--- ray/src/hd/holo.c	1997/11/03 11:03:23	3.2
+++ ray/src/hd/holo.c	1997/11/11 14:40:59	3.4
@@ -104,13 +104,13 @@ HDGRID	*hproto;
 
 
 hdbcoord(gc, hp, i)		/* compute beam coordinates from index */
-BCOORD	gc;		/* returned */
+GCOORD	gc[2];		/* returned */
 register HOLO	*hp;
 register int	i;
 {
 	register int	j, n;
 	int	n2, reverse;
-	BCOORD	g2;
+	GCOORD	g2[2];
 					/* check range */
 	if (i < 1 | i > nbeams(hp))
 		return(0);
@@ -150,9 +150,9 @@ register int	i;
 int
 hdbindex(hp, gc)		/* compute index from beam coordinates */
 register HOLO	*hp;
-register BCOORD	gc;
+register GCOORD	gc[2];
 {
-	BCOORD	g2;
+	GCOORD	g2[2];
 	int	reverse;
 	register int	i, j;
 					/* check ordering and limits */
@@ -178,12 +178,38 @@ register BCOORD	gc;
 }
 
 
+hdcell(cp, hp, gc)		/* compute cell coordinates */
+register FVECT	cp[4];	/* returned (may be passed as FVECT cp[2][2]) */
+HOLO	*hp;
+register GCOORD	*gc;
+{
+	register int	i;
+	register FLOAT	*v;
+	double	d;
+					/* compute each corner */
+	for (i = 0; i < 4; i++) {
+		VCOPY(cp[i], hp->orig);
+		if (gc->w & 1) {
+			v = hp->xv[gc->w>>1];
+			cp[i][0] += *v++; cp[i][1] += *v++; cp[i][2] += *v;
+		}
+		d = (double)( gc->i[0] + (i&1) ) / hp->grid[wg0[gc->w]];
+		v = hp->xv[wg0[gc->w]];
+		cp[i][0] += d * *v++; cp[i][1] += d * *v++; cp[i][2] += d * *v;
+
+		d = (double)( gc->i[1] + (i>>1) ) / hp->grid[wg1[gc->w]];
+		v = hp->xv[wg1[gc->w]];
+		cp[i][0] += d * *v++; cp[i][1] += d * *v++; cp[i][2] += d * *v;
+	}
+}
+
+
 hdlseg(lseg, hp, i)			/* compute line segment for beam */
 register int	lseg[2][3];
 register HOLO	*hp;
 int	i;
 {
-	BCOORD	gc;
+	GCOORD	gc[2];
 	register int	k;
 
 	if (!hdbcoord(gc, hp, i))		/* compute grid coordinates */
@@ -220,7 +246,7 @@ double
 hdray(ro, rd, hp, gc, r)	/* compute ray within a beam */
 FVECT	ro, rd;		/* returned */
 register HOLO	*hp;
-register BCOORD	gc;
+register GCOORD	gc[2];
 BYTE	r[2][2];
 {
 	FVECT	p[2];
@@ -238,7 +264,7 @@ BYTE	r[2][2];
 				hp->grid[wg0[gc[i].w]];
 		v = hp->xv[wg0[gc[i].w]];
 		p[i][0] += d * *v++; p[i][1] += d * *v++; p[i][2] += d * *v;
-		d = (gc[i].i[1] + (1./256.)*(r[i][1]+.5)) /
+		d = ( gc[i].i[1] + (1./256.)*(r[i][1]+.5) ) /
 				hp->grid[wg1[gc[i].w]];
 		v = hp->xv[wg1[gc[i].w]];
 		p[i][0] += d * *v++; p[i][1] += d * *v++; p[i][2] += d * *v;
@@ -253,7 +279,7 @@ BYTE	r[2][2];
 
 double
 hdinter(gc, r, hp, ro, rd)	/* compute ray intersection with section */
-register BCOORD	gc;	/* returned */
+register GCOORD	gc[2];	/* returned */
 BYTE	r[2][2];	/* returned */
 register HOLO	*hp;
 FVECT	ro, rd;		/* rd should be normalized */