--- ray/src/rt/aniso.c	1992/05/20 14:23:45	2.20
+++ ray/src/rt/aniso.c	1994/01/12 16:46:32	2.27
@@ -19,9 +19,11 @@ static char SCCSid[] = "$SunId$ LBL";
 extern double  specthresh;		/* specular sampling threshold */
 extern double  specjitter;		/* specular sampling jitter */
 
+static  agaussamp(), getacoords();
+
 /*
- *	This anisotropic reflection model uses a variant on the
- *  exponential Gaussian used in normal.c.
+ *	This routine implements the anisotropic Gaussian
+ *  model described by Ward in Siggraph `92 article.
  *	We orient the surface towards the incoming ray, so a single
  *  surface can be used to represent an infinitely thin object.
  *
@@ -34,8 +36,6 @@ extern double  specjitter;		/* specular sampling jitte
  *  8  red 	grn	blu	rspec	u-rough	v-rough	trans	tspec
  */
 
-#define  BSPEC(m)	(6.0)		/* specularity parameter b */
-
 				/* specularity flags */
 #define  SP_REFL	01		/* has reflected specular component */
 #define  SP_TRAN	02		/* has transmitted specular */
@@ -109,15 +109,15 @@ double  omega;			/* light source size */
 		h[0] = ldir[0] - np->rp->rdir[0];
 		h[1] = ldir[1] - np->rp->rdir[1];
 		h[2] = ldir[2] - np->rp->rdir[2];
-		normalize(h);
 						/* ellipse */
 		dtmp1 = DOT(np->u, h);
 		dtmp1 *= dtmp1 / au2;
 		dtmp2 = DOT(np->v, h);
 		dtmp2 *= dtmp2 / av2;
 						/* gaussian */
-		dtmp = (dtmp1 + dtmp2) / (1.0 + DOT(np->pnorm, h));
-		dtmp = exp(-2.0*dtmp) * 1.0/(4.0*PI)
+		dtmp = DOT(np->pnorm, h);
+		dtmp = (dtmp1 + dtmp2) / (dtmp*dtmp);
+		dtmp = exp(-dtmp) * (0.25/PI)
 				* sqrt(ldot/(np->pdot*au2*av2));
 						/* worth using? */
 		if (dtmp > FTINY) {
@@ -155,15 +155,15 @@ double  omega;			/* light source size */
 			dtmp = 1.0 - dtmp1*dtmp1/dtmp;
 			if (dtmp > FTINY*FTINY) {
 				dtmp1 = DOT(h,np->u);
-				dtmp1 = dtmp1*dtmp1 / au2;
+				dtmp1 *= dtmp1 / au2;
 				dtmp2 = DOT(h,np->v);
-				dtmp2 = dtmp2*dtmp2 / av2;
+				dtmp2 *= dtmp2 / av2;
 				dtmp = (dtmp1 + dtmp2) / dtmp;
 			}
 		} else
 			dtmp = 0.0;
 						/* gaussian */
-		dtmp = exp(-dtmp) * 1.0/PI
+		dtmp = exp(-dtmp) * (1.0/PI)
 				* sqrt(-ldot/(np->pdot*au2*av2));
 						/* worth using? */
 		if (dtmp > FTINY) {
@@ -181,12 +181,11 @@ register OBJREC  *m;
 register RAY  *r;
 {
 	ANISODAT  nd;
-	double  dtmp;
 	COLOR  ctmp;
 	register int  i;
 						/* easy shadow test */
 	if (r->crtype & SHADOW)
-		return;
+		return(1);
 
 	if (m->oargs.nfargs != (m->otype == MAT_TRANS2 ? 8 : 6))
 		objerror(m, USER, "bad number of real arguments");
@@ -220,15 +219,8 @@ register RAY  *r;
 		else
 			setcolor(nd.scolor, 1.0, 1.0, 1.0);
 		scalecolor(nd.scolor, nd.rspec);
-						/* improved model */
-		dtmp = exp(-BSPEC(m)*nd.pdot);
-		for (i = 0; i < 3; i++)
-			colval(nd.scolor,i) += (1.0-colval(nd.scolor,i))*dtmp;
-		nd.rspec += (1.0-nd.rspec)*dtmp;
 						/* check threshold */
-		if (specthresh > FTINY &&
-				(specthresh >= 1.-FTINY ||
-				specthresh + .05 - .1*frandom() > nd.rspec))
+		if (specthresh >= nd.rspec-FTINY)
 			nd.specfl |= SP_RBLT;
 						/* compute refl. direction */
 		for (i = 0; i < 3; i++)
@@ -245,9 +237,7 @@ register RAY  *r;
 		if (nd.tspec > FTINY) {
 			nd.specfl |= SP_TRAN;
 							/* check threshold */
-			if (specthresh > FTINY &&
-					(specthresh >= 1.-FTINY ||
-				specthresh + .05 - .1*frandom() > nd.tspec))
+			if (specthresh >= nd.tspec-FTINY)
 				nd.specfl |= SP_TBLT;
 			if (DOT(r->pert,r->pert) <= FTINY*FTINY) {
 				VCOPY(nd.prdir, r->rdir);
@@ -297,6 +287,8 @@ register RAY  *r;
 	}
 					/* add direct component */
 	direct(r, diraniso, &nd);
+
+	return(1);
 }