--- ray/src/rt/o_cone.c	1990/12/15 15:03:28	1.3
+++ ray/src/rt/o_cone.c	2004/06/28 10:07:17	2.6
@@ -1,25 +1,23 @@
-/* Copyright (c) 1990 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char RCSid[] = "$Id: o_cone.c,v 2.6 2004/06/28 10:07:17 greg Exp $";
 #endif
-
 /*
  *  o_cone.c - routine to determine ray intersection with cones.
- *
- *     2/13/86
  */
 
-#include  "ray.h"
+#include "copyright.h"
 
+#include  "ray.h"
 #include  "otypes.h"
-
+#include  "rtotypes.h"
 #include  "cone.h"
 
 
-o_cone(o, r)			/* intersect ray with cone */
-OBJREC  *o;
-register RAY  *r;
+extern int
+o_cone(			/* intersect ray with cone */
+	OBJREC  *o,
+	register RAY  *r
+)
 {
 	FVECT  rox, rdx;
 	double  a, b, c;
@@ -129,7 +127,14 @@ register RAY  *r;
 			for (i = 0; i < 3; i++)
 				r->ron[i] = (co->al*r->ron[i] - c*co->ad[i])
 						/co->sl;
+		a = DOT(r->ron, r->ron);
+		if (a > 1.+FTINY || a < 1.-FTINY) {
+			c = 1./(.5 + .5*a);     /* avoid numerical error */
+			r->ron[0] *= c; r->ron[1] *= c; r->ron[2] *= c;
+		}
 		r->rod = -DOT(r->rdir, r->ron);
+		r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
+		r->uv[0] = r->uv[1] = 0.0;
 		r->rox = NULL;
 		return(1);			/* good */
 	}