--- ray/src/hd/rhdisp.c	2004/03/28 20:33:13	3.51
+++ ray/src/hd/rhdisp.c	2008/03/11 02:21:47	3.52
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: rhdisp.c,v 3.51 2004/03/28 20:33:13 schorsch Exp $";
+static const char	RCSid[] = "$Id: rhdisp.c,v 3.52 2008/03/11 02:21:47 greg Exp $";
 #endif
 /*
  * Holodeck display process.
@@ -381,6 +381,18 @@ set_focus(			/* set focus frame */
 	case VT_ANG:
 		vwfocus.horiz = hsiz * odev.v.horiz;
 		vwfocus.vert = vsiz * odev.v.vert;
+		break;
+	case VT_PLS:
+		vwfocus.horiz = hsiz * sin((PI/180./2.)*odev.v.horiz) /
+				(1.0 + cos((PI/180./2.)*odev.v.horiz));
+		vwfocus.horiz *= vwfocus.horiz;
+		vwfocus.horiz = (2.*180./PI)*acos((1. - vwfocus.horiz) /
+						(1. + vwfocus.horiz));
+		vwfocus.vert = vsiz * sin((PI/180./2.)*odev.v.vert) /
+				(1.0 + cos((PI/180./2.)*odev.v.vert));
+		vwfocus.vert *= vwfocus.vert;
+		vwfocus.vert = (2.*180./PI)*acos((1. - vwfocus.vert) /
+						(1. + vwfocus.vert));
 		break;
 	case VT_HEM:
 		vwfocus.horiz = 2.*180./PI*asin(