void OnDestroy()
{
if (isFacetrackingInitialized && sensorData != null && sensorData.sensorInterface != null)
{
// finish face tracking
sensorData.sensorInterface.FinishFaceTracking();
}
// // clean up
// Resources.UnloadUnusedAssets();
// GC.Collect();
isFacetrackingInitialized = false;
instance = null;
}