--- ray/src/rt/rpict.c	1990/06/26 09:00:12	1.21
+++ ray/src/rt/rpict.c	1990/11/01 12:06:01	1.23
@@ -141,7 +141,8 @@ char  *zfile, *oldfile;
 	fputresolu(YMAJOR|YDECR, hresolu, vresolu, stdout);
 					/* recover file and compute first */
 	i = salvage(oldfile);
-	if (zfd != -1 && lseek(zfd, (long)i*hresolu*sizeof(float), 0) == -1)
+	if (zfd != -1 && i > 0 &&
+			lseek(zfd, (long)i*hresolu*sizeof(float), 0) == -1)
 		error(SYSTEM, "z file seek error in render");
 	ypos = vresolu-1 - i;
 	fillscanline(scanbar[0], zbar[0], hresolu, ypos, psample);
@@ -320,8 +321,11 @@ int  x, y;			/* pixel position */
 {
 	static RAY  thisray;	/* our ray for this pixel */
 
-	viewray(thisray.rorg, thisray.rdir, &ourview,
-			(x+pixjitter())/hresolu, (y+pixjitter())/vresolu);
+	if (viewray(thisray.rorg, thisray.rdir, &ourview,
+			(x+pixjitter())/hresolu, (y+pixjitter())/vresolu) < 0) {
+		setcolor(col, 0.0, 0.0, 0.0);
+		return(0.0);
+	}
 
 	rayorigin(&thisray, NULL, PRIMARY, 1.0);