--- ray/src/rt/normal.c	1989/06/07 08:35:14	1.3
+++ ray/src/rt/normal.c	1991/10/30 14:53:55	1.14
@@ -1,4 +1,4 @@
-/* Copyright (c) 1986 Regents of the University of California */
+/* Copyright (c) 1991 Regents of the University of California */
 
 #ifndef lint
 static char SCCSid[] = "$SunId$ LBL";
@@ -38,10 +38,10 @@ extern double  exp();
 
 typedef struct {
 	OBJREC  *mp;		/* material pointer */
-	RAY  *pr;		/* intersected ray */
 	COLOR  mcolor;		/* color of this material */
 	COLOR  scolor;		/* color of specular component */
 	FVECT  vrefl;		/* vector in direction of reflected ray */
+	FVECT  prdir;		/* vector in transmitted direction */
 	double  alpha2;		/* roughness squared times 2 */
 	double  rdiff, rspec;	/* reflected specular, diffuse */
 	double  trans;		/* transmissivity */
@@ -70,9 +70,9 @@ double  omega;			/* light source size */
 
 	if (ldot > FTINY && np->rdiff > FTINY) {
 		/*
-		 *  Compute and add diffuse component to returned color.
-		 *  The diffuse component will always be modified by the
-		 *  color of the material.
+		 *  Compute and add diffuse reflected component to returned
+		 *  color.  The diffuse reflected component will always be
+		 *  modified by the color of the material.
 		 */
 		copycolor(ctmp, np->mcolor);
 		dtmp = ldot * omega * np->rdiff / PI;
@@ -91,7 +91,7 @@ double  omega;			/* light source size */
 						/* worth using? */
 		if (dtmp > FTINY) {
 			copycolor(ctmp, np->scolor);
-			dtmp *= omega;
+			dtmp *= omega / np->pdot;
 			scalecolor(ctmp, dtmp);
 			addcolor(cval, ctmp);
 		}
@@ -107,16 +107,17 @@ double  omega;			/* light source size */
 	}
 	if (ldot < -FTINY && np->tspec > FTINY && np->alpha2 > FTINY) {
 		/*
-		 *  Compute specular transmission.
+		 *  Compute specular transmission.  Specular transmission
+		 *  is always modified by material color.
 		 */
 						/* roughness + source */
 		dtmp = np->alpha2 + omega/(2.0*PI);
 						/* gaussian */
-		dtmp = exp((DOT(np->pr->rdir,ldir)-1.)/dtmp)/(2.*PI)/dtmp;
+		dtmp = exp((DOT(np->prdir,ldir)-1.)/dtmp)/(2.*PI)/dtmp;
 						/* worth using? */
 		if (dtmp > FTINY) {
 			copycolor(ctmp, np->mcolor);
-			dtmp *= np->tspec * omega;
+			dtmp *= np->tspec * omega / np->pdot;
 			scalecolor(ctmp, dtmp);
 			addcolor(cval, ctmp);
 		}
@@ -129,8 +130,7 @@ register OBJREC  *m;
 register RAY  *r;
 {
 	NORMDAT  nd;
-	double  ldot;
-	double  omega;
+	double  transtest, transdist;
 	double  dtmp;
 	COLOR  ctmp;
 	register int  i;
@@ -141,7 +141,6 @@ register RAY  *r;
 	if (r->crtype & SHADOW && m->otype != MAT_TRANS)
 		return;
 	nd.mp = m;
-	nd.pr = r;
 						/* get material color */
 	setcolor(nd.mcolor, m->oargs.farg[0],
 			   m->oargs.farg[1],
@@ -155,7 +154,10 @@ register RAY  *r;
 						/* get modifiers */
 	raytexture(r, m->omod);
 	nd.pdot = raynormal(nd.pnorm, r);	/* perturb normal */
+	if (nd.pdot < .001)
+		nd.pdot = .001;			/* non-zero for dirnorm() */
 	multcolor(nd.mcolor, r->pcol);		/* modify material color */
+	transtest = 0;
 						/* get specular component */
 	nd.rspec = m->oargs.farg[3];
 
@@ -190,16 +192,27 @@ register RAY  *r;
 		nd.trans = m->oargs.farg[5]*(1.0 - nd.rspec);
 		nd.tspec = nd.trans * m->oargs.farg[6];
 		nd.tdiff = nd.trans - nd.tspec;
+		if (r->crtype & SHADOW || DOT(r->pert,r->pert) <= FTINY*FTINY) {
+			VCOPY(nd.prdir, r->rdir);
+			transtest = 2;
+		} else {
+			for (i = 0; i < 3; i++)		/* perturb direction */
+				nd.prdir[i] = r->rdir[i] - .75*r->pert[i];
+			normalize(nd.prdir);
+		}
 	} else
 		nd.tdiff = nd.tspec = nd.trans = 0.0;
 						/* transmitted ray */
 	if (nd.tspec > FTINY && nd.alpha2 <= FTINY) {
 		RAY  lr;
 		if (rayorigin(&lr, r, TRANS, nd.tspec) == 0) {
-			VCOPY(lr.rdir, r->rdir);
+			VCOPY(lr.rdir, nd.prdir);
 			rayvalue(&lr);
 			scalecolor(lr.rcol, nd.tspec);
+			multcolor(lr.rcol, nd.mcolor);	/* modified by color */
 			addcolor(r->rcol, lr.rcol);
+			transtest *= bright(lr.rcol);
+			transdist = r->rot + lr.rt;
 		}
 	}
 	if (r->crtype & SHADOW)			/* the rest is shadow */
@@ -226,10 +239,13 @@ register RAY  *r;
 			scalecolor(ctmp, nd.tdiff);
 		else
 			scalecolor(ctmp, nd.trans);
-		multcolor(ctmp, nd.mcolor);
+		multcolor(ctmp, nd.mcolor);	/* modified by color */
 		addcolor(r->rcol, ctmp);
 		flipsurface(r);
 	}
 					/* add direct component */
 	direct(r, dirnorm, &nd);
+					/* check distance */
+	if (transtest > bright(r->rcol))
+		r->rt = transdist;
 }