We have a series of VG onboarding tasks to show how to tackle different practical use cases using VirtualGrasp in a VR application. In VirtualGrasp SDK, they are packed in VirtualGrasp\Scenes\onboarding.

Task Description

Interaction behaviors wanted

  • Initially the valve is a free moving physical object with Articulation Body component.
  • When user grasp and moves it to a target desired position (indicated by the transparent valve), it will be assembled to this position and becomes a rotatable valve around the center.
  • When user grasp the assembled valve and pull out to certain distance, the valve will become dissembled and freely movable again.

Tips for VR developers

  • This task is mainly to showcase VirtualGrasp’s support on interaction with ArticulationBody.


In VirtualGrasp SDK, we packed the solution of this task in VirtualGrasp/Scenes/onboarding.


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

 * AssembleArticulationBody shows as a tutorial on how to use VG to
 * assemble and dissemble objects through Unity's ArticulationBody.
public class AssembleArticulationBody : MonoBehaviour
    public Transform m_newParent = null;
    public Transform m_desiredPose = null;
    public float m_assembleDistance = 0.05f;
    public float m_disassembleDistance = 0.5f;

    public ArticulationJointType m_jointType = ArticulationJointType.FixedJoint;
    public bool m_matchAnchors = true;
    public Vector3 m_anchorPosition = Vector3.zero;
    public Vector3 m_anchorRotation = Vector3.zero;
    public Vector3 m_parentAnchorPosition = Vector3.zero;
    public Vector3 m_parentAnchorRotation = Vector3.zero;

    private ArticulationBody m_this_ab;
    private ArticulationBody m_parent_ab;

    private float timeAtDisassemble = 0.0F;
    private float assembleDelay = 1.0F;

    void Start()
        gameObject.TryGetComponent<ArticulationBody>(out m_this_ab);
        if (m_newParent != null)

            if(!m_newParent.TryGetComponent<ArticulationBody>(out m_parent_ab))
                Debug.LogWarning("New parent " + m_newParent.name + " should have Articulation Body component, will add one in script");
                m_parent_ab = m_newParent.gameObject.AddComponent<ArticulationBody>();
            Debug.LogError("Need to specify assembling New Parent!");

    void Update()

    void assembleArticulationBody()
        if(m_this_ab == null || m_parent_ab == null)
            Debug.LogError("Object do no have articulation body, so can't do articulation body based assembling!");

        if ((Time.realtimeSinceStartup - timeAtDisassemble) > assembleDelay
            && (m_desiredPose.position - transform.position).magnitude < m_assembleDistance
            && transform.parent != m_newParent)
            transform.SetPositionAndRotation(m_desiredPose.position, m_desiredPose.rotation);
            m_this_ab.jointType = m_jointType;
#if UNITY_2021_2_OR_NEWER
            m_this_ab.matchAnchors = m_matchAnchors;
            m_this_ab.computeParentAnchor = m_matchAnchors;
            m_this_ab.anchorPosition = m_anchorPosition;
            m_this_ab.anchorRotation = Quaternion.Euler(m_anchorRotation);
            m_this_ab.parentAnchorPosition = m_parentAnchorPosition;
            m_this_ab.parentAnchorRotation = Quaternion.Euler(m_parentAnchorRotation);

    void dissembleArticluationBody()
        foreach (VG_HandStatus hand in VG_Controller.GetHands())
            if (hand.m_selectedObject == transform && hand.IsHolding() && transform.parent == m_newParent)
                VG_Controller.GetSensorPose(hand.m_avatarID, hand.m_side, out Vector3 sensor_pos, out Quaternion sensor_rot);
                if ((sensor_pos - hand.m_hand.position).magnitude > m_disassembleDistance ) 
                    timeAtDisassemble = Time.realtimeSinceStartup;