Is Boolean masking possible?

Hello,

My terminology may be a bit off, I'm quite new to AutoCAD.

Here's what I'd like to do:

I have an nxn rectangular array of blocks.

I'd like to "mask" that with a circle.

Any blocks that are inside the circle, I wish to retain.

Any blocks that are cut by the circle perimeter, or are outside, I wish to delete completely.

Is there an easy way to do this without resorting to programming?

Thanks for any help!

try extrim

BigAl, thanks, I'll try that later today

Any blocks that are cut by the circle perimeter, or are outside, I wish to delete completely

EXTRIM won't do this, will it? the only way i know to do this is using a lisp routine, which i am sure i have seen written by lee mac which enables you to select everything inside an ellipse (i think....)

DesignerStuart, I agree - I think it will trim the block to the edge rather than delete completely. I'll try it!

okay so i i found select within a curve, by alan j t. found at AUGI forum but was sure i saw it here a while back. it actually does the opposite of what you want, but it's a start?

(defun c:SWC (/ _pac add ss i temp i2)   ;; Select Within Curve   ;; Alan J. Thompson, 03.31.11 / 05.11.11    (vl-load-com)    (defun _pac (e / l v d lst)     (setq d (- (setq v (/ (setq l (vlax-curve-getDistAtParam e (vlax-curve-getEndParam e))) 100.))))     (while (< (setq d (+ d v)) l)       (setq lst (cons (trans (vlax-curve-getPointAtDist e d) 0 1) lst))     )   )    (princ "\nSelect closed curves to select object(s) within: ")   (if (setq add (ssadd)             ss  (ssget '((-4 . "<OR")                          (0 . "CIRCLE,ELLIPSE")                          (-4 . "<AND")                          (0 . "*POLYLINE")                          (-4 . "&=")                          (70 . 1)                          (-4 . "AND>")                          (-4 . "OR>")                         )                 )       )     (progn (repeat (setq i (sslength ss))              (if (setq temp (ssget "_WP" (_pac (ssname ss (setq i (1- i))))))                (repeat (setq i2 (sslength temp)) (ssadd (ssname temp (setq i2 (1- i2))) add))              )            )            (sssetfirst nil add)            (ssget "_I")     )   )   (princ) )

Great, I'll try to get my head around that. I've not programmed AutoCAD in many a year....!

it's easy - copy contents into a notepad file and rename it "SWC.lsp" then drag and drop into a drawing. now the command SWC should select everything wholly inside your circle.

then i guess you have to hide this stuff, and delete everything else. not beautiful, but it will work.

Great, thanks! Time to lubricate the brain.

Otherwise give these a go, quickly written but should work:

([color=BLUE]defun[/color] SelectInside ( entity acc [color=BLUE]/[/color] i j l )
 ([color=BLUE]cond[/color]
   ( ([color=BLUE]vlax-curve-isclosed[/color] entity)
     ([color=BLUE]setq[/color] i ([color=BLUE]/[/color] ([color=BLUE]vlax-curve-getdistatparam[/color] entity ([color=BLUE]vlax-curve-getendparam[/color] entity)) acc) j ([color=BLUE]-[/color] i))
     ([color=BLUE]repeat[/color] ([color=BLUE]fix[/color] acc)
       ([color=BLUE]setq[/color] l ([color=BLUE]cons[/color] ([color=BLUE]trans[/color] ([color=BLUE]vlax-curve-getpointatdist[/color] entity ([color=BLUE]setq[/color] j ([color=BLUE]+[/color] j i))) 0 1) l))
     )
     ([color=BLUE]ssget[/color] [color=MAROON]"_WP"[/color] l)
   )
 )
)

([color=BLUE]defun[/color] c:SelIn ( [color=BLUE]/[/color] s ) ([color=BLUE]princ[/color] [color=MAROON]"\nSelect Boundary Object: "[/color])
 ([color=BLUE]if[/color]
   ([color=BLUE]setq[/color] s
     ([color=BLUE]ssget[/color] [color=MAROON]"_+.:E:S"[/color]
      '(
         (-4 . [color=MAROON]"<OR"[/color])
           (0 . [color=MAROON]"CIRCLE,ELLIPSE"[/color])
           (-4 . [color=MAROON]"<AND"[/color])
             (0 . [color=MAROON]"*POLYLINE,SPLINE"[/color])
             (-4 . [color=MAROON]"&="[/color])
             (70 . 1)
           (-4 . [color=MAROON]"AND>"[/color])
         (-4 . [color=MAROON]"OR>"[/color])
       )
     )
   )
   ([color=BLUE]sssetfirst[/color] [color=BLUE]nil[/color] (SelectInside ([color=BLUE]ssname[/color] s 0) 100))
 )
 ([color=BLUE]princ[/color])
)

([color=BLUE]defun[/color] c:SelOut ( [color=BLUE]/[/color] a e i s )
 ([color=BLUE]if[/color]
   ([color=BLUE]and[/color]
     ([color=BLUE]princ[/color] [color=MAROON]"Select Exterior Set <All>: "[/color])
     ([color=BLUE]setq[/color] a
       ([color=BLUE]cond[/color]
         ( ([color=BLUE]ssget[/color]      ([color=BLUE]list[/color] ([color=BLUE]cons[/color] 410 ([color=BLUE]getvar[/color] 'CTAB)))) )
         ( ([color=BLUE]ssget[/color] [color=MAROON]"_X"[/color] ([color=BLUE]list[/color] ([color=BLUE]cons[/color] 410 ([color=BLUE]getvar[/color] 'CTAB)))) )
       )
     )
     ([color=BLUE]princ[/color] [color=MAROON]"\nSelect Boundary Object: "[/color])
     ([color=BLUE]setq[/color] s
       ([color=BLUE]ssget[/color] [color=MAROON]"_+.:E:S"[/color]
        '(
           (-4 . [color=MAROON]"<OR"[/color])
             (0 . [color=MAROON]"CIRCLE,ELLIPSE"[/color])
             (-4 . [color=MAROON]"<AND"[/color])
               (0 . [color=MAROON]"*POLYLINE,SPLINE"[/color])
               (-4 . [color=MAROON]"&="[/color])
               (70 . 1)
             (-4 . [color=MAROON]"AND>"[/color])
           (-4 . [color=MAROON]"OR>"[/color])
         )
       )
     )
   )
   ([color=BLUE]if[/color] ([color=BLUE]setq[/color] s (SelectInside ([color=BLUE]ssname[/color] s 0) 100))
     ([color=BLUE]repeat[/color] ([color=BLUE]setq[/color] i ([color=BLUE]sslength[/color] a))
       ([color=BLUE]if[/color] ([color=BLUE]ssmemb[/color] ([color=BLUE]setq[/color] e ([color=BLUE]ssname[/color] a ([color=BLUE]setq[/color] i ([color=BLUE]1-[/color] i)))) s)
         ([color=BLUE]ssdel[/color] e a)
       )
     )
   )
 )
 ([color=BLUE]sssetfirst[/color] [color=BLUE]nil[/color] a)
 ([color=BLUE]princ[/color])
)
([color=BLUE]vl-load-com[/color]) ([color=BLUE]princ[/color])

Commands: SelIn and SelOut

legend, lee, nice one.

although the SELOUT doesn't seem to work? i select the set of objects, fine, then click my circle and nothing happens. am i doing it wrong?

legend, lee, nice one.

although the SELOUT doesn't seem to work? i select the set of objects, fine, then click my circle and nothing happens. am i doing it wrong?

Cheers mate

For SelOut there are two prompts - one for the Exterior Set and one for the Boundary Object.

EDIT: I should learn to read - I'll do some testing.

it works with a rectangle, but not a circle

For the WP Selection to work the boundary object needs to be completely on screen, but other than that, it seems to work for me.

yes it is working well for me too. must have been my error.

Thanks for testing, glad it works