--- ray/src/common/bsdf_t.c	2011/07/07 15:25:09	3.19
+++ ray/src/common/bsdf_t.c	2011/08/22 18:21:05	3.23
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: bsdf_t.c,v 3.19 2011/07/07 15:25:09 greg Exp $";
+static const char RCSid[] = "$Id: bsdf_t.c,v 3.23 2011/08/22 18:21:05 greg Exp $";
 #endif
 /*
  *  bsdf_t.c
@@ -26,11 +26,13 @@ typedef int	SDtreCallback(float val, const double *cmi
 
 					/* reference width maximum (1.0) */
 static const unsigned	iwbits = sizeof(unsigned)*4;
-static const unsigned	iwmax = (1<<(sizeof(unsigned)*4))-1;
+static const unsigned	iwmax = 1<<(sizeof(unsigned)*4);
 					/* maximum cumulative value */
 static const unsigned	cumlmax = ~0;
 					/* constant z-vector */
 static const FVECT	zvec = {.0, .0, 1.};
+					/* quantization value */
+static double		quantum = 1./256.;
 
 /* Struct used for our distribution-building callback */
 typedef struct {
@@ -614,15 +616,18 @@ SDgetTreCDist(const FVECT inVec, SDComponent *sdc)
 	if ((inVec == NULL) | (sdc == NULL) ||
 			(sdt = (SDTre *)sdc->dist) == NULL)
 		return NULL;
-	if (sdt->st->ndim == 3)		/* isotropic BSDF? */
+	if (sdt->st->ndim == 3) {	/* isotropic BSDF? */
 		inCoord[0] = .5 - .5*sqrt(inVec[0]*inVec[0] + inVec[1]*inVec[1]);
-	else if (sdt->st->ndim == 4)
+	} else if (sdt->st->ndim == 4) {
 		SDdisk2square(inCoord, -inVec[0], -inVec[1]);
-	else
+	} else
 		return NULL;		/* should be internal error */
+					/* quantize to avoid f.p. errors */
+	for (i = sdt->st->ndim - 2; i--; )
+		inCoord[i] = floor(inCoord[i]/quantum)*quantum + .5*quantum;
 	cdlast = NULL;			/* check for direction in cache list */
 	for (cd = (SDTreCDst *)sdc->cdList; cd != NULL;
-				cdlast = cd, cd = (SDTreCDst *)cd->next) {
+					cdlast = cd, cd = cd->next) {
 		for (i = sdt->st->ndim - 2; i--; )
 			if ((cd->clim[i][0] > inCoord[i]) |
 					(inCoord[i] >= cd->clim[i][1]))
@@ -634,7 +639,7 @@ SDgetTreCDist(const FVECT inVec, SDComponent *sdc)
 		cdlast = cd = make_cdist(sdt, inCoord);
 	if (cdlast != NULL) {		/* move entry to head of cache list */
 		cdlast->next = cd->next;
-		cd->next = sdc->cdList;
+		cd->next = (SDTreCDst *)sdc->cdList;
 		sdc->cdList = (SDCDst *)cd;
 	}
 	return (SDCDst *)cd;		/* ready to go */
@@ -841,6 +846,8 @@ get_extrema(SDSpectralDF *df)
 	double	stepWidth, dhemi, bmin[4], bmax[4];
 
 	stepWidth = SDsmallestLeaf(st);
+	if (quantum > stepWidth)	/* adjust quantization factor */
+		quantum = stepWidth;
 	df->minProjSA = M_PI*stepWidth*stepWidth;
 	if (stepWidth < .03125)
 		stepWidth = .03125;	/* 1/32 resolution good enough */