--- ray/src/rt/virtuals.c	1991/06/25 15:48:11	1.11
+++ ray/src/rt/virtuals.c	1991/07/11 16:43:38	1.16
@@ -19,7 +19,10 @@ static char SCCSid[] = "$SunId$ LBL";
 
 #include  "random.h"
 
+#define  MINSAMPLES	5		/* minimum number of pretest samples */
+#define  STESTMAX	30		/* maximum seeks per sample */
 
+
 double  getdisk();
 
 static OBJECT  *vobject;		/* virtual source objects */
@@ -158,14 +161,24 @@ MAT4  pm;
 			return(-1);		/* at source!! */
 		if (source[sn].sflags & SPROX && d > source[sn].sl.prox)
 			return(-1);		/* too far away */
-		ourspot.siz = 2.*PI*(1. - d/sqrt(d*d+maxrad2));
 		ourspot.flen = 0.;
+		if (d*d > maxrad2)
+			ourspot.siz = 2.*PI*(1. - sqrt(1.-maxrad2/(d*d)));
+		else
+			nsflags &= ~SSPOT;
 		if (source[sn].sflags & SSPOT) {
 			copystruct(&theirspot, source[sn].sl.s);
 			multv3(theirspot.aim, source[sn].sl.s->aim, pm);
-			d = ourspot.siz;
-			if (!commonspot(&ourspot, &theirspot, nsloc))
-				return(-1);	/* no overlap */
+			if (nsflags & SSPOT) {
+				ourspot.flen = theirspot.flen;
+				d = ourspot.siz;
+				if (!commonspot(&ourspot, &theirspot, nsloc))
+					return(-1);	/* no overlap */
+			} else {
+				nsflags |= SSPOT;
+				copystruct(&ourspot, &theirspot);
+				d = 2.*ourspot.siz;
+			}
 			if (ourspot.siz < d-FTINY) {	/* it shrunk */
 				d = spotdisk(v, op, &ourspot, nsloc);
 				if (d <= FTINY)
@@ -175,11 +188,10 @@ MAT4  pm;
 					VCOPY(ocent, v);
 				}
 			}
-			ourspot.flen = theirspot.flen;
 		}
 		if (source[sn].sflags & SFLAT) {	/* behind source? */
 			multv3(nsnorm, source[sn].snorm, pm);
-			if (checkspot(&ourspot, nsnorm) < 0)
+			if (!checkspot(&ourspot, nsnorm))
 				return(-1);
 		}
 	}
@@ -195,9 +207,11 @@ MAT4  pm;
 	if (nsflags & SFLAT)
 		VCOPY(source[i].snorm, nsnorm);
 	source[i].ss = source[sn].ss; source[i].ss2 = source[sn].ss2;
-	if ((source[i].sl.s = (SPOT *)malloc(sizeof(SPOT))) == NULL)
-		goto memerr;
-	copystruct(source[i].sl.s, &ourspot);
+	if (nsflags & SSPOT) {
+		if ((source[i].sl.s = (SPOT *)malloc(sizeof(SPOT))) == NULL)
+			goto memerr;
+		copystruct(source[i].sl.s, &ourspot);
+	}
 	if (nsflags & SPROX)
 		source[i].sl.prox = source[sn].sl.prox;
 	source[i].sa.svnext = sn;
@@ -253,7 +267,7 @@ register int  sn;	/* target source number */
 	FVECT  offsdir;
 	double  or, d;
 	int  infront;
-	int  ssn;
+	int  stestlim, ssn;
 	int  nhit, nok;
 	register int  i, n;
 				/* return if pretesting disabled */
@@ -272,19 +286,20 @@ register int  sn;	/* target source number */
 		n = or2/DOT(offsdir,offsdir)*vspretest + .5;
 		infront = DOT(onorm, offsdir) > 0.;
 	}
-	if (n < 1) n = 1;
+	if (n < MINSAMPLES) n = MINSAMPLES;
 #ifdef DEBUG
 	fprintf(stderr, "pretesting source %d in object %s with %d rays\n",
 			sn, o->oname, n);
 #endif
 				/* sample */
 	or = sqrt(or2);
-	ssn = 25*n;
+	stestlim = n*STESTMAX;
+	ssn = 0;
 	nhit = nok = 0;
 	while (n-- > 0) {
 					/* get sample point */
 		do {
-			if (--ssn < 0) {
+			if (ssn >= stestlim) {
 #ifdef DEBUG
 				fprintf(stderr, "\ttoo hard to hit\n");
 #endif
@@ -292,7 +307,8 @@ register int  sn;	/* target source number */
 			}
 			for (i = 0; i < 3; i++)
 				offsdir[i] = or*(1. -
-						2.*urand(931*i+5827+ssn));
+					2.*urand(urind(931*i+5827,ssn)));
+			ssn++;
 			for (i = 0; i < 3; i++)
 				sr.rorg[i] = oc[i] + offsdir[i];
 			d = DOT(offsdir,onorm);