The main principle of Wing Chun is that both sides of the body contribute power to the center line in a triangular or arrowhead fashion. Torso rotation, turning or swinging for reach or power generation is not part of the framework of the style because it removes one side of the body from contributing power to center, requires a wind up telegraphing motion and limits your forward extension because turning prevents you from moving forward. In order for this framework to work you have to be able and willing to move into the opponent’s space if necessary at an angle to the original line of attack.