--- ray/src/rt/dielectric.c	1989/06/07 08:38:31	1.2
+++ ray/src/rt/dielectric.c	1996/04/17 14:01:52	2.11
@@ -16,6 +16,8 @@ static char SCCSid[] = "$SunId$ LBL";
 
 #ifdef  DISPERSE
 #include  "source.h"
+static  disperse();
+static int  lambda();
 #endif
 
 /*
@@ -48,14 +50,29 @@ static char SCCSid[] = "$SunId$ LBL";
 
 #define  MINCOS		0.997		/* minimum dot product for dispersion */
 
+extern COLOR  cextinction;		/* global coefficient of extinction */
+extern COLOR  salbedo;			/* global scattering albedo */
 
-m_dielectric(m, r)	/* color a ray which hit something transparent */
+
+static double
+mylog(x)		/* special log for extinction coefficients */
+double  x;
+{
+	if (x < 1e-40)
+		return(-100.);
+	if (x >= 1.)
+		return(0.);
+	return(log(x));
+}
+
+
+m_dielectric(m, r)	/* color a ray which hit a dielectric interface */
 OBJREC  *m;
 register RAY  *r;
 {
-	double  sqrt(), pow();
 	double  cos1, cos2, nratio;
-	COLOR  mcolor;
+	COLOR  ctrans;
+	COLOR  talb;
 	double  mabsorp;
 	double  refl, trans;
 	FVECT  dnorm;
@@ -80,19 +97,38 @@ register RAY  *r;
 		dnorm[0] = -dnorm[0];
 		dnorm[1] = -dnorm[1];
 		dnorm[2] = -dnorm[2];
-		setcolor(mcolor, pow(m->oargs.farg[0], r->rot),
-				 pow(m->oargs.farg[1], r->rot),
-				 pow(m->oargs.farg[2], r->rot));
+		setcolor(r->cext, -mylog(m->oargs.farg[0]*colval(r->pcol,RED)),
+				 -mylog(m->oargs.farg[1]*colval(r->pcol,GRN)),
+				 -mylog(m->oargs.farg[2]*colval(r->pcol,BLU)));
+		setcolor(r->albedo, 0., 0., 0.);
+		r->gecc = 0.;
+		if (m->otype == MAT_INTERFACE) {
+			setcolor(ctrans,
+				-mylog(m->oargs.farg[4]*colval(r->pcol,RED)),
+				-mylog(m->oargs.farg[5]*colval(r->pcol,GRN)),
+				-mylog(m->oargs.farg[6]*colval(r->pcol,BLU)));
+			setcolor(talb, 0., 0., 0.);
+		} else {
+			copycolor(ctrans, cextinction);
+			copycolor(talb, salbedo);
+		}
 	} else {				/* outside */
 		nratio = 1.0 / nratio;
-		if (m->otype == MAT_INTERFACE)
-			setcolor(mcolor, pow(m->oargs.farg[4], r->rot),
-					 pow(m->oargs.farg[5], r->rot),
-					 pow(m->oargs.farg[6], r->rot));
-		else
-			setcolor(mcolor, 1.0, 1.0, 1.0);
+
+		setcolor(ctrans, -mylog(m->oargs.farg[0]*colval(r->pcol,RED)),
+				 -mylog(m->oargs.farg[1]*colval(r->pcol,GRN)),
+				 -mylog(m->oargs.farg[2]*colval(r->pcol,BLU)));
+		setcolor(talb, 0., 0., 0.);
+		if (m->otype == MAT_INTERFACE) {
+			setcolor(r->cext,
+				-mylog(m->oargs.farg[4]*colval(r->pcol,RED)),
+				-mylog(m->oargs.farg[5]*colval(r->pcol,GRN)),
+				-mylog(m->oargs.farg[6]*colval(r->pcol,BLU)));
+			setcolor(r->albedo, 0., 0., 0.);
+			r->gecc = 0.;
+		}
 	}
-	mabsorp = bright(mcolor);
+	mabsorp = exp(-bright(r->cext)*r->rot);		/* approximate */
 
 	d2 = 1.0 - nratio*nratio*(1.0 - cos1*cos1);	/* compute cos theta2 */
 
@@ -113,7 +149,7 @@ register RAY  *r;
 		d1 = (d1 - d2) / (d1 + d2);
 		refl += d1 * d1;
 
-		refl /= 2.0;
+		refl *= 0.5;
 		trans = 1.0 - refl;
 
 		if (rayorigin(&p, r, REFRACTED, mabsorp*trans) == 0) {
@@ -127,14 +163,18 @@ register RAY  *r;
 			if (m->otype != MAT_DIELECTRIC
 					|| r->rod > 0.0
 					|| r->crtype & SHADOW
+					|| !directvis
 					|| m->oargs.farg[4] == 0.0
 					|| !disperse(m, r, p.rdir, trans))
 #endif
 			{
+				copycolor(p.cext, ctrans);
+				copycolor(p.albedo, talb);
 				rayvalue(&p);
-				multcolor(mcolor, r->pcol);	/* modify */
 				scalecolor(p.rcol, trans);
 				addcolor(r->rcol, p.rcol);
+				if (nratio >= 1.0-FTINY && nratio <= 1.0+FTINY)
+					r->rt = r->rot + p.rt;
 			}
 		}
 	}
@@ -151,8 +191,8 @@ register RAY  *r;
 		scalecolor(p.rcol, refl);	/* color contribution */
 		addcolor(r->rcol, p.rcol);
 	}
-
-	multcolor(r->rcol, mcolor);		/* multiply by transmittance */
+				/* rayvalue() computes absorption */
+	return(1);
 }
 
 
@@ -165,13 +205,12 @@ RAY  *r;
 FVECT  vt;
 double  tr;
 {
-	double  sqrt();
 	RAY  sray, *entray;
 	FVECT  v1, v2, n1, n2;
 	FVECT  dv, v2Xdv;
 	double  v2Xdvv2Xdv;
-	int  sn, success = 0;
-	double  omega;
+	int  success = 0;
+	SRCINDEX  si;
 	FVECT  vtmp1, vtmp2;
 	double  dtmp1, dtmp2;
 	int  l1, l2;
@@ -233,12 +272,11 @@ double  tr;
 	v2Xdvv2Xdv = DOT(v2Xdv, v2Xdv);
 
 					/* check sources */
-	for (sn = 0; sn < nsources; sn++) {
+	initsrcindex(&si);
+	while (srcray(&sray, r, &si)) {
 
-		if ((omega = srcray(&sray, r, sn)) == 0.0 ||
-				DOT(sray.rdir, v2) < MINCOS)
+		if (DOT(sray.rdir, v2) < MINCOS)
 			continue;			/* bad source */
-		
 						/* adjust source ray */
 
 		dtmp1 = DOT(v2Xdv, sray.rdir) / v2Xdvv2Xdv;
@@ -263,7 +301,7 @@ double  tr;
 		 */
 		 
 		fcross(vtmp1, v2Xdv, sray.rdir);
-		dtmp1 = sqrt(omega  / v2Xdvv2Xdv / PI);
+		dtmp1 = sqrt(si.dom  / v2Xdvv2Xdv / PI);
 
 							/* compute first ray */
 		for (i = 0; i < 3; i++)