1 |
#ifndef lint |
2 |
static const char RCSid[] = "$Id: ambcomp.c,v 2.15 2005/05/28 22:27:54 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 |
void |
20 |
inithemi( /* initialize sampling hemisphere */ |
21 |
register AMBHEMI *hp, |
22 |
COLOR ac, |
23 |
RAY *r, |
24 |
double wt |
25 |
) |
26 |
{ |
27 |
double d; |
28 |
register int i; |
29 |
/* set number of divisions */ |
30 |
if (ambacc <= FTINY && |
31 |
wt > (d = 0.8*bright(ac)*r->rweight/(ambdiv*minweight))) |
32 |
wt = d; /* avoid ray termination */ |
33 |
hp->nt = sqrt(ambdiv * wt / PI) + 0.5; |
34 |
i = ambacc > FTINY ? 3 : 1; /* minimum number of samples */ |
35 |
if (hp->nt < i) |
36 |
hp->nt = i; |
37 |
hp->np = PI * hp->nt + 0.5; |
38 |
/* set number of super-samples */ |
39 |
hp->ns = ambssamp * wt + 0.5; |
40 |
/* assign coefficient */ |
41 |
copycolor(hp->acoef, ac); |
42 |
d = 1.0/(hp->nt*hp->np); |
43 |
scalecolor(hp->acoef, d); |
44 |
/* make axes */ |
45 |
VCOPY(hp->uz, r->ron); |
46 |
hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0; |
47 |
for (i = 0; i < 3; i++) |
48 |
if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6) |
49 |
break; |
50 |
if (i >= 3) |
51 |
error(CONSISTENCY, "bad ray direction in inithemi"); |
52 |
hp->uy[i] = 1.0; |
53 |
fcross(hp->ux, hp->uy, hp->uz); |
54 |
normalize(hp->ux); |
55 |
fcross(hp->uy, hp->uz, hp->ux); |
56 |
} |
57 |
|
58 |
|
59 |
int |
60 |
divsample( /* sample a division */ |
61 |
register AMBSAMP *dp, |
62 |
AMBHEMI *h, |
63 |
RAY *r |
64 |
) |
65 |
{ |
66 |
RAY ar; |
67 |
int hlist[3]; |
68 |
double spt[2]; |
69 |
double xd, yd, zd; |
70 |
double b2; |
71 |
double phi; |
72 |
register int i; |
73 |
/* ambient coefficient for weight */ |
74 |
if (ambacc > FTINY) |
75 |
setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL); |
76 |
else |
77 |
copycolor(ar.rcoef, h->acoef); |
78 |
if (rayorigin(&ar, AMBIENT, r, ar.rcoef) < 0) |
79 |
return(-1); |
80 |
if (ambacc > FTINY) |
81 |
copycolor(ar.rcoef, h->acoef); |
82 |
hlist[0] = r->rno; |
83 |
hlist[1] = dp->t; |
84 |
hlist[2] = dp->p; |
85 |
multisamp(spt, 2, urand(ilhash(hlist,3)+dp->n)); |
86 |
zd = sqrt((dp->t + spt[0])/h->nt); |
87 |
phi = 2.0*PI * (dp->p + spt[1])/h->np; |
88 |
xd = tcos(phi) * zd; |
89 |
yd = tsin(phi) * zd; |
90 |
zd = sqrt(1.0 - zd*zd); |
91 |
for (i = 0; i < 3; i++) |
92 |
ar.rdir[i] = xd*h->ux[i] + |
93 |
yd*h->uy[i] + |
94 |
zd*h->uz[i]; |
95 |
dimlist[ndims++] = dp->t*h->np + dp->p + 90171; |
96 |
rayvalue(&ar); |
97 |
ndims--; |
98 |
multcolor(ar.rcol, ar.rcoef); /* apply coefficient */ |
99 |
addcolor(dp->v, ar.rcol); |
100 |
/* use rt to improve gradient calc */ |
101 |
if (ar.rt > FTINY && ar.rt < FHUGE) |
102 |
dp->r += 1.0/ar.rt; |
103 |
/* (re)initialize error */ |
104 |
if (dp->n++) { |
105 |
b2 = bright(dp->v)/dp->n - bright(ar.rcol); |
106 |
b2 = b2*b2 + dp->k*((dp->n-1)*(dp->n-1)); |
107 |
dp->k = b2/(dp->n*dp->n); |
108 |
} else |
109 |
dp->k = 0.0; |
110 |
return(0); |
111 |
} |
112 |
|
113 |
|
114 |
static int |
115 |
ambcmp( /* decreasing order */ |
116 |
const void *p1, |
117 |
const void *p2 |
118 |
) |
119 |
{ |
120 |
const AMBSAMP *d1 = (const AMBSAMP *)p1; |
121 |
const AMBSAMP *d2 = (const AMBSAMP *)p2; |
122 |
|
123 |
if (d1->k < d2->k) |
124 |
return(1); |
125 |
if (d1->k > d2->k) |
126 |
return(-1); |
127 |
return(0); |
128 |
} |
129 |
|
130 |
|
131 |
static int |
132 |
ambnorm( /* standard order */ |
133 |
const void *p1, |
134 |
const void *p2 |
135 |
) |
136 |
{ |
137 |
const AMBSAMP *d1 = (const AMBSAMP *)p1; |
138 |
const AMBSAMP *d2 = (const AMBSAMP *)p2; |
139 |
register int c; |
140 |
|
141 |
if ( (c = d1->t - d2->t) ) |
142 |
return(c); |
143 |
return(d1->p - d2->p); |
144 |
} |
145 |
|
146 |
|
147 |
double |
148 |
doambient( /* compute ambient component */ |
149 |
COLOR acol, |
150 |
RAY *r, |
151 |
double wt, |
152 |
FVECT pg, |
153 |
FVECT dg |
154 |
) |
155 |
{ |
156 |
double b, d; |
157 |
AMBHEMI hemi; |
158 |
AMBSAMP *div; |
159 |
AMBSAMP dnew; |
160 |
register AMBSAMP *dp; |
161 |
double arad; |
162 |
int ndivs; |
163 |
register int i, j; |
164 |
/* initialize hemisphere */ |
165 |
inithemi(&hemi, acol, r, wt); |
166 |
ndivs = hemi.nt * hemi.np; |
167 |
/* initialize sum */ |
168 |
setcolor(acol, 0.0, 0.0, 0.0); |
169 |
if (ndivs == 0) |
170 |
return(0.0); |
171 |
/* allocate super-samples */ |
172 |
if (hemi.ns > 0 || pg != NULL || dg != NULL) { |
173 |
div = (AMBSAMP *)malloc(ndivs*sizeof(AMBSAMP)); |
174 |
if (div == NULL) |
175 |
error(SYSTEM, "out of memory in doambient"); |
176 |
} else |
177 |
div = NULL; |
178 |
/* sample the divisions */ |
179 |
arad = 0.0; |
180 |
if ((dp = div) == NULL) |
181 |
dp = &dnew; |
182 |
for (i = 0; i < hemi.nt; i++) |
183 |
for (j = 0; j < hemi.np; j++) { |
184 |
dp->t = i; dp->p = j; |
185 |
setcolor(dp->v, 0.0, 0.0, 0.0); |
186 |
dp->r = 0.0; |
187 |
dp->n = 0; |
188 |
if (divsample(dp, &hemi, r) < 0) { |
189 |
if (div != NULL) dp++; |
190 |
continue; |
191 |
} |
192 |
arad += dp->r; |
193 |
if (div != NULL) |
194 |
dp++; |
195 |
else |
196 |
addcolor(acol, dp->v); |
197 |
} |
198 |
if (hemi.ns > 0 && arad > FTINY && ndivs/arad < minarad) |
199 |
hemi.ns = 0; /* close enough */ |
200 |
else if (hemi.ns > 0) { /* else perform super-sampling */ |
201 |
comperrs(div, &hemi); /* compute errors */ |
202 |
qsort(div, ndivs, sizeof(AMBSAMP), ambcmp); /* sort divs */ |
203 |
/* super-sample */ |
204 |
for (i = hemi.ns; i > 0; i--) { |
205 |
dnew = *div; |
206 |
if (divsample(&dnew, &hemi, r) < 0) { |
207 |
dp++; |
208 |
continue; |
209 |
} |
210 |
dp = div; /* reinsert */ |
211 |
j = ndivs < i ? ndivs : i; |
212 |
while (--j > 0 && dnew.k < dp[1].k) { |
213 |
*dp = *(dp+1); |
214 |
dp++; |
215 |
} |
216 |
*dp = dnew; |
217 |
} |
218 |
if (pg != NULL || dg != NULL) /* restore order */ |
219 |
qsort(div, ndivs, sizeof(AMBSAMP), ambnorm); |
220 |
} |
221 |
/* compute returned values */ |
222 |
if (div != NULL) { |
223 |
arad = 0.0; |
224 |
for (i = ndivs, dp = div; i-- > 0; dp++) { |
225 |
arad += dp->r; |
226 |
if (dp->n > 1) { |
227 |
b = 1.0/dp->n; |
228 |
scalecolor(dp->v, b); |
229 |
dp->r *= b; |
230 |
dp->n = 1; |
231 |
} |
232 |
addcolor(acol, dp->v); |
233 |
} |
234 |
b = bright(acol); |
235 |
if (b > FTINY) { |
236 |
b = 1.0/b; /* normalize gradient(s) */ |
237 |
if (pg != NULL) { |
238 |
posgradient(pg, div, &hemi); |
239 |
for (i = 0; i < 3; i++) |
240 |
pg[i] *= b; |
241 |
} |
242 |
if (dg != NULL) { |
243 |
dirgradient(dg, div, &hemi); |
244 |
for (i = 0; i < 3; i++) |
245 |
dg[i] *= b; |
246 |
} |
247 |
} else { |
248 |
if (pg != NULL) |
249 |
for (i = 0; i < 3; i++) |
250 |
pg[i] = 0.0; |
251 |
if (dg != NULL) |
252 |
for (i = 0; i < 3; i++) |
253 |
dg[i] = 0.0; |
254 |
} |
255 |
free((void *)div); |
256 |
} |
257 |
if (arad <= FTINY) |
258 |
arad = maxarad; |
259 |
else |
260 |
arad = (ndivs+hemi.ns)/arad; |
261 |
if (pg != NULL) { /* reduce radius if gradient large */ |
262 |
d = DOT(pg,pg); |
263 |
if (d*arad*arad > 1.0) |
264 |
arad = 1.0/sqrt(d); |
265 |
} |
266 |
if (arad < minarad) { |
267 |
arad = minarad; |
268 |
if (pg != NULL && d*arad*arad > 1.0) { /* cap gradient */ |
269 |
d = 1.0/arad/sqrt(d); |
270 |
for (i = 0; i < 3; i++) |
271 |
pg[i] *= d; |
272 |
} |
273 |
} |
274 |
if ((arad /= sqrt(wt)) > maxarad) |
275 |
arad = maxarad; |
276 |
return(arad); |
277 |
} |
278 |
|
279 |
|
280 |
void |
281 |
comperrs( /* compute initial error estimates */ |
282 |
AMBSAMP *da, /* assumes standard ordering */ |
283 |
register AMBHEMI *hp |
284 |
) |
285 |
{ |
286 |
double b, b2; |
287 |
int i, j; |
288 |
register AMBSAMP *dp; |
289 |
/* sum differences from neighbors */ |
290 |
dp = da; |
291 |
for (i = 0; i < hp->nt; i++) |
292 |
for (j = 0; j < hp->np; j++) { |
293 |
#ifdef DEBUG |
294 |
if (dp->t != i || dp->p != j) |
295 |
error(CONSISTENCY, |
296 |
"division order in comperrs"); |
297 |
#endif |
298 |
b = bright(dp[0].v); |
299 |
if (i > 0) { /* from above */ |
300 |
b2 = bright(dp[-hp->np].v) - b; |
301 |
b2 *= b2 * 0.25; |
302 |
dp[0].k += b2; |
303 |
dp[-hp->np].k += b2; |
304 |
} |
305 |
if (j > 0) { /* from behind */ |
306 |
b2 = bright(dp[-1].v) - b; |
307 |
b2 *= b2 * 0.25; |
308 |
dp[0].k += b2; |
309 |
dp[-1].k += b2; |
310 |
} else { /* around */ |
311 |
b2 = bright(dp[hp->np-1].v) - b; |
312 |
b2 *= b2 * 0.25; |
313 |
dp[0].k += b2; |
314 |
dp[hp->np-1].k += b2; |
315 |
} |
316 |
dp++; |
317 |
} |
318 |
/* divide by number of neighbors */ |
319 |
dp = da; |
320 |
for (j = 0; j < hp->np; j++) /* top row */ |
321 |
(dp++)->k *= 1.0/3.0; |
322 |
if (hp->nt < 2) |
323 |
return; |
324 |
for (i = 1; i < hp->nt-1; i++) /* central region */ |
325 |
for (j = 0; j < hp->np; j++) |
326 |
(dp++)->k *= 0.25; |
327 |
for (j = 0; j < hp->np; j++) /* bottom row */ |
328 |
(dp++)->k *= 1.0/3.0; |
329 |
} |
330 |
|
331 |
|
332 |
void |
333 |
posgradient( /* compute position gradient */ |
334 |
FVECT gv, |
335 |
AMBSAMP *da, /* assumes standard ordering */ |
336 |
register AMBHEMI *hp |
337 |
) |
338 |
{ |
339 |
register int i, j; |
340 |
double nextsine, lastsine, b, d; |
341 |
double mag0, mag1; |
342 |
double phi, cosp, sinp, xd, yd; |
343 |
register AMBSAMP *dp; |
344 |
|
345 |
xd = yd = 0.0; |
346 |
for (j = 0; j < hp->np; j++) { |
347 |
dp = da + j; |
348 |
mag0 = mag1 = 0.0; |
349 |
lastsine = 0.0; |
350 |
for (i = 0; i < hp->nt; i++) { |
351 |
#ifdef DEBUG |
352 |
if (dp->t != i || dp->p != j) |
353 |
error(CONSISTENCY, |
354 |
"division order in posgradient"); |
355 |
#endif |
356 |
b = bright(dp->v); |
357 |
if (i > 0) { |
358 |
d = dp[-hp->np].r; |
359 |
if (dp[0].r > d) d = dp[0].r; |
360 |
/* sin(t)*cos(t)^2 */ |
361 |
d *= lastsine * (1.0 - (double)i/hp->nt); |
362 |
mag0 += d*(b - bright(dp[-hp->np].v)); |
363 |
} |
364 |
nextsine = sqrt((double)(i+1)/hp->nt); |
365 |
if (j > 0) { |
366 |
d = dp[-1].r; |
367 |
if (dp[0].r > d) d = dp[0].r; |
368 |
mag1 += d * (nextsine - lastsine) * |
369 |
(b - bright(dp[-1].v)); |
370 |
} else { |
371 |
d = dp[hp->np-1].r; |
372 |
if (dp[0].r > d) d = dp[0].r; |
373 |
mag1 += d * (nextsine - lastsine) * |
374 |
(b - bright(dp[hp->np-1].v)); |
375 |
} |
376 |
dp += hp->np; |
377 |
lastsine = nextsine; |
378 |
} |
379 |
mag0 *= 2.0*PI / hp->np; |
380 |
phi = 2.0*PI * (double)j/hp->np; |
381 |
cosp = tcos(phi); sinp = tsin(phi); |
382 |
xd += mag0*cosp - mag1*sinp; |
383 |
yd += mag0*sinp + mag1*cosp; |
384 |
} |
385 |
for (i = 0; i < 3; i++) |
386 |
gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])*(hp->nt*hp->np)/PI; |
387 |
} |
388 |
|
389 |
|
390 |
void |
391 |
dirgradient( /* compute direction gradient */ |
392 |
FVECT gv, |
393 |
AMBSAMP *da, /* assumes standard ordering */ |
394 |
register AMBHEMI *hp |
395 |
) |
396 |
{ |
397 |
register int i, j; |
398 |
double mag; |
399 |
double phi, xd, yd; |
400 |
register AMBSAMP *dp; |
401 |
|
402 |
xd = yd = 0.0; |
403 |
for (j = 0; j < hp->np; j++) { |
404 |
dp = da + j; |
405 |
mag = 0.0; |
406 |
for (i = 0; i < hp->nt; i++) { |
407 |
#ifdef DEBUG |
408 |
if (dp->t != i || dp->p != j) |
409 |
error(CONSISTENCY, |
410 |
"division order in dirgradient"); |
411 |
#endif |
412 |
/* tan(t) */ |
413 |
mag += bright(dp->v)/sqrt(hp->nt/(i+.5) - 1.0); |
414 |
dp += hp->np; |
415 |
} |
416 |
phi = 2.0*PI * (j+.5)/hp->np + PI/2.0; |
417 |
xd += mag * tcos(phi); |
418 |
yd += mag * tsin(phi); |
419 |
} |
420 |
for (i = 0; i < 3; i++) |
421 |
gv[i] = xd*hp->ux[i] + yd*hp->uy[i]; |
422 |
} |