The simplicity of this routine is why I like it so much. You simply run the command and then select a polyline and it displays temporary arrows that show the direction of the polyline. Once you either zoom in or out, or even use **RE** [enter] for a **REGEN**, the temporary arrows will stop displaying.

All credit goes to Luis Esquival and RonJon from the.swamp.org for sharing and editing this routine.

Below – Various polylines have their directions shown

As an extra bonus, this routine works on 3DPOLYLINEs. Even though the arrows aren’t exactly aligned, it is still nice to have a way to show the direction…

~enjoy

;; Original Code by Luis Esquival http://www.theswamp.org/index.php?topic=9441.msg169894#msg169894 ;; Displays the direction of polylines with temporary arrows ;; ;; Modified by RonJonP ;; http://www.theswamp.org/index.php?topic=35706.msg409414#msg409414 (vl-load-com) (defun getarcsegment (cen r fromvertex p2 / a1 a2 d) (if (and fromvertex p2) (progn (setq a1 (angle cen fromvertex) a2 (angle cen p2) ) (if (or (< a1 a2) (equal a1 a2 0.001)) (setq d (* r (- a2 a1))) (setq d (* r (- (+ 6.2831853 a2) a1))) ) ) ;; is a circle (setq d (* r 6.2831853)) ) ) (defun getbulgedata (bulge fromvertex p2 / dir theta beta radio dat) (setq dir (cond ((minusp bulge) -1.0) (t 1.0) ) theta (* 4.0 (atan (abs bulge))) ) (if (> theta pi) (setq theta (- (* 2.0 pi) theta) dir (* -1.0 dir) ) ) (setq theta (/ theta 2.0) radio (abs (/ (distance fromvertex p2) (* 2.0 (abs (sin theta))))) beta (+ (angle fromvertex p2) (* (- (/ pi 2.0) theta) dir)) pc (polar fromvertex beta radio) ) (getarcsegment pc radio p2 fromvertex) ) (defun getlwpolydata (vla_poly / name endparam param closed fromvertex p2 midp bulge vlist) (setq closed (vla-get-closed vla_poly)) (setq endparam (vlax-curve-getendparam vla_poly)) (setq param endparam) (setq i 0) (while (> param 0) (setq param (1- param)) (setq fromvertex (vlax-curve-getpointatparam vla_poly i)) (if (vlax-property-available-p vla_poly 'bulge) (setq bulge (vla-getbulge vla_poly (fix i))) ) (setq nextvertex (vlax-curve-getpointatparam vla_poly (+ i 1))) (setq dis (distance fromvertex nextvertex)) (setq midpt (vlax-curve-getpointatparam vla_poly (+ i 0.5))) (if (and bulge (not (zerop bulge))) (progn (setq bulge (getbulgedata bulge fromvertex nextvertex)) (setq etype "ARC") ) (progn bulge (setq etype "LINE")) ) ;;;;;; (if (not :rcmPrefixArcText) ;;;;;; (setq :rcmPrefixArcText "L=")) (setq vlist (cons (list ;; vertex number (+ i 1) ;; object type etype ;; midpoint midpt ;; start vertex fromvertex ;; ending vertex nextvertex ;; curved or straight length ;;;;;; (if (= eType "ARC") ;;;;;; (strcat ;;;;;; :rcmPrefixArcText ;;;;;; (rtos bulge (rcmd-getUnits-mode) :rcmPrec)) ;;;;;; ;; is straight ;;;;;; (rtos dis (rcmd-getUnits-mode) :rcmPrec)) ) vlist ) ) (setq i (1+ i)) ) (reverse vlist) ) (defun dib_flechdir (lst_dat / unidad angf dirf pfm pf1 pf2 pf3 pf4 pftemp) ;; set arrow length according to screen height ;; to draw the same arrows at any level of zoom (setq unidad (/ (getvar "VIEWSIZE") 15)) (foreach dat lst_dat (setq angf (cadr dat) dirf (caddr dat) pfm (polar (car dat) (+ angf (/ pi 2)) (* unidad 0.3)) pf1 (polar pfm (- angf pi) (/ unidad 2.0)) pf2 (polar pfm angf (/ unidad 2.0)) ) (if (= dirf 1) (setq pf3 (polar pf2 (- angf (/ (* pi 5.0) 6.0)) (/ unidad 4.0)) pf4 (polar pf2 (+ angf (/ (* pi 5.0) 6.0)) (/ unidad 4.0)) ) (setq pftemp pf1 pf1 pf2 pf2 pftemp pf3 (polar pf2 (+ angf (/ pi 6.0)) (/ unidad 4.0)) pf4 (polar pf2 (- angf (/ pi 6.0)) (/ unidad 4.0)) ) ) (if flag_dir (progn ;; draw green arrow ;; when you are changing direction (grdraw pf1 pf2 3) (grdraw pf2 pf3 3) (grdraw pf2 pf4 3) ) (progn ;; draw arrow (grdraw pf1 pf2 4) (grdraw pf2 pf3 4) (grdraw pf2 pf4 4) ) ) ) (setq flag_dir nil) ) ;;; Command for test... (defun c:PLD (/ pol obj pol_data) (setq pol (car (entsel "\nSelect polyline: ")) obj (vlax-ename->vla-object pol) pol_data (getlwpolydata obj) ) (dib_flechdir (setq lst_dat (vl-remove nil (mapcar (function (lambda (i) (if (nth 2 i) (list (nth 2 i) (angle (nth 3 i) (nth 4 i)) 1) ) ) ) pol_data ) ) ) ) (princ) )