--- ray/src/rt/raycalls.c	2005/04/19 01:15:06	2.11
+++ ray/src/rt/raycalls.c	2005/06/15 15:36:52	2.14
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: raycalls.c,v 2.11 2005/04/19 01:15:06 greg Exp $";
+static const char	RCSid[] = "$Id: raycalls.c,v 2.14 2005/06/15 15:36:52 greg Exp $";
 #endif
 /*
  *  raycalls.c - interface for running Radiance rendering as a library
@@ -90,6 +90,7 @@ static const char	RCSid[] = "$Id: raycalls.c,v 2.11 20
  */
 
 #include <string.h>
+#include <time.h>
 
 #include  "ray.h"
 #include  "source.h"
@@ -118,6 +119,8 @@ void	(*addobjnotify[8])() = {ambnotify, NULL};
 
 int	do_irrad = 0;			/* compute irradiance? */
 
+int	rand_samp = 0;			/* pure Monte Carlo sampling? */
+
 double	dstrsrc = 0.0;			/* square source distribution */
 double	shadthresh = .03;		/* shadow threshold */
 double	shadcert = .75;			/* shadow certainty */
@@ -163,6 +166,7 @@ ray_init(			/* initialize ray-tracing calculation */
 		initotypes();
 					/* initialize urand */
 	initurand(2048);
+	srandom(rand_samp ? (long)time(0) : 0L);
 					/* read scene octree */
 	readoct(octname = otnm, ~(IO_FILES|IO_INFO), &thescene, NULL);
 	nsceneobjs = nobjects;
@@ -179,7 +183,7 @@ ray_trace(			/* trace a primary ray */
 )
 {
 	rayorigin(r, PRIMARY, NULL, NULL);
-	samplendx++;
+	samplendx = rand_samp ? random() : samplendx+1;
 	rayvalue(r);		/* assumes origin and direction are set */
 }