Uppermgmt.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Runtime.InteropServices;
using System.Linq;

/*
From Meraki VR Experience : https://design.embracingearth.space/2018/12/13/meraki-1-o/
This is a modified script which controls the Camera Dynamics: 
In Meraki 1.0 WebVR Experience, you can switch between two Camera Dynamics. 
One of the camera dynamics is such a way to respresent immersion of looking inside oneself. 
The Rotation from VR Headset is converted into a lookat heart object, so when user rotates their head(in VR) -
instead of rotating normally(from a point) as it should, the camera rotates around the object(heart) -lookAT

Original Script is from Mozilla WebVR https://github.com/MozillaReality/unity-webxr-export/tree/master/Assets/WebXR/Scripts
This Script is modified WebVRCamera.cs and will not work independently but needs to be combined with the repo.
In Place WebVRCamera.cs /// To Note, the effect wont be visible if testing inside Unity environment as scripts calls through webxrapi 
and will only work perfectly in builds. Unity test environment seems to override the api when testing with headset inside Unity.
*/
public class Uppermgmt : MonoBehaviour
{
    private const float Y_ANGLE_MIN = 0.0f;
    private const float Y_ANGLE_MAX = 50.0f;
    //Adding the object you want the camera to rotate around - lookAt.
    public Transform lookAt;
    public Transform camTransform;
    public float distance = 10.0f;

    private float currentX = 0.0f;
    private float currentY = 0.0f;
    private float sensitivityX = 4.0f;
    private float sensitivityY = 1.0f;
	
	private Matrix4x4 sitStand;

    private Camera cameraMain, cameraL, cameraR;
    public bool vrActive = true;
	
	
	
	
	
    [DllImport("__Internal")]
    private static extern void PostRender();
	
    private IEnumerator endOfFrame()
    {
        // Wait until end of frame to report back to WebVR browser to submit frame.
        yield return new WaitForEndOfFrame();
        PostRender ();
	}
	
	 void OnEnable()
    {	 
        WebVRManager.Instance.OnVRChange += onVRChange;
        WebVRManager.Instance.OnHeadsetUpdate += onHeadsetUpdate;
        
        cameraMain = GameObject.Find("CameraMain").GetComponent<Camera>();
        cameraL = GameObject.Find("CameraL").GetComponent<Camera>();
        cameraR = GameObject.Find("CameraR").GetComponent<Camera>();

        cameraMain.transform.Translate(new Vector3(0, WebVRManager.Instance.DefaultHeight, 0));
    }

    private void Start()
    {  
        camTransform = transform;
		
    }

	   void Update()
    { 
	   
	   {
        if (vrActive)
        {   
            cameraMain.enabled = false;
            cameraL.enabled = true;
            cameraR.enabled = true;
	   } 
	    
        else
        {
            cameraMain.enabled = true;
            cameraL.enabled = false;
            cameraR.enabled = false;
        }
	   } 
        #if !UNITY_EDITOR && UNITY_WEBGL
        // Calls Javascript to Submit Frame to the browser WebVR API.
        StartCoroutine(endOfFrame());
        #endif
    } 

	   private void onVRChange(WebVRState state)
    {
        vrActive = state == WebVRState.ENABLED;
    }
	
	private void onHeadsetUpdate (
        Matrix4x4 leftProjectionMatrix,
        Matrix4x4 leftViewMatrix,
        Matrix4x4 rightProjectionMatrix,
        Matrix4x4 rightViewMatrix,
        Matrix4x4 sitStandMatrix)
    {
        if (vrActive)
        {
            SetTransformFromViewMatrix (leftViewMatrix * sitStandMatrix.inverse);
            cameraL.projectionMatrix = leftProjectionMatrix;
            SetTransformFromViewMatrix (rightViewMatrix * sitStandMatrix.inverse);
            cameraR.projectionMatrix = rightProjectionMatrix;
        }
    }
	
    private void SetTransformFromViewMatrix(Matrix4x4 webVRViewMatrix)
    {
	    Matrix4x4 trs = TransformViewMatrixToTRS(webVRViewMatrix);
		
        Vector3 dir = new Vector3(0, 0, -distance);
        Quaternion rotation = Quaternion.LookRotation(trs.GetColumn(2), trs.GetColumn(1));
        //Main Change done for Meraki VR experience >> 
        //This Links the Rotation of VR headset to an inverted LookAt.
        camTransform.position = lookAt.position + rotation * dir;
        camTransform.LookAt(lookAt.position);
    }

/* Orignal Code from Mozilla WebVR which acts on normal camera dynamics , Linked to VR headset. 
    In Meraki VR experience - Another Script containing this structure on another camera exists and this camera dynamic can 
    be switched between, to experience both.

      // According to https://answers.unity.com/questions/402280/how-to-decompose-a-trs-matrix.html
    private void SetTransformFromViewMatrix(Transform transform, Matrix4x4 webVRViewMatrix)
    {
        Matrix4x4 trs = TransformViewMatrixToTRS(webVRViewMatrix);
        transform.localPosition = trs.GetColumn(3);
        transform.localRotation = Quaternion.LookRotation(trs.GetColumn(2), trs.GetColumn(1));
        transform.localScale = new Vector3(
            trs.GetColumn(0).magnitude,
            trs.GetColumn(1).magnitude,
            trs.GetColumn(2).magnitude
        );
    }
*/
	
	  // According to https://forum.unity.com/threads/reproducing-cameras-worldtocameramatrix.365645/#post-2367177
    private Matrix4x4 TransformViewMatrixToTRS(Matrix4x4 openGLViewMatrix)
    {
        openGLViewMatrix.m20 *= -1;
        openGLViewMatrix.m21 *= -1;
        openGLViewMatrix.m22 *= -1;
        openGLViewMatrix.m23 *= -1;
        return openGLViewMatrix.inverse;
    }
	
	
}