;Dynamic Zoom/Pan trick.  Best for simpler drawings.
;
;	Modified from a tip in Cadylst or Cadence (don't remember which).
;	Modification requires UINT.LSP and UKWORD.LSP (see UUTILS.LSP)
;
;
(defun c:dp ( / panpt input pt1 pt2 pt3 pt4 zin zout)
(setq os_mod (getvar"osmode"))
(setvar "osmode" 0)
(setq whip (ukword 1 "In Out Stay" "\nPan and Zoom-In/Out/Stay" (if whip whip "Stay")))
(if
  (or
    (eq whip "In")
    (eq whip "Out")
  )
    (setq zspd (uint 0 "" "\nZoom Speed (Slow=1, Fast=9)" (if zspd zspd 1))
          zin (strcat(rtos(+ 1.0(/ zspd 100.000)))"x")
          zout (strcat(rtos(- 1.0(/ zspd 100.000)))"x"))
)
(setq fctr (ukword 1 "Center Pan" "Zoom by Center or Pan?" (if fctr fctr "Pan")))
(if (eq fctr "Pan")
  (setq fctr nil)
)
  (while
    (and
      (setq INPUT (grread T))
        (= (car INPUT) 5)
    )
    (if fctr
      (setq PANPT (getvar "viewctr"))
      (if PANPT
        (setq PANPT
                (polar
                  PANPT
                  (angle PANPT (cadr INPUT))
                  (/
                    (getvar"viewsize")
;                    (distance (getvar"VSMAX")(getvar"VSMIN"))
                    (/
;                      500
                      (*(getvar"viewsize")5)
                      (max(distance (cadr INPUT) PANPT)0.003)
                    )
                  )
                )
        )
        (setq PANPT (cadr INPUT))
      );if
    );
    (if (>(distance PANPT(cadr INPUT))(*(getvar"viewsize")0.003))
      (command ".zoom" "c" PANPT "")
    )
    (cond
      ((eq whip "In")
        (command ".zoom" zin))
;        (princ(strcat"\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010Pan/Zoom-In " (rtos(car PANPT))","(rtos(cadr PANPT))))
      ((eq whip "Out")
        (command ".zoom" zout))
;        (princ(strcat"\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010Pan/Zoom-Out " (rtos(car PANPT))","(rtos(cadr PANPT))))
;      ((eq whip "Stay")
;        (princ(strcat"\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010\010Panning..."
;        (rtos(car PANPT))","(rtos(cadr PANPT)))))
    )
  )
  (setvar "osmode" os_mod)
  (PRINC)
;  (C:GPDGN)
)