This give a point at min z on 3Dpolyline.
(vl-load-com)
(defun c:min_z ( / js obj ename pr pt lst_pt lst_z id_seg nw_pt)
(princ "\nSelect 3DPolylines: ")
(while (null (setq js (ssget '((0 . "POLYLINE") (-4 . "&") (70 . 8)))))
(princ "\nObjects not valid!")
)
(repeat (setq n (sslength js))
(setq
obj (ssname js (setq n (1- n)))
ename (vlax-ename->vla-object obj)
pr -1
lst_pt nil
)
(repeat (if (zerop...