_controlNodeTouch(event) {
    this.selectionHandler.unselectAll();
    this.lastTouch = this.body.functions.getPointer(event.center);
    this.lastTouch.translation = Object.assign({}, this.body.view.translation); // copy the object
  }
the touch is used to get the position of the initial click
@param {Event}  event   The event
@private