How it can check if there is an intersection???

[kasra]

Hi.
Is there a solution(s) to find out that there is an intersection between a line with a lwpline?????
I know that it should be checked all entities of lwpline for existance of intersection with a line. but, cause i 'm new in programming, it's difficult for me to get entities of lwpline one after another.
please guide me how i can check one by one???
Thank you for pay attention.

[Lee Mac]

Try this:

;; Finds all Intersections between obj1 & obj2
;; Args: obj1,obj2
;; VLA-Objects with Intersectwith method available
;; Returns: List of Intersections (or nil)

(defun GetIntersections (obj1 obj2 / GroupByNum)
  ;; Lee Mac  ~  16.04.10
  
  (defun GroupByNum (lst num / rtn) (setq rtn nil)
  
    (if lst
      (cons (reverse
              (repeat num
                (progn
                  (setq rtn (cons (car lst) rtn)
                        lst (cdr lst))
                  rtn)))

            (GroupByNum lst num))))

  (GroupByNum (vlax-invoke obj1 'IntersectWith obj2 acExtendNone) 3))

Test Function:

(defun c:test (/ e1 e2)
  (vl-load-com)

  (if (apply (function and)
             (mapcar
               (function
                 (lambda (str sym)
                   (set sym (car (entsel str)))))

               '("\nSelect First Object: " "\nSelect Second Object: ") '(e1 e2)))

    (print (apply (function GetIntersections)
                  (mapcar (function vlax-ename->vla-object) (list e1 e2)))))

  (princ))

[Lee Mac]

Another, for a Selection Set:

(defun Get_Inters (ss / GroupByNum i j obj1 obj2 iLst)
  ;; Lee Mac  ~  19.01.10

  (defun GroupByNum (lst num / rtn) (setq rtn nil)
  
    (if lst
      (cons (reverse
              (repeat num
                (progn
                  (setq rtn (cons (car lst) rtn)
                        lst (cdr lst))
                  rtn)))

            (GroupByNum lst num))))

  (setq i (sslength ss))

  (while (not (minusp (setq j (1- i) i (1- i))))
    (setq obj1 (vlax-ename->vla-object (ssname ss i)))

    (while (not (minusp (setq j (1- j))))
      (setq obj2 (vlax-ename->vla-object (ssname ss j)))

      (setq iLst (append iLst
                   (GroupByNUm
                     (vlax-invoke obj1 'IntersectWith obj2 acExtendNone) 3)))))

  iLst)

Test Function:

(defun c:test (/ ss x)
  (vl-load-com)

  (if (setq ss (ssget))
    (foreach x (Get_Inters ss)
      (command "_.point" "_non" x)))

  (princ))

[kasra]

Hi Dear Lee Mac.
I should test your post in my routine. I'll tell the result after that.
thanks for ur helping.

[kasra]

Hi.
I have a problem with this Lisp-command
(vlax-invoke obj1 'IntersectWith obj2 acExtendNone)
to finding the intersection point between 2 objects that do not intersect with each other in drawing, but if i strech one to the other one, it can find the point.
Isn't it possibleto find the point with this command?
Thanks for helping.

[Lee Mac]

Investigate the ExtendOption parameter of the IntersectWith method:

IntersectWith Method

Gets the points where one object intersects another object in the drawing.

... ...

ExtendOption

AcExtendOption enum; input-only

This option specifies if none, one or both, of the objects are to be extended in order to attempt an intersection.

acExtendNone
Does not extend either object.

acExtendThisEntity
Extends the base object.

acExtendOtherEntity
Extends the object passed as an argument.

acExtendBoth
Extends both objects.

[MSasu]

You should replace acExtendNone with either acExtendBoth, acExtendThisEntity or acExtendOtherEntity.

[kasra]

Thank you.
I got the solution.
What references you suggest for studing about all options of all method?

[Lee Mac]

What references you suggest for studing about all options of all method?

Visual LISP IDE Help Docs:

http://lee-mac.com/functioninfo.html

[kasra]

Ok. Thanx a lot.
I will try it before any request.