public void Update()
    {
        List <XRDetectedImageTarget> detectedTargets = xr_.GetDetectedImageTargets();

        SetStatusText(detectedTargets);
        foreach (XRDetectedImageTarget target in detectedTargets)
        {
            if (targetToCallback_.ContainsKey(target.name))
            {
                OnImageTargetDetected cb = targetToCallback_[target.name];
                if (cb != null)
                {
                    cb.Invoke(target);
                }
            }
        }
    }
 public void SetCallbackOnTarget(string targetName, OnImageTargetDetected callback)
 {
     targetToCallback_.Add(targetName, callback);
 }