| 1 |
/* Copyright (c) 1991 Regents of the University of California */ |
| 2 |
|
| 3 |
#ifndef lint |
| 4 |
static char SCCSid[] = "$SunId$ LBL"; |
| 5 |
#endif |
| 6 |
|
| 7 |
/* |
| 8 |
* Routines to compute "ambient" values using Monte Carlo |
| 9 |
*/ |
| 10 |
|
| 11 |
#include "ray.h" |
| 12 |
|
| 13 |
#include "ambient.h" |
| 14 |
|
| 15 |
#include "random.h" |
| 16 |
|
| 17 |
typedef struct { |
| 18 |
short t, p; /* theta, phi indices */ |
| 19 |
COLOR v; /* value sum */ |
| 20 |
float r; /* 1/distance sum */ |
| 21 |
float k; /* variance for this division */ |
| 22 |
int n; /* number of subsamples */ |
| 23 |
} AMBSAMP; /* ambient sample division */ |
| 24 |
|
| 25 |
typedef struct { |
| 26 |
FVECT ux, uy, uz; /* x, y and z axis directions */ |
| 27 |
short nt, np; /* number of theta and phi directions */ |
| 28 |
} AMBHEMI; /* ambient sample hemisphere */ |
| 29 |
|
| 30 |
extern double sin(), cos(), sqrt(); |
| 31 |
|
| 32 |
|
| 33 |
static int |
| 34 |
ambcmp(d1, d2) /* decreasing order */ |
| 35 |
AMBSAMP *d1, *d2; |
| 36 |
{ |
| 37 |
if (d1->k < d2->k) |
| 38 |
return(1); |
| 39 |
if (d1->k > d2->k) |
| 40 |
return(-1); |
| 41 |
return(0); |
| 42 |
} |
| 43 |
|
| 44 |
|
| 45 |
static int |
| 46 |
ambnorm(d1, d2) /* standard order */ |
| 47 |
AMBSAMP *d1, *d2; |
| 48 |
{ |
| 49 |
register int c; |
| 50 |
|
| 51 |
if (c = d1->t - d2->t) |
| 52 |
return(c); |
| 53 |
return(d1->p - d2->p); |
| 54 |
} |
| 55 |
|
| 56 |
|
| 57 |
divsample(dp, h, r) /* sample a division */ |
| 58 |
register AMBSAMP *dp; |
| 59 |
AMBHEMI *h; |
| 60 |
RAY *r; |
| 61 |
{ |
| 62 |
RAY ar; |
| 63 |
int hlist[3]; |
| 64 |
double spt[2]; |
| 65 |
double xd, yd, zd; |
| 66 |
double b2; |
| 67 |
double phi; |
| 68 |
register int i; |
| 69 |
|
| 70 |
if (rayorigin(&ar, r, AMBIENT, AVGREFL) < 0) |
| 71 |
return(-1); |
| 72 |
hlist[0] = r->rno; |
| 73 |
hlist[1] = dp->t; |
| 74 |
hlist[2] = dp->p; |
| 75 |
multisamp(spt, 2, urand(ilhash(hlist,3)+dp->n)); |
| 76 |
zd = sqrt((dp->t + spt[0])/h->nt); |
| 77 |
phi = 2.0*PI * (dp->p + spt[1])/h->np; |
| 78 |
xd = cos(phi) * zd; |
| 79 |
yd = sin(phi) * zd; |
| 80 |
zd = sqrt(1.0 - zd*zd); |
| 81 |
for (i = 0; i < 3; i++) |
| 82 |
ar.rdir[i] = xd*h->ux[i] + |
| 83 |
yd*h->uy[i] + |
| 84 |
zd*h->uz[i]; |
| 85 |
dimlist[ndims++] = dp->t*h->np + dp->p + 90171; |
| 86 |
rayvalue(&ar); |
| 87 |
ndims--; |
| 88 |
addcolor(dp->v, ar.rcol); |
| 89 |
if (ar.rt > FTINY && ar.rt < FHUGE) |
| 90 |
dp->r += 1.0/ar.rt; |
| 91 |
/* (re)initialize error */ |
| 92 |
if (dp->n++) { |
| 93 |
b2 = bright(dp->v)/dp->n - bright(ar.rcol); |
| 94 |
b2 = b2*b2 + dp->k*((dp->n-1)*(dp->n-1)); |
| 95 |
dp->k = b2/(dp->n*dp->n); |
| 96 |
} else |
| 97 |
dp->k = 0.0; |
| 98 |
return(0); |
| 99 |
} |
| 100 |
|
| 101 |
|
| 102 |
double |
| 103 |
doambient(acol, r, wt, pg, dg) /* compute ambient component */ |
| 104 |
COLOR acol; |
| 105 |
RAY *r; |
| 106 |
double wt; |
| 107 |
FVECT pg, dg; |
| 108 |
{ |
| 109 |
double b, d; |
| 110 |
AMBHEMI hemi; |
| 111 |
AMBSAMP *div; |
| 112 |
AMBSAMP dnew; |
| 113 |
register AMBSAMP *dp; |
| 114 |
double arad; |
| 115 |
int ndivs, ns; |
| 116 |
register int i, j; |
| 117 |
/* initialize color */ |
| 118 |
setcolor(acol, 0.0, 0.0, 0.0); |
| 119 |
/* initialize hemisphere */ |
| 120 |
inithemi(&hemi, r, wt); |
| 121 |
ndivs = hemi.nt * hemi.np; |
| 122 |
if (ndivs == 0) |
| 123 |
return(0.0); |
| 124 |
/* set number of super-samples */ |
| 125 |
ns = ambssamp * wt + 0.5; |
| 126 |
if (ns > 0 || pg != NULL || dg != NULL) { |
| 127 |
div = (AMBSAMP *)malloc(ndivs*sizeof(AMBSAMP)); |
| 128 |
if (div == NULL) |
| 129 |
error(SYSTEM, "out of memory in doambient"); |
| 130 |
} else |
| 131 |
div = NULL; |
| 132 |
/* sample the divisions */ |
| 133 |
arad = 0.0; |
| 134 |
if ((dp = div) == NULL) |
| 135 |
dp = &dnew; |
| 136 |
for (i = 0; i < hemi.nt; i++) |
| 137 |
for (j = 0; j < hemi.np; j++) { |
| 138 |
dp->t = i; dp->p = j; |
| 139 |
setcolor(dp->v, 0.0, 0.0, 0.0); |
| 140 |
dp->r = 0.0; |
| 141 |
dp->n = 0; |
| 142 |
if (divsample(dp, &hemi, r) < 0) |
| 143 |
goto oopsy; |
| 144 |
if (div != NULL) |
| 145 |
dp++; |
| 146 |
else { |
| 147 |
addcolor(acol, dp->v); |
| 148 |
arad += dp->r; |
| 149 |
} |
| 150 |
} |
| 151 |
if (ns > 0) { /* perform super-sampling */ |
| 152 |
comperrs(div, &hemi); /* compute errors */ |
| 153 |
qsort(div, ndivs, sizeof(AMBSAMP), ambcmp); /* sort divs */ |
| 154 |
/* super-sample */ |
| 155 |
for (i = ns; i > 0; i--) { |
| 156 |
copystruct(&dnew, div); |
| 157 |
if (divsample(&dnew, &hemi, r) < 0) |
| 158 |
goto oopsy; |
| 159 |
/* reinsert */ |
| 160 |
dp = div; |
| 161 |
j = ndivs < i ? ndivs : i; |
| 162 |
while (--j > 0 && dnew.k < dp[1].k) { |
| 163 |
copystruct(dp, dp+1); |
| 164 |
dp++; |
| 165 |
} |
| 166 |
copystruct(dp, &dnew); |
| 167 |
} |
| 168 |
if (pg != NULL || dg != NULL) /* restore order */ |
| 169 |
qsort(div, ndivs, sizeof(AMBSAMP), ambnorm); |
| 170 |
} |
| 171 |
/* compute returned values */ |
| 172 |
if (div != NULL) { |
| 173 |
for (i = ndivs, dp = div; i-- > 0; dp++) { |
| 174 |
arad += dp->r; |
| 175 |
if (dp->n > 1) { |
| 176 |
b = 1.0/dp->n; |
| 177 |
scalecolor(dp->v, b); |
| 178 |
dp->r *= b; |
| 179 |
dp->n = 1; |
| 180 |
} |
| 181 |
addcolor(acol, dp->v); |
| 182 |
} |
| 183 |
b = bright(acol); |
| 184 |
if (b > FTINY) { |
| 185 |
b = ndivs/b; |
| 186 |
if (pg != NULL) { |
| 187 |
posgradient(pg, div, &hemi); |
| 188 |
for (i = 0; i < 3; i++) |
| 189 |
pg[i] *= b; |
| 190 |
} |
| 191 |
if (dg != NULL) { |
| 192 |
dirgradient(dg, div, &hemi); |
| 193 |
for (i = 0; i < 3; i++) |
| 194 |
dg[i] *= b; |
| 195 |
} |
| 196 |
} else { |
| 197 |
if (pg != NULL) |
| 198 |
for (i = 0; i < 3; i++) |
| 199 |
pg[i] = 0.0; |
| 200 |
if (dg != NULL) |
| 201 |
for (i = 0; i < 3; i++) |
| 202 |
dg[i] = 0.0; |
| 203 |
} |
| 204 |
free((char *)div); |
| 205 |
} |
| 206 |
b = 1.0/ndivs; |
| 207 |
scalecolor(acol, b); |
| 208 |
if (arad <= FTINY) |
| 209 |
arad = FHUGE; |
| 210 |
else |
| 211 |
arad = (ndivs+ns)/arad; |
| 212 |
if (pg != NULL) { /* reduce radius if gradient large */ |
| 213 |
d = DOT(pg,pg); |
| 214 |
if (d*arad*arad > 1.0) |
| 215 |
arad = 1.0/sqrt(d); |
| 216 |
} |
| 217 |
if (arad > maxarad) |
| 218 |
arad = maxarad; |
| 219 |
else if (arad < minarad) |
| 220 |
arad = minarad; |
| 221 |
return(arad/sqrt(wt)); |
| 222 |
oopsy: |
| 223 |
if (div != NULL) |
| 224 |
free((char *)div); |
| 225 |
return(0.0); |
| 226 |
} |
| 227 |
|
| 228 |
|
| 229 |
inithemi(hp, r, wt) /* initialize sampling hemisphere */ |
| 230 |
register AMBHEMI *hp; |
| 231 |
RAY *r; |
| 232 |
double wt; |
| 233 |
{ |
| 234 |
register int i; |
| 235 |
/* set number of divisions */ |
| 236 |
if (wt < (.25*PI)/ambdiv+FTINY) { |
| 237 |
hp->nt = hp->np = 0; |
| 238 |
return; /* zero samples */ |
| 239 |
} |
| 240 |
hp->nt = sqrt(ambdiv * wt / PI) + 0.5; |
| 241 |
hp->np = PI * hp->nt + 0.5; |
| 242 |
/* make axes */ |
| 243 |
VCOPY(hp->uz, r->ron); |
| 244 |
hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0; |
| 245 |
for (i = 0; i < 3; i++) |
| 246 |
if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6) |
| 247 |
break; |
| 248 |
if (i >= 3) |
| 249 |
error(CONSISTENCY, "bad ray direction in inithemi"); |
| 250 |
hp->uy[i] = 1.0; |
| 251 |
fcross(hp->ux, hp->uy, hp->uz); |
| 252 |
normalize(hp->ux); |
| 253 |
fcross(hp->uy, hp->uz, hp->ux); |
| 254 |
} |
| 255 |
|
| 256 |
|
| 257 |
comperrs(da, hp) /* compute initial error estimates */ |
| 258 |
AMBSAMP *da; /* assumes standard ordering */ |
| 259 |
register AMBHEMI *hp; |
| 260 |
{ |
| 261 |
double b, b2; |
| 262 |
int i, j; |
| 263 |
register AMBSAMP *dp; |
| 264 |
/* sum differences from neighbors */ |
| 265 |
dp = da; |
| 266 |
for (i = 0; i < hp->nt; i++) |
| 267 |
for (j = 0; j < hp->np; j++) { |
| 268 |
#ifdef DEBUG |
| 269 |
if (dp->t != i || dp->p != j) |
| 270 |
error(CONSISTENCY, |
| 271 |
"division order in comperrs"); |
| 272 |
#endif |
| 273 |
b = bright(dp[0].v); |
| 274 |
if (i > 0) { /* from above */ |
| 275 |
b2 = bright(dp[-hp->np].v) - b; |
| 276 |
b2 *= b2 * 0.25; |
| 277 |
dp[0].k += b2; |
| 278 |
dp[-hp->np].k += b2; |
| 279 |
} |
| 280 |
if (j > 0) { /* from behind */ |
| 281 |
b2 = bright(dp[-1].v) - b; |
| 282 |
b2 *= b2 * 0.25; |
| 283 |
dp[0].k += b2; |
| 284 |
dp[-1].k += b2; |
| 285 |
} else { /* around */ |
| 286 |
b2 = bright(dp[hp->np-1].v) - b; |
| 287 |
b2 *= b2 * 0.25; |
| 288 |
dp[0].k += b2; |
| 289 |
dp[hp->np-1].k += b2; |
| 290 |
} |
| 291 |
dp++; |
| 292 |
} |
| 293 |
/* divide by number of neighbors */ |
| 294 |
dp = da; |
| 295 |
for (j = 0; j < hp->np; j++) /* top row */ |
| 296 |
(dp++)->k *= 1.0/3.0; |
| 297 |
if (hp->nt < 2) |
| 298 |
return; |
| 299 |
for (i = 1; i < hp->nt-1; i++) /* central region */ |
| 300 |
for (j = 0; j < hp->np; j++) |
| 301 |
(dp++)->k *= 0.25; |
| 302 |
for (j = 0; j < hp->np; j++) /* bottom row */ |
| 303 |
(dp++)->k *= 1.0/3.0; |
| 304 |
} |
| 305 |
|
| 306 |
|
| 307 |
posgradient(gv, da, hp) /* compute position gradient */ |
| 308 |
FVECT gv; |
| 309 |
AMBSAMP *da; /* assumes standard ordering */ |
| 310 |
AMBHEMI *hp; |
| 311 |
{ |
| 312 |
register int i, j; |
| 313 |
double b, d; |
| 314 |
double mag0, mag1; |
| 315 |
double phi, cosp, sinp, xd, yd; |
| 316 |
register AMBSAMP *dp; |
| 317 |
|
| 318 |
xd = yd = 0.0; |
| 319 |
for (j = 0; j < hp->np; j++) { |
| 320 |
dp = da + j; |
| 321 |
mag0 = mag1 = 0.0; |
| 322 |
for (i = 0; i < hp->nt; i++) { |
| 323 |
#ifdef DEBUG |
| 324 |
if (dp->t != i || dp->p != j) |
| 325 |
error(CONSISTENCY, |
| 326 |
"division order in posgradient"); |
| 327 |
#endif |
| 328 |
b = bright(dp->v); |
| 329 |
if (i > 0) { |
| 330 |
d = dp[-hp->np].r; |
| 331 |
if (dp[0].r > d) d = dp[0].r; |
| 332 |
d *= 1.0 - (double)i/hp->nt; /* cos(t)^2 */ |
| 333 |
mag0 += d*(b - bright(dp[-hp->np].v)); |
| 334 |
} |
| 335 |
if (j > 0) { |
| 336 |
d = dp[-1].r; |
| 337 |
if (dp[0].r > d) d = dp[0].r; |
| 338 |
mag1 += d*(b - bright(dp[-1].v)); |
| 339 |
} else { |
| 340 |
d = dp[hp->np-1].r; |
| 341 |
if (dp[0].r > d) d = dp[0].r; |
| 342 |
mag1 += d*(b - bright(dp[hp->np-1].v)); |
| 343 |
} |
| 344 |
dp += hp->np; |
| 345 |
} |
| 346 |
if (hp->nt > 1) { |
| 347 |
mag0 /= (double)hp->np; |
| 348 |
mag1 /= (double)hp->nt; |
| 349 |
} |
| 350 |
phi = 2.0*PI * (double)j/hp->np; |
| 351 |
cosp = cos(phi); sinp = sin(phi); |
| 352 |
xd += mag0*cosp - mag1*sinp; |
| 353 |
yd += mag0*sinp + mag1*cosp; |
| 354 |
} |
| 355 |
for (i = 0; i < 3; i++) |
| 356 |
gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])/PI; |
| 357 |
} |
| 358 |
|
| 359 |
|
| 360 |
dirgradient(gv, da, hp) /* compute direction gradient */ |
| 361 |
FVECT gv; |
| 362 |
AMBSAMP *da; /* assumes standard ordering */ |
| 363 |
AMBHEMI *hp; |
| 364 |
{ |
| 365 |
register int i, j; |
| 366 |
double mag; |
| 367 |
double phi, xd, yd; |
| 368 |
register AMBSAMP *dp; |
| 369 |
|
| 370 |
xd = yd = 0.0; |
| 371 |
for (j = 0; j < hp->np; j++) { |
| 372 |
dp = da + j; |
| 373 |
mag = 0.0; |
| 374 |
for (i = 0; i < hp->nt; i++) { |
| 375 |
#ifdef DEBUG |
| 376 |
if (dp->t != i || dp->p != j) |
| 377 |
error(CONSISTENCY, |
| 378 |
"division order in dirgradient"); |
| 379 |
#endif |
| 380 |
mag += sqrt((i+.5)/hp->nt)*bright(dp->v); /* sin(t) */ |
| 381 |
dp += hp->np; |
| 382 |
} |
| 383 |
phi = 2.0*PI * (j+.5)/hp->np + PI/2.0; |
| 384 |
xd += mag * cos(phi); |
| 385 |
yd += mag * sin(phi); |
| 386 |
} |
| 387 |
for (i = 0; i < 3; i++) |
| 388 |
gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])*PI/(hp->nt*hp->np); |
| 389 |
} |
