void OnControllerPinchStay(InteractionController controller)
{
var index = controller.isRight ? 1 : 0;
var pinchPos = controller.GetPinchPosition();
_grabCurPositions[index] = pinchPos;
}
void OnControllerPinchBegin(InteractionController controller)
{
_pinchBeginControllers.Add(controller);
// Debug.Log("pinch begin " + (controller.isLeft ? "left" : "right"));
var index = controller.isRight ? 1 : 0;
var pinchPos = controller.GetPinchPosition();
_grabPrevPositions[index] = _grabCurPositions[index] = pinchPos;
}