判断点是否在多边形区域内的AutoLISP程序

本代码根据网上某网友代码稍作修改，版权归原作者所有^_^！

(defun pt_inorout (regionObj pt / pt_list e1 pt n i j va va_count)
  (setq	pt_list	(mapcar	'cdr
			(vl-remove-if
			  '(lambda (x) (/= 10 (car x)))
			  (entget (car regionObj))
			)
		)
  )

  (setq	i	 0
	va_count 0
	n	 (length pt_list)
	pt_list	 (append pt_list (list (car pt_list)))
  )
  (repeat n
    (setq va (-	(angle pt (nth i pt_list))
		(angle pt (nth (1+ i) pt_list))
	     )
    )
    (cond ((> va pi) (setq va (- va pi)))
	  ((< va (* -1 pi)) (setq va (+ va pi)))
    )
    (setq va_count (+ va_count va)
	  i	   (1+ i)
    )
  )
  (if (< (abs (- (abs va_count) pi)) 0.000001)
    't
    'nil
  )
)



(defun c:tt ()
  (setq	lst (entsel)
	pt  (getpoint)
  )
  (pt_inorout lst pt)
)