lisp that converts intersections of polylines into vertices of a polyline.

[Zoltan]

I need a lisp that draws a polyline at the intersections of other polylines and where these intersections will be verticies. 

 

On the picture below, where the blue lines cross the red line, i want the lisp to draw a polyline where the crossing points will be vertices. 

 

Could someone help me with this? I have no clue how to do it.

 

Thanks,

Zoltan

 

https://ibb.co/443gYg5

 

 

[mhupp]

Pulled mostly from here

 

(defun c:interset (/ spm sel lst)
  (vl-load-com)
  (if (setq sel (ssget))
    (setq lst (LM:intersectionsinset sel))
    ;Sort points left to right
    (setq tlst (mapcar 'cadr
                       (vl-sort tlst
                                '(lambda (a b)
                                   (if (equal (caar a) (caar b) 1e-6)
                                     (< (car (car a)) (car (car b)))
                                   )
                                 )
                       )
               )
    )
  )
  (entmake
    (append
      (list
        (cons 0 "LWPOLYLINE")
        (cons 100 "AcDbEntity")
        (cons 100 "AcDbPolyline")
        (cons 90 (length lst))
        (cons 70 0)
      )
      (mapcar (function (lambda (p) (cons 10 p))) lst)
    )
  )
  (princ)
)
;; Intersections in Set  -  Lee Mac
;; Returns a list of all points of intersection between all objects in a supplied selection set.
;; sel - [sel] Selection Set
(defun LM:intersectionsinset (sel / id1 id2 ob1 ob2 rtn)
  (repeat (setq id1 (sslength sel))
    (setq ob1 (vlax-ename->vla-object (ssname sel (setq id1 (1- id1)))))
    (repeat (setq id2 id1)
      (setq ob2 (vlax-ename->vla-object (ssname sel (setq id2 (1- id2))))
            rtn (cons (LM:intersections ob1 ob2 acextendnone) rtn)
      )
    )
  )
  (apply 'append (reverse rtn))
)
;; Intersections  -  Lee Mac
;; Returns a list of all points of intersection between two objects
;; for the given intersection mode.
;; ob1,ob2 - [vla] VLA-Objects
;;     mod - [int] acextendoption enum of intersectwith method
(defun LM:intersections (ob1 ob2 mod / lst rtn)
  (if (and (vlax-method-applicable-p ob1 'intersectwith)
           (vlax-method-applicable-p ob2 'intersectwith)
           (setq lst (vlax-invoke ob1 'intersectwith ob2 mod))
      )
    (repeat (/ (length lst) 3)
      (setq rtn (cons (list (car lst) (cadr lst) (caddr lst)) rtn)
            lst (cdddr lst)
      )
    )
  )
  (reverse rtn)
)

 

Edited January 13, 2022 by mhupp
added prompts

[BIGAL]

Turn off Blue lines, add end lines to the 2 plines, do Bpoly, delete the 2 end lines, turn on blues lines. No complicated code needed. Could be done in a lisp. So if this is for hatch can do selecting bpoly.

[ronjonp]

You could also use CAB's break code then pedit join.

 

 

Edited January 13, 2022 by ronjonp