intersection point of multiple object

[maahee]

Find out the intersection point of multiple objects. Please refer to the attached DWG file

intersection.dwg

[GLAVCVS]

Hi

Lines/polylines OB0, OB1, OB2 and OB3 intersect several different lines/polylines.
What is the criterion for determining which ones are important?
Or... Are they all important?

Edited May 7, 2025 by GLAVCVS

[maahee]

Hi GLAVCVS,

All intersection points are required, but suggest some tricks  

 

 

[GLAVCVS]

(alert "MAAHEE: Insufficient arguments:
Please try again....") 

 

Edited May 7, 2025 by GLAVCVS

[SLW210]

Automatic selection of what you show in your example drawing is not possible best I can tell, because seems to me, no common theme in what intersections you want.

 

Somewhat easy if selecting the lines/polylines or adding some sort of criteria to thin the herd.

 

Next problem, what exactly do you want to do with the intersection information? 

[BIGAL]

This will find points along a line. But note finds points also at start and end of line as they touch another object. There are ways to remove the end points. If dwgs are say horizontally inclined then could sort on X so dont use 1st and last.

 

(defun c:wow ( / )
(setq obj (vlax-ename->vla-object (car (entsel "\nPick line "))))
(setq hand (vlax-get obj 'handle))
(setq pts (list (vlax-curve-getstartPoint obj)
(vlax-curve-getendPoint obj))
)
(setq ss (ssget "F" pts (list (cons 0 "*line"))))
(setq ptsint '())
(repeat (setq x (sslength ss))
 (setq obj2 (vlax-ename->vla-object (ssname ss (setq x (1- x)))))
 (if (= (vlax-get obj2 'handle) hand)
  (princ "skip")
  (progn
  (setq intpts (vlax-invoke obj 'intersectwith obj2 acextendnone))
  (command "point" intpts)
  (setq ptsint (cons intpts ptsint))
  )
 )
)
(setq ptsint (reverse ptints))
(princ ptsint)
(princ)
)
(c:wow)

 

Like others need what is end goal.

[maahee]

Bigal sir,

Nicely, work code, smarter way to find the intersection point, thanks................................

(setq ss (ssget "F" pts (list (cons 0 "*line") (cons 0 "lwp*"))))

But it cannot find the polyline intersection point.

Edited May 8, 2025 by maahee

[BIGAL]

Ok I think I understand will redo picking multi lines then look for intersections the reverse to the way I did it.

 

Note the 3rd intersection will be found as it crosses the rectang twice.

[maahee]

14 hours ago, BIGAL said:

Ok I think I understand will redo picking multi lines then look for intersections the reverse to the way I did it.

 

Note the 3rd intersection will be found as it crosses the rectang twice.

thank, 

Edited May 9, 2025 by maahee