PortalCamera.cs

            var playerToEntrance = PortalEntrance.position - PlayerCamera.transform.position;
            Debug.Log(playerToEntrance);
            var renderCenter = originalPosition - playerToEntrance;

            var leftEyeOffset = InputTracking.GetLocalPosition((VRNode)0);
            var leftEyeRotation = InputTracking.GetLocalRotation((VRNode)0);

            var rightEyeOffset = InputTracking.GetLocalPosition((VRNode)1);
            var rightEyeRotation = InputTracking.GetLocalRotation((VRNode)1);

            Debug.Log("left eye: " + leftEyeRotation.eulerAngles);
            Debug.Log("right eye: " + rightEyeRotation.eulerAngles);

            transform.position = renderCenter - leftEyeOffset;
            transform.rotation = leftEyeRotation;
            cameraForPortal.projectionMatrix = HMDMatrix4x4ToMatrix4x4(SteamVR.instance.hmd.GetProjectionMatrix(Valve.VR.EVREye.Eye_Left, VrEye.nearClipPlane, VrEye.farClipPlane, Valve.VR.EGraphicsAPIConvention.API_DirectX));
            cameraForPortal.targetTexture = leftEyeRenderTexture;
            cameraForPortal.Render();
            material.SetTexture("_LeftEyeTexture", leftEyeRenderTexture);

            transform.position = renderCenter - rightEyeOffset;
            transform.rotation = rightEyeRotation;
            cameraForPortal.projectionMatrix = HMDMatrix4x4ToMatrix4x4(SteamVR.instance.hmd.GetProjectionMatrix(Valve.VR.EVREye.Eye_Right, VrEye.nearClipPlane, VrEye.farClipPlane, Valve.VR.EGraphicsAPIConvention.API_DirectX));
            cameraForPortal.targetTexture = rightEyeRenderTexture;
            cameraForPortal.Render();
            material.SetTexture("_RightEyeTexture", rightEyeRenderTexture);