Selecting a point for a boundary?

[bsamc2000]

Okay I'm stumped.

I would like to be able to select a point and return a boundary for the area selected. Similar to a boundary hatch. I have been looking for a way to do this in VB.Net but I can not find an example. VBA would also be okay.

Any information would be greatly appreciated.

 

Thank you,

Brian

[Lee Mac]

Hmmm... never really thought about this one, but it seems to be quite tough - unless there is a method I am missing...

 

 

The way I would approach it in LISP would be to construct a line of any length or angle at the selected point and find all the intersections of this line with all the objects in the drawing (not a slow task), then find the closest intersection to the point and find the object that lies on that intersection.

 

But I'm hoping there is an easier way!

[Magnum Z]

Can't you use the hatch function's code to figure this out? Just thinking out loud.

[Magnum Z]

Didn't even know there was a boundary specific command. Never had to use it.

[uddfl]

The only way I know is to borrow the ARX function BPOLY:

 

(vl-arx-import 'BPOLY)
(setq MyBoundary (bpoly (getpoint "\nSpecify internal point:")))

[lpseifert]

not VBA and not bulletproof

; return area of picked boundary  LPS 02-2009
(defun c:da (/ elname ip sqft sqyd acre)
 (setvar "cmdecho" 0)
 (setq elname (entlast)
   ip (getpoint "Pick internal point: ")
   )
 (command "boundary" ip "")

   (if (eq (entlast) elname)
   (alert "No boundary created!")
     (progn
   (setq ar (command "area" "o" "l"))

   (setq sqft (getvar "area")
     sqyd (/ sqft 9.0)
     acre (/ sqft 43560.0)
     )
  (alert
     (strcat "\n      Square Feet = " (rtos sqft 2 2)
             "\n      Square Yards = " (rtos sqyd 2 2)
             "\n      Acres = " (rtos acre 2 3)
             "\n"
     )
  )
   (entdel (entlast))
 )
     )
     (setvar "cmdecho" 1)
     (princ)
 )

[wizman]

http://mathworld.wolfram.com/ConvexHull.html

[wizman]

or this, since you're concern are on points, group of points will always form a boundary

 

http://mathworld.wolfram.com/TravelingSalesmanProblem.html

[Lee Mac]

Nice one Wizman, right up my street if you know what I mean ...

 

But I think the OP wanted to select a point inside an object and for the LISP or VBA to recognise the object that you have clicked inside.

[wizman]

lee, you're right, most of the time i'm thinking way off the mark and this is one of them, off to bed....'-)

-\m/izan

[Lee Mac]

lee, you're right, most of the time i'm thinking way off the mark and this is one of them, off to bed....'-)

-\m/izan

 

Ahh, no worries - I think I should be off to bed soon too...

 

Nice idea though - good links.