autolisp 里怎么获取polyline的每个点的坐标?

;———取线的顶点坐标——————–;
(setq wfx (entget(car(entsel”\n请选择范围线:”))) i 0 ptt-list ‘() )
(if (= (cdr(assoc 0 wfx)) “LWPOLYLINE”)
(progn
(repeat(length wfx)
(setq pt-list (nth i wfx))
(if (= (car pt-list) 10)
(progn
(setq ptt (cdr pt-list))
(setq ptt-list (cons ptt ptt-list))
) )
(progn
(setq i (1+ i)) ))))
;;;;;;;;;;;;顶点坐标结束‘;;;;;;;;;;;;
顶点的坐标保存在PTT-LISt中…..