;;对 Pline 线检测自交叉， T 交叉，nil ok
(defun checkpl (e / tf n obj nn tf0)
  ;;(if (setq e (car (entsel)))
  ;;(progn
  (setq	tf  (vlax-curve-isclosed e)
	n   (cdr (assoc 90 (entget e)))
	obj (vlax-ename->vla-object e)
  )
  (setq	nn (/ (1+ (vlax-safearray-get-u-bound
		    (variant-value (vla-intersectwith obj obj 0))
		    1
		  )
	      )
	      3
	   )
  )
  (if tf
    (setq tf0 (= n nn))
    (setq tf0 (= (- n 2) nn))
  )
  ;; )
  ;;)
  ;;(if (not tf0)
  ;;  (princ "\n自交叉!")
  ;;  (princ "\nOk!")
  ;;)
  ;;(princ)
  (not tf0)
)