--- ray/src/rt/rpict.c	1991/06/24 16:10:46	1.28
+++ ray/src/rt/rpict.c	1991/09/19 13:55:53	1.32
@@ -41,7 +41,8 @@ double  dstrsrc = 0.0;			/* square source distribution
 double  shadthresh = .05;		/* shadow threshold */
 double  shadcert = .5;			/* shadow certainty */
 int  directrelay = 0;			/* number of source relays */
-int  vspretest = 128;			/* virtual source pretest density */
+int  vspretest = 512;			/* virtual source pretest density */
+int  directinvis = 0;			/* sources invisible? */
 
 int  maxdepth = 6;			/* maximum recursion depth */
 double  minweight = 5e-3;		/* minimum ray weight */
@@ -166,6 +167,10 @@ char  *zfile, *oldfile;
 	pctdone = 100.0*i/vresolu;
 	if (ralrm > 0)			/* report init stats */
 		report();
+#ifndef  BSD
+	else
+#endif
+	signal(SIGALRM, report);
 	ypos = vresolu-1 - i;
 	fillscanline(scanbar[0], zbar[0], hresolu, ypos, psample);
 	ystep = psample;
@@ -187,6 +192,9 @@ char  *zfile, *oldfile;
 							/* fill bar */
 		fillscanbar(scanbar, zbar, hresolu, ypos, ystep);
 							/* write it out */
+#ifndef  BSD
+		signal(SIGALRM, SIG_IGN);	/* don't interrupt writes */
+#endif
 		for (i = ystep; i > 0; i--) {
 			if (zfd != -1 && write(zfd, (char *)zbar[i],
 					hresolu*sizeof(float))
@@ -201,6 +209,10 @@ char  *zfile, *oldfile;
 		pctdone = 100.0*(vresolu-1-ypos)/vresolu;
 		if (ralrm > 0 && time((long *)0) >= tlastrept+ralrm)
 			report();
+#ifndef  BSD
+		else
+			signal(SIGALRM, report);
+#endif
 	}
 						/* clean up */
 	if (zfd != -1) {
@@ -353,7 +365,7 @@ int  x, y;			/* pixel position */
 
 	rayorigin(&thisray, NULL, PRIMARY, 1.0);
 
-	samplendx = 3*y + x;			/* set pixel index */
+	samplendx = pixnumber(x,y,hresolu,vresolu);	/* set pixel index */
 
 	rayvalue(&thisray);			/* trace ray */
 
@@ -412,4 +424,16 @@ char  *oldfile;
 	return(y);
 writerr:
 	error(SYSTEM, "write error in salvage");
+}
+
+
+int
+pixnumber(x, y, xres, yres)		/* compute pixel index (brushed) */
+register int  x, y;
+int  xres, yres;
+{
+	x -= y;
+	while (x < 0)
+		x += xres;
+	return((((x>>2)*yres + y) << 2) + (x & 3));
 }