--- ray/src/common/clip.c	1991/11/12 17:00:44	2.1
+++ ray/src/common/clip.c	2003/02/22 02:07:21	2.3
@@ -1,24 +1,80 @@
-/* Copyright (c) 1986 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char	RCSid[] = "$Id: clip.c,v 2.3 2003/02/22 02:07:21 greg Exp $";
 #endif
-
 /*
  *  clip.c - routine to clip 3D line segments to a box.
+ */
+
+/* ====================================================================
+ * The Radiance Software License, Version 1.0
  *
- *     8/28/85
+ * Copyright (c) 1990 - 2002 The Regents of the University of California,
+ * through Lawrence Berkeley National Laboratory.   All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *         notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *
+ * 3. The end-user documentation included with the redistribution,
+ *           if any, must include the following acknowledgment:
+ *             "This product includes Radiance software
+ *                 (http://radsite.lbl.gov/)
+ *                 developed by the Lawrence Berkeley National Laboratory
+ *               (http://www.lbl.gov/)."
+ *       Alternately, this acknowledgment may appear in the software itself,
+ *       if and wherever such third-party acknowledgments normally appear.
+ *
+ * 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
+ *       and "The Regents of the University of California" must
+ *       not be used to endorse or promote products derived from this
+ *       software without prior written permission. For written
+ *       permission, please contact radiance@radsite.lbl.gov.
+ *
+ * 5. Products derived from this software may not be called "Radiance",
+ *       nor may "Radiance" appear in their name, without prior written
+ *       permission of Lawrence Berkeley National Laboratory.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.   IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of Lawrence Berkeley National Laboratory.   For more
+ * information on Lawrence Berkeley National Laboratory, please see
+ * <http://www.lbl.gov/>.
  */
 
 #include  "fvect.h"
 
 #include  "plocate.h"
 
+#define MAXITER		6	/* maximum possible number of iterations */
 
+
+int
 clip(ep1, ep2, min, max)	/* clip a line segment to a box */
 FLOAT  *ep1, *ep2;
 FVECT  min, max;
 {
+	int  itlim = MAXITER;
 	int  loc1, loc2;
 	int  accept;
 	FLOAT  *dp;
@@ -41,6 +97,9 @@ FVECT  min, max;
 	
 	while (!((accept = !(loc1 | loc2)) || (loc1 & loc2))) {
 	
+		if (itlim-- <= 0)	/* past theoretical limit? */
+			return(0);	/* quit fooling around */
+
 		if (!loc1) {		/* make sure first point is outside */
 			dp = ep1; ep1 = ep2; ep2 = dp;
 			i = loc1; loc1 = loc2; loc2 = i;