Unity

This guide provides detailed instructions to download, set up, and run the AMFITRACK SteamVR driver in Unity 6.

This guide is written with the express purpose of being simple and only covers how to recive pose data (not buttons and analog inputs). However there are many other ways to connect to the AMFITRACK SteamVR driver in Unity. Since the AMFITRACK driver uses steamVR, any method of reading data from steamVR should work. For futher information consult the official steamVR github.

Prerequisites

Before you begin, ensure the following prerequisites are met:

• Unity: Download and install Unity from the official Unity site.

• AMFITRACK SteamVR driver: Follow the installation instructions in the AMFITRACK SteamVR documentation.

Unity Setup

Follow these steps to set up Unity, install the SteamVR plugin, and add a Tracked Pose Driver. These instructions are based on Unity 6.

Create a New Unity Project

1. Open Unity Hub and click New Project.

2. Select the 3D template.

3. Name your project (e.g., SteamVR_Setup) and click Create.

4. This guide has been tested with Unity 6.

Install the SteamVR Plugin

1. Open the Unity Asset Store:

   • Navigate to Window > Asset Store in Unity or visit the Unity Asset Store online.

2. Search for SteamVR Plugin:

   • Look for “SteamVR Plugin” by Valve Corporation.

3. Download and Import:

   • Click Download, then Import to add the plugin to your Unity project.

   • Ensure all required assets are selected in the import dialog and click Import.

4. Configure the Project:

   • After importing, Unity may prompt you to configure OpenVR settings.

   • Accept the changes, such as enabling Virtual Reality Supported in XR Settings.

Configure XR Plug-in Management

1. Open the Project Settings:

   • Go to Edit > Project Settings.

2. Enable XR Plug-in Management:

   • In the Project Settings window, navigate to the XR Plug-in Management section.

   • Under the PC, Mac & Linux Standalone tab, enable OpenXR.

3. Set the OpenXR Runtime to SteamVR:

   • Still under the OpenXR settings, locate Play Mode OpenXR Runtime.

   • Set it to SteamVR to ensure compatibility with the SteamVR runtime.

Add AMFITRACK Unity VR script

The AMFITRACK Steam VR driver reports poses in a right-handed y-axis up cordinate. However, unity handles poses in a left-handed y-axis up cordinate. The Following steps will add the nessary code to transform poses from the Steam VR format into Unity format.

1. Create a MonoBehaviour Script:

   • Select Assets > Create > Scripting > MonoBehaviour Script.

2. Name the MonoBehaviour Script:

   • Type in the name AMFITRACK_UNITY_VR_Script (any other name of your choice should also work, but the guide will use this name when refering to this MonoBehaviour Script).

3. Edit MonoBehaviour Script:

   • Open AMFITRACK_UNITY_VR_Script in a editor of your choice.

   • Replace the contents of AMFITRACK_UNITY_VR_Script with the code snippet below (using copy and paste).

   using System;
   using System.CodeDom.Compiler;
   using System.Collections.Specialized;
   using System.Diagnostics;
   using UnityEngine;
   using Valve.VR;
   
   struct pose
   {
      public Vector3 position;
      public Quaternion orientation;
   };
   
   public class AMFITRACK_UNITY_VR_Script : MonoBehaviour
   {
      public uint DeviceIndex = 0;
   
      void Update()
      {
         pose controller_pose = getUnityPose(DeviceIndex);
         transform.SetPositionAndRotation(controller_pose.position, controller_pose.orientation);
      }
      pose getUnityPose(uint ID)
      {
         pose output;
         output.position = new Vector3(0, 0, 0);
         output.orientation = new Quaternion(0, 0, 0, 1);
   
         TrackedDevicePose_t[] poses = new TrackedDevicePose_t[OpenVR.k_unMaxTrackedDeviceCount];
         OpenVR.System.GetDeviceToAbsoluteTrackingPose(ETrackingUniverseOrigin.TrackingUniverseStanding, 0, poses);
   
         if (OpenVR.System != null && ID < OpenVR.k_unMaxTrackedDeviceCount && (OpenVR.System.GetTrackedDeviceClass(ID) == ETrackedDeviceClass.Controller || OpenVR.System.GetTrackedDeviceClass(ID) == ETrackedDeviceClass.GenericTracker || OpenVR.System.GetTrackedDeviceClass(ID) == ETrackedDeviceClass.HMD))
         {
               var poseMatrix = poses[ID].mDeviceToAbsoluteTracking;
               Vector3 position_raw = new Vector3(poseMatrix.m3, poseMatrix.m7, poseMatrix.m11);
               output.position = new Vector3(
                  position_raw.x,
                  position_raw.y,
                  -position_raw.z
                  );
               Quaternion orientation_raw = Quaternion_FromMatrix(poseMatrix);
               output.orientation = new Quaternion(
                     -orientation_raw.x,
                     -orientation_raw.y,
                     orientation_raw.z,
                     orientation_raw.w);
         }
         return output;
      }
      Quaternion Quaternion_FromMatrix(HmdMatrix34_t matrix)
      {
         float w = Mathf.Sqrt(Mathf.Max(0, 1 + matrix.m0 + matrix.m5 + matrix.m10)) / 2;
         float x = Mathf.Sqrt(Mathf.Max(0, 1 + matrix.m0 - matrix.m5 - matrix.m10)) / 2;
         float y = Mathf.Sqrt(Mathf.Max(0, 1 - matrix.m0 + matrix.m5 - matrix.m10)) / 2;
         float z = Mathf.Sqrt(Mathf.Max(0, 1 - matrix.m0 - matrix.m5 + matrix.m10)) / 2;
   
         x = Mathf.Sign(x * (matrix.m9 - matrix.m6)) * x;
         y = Mathf.Sign(y * (matrix.m2 - matrix.m8)) * y;
         z = Mathf.Sign(z * (matrix.m4 - matrix.m1)) * z;
   
         return new Quaternion(x, y, z, w);
      }
   }
   

Set Up an Object with the Steam VR script

1. Create a 3D Object:

   • In the Hierarchy window, right-click and select 3D Object > Cube (or any object of your choice).

2. Add the AMFITRACK_UNITY_VR_Script Component:

   • Select the object in the Hierarchy.

   • In the Inspector, click Add Component.

   • Search for and select AMFITRACK_UNITY_VR_Script.

3. Set the Device Index:

• The Device Index determines which piece of HW the 3D object will follow to what piece of hardware you wish your 3D object to follow.

• (For this guide it is NOT recommended using Generic Tracker SRC as it behaves very differently from the Controllers and Trackers.)

Device Index	AMFITRACK ID	device-type
0	N/A	HMD
16	2	Left Controller
17	3	Right Controller
18	4	Generic Tracker 01
19	5	Generic Tracker 02
20	6	Generic Tracker 03
21	7	Generic Tracker 04
22	9	HMD Src Tracker

Run the Scene

1. Connect your VR headset and launch SteamVR.

2. In Unity, press the Play button to test your scene.

3. The object with the AMFITRACK_UNITY_VR_Script should now follow the motion of your VR device.

Troubleshooting

• SteamVR Plugin Not Found:

  • Ensure you are logged into the Unity Asset Store and have an active internet connection.

• Tracked Pose Driver Does Not Work:

  • Verify the Device and Pose Source settings in the Tracked Pose Driver component.

  • Ensure SteamVR is running, and your VR headset is properly connected.

Additional Notes

• These instructions are specific to Unity 6. If you are using a different version, some steps or UI elements may differ.

• For more information, refer to the official Unity documentation.