; CKEXT.LSP   [Article Figure 4]   (c)1990, Barry Bowen

; ------------------------ CKEXT ---------------------------
; VARIABLES:
; C      = Line start point
; D      = Line End point
; E      = Intersection of the four points
; ELIST  = Line entity database
; ----------------------------------------------------------
(defun CKEXT (X1 X2 X3 / C D E)
 (setq ELIST (entget (entlast))
           C (E4 10 ELIST)
           D (E4 11 ELIST))
           E (inters C D X1 X2 X3))
  (if (/= E nil)
    (progn
      (command "erase" (entlast) ""
               "line" C E "")
  ) )                  ;End If & Progn
)

; ----------------------- JSEC -----------------------------
; VARIABLES:
; DIST = Joist depth minus the chord thickness
; PT1  = Top of joist location
; PT2  = Bottom chord location
; PT3  = Insertion point for Web block
; SL1  = Selection-set for creating joist block
; ----------------------------------------------------------
(defun JSEC (/ DIST PT1 PT2 PT3)
  (setq PT1 (getpoint "\nTop of Joist: ")
        PT2 (polar PT1 (D270) DEPTH))
  (if (/= (tblsearch "block" BNAME) nil)
    (command "insert" BNAME PT1 1 1 0)
    (progn
      (command "insert" "joistsec" PT1 "" "" "")
      (setq SL1 (ssadd (entlast)))
      (command "insert" "" PT2 "1" "-1" "")
      (SSET)           ;Add to the selection-set
      (setq PT3 (polar (polar PT1 0 0.125) (D270) 1.25)
           DIST (- DEPTH 2.5))
      (command "insert" "WEB" PT3 "1" DIST "")
      (SSET)           ;Add to the selection-set
      (BLOCKIT)        ;Make it a block
  ) )                  ;End If & Progn
)