--- ray/src/rt/rtrace.c	1994/12/20 20:18:34	2.17
+++ ray/src/rt/rtrace.c	1994/12/21 09:52:00	2.18
@@ -61,6 +61,8 @@ double  srcsizerat = .25;		/* maximum ratio source siz
 double  specthresh = .15;		/* specular sampling threshold */
 double  specjitter = 1.;		/* specular sampling jitter */
 
+int  backvis = 1;			/* back face visibility */
+
 int  maxdepth = 6;			/* maximum recursion depth */
 double  minweight = 4e-3;		/* minimum ray weight */