--- ray/src/rt/glass.c	1993/08/24 12:59:24	2.6
+++ ray/src/rt/glass.c	2003/02/22 02:07:28	2.10
@@ -1,17 +1,71 @@
-/* Copyright (c) 1991 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char	RCSid[] = "$Id: glass.c,v 2.10 2003/02/22 02:07:28 greg Exp $";
 #endif
-
 /*
  *  glass.c - simpler shading function for thin glass surfaces.
+ */
+
+/* ====================================================================
+ * The Radiance Software License, Version 1.0
  *
- *     11/14/86
+ * 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  "ray.h"
 
+#include  "otypes.h"
+
 /*
  *  This definition of glass provides for a quick calculation
  *  using a single surface where two closely spaced parallel
@@ -24,7 +78,7 @@ static char SCCSid[] = "$SunId$ LBL";
  *	modifier glass id
  *	0
  *	0
- *	3 red grn blu
+ *	3+ red grn blu [refractive_index]
  *
  *  The color is used for the transmission at normal incidence.
  *  To compute transmissivity (tn) from transmittance (Tn) use:
@@ -51,8 +105,10 @@ register RAY  *r;
 	FVECT  pnorm;
 	double  rindex, cos2;
 	COLOR  trans, refl;
+	int  hastexture;
 	double  d, r1e, r1m;
 	double  transtest, transdist;
+	double  mirtest, mirdist;
 	RAY  p;
 	register int  i;
 						/* check arguments */
@@ -67,11 +123,16 @@ register RAY  *r;
 
 	if (r->rod < 0.0)			/* reorient if necessary */
 		flipsurface(r);
-	transtest = 0;
-	transdist = r->rot;
+	mirtest = transtest = 0;
+	mirdist = transdist = r->rot;
 						/* get modifiers */
 	raytexture(r, m->omod);
-	pdot = raynormal(pnorm, r);
+	if (hastexture = DOT(r->pert,r->pert) > FTINY*FTINY)
+		pdot = raynormal(pnorm, r);
+	else {
+		VCOPY(pnorm, r->ron);
+		pdot = r->rod;
+	}
 						/* angular transmission */
 	cos2 = sqrt( (1.0-1.0/(rindex*rindex)) +
 		     pdot*pdot/(rindex*rindex) );
@@ -92,8 +153,7 @@ register RAY  *r;
 	}
 						/* transmitted ray */
 	if (rayorigin(&p, r, TRANS, bright(trans)) == 0) {
-		if (!(r->crtype & SHADOW) &&
-				DOT(r->pert,r->pert) > FTINY*FTINY) {
+		if (!(r->crtype & SHADOW) && hastexture) {
 			for (i = 0; i < 3; i++)		/* perturb direction */
 				p.rdir[i] = r->rdir[i] +
 						2.*(1.-rindex)*r->pert[i];
@@ -113,8 +173,10 @@ register RAY  *r;
 		transdist = r->rot + p.rt;
 	}
 
-	if (r->crtype & SHADOW)			/* skip reflected ray */
-		return;
+	if (r->crtype & SHADOW) {		/* skip reflected ray */
+		r->rt = transdist;
+		return(1);
+	}
 						/* compute reflectance */
 	for (i = 0; i < 3; i++) {
 		d = colval(mcolor, i);
@@ -129,7 +191,16 @@ register RAY  *r;
 		rayvalue(&p);
 		multcolor(p.rcol, refl);
 		addcolor(r->rcol, p.rcol);
+		if (!hastexture && r->ro != NULL && isflat(r->ro->otype)) {
+			mirtest = 2.0*bright(p.rcol);
+			mirdist = r->rot + p.rt;
+		}
 	}
-	if (transtest > bright(r->rcol))
+                                        /* check distance */
+	d = bright(r->rcol);
+	if (transtest > d)
 		r->rt = transdist;
+	else if (mirtest > d)
+		r->rt = mirdist;
+	return(1);
 }