--- ray/src/rt/source.c	1991/07/30 18:23:41	1.40
+++ ray/src/rt/source.c	1991/08/12 08:20:49	1.42
@@ -1,4 +1,4 @@
-/* Copyright (c) 1990 Regents of the University of California */
+/* Copyright (c) 1991 Regents of the University of California */
 
 #ifndef lint
 static char SCCSid[] = "$SunId$ LBL";
@@ -164,8 +164,10 @@ register int  sn;		/* source number */
 	if (source[sn].sflags & SDISTANT) {
 		if (source[sn].sflags & SSPOT) {	/* check location */
 			for (i = 0; i < 3; i++)
-				vd[i] = sr->rorg[i] - source[sn].sl.s->aim[i];
+				vd[i] = source[sn].sl.s->aim[i] - sr->rorg[i];
 			d = DOT(sr->rdir,vd);
+			if (d <= FTINY)
+				return(0.0);
 			d = DOT(vd,vd) - d*d;
 			if (PI*d > source[sn].sl.s->siz)
 				return(0.0);
@@ -245,6 +247,7 @@ RAY  *r;			/* ray that hit surface */
 int  (*f)();			/* direct component coefficient function */
 char  *p;			/* data for f */
 {
+	extern int  (*trace)();
 	extern double  pow();
 	register int  sn;
 	int  nshadcheck, ncnts;
@@ -314,6 +317,8 @@ char  *p;			/* data for f */
 				source[cntord[sn].sno].sflags & SFOLLOW )) {
 						/* follow entire path */
 			raycont(&sr);
+			if (trace != NULL)
+				(*trace)(&sr);	/* trace execution */
 			if (bright(sr.rcol) <= FTINY)
 				continue;	/* missed! */
 			copycolor(srccnt[cntord[sn].sno].val, sr.rcol);