--- ray/src/rt/dielectric.c	2013/08/07 05:10:09	2.23
+++ ray/src/rt/dielectric.c	2014/05/10 17:43:01	2.24
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: dielectric.c,v 2.23 2013/08/07 05:10:09 greg Exp $";
+static const char	RCSid[] = "$Id: dielectric.c,v 2.24 2014/05/10 17:43:01 greg Exp $";
 #endif
 /*
  *  dielectric.c - shading function for transparent materials.
@@ -64,10 +64,10 @@ mylog(		/* special log for extinction coefficients */
 }
 
 
-extern int
+int
 m_dielectric(	/* color a ray which hit a dielectric interface */
 	OBJREC  *m,
-	register RAY  *r
+	RAY  *r
 )
 {
 	double  cos1, cos2, nratio;
@@ -81,7 +81,7 @@ m_dielectric(	/* color a ray which hit a dielectric in
 	FVECT  dnorm;
 	double  d1, d2;
 	RAY  p;
-	register int  i;
+	int  i;
 
 	if (m->oargs.nfargs != (m->otype==MAT_DIELECTRIC ? 5 : 8))
 		objerror(m, USER, "bad arguments");
@@ -94,7 +94,8 @@ m_dielectric(	/* color a ray which hit a dielectric in
 		VCOPY(dnorm, r->ron);
 		cos1 = r->rod;
 	}
-	flatsurface = !hastexture && r->ro != NULL && isflat(r->ro->otype);
+	flatsurface = r->ro != NULL && isflat(r->ro->otype) &&
+			!hastexture | (r->crtype & AMBIENT);
 
 						/* index of refraction */
 	if (m->otype == MAT_DIELECTRIC)
@@ -199,8 +200,8 @@ m_dielectric(	/* color a ray which hit a dielectric in
 				addcolor(r->rcol, p.rcol);
 						/* virtual distance */
 				if (flatsurface ||
-					(1.-FTINY <= nratio &&
-						nratio <= 1.+FTINY)) {
+					(1.-FTINY <= nratio) &
+						(nratio <= 1.+FTINY)) {
 					transtest = 2*bright(p.rcol);
 					transdist = r->rot + p.rt;
 				}
@@ -380,7 +381,7 @@ disperse(  /* check light sources for dispersion */
 
 static int
 lambda(			/* compute lambda for material */
-	register OBJREC  *m,
+	OBJREC  *m,
 	FVECT  v2,
 	FVECT  dv,
 	FVECT  lr