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root/Development/ray/src/rt/ambcomp.c

Comparing ray/src/rt/ambcomp.c (file contents):
Revision 2.58 by greg, Sun May 11 19:03:37 2014 UTC vs.
Revision 2.105 by greg, Thu Aug 21 20:38:41 2025 UTC

#	Line 21 | Line 21 | static const char      RCSid[] = "$Id$";
21		#include  "ambient.h"
22		#include  "random.h"
23
24	<	#ifdef NEWAMB
24	>	#ifndef MINADIV
25	>	#define MINADIV         7       /* minimum # divisions in each dimension */
26	>	#endif
27	>	#ifndef MINSDIST
28	>	#define MINSDIST        0.2     /* def. min. spacing = 1/5th division */
29	>	#endif
30
26	–	extern void             SDsquare2disk(double ds[2], double seedx, double seedy);
27	–
31		typedef struct {
29	–	COLOR   v;              /* hemisphere sample value */
30	–	float   d;              /* reciprocal distance (1/rt) */
32		FVECT   p;              /* intersection point */
33	+	float   d;              /* reciprocal distance */
34	+	SCOLOR  v;              /* hemisphere sample value */
35		} AMBSAMP;              /* sample value */
36
37		typedef struct {
38		RAY     *rp;            /* originating ray sample */
36	–	FVECT   ux, uy;         /* tangent axis unit vectors */
39		int     ns;             /* number of samples per axis */
40	<	COLOR   acoef;          /* division contribution coefficient */
40	>	int     sampOK;         /* acquired full sample set? */
41	>	int     atyp;           /* RAMBIENT or TAMBIENT */
42	>	SCOLOR  acoef;          /* division contribution coefficient */
43	>	SCOLOR  acol;           /* accumulated color */
44	>	FVECT   onrm;           /* oriented unperturbed surface normal */
45	>	FVECT   ux, uy;         /* tangent axis unit vectors */
46		AMBSAMP sa[1];          /* sample array (extends struct) */
47		}  AMBHEMI;             /* ambient sample hemisphere */
48
#	Line 48 | Line 55 | typedef struct {
55		} FFTRI;                /* vectors and coefficients for Hessian calculation */
56
57
58	<	static AMBHEMI *
59	<	inithemi(                       /* initialize sampling hemisphere */
60	<	COLOR   ac,
61	<	RAY     *r,
62	<	double  wt
58	>	#define XLOTSIZ         512             /* size of used car lot */
59	>	#define CFIRST          0               /* first corner */
60	>	#define COTHER          (CFIRST+4)      /* non-corner sample */
61	>	#define CMAXTARGET      (int)(XLOTSIZ*MINSDIST/(1-MINSDIST))
62	>
63	>	static int
64	>	psample_class(double ss[2])             /* classify patch sample */
65	>	{
66	>	if (ss[0] < MINSDIST) {
67	>	if (ss[1] < MINSDIST)
68	>	return(CFIRST);
69	>	if (ss[1] > 1.-MINSDIST)
70	>	return(CFIRST+2);
71	>	} else if (ss[0] > 1.-MINSDIST) {
72	>	if (ss[1] < MINSDIST)
73	>	return(CFIRST+1);
74	>	if (ss[1] > 1.-MINSDIST)
75	>	return(CFIRST+3);
76	>	}
77	>	return(COTHER);                 /* not in a corner */
78	>	}
79	>
80	>	static void
81	>	trade_patchsamp(double ss[2])           /* trade in problem patch position */
82	>	{
83	>	static float    tradelot[XLOTSIZ][2];
84	>	static int      gterm[COTHER+1];
85	>	double          repl[2];
86	>	int             sclass, rclass;
87	>	int             x;
88	>	re_initialize:                          /* initialize lot? */
89	>	while (gterm[COTHER] < XLOTSIZ) {
90	>	tradelot[gterm[COTHER]][0] = frandom();
91	>	tradelot[gterm[COTHER]][1] = frandom();
92	>	++gterm[COTHER];
93	>	}
94	>	/* get trade-in candidate... */
95	>	sclass = psample_class(ss);     /* submitted corner or not? */
96	>	switch (sclass) {
97	>	case COTHER:                    /* trade mid-edge with corner/any */
98	>	x = irandom( gterm[COTHER-1] > CMAXTARGET
99	>	? gterm[COTHER-1] : XLOTSIZ );
100	>	break;
101	>	case CFIRST:                    /* kick out of first corner */
102	>	x = gterm[CFIRST] + irandom(XLOTSIZ - gterm[CFIRST]);
103	>	break;
104	>	default:                        /* kick out of 2nd-4th corner */
105	>	x = irandom(XLOTSIZ - (gterm[sclass] - gterm[sclass-1]));
106	>	x += (x >= gterm[sclass-1])*(gterm[sclass] - gterm[sclass-1]);
107	>	break;
108	>	}
109	>	if (x >= XLOTSIZ) {             /* uh-oh... trapped in a corner! */
110	>	memset(gterm, 0, sizeof(gterm));
111	>	goto re_initialize;
112	>	}
113	>	repl[0] = tradelot[x][0];       /* save selected replacement (result) */
114	>	repl[1] = tradelot[x][1];
115	>	/* identify replacement class */
116	>	for (rclass = CFIRST; rclass < COTHER; rclass++)
117	>	if (x < gterm[rclass])
118	>	break;          /* repark to keep classes grouped */
119	>	while (rclass > sclass) {       /* replacement group after submitted? */
120	>	tradelot[x][0] = tradelot[gterm[rclass-1]][0];
121	>	tradelot[x][1] = tradelot[gterm[rclass-1]][1];
122	>	x = gterm[--rclass]++;
123	>	}
124	>	while (rclass < sclass) {       /* replacement group before submitted? */
125	>	tradelot[x][0] = tradelot[--gterm[rclass]][0];
126	>	tradelot[x][1] = tradelot[gterm[rclass]][1];
127	>	x = gterm[rclass++];
128	>	}
129	>	tradelot[x][0] = ss[0];         /* complete the trade-in */
130	>	tradelot[x][1] = ss[1];
131	>	ss[0] = repl[0];
132	>	ss[1] = repl[1];
133	>	}
134	>
135	>	#undef XLOTSIZ
136	>	#undef COTHER
137	>	#undef CFIRST
138	>
139	>
140	>	static int
141	>	ambcollision(                           /* proposed direction collides? */
142	>	AMBHEMI *hp,
143	>	int     i,
144	>	int     j,
145	>	RREAL   spt[2]
146		)
147		{
148	<	AMBHEMI *hp;
149	<	double  d;
150	<	int     n, i;
151	<	/* set number of divisions */
152	<	if (ambacc <= FTINY &&
153	<	wt > (d = 0.8*intens(ac)*r->rweight/(ambdiv*minweight)))
154	<	wt = d;                 /* avoid ray termination */
155	<	n = sqrt(ambdiv * wt) + 0.5;
156	<	i = 1 + 5*(ambacc > FTINY);     /* minimum number of samples */
157	<	if (n < i)
158	<	n = i;
159	<	/* allocate sampling array */
160	<	hp = (AMBHEMI *)malloc(sizeof(AMBHEMI) + sizeof(AMBSAMP)*(n*n - 1));
161	<	if (hp == NULL)
162	<	return(NULL);
163	<	hp->rp = r;
164	<	hp->ns = n;
165	<	/* assign coefficient */
166	<	copycolor(hp->acoef, ac);
167	<	d = 1.0/(n*n);
168	<	scalecolor(hp->acoef, d);
169	<	/* make tangent plane axes */
170	<	hp->uy[0] = 0.5 - frandom();
171	<	hp->uy[1] = 0.5 - frandom();
172	<	hp->uy[2] = 0.5 - frandom();
83	<	for (i = 3; i--; )
84	<	if ((-0.6 < r->ron[i]) & (r->ron[i] < 0.6))
85	<	break;
86	<	if (i < 0)
87	<	error(CONSISTENCY, "bad ray direction in inithemi");
88	<	hp->uy[i] = 1.0;
89	<	VCROSS(hp->ux, hp->uy, r->ron);
90	<	normalize(hp->ux);
91	<	VCROSS(hp->uy, r->ron, hp->ux);
92	<	/* we're ready to sample */
93	<	return(hp);
148	>	int     ii, jj;
149	>	/* check existing neighbors */
150	>	for (ii = i-1; ii <= i+1; ii++) {
151	>	if (ii < 0) continue;
152	>	if (ii >= hp->ns) break;
153	>	for (jj = j-1; jj <= j+1; jj++) {
154	>	AMBSAMP *ap;
155	>	FVECT   avec;
156	>	double  dx, dy;
157	>	if (jj < 0) continue;
158	>	if (jj >= hp->ns) break;
159	>	if ((ii==i) & (jj==j)) continue;
160	>	ap = &ambsam(hp,ii,jj);
161	>	if (ap->d <= .5/FHUGE)
162	>	continue;       /* no one home */
163	>	VSUB(avec, ap->p, hp->rp->rop);
164	>	normalize(avec);        /* use diskworld distance */
165	>	dx = DOT(avec, hp->ux) - spt[0];
166	>	dy = DOT(avec, hp->uy) - spt[1];
167	>	if ((dx*dx + dy*dy)*(hp->ns*hp->ns) <
168	>	PI*MINSDIST*MINSDIST)
169	>	return(1);      /* too close */
170	>	}
171	>	}
172	>	return(0);                      /* nothing to worry about */
173		}
174
175
97	–	/* Sample ambient division and apply weighting coefficient */
176		static int
177	<	getambsamp(RAY *arp, AMBHEMI *hp, int i, int j, int n)
177	>	ambsample(                              /* initial ambient division sample */
178	>	AMBHEMI *hp,
179	>	int     i,
180	>	int     j,
181	>	int     n
182	>	)
183		{
184	+	int     trade_ok = (!n & (hp->ns >= 4))*21;
185	+	AMBSAMP *ap = &ambsam(hp,i,j);
186	+	RAY     ar;
187		int     hlist[3], ii;
188	<	double  spt[2], zd;
188	>	double  ss[2];
189	>	RREAL   spt[2];
190	>	double  zd;
191	>	/* generate hemispherical sample */
192		/* ambient coefficient for weight */
193		if (ambacc > FTINY)
194	<	setcolor(arp->rcoef, AVGREFL, AVGREFL, AVGREFL);
194	>	setscolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
195		else
196	<	copycolor(arp->rcoef, hp->acoef);
197	<	if (rayorigin(arp, AMBIENT, hp->rp, arp->rcoef) < 0)
196	>	copyscolor(ar.rcoef, hp->acoef);
197	>	if (rayorigin(&ar, hp->atyp, hp->rp, ar.rcoef) < 0)
198		return(0);
199		if (ambacc > FTINY) {
200	<	multcolor(arp->rcoef, hp->acoef);
201	<	scalecolor(arp->rcoef, 1./AVGREFL);
200	>	smultscolor(ar.rcoef, hp->acoef);
201	>	scalescolor(ar.rcoef, 1./AVGREFL);
202		}
203		hlist[0] = hp->rp->rno;
204	<	hlist[1] = j;
205	<	hlist[2] = i;
206	<	multisamp(spt, 2, urand(ilhash(hlist,3)+n));
207	<	if (!n) {                       /* avoid border samples for n==0 */
208	<	if ((spt[0] < 0.1) | (spt[0] >= 0.9))
209	<	spt[0] = 0.1 + 0.8*frandom();
210	<	if ((spt[1] < 0.1) | (spt[1] >= 0.9))
211	<	spt[1] = 0.1 + 0.8*frandom();
204	>	hlist[1] = AI(hp,i,j);
205	>	hlist[2] = samplendx;
206	>	multisamp(ss, 2, urand(ilhash(hlist,3)+n));
207	>	square2disk(spt, (j+ss[1])/hp->ns, (i+ss[0])/hp->ns);
208	>	/* avoid coincident samples? */
209	>	while (trade_ok-- && ambcollision(hp, i, j, spt)) {
210	>	if (trade_ok) {
211	>	trade_patchsamp(ss);
212	>	} else {                /* punting... */
213	>	ss[0] = MINSDIST + (1-2*MINSDIST)*frandom();
214	>	ss[1] = MINSDIST + (1-2*MINSDIST)*frandom();
215	>	}
216	>	square2disk(spt, (j+ss[1])/hp->ns, (i+ss[0])/hp->ns);
217		}
124	–	SDsquare2disk(spt, (j+spt[1])/hp->ns, (i+spt[0])/hp->ns);
218		zd = sqrt(1. - spt[0]*spt[0] - spt[1]*spt[1]);
219		for (ii = 3; ii--; )
220	<	arp->rdir[ii] = spt[0]*hp->ux[ii] +
220	>	ar.rdir[ii] =   spt[0]*hp->ux[ii] +
221		spt[1]*hp->uy[ii] +
222	<	zd*hp->rp->ron[ii];
223	<	checknorm(arp->rdir);
224	<	dimlist[ndims++] = AI(hp,i,j) + 90171;
225	<	rayvalue(arp);                  /* evaluate ray */
226	<	ndims--;                        /* apply coefficient */
227	<	multcolor(arp->rcol, arp->rcoef);
222	>	zd*hp->onrm[ii];
223	>	checknorm(ar.rdir);
224	>	dimlist[ndims_inc()] = AI(hp,i,j) + 90171;
225	>	rayvalue(&ar);                  /* evaluate ray */
226	>	dec_ndims();
227	>	zd = raydistance(&ar);
228	>	if (zd <= FTINY)
229	>	return(0);              /* should never happen */
230	>	smultscolor(ar.rcol, ar.rcoef); /* apply coefficient */
231	>	if (zd*ap->d < 1.0)             /* new/closer distance? */
232	>	ap->d = 1.0/zd;
233	>	if (!n) {                       /* record first vertex & value */
234	>	if (zd > 10.0*thescene.cusize + 1000.)
235	>	zd = 10.0*thescene.cusize + 1000.;
236	>	VSUM(ap->p, ar.rorg, ar.rdir, zd);
237	>	copyscolor(ap->v, ar.rcol);
238	>	} else {                        /* else update recorded value */
239	>	sopscolor(hp->acol, -=, ap->v);
240	>	zd = 1.0/(double)(n+1);
241	>	scalescolor(ar.rcol, zd);
242	>	zd *= (double)n;
243	>	scalescolor(ap->v, zd);
244	>	saddscolor(ap->v, ar.rcol);
245	>	}
246	>	saddscolor(hp->acol, ap->v);    /* add to our sum */
247		return(1);
248		}
249
250
251	<	static AMBSAMP *
140	<	ambsample(                              /* initial ambient division sample */
141	<	AMBHEMI *hp,
142	<	int     i,
143	<	int     j
144	<	)
145	<	{
146	<	AMBSAMP *ap = &ambsam(hp,i,j);
147	<	RAY     ar;
148	<	/* generate hemispherical sample */
149	<	if (!getambsamp(&ar, hp, i, j, 0) || ar.rt <= FTINY) {
150	<	memset(ap, 0, sizeof(AMBSAMP));
151	<	return(NULL);
152	<	}
153	<	ap->d = 1.0/ar.rt;              /* limit vertex distance */
154	<	if (ar.rt > 10.0*thescene.cusize)
155	<	ar.rt = 10.0*thescene.cusize;
156	<	VSUM(ap->p, ar.rorg, ar.rdir, ar.rt);
157	<	copycolor(ap->v, ar.rcol);
158	<	return(ap);
159	<	}
160	<
161	<
162	<	/* Estimate errors based on ambient division differences */
251	>	/* Estimate variance based on ambient division differences */
252		static float *
253		getambdiffs(AMBHEMI *hp)
254		{
255	<	float   *earr = (float *)calloc(hp->ns*hp->ns, sizeof(float));
255	>	const double    normf = 1./(pbright(hp->acoef) + FTINY);
256	>	float   *earr = (float *)calloc(2*hp->ns*hp->ns, sizeof(float));
257		float   *ep;
258		AMBSAMP *ap;
259	<	double  b, d2;
259	>	double  b, b1, d2;
260		int     i, j;
261
262		if (earr == NULL)               /* out of memory? */
263		return(NULL);
264	<	/* compute squared neighbor diffs */
265	<	for (ap = hp->sa, ep = earr, i = 0; i < hp->ns; i++)
264	>	/* sum squared neighbor diffs */
265	>	ap = hp->sa;
266	>	ep = earr + hp->ns*hp->ns;      /* original estimates to scratch */
267	>	for (i = 0; i < hp->ns; i++)
268		for (j = 0; j < hp->ns; j++, ap++, ep++) {
269	<	b = bright(ap[0].v);
269	>	b = pbright(ap[0].v);
270		if (i) {                /* from above */
271	<	d2 = b - bright(ap[-hp->ns].v);
272	<	d2 *= d2;
271	>	b1 = pbright(ap[-hp->ns].v);
272	>	d2 = b - b1;
273	>	d2 *= d2*normf/(b + b1 + FTINY);
274		ep[0] += d2;
275		ep[-hp->ns] += d2;
276		}
277		if (!j) continue;
278		/* from behind */
279	<	d2 = b - bright(ap[-1].v);
280	<	d2 *= d2;
279	>	b1 = pbright(ap[-1].v);
280	>	d2 = b - b1;
281	>	d2 *= d2*normf/(b + b1 + FTINY);
282		ep[0] += d2;
283		ep[-1] += d2;
284		if (!i) continue;
285		/* diagonal */
286	<	d2 = b - bright(ap[-hp->ns-1].v);
287	<	d2 *= d2;
286	>	b1 = pbright(ap[-hp->ns-1].v);
287	>	d2 = b - b1;
288	>	d2 *= d2*normf/(b + b1 + FTINY);
289		ep[0] += d2;
290		ep[-hp->ns-1] += d2;
291		}
292		/* correct for number of neighbors */
293	<	earr[0] *= 8./3.;
294	<	earr[hp->ns-1] *= 8./3.;
295	<	earr[(hp->ns-1)*hp->ns] *= 8./3.;
296	<	earr[(hp->ns-1)*hp->ns + hp->ns-1] *= 8./3.;
293	>	ep = earr + hp->ns*hp->ns;
294	>	ep[0] *= 6./3.;
295	>	ep[hp->ns-1] *= 6./3.;
296	>	ep[(hp->ns-1)*hp->ns] *= 6./3.;
297	>	ep[(hp->ns-1)*hp->ns + hp->ns-1] *= 6./3.;
298		for (i = 1; i < hp->ns-1; i++) {
299	<	earr[i*hp->ns] *= 8./5.;
300	<	earr[i*hp->ns + hp->ns-1] *= 8./5.;
299	>	ep[i*hp->ns] *= 6./5.;
300	>	ep[i*hp->ns + hp->ns-1] *= 6./5.;
301		}
302		for (j = 1; j < hp->ns-1; j++) {
303	<	earr[j] *= 8./5.;
304	<	earr[(hp->ns-1)*hp->ns + j] *= 8./5.;
303	>	ep[j] *= 6./5.;
304	>	ep[(hp->ns-1)*hp->ns + j] *= 6./5.;
305		}
306	+	/* blur final map to reduce bias */
307	+	for (i = 0; i < hp->ns-1; i++) {
308	+	float  *ep2;
309	+	ep = earr + i*hp->ns;
310	+	ep2 = ep + hp->ns*hp->ns;
311	+	for (j = 0; j < hp->ns-1; j++, ep++, ep2++) {
312	+	ep[0] += .5*ep2[0] + .125*(ep2[1] + ep2[hp->ns]);
313	+	ep[1] += .125*ep2[0];
314	+	ep[hp->ns] += .125*ep2[0];
315	+	}
316	+	}
317		return(earr);
318		}
319
320
321		/* Perform super-sampling on hemisphere (introduces bias) */
322		static void
323	<	ambsupersamp(double acol[3], AMBHEMI *hp, int cnt)
323	>	ambsupersamp(AMBHEMI *hp, int cnt)
324		{
325		float   *earr = getambdiffs(hp);
326		double  e2rem = 0;
220	–	AMBSAMP *ap;
221	–	RAY     ar;
222	–	double  asum[3];
327		float   *ep;
328		int     i, j, n, nss;
329
#	Line 229 | Line 333 | ambsupersamp(double acol[3], AMBHEMI *hp, int cnt)
333		for (ep = earr + hp->ns*hp->ns; ep > earr; )
334		e2rem += *--ep;
335		ep = earr;                      /* perform super-sampling */
336	<	for (ap = hp->sa, i = 0; i < hp->ns; i++)
337	<	for (j = 0; j < hp->ns; j++, ap++) {
336	>	for (i = 0; i < hp->ns; i++)
337	>	for (j = 0; j < hp->ns; j++) {
338		if (e2rem <= FTINY)
339		goto done;      /* nothing left to do */
340		nss = *ep/e2rem*cnt + frandom();
341	<	asum[0] = asum[1] = asum[2] = 0.0;
342	<	for (n = 1; n <= nss; n++) {
343	<	if (!getambsamp(&ar, hp, i, j, n)) {
240	<	nss = n-1;
241	<	break;
242	<	}
243	<	addcolor(asum, ar.rcol);
244	<	}
245	<	if (nss) {              /* update returned ambient value */
246	<	const double    ssf = 1./(nss + 1.);
247	<	for (n = 3; n--; )
248	<	acol[n] += ssf*asum[n] +
249	<	(ssf - 1.)*colval(ap->v,n);
250	<	}
251	<	e2rem -= *ep++;         /* update remainders */
252	<	cnt -= nss;
341	>	for (n = 1; n <= nss && ambsample(hp,i,j,n); n++)
342	>	if (!--cnt) goto done;
343	>	e2rem -= *ep++;         /* update remainder */
344		}
345		done:
346		free(earr);
347		}
348
349
350	+	static AMBHEMI *
351	+	samp_hemi(                              /* sample indirect hemisphere */
352	+	SCOLOR  rcol,
353	+	RAY     *r,
354	+	double  wt
355	+	)
356	+	{
357	+	int     backside = (wt < 0);
358	+	AMBHEMI *hp;
359	+	double  d;
360	+	int     n, i, j;
361	+	/* insignificance check */
362	+	d = sintens(rcol);
363	+	if (d <= FTINY)
364	+	return(NULL);
365	+	/* set number of divisions */
366	+	if (backside) wt = -wt;
367	+	if (ambacc <= FTINY &&
368	+	wt > (d *= 0.8*r->rweight/(ambdiv*minweight + 1e-20)))
369	+	wt = d;                 /* avoid ray termination */
370	+	n = sqrt(ambdiv * wt) + 0.5;
371	+	i = 1 + (MINADIV-1)*(ambacc > FTINY);
372	+	if (n < i)                      /* use minimum number of samples? */
373	+	n = i;
374	+	/* allocate sampling array */
375	+	hp = (AMBHEMI *)malloc(sizeof(AMBHEMI) + sizeof(AMBSAMP)*(n*n - 1));
376	+	if (hp == NULL)
377	+	error(SYSTEM, "out of memory in samp_hemi");
378	+
379	+	if (backside) {
380	+	hp->atyp = TAMBIENT;
381	+	hp->onrm[0] = -r->ron[0];
382	+	hp->onrm[1] = -r->ron[1];
383	+	hp->onrm[2] = -r->ron[2];
384	+	} else {
385	+	hp->atyp = RAMBIENT;
386	+	VCOPY(hp->onrm, r->ron);
387	+	}
388	+	hp->rp = r;
389	+	hp->ns = n;
390	+	scolorblack(hp->acol);
391	+	memset(hp->sa, 0, sizeof(AMBSAMP)*n*n);
392	+	hp->sampOK = 0;
393	+	/* assign coefficient */
394	+	copyscolor(hp->acoef, rcol);
395	+	d = 1.0/(n*n);
396	+	scalescolor(hp->acoef, d);
397	+	/* make tangent plane axes */
398	+	if (!getperpendicular(hp->ux, hp->onrm, 1))
399	+	error(CONSISTENCY, "bad ray direction in samp_hemi");
400	+	VCROSS(hp->uy, hp->onrm, hp->ux);
401	+	/* sample divisions */
402	+	for (i = hp->ns; i--; )
403	+	for (j = hp->ns; j--; )
404	+	hp->sampOK += ambsample(hp, i, j, 0);
405	+	copyscolor(rcol, hp->acol);
406	+	if (!hp->sampOK) {              /* utter failure? */
407	+	free(hp);
408	+	return(NULL);
409	+	}
410	+	if (hp->sampOK < hp->ns*hp->ns) {
411	+	hp->sampOK *= -1;       /* soft failure */
412	+	return(hp);
413	+	}
414	+	if (hp->sampOK <= MINADIV*MINADIV)
415	+	return(hp);             /* don't bother super-sampling */
416	+	n = ambssamp*wt + 0.5;
417	+	if (n >= 4*hp->ns) {            /* perform super-sampling? */
418	+	ambsupersamp(hp, n);
419	+	copyscolor(rcol, hp->acol);
420	+	}
421	+	return(hp);                     /* all is well */
422	+	}
423	+
424	+
425		/* Return brightness of farthest ambient sample */
426		static double
427		back_ambval(AMBHEMI *hp, const int n1, const int n2, const int n3)
428		{
429		if (hp->sa[n1].d <= hp->sa[n2].d) {
430		if (hp->sa[n1].d <= hp->sa[n3].d)
431	<	return(colval(hp->sa[n1].v,CIEY));
432	<	return(colval(hp->sa[n3].v,CIEY));
431	>	return(hp->sa[n1].v[0]);
432	>	return(hp->sa[n3].v[0]);
433		}
434		if (hp->sa[n2].d <= hp->sa[n3].d)
435	<	return(colval(hp->sa[n2].v,CIEY));
436	<	return(colval(hp->sa[n3].v,CIEY));
435	>	return(hp->sa[n2].v[0]);
436	>	return(hp->sa[n3].v[0]);
437		}
438
439
#	Line 496 | Line 662 | ambHessian(                            /* anisotropic radii & pos. gradient */
662		for (j = 0; j < hp->ns-1; j++) {
663		comp_fftri(&fftr, hp, AI(hp,0,j), AI(hp,0,j+1));
664		if (hessrow != NULL)
665	<	comp_hessian(hessrow[j], &fftr, hp->rp->ron);
665	>	comp_hessian(hessrow[j], &fftr, hp->onrm);
666		if (gradrow != NULL)
667	<	comp_gradient(gradrow[j], &fftr, hp->rp->ron);
667	>	comp_gradient(gradrow[j], &fftr, hp->onrm);
668		}
669		/* sum each row of triangles */
670		for (i = 0; i < hp->ns-1; i++) {
#	Line 506 | Line 672 | ambHessian(                            /* anisotropic radii & pos. gradient */
672		FVECT       gradcol;
673		comp_fftri(&fftr, hp, AI(hp,i,0), AI(hp,i+1,0));
674		if (hessrow != NULL)
675	<	comp_hessian(hesscol, &fftr, hp->rp->ron);
675	>	comp_hessian(hesscol, &fftr, hp->onrm);
676		if (gradrow != NULL)
677	<	comp_gradient(gradcol, &fftr, hp->rp->ron);
677	>	comp_gradient(gradcol, &fftr, hp->onrm);
678		for (j = 0; j < hp->ns-1; j++) {
679		FVECT   hessdia[3];     /* compute triangle contributions */
680		FVECT   graddia;
#	Line 518 | Line 684 | ambHessian(                            /* anisotropic radii & pos. gradient */
684		/* diagonal (inner) edge */
685		comp_fftri(&fftr, hp, AI(hp,i,j+1), AI(hp,i+1,j));
686		if (hessrow != NULL) {
687	<	comp_hessian(hessdia, &fftr, hp->rp->ron);
687	>	comp_hessian(hessdia, &fftr, hp->onrm);
688		rev_hessian(hesscol);
689		add2hessian(hessian, hessrow[j], hessdia, hesscol, backg);
690		}
691		if (gradrow != NULL) {
692	<	comp_gradient(graddia, &fftr, hp->rp->ron);
692	>	comp_gradient(graddia, &fftr, hp->onrm);
693		rev_gradient(gradcol);
694		add2gradient(gradient, gradrow[j], graddia, gradcol, backg);
695		}
696		/* initialize edge in next row */
697		comp_fftri(&fftr, hp, AI(hp,i+1,j+1), AI(hp,i+1,j));
698		if (hessrow != NULL)
699	<	comp_hessian(hessrow[j], &fftr, hp->rp->ron);
699	>	comp_hessian(hessrow[j], &fftr, hp->onrm);
700		if (gradrow != NULL)
701	<	comp_gradient(gradrow[j], &fftr, hp->rp->ron);
701	>	comp_gradient(gradrow[j], &fftr, hp->onrm);
702		/* new column edge & paired triangle */
703		backg = back_ambval(hp, AI(hp,i+1,j+1),
704		AI(hp,i+1,j), AI(hp,i,j+1));
705		comp_fftri(&fftr, hp, AI(hp,i,j+1), AI(hp,i+1,j+1));
706		if (hessrow != NULL) {
707	<	comp_hessian(hesscol, &fftr, hp->rp->ron);
707	>	comp_hessian(hesscol, &fftr, hp->onrm);
708		rev_hessian(hessdia);
709		add2hessian(hessian, hessrow[j], hessdia, hesscol, backg);
710		if (i < hp->ns-2)
711		rev_hessian(hessrow[j]);
712		}
713		if (gradrow != NULL) {
714	<	comp_gradient(gradcol, &fftr, hp->rp->ron);
714	>	comp_gradient(gradcol, &fftr, hp->onrm);
715		rev_gradient(graddia);
716		add2gradient(gradient, gradrow[j], graddia, gradcol, backg);
717		if (i < hp->ns-2)
#	Line 581 | Line 747 | ambdirgrad(AMBHEMI *hp, FVECT uv[2], float dg[2])
747		/* use vector for azimuth + 90deg */
748		VSUB(vd, ap->p, hp->rp->rop);
749		/* brightness over cosine factor */
750	<	gfact = colval(ap->v,CIEY) / DOT(hp->rp->ron, vd);
750	>	gfact = ap->v[0] / DOT(hp->onrm, vd);
751		/* sine = proj_radius/vd_length */
752		dgsum[0] -= DOT(uv[1], vd) * gfact;
753		dgsum[1] += DOT(uv[0], vd) * gfact;
#	Line 596 | Line 762 | static uint32
762		ambcorral(AMBHEMI *hp, FVECT uv[2], const double r0, const double r1)
763		{
764		const double    max_d = 1.0/(minarad*ambacc + 0.001);
765	<	const double    ang_res = 0.5*PI/(hp->ns-1);
766	<	const double    ang_step = ang_res/((int)(16/PI*ang_res) + (1+FTINY));
765	>	const double    ang_res = 0.5*PI/hp->ns;
766	>	const double    ang_step = ang_res/((int)(16/PI*ang_res) + 1.01);
767		double          avg_d = 0;
768		uint32          flgs = 0;
769		FVECT           vec;
#	Line 605 | Line 771 | ambcorral(AMBHEMI *hp, FVECT uv[2], const double r0, c
771		double          ang, a1;
772		int             i, j;
773		/* don't bother for a few samples */
774	<	if (hp->ns < 12)
774	>	if (hp->ns < 8)
775		return(0);
776		/* check distances overhead */
777		for (i = hp->ns*3/4; i-- > hp->ns>>2; )
#	Line 623 | Line 789 | ambcorral(AMBHEMI *hp, FVECT uv[2], const double r0, c
789		if ((ap->d <= FTINY) | (ap->d >= max_d))
790		continue;       /* too far or too near */
791		VSUB(vec, ap->p, hp->rp->rop);
792	<	u = DOT(vec, uv[0]) * ap->d;
793	<	v = DOT(vec, uv[1]) * ap->d;
794	<	if ((r0*r0*u*u + r1*r1*v*v) * ap->d*ap->d <= 1.0)
792	>	u = DOT(vec, uv[0]);
793	>	v = DOT(vec, uv[1]);
794	>	if ((r0*r0*u*u + r1*r1*v*v) * ap->d*ap->d <= u*u + v*v)
795		continue;       /* occluder outside ellipse */
796		ang = atan2a(v, u);     /* else set direction flags */
797	<	for (a1 = ang-.5*ang_res; a1 <= ang+.5*ang_res; a1 += ang_step)
797	>	for (a1 = ang-ang_res; a1 <= ang+ang_res; a1 += ang_step)
798		flgs |= 1L<<(int)(16/PI*(a1 + 2.*PI*(a1 < 0)));
799		}
634	–	/* add low-angle incident (< 20deg) */
635	–	if (fabs(hp->rp->rod) <= 0.342) {
636	–	u = -DOT(hp->rp->rdir, uv[0]);
637	–	v = -DOT(hp->rp->rdir, uv[1]);
638	–	if ((r0*r0*u*u + r1*r1*v*v) > hp->rp->rot*hp->rp->rot) {
639	–	ang = atan2a(v, u);
640	–	ang += 2.*PI*(ang < 0);
641	–	ang *= 16/PI;
642	–	if ((ang < .5) | (ang >= 31.5))
643	–	flgs |= 0x80000001;
644	–	else
645	–	flgs |= 3L<<(int)(ang-.5);
646	–	}
647	–	}
800		return(flgs);
801		}
802
803
804		int
805		doambient(                              /* compute ambient component */
806	<	COLOR   rcol,                   /* input/output color */
806	>	SCOLOR  rcol,                   /* input/output color */
807		RAY     *r,
808	<	double  wt,
808	>	double  wt,                     /* negative for back side */
809		FVECT   uv[2],                  /* returned (optional) */
810		float   ra[2],                  /* returned (optional) */
811		float   pg[2],                  /* returned (optional) */
#	Line 661 | Line 813 | doambient(                             /* compute ambient component */
813		uint32  *crlp                   /* returned (optional) */
814		)
815		{
816	<	AMBHEMI *hp = inithemi(rcol, r, wt);
665	<	int     cnt;
816	>	AMBHEMI *hp = samp_hemi(rcol, r, wt);
817		FVECT   my_uv[2];
818	<	double  d, K, acol[3];
818	>	double  d, K;
819		AMBSAMP *ap;
820	<	int     i, j;
821	<	/* check/initialize */
671	<	if (hp == NULL)
672	<	return(0);
820	>	int     i;
821	>	/* clear return values */
822		if (uv != NULL)
823		memset(uv, 0, sizeof(FVECT)*2);
824		if (ra != NULL)
#	Line 680 | Line 829 | doambient(                             /* compute ambient component */
829		dg[0] = dg[1] = 0.0;
830		if (crlp != NULL)
831		*crlp = 0;
832	<	/* sample the hemisphere */
833	<	acol[0] = acol[1] = acol[2] = 0.0;
834	<	cnt = 0;
835	<	for (i = hp->ns; i--; )
836	<	for (j = hp->ns; j--; )
837	<	if ((ap = ambsample(hp, i, j)) != NULL) {
838	<	addcolor(acol, ap->v);
690	<	++cnt;
691	<	}
692	<	if (!cnt) {
693	<	setcolor(rcol, 0.0, 0.0, 0.0);
694	<	free(hp);
695	<	return(0);              /* no valid samples */
832	>	if (hp == NULL)                 /* sampling falure? */
833	>	return(0);
834	>
835	>	if ((ra == NULL) & (pg == NULL) & (dg == NULL) ||
836	>	(hp->sampOK < 0) | (hp->ns < MINADIV)) {
837	>	free(hp);               /* Hessian not requested/possible */
838	>	return(-1);             /* value-only return value */
839		}
840	<	if (cnt < hp->ns*hp->ns) {      /* incomplete sampling? */
841	<	copycolor(rcol, acol);
699	<	free(hp);
700	<	return(-1);             /* return value w/o Hessian */
701	<	}
702	<	cnt = ambssamp*wt + 0.5;        /* perform super-sampling? */
703	<	if (cnt > 8)
704	<	ambsupersamp(acol, hp, cnt);
705	<	copycolor(rcol, acol);          /* final indirect irradiance/PI */
706	<	if ((ra == NULL) & (pg == NULL) & (dg == NULL)) {
707	<	free(hp);
708	<	return(-1);             /* no radius or gradient calc. */
709	<	}
710	<	if ((d = bright(acol)) > FTINY) {       /* normalize Y values */
711	<	d = 0.99*(hp->ns*hp->ns)/d;
840	>	if ((d = scolor_mean(rcol)) > FTINY) {
841	>	d = 0.99*(hp->ns*hp->ns)/d;     /* normalize avg. values */
842		K = 0.01;
843		} else {                        /* or fall back on geometric Hessian */
844		K = 1.0;
#	Line 716 | Line 846 | doambient(                             /* compute ambient component */
846		dg = NULL;
847		crlp = NULL;
848		}
849	<	ap = hp->sa;                    /* relative Y channel from here on... */
849	>	ap = hp->sa;                    /* single channel from here on... */
850		for (i = hp->ns*hp->ns; i--; ap++)
851	<	colval(ap->v,CIEY) = bright(ap->v)*d + K;
851	>	ap->v[0] = scolor_mean(ap->v)*d + K;
852
853		if (uv == NULL)                 /* make sure we have axis pointers */
854		uv = my_uv;
#	Line 742 | Line 872 | doambient(                             /* compute ambient component */
872		if (ra[1] < minarad)
873		ra[1] = minarad;
874		}
875	<	ra[0] *= d = 1.0/sqrt(sqrt(wt));
875	>	ra[0] *= d = 1.0/sqrt(fabs(wt));
876		if ((ra[1] *= d) > 2.0*ra[0])
877		ra[1] = 2.0*ra[0];
878		if (ra[1] > maxarad) {
#	Line 751 | Line 881 | doambient(                             /* compute ambient component */
881		ra[0] = maxarad;
882		}
883		/* flag encroached directions */
884	<	if ((wt >= 0.89*AVGREFL) & (crlp != NULL))
884	>	if (crlp != NULL)       /* XXX doesn't update with changes to ambacc */
885		*crlp = ambcorral(hp, uv, ra[0]*ambacc, ra[1]*ambacc);
886		if (pg != NULL) {       /* cap gradient if necessary */
887		d = pg[0]*pg[0]*ra[0]*ra[0] + pg[1]*pg[1]*ra[1]*ra[1];
#	Line 765 | Line 895 | doambient(                             /* compute ambient component */
895		free(hp);                       /* clean up and return */
896		return(1);
897		}
768	–
769	–
770	–	#else /* ! NEWAMB */
771	–
772	–
773	–	void
774	–	inithemi(                       /* initialize sampling hemisphere */
775	–	AMBHEMI  *hp,
776	–	COLOR ac,
777	–	RAY  *r,
778	–	double  wt
779	–	)
780	–	{
781	–	double  d;
782	–	int  i;
783	–	/* set number of divisions */
784	–	if (ambacc <= FTINY &&
785	–	wt > (d = 0.8*intens(ac)*r->rweight/(ambdiv*minweight)))
786	–	wt = d;                 /* avoid ray termination */
787	–	hp->nt = sqrt(ambdiv * wt / PI) + 0.5;
788	–	i = ambacc > FTINY ? 3 : 1;     /* minimum number of samples */
789	–	if (hp->nt < i)
790	–	hp->nt = i;
791	–	hp->np = PI * hp->nt + 0.5;
792	–	/* set number of super-samples */
793	–	hp->ns = ambssamp * wt + 0.5;
794	–	/* assign coefficient */
795	–	copycolor(hp->acoef, ac);
796	–	d = 1.0/(hp->nt*hp->np);
797	–	scalecolor(hp->acoef, d);
798	–	/* make axes */
799	–	VCOPY(hp->uz, r->ron);
800	–	hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
801	–	for (i = 0; i < 3; i++)
802	–	if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6)
803	–	break;
804	–	if (i >= 3)
805	–	error(CONSISTENCY, "bad ray direction in inithemi");
806	–	hp->uy[i] = 1.0;
807	–	fcross(hp->ux, hp->uy, hp->uz);
808	–	normalize(hp->ux);
809	–	fcross(hp->uy, hp->uz, hp->ux);
810	–	}
811	–
812	–
813	–	int
814	–	divsample(                              /* sample a division */
815	–	AMBSAMP  *dp,
816	–	AMBHEMI  *h,
817	–	RAY  *r
818	–	)
819	–	{
820	–	RAY  ar;
821	–	int  hlist[3];
822	–	double  spt[2];
823	–	double  xd, yd, zd;
824	–	double  b2;
825	–	double  phi;
826	–	int  i;
827	–	/* ambient coefficient for weight */
828	–	if (ambacc > FTINY)
829	–	setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
830	–	else
831	–	copycolor(ar.rcoef, h->acoef);
832	–	if (rayorigin(&ar, AMBIENT, r, ar.rcoef) < 0)
833	–	return(-1);
834	–	if (ambacc > FTINY) {
835	–	multcolor(ar.rcoef, h->acoef);
836	–	scalecolor(ar.rcoef, 1./AVGREFL);
837	–	}
838	–	hlist[0] = r->rno;
839	–	hlist[1] = dp->t;
840	–	hlist[2] = dp->p;
841	–	multisamp(spt, 2, urand(ilhash(hlist,3)+dp->n));
842	–	zd = sqrt((dp->t + spt[0])/h->nt);
843	–	phi = 2.0*PI * (dp->p + spt[1])/h->np;
844	–	xd = tcos(phi) * zd;
845	–	yd = tsin(phi) * zd;
846	–	zd = sqrt(1.0 - zd*zd);
847	–	for (i = 0; i < 3; i++)
848	–	ar.rdir[i] =    xd*h->ux[i] +
849	–	yd*h->uy[i] +
850	–	zd*h->uz[i];
851	–	checknorm(ar.rdir);
852	–	dimlist[ndims++] = dp->t*h->np + dp->p + 90171;
853	–	rayvalue(&ar);
854	–	ndims--;
855	–	multcolor(ar.rcol, ar.rcoef);   /* apply coefficient */
856	–	addcolor(dp->v, ar.rcol);
857	–	/* use rt to improve gradient calc */
858	–	if (ar.rt > FTINY && ar.rt < FHUGE)
859	–	dp->r += 1.0/ar.rt;
860	–	/* (re)initialize error */
861	–	if (dp->n++) {
862	–	b2 = bright(dp->v)/dp->n - bright(ar.rcol);
863	–	b2 = b2*b2 + dp->k*((dp->n-1)*(dp->n-1));
864	–	dp->k = b2/(dp->n*dp->n);
865	–	} else
866	–	dp->k = 0.0;
867	–	return(0);
868	–	}
869	–
870	–
871	–	static int
872	–	ambcmp(                                 /* decreasing order */
873	–	const void *p1,
874	–	const void *p2
875	–	)
876	–	{
877	–	const AMBSAMP   *d1 = (const AMBSAMP *)p1;
878	–	const AMBSAMP   *d2 = (const AMBSAMP *)p2;
879	–
880	–	if (d1->k < d2->k)
881	–	return(1);
882	–	if (d1->k > d2->k)
883	–	return(-1);
884	–	return(0);
885	–	}
886	–
887	–
888	–	static int
889	–	ambnorm(                                /* standard order */
890	–	const void *p1,
891	–	const void *p2
892	–	)
893	–	{
894	–	const AMBSAMP   *d1 = (const AMBSAMP *)p1;
895	–	const AMBSAMP   *d2 = (const AMBSAMP *)p2;
896	–	int     c;
897	–
898	–	if ( (c = d1->t - d2->t) )
899	–	return(c);
900	–	return(d1->p - d2->p);
901	–	}
902	–
903	–
904	–	double
905	–	doambient(                              /* compute ambient component */
906	–	COLOR  rcol,
907	–	RAY  *r,
908	–	double  wt,
909	–	FVECT  pg,
910	–	FVECT  dg
911	–	)
912	–	{
913	–	double  b, d=0;
914	–	AMBHEMI  hemi;
915	–	AMBSAMP  *div;
916	–	AMBSAMP  dnew;
917	–	double  acol[3];
918	–	AMBSAMP  *dp;
919	–	double  arad;
920	–	int  divcnt;
921	–	int  i, j;
922	–	/* initialize hemisphere */
923	–	inithemi(&hemi, rcol, r, wt);
924	–	divcnt = hemi.nt * hemi.np;
925	–	/* initialize */
926	–	if (pg != NULL)
927	–	pg[0] = pg[1] = pg[2] = 0.0;
928	–	if (dg != NULL)
929	–	dg[0] = dg[1] = dg[2] = 0.0;
930	–	setcolor(rcol, 0.0, 0.0, 0.0);
931	–	if (divcnt == 0)
932	–	return(0.0);
933	–	/* allocate super-samples */
934	–	if (hemi.ns > 0 || pg != NULL || dg != NULL) {
935	–	div = (AMBSAMP *)malloc(divcnt*sizeof(AMBSAMP));
936	–	if (div == NULL)
937	–	error(SYSTEM, "out of memory in doambient");
938	–	} else
939	–	div = NULL;
940	–	/* sample the divisions */
941	–	arad = 0.0;
942	–	acol[0] = acol[1] = acol[2] = 0.0;
943	–	if ((dp = div) == NULL)
944	–	dp = &dnew;
945	–	divcnt = 0;
946	–	for (i = 0; i < hemi.nt; i++)
947	–	for (j = 0; j < hemi.np; j++) {
948	–	dp->t = i; dp->p = j;
949	–	setcolor(dp->v, 0.0, 0.0, 0.0);
950	–	dp->r = 0.0;
951	–	dp->n = 0;
952	–	if (divsample(dp, &hemi, r) < 0) {
953	–	if (div != NULL)
954	–	dp++;
955	–	continue;
956	–	}
957	–	arad += dp->r;
958	–	divcnt++;
959	–	if (div != NULL)
960	–	dp++;
961	–	else
962	–	addcolor(acol, dp->v);
963	–	}
964	–	if (!divcnt) {
965	–	if (div != NULL)
966	–	free((void *)div);
967	–	return(0.0);            /* no samples taken */
968	–	}
969	–	if (divcnt < hemi.nt*hemi.np) {
970	–	pg = dg = NULL;         /* incomplete sampling */
971	–	hemi.ns = 0;
972	–	} else if (arad > FTINY && divcnt/arad < minarad) {
973	–	hemi.ns = 0;            /* close enough */
974	–	} else if (hemi.ns > 0) {       /* else perform super-sampling? */
975	–	comperrs(div, &hemi);                   /* compute errors */
976	–	qsort(div, divcnt, sizeof(AMBSAMP), ambcmp);    /* sort divs */
977	–	/* super-sample */
978	–	for (i = hemi.ns; i > 0; i--) {
979	–	dnew = *div;
980	–	if (divsample(&dnew, &hemi, r) < 0) {
981	–	dp++;
982	–	continue;
983	–	}
984	–	dp = div;               /* reinsert */
985	–	j = divcnt < i ? divcnt : i;
986	–	while (--j > 0 && dnew.k < dp[1].k) {
987	–	*dp = *(dp+1);
988	–	dp++;
989	–	}
990	–	*dp = dnew;
991	–	}
992	–	if (pg != NULL || dg != NULL)   /* restore order */
993	–	qsort(div, divcnt, sizeof(AMBSAMP), ambnorm);
994	–	}
995	–	/* compute returned values */
996	–	if (div != NULL) {
997	–	arad = 0.0;             /* note: divcnt may be < nt*np */
998	–	for (i = hemi.nt*hemi.np, dp = div; i-- > 0; dp++) {
999	–	arad += dp->r;
1000	–	if (dp->n > 1) {
1001	–	b = 1.0/dp->n;
1002	–	scalecolor(dp->v, b);
1003	–	dp->r *= b;
1004	–	dp->n = 1;
1005	–	}
1006	–	addcolor(acol, dp->v);
1007	–	}
1008	–	b = bright(acol);
1009	–	if (b > FTINY) {
1010	–	b = 1.0/b;      /* compute & normalize gradient(s) */
1011	–	if (pg != NULL) {
1012	–	posgradient(pg, div, &hemi);
1013	–	for (i = 0; i < 3; i++)
1014	–	pg[i] *= b;
1015	–	}
1016	–	if (dg != NULL) {
1017	–	dirgradient(dg, div, &hemi);
1018	–	for (i = 0; i < 3; i++)
1019	–	dg[i] *= b;
1020	–	}
1021	–	}
1022	–	free((void *)div);
1023	–	}
1024	–	copycolor(rcol, acol);
1025	–	if (arad <= FTINY)
1026	–	arad = maxarad;
1027	–	else
1028	–	arad = (divcnt+hemi.ns)/arad;
1029	–	if (pg != NULL) {               /* reduce radius if gradient large */
1030	–	d = DOT(pg,pg);
1031	–	if (d*arad*arad > 1.0)
1032	–	arad = 1.0/sqrt(d);
1033	–	}
1034	–	if (arad < minarad) {
1035	–	arad = minarad;
1036	–	if (pg != NULL && d*arad*arad > 1.0) {  /* cap gradient */
1037	–	d = 1.0/arad/sqrt(d);
1038	–	for (i = 0; i < 3; i++)
1039	–	pg[i] *= d;
1040	–	}
1041	–	}
1042	–	if ((arad /= sqrt(wt)) > maxarad)
1043	–	arad = maxarad;
1044	–	return(arad);
1045	–	}
1046	–
1047	–
1048	–	void
1049	–	comperrs(                       /* compute initial error estimates */
1050	–	AMBSAMP  *da,   /* assumes standard ordering */
1051	–	AMBHEMI  *hp
1052	–	)
1053	–	{
1054	–	double  b, b2;
1055	–	int  i, j;
1056	–	AMBSAMP  *dp;
1057	–	/* sum differences from neighbors */
1058	–	dp = da;
1059	–	for (i = 0; i < hp->nt; i++)
1060	–	for (j = 0; j < hp->np; j++) {
1061	–	#ifdef  DEBUG
1062	–	if (dp->t != i || dp->p != j)
1063	–	error(CONSISTENCY,
1064	–	"division order in comperrs");
1065	–	#endif
1066	–	b = bright(dp[0].v);
1067	–	if (i > 0) {            /* from above */
1068	–	b2 = bright(dp[-hp->np].v) - b;
1069	–	b2 *= b2 * 0.25;
1070	–	dp[0].k += b2;
1071	–	dp[-hp->np].k += b2;
1072	–	}
1073	–	if (j > 0) {            /* from behind */
1074	–	b2 = bright(dp[-1].v) - b;
1075	–	b2 *= b2 * 0.25;
1076	–	dp[0].k += b2;
1077	–	dp[-1].k += b2;
1078	–	} else {                /* around */
1079	–	b2 = bright(dp[hp->np-1].v) - b;
1080	–	b2 *= b2 * 0.25;
1081	–	dp[0].k += b2;
1082	–	dp[hp->np-1].k += b2;
1083	–	}
1084	–	dp++;
1085	–	}
1086	–	/* divide by number of neighbors */
1087	–	dp = da;
1088	–	for (j = 0; j < hp->np; j++)            /* top row */
1089	–	(dp++)->k *= 1.0/3.0;
1090	–	if (hp->nt < 2)
1091	–	return;
1092	–	for (i = 1; i < hp->nt-1; i++)          /* central region */
1093	–	for (j = 0; j < hp->np; j++)
1094	–	(dp++)->k *= 0.25;
1095	–	for (j = 0; j < hp->np; j++)            /* bottom row */
1096	–	(dp++)->k *= 1.0/3.0;
1097	–	}
1098	–
1099	–
1100	–	void
1101	–	posgradient(                                    /* compute position gradient */
1102	–	FVECT  gv,
1103	–	AMBSAMP  *da,                   /* assumes standard ordering */
1104	–	AMBHEMI  *hp
1105	–	)
1106	–	{
1107	–	int  i, j;
1108	–	double  nextsine, lastsine, b, d;
1109	–	double  mag0, mag1;
1110	–	double  phi, cosp, sinp, xd, yd;
1111	–	AMBSAMP  *dp;
1112	–
1113	–	xd = yd = 0.0;
1114	–	for (j = 0; j < hp->np; j++) {
1115	–	dp = da + j;
1116	–	mag0 = mag1 = 0.0;
1117	–	lastsine = 0.0;
1118	–	for (i = 0; i < hp->nt; i++) {
1119	–	#ifdef  DEBUG
1120	–	if (dp->t != i || dp->p != j)
1121	–	error(CONSISTENCY,
1122	–	"division order in posgradient");
1123	–	#endif
1124	–	b = bright(dp->v);
1125	–	if (i > 0) {
1126	–	d = dp[-hp->np].r;
1127	–	if (dp[0].r > d) d = dp[0].r;
1128	–	/* sin(t)*cos(t)^2 */
1129	–	d *= lastsine * (1.0 - (double)i/hp->nt);
1130	–	mag0 += d*(b - bright(dp[-hp->np].v));
1131	–	}
1132	–	nextsine = sqrt((double)(i+1)/hp->nt);
1133	–	if (j > 0) {
1134	–	d = dp[-1].r;
1135	–	if (dp[0].r > d) d = dp[0].r;
1136	–	mag1 += d * (nextsine - lastsine) *
1137	–	(b - bright(dp[-1].v));
1138	–	} else {
1139	–	d = dp[hp->np-1].r;
1140	–	if (dp[0].r > d) d = dp[0].r;
1141	–	mag1 += d * (nextsine - lastsine) *
1142	–	(b - bright(dp[hp->np-1].v));
1143	–	}
1144	–	dp += hp->np;
1145	–	lastsine = nextsine;
1146	–	}
1147	–	mag0 *= 2.0*PI / hp->np;
1148	–	phi = 2.0*PI * (double)j/hp->np;
1149	–	cosp = tcos(phi); sinp = tsin(phi);
1150	–	xd += mag0*cosp - mag1*sinp;
1151	–	yd += mag0*sinp + mag1*cosp;
1152	–	}
1153	–	for (i = 0; i < 3; i++)
1154	–	gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])*(hp->nt*hp->np)/PI;
1155	–	}
1156	–
1157	–
1158	–	void
1159	–	dirgradient(                                    /* compute direction gradient */
1160	–	FVECT  gv,
1161	–	AMBSAMP  *da,                   /* assumes standard ordering */
1162	–	AMBHEMI  *hp
1163	–	)
1164	–	{
1165	–	int  i, j;
1166	–	double  mag;
1167	–	double  phi, xd, yd;
1168	–	AMBSAMP  *dp;
1169	–
1170	–	xd = yd = 0.0;
1171	–	for (j = 0; j < hp->np; j++) {
1172	–	dp = da + j;
1173	–	mag = 0.0;
1174	–	for (i = 0; i < hp->nt; i++) {
1175	–	#ifdef  DEBUG
1176	–	if (dp->t != i || dp->p != j)
1177	–	error(CONSISTENCY,
1178	–	"division order in dirgradient");
1179	–	#endif
1180	–	/* tan(t) */
1181	–	mag += bright(dp->v)/sqrt(hp->nt/(i+.5) - 1.0);
1182	–	dp += hp->np;
1183	–	}
1184	–	phi = 2.0*PI * (j+.5)/hp->np + PI/2.0;
1185	–	xd += mag * tcos(phi);
1186	–	yd += mag * tsin(phi);
1187	–	}
1188	–	for (i = 0; i < 3; i++)
1189	–	gv[i] = xd*hp->ux[i] + yd*hp->uy[i];
1190	–	}
1191	–
1192	–	#endif  /* ! NEWAMB */

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