--- ray/src/util/rfluxmtx.c	2017/04/13 22:47:17	2.44
+++ ray/src/util/rfluxmtx.c	2019/03/03 17:01:13	2.47
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: rfluxmtx.c,v 2.44 2017/04/13 22:47:17 greg Exp $";
+static const char RCSid[] = "$Id: rfluxmtx.c,v 2.47 2019/03/03 17:01:13 greg Exp $";
 #endif
 /*
  * Calculate flux transfer matrix or matrices using rcontrib
@@ -18,7 +18,9 @@ static const char RCSid[] = "$Id: rfluxmtx.c,v 2.44 20
 #include "triangulate.h"
 #include "platform.h"
 
-#define MAXRCARG	512
+#ifndef MAXRCARG
+#define MAXRCARG	10000
+#endif
 
 char		*progname;		/* global argv[0] */
 
@@ -659,7 +661,7 @@ sample_origin(PARAMS *p, FVECT orig, const FVECT rdir,
 		projsa[i] = -DOT(sp->snrm, rdir) * sp->area;
 		tarea += projsa[i] *= (double)(projsa[i] > FTINY);
 	}
-	if (tarea <= FTINY) {		/* wrong side of sender? */
+	if (tarea < 0) {		/* wrong side of sender? */
 		fputs(progname, stderr);
 		fputs(": internal - sample behind all sender elements!\n",
 				stderr);
@@ -760,11 +762,13 @@ sample_reinhart(PARAMS *p, int b, FILE *fp)
 	}
 	while (n--) {			/* stratified sampling */
 		SDmultiSamp(samp3, 3, (n+frandom())/sampcnt);
+		if (row >= RowMax-1)	/* avoid crowding at zenith */
+			samp3[1] *= samp3[1];
 		alt = (row+samp3[1])*RAH;
 		azi = (2.*PI)*(col+samp3[2]-.5)/rnaz(row);
 		duvw[2] = cos(alt);	/* measured from horizon */
 		duvw[0] = tsin(azi)*duvw[2];
-		duvw[1] = tcos(azi)*duvw[2];
+		duvw[1] = -tcos(azi)*duvw[2];
 		duvw[2] = sqrt(1. - duvw[2]*duvw[2]);
 		for (i = 3; i--; )
 			orig_dir[1][i] = -duvw[0]*p->udir[i] -