code: public void rotate(Quaternion rotation) {
  		Transform3D m = new Transform3D();
  		m.setRotation(rotation);
  		m.transform(this.getSegmentVector());
  		this.getSegmentVector().normalize();
  	}
docs: Rotate the segment around its pivot point.
  The pivot point is the first point of the segment.
  
  @param rotation the rotation.