protected virtual void OnTrackingLost()
    {
        var rendererComponents   = GetComponentsInChildren <Renderer>(true);
        var colliderComponents   = GetComponentsInChildren <Collider>(true);
        var canvasComponents     = GetComponentsInChildren <Canvas>(true);
        PlayOnStateChange player = GetComponentInChildren <PlayOnStateChange>();


        // Disable rendering:
        foreach (var component in rendererComponents)
        {
            component.enabled = false;
        }

        // Disable colliders:
        foreach (var component in colliderComponents)
        {
            component.enabled = false;
        }

        // Disable canvas':
        foreach (var component in canvasComponents)
        {
            component.enabled = false;
        }


        player.Terminate();
    }