Rubber band effect with more than 2 points

[Small Fish]

Hello

How would I create the rubber band effect with more than 2 points?

I my case I have 4 points. The user picks 4 points but I would also like to draw a temporary line

between points to show where the user is picking.

thanks

[BIGAL]

I think you have answered your own question only diff is that I would draw a pline then erase last

 

something like (not actual code)

(setq pt1 (getpoint))

(command "Pline" pt1)

(while (getpoint))

(command "erase" "L")

[Small Fish]

thanks BigAl

I did try something like that but it does not really work.

I want to pick four points eg Pt1 Pt2 Pt3 Pt4 collect the values and draw lines between them.

Your code will pick points then after enter it will draw a pline.

[pBe]

sample:

 
(setq pt1 (getpoint "\nPick first point:")
       pt2 (getpoint pt1 "\nPick Next point:"))

 

or

 

 
(defun c:test ()
 (setq pt1 (getpoint "\nPick first point:") pt_lst nil)
(while 
 (setq pt2 (getpoint pt1 "\nPick Next point:"))
    (if pt2 (progn
(grdraw pt1 pt2 6 1)
      (setq pt_lst (cons pt2 pt_lst)
      pt1 pt2)))
  )
 )

 

Then draw the pline

 

Hope this helps

[Small Fish]

thanks PBe - that's almost what I wanted- however Pt_lst does not seem to generate a points lists. I wanted to pick 4 points of a rectangle - bottom left (Pt1) bottom right (Pt2) top right (Pt3) top left (Pt4)

So my strings would be:

                                     (setq pt1 (getpoint "\nPick bottom left corner:")
                                     (setq pt2 (getpoint "\nPick bottom right corner:")
                                     (setq pt3 (getpoint "\nPick top right corner:")
                                     (setq pt4 (getpoint "\nPick top left corner:")

[pBe]

really?

 

did you try recalling pt_lst varaible?

!pt_lst in commnad prompt

 

or

 

 
(defun c:test ()
 (setq pt1 (getpoint "\nPick first point:") pt_lst nil)
(while 
 (setq pt2 (getpoint pt1 "\nPick Next point:"))
    (if pt2 (progn
(grdraw pt1 pt2 6 1)
      (setq pt_lst (cons pt2 pt_lst)
      pt1 pt2)))
  )
(foreach x pt_lst
  (print x)(princ)
 )
 )

as you can see the pt_lst variable is not nil

 

and I would suggest you use getcorner if its always a rectangle no need for grdraw then.

 

try it

[irneb]

Like this?

(defun grlist (lst / )
 (if (> (length lst) 1)
   (progn
     (grdraw (car lst) (cadr lst) -1 0)
     (grlist (cdr lst))
   )
 )
)

(defun getpoints (msg / pt lst)
 (if (setq pt (getpoint msg))
   (while (and (setq lst (cons pt lst))
               (setq pt (getpoint pt msg))
     )
     (redraw)
     (grlist (cons pt lst))
   )
 )
 (redraw)
 (reverse lst)
)

The getpoints method returns a list of points. The msg is the text displayed through the normal getpoint.

[pBe]

I'm so retarded... i did not include the first point ( pt1 ) on the list...

 

Apologies SmallFish.. it does create a list but missing the first point

 

 
(defun c:test ()
(setq pt1 (getpoint "\nPick first point:") pt_lst nil)
  (if pt1 (setq pt_lst (cons pt1 pt_lst))
  )
(while 
 (setq pt2 (getpoint pt1 "\nPick Next point:"))
    (if pt2 (progn
(grdraw pt1 pt2 6 1)
      (setq pt_lst (cons pt2 pt_lst)
      pt1 pt2)))
  )
(foreach x (reverse pt_lst)
  (print x)(princ)
 )
 )

 

 

or Try Irnebs' code, he's got it all covered

Word of cautiion.. if you're planning to use vla-AddLightWeightPolyline remember to convert it to a variant (array of doubles)

this list wont work with that

[Small Fish]

Hey thanks pbe and Irnb. Now I have it working more less working how I want it, after a bit of adjustment.

[pBe]

Hey thanks pbe and Irnb. Now I have it working more less working how I want it, after a bit of adjustment.

 

Your welcome, we're happy to help