Trovare ed eliminare linee e polilinee di lunghezza zero

Testo semplice, niente di nascosto. Copialo in un file chiamato cxzerolen.lsp oppure scaricalo.

;;; ============================================================================
;;; CXZEROLEN - Find and delete zero-length lines and polylines
;;; Version 1.0.0
;;; CADXChange LISP tools - https://cadxchange.net/resources/lisp/cxzerolen
;;; Tested in: AutoCAD (full version). Other programs that run AutoLISP may work but are not tested.
;;; Copyright (c) CADXChange. Free for personal and commercial use; do not resell or
;;; republish it as a collection. Terms: https://cadxchange.net/legal/lisp-terms
;;; ============================================================================

;; The lines, arcs and polylines in NAMES that are shorter than TOL. With DEL true they are erased as well.
;; Returns the entity names found.
(defun cx:zerolen-run (names tol del / out len)
  (foreach e names
    (setq len (cx:ent-length (entget e)))
    (if (and len (/= (cx:dxf 0 (entget e)) "CIRCLE") (< len tol))
      (setq out (cons e out))))
  (setq out (reverse out))
  (if del (foreach e out (entdel e)))
  out)

(defun c:CXZEROLEN ( / *error* cx:sv ss tol found)
  (setq *error* cx:err)
  (setq ss (ssget "X" (list '(0 . "LINE,ARC,LWPOLYLINE") (cons 410 (getvar "CTAB")))))
  (if ss
    (progn
      (setq tol (cx:ask-real "Objects shorter than this count as zero length" 0.0001))
      (setq found (cx:zerolen-run (cx:ss->list ss) tol nil))
      (cond
        ((null found) (princ "\nNo zero-length objects found."))
        ((= (cx:ask-kw (strcat (itoa (length found)) " found. Action") "Delete Select" "Select") "Delete")
         (cx:start '(("CMDECHO" . 0)))
         (cx:zerolen-run found tol T)
         (princ (strcat "\n" (itoa (length found)) " object(s) deleted."))
         (cx:end))
        (T
         (sssetfirst nil (cx:list->ss found))
         (princ (strcat "\n" (itoa (length found)) " object(s) selected."))))))
  (princ))


;;; ---- Shared helpers (used by the command above; identical in every CADXChange tool) ----

;; The vertices of an LWPOLYLINE entity list as ((x y bulge start-width end-width) ...).
(defun cx:lw-verts (ed / out cur)
  (foreach g ed
    (cond
      ((= (car g) 10)
       (if cur (setq out (cons cur out)))
       (setq cur (list (cadr g) (caddr g) 0.0 0.0 0.0)))
      ((and cur (= (car g) 40)) (setq cur (list (nth 0 cur) (nth 1 cur) (nth 2 cur) (cdr g) (nth 4 cur))))
      ((and cur (= (car g) 41)) (setq cur (list (nth 0 cur) (nth 1 cur) (nth 2 cur) (nth 3 cur) (cdr g))))
      ((and cur (= (car g) 42)) (setq cur (list (nth 0 cur) (nth 1 cur) (cdr g) (nth 3 cur) (nth 4 cur))))))
  (if cur (setq out (cons cur out)))
  (reverse out))

;; The arc a bulge makes between P1 and P2 as (center-x center-y radius start-angle sweep), or nil for a straight segment.
;; The sweep is signed: positive turns counter-clockwise.
(defun cx:bulge-arc (p1 p2 b / theta dx dy len nx ny d ccx ccy)
  (if (< (abs b) 1e-9)
    nil
    (progn
      (setq theta (* 4.0 (atan b))
            dx    (- (car p2) (car p1))
            dy    (- (cadr p2) (cadr p1))
            len   (sqrt (+ (* dx dx) (* dy dy))))
      (if (< len 1e-12)
        nil
        (progn
          (setq nx  (/ (- dy) len)
                ny  (/ dx len)
                d   (/ (/ len 2.0) (/ (sin (/ theta 2.0)) (cos (/ theta 2.0))))
                ccx (+ (/ (+ (car p1) (car p2)) 2.0) (* nx d))
                ccy (+ (/ (+ (cadr p1) (cadr p2)) 2.0) (* ny d)))
          (list ccx ccy (/ len (* 2.0 (sin (/ (abs theta) 2.0))))
                (atan (- (cadr p1) ccy) (- (car p1) ccx)) theta))))))

;; The number of segments of a polyline with N vertices.
(defun cx:seg-count (n closed)
  (if closed n (1- n)))

;; A polyline as a list of (x y) points; arcs are cut into short straight pieces.
(defun cx:lw-points (verts closed / out i n a v1 v2 k steps ang)
  (setq i 0 n (length verts))
  (repeat (cx:seg-count n closed)
    (setq v1  (nth i verts)
          v2  (nth (rem (1+ i) n) verts)
          a   (cx:bulge-arc v1 v2 (nth 2 v1))
          out (cons (list (car v1) (cadr v1)) out))
    (if a
      (progn
        (setq steps (max 4 (fix (/ (abs (nth 4 a)) 0.15))) k 1)
        (while (< k steps)
          (setq ang (+ (nth 3 a) (* (nth 4 a) (/ (float k) steps)))
                out (cons (list (+ (car a) (* (nth 2 a) (cos ang))) (+ (cadr a) (* (nth 2 a) (sin ang)))) out)
                k   (1+ k)))))
    (setq i (1+ i)))
  (if (not closed)
    (setq out (cons (list (car (last verts)) (cadr (last verts))) out)))
  (reverse out))

(defun cx:dxf (code ed)
  (cdr (assoc code ed)))

;; An object as a list of (x y) points; circles and ellipses are cut into 120 pieces, arcs into short pieces.
;; Returns nil for an object it does not know.
(defun cx:ent-points (ed / type ctr r a1 a2 k pts ratio ang maj steps)
  (setq type (cx:dxf 0 ed))
  (cond
    ((= type "LWPOLYLINE") (cx:lw-points (cx:lw-verts ed) (= 1 (logand 1 (cx:dxf 70 ed)))))
    ((= type "LINE")
     (list (list (car (cx:dxf 10 ed)) (cadr (cx:dxf 10 ed))) (list (car (cx:dxf 11 ed)) (cadr (cx:dxf 11 ed)))))
    ((= type "CIRCLE")
     (setq ctr (cx:dxf 10 ed) r (cx:dxf 40 ed) k 0)
     (repeat 120
       (setq ang (* 2.0 pi (/ k 120.0))
             pts (cons (list (+ (car ctr) (* r (cos ang))) (+ (cadr ctr) (* r (sin ang)))) pts)
             k   (1+ k)))
     (reverse pts))
    ((= type "ARC")
     (setq ctr (cx:dxf 10 ed) r (cx:dxf 40 ed) a1 (cx:dxf 50 ed) a2 (cx:dxf 51 ed))
     (if (<= a2 a1) (setq a2 (+ a2 (* 2.0 pi))))
     (setq steps (max 8 (fix (/ (- a2 a1) 0.05))) k 0)
     (repeat (1+ steps)
       (setq ang (+ a1 (* (- a2 a1) (/ (float k) steps)))
             pts (cons (list (+ (car ctr) (* r (cos ang))) (+ (cadr ctr) (* r (sin ang)))) pts)
             k   (1+ k)))
     (reverse pts))
    ((= type "ELLIPSE")
     (setq ctr (cx:dxf 10 ed) maj (cx:dxf 11 ed) ratio (cx:dxf 40 ed) a1 (cx:dxf 41 ed) a2 (cx:dxf 42 ed))
     (if (<= a2 a1) (setq a2 (+ a2 (* 2.0 pi))))
     (setq k 0)
     (repeat 121
       (setq ang (+ a1 (* (- a2 a1) (/ k 120.0)))
             pts (cons (list (+ (car ctr) (* (car maj) (cos ang)) (* (- (cadr maj)) ratio (sin ang)))
                             (+ (cadr ctr) (* (cadr maj) (cos ang)) (* (car maj) ratio (sin ang))))
                       pts)
             k   (1+ k)))
     (reverse pts))))

(defun cx:lw-length (verts closed / total i n a v1 v2)
  (setq total 0.0 i 0 n (length verts))
  (repeat (cx:seg-count n closed)
    (setq v1    (nth i verts)
          v2    (nth (rem (1+ i) n) verts)
          a     (cx:bulge-arc v1 v2 (nth 2 v1))
          total (+ total (if a
                           (* (nth 2 a) (abs (nth 4 a)))
                           (distance (list (car v1) (cadr v1)) (list (car v2) (cadr v2))))))
    (setq i (1+ i)))
  total)

;; True for a closed polyline, a circle and a full ellipse.
(defun cx:ent-closed (ed / type)
  (setq type (cx:dxf 0 ed))
  (cond
    ((= type "LWPOLYLINE") (= 1 (logand 1 (cx:dxf 70 ed))))
    ((= type "CIRCLE") T)
    ((= type "ELLIPSE") (< (abs (- (- (cx:dxf 42 ed) (cx:dxf 41 ed)) (* 2.0 pi))) 1e-6))))

;; The length of a line, arc, polyline, circle (its circumference) or ellipse; nil for other objects.
(defun cx:ent-length (ed / type pts total i s)
  (setq type (cx:dxf 0 ed))
  (cond
    ((= type "LINE") (distance (cx:dxf 10 ed) (cx:dxf 11 ed)))
    ((= type "CIRCLE") (* 2.0 pi (cx:dxf 40 ed)))
    ((= type "ARC")
     (setq s (- (cx:dxf 51 ed) (cx:dxf 50 ed)))
     (if (<= s 0.0) (setq s (+ s (* 2.0 pi))))
     (* (cx:dxf 40 ed) s))
    ((= type "LWPOLYLINE") (cx:lw-length (cx:lw-verts ed) (cx:ent-closed ed)))
    ((= type "ELLIPSE")
     (setq pts (cx:ent-points ed) total 0.0 i 0)
     (repeat (1- (length pts))
       (setq total (+ total (distance (nth i pts) (nth (1+ i) pts))) i (1+ i)))
     total)))

;; Close the undo step and put the system variables back.
(defun cx:end ()
  (foreach v cx:sv (setvar (car v) (cdr v)))
  (command "_.UNDO" "_End")
  (setq cx:sv nil)
  (princ))

;; Error handler: restores everything, stays quiet on Esc.
(defun cx:err (msg)
  (if (> (getvar "CMDACTIVE") 0) (command))
  (cx:end)
  (if (and msg (not (wcmatch (strcase msg) "*BREAK*,*CANCEL*,*EXIT*")))
    (princ (strcat "\nError: " msg)))
  (princ))

;; Real X as text with at most PREC decimals and no trailing zeros ("2.50" -> "2.5", "3.00" -> "3").
(defun cx:num (x prec / s)
  (setq s (rtos x 2 prec))
  (if (wcmatch s "*.*")
    (progn
      (while (= (substr s (strlen s)) "0") (setq s (substr s 1 (1- (strlen s)))))
      (if (= (substr s (strlen s)) ".") (setq s (substr s 1 (1- (strlen s)))))))
  (if (or (= s "-0") (= s "")) "0" s))

(defun cx:ask-real (msg def / v)
  (setq v (getreal (strcat "\n" msg " <" (cx:num def 6) ">: ")))
  (if v v def))

;; Selection set to a list of entity names.
(defun cx:ss->list (ss / i out)
  (setq i 0)
  (if ss
    (repeat (sslength ss)
      (setq out (cons (ssname ss i) out)
            i   (1+ i))))
  (reverse out))

;; Replace every OLD in STR by NEW (case sensitive).
(defun cx:replace (str old new / n out pos)
  (setq n (strlen old) out "" pos 1)
  (if (= n 0)
    str
    (progn
      (while (<= pos (1+ (- (strlen str) n)))
        (if (= (substr str pos n) old)
          (setq out (strcat out new) pos (+ pos n))
          (setq out (strcat out (substr str pos 1)) pos (1+ pos))))
      (strcat out (substr str pos)))))

;; Ask for one of the keywords in BITS ("Yes No"), default DEF; returns the keyword.
(defun cx:ask-kw (msg bits def / v)
  (initget 0 bits)
  (setq v (getkword (strcat "\n" msg " [" (cx:replace bits " " "/") "] <" def ">: ")))
  (if v v def))

;; Save the system variables in VARS ((name . value) ...), set them, and open one undo step.
;; The caller declares cx:sv as a local so the saved values live exactly as long as the command.
(defun cx:start (vars)
  (setq cx:sv (mapcar (function (lambda (v) (cons (car v) (getvar (car v))))) vars))
  (command "_.UNDO" "_Begin")
  (foreach v vars (setvar (car v) (cdr v)))
  (princ))

;; A selection set holding the entity names in LST.
(defun cx:list->ss (lst / ss)
  (setq ss (ssadd))
  (foreach e lst (ssadd e ss))
  ss)

(princ "\nCXZEROLEN loaded. Type CXZEROLEN to start.")
(princ)

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