@Test
  public void testIntersectionOfLineWithLineSegmentWhereIntersectionIsNotPartOfLineSegment() {
    Point3D p2 = new Point3D(8, 2, 6);
    Point3D p3 = new Point3D(0, 9, 1);
    Point3D p4 = new Point3D(5, 7, 2);
    Point3D intersect;

    Line3D l1 = new Line3D(p2, p3);
    Line3D l2 = new Line3D(p2, p4);
    Line3DSegment ls1 = new Line3DSegment(l2.getPoint(0.01), p4);

    intersect = Geometry3DUtils.intersectionOfTwoLines(l1, ls1);
    assertEquals(null, intersect);
  }
  @Test
  public void testIntersectionOfLineWithLineSegmentWhereIntersectionsExists() {
    Point3D p1 = new Point3D(3, 4, 5);
    Point3D p2 = new Point3D(8, 2, 6);
    Point3D p3 = new Point3D(0, 9, 1);
    Point3D intersect;

    Line3D l1 = new Line3D(p2, p3);
    Line3D l2 = new Line3D(p1, p2);
    Line3DSegment ls1 = new Line3DSegment(p1, l2.getPoint(3));

    intersect = Geometry3DUtils.intersectionOfTwoLines(l1, ls1);
    assertEquals(p2, intersect);
  }