3D lisp for twisted wire pairs

You're looking for a double helix lisp. Good luck with that. A simpler way would be to create 1 twisted wire using a spiral pline and a circle, extruding it along the spiral's path and mirror it around a point satisfying the condition of creating a double helix. Here's a lisp that creates 3D sprials very easily.

Happy DNA making.

;;; A.Dudek ;;; 3DSPIRAL.LSP ;;; Copyright (C) 1993 by Autodesk, Inc. ;;; ;;; Permission to use, copy, modify, and distribute this software ;;; for any purpose and without fee is hereby granted, provided ;;; that the above copyright notice appears in all copies and that ;;; both that copyright notice and this permission notice appear in ;;; all supporting documentation. ;;; ;;; THIS SOFTWARE IS PROVIDED "AS IS" WITHOUT EXPRESS OR IMPLIED ;;; WARRANTY. ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR ;;; PURPOSE AND OF MERCHANTABILITY ARE HEREBY DISCLAIMED. ;;; ;;; DESCRIPTION ;;; ;;; This is a programming example. ;;; ;;; Designed and implemented by Kelvin R. Throop in January 1985 ;;; ;;; This program constructs a spiral. It can be loaded and called ;;; by typing either "spiral", "3dspiral" or the following: ;;; (cspiral ;;; ;;; ). ;;; ;;; ;;; Revision 3/9/95 Anthony Dudek ;;; Fixed problem of not drawing a full 360 degree helix when using only one ;;; rotation of 3dpolyline ;;;

(defun myerror (s) ; If an error (such as CTRL-C) occurs while this command is active... (if (/= s "Function cancelled") (princ (strcat "\nError: " s)) ) (setvar "cmdecho" ocmd) ; Restore saved modes (setvar "blipmode" oblp) (setq *error* olderr) ; Restore old *error* handler (princ) )

(defun cspiral (ntimes bpoint hfac lppass strad vfac / ang dist tp ainc dhinc dvinc circle dv )

(setvar "blipmode" 0) ; turn blipmode off (setvar "cmdecho" 0) ; turn cmdecho off (setq circle (* 3.141596235 2)) (setq ainc (/ circle lppass)) (setq dhinc (/ hfac lppass)) (if vfac (setq dvinc (/ vfac lppass)) ) (setq ang 0.0) (if vfac (setq dist strad dv 0.0 ) (setq dist 0.0) ) (if vfac (command "_3dpoly") ; start spiral ... (command "_pline" bpoint) ; start spiral from base point and... ) (repeat ntimes ;;; ;;; section of revised code

(if (= ntimes 1) ; if the number of ; rotations is 1 (repeat (1+ lppass) ; then calculate points ; one extra time to allow ; for the missing polyline segment at the end of ; the rotation (setq tp (polar bpoint (setq ang (+ ang ainc)) (setq dist (+ dist dhinc)) ) ) (if vfac (setq tp (list (car tp) (cadr tp) (+ dv (caddr tp))) dv (+ dv dvinc) ) ) (command tp) ; continue to the next point... ) ; close inner repeat ;;; ; otherwise (repeat lppass (setq tp (polar bpoint (setq ang (+ ang ainc)) (setq dist (+ dist dhinc)) ) ) (if vfac (setq tp (list (car tp) (cadr tp) (+ dv (caddr tp))) dv (+ dv dvinc) ) ) (command tp) ; continue to the next point... ) ; close inner repeat ) ; close if ) ; close main repeat (command "") ; until done. (princ) ) ; close defun

;;; ;;; Interactive spiral generation ;;;

(defun C:SPIRAL (/ olderr ocmd oblp nt bp cf lp) (command ".undo" "group") (setq olderr *error* *error* myerror ) (setq ocmd (getvar "cmdecho")) (setq oblp (getvar "blipmode")) (setvar "cmdecho" 0)

(initget 1) ; bp must not be null (setq bp (getpoint "\nCenter point: ")) (initget 7) ; nt must not be zero, neg, or null (setq nt (getint "\nNumber of rotations: ")) (initget 3) ; cf must not be zero, or null (setq cf (getdist "\nGrowth per rotation: ")) (initget 6) ; lp must not be zero or neg (setq lp (getint "\nPoints per rotation : ")) (cond ((null lp) (setq lp 30))) (cspiral nt bp cf lp nil nil) (setvar "cmdecho" ocmd) (setvar "blipmode" oblp) (setq *error* olderr) ; Restore old *error* handler

(princ) (command ".undo" "end") )

;;; ;;; Interactive spiral generation ;;;

(defun C:3DSPIRAL (/ olderr ocmd oblp nt bp hg vg sr lp) (command ".undo" "group") (setq olderr *error* *error* myerror ) (setq osn (getvar "OSMODE")) (setvar "OSMODE" 0) (setq ocmd (getvar "cmdecho")) (setq oblp (getvar "blipmode")) (setvar "cmdecho" 0) (initget 1) ; bp must not be null (setq bp (getpoint "\nCenter point: ")) (initget 7) ; nt must not be zero, neg, or null (setq nt (getint "\nNumber of rotations: ")) (initget 7) ; sr must not be zero, neg, or null (setq sr (getdist bp "\nStarting radius: ")) (initget 1) ; cf must not be zero, or null (setq hg (getdist "\nHorizontal growth per rotation: ")) (initget 3) ; cf must not be zero, or null (setq vg (getdist "\nVertical growth per rotation: ")) (initget 6) ; lp must not be zero or neg (setq lp (getint "\nPoints per rotation : ")) (cond ((null lp) (setq lp 30))) (cspiral nt bp hg lp sr vg) (command "_CIRCLE" bp (* 7 sr)) (setvar "cmdecho" ocmd) (setvar "blipmode" oblp) (setq *error* olderr) ; Restore old *error* handler (princ) (command ".undo" "end") (setvar "OSMODE" osn) ) (defun C:3s () (C:3dspiral) ) ;;; (princ "\t3DSPIRAL.lsp loaded") (princ)

"tomcas" a écrit dans le message de news: IXlgh.1449$ snipped-for-privacy@newsfe08.lga...

Thanks

I had to read twice. I missed your reply the first time ! :-P My pleasure, friend.

Dr Fleau