CopySource.Count; i++)
        {
            CopyDestination[i].position = CopySource[i].position + PositionOffset;
            CopyDestination[i].rotation = CopySource[i].rotation * Quaternion.Euler(RotationOffset);
        }
    }
}

Hi, amazing rope made in unity im having abit of issues with the rope once i scale it down to a small scale to use in a plug as a wire the rope just goes mad and rotates like a mad rope. Hopefully you can help and give some pointers

Thank you

Hello, I'm pretty sure you just have to reduce proportionally the 'Collider Radius' because you adjusted the scale of entire object, while colliders will spawn with the same radius that probably causing the infinite bouncy effect because they repel each other.
Note : Like blender you can operate calculations directly in Inspector fields ; for example → 1 / 2. In this way you'll be able to keep same behaviors.
Besides I might think it's not a good practice, maybe you could modify the script to adjust automatically with the scale.

Hoping that it helped you. Have a good day

Will this work on iOS and Android mobile devices? thanks

Yes, this works on all platforms.

…

On Mon, Jun 10, 2019, 18:41 Michael Levine ***@***.***> wrote: Will this work on iOS and Android mobile devices? thanks — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <https://gist.github.com/ae6ebc115d767da9a5a1e1f70dee27e5?email_source=notifications&email_token=AACTOUVS5RL7MBGJLQZ7WWDPZZ74HA5CNFSM4HWVEFU2YY3PNVWWK3TUL52HS4DFVNDWS43UINXW23LFNZ2KUY3PNVWWK3TUL5UWJTQAFTNY2#gistcomment-2939789>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AACTOURKUKCGJAJLWM3TNILPZZ74HANCNFSM4HWVEFUQ> .

Thank you! One other question: Can the ropes collide with the environment and with each other? And can they be attached to rigid bodies? thanks

Can you help please? The rope is in 4 segments with 4 bones plus a tail bone. Script is on the first bone. No errors showing.
Thank you.

How is the "RotationOffset" being calculated? The rope appears as a zig zag without segments being rotated. If the segments are very small the zig zag may be hard to see.

Hello. Where should the three rows be placed ?