1 |
#ifndef lint |
2 |
static const char RCSid[] = "$Id: ambcomp.c,v 2.13 2005/04/13 23:00:59 greg Exp $"; |
3 |
#endif |
4 |
/* |
5 |
* Routines to compute "ambient" values using Monte Carlo |
6 |
* |
7 |
* Declarations of external symbols in ambient.h |
8 |
*/ |
9 |
|
10 |
#include "copyright.h" |
11 |
|
12 |
#include "ray.h" |
13 |
|
14 |
#include "ambient.h" |
15 |
|
16 |
#include "random.h" |
17 |
|
18 |
|
19 |
int |
20 |
inithemi( /* initialize sampling hemisphere */ |
21 |
register AMBHEMI *hp, |
22 |
RAY *r, |
23 |
COLOR ac, |
24 |
double wt |
25 |
) |
26 |
{ |
27 |
int ns; |
28 |
double d; |
29 |
register int i; |
30 |
/* set number of divisions */ |
31 |
hp->nt = sqrt(ambdiv * wt / PI) + 0.5; |
32 |
i = ambacc > FTINY ? 3 : 1; /* minimum number of samples */ |
33 |
if (hp->nt < i) |
34 |
hp->nt = i; |
35 |
hp->np = PI * hp->nt + 0.5; |
36 |
/* set number of super-samples */ |
37 |
ns = ambssamp * wt + 0.5; |
38 |
/* assign coefficient */ |
39 |
d = 1.0/(hp->nt*hp->np + ns); /* XXX weight not uniform if ns > 0 */ |
40 |
copycolor(hp->acoef, ac); |
41 |
scalecolor(hp->acoef, d); |
42 |
/* make axes */ |
43 |
VCOPY(hp->uz, r->ron); |
44 |
hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0; |
45 |
for (i = 0; i < 3; i++) |
46 |
if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6) |
47 |
break; |
48 |
if (i >= 3) |
49 |
error(CONSISTENCY, "bad ray direction in inithemi"); |
50 |
hp->uy[i] = 1.0; |
51 |
fcross(hp->ux, hp->uy, hp->uz); |
52 |
normalize(hp->ux); |
53 |
fcross(hp->uy, hp->uz, hp->ux); |
54 |
return(ns); |
55 |
} |
56 |
|
57 |
|
58 |
int |
59 |
divsample( /* sample a division */ |
60 |
register AMBSAMP *dp, |
61 |
AMBHEMI *h, |
62 |
RAY *r |
63 |
) |
64 |
{ |
65 |
RAY ar; |
66 |
int hlist[3]; |
67 |
double spt[2]; |
68 |
double xd, yd, zd; |
69 |
double b2; |
70 |
double phi; |
71 |
register int i; |
72 |
/* assign coefficient */ |
73 |
if (ambacc <= FTINY) /* no storage, so report accurately */ |
74 |
copycolor(ar.rcoef, h->acoef); |
75 |
else /* else lie for sake of cache */ |
76 |
setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL); |
77 |
if (rayorigin(&ar, AMBIENT, r, ar.rcoef) < 0) |
78 |
return(-1); |
79 |
copycolor(ar.rcoef, h->acoef); /* correct coefficient rtrace output */ |
80 |
hlist[0] = r->rno; |
81 |
hlist[1] = dp->t; |
82 |
hlist[2] = dp->p; |
83 |
multisamp(spt, 2, urand(ilhash(hlist,3)+dp->n)); |
84 |
zd = sqrt((dp->t + spt[0])/h->nt); |
85 |
phi = 2.0*PI * (dp->p + spt[1])/h->np; |
86 |
xd = tcos(phi) * zd; |
87 |
yd = tsin(phi) * zd; |
88 |
zd = sqrt(1.0 - zd*zd); |
89 |
for (i = 0; i < 3; i++) |
90 |
ar.rdir[i] = xd*h->ux[i] + |
91 |
yd*h->uy[i] + |
92 |
zd*h->uz[i]; |
93 |
dimlist[ndims++] = dp->t*h->np + dp->p + 90171; |
94 |
rayvalue(&ar); |
95 |
ndims--; |
96 |
addcolor(dp->v, ar.rcol); |
97 |
/* use rt to improve gradient calc */ |
98 |
if (ar.rt > FTINY && ar.rt < FHUGE) |
99 |
dp->r += 1.0/ar.rt; |
100 |
/* (re)initialize error */ |
101 |
if (dp->n++) { |
102 |
b2 = bright(dp->v)/dp->n - bright(ar.rcol); |
103 |
b2 = b2*b2 + dp->k*((dp->n-1)*(dp->n-1)); |
104 |
dp->k = b2/(dp->n*dp->n); |
105 |
} else |
106 |
dp->k = 0.0; |
107 |
return(0); |
108 |
} |
109 |
|
110 |
|
111 |
static int |
112 |
ambcmp( /* decreasing order */ |
113 |
const void *p1, |
114 |
const void *p2 |
115 |
) |
116 |
{ |
117 |
const AMBSAMP *d1 = (const AMBSAMP *)p1; |
118 |
const AMBSAMP *d2 = (const AMBSAMP *)p2; |
119 |
|
120 |
if (d1->k < d2->k) |
121 |
return(1); |
122 |
if (d1->k > d2->k) |
123 |
return(-1); |
124 |
return(0); |
125 |
} |
126 |
|
127 |
|
128 |
static int |
129 |
ambnorm( /* standard order */ |
130 |
const void *p1, |
131 |
const void *p2 |
132 |
) |
133 |
{ |
134 |
const AMBSAMP *d1 = (const AMBSAMP *)p1; |
135 |
const AMBSAMP *d2 = (const AMBSAMP *)p2; |
136 |
register int c; |
137 |
|
138 |
if ( (c = d1->t - d2->t) ) |
139 |
return(c); |
140 |
return(d1->p - d2->p); |
141 |
} |
142 |
|
143 |
|
144 |
double |
145 |
doambient( /* compute ambient component */ |
146 |
COLOR acol, |
147 |
RAY *r, |
148 |
COLOR ac, |
149 |
double wt, |
150 |
FVECT pg, |
151 |
FVECT dg |
152 |
) |
153 |
{ |
154 |
double b, d; |
155 |
AMBHEMI hemi; |
156 |
AMBSAMP *div; |
157 |
AMBSAMP dnew; |
158 |
register AMBSAMP *dp; |
159 |
double arad; |
160 |
int ndivs, ns; |
161 |
register int i, j; |
162 |
/* initialize color */ |
163 |
setcolor(acol, 0.0, 0.0, 0.0); |
164 |
/* initialize hemisphere */ |
165 |
ns = inithemi(&hemi, r, ac, wt); |
166 |
ndivs = hemi.nt * hemi.np; |
167 |
if (ndivs == 0) |
168 |
return(0.0); |
169 |
/* allocate super-samples */ |
170 |
if (ns > 0 || pg != NULL || dg != NULL) { |
171 |
div = (AMBSAMP *)malloc(ndivs*sizeof(AMBSAMP)); |
172 |
if (div == NULL) |
173 |
error(SYSTEM, "out of memory in doambient"); |
174 |
} else |
175 |
div = NULL; |
176 |
/* sample the divisions */ |
177 |
arad = 0.0; |
178 |
if ((dp = div) == NULL) |
179 |
dp = &dnew; |
180 |
for (i = 0; i < hemi.nt; i++) |
181 |
for (j = 0; j < hemi.np; j++) { |
182 |
dp->t = i; dp->p = j; |
183 |
setcolor(dp->v, 0.0, 0.0, 0.0); |
184 |
dp->r = 0.0; |
185 |
dp->n = 0; |
186 |
if (divsample(dp, &hemi, r) < 0) |
187 |
goto oopsy; |
188 |
arad += dp->r; |
189 |
if (div != NULL) |
190 |
dp++; |
191 |
else |
192 |
addcolor(acol, dp->v); |
193 |
} |
194 |
if (ns > 0 && arad > FTINY && ndivs/arad < minarad) |
195 |
ns = 0; /* close enough */ |
196 |
else if (ns > 0) { /* else perform super-sampling */ |
197 |
comperrs(div, &hemi); /* compute errors */ |
198 |
qsort(div, ndivs, sizeof(AMBSAMP), ambcmp); /* sort divs */ |
199 |
/* super-sample */ |
200 |
for (i = ns; i > 0; i--) { |
201 |
dnew = *div; |
202 |
if (divsample(&dnew, &hemi, r) < 0) |
203 |
goto oopsy; |
204 |
/* reinsert */ |
205 |
dp = div; |
206 |
j = ndivs < i ? ndivs : i; |
207 |
while (--j > 0 && dnew.k < dp[1].k) { |
208 |
*dp = *(dp+1); |
209 |
dp++; |
210 |
} |
211 |
*dp = dnew; |
212 |
} |
213 |
if (pg != NULL || dg != NULL) /* restore order */ |
214 |
qsort(div, ndivs, sizeof(AMBSAMP), ambnorm); |
215 |
} |
216 |
/* compute returned values */ |
217 |
if (div != NULL) { |
218 |
arad = 0.0; |
219 |
for (i = ndivs, dp = div; i-- > 0; dp++) { |
220 |
arad += dp->r; |
221 |
if (dp->n > 1) { |
222 |
b = 1.0/dp->n; |
223 |
scalecolor(dp->v, b); |
224 |
dp->r *= b; |
225 |
dp->n = 1; |
226 |
} |
227 |
addcolor(acol, dp->v); |
228 |
} |
229 |
b = bright(acol); |
230 |
if (b > FTINY) { |
231 |
b = ndivs/b; |
232 |
if (pg != NULL) { |
233 |
posgradient(pg, div, &hemi); |
234 |
for (i = 0; i < 3; i++) |
235 |
pg[i] *= b; |
236 |
} |
237 |
if (dg != NULL) { |
238 |
dirgradient(dg, div, &hemi); |
239 |
for (i = 0; i < 3; i++) |
240 |
dg[i] *= b; |
241 |
} |
242 |
} else { |
243 |
if (pg != NULL) |
244 |
for (i = 0; i < 3; i++) |
245 |
pg[i] = 0.0; |
246 |
if (dg != NULL) |
247 |
for (i = 0; i < 3; i++) |
248 |
dg[i] = 0.0; |
249 |
} |
250 |
free((void *)div); |
251 |
} |
252 |
b = 1.0/ndivs; |
253 |
scalecolor(acol, b); |
254 |
if (arad <= FTINY) |
255 |
arad = maxarad; |
256 |
else |
257 |
arad = (ndivs+ns)/arad; |
258 |
if (pg != NULL) { /* reduce radius if gradient large */ |
259 |
d = DOT(pg,pg); |
260 |
if (d*arad*arad > 1.0) |
261 |
arad = 1.0/sqrt(d); |
262 |
} |
263 |
if (arad < minarad) { |
264 |
arad = minarad; |
265 |
if (pg != NULL && d*arad*arad > 1.0) { /* cap gradient */ |
266 |
d = 1.0/arad/sqrt(d); |
267 |
for (i = 0; i < 3; i++) |
268 |
pg[i] *= d; |
269 |
} |
270 |
} |
271 |
if ((arad /= sqrt(wt)) > maxarad) |
272 |
arad = maxarad; |
273 |
return(arad); |
274 |
oopsy: |
275 |
if (div != NULL) |
276 |
free((void *)div); |
277 |
return(0.0); |
278 |
} |
279 |
|
280 |
|
281 |
void |
282 |
comperrs( /* compute initial error estimates */ |
283 |
AMBSAMP *da, /* assumes standard ordering */ |
284 |
register AMBHEMI *hp |
285 |
) |
286 |
{ |
287 |
double b, b2; |
288 |
int i, j; |
289 |
register AMBSAMP *dp; |
290 |
/* sum differences from neighbors */ |
291 |
dp = da; |
292 |
for (i = 0; i < hp->nt; i++) |
293 |
for (j = 0; j < hp->np; j++) { |
294 |
#ifdef DEBUG |
295 |
if (dp->t != i || dp->p != j) |
296 |
error(CONSISTENCY, |
297 |
"division order in comperrs"); |
298 |
#endif |
299 |
b = bright(dp[0].v); |
300 |
if (i > 0) { /* from above */ |
301 |
b2 = bright(dp[-hp->np].v) - b; |
302 |
b2 *= b2 * 0.25; |
303 |
dp[0].k += b2; |
304 |
dp[-hp->np].k += b2; |
305 |
} |
306 |
if (j > 0) { /* from behind */ |
307 |
b2 = bright(dp[-1].v) - b; |
308 |
b2 *= b2 * 0.25; |
309 |
dp[0].k += b2; |
310 |
dp[-1].k += b2; |
311 |
} else { /* around */ |
312 |
b2 = bright(dp[hp->np-1].v) - b; |
313 |
b2 *= b2 * 0.25; |
314 |
dp[0].k += b2; |
315 |
dp[hp->np-1].k += b2; |
316 |
} |
317 |
dp++; |
318 |
} |
319 |
/* divide by number of neighbors */ |
320 |
dp = da; |
321 |
for (j = 0; j < hp->np; j++) /* top row */ |
322 |
(dp++)->k *= 1.0/3.0; |
323 |
if (hp->nt < 2) |
324 |
return; |
325 |
for (i = 1; i < hp->nt-1; i++) /* central region */ |
326 |
for (j = 0; j < hp->np; j++) |
327 |
(dp++)->k *= 0.25; |
328 |
for (j = 0; j < hp->np; j++) /* bottom row */ |
329 |
(dp++)->k *= 1.0/3.0; |
330 |
} |
331 |
|
332 |
|
333 |
void |
334 |
posgradient( /* compute position gradient */ |
335 |
FVECT gv, |
336 |
AMBSAMP *da, /* assumes standard ordering */ |
337 |
register AMBHEMI *hp |
338 |
) |
339 |
{ |
340 |
register int i, j; |
341 |
double nextsine, lastsine, b, d; |
342 |
double mag0, mag1; |
343 |
double phi, cosp, sinp, xd, yd; |
344 |
register AMBSAMP *dp; |
345 |
|
346 |
xd = yd = 0.0; |
347 |
for (j = 0; j < hp->np; j++) { |
348 |
dp = da + j; |
349 |
mag0 = mag1 = 0.0; |
350 |
lastsine = 0.0; |
351 |
for (i = 0; i < hp->nt; i++) { |
352 |
#ifdef DEBUG |
353 |
if (dp->t != i || dp->p != j) |
354 |
error(CONSISTENCY, |
355 |
"division order in posgradient"); |
356 |
#endif |
357 |
b = bright(dp->v); |
358 |
if (i > 0) { |
359 |
d = dp[-hp->np].r; |
360 |
if (dp[0].r > d) d = dp[0].r; |
361 |
/* sin(t)*cos(t)^2 */ |
362 |
d *= lastsine * (1.0 - (double)i/hp->nt); |
363 |
mag0 += d*(b - bright(dp[-hp->np].v)); |
364 |
} |
365 |
nextsine = sqrt((double)(i+1)/hp->nt); |
366 |
if (j > 0) { |
367 |
d = dp[-1].r; |
368 |
if (dp[0].r > d) d = dp[0].r; |
369 |
mag1 += d * (nextsine - lastsine) * |
370 |
(b - bright(dp[-1].v)); |
371 |
} else { |
372 |
d = dp[hp->np-1].r; |
373 |
if (dp[0].r > d) d = dp[0].r; |
374 |
mag1 += d * (nextsine - lastsine) * |
375 |
(b - bright(dp[hp->np-1].v)); |
376 |
} |
377 |
dp += hp->np; |
378 |
lastsine = nextsine; |
379 |
} |
380 |
mag0 *= 2.0*PI / hp->np; |
381 |
phi = 2.0*PI * (double)j/hp->np; |
382 |
cosp = tcos(phi); sinp = tsin(phi); |
383 |
xd += mag0*cosp - mag1*sinp; |
384 |
yd += mag0*sinp + mag1*cosp; |
385 |
} |
386 |
for (i = 0; i < 3; i++) |
387 |
gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])/PI; |
388 |
} |
389 |
|
390 |
|
391 |
void |
392 |
dirgradient( /* compute direction gradient */ |
393 |
FVECT gv, |
394 |
AMBSAMP *da, /* assumes standard ordering */ |
395 |
register AMBHEMI *hp |
396 |
) |
397 |
{ |
398 |
register int i, j; |
399 |
double mag; |
400 |
double phi, xd, yd; |
401 |
register AMBSAMP *dp; |
402 |
|
403 |
xd = yd = 0.0; |
404 |
for (j = 0; j < hp->np; j++) { |
405 |
dp = da + j; |
406 |
mag = 0.0; |
407 |
for (i = 0; i < hp->nt; i++) { |
408 |
#ifdef DEBUG |
409 |
if (dp->t != i || dp->p != j) |
410 |
error(CONSISTENCY, |
411 |
"division order in dirgradient"); |
412 |
#endif |
413 |
/* tan(t) */ |
414 |
mag += bright(dp->v)/sqrt(hp->nt/(i+.5) - 1.0); |
415 |
dp += hp->np; |
416 |
} |
417 |
phi = 2.0*PI * (j+.5)/hp->np + PI/2.0; |
418 |
xd += mag * tcos(phi); |
419 |
yd += mag * tsin(phi); |
420 |
} |
421 |
for (i = 0; i < 3; i++) |
422 |
gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])/(hp->nt*hp->np); |
423 |
} |