--- ray/src/rt/ambcomp.c	2014/05/02 21:58:50	2.46
+++ ray/src/rt/ambcomp.c	2014/05/07 01:16:02	2.49
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: ambcomp.c,v 2.46 2014/05/02 21:58:50 greg Exp $";
+static const char	RCSid[] = "$Id: ambcomp.c,v 2.49 2014/05/07 01:16:02 greg Exp $";
 #endif
 /*
  * Routines to compute "ambient" values using Monte Carlo
@@ -50,6 +50,7 @@ static const int  adjacent_trifl[8] = {
 
 typedef struct {
 	COLOR	v;		/* hemisphere sample value */
+	float	d;		/* reciprocal distance (1/rt) */
 	FVECT	p;		/* intersection point */
 } AMBSAMP;		/* sample value */
 
@@ -207,20 +208,16 @@ ambsample(				/* initial ambient division sample */
 	AMBSAMP	*ap = &ambsam(hp,i,j);
 	RAY	ar;
 					/* generate hemispherical sample */
-	if (!getambsamp(&ar, hp, i, j, 0))
-		goto badsample;
-					/* limit vertex distance */
+	if (!getambsamp(&ar, hp, i, j, 0) || ar.rt <= FTINY) {
+		memset(ap, 0, sizeof(AMBSAMP));
+		return(NULL);
+	}
+	ap->d = 1.0/ar.rt;		/* limit vertex distance */
 	if (ar.rt > 10.0*thescene.cusize)
 		ar.rt = 10.0*thescene.cusize;
-	else if (ar.rt <= FTINY)	/* should never happen! */
-		goto badsample;
 	VSUM(ap->p, ar.rorg, ar.rdir, ar.rt);
 	copycolor(ap->v, ar.rcol);
 	return(ap);
-badsample:
-	setcolor(ap->v, 0., 0., 0.);
-	VCOPY(ap->p, hp->rp->rop);
-	return(NULL);
 }
 
 
@@ -317,51 +314,42 @@ static uby8 *
 vertex_flags(AMBHEMI *hp)
 {
 	uby8	*vflags = (uby8 *)calloc(hp->ns*hp->ns, sizeof(uby8));
-	double	*dist2a = (double *)malloc(sizeof(double)*hp->ns);
 	uby8	*vf;
+	AMBSAMP	*ap;
 	int	i, j;
 
-	if ((vflags == NULL) | (dist2a == NULL))
+	if (vflags == NULL)
 		error(SYSTEM, "out of memory in vertex_flags()");
-	vf = vflags;		/* compute distances along first row */
-	for (j = 0; j < hp->ns; j++) {
-		dist2a[j] = dist2(ambsam(hp,0,j).p, hp->rp->rop);
-		++vf;
-		if (!j) continue;
-		if (dist2a[j] >= dist2a[j-1])
-			vf[0] |= 1<<VDB_x;
+	vf = vflags;
+	ap = hp->sa;		/* compute farthest along first row */
+	for (j = 0; j < hp->ns-1; j++, vf++, ap++)
+		if (ap[0].d <= ap[1].d)
+			vf[0] |= 1<<VDB_X;
 		else
-			vf[-1] |= 1<<VDB_X;
-	}
+			vf[1] |= 1<<VDB_x;
+	++vf; ++ap;
 				/* flag subsequent rows */
 	for (i = 1; i < hp->ns; i++) {
-	    double	d2n = dist2(ambsam(hp,i,0).p, hp->rp->rop);
-	    for (j = 0; j < hp->ns-1; j++) {
-		double	d2 = d2n;
-		if (d2 >= dist2a[j])	/* row before */
+	    for (j = 0; j < hp->ns-1; j++, vf++, ap++) {
+		if (ap[0].d <= ap[-hp->ns].d)	/* row before */
 			vf[0] |= 1<<VDB_y;
 		else
 			vf[-hp->ns] |= 1<<VDB_Y;
-		dist2a[j] = d2n;
-		if (d2 >= dist2a[j+1])	/* diagonal we care about */
+		if (ap[0].d <= ap[1-hp->ns].d)	/* diagonal we care about */
 			vf[0] |= 1<<VDB_Xy;
 		else
 			vf[1-hp->ns] |= 1<<VDB_xY;
-		d2n = dist2(ambsam(hp,i,j+1).p, hp->rp->rop);
-		if (d2 >= d2n)		/* column after */
+		if (ap[0].d <= ap[1].d)		/* column after */
 			vf[0] |= 1<<VDB_X;
 		else
 			vf[1] |= 1<<VDB_x;
-		++vf;
 	    }
-	    if (d2n >= dist2a[j])	/* final column edge */
+	    if (ap[0].d <= ap[-hp->ns].d)	/* final column edge */
 		vf[0] |= 1<<VDB_y;
 	    else
 		vf[-hp->ns] |= 1<<VDB_Y;
-	    dist2a[j] = d2n;
-	    ++vf;
+	    ++vf; ++ap;
 	}
-	free(dist2a);
 	return(vflags);
 }
 
@@ -730,6 +718,39 @@ ambdirgrad(AMBHEMI *hp, FVECT uv[2], float dg[2])
 }
 
 
+/* Compute potential light leak direction flags for cache value */
+static uint32
+ambcorral(AMBHEMI *hp, FVECT uv[2], const double r0, const double r1)
+{
+	uint32	flgs = 0;
+	int	i, j;
+					/* circle around perimeter */
+	for (i = 0; i < hp->ns; i++)
+	    for (j = 0; j < hp->ns; j += !i|(i==hp->ns-1) ? 1 : hp->ns-1) {
+		AMBSAMP	*ap = &ambsam(hp,i,j);
+		FVECT	vec;
+		double	u, v;
+		double	ang;
+		int	abp;
+		if (ap->d <= FTINY)
+			continue;
+		VSUB(vec, ap->p, hp->rp->rop);
+		u = DOT(vec, uv[0]) * ap->d;
+		v = DOT(vec, uv[1]) * ap->d;
+		if ((r0*r0*u*u + r1*r1*v*v) * ap->d*ap->d <= 1.0)
+			continue;	/* occluder outside ellipse */
+		ang = atan2a(v, u);	/* else set direction flags */
+		ang += 2.0*PI*(ang < 0);
+		ang *= 16./PI;
+		if ((ang < .5) | (ang >= 31.5))
+			flgs |= 0x80000001;
+		else
+			flgs |= 3L<<(int)(ang-.5);
+	    }
+	return(flgs);
+}
+
+
 int
 doambient(				/* compute ambient component */
 	COLOR	rcol,			/* input/output color */
@@ -738,7 +759,8 @@ doambient(				/* compute ambient component */
 	FVECT	uv[2],			/* returned (optional) */
 	float	ra[2],			/* returned (optional) */
 	float	pg[2],			/* returned (optional) */
-	float	dg[2]			/* returned (optional) */
+	float	dg[2],			/* returned (optional) */
+	uint32	*crlp			/* returned (optional) */
 )
 {
 	AMBHEMI	*hp = inithemi(rcol, r, wt);
@@ -758,6 +780,8 @@ doambient(				/* compute ambient component */
 		pg[0] = pg[1] = 0.0;
 	if (dg != NULL)
 		dg[0] = dg[1] = 0.0;
+	if (crlp != NULL)
+		*crlp = 0;
 					/* sample the hemisphere */
 	acol[0] = acol[1] = acol[2] = 0.0;
 	cnt = 0;
@@ -827,6 +851,8 @@ doambient(				/* compute ambient component */
 			if (ra[0] > maxarad)
 				ra[0] = maxarad;
 		}
+		if (crlp != NULL)	/* flag encroached directions */
+			*crlp = ambcorral(hp, uv, ra[0]*ambacc, ra[1]*ambacc);
 		if (pg != NULL) {	/* cap gradient if necessary */
 			d = pg[0]*pg[0]*ra[0]*ra[0] + pg[1]*pg[1]*ra[1]*ra[1];
 			if (d > 1.0) {