/** * From the point of view of an observer located outside the polygon, only a continuous subset of * the polygon's edges can be seen defining a line-of-sight. This method finds the first and last * vertices that is in the line-of-sight. * * @param observer the coordinates of the observer. Not modified. * @return the coordinates in order of the first and last vertices in the line-of-sight or * {@code null} if this method failed. Modified. * @throws ReferenceFrameMismatchException if {@code observer} and {@code this} are not expressed * in the same reference frame. * @see #lineOfSightVertices(Point2DReadOnly) */ default FramePoint2DBasics[] lineOfSightVertices(FramePoint2DReadOnly observer) { checkReferenceFrameMatch(observer); return lineOfSightVertices((Point2DReadOnly) observer); }