;LASF.LSP V3.0 by Bill DeShawn 9-14-2000
;USER AGREES THAT THIS PROGRAM WAS OBTAINED
;AT HIS OR HER RISK AND AGREES THAT
;BILL DESHAWN IS NOT RESPONSIBLE FOR ANY NEGATIVE OUTCOME
;AS A RESULT OF USING THIS PROGRAM
(defun lasferr (msg)
   (setvar "snapmode" sn)
   (setvar "regenmode" rg)
   (setq *error* olderr)
   (princ msg)
   (prompt ".  Please try again.")
   (setq sn nil rg nil n nil a2 nil b2 nil L1 nil L2 nil)
   (command "_.undo" "_end")
   (princ)
)
(defun c:unlasf (/ rgm mbr)
   (setq rgm (getvar "regenmode"))
   (setvar "regenmode" 0)
   (foreach mbr thawon (command "_layer" "t" mbr ""))
   (foreach mbr froze (command "_layer" "f" mbr ""))
   (command "_.regen")
   (setvar "regenmode" rgm)
   (princ)
)
(defun lasfchk (/ priorthawon priorfroze)
   (setq priorthawon nil)
   (setq priorfroze nil)
   (setq thawon nil)
   (setq froze nil)
   (setq lchk (tblnext "LAYER" T))
   (setq idx 0)
   (while lchk
      (if (= (cdr (assoc 70 lchk))0); if the layer checked is thawed and on...
         (if (= idx 0) (setq thawon (list (cdr(assoc 2 lchk)))); then start a thawed-layer list and put the name of the layer checked in it.
            (setq thawon (append priorthawon (list (cdr(assoc 2 lchk)))));or else append to the prior thawed-layer list the name of the layer checked.
         ) 
      )
      (setq lchk (tblnext "LAYER"))
      (setq priorthawon thawon);  thawon is one of two  objectives symbol of this subroutine.  It is the total amount of "thawed" and "on" layers.
      (setq idx (1+ idx))
   )
   (setq idx 0)
   (while lchk
      (if (= (cdr (assoc 70 lchk))1); if the layer checked is frozen and on...
         (if (= idx 0) (setq froze (list (cdr(assoc 2 lchk)))); then start a frozen-layer list and put the name of the layer checked in it.
            (setq froze (append priorfroze (list (cdr(assoc 2 lchk)))));or else append to the prior thawed-layer list the name of the layer checked.
         ) 
      )
      (setq lchk (tblnext "LAYER"))
      (setq priorfroze froze);  froze is the 2nd of two  objectives symbol of this subroutine.  It is the total amount of "frozen" layers.
      (setq idx (1+ idx))
   )
   (princ)
)
(defun c:lasf (/ sn rg n a2 b2 L1 L2)
   (command "_.undo" "_g")
   (setq olderr *error* *error* lasferr)
   (lasfchk)
   (setq sn (getvar "snapmode"))
   (setvar "snapmode" 0)
   (setq rg (getvar "regenmode"))
   (setvar "regenmode" 0)
   (graphscr)
   (prompt
      "Select entities on layers you want visible. :   "
   )
   (terpri)
   (setq sset (ssget))
   (command "_layer" "t" "0" "s" "0" "f" "*" "")
   (setq n (sslength sset))
   (setq index 0)
   (setq lasflst nil)
   (setq priorlst nil)
   (repeat n
      (setq a2 (ssname sset index))
      (setq b2 (entget a2))
      (setq L2 (cdr (assoc 8 b2)))
      (command "layer" "t" L2 "")
      (setq index (1+ index))
      (if (null lasflst)
         (setq lasflst (list L2))
         (setq lasflst  (append priorlst (list L2)))
      )
      (setq priorlst lasflst)
   )
   (command "_.layer" "s" (cdr (assoc 8 (entget (ssname sset 0)))) "")
   (command "_.layer" "f" "0" "")
   (prompt (strcat "\n"(itoa n) " objects picked.  \nLayer named " (getvar "clayer") " is current.  "))
   (terpri)
   (setvar "regenmode" rg)
   (command "regen")
   (setvar "snapmode" sn)
   (setq *error* olderr)
   (command "_.undo" "_end")
   (PRINC)
)
(Prompt "\n LASF.LSP - Loaded.")(princ)