--- ray/src/rt/rv2.c	1994/02/28 09:24:43	2.24
+++ ray/src/rt/rv2.c	1994/12/21 09:52:03	2.27
@@ -1,4 +1,4 @@
-/* Copyright (c) 1993 Regents of the University of California */
+/* Copyright (c) 1994 Regents of the University of California */
 
 #ifndef lint
 static char SCCSid[] = "$SunId$ LBL";
@@ -140,6 +140,16 @@ char  *s;
 	else {
 		nv.horiz = ourview.horiz; nv.vert = ourview.vert;
 	}
+	sprintf(buf, "fore and aft clipping plane (%.6g %.6g): ",
+			ourview.vfore, ourview.vaft);
+	(*dev->comout)(buf);
+	(*dev->comin)(buf, NULL);
+	if (buf[0] == CTRL('C')) return;
+	if (sscanf(buf, "%lf %lf", &nv.vfore, &nv.vaft) == 2)
+		change++;
+	else {
+		nv.vfore = ourview.vfore; nv.vaft = ourview.vaft;
+	}
 	sprintf(buf, "view shift and lift (%.6g %.6g): ",
 			ourview.hoff, ourview.voff);
 	(*dev->comout)(buf);
@@ -350,12 +360,13 @@ char  *s;
 	register PNODE  *p = &ptrunk;
 	int  adapt = 0;
 	double  e = 1.0;
-start:
+
 	for (cp = s; isspace(*cp); cp++)
 		;
 	if (*cp == '@') {
 		adapt++;
-		goto start;
+		while (isspace(*++cp))
+			;
 	}
 	if (*cp == '\0') {		/* normalize to point */
 		if (dev->getcur == NULL)
@@ -489,11 +500,12 @@ register char  *s;
 	extern int  do_irrad;
 	extern double  specjitter;
 	extern double  specthresh;
+	extern int  backvis;
 	char  buf[128];
 	
 	if (s[0] == '\0') {
 		(*dev->comout)(
-		"aa ab ad ar as av b dc di dj ds dt i lr lw ps pt sj st: ");
+		"aa ab ad ar as av b dc di dj ds dt i lr lw ps pt sj st bv: ");
 		(*dev->comin)(buf, NULL);
 		s = buf;
 	}
@@ -532,8 +544,19 @@ register char  *s;
 			goto badparam;
 		}
 		break;
-	case 'b':			/* black and white */
-		getparam(s+1, "black and white", 'b', &greyscale);
+	case 'b':			/* back faces or black and white */
+		switch (s[1]) {
+		case 'v':			/* back face visibility */
+			getparam(s+2, "back face visibility", 'b', &backvis);
+			break;
+		case '\0':			/* black and white */
+		case 'y': case 'Y': case 't': case 'T': case '1': case '+':
+		case 'n': case 'N': case 'f': case 'F': case '0': case '-':
+			getparam(s+1, "black and white", 'b', &greyscale);
+			break;
+		default:
+			goto badparam;
+		}
 		break;
 	case 'i':			/* irradiance */
 		getparam(s+1, "irradiance", 'b', &do_irrad);
@@ -609,6 +632,8 @@ char  *s;
 	int  x, y;
 	RAY  thisray;
 
+	thisray.rmax = 0.0;
+
 	if (!sscanvec(s, thisray.rorg) ||
 			!sscanvec(sskip(sskip(sskip(s))), thisray.rdir)) {
 
@@ -618,8 +643,8 @@ char  *s;
 		if ((*dev->getcur)(&x, &y) == ABORT)
 			return;
 
-		if (viewray(thisray.rorg, thisray.rdir, &ourview,
-				(x+.5)/hresolu, (y+.5)/vresolu) < 0) {
+		if ((thisray.rmax = viewray(thisray.rorg, thisray.rdir,
+			&ourview, (x+.5)/hresolu, (y+.5)/vresolu)) < -FTINY) {
 			error(COMMAND, "not on image");
 			return;
 		}