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root/radiance/ray/src/cv/bsdfmesh.c
Revision: 2.30
Committed: Thu Aug 21 10:33:48 2014 UTC (9 years, 7 months ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 2.29: +91 -1 lines
Log Message:
Added grazing angle extrapolation to BSDF interpolation

File Contents

# Content
1 #ifndef lint
2 static const char RCSid[] = "$Id: bsdfmesh.c,v 2.29 2014/03/27 03:49:14 greg Exp $";
3 #endif
4 /*
5 * Create BSDF advection mesh from radial basis functions.
6 *
7 * G. Ward
8 */
9
10 #ifndef _WIN32
11 #include <unistd.h>
12 #include <sys/wait.h>
13 #include <sys/mman.h>
14 #endif
15 #define _USE_MATH_DEFINES
16 #include <stdio.h>
17 #include <stdlib.h>
18 #include <string.h>
19 #include <math.h>
20 #include "bsdfrep.h"
21
22 #ifndef NEIGH_FACT2
23 #define NEIGH_FACT2 0.1 /* empirical neighborhood distance weight */
24 #endif
25 /* number of processes to run */
26 int nprocs = 1;
27 /* number of children (-1 in child) */
28 static int nchild = 0;
29
30 /* Compute average DSF value at the given radius from central vector */
31 static double
32 eval_DSFsurround(const RBFNODE *rbf, const FVECT outvec, const double rad)
33 {
34 const int ninc = 12;
35 const double phinc = 2.*M_PI/ninc;
36 double sum = 0;
37 int n = 0;
38 FVECT tvec;
39 int i;
40 /* compute initial vector */
41 if (output_orient*outvec[2] >= 1.-FTINY) {
42 tvec[0] = tvec[2] = 0;
43 tvec[1] = 1;
44 } else {
45 tvec[0] = tvec[1] = 0;
46 tvec[2] = 1;
47 }
48 geodesic(tvec, outvec, tvec, rad, GEOD_RAD);
49 /* average surrounding DSF */
50 for (i = 0; i < ninc; i++) {
51 if (i) spinvector(tvec, tvec, outvec, phinc);
52 if (tvec[2] > 0 ^ output_orient > 0)
53 continue;
54 sum += eval_rbfrep(rbf, tvec) * output_orient*tvec[2];
55 ++n;
56 }
57 if (n < 2) /* should never happen! */
58 return(sum);
59 return(sum/(double)n);
60 }
61
62 /* Estimate single-lobe radius for DSF at the given outgoing angle */
63 static double
64 est_DSFrad(const RBFNODE *rbf, const FVECT outvec)
65 {
66 const double rad_epsilon = 0.03;
67 const double DSFtarget = 0.60653066 * eval_rbfrep(rbf,outvec)
68 * output_orient*outvec[2];
69 double inside_rad = rad_epsilon;
70 double outside_rad = 0.5;
71 double DSFinside = eval_DSFsurround(rbf, outvec, inside_rad);
72 double DSFoutside = eval_DSFsurround(rbf, outvec, outside_rad);
73 #define interp_rad inside_rad + (outside_rad-inside_rad) * \
74 (DSFtarget-DSFinside) / (DSFoutside-DSFinside)
75 /* interpolation search */
76 while (outside_rad-inside_rad > rad_epsilon) {
77 double test_rad = interp_rad;
78 double DSFtest = eval_DSFsurround(rbf, outvec, test_rad);
79 if (DSFtarget < DSFtest) {
80 inside_rad = test_rad;
81 DSFinside = DSFtest;
82 } else {
83 outside_rad = test_rad;
84 DSFoutside = DSFtest;
85 }
86 }
87 return(interp_rad);
88 #undef interp_rad
89 }
90
91 /* Compute average BSDF peak from current DSF's */
92 static void
93 comp_bsdf_spec(void)
94 {
95 double peak_sum = 0;
96 double rad_sum = 0;
97 int n = 0;
98 RBFNODE *rbf;
99 FVECT sdv;
100
101 if (dsf_list == NULL) {
102 bsdf_spec_peak = 0;
103 bsdf_spec_crad = 0;
104 return;
105 }
106 for (rbf = dsf_list; rbf != NULL; rbf = rbf->next) {
107 sdv[0] = -rbf->invec[0];
108 sdv[1] = -rbf->invec[1];
109 sdv[2] = rbf->invec[2]*(2*(input_orient==output_orient) - 1);
110 peak_sum += eval_rbfrep(rbf, sdv);
111 rad_sum += est_DSFrad(rbf, sdv);
112 ++n;
113 }
114 bsdf_spec_peak = peak_sum/(double)n;
115 bsdf_spec_crad = ANG2R( rad_sum/(double)n );
116 }
117
118 /* Create a new migration holder (sharing memory for multiprocessing) */
119 static MIGRATION *
120 new_migration(RBFNODE *from_rbf, RBFNODE *to_rbf)
121 {
122 size_t memlen = sizeof(MIGRATION) +
123 sizeof(float)*(from_rbf->nrbf*to_rbf->nrbf - 1);
124 MIGRATION *newmig;
125 #ifdef _WIN32
126 if (nprocs > 1)
127 fprintf(stderr, "%s: warning - multiprocessing not supported\n",
128 progname);
129 nprocs = 1;
130 newmig = (MIGRATION *)malloc(memlen);
131 #else
132 if (nprocs <= 1) { /* single process? */
133 newmig = (MIGRATION *)malloc(memlen);
134 } else { /* else need to share memory */
135 newmig = (MIGRATION *)mmap(NULL, memlen, PROT_READ|PROT_WRITE,
136 MAP_ANON|MAP_SHARED, -1, 0);
137 if ((void *)newmig == MAP_FAILED)
138 newmig = NULL;
139 }
140 #endif
141 if (newmig == NULL) {
142 fprintf(stderr, "%s: cannot allocate new migration\n", progname);
143 exit(1);
144 }
145 newmig->rbfv[0] = from_rbf;
146 newmig->rbfv[1] = to_rbf;
147 /* insert in edge lists */
148 newmig->enxt[0] = from_rbf->ejl;
149 from_rbf->ejl = newmig;
150 newmig->enxt[1] = to_rbf->ejl;
151 to_rbf->ejl = newmig;
152 newmig->next = mig_list; /* push onto global list */
153 return(mig_list = newmig);
154 }
155
156 #ifdef _WIN32
157 #define await_children(n) (void)(n)
158 #define run_subprocess() 0
159 #define end_subprocess() (void)0
160 #else
161
162 /* Wait for the specified number of child processes to complete */
163 static void
164 await_children(int n)
165 {
166 int exit_status = 0;
167
168 if (n > nchild)
169 n = nchild;
170 while (n-- > 0) {
171 int status;
172 if (wait(&status) < 0) {
173 fprintf(stderr, "%s: missing child(ren)!\n", progname);
174 nchild = 0;
175 break;
176 }
177 --nchild;
178 if (status) { /* something wrong */
179 if ((status = WEXITSTATUS(status)))
180 exit_status = status;
181 else
182 exit_status += !exit_status;
183 fprintf(stderr, "%s: subprocess died\n", progname);
184 n = nchild; /* wait for the rest */
185 }
186 }
187 if (exit_status)
188 exit(exit_status);
189 }
190
191 /* Start child process if multiprocessing selected */
192 static pid_t
193 run_subprocess(void)
194 {
195 int status;
196 pid_t pid;
197
198 if (nprocs <= 1) /* any children requested? */
199 return(0);
200 await_children(nchild + 1 - nprocs); /* free up child process */
201 if ((pid = fork())) {
202 if (pid < 0) {
203 fprintf(stderr, "%s: cannot fork subprocess\n",
204 progname);
205 await_children(nchild);
206 exit(1);
207 }
208 ++nchild; /* subprocess started */
209 return(pid);
210 }
211 nchild = -1;
212 return(0); /* put child to work */
213 }
214
215 /* If we are in subprocess, call exit */
216 #define end_subprocess() if (nchild < 0) _exit(0); else
217
218 #endif /* ! _WIN32 */
219
220 /* Compute normalized distribution scattering functions for comparison */
221 static void
222 compute_nDSFs(const RBFNODE *rbf0, const RBFNODE *rbf1)
223 {
224 const double nf0 = (GRIDRES*GRIDRES) / rbf0->vtotal;
225 const double nf1 = (GRIDRES*GRIDRES) / rbf1->vtotal;
226 int x, y;
227 FVECT dv;
228
229 for (x = GRIDRES; x--; )
230 for (y = GRIDRES; y--; ) {
231 ovec_from_pos(dv, x, y); /* cube root (brightness) */
232 dsf_grid[x][y].val[0] = pow(nf0*eval_rbfrep(rbf0, dv), .3333);
233 dsf_grid[x][y].val[1] = pow(nf1*eval_rbfrep(rbf1, dv), .3333);
234 }
235 }
236
237 /* Compute neighborhood distance-squared (dissimilarity) */
238 static double
239 neighborhood_dist2(int x0, int y0, int x1, int y1)
240 {
241 int rad = GRIDRES>>5;
242 double sum2 = 0.;
243 double d;
244 int p[4];
245 int i, j;
246 /* check radius */
247 p[0] = x0; p[1] = y0; p[2] = x1; p[3] = y1;
248 for (i = 4; i--; ) {
249 if (p[i] < rad) rad = p[i];
250 if (GRIDRES-1-p[i] < rad) rad = GRIDRES-1-p[i];
251 }
252 for (i = -rad; i <= rad; i++)
253 for (j = -rad; j <= rad; j++) {
254 d = dsf_grid[x0+i][y0+j].val[0] -
255 dsf_grid[x1+i][y1+j].val[1];
256 sum2 += d*d;
257 }
258 return(sum2 / (4*rad*(rad+1) + 1));
259 }
260
261 /* Compute distance between two RBF lobes */
262 double
263 lobe_distance(RBFVAL *rbf1, RBFVAL *rbf2)
264 {
265 FVECT vfrom, vto;
266 double d, res;
267 /* quadratic cost function */
268 ovec_from_pos(vfrom, rbf1->gx, rbf1->gy);
269 ovec_from_pos(vto, rbf2->gx, rbf2->gy);
270 d = Acos(DOT(vfrom, vto));
271 res = d*d;
272 d = R2ANG(rbf2->crad) - R2ANG(rbf1->crad);
273 res += d*d;
274 /* neighborhood difference */
275 res += NEIGH_FACT2 * neighborhood_dist2( rbf1->gx, rbf1->gy,
276 rbf2->gx, rbf2->gy );
277 return(res);
278 }
279
280
281 /* Compute and insert migration along directed edge (may fork child) */
282 static MIGRATION *
283 create_migration(RBFNODE *from_rbf, RBFNODE *to_rbf)
284 {
285 MIGRATION *newmig;
286 int i, j;
287 /* check if exists already */
288 for (newmig = from_rbf->ejl; newmig != NULL;
289 newmig = nextedge(from_rbf,newmig))
290 if (newmig->rbfv[1] == to_rbf)
291 return(NULL);
292 /* else allocate */
293 #ifdef DEBUG
294 fprintf(stderr, "Building path from (theta,phi) (%.1f,%.1f) ",
295 get_theta180(from_rbf->invec),
296 get_phi360(from_rbf->invec));
297 fprintf(stderr, "to (%.1f,%.1f) with %d x %d matrix\n",
298 get_theta180(to_rbf->invec),
299 get_phi360(to_rbf->invec),
300 from_rbf->nrbf, to_rbf->nrbf);
301 #endif
302 newmig = new_migration(from_rbf, to_rbf);
303 if (run_subprocess())
304 return(newmig); /* child continues */
305
306 /* compute transport plan */
307 compute_nDSFs(from_rbf, to_rbf);
308 plan_transport(newmig);
309
310 for (i = from_rbf->nrbf; i--; ) { /* normalize final matrix */
311 double nf = rbf_volume(&from_rbf->rbfa[i]);
312 if (nf <= FTINY) continue;
313 nf = from_rbf->vtotal / nf;
314 for (j = to_rbf->nrbf; j--; )
315 mtx_coef(newmig,i,j) *= nf; /* row now sums to 1.0 */
316 }
317 end_subprocess(); /* exit here if subprocess */
318 return(newmig);
319 }
320
321 /* Check if prospective vertex would create overlapping triangle */
322 static int
323 overlaps_tri(const RBFNODE *bv0, const RBFNODE *bv1, const RBFNODE *pv)
324 {
325 const MIGRATION *ej;
326 RBFNODE *vother[2];
327 int im_rev;
328 /* find shared edge in mesh */
329 for (ej = pv->ejl; ej != NULL; ej = nextedge(pv,ej)) {
330 const RBFNODE *tv = opp_rbf(pv,ej);
331 if (tv == bv0) {
332 im_rev = is_rev_tri(ej->rbfv[0]->invec,
333 ej->rbfv[1]->invec, bv1->invec);
334 break;
335 }
336 if (tv == bv1) {
337 im_rev = is_rev_tri(ej->rbfv[0]->invec,
338 ej->rbfv[1]->invec, bv0->invec);
339 break;
340 }
341 }
342 if (!get_triangles(vother, ej)) /* triangle on same side? */
343 return(0);
344 return(vother[im_rev] != NULL);
345 }
346
347 /* Find convex hull vertex to complete triangle (oriented call) */
348 static RBFNODE *
349 find_chull_vert(const RBFNODE *rbf0, const RBFNODE *rbf1)
350 {
351 FVECT vmid, vejn, vp;
352 RBFNODE *rbf, *rbfbest = NULL;
353 double dprod, area2, bestarea2 = FHUGE, bestdprod = -.5;
354
355 VSUB(vejn, rbf1->invec, rbf0->invec);
356 VADD(vmid, rbf0->invec, rbf1->invec);
357 if (normalize(vejn) == 0 || normalize(vmid) == 0)
358 return(NULL);
359 /* XXX exhaustive search */
360 /* Find triangle with minimum rotation from perpendicular */
361 for (rbf = dsf_list; rbf != NULL; rbf = rbf->next) {
362 if ((rbf == rbf0) | (rbf == rbf1))
363 continue;
364 tri_orient(vp, rbf0->invec, rbf1->invec, rbf->invec);
365 if (DOT(vp, vmid) <= FTINY)
366 continue; /* wrong orientation */
367 area2 = .25*DOT(vp,vp);
368 VSUB(vp, rbf->invec, vmid);
369 dprod = -DOT(vp, vejn);
370 VSUM(vp, vp, vejn, dprod); /* above guarantees non-zero */
371 dprod = DOT(vp, vmid) / VLEN(vp);
372 if (dprod <= bestdprod + FTINY*(1 - 2*(area2 < bestarea2)))
373 continue; /* found better already */
374 if (overlaps_tri(rbf0, rbf1, rbf))
375 continue; /* overlaps another triangle */
376 rbfbest = rbf;
377 bestdprod = dprod; /* new one to beat */
378 bestarea2 = area2;
379 }
380 return(rbfbest);
381 }
382
383 /* Create new migration edge and grow mesh recursively around it */
384 static void
385 mesh_from_edge(MIGRATION *edge)
386 {
387 MIGRATION *ej0, *ej1;
388 RBFNODE *tvert[2];
389
390 if (edge == NULL)
391 return;
392 /* triangle on either side? */
393 get_triangles(tvert, edge);
394 if (tvert[0] == NULL) { /* grow mesh on right */
395 tvert[0] = find_chull_vert(edge->rbfv[0], edge->rbfv[1]);
396 if (tvert[0] != NULL) {
397 if (tvert[0]->ord > edge->rbfv[0]->ord)
398 ej0 = create_migration(edge->rbfv[0], tvert[0]);
399 else
400 ej0 = create_migration(tvert[0], edge->rbfv[0]);
401 if (tvert[0]->ord > edge->rbfv[1]->ord)
402 ej1 = create_migration(edge->rbfv[1], tvert[0]);
403 else
404 ej1 = create_migration(tvert[0], edge->rbfv[1]);
405 mesh_from_edge(ej0);
406 mesh_from_edge(ej1);
407 return;
408 }
409 }
410 if (tvert[1] == NULL) { /* grow mesh on left */
411 tvert[1] = find_chull_vert(edge->rbfv[1], edge->rbfv[0]);
412 if (tvert[1] != NULL) {
413 if (tvert[1]->ord > edge->rbfv[0]->ord)
414 ej0 = create_migration(edge->rbfv[0], tvert[1]);
415 else
416 ej0 = create_migration(tvert[1], edge->rbfv[0]);
417 if (tvert[1]->ord > edge->rbfv[1]->ord)
418 ej1 = create_migration(edge->rbfv[1], tvert[1]);
419 else
420 ej1 = create_migration(tvert[1], edge->rbfv[1]);
421 mesh_from_edge(ej0);
422 mesh_from_edge(ej1);
423 }
424 }
425 }
426
427 /* Add normal direction if missing */
428 static void
429 check_normal_incidence(void)
430 {
431 static FVECT norm_vec = {.0, .0, 1.};
432 const int saved_nprocs = nprocs;
433 RBFNODE *near_rbf, *mir_rbf, *rbf;
434 double bestd;
435 int n;
436
437 if (dsf_list == NULL)
438 return; /* XXX should be error? */
439 near_rbf = dsf_list;
440 bestd = input_orient*near_rbf->invec[2];
441 if (single_plane_incident) { /* ordered plane incidence? */
442 if (bestd >= 1.-2.*FTINY)
443 return; /* already have normal */
444 } else {
445 switch (inp_coverage) {
446 case INP_QUAD1:
447 case INP_QUAD2:
448 case INP_QUAD3:
449 case INP_QUAD4:
450 break; /* quadrilateral symmetry? */
451 default:
452 return; /* else we can interpolate */
453 }
454 for (rbf = near_rbf->next; rbf != NULL; rbf = rbf->next) {
455 const double d = input_orient*rbf->invec[2];
456 if (d >= 1.-2.*FTINY)
457 return; /* seems we have normal */
458 if (d > bestd) {
459 near_rbf = rbf;
460 bestd = d;
461 }
462 }
463 }
464 if (mig_list != NULL) { /* need to be called first */
465 fprintf(stderr, "%s: Late call to check_normal_incidence()\n",
466 progname);
467 exit(1);
468 }
469 #ifdef DEBUG
470 fprintf(stderr, "Interpolating normal incidence by mirroring (%.1f,%.1f)\n",
471 get_theta180(near_rbf->invec), get_phi360(near_rbf->invec));
472 #endif
473 /* mirror nearest incidence */
474 n = sizeof(RBFNODE) + sizeof(RBFVAL)*(near_rbf->nrbf-1);
475 mir_rbf = (RBFNODE *)malloc(n);
476 if (mir_rbf == NULL)
477 goto memerr;
478 memcpy(mir_rbf, near_rbf, n);
479 mir_rbf->ord = near_rbf->ord - 1; /* not used, I think */
480 mir_rbf->next = NULL;
481 mir_rbf->ejl = NULL;
482 rev_rbf_symmetry(mir_rbf, MIRROR_X|MIRROR_Y);
483 nprocs = 1; /* compute migration matrix */
484 if (create_migration(mir_rbf, near_rbf) == NULL)
485 exit(1); /* XXX should never happen! */
486 norm_vec[2] = input_orient; /* interpolate normal dist. */
487 rbf = e_advect_rbf(mig_list, norm_vec, 0);
488 nprocs = saved_nprocs; /* final clean-up */
489 free(mir_rbf);
490 free(mig_list);
491 mig_list = near_rbf->ejl = NULL;
492 insert_dsf(rbf); /* insert interpolated normal */
493 return;
494 memerr:
495 fprintf(stderr, "%s: Out of memory in check_normal_incidence()\n",
496 progname);
497 exit(1);
498 }
499
500 /* Build our triangle mesh from recorded RBFs */
501 void
502 build_mesh(void)
503 {
504 double best2 = M_PI*M_PI;
505 RBFNODE *shrt_edj[2];
506 RBFNODE *rbf0, *rbf1;
507 /* average specular peak */
508 comp_bsdf_spec();
509 /* add normal if needed */
510 check_normal_incidence();
511 /* check if isotropic */
512 if (single_plane_incident) {
513 for (rbf0 = dsf_list; rbf0 != NULL; rbf0 = rbf0->next)
514 if (rbf0->next != NULL)
515 create_migration(rbf0, rbf0->next);
516 await_children(nchild);
517 return;
518 }
519 shrt_edj[0] = shrt_edj[1] = NULL; /* start w/ shortest edge */
520 for (rbf0 = dsf_list; rbf0 != NULL; rbf0 = rbf0->next)
521 for (rbf1 = rbf0->next; rbf1 != NULL; rbf1 = rbf1->next) {
522 double dist2 = 2. - 2.*DOT(rbf0->invec,rbf1->invec);
523 if (dist2 < best2) {
524 shrt_edj[0] = rbf0;
525 shrt_edj[1] = rbf1;
526 best2 = dist2;
527 }
528 }
529 if (shrt_edj[0] == NULL) {
530 fprintf(stderr, "%s: Cannot find shortest edge\n", progname);
531 exit(1);
532 }
533 /* build mesh from this edge */
534 if (shrt_edj[0]->ord < shrt_edj[1]->ord)
535 mesh_from_edge(create_migration(shrt_edj[0], shrt_edj[1]));
536 else
537 mesh_from_edge(create_migration(shrt_edj[1], shrt_edj[0]));
538 /* complete migrations */
539 await_children(nchild);
540 }