;; | ----------------------------------------------------------------------------
;; | GE_PolyInters
;; | ----------------------------------------------------------------------------
;; | Function : Checks if a given polygon intersects itself in any of its
;; |            segments
;; | Arguments: 'vlist'  - List of all points of the polygon
;; |            'Closed' - Flag (T of nil) to indicate if polygon is closed.
;; | Returns  : 'IPtLst' or 'nil' - IPtLst is a list of all coordiantes where
;; |            the intersection occurs
;; | Updated  : January 9, 2000
;; | e-mail   : rakesh.rao@4d-technologies.com 
;; | Web      : www.4d-technologies.com
;; | ----------------------------------------------------------------------------


(defun GE_PolyInters( vlist Closed / IPtLst _IPtLst IPt Seg SegLst )

(setq
	SegLst (GE_GetSegmentPoints vlist Closed)
	IPtLst '()
)
(foreach Seg SegLst
	(if (setq _IPtLst (GE_SegInters (car Seg) (cadr Seg) SegLst T))
	(progn
		(setq _IPtLst (nth 0 _IPtLst))
		(foreach IPt _IPtLst
			(if (not (member IPt IPtLst))
				(setq IPtLst (cons IPt IPtLst))
			)
		)
	))
)
IPtLst
)