code: public void rotateToFront() {
          GVRTransform transform = mSceneRootObject.getTransform();
          transform.setRotation(1, 0, 0, 0);
          transform.rotateByAxisWithPivot(-frontFacingRotation + 180, 0, 1, 0, 0, 0, 0);
      }
docs: Rotate root widget to make it facing to the front of the scene