--- ray/src/rt/o_mesh.c	2003/03/11 22:48:20	2.2
+++ ray/src/rt/o_mesh.c	2003/03/12 17:26:58	2.4
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: o_mesh.c,v 2.2 2003/03/11 22:48:20 greg Exp $";
+static const char RCSid[] = "$Id: o_mesh.c,v 2.4 2003/03/12 17:26:58 greg Exp $";
 #endif
 /*
  *  Routines for computing ray intersections with meshes.
@@ -71,20 +71,19 @@ int4		v1, v2;
 	ecp = &edge_cache.cache[((v2<<11 ^ v1) & 0x7fffffff) % EDGE_CACHE_SIZ];
 	if (ecp->v1i != v1 || ecp->v2i != v2) {
 		MESHVERT	tv1, tv2;	/* compute signed volume */
+		FVECT		v2d;
 		double		vol;
 		if (!getmeshvert(&tv1, edge_cache.mi->msh, v1, MT_V) ||
 			    !getmeshvert(&tv2, edge_cache.mi->msh, v2, MT_V))
 			objerror(edge_cache.o, INTERNAL,
 				"missing mesh vertex in signed_volume");
+		VSUB(v2d, tv2.v, r->rorg);
 		vol = (tv1.v[0] - r->rorg[0]) *
-				( (tv2.v[1] - r->rorg[1])*r->rdir[2] -
-				  (tv2.v[2] - r->rorg[2])*r->rdir[1] );
+				(v2d[1]*r->rdir[2] - v2d[2]*r->rdir[1]);
 		vol += (tv1.v[1] - r->rorg[1]) *
-				( (tv2.v[2] - r->rorg[2])*r->rdir[0] -
-				  (tv2.v[0] - r->rorg[0])*r->rdir[2] );
+				(v2d[2]*r->rdir[0] - v2d[0]*r->rdir[2]);
 		vol += (tv1.v[2] - r->rorg[2]) *
-				( (tv2.v[0] - r->rorg[0])*r->rdir[1] -
-				  (tv2.v[1] - r->rorg[1])*r->rdir[0] );
+				(v2d[0]*r->rdir[1] - v2d[1]*r->rdir[0]);
 		if (vol > .0)
 			ecp->signum = 1;
 		else if (vol < .0)
@@ -197,12 +196,16 @@ register RAY	*r;
 		if (normalize(r->pert) != 0.0)
 			for (i = 0; i < 3; i++)
 				r->pert[i] -= r->ron[i];
-	}
+	} else
+		r->pert[0] = r->pert[1] = r->pert[2] = .0;
+
 	if (flags & MT_UV)		/* interpolate uv coordinates */
 		for (i = 0; i < 2; i++)
 			r->uv[i] = wt[0]*tv[0].uv[i] +
 					wt[1]*tv[1].uv[i] +
 					wt[2]*tv[2].uv[i];
+	else
+		r->uv[0] = r->uv[1] = .0;
 
 					/* return hit */
 	return(1);