Htc Vive can't get axis from touchpad input

Questions & Answers
1

Hi,

I am trying to use the htc vive touchpad to control the speed the player is moving at by sliding your thumbs up and down the touchpad.

I have created a walking actionset with a vector2 action named Walk

Then, I bind it to the my left vive controller touchpad’s position

153164-binding.png
153164-binding.png1897×832 129 KB

I created an empty object named ActivateWalking and load a script “SteamVR_Activate Action Set On Load” in it. And i load a script named “MovementController” into my Controller(left) under CameraRig under Player

153165-script-location.png
153165-script-location.png1920×1031 238 KB

I tried two ways of getting the axis

  1. Call the AddOnChangeListener

    using System.Collections;
    using System.Collections.Generic;
    using UnityEngine;
    using UnityEngine.XR;
    using Valve.VR;
    using Valve.VR.InteractionSystem;

    public static class ExtensionMethods
    {
    public static float Remap(this float value, float from1, float to1, float from2, float to2)
    {
    return (value - from1) / (to1 - from1) * (to2 - from2) + from2;
    }
    }

    public class MovementController : MonoBehaviour
    {
    public SteamVR_Action_Vector2 walkAction;
    public Valve.VR.InteractionSystem.Hand hand;
    public float speed;
    public GameObject player;

     private void OnEnable()
 {
 	if(hand == null)
 		hand = this.GetComponent<Valve.VR.InteractionSystem.Hand>();

 	if(walkAction == null)
 	{
 		Debug.LogError("<b>[SteamVR.Interaction]</b> No walk action assigned", this);
 		return;
 	}

 	walkAction.AddOnChangeListener(OnWalkActionChange, hand.handType);
 }

 private void OnDisable()
 {
 	if (walkAction != null)
 		walkAction.RemoveOnChangeListener(OnWalkActionChange, hand.handType);
 }

 private void OnWalkActionChange(SteamVR_Action_Vector2 actionIn, SteamVR_Input_Sources inputSource,Vector2 axis, Vector2 delta)
 {
 	
 	Debug.Log($"Coordinate obtained = {delta.y}");
 	float sf = delta.y;
 	if (Mathf.Clamp(sf, -1, 1) == sf)
 	{
 		sf = sf.Remap(-1, 1, 0, 2);
 		Walk(sf);
 	}
 }

 private void Walk(float speedFactor)
 {
 	Quaternion rotation;

 	InputDevice hmd = InputDevices.GetDeviceAtXRNode(XRNode.CenterEye);
 	if (hmd.isValid)
 	{
 		if (hmd.TryGetFeatureValue(CommonUsages.centerEyeRotation, out rotation))
 		{
 			Debug.Log("rotation is " + rotation);
 			player.transform.position += rotation * Vector3.forward * speed * speedFactor * Time.deltaTime;
 		}
 	}
 }

    }

  2. To use SteamVR_Input.GetVector2 in updates

    using System.Collections;
    using System.Collections.Generic;
    using UnityEngine;
    using UnityEngine.XR;
    using Valve.VR;
    using Valve.VR.InteractionSystem;

    public static class ExtensionMethods
    {
    public static float Remap(this float value, float from1, float to1, float from2, float to2)
    {
    return (value - from1) / (to1 - from1) * (to2 - from2) + from2;
    }
    }

    public class MovementController : MonoBehaviour
    {
    public SteamVR_Action_Vector2 walkAction;
    public Valve.VR.InteractionSystem.Hand hand;
    public float speed;
    public GameObject player;

     private void OnEnable()
 {
 	if(hand == null)
 		hand = this.GetComponent<Valve.VR.InteractionSystem.Hand>();

 }



 // Update is called once per frame
 private void Update()
 {
 	Vector2 sf = SteamVR_Input.GetVector2("walking", "Walk", hand.handType);
 	float speedFactor = sf.y;
 	speedFactor = speedFactor.Remap(-1, 1, 0, 2);

 	Quaternion rotation;

 	InputDevice hmd = InputDevices.GetDeviceAtXRNode(XRNode.CenterEye);
 	if (hmd.isValid)
 	{
 		if(hmd.TryGetFeatureValue(CommonUsages.centerEyeRotation,out rotation))
 		{
 			Debug.Log("rotation is " + rotation);
 			if (Input.GetKey(KeyCode.W))
 				player.transform.position += rotation * Vector3.forward * speed * speedFactor * Time.deltaTime;
 		}
 	}

 }

    }

They both give me an error of

NullReferenceException: Object reference not set to an instance of an object

May someone tell me how could I fix that?
Thank you.

2

When I call “AddOnChangeListener”, is there anything that I should put for “Vector2 axis” of the “OnWalkActionChange” function?

3

When using SteamVRInput in unity it defines and compiles code special for your Actions and Actionsets.

You can then do

SteamVR_Actions.default_Throttle.GetAxis(SteamVR_Input_Sources.Any) //axis
SteamVR_Actions.default_Fire.GetState(SteamVR_Input_Sources.Any) //button

Where default_Fire is the name of the Actionset_Action.
You set the definitions in Window->SteamVR Input and then you have to bind them in the steam UI.