--- ray/src/rt/glass.c	1992/11/30 12:02:54	2.5
+++ ray/src/rt/glass.c	2013/08/07 05:10:09	2.20
@@ -1,16 +1,15 @@
-/* Copyright (c) 1991 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char RCSid[] = "$Id: glass.c,v 2.20 2013/08/07 05:10:09 greg Exp $";
 #endif
-
 /*
  *  glass.c - simpler shading function for thin glass surfaces.
- *
- *     11/14/86
  */
 
+#include "copyright.h"
+
 #include  "ray.h"
+#include  "otypes.h"
+#include  "rtotypes.h"
 
 /*
  *  This definition of glass provides for a quick calculation
@@ -24,7 +23,7 @@ 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:
@@ -42,17 +41,21 @@ static char SCCSid[] = "$SunId$ LBL";
 #define  RINDEX		1.52		/* refractive index of glass */
 
 
-m_glass(m, r)		/* color a ray which hit a thin glass surface */
-OBJREC  *m;
-register RAY  *r;
+extern int
+m_glass(		/* color a ray which hit a thin glass surface */
+	OBJREC  *m,
+	register RAY  *r
+)
 {
 	COLOR  mcolor;
 	double  pdot;
 	FVECT  pnorm;
-	double  rindex, cos2;
+	double  rindex=0, cos2;
 	COLOR  trans, refl;
+	int  hastexture, hastrans;
 	double  d, r1e, r1m;
 	double  transtest, transdist;
+	double  mirtest, mirdist;
 	RAY  p;
 	register int  i;
 						/* check arguments */
@@ -62,58 +65,73 @@ register RAY  *r;
 		rindex = m->oargs.farg[3];	/* use their value */
 	else
 		objerror(m, USER, "bad arguments");
-
+						/* check transmission */
 	setcolor(mcolor, m->oargs.farg[0], m->oargs.farg[1], m->oargs.farg[2]);
-
-	if (r->rod < 0.0)			/* reorient if necessary */
-		flipsurface(r);
-	transtest = 0;
+	if ((hastrans = (intens(mcolor) > 1e-15))) {
+		for (i = 0; i < 3; i++)
+			if (colval(mcolor,i) < 1e-15)
+				colval(mcolor,i) = 1e-15;
+	} else if (r->crtype & SHADOW)
+		return(1);
 						/* get modifiers */
 	raytexture(r, m->omod);
-	pdot = raynormal(pnorm, r);
+	if (r->rod < 0.0)			/* reorient if necessary */
+		flipsurface(r);
+	mirtest = transtest = 0;
+	mirdist = transdist = r->rot;
+						/* perturb normal */
+	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) );
-	setcolor(mcolor, pow(colval(mcolor,RED), 1.0/cos2),
-			 pow(colval(mcolor,GRN), 1.0/cos2),
-			 pow(colval(mcolor,BLU), 1.0/cos2));
+	if (hastrans)
+		setcolor(mcolor, pow(colval(mcolor,RED), 1.0/cos2),
+				 pow(colval(mcolor,GRN), 1.0/cos2),
+				 pow(colval(mcolor,BLU), 1.0/cos2));
 
 						/* compute reflection */
 	r1e = (pdot - rindex*cos2) / (pdot + rindex*cos2);
 	r1e *= r1e;
 	r1m = (1.0/pdot - rindex/cos2) / (1.0/pdot + rindex/cos2);
 	r1m *= r1m;
-						/* compute transmittance */
-	for (i = 0; i < 3; i++) {
-		d = colval(mcolor, i);
-		colval(trans,i) = .5*(1.0-r1e)*(1.0-r1e)*d/(1.0-r1e*r1e*d*d);
-		colval(trans,i) += .5*(1.0-r1m)*(1.0-r1m)*d/(1.0-r1m*r1m*d*d);
-	}
+						/* compute transmission */
+	if (hastrans) {
+		for (i = 0; i < 3; i++) {
+			d = colval(mcolor, i);
+			colval(trans,i) = .5*(1.0-r1e)*(1.0-r1e)*d /
+							(1.0-r1e*r1e*d*d);
+			colval(trans,i) += .5*(1.0-r1m)*(1.0-r1m)*d /
+							(1.0-r1m*r1m*d*d);
+		}
+		multcolor(trans, r->pcol);	/* modify by pattern */
 						/* transmitted ray */
-	if (rayorigin(&p, r, TRANS, bright(trans)) == 0) {
-		if (!(r->crtype & SHADOW) &&
-				DOT(r->pert,r->pert) > FTINY*FTINY) {
-			for (i = 0; i < 3; i++)		/* perturb direction */
-				p.rdir[i] = r->rdir[i] +
-						2.*(1.-rindex)*r->pert[i];
-			if (normalize(p.rdir) == 0.0) {
-				objerror(m, WARNING, "bad perturbation");
+		if (rayorigin(&p, TRANS, r, trans) == 0) {
+			if (!(r->crtype & SHADOW) && hastexture) {
+				VSUM(p.rdir, r->rdir, r->pert, 2.*(1.-rindex));
+				if (normalize(p.rdir) == 0.0) {
+					objerror(m, WARNING, "bad perturbation");
+					VCOPY(p.rdir, r->rdir);
+				}
+			} else {
 				VCOPY(p.rdir, r->rdir);
+				transtest = 2;
 			}
-		} else {
-			VCOPY(p.rdir, r->rdir);
-			transtest = 2;
+			rayvalue(&p);
+			multcolor(p.rcol, p.rcoef);
+			addcolor(r->rcol, p.rcol);
+			transtest *= bright(p.rcol);
+			transdist = r->rot + p.rt;
 		}
-		rayvalue(&p);
-		multcolor(p.rcol, r->pcol);	/* modify */
-		multcolor(p.rcol, trans);
-		addcolor(r->rcol, p.rcol);
-		transtest *= bright(p.rcol);
-		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);
@@ -122,13 +140,22 @@ register RAY  *r;
 		colval(refl,i) += .5*r1m*(1.0+(1.0-2.0*r1m)*d)/(1.0-r1m*r1m*d);
 	}
 						/* reflected ray */
-	if (rayorigin(&p, r, REFLECTED, bright(refl)) == 0) {
-		for (i = 0; i < 3; i++)
-			p.rdir[i] = r->rdir[i] + 2.0*pdot*pnorm[i];
+	if (rayorigin(&p, REFLECTED, r, refl) == 0) {
+		VSUM(p.rdir, r->rdir, pnorm, 2.*pdot);
+		checknorm(p.rdir);
 		rayvalue(&p);
-		multcolor(p.rcol, refl);
+		multcolor(p.rcol, p.rcoef);
 		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);
 }