cog of a set of scattered lines

Dear All

Do you have any lisp program for finding cog of a set of scattered lines?

cog to marked on drawing in circle

Nithin

OK, you can stop now. Three threads all asking the same question is really quite enough.

I'm still not sure what you are asking. Post an image or attach an actual DWG file.

i have removed other posts sry.

What are you trying to draw?

The only two definitions of "cog" that I am familiar with are the teeth on the rim of a gear or a tenon projecting from the end of a beam that fits into a mortise. If it is a math term it is one I am not familiar with.

i need to find center of gravity of these lines.

and the point to be marked as a circle

I assume COG = Center of Gravity?

Create a region from the boundary using the REGION or BOUNDARY commands, and then query the mass properties of the region using MASSPROP.

Alternatively, ask Google.

See post number 6 of this thread.

http://www.cadtutor.net/forum/showthread.php?24528-Lisp-to-find-Center-of-Gravity

then how to find center of gravity of these lines(attached)

Join them and create a region as per Lee Mac's suggestion?

If i Join them and created a region, then i will get cog of the area right?

but i need cog of these lines

There is no need to repeat a reply.

You want the "cog" for individual lines or a group of lines? If it is a group of lines then I would consider the "group" to be a single entity thus Lee Mac's suggestion should apply.

This is what I would do.

Start with the original set of lines (white) as shown on the left.

Add connecting lines (red) as shown in middle.

Execute the REGION command to create region as shown (red) on the right.

Run the MASSPROP command. Results shown in text box on far right.

As the centre of gravity of each individual line is at its centre point, I am not sure that creating a region bounded by a projected length of each line would give the correct result.

One would have to sum the moments of each line about the centre of gravity (wherever it was), so that the result was zero. It seems to me that that is not what AutoCAD is doing.

AutoCAD can deal with areas, but this case would need to be dealing with some sort of space frame. My maths is not up to it

A shot in the dark...

(defun C:CGLIN ( / ss l i e p1 p2 d pm)
 (if
   (setq ss (ssget '((0 . "LINE"))))
   (progn
     (setq l '(0.0 0.0 0.0 0.0))
     (repeat (setq i (sslength ss))
       (setq e (entget (ssname ss (setq i (1- i))))
             p1 (cdr (assoc 10 e))
             p2 (cdr (assoc 11 e))
             d  (distance p1 p2)
             pm (mapcar '(lambda (a b) (* (+ a b) 0.5 d)) p1 p2)
             )
       (setq l (mapcar '+ l (cons d pm)))
       )
     (entmake
       (list
         '(0 . "POINT")
         (cons 10 (mapcar '(lambda (a) (/ a (car l))) (cdr l)))
         )
       )
     )
   )
 (princ)
 )

Perhaps the solutions in these two threads will work.

http://www.cadtutor.net/forum/showthread.php?48143-LISP-to-find-midpoint-of-multiple-lines

http://www.cadtutor.net/forum/showthread.php?49675-.NET-Find-COG-of-linear-elements