--- ray/src/rt/mx_func.c	1991/11/25 09:50:56	2.2
+++ ray/src/rt/mx_func.c	2014/07/08 18:25:00	2.9
@@ -1,18 +1,15 @@
-/* Copyright (c) 1991 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char	RCSid[] = "$Id: mx_func.c,v 2.9 2014/07/08 18:25:00 greg Exp $";
 #endif
-
 /*
  *  mx_func.c - routine for mixture functions.
- *
- *     11/2/88
  */
 
-#include  "ray.h"
+#include "copyright.h"
 
+#include  "ray.h"
 #include  "func.h"
+#include  "rtotypes.h"
 
 /*
  *	A mixture function is specified:
@@ -29,21 +26,25 @@ static char SCCSid[] = "$SunId$ LBL";
  */
 
 
-mx_func(m, r)			/* compute mixture function */
-register OBJREC  *m;
-RAY  *r;
+int
+mx_func(			/* compute mixture function */
+	OBJREC  *m,
+	RAY  *r
+)
 {
-	register int  i;
+	OBJECT	obj;
+	int  i;
 	double  coef;
 	OBJECT  mod[2];
-	register MFUNC  *mf;
+	MFUNC  *mf;
 
 	if (m->oargs.nsargs < 4)
 		objerror(m, USER, "bad # arguments");
+	obj = objndx(m);
 	for (i = 0; i < 2; i++)
 		if (!strcmp(m->oargs.sarg[i], VOIDID))
 			mod[i] = OVOID;
-		else if ((mod[i] = modifier(m->oargs.sarg[i])) == OVOID) {
+		else if ((mod[i] = lastmod(obj, m->oargs.sarg[i])) == OVOID) {
 			sprintf(errmsg, "undefined modifier \"%s\"",
 					m->oargs.sarg[i]);
 			objerror(m, USER, errmsg);
@@ -52,9 +53,14 @@ RAY  *r;
 	setfunc(m, r);
 	errno = 0;
 	coef = evalue(mf->ep[0]);
-	if (errno) {
+	if (errno == EDOM || errno == ERANGE) {
 		objerror(m, WARNING, "compute error");
-		return;
+		return(0);
 	}
-	raymixture(r, mod[0], mod[1], coef);
+	if (raymixture(r, mod[0], mod[1], coef)) {
+		if (m->omod != OVOID)
+			objerror(m, USER, "inappropriate modifier");
+		return(1);
+	}
+	return(0);
 }