draw a polygon over closed polylines

Question

i try to describe this problem well with my humble English skills :
i have closed blocks on my dwg file, these blocks are consist of many Polylines which are joined together but they are not uni-body (integrated), all i want is a lisp to draw a polygon over this block and create a uni-body block. is there any way around ? thnx

Answer 1

Assuming that:

• when you say "joined" you mean their ends are touching,
• when you say "uni-body" you actually mean "joined" in the AutoCAD sense,

then try the following:

(defun convert_block_to_polyline (block / old_entlast new_entlast curr polylines_set)
  (setq old_entlast (entlast))
  (command "explode" block)
  (setq new_entlast (entlast))
  (setq
    curr (entnext old_entlast)
    polylines_set (ssadd)
    )
  (while (entnext curr)
    (ssadd curr polylines_set)
    (setq curr (entnext curr))
    )
  (command "join" (entlast) polylines_set "")
  (princ)
)

This function assumes:

• You don't want to retain the original block, if you do then its a simple question of creating a copy before you explode it, and pasting it in the same place afterwards.
• The block is made solely of objects which can be included in the join command (lines, polylines etc..)