--- ray/src/rt/func.c	1992/01/04 19:53:25	2.4
+++ ray/src/rt/func.c	1992/09/26 08:10:41	2.7
@@ -54,12 +54,13 @@ int  dofwd;
 					/* check to see if done already */
 	if ((f = (MFUNC *)m->os) != NULL)
 		return(f);
+	fobj = NULL; fray = NULL;
 	if (initfile[0]) {		/* initialize on first call */
 		setcontext("");
 		scompile("Dx=$1;Dy=$2;Dz=$3;", NULL, 0);
 		scompile("Nx=$4;Ny=$5;Nz=$6;", NULL, 0);
 		scompile("Px=$7;Py=$8;Pz=$9;", NULL, 0);
-		scompile("T=$10;Rdot=$11;", NULL, 0);
+		scompile("T=$10;Ts=$25;Rdot=$11;", NULL, 0);
 		scompile("S=$12;Tx=$13;Ty=$14;Tz=$15;", NULL, 0);
 		scompile("Ix=$16;Iy=$17;Iz=$18;", NULL, 0);
 		scompile("Jx=$19;Jy=$20;Jz=$21;", NULL, 0);
@@ -80,12 +81,12 @@ int  dofwd;
 	if (i == 1 && arg[ff][0] == '.')
 		setcontext(f->ctx = "");	/* "." means no file */
 	else {
-		strcpy(sbuf,m->oargs.sarg[ff]);	/* file name is context */
+		strcpy(sbuf,arg[ff]);	/* file name is context */
 		if (i > LCALSUF && !strcmp(sbuf+i-LCALSUF, CALSUF))
 			sbuf[i-LCALSUF] = '\0';	/* remove suffix */
 		setcontext(f->ctx = savestr(sbuf));
 		if (!vardefined(REFVNAME)) {	/* file loaded? */
-			loadfunc(m->oargs.sarg[ff]);
+			loadfunc(arg[ff]);
 			varset(REFVNAME, '=', 1.0);
 		} else				/* reference_count++ */
 			varset(REFVNAME, '=', varvalue(REFVNAME)+1.0);
@@ -211,6 +212,9 @@ l_arg()				/* return nth real argument */
 	extern double  argument();
 	register int  n;
 
+	if (fobj == NULL)
+		syntax("arg(n) used in constant expression");
+
 	n = argument(1) + .5;		/* round to integer */
 
 	if (n < 1)
@@ -249,6 +253,9 @@ register int  n;
 	double  sum;
 	register RAY  *r;
 
+	if (fray == NULL)
+		syntax("ray parameter used in constant expression");
+
 	if (--n < 0)
 		goto badchan;
 
@@ -273,14 +280,14 @@ register int  n;
 				fray->rop[2]*funcxf.xfm[2][n-6] +
 					     funcxf.xfm[3][n-6] );
 
-	if (n == 9) {			/* distance */
-
+	if (n == 9) {			/* total distance */
 		sum = fray->rot;
 		for (r = fray->parent; r != NULL; r = r->parent)
 			sum += r->rot;
 		return(sum * funcxf.sca);
 
 	}
+
 	if (n == 10)			/* dot product (range [-1,1]) */
 		return(	fray->rod <= -1.0 ? -1.0 :
 			fray->rod >= 1.0 ? 1.0 :
@@ -300,6 +307,14 @@ register int  n;
 
 	if (n < 24)			/* k unit vector */
 		return(funcxf.xfm[2][n-21] / funcxf.sca);
+
+	if (n == 24) {			/* single ray (shadow) distance */
+		sum = fray->rot;
+		for (r = fray->parent; r != NULL && r->crtype&SHADOW;
+				r = r->parent)
+			sum += r->rot;
+		return(sum * funcxf.sca);
+	}
 badchan:
 	error(USER, "illegal channel number");
 }