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root/radiance/ray/src/cv/bsdfmesh.c
Revision: 2.18
Committed: Thu Mar 6 00:40:37 2014 UTC (10 years, 1 month ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 2.17: +2 -3 lines
Log Message:
Switched to calling Acos() wherever appropriate

File Contents

# User Rev Content
1 greg 2.1 #ifndef lint
2 greg 2.18 static const char RCSid[] = "$Id: bsdfmesh.c,v 2.17 2014/03/05 22:47:16 greg Exp $";
3 greg 2.1 #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     /* number of processes to run */
22     int nprocs = 1;
23     /* number of children (-1 in child) */
24     static int nchild = 0;
25    
26 greg 2.3 typedef struct {
27     int nrows, ncols; /* array size (matches migration) */
28     float *price; /* migration prices */
29     short *sord; /* sort for each row, low to high */
30 greg 2.10 float *prow; /* current price row */
31 greg 2.3 } PRICEMAT; /* sorted pricing matrix */
32    
33     #define pricerow(p,i) ((p)->price + (i)*(p)->ncols)
34     #define psortrow(p,i) ((p)->sord + (i)*(p)->ncols)
35    
36 greg 2.2 /* Create a new migration holder (sharing memory for multiprocessing) */
37     static MIGRATION *
38     new_migration(RBFNODE *from_rbf, RBFNODE *to_rbf)
39     {
40     size_t memlen = sizeof(MIGRATION) +
41     sizeof(float)*(from_rbf->nrbf*to_rbf->nrbf - 1);
42     MIGRATION *newmig;
43     #ifdef _WIN32
44     if (nprocs > 1)
45     fprintf(stderr, "%s: warning - multiprocessing not supported\n",
46     progname);
47     nprocs = 1;
48     newmig = (MIGRATION *)malloc(memlen);
49     #else
50     if (nprocs <= 1) { /* single process? */
51     newmig = (MIGRATION *)malloc(memlen);
52     } else { /* else need to share memory */
53     newmig = (MIGRATION *)mmap(NULL, memlen, PROT_READ|PROT_WRITE,
54     MAP_ANON|MAP_SHARED, -1, 0);
55     if ((void *)newmig == MAP_FAILED)
56     newmig = NULL;
57     }
58     #endif
59     if (newmig == NULL) {
60     fprintf(stderr, "%s: cannot allocate new migration\n", progname);
61     exit(1);
62     }
63     newmig->rbfv[0] = from_rbf;
64     newmig->rbfv[1] = to_rbf;
65     /* insert in edge lists */
66     newmig->enxt[0] = from_rbf->ejl;
67     from_rbf->ejl = newmig;
68     newmig->enxt[1] = to_rbf->ejl;
69     to_rbf->ejl = newmig;
70     newmig->next = mig_list; /* push onto global list */
71     return(mig_list = newmig);
72     }
73    
74     #ifdef _WIN32
75     #define await_children(n) (void)(n)
76     #define run_subprocess() 0
77     #define end_subprocess() (void)0
78     #else
79    
80     /* Wait for the specified number of child processes to complete */
81     static void
82     await_children(int n)
83     {
84     int exit_status = 0;
85    
86     if (n > nchild)
87     n = nchild;
88     while (n-- > 0) {
89     int status;
90     if (wait(&status) < 0) {
91     fprintf(stderr, "%s: missing child(ren)!\n", progname);
92     nchild = 0;
93     break;
94     }
95     --nchild;
96     if (status) { /* something wrong */
97     if ((status = WEXITSTATUS(status)))
98     exit_status = status;
99     else
100     exit_status += !exit_status;
101     fprintf(stderr, "%s: subprocess died\n", progname);
102     n = nchild; /* wait for the rest */
103     }
104     }
105     if (exit_status)
106     exit(exit_status);
107     }
108    
109     /* Start child process if multiprocessing selected */
110     static pid_t
111     run_subprocess(void)
112     {
113     int status;
114     pid_t pid;
115    
116     if (nprocs <= 1) /* any children requested? */
117     return(0);
118     await_children(nchild + 1 - nprocs); /* free up child process */
119     if ((pid = fork())) {
120     if (pid < 0) {
121     fprintf(stderr, "%s: cannot fork subprocess\n",
122     progname);
123 greg 2.6 await_children(nchild);
124 greg 2.2 exit(1);
125     }
126     ++nchild; /* subprocess started */
127     return(pid);
128     }
129     nchild = -1;
130     return(0); /* put child to work */
131     }
132    
133     /* If we are in subprocess, call exit */
134     #define end_subprocess() if (nchild < 0) _exit(0); else
135    
136     #endif /* ! _WIN32 */
137    
138 greg 2.3 /* Comparison routine needed for sorting price row */
139     static int
140     msrt_cmp(void *b, const void *p1, const void *p2)
141     {
142     PRICEMAT *pm = (PRICEMAT *)b;
143 greg 2.10 float c1 = pm->prow[*(const short *)p1];
144     float c2 = pm->prow[*(const short *)p2];
145 greg 2.3
146     if (c1 > c2) return(1);
147     if (c1 < c2) return(-1);
148     return(0);
149     }
150    
151 greg 2.1 /* Compute (and allocate) migration price matrix for optimization */
152 greg 2.3 static void
153     price_routes(PRICEMAT *pm, const RBFNODE *from_rbf, const RBFNODE *to_rbf)
154 greg 2.1 {
155     FVECT *vto = (FVECT *)malloc(sizeof(FVECT) * to_rbf->nrbf);
156     int i, j;
157    
158 greg 2.3 pm->nrows = from_rbf->nrbf;
159     pm->ncols = to_rbf->nrbf;
160     pm->price = (float *)malloc(sizeof(float) * pm->nrows*pm->ncols);
161     pm->sord = (short *)malloc(sizeof(short) * pm->nrows*pm->ncols);
162    
163     if ((pm->price == NULL) | (pm->sord == NULL) | (vto == NULL)) {
164 greg 2.1 fprintf(stderr, "%s: Out of memory in migration_costs()\n",
165     progname);
166     exit(1);
167     }
168     for (j = to_rbf->nrbf; j--; ) /* save repetitive ops. */
169     ovec_from_pos(vto[j], to_rbf->rbfa[j].gx, to_rbf->rbfa[j].gy);
170    
171     for (i = from_rbf->nrbf; i--; ) {
172     const double from_ang = R2ANG(from_rbf->rbfa[i].crad);
173     FVECT vfrom;
174 greg 2.10 short *srow;
175 greg 2.1 ovec_from_pos(vfrom, from_rbf->rbfa[i].gx, from_rbf->rbfa[i].gy);
176 greg 2.10 pm->prow = pricerow(pm,i);
177     srow = psortrow(pm,i);
178 greg 2.3 for (j = to_rbf->nrbf; j--; ) {
179 greg 2.13 double d; /* quadratic cost function */
180 greg 2.18 d = Acos(DOT(vfrom, vto[j]));
181 greg 2.13 pm->prow[j] = d*d;
182     d = R2ANG(to_rbf->rbfa[j].crad) - from_ang;
183     pm->prow[j] += d*d;
184 greg 2.10 srow[j] = j;
185 greg 2.3 }
186 greg 2.10 qsort_r(srow, pm->ncols, sizeof(short), pm, &msrt_cmp);
187 greg 2.1 }
188     free(vto);
189     }
190    
191 greg 2.3 /* Free price matrix */
192     static void
193     free_routes(PRICEMAT *pm)
194 greg 2.1 {
195 greg 2.3 free(pm->price); pm->price = NULL;
196     free(pm->sord); pm->sord = NULL;
197 greg 2.1 }
198    
199     /* Compute minimum (optimistic) cost for moving the given source material */
200     static double
201 greg 2.3 min_cost(double amt2move, const double *avail, const PRICEMAT *pm, int s)
202 greg 2.1 {
203 greg 2.11 const short *srow = psortrow(pm,s);
204     const float *prow = pricerow(pm,s);
205 greg 2.1 double total_cost = 0;
206 greg 2.3 int j;
207 greg 2.1 /* move cheapest first */
208 greg 2.11 for (j = 0; (j < pm->ncols) & (amt2move > FTINY); j++) {
209     int d = srow[j];
210 greg 2.1 double amt = (amt2move < avail[d]) ? amt2move : avail[d];
211    
212 greg 2.11 total_cost += amt * prow[d];
213 greg 2.1 amt2move -= amt;
214     }
215     return(total_cost);
216     }
217    
218 greg 2.17 typedef struct {
219     short s, d; /* source and destination */
220     float dc; /* discount to push inventory */
221     } ROWSENT; /* row sort entry */
222    
223     /* Compare entries by discounted moving price */
224 greg 2.11 static int
225     rmovcmp(void *b, const void *p1, const void *p2)
226     {
227     PRICEMAT *pm = (PRICEMAT *)b;
228 greg 2.17 const ROWSENT *re1 = (const ROWSENT *)p1;
229     const ROWSENT *re2 = (const ROWSENT *)p2;
230     double price_diff;
231    
232     if (re1->d < 0) return(re2->d >= 0);
233     if (re2->d < 0) return(-1);
234     price_diff = re1->dc*pricerow(pm,re1->s)[re1->d] -
235     re2->dc*pricerow(pm,re2->s)[re2->d];
236 greg 2.11 if (price_diff > 0) return(1);
237     if (price_diff < 0) return(-1);
238     return(0);
239     }
240    
241     /* Take a step in migration by choosing reasonable bucket to transfer */
242 greg 2.1 static double
243 greg 2.11 migration_step(MIGRATION *mig, double *src_rem, double *dst_rem, PRICEMAT *pm)
244 greg 2.1 {
245 greg 2.11 const int max2check = 100;
246 greg 2.4 const double maxamt = 1./(double)pm->ncols;
247 greg 2.12 const double minamt = maxamt*1e-4;
248 greg 2.5 double *src_cost;
249 greg 2.17 ROWSENT *rord;
250 greg 2.1 struct {
251     int s, d; /* source and destination */
252 greg 2.17 double price; /* cost per amount moved */
253 greg 2.1 double amt; /* amount we can move */
254     } cur, best;
255 greg 2.11 int r2check, i, ri;
256     /*
257     * Check cheapest available routes only -- a higher adjusted
258     * destination price implies that another source is closer, so
259     * we can hold off considering more expensive options until
260     * some other (hopefully better) moves have been made.
261 greg 2.17 * A discount based on source remaining is supposed to prioritize
262     * movement from large lobes, but it doesn't seem to do much,
263     * so we have it set to 1.0 at the moment.
264 greg 2.11 */
265 greg 2.17 #define discount(qr) 1.0
266 greg 2.11 /* most promising row order */
267 greg 2.17 rord = (ROWSENT *)malloc(sizeof(ROWSENT)*pm->nrows);
268 greg 2.11 if (rord == NULL)
269     goto memerr;
270     for (ri = pm->nrows; ri--; ) {
271 greg 2.17 rord[ri].s = ri;
272     rord[ri].d = -1;
273     rord[ri].dc = 1.f;
274 greg 2.11 if (src_rem[ri] <= minamt) /* enough source material? */
275     continue;
276     for (i = 0; i < pm->ncols; i++)
277 greg 2.17 if (dst_rem[ rord[ri].d = psortrow(pm,ri)[i] ] > minamt)
278 greg 2.11 break;
279     if (i >= pm->ncols) { /* moved all we can? */
280     free(rord);
281     return(.0);
282     }
283 greg 2.17 rord[ri].dc = discount(src_rem[ri]);
284 greg 2.11 }
285     if (pm->nrows > max2check) /* sort if too many sources */
286 greg 2.17 qsort_r(rord, pm->nrows, sizeof(ROWSENT), pm, &rmovcmp);
287 greg 2.5 /* allocate cost array */
288     src_cost = (double *)malloc(sizeof(double)*pm->nrows);
289 greg 2.11 if (src_cost == NULL)
290     goto memerr;
291 greg 2.3 for (i = pm->nrows; i--; ) /* starting costs for diff. */
292     src_cost[i] = min_cost(src_rem[i], dst_rem, pm, i);
293 greg 2.1 /* find best source & dest. */
294     best.s = best.d = -1; best.price = FHUGE; best.amt = 0;
295 greg 2.11 if ((r2check = pm->nrows) > max2check)
296     r2check = max2check; /* put a limit on search */
297     for (ri = 0; ri < r2check; ri++) { /* check each source row */
298 greg 2.1 double cost_others = 0;
299 greg 2.17 cur.s = rord[ri].s;
300     if ((cur.d = rord[ri].d) < 0 ||
301     rord[ri].dc*pricerow(pm,cur.s)[cur.d] >= best.price) {
302 greg 2.11 if (pm->nrows > max2check) break; /* sorted end */
303     continue; /* else skip this one */
304     }
305 greg 2.1 cur.amt = (src_rem[cur.s] < dst_rem[cur.d]) ?
306     src_rem[cur.s] : dst_rem[cur.d];
307 greg 2.11 /* don't just leave smidgen */
308     if (cur.amt > maxamt*1.02) cur.amt = maxamt;
309     dst_rem[cur.d] -= cur.amt; /* add up opportunity costs */
310 greg 2.3 for (i = pm->nrows; i--; )
311 greg 2.1 if (i != cur.s)
312 greg 2.11 cost_others += min_cost(src_rem[i], dst_rem, pm, i)
313 greg 2.1 - src_cost[i];
314     dst_rem[cur.d] += cur.amt; /* undo trial move */
315 greg 2.17 /* discount effective price */
316     cur.price = ( pricerow(pm,cur.s)[cur.d] + cost_others/cur.amt ) *
317     rord[ri].dc;
318 greg 2.1 if (cur.price < best.price) /* are we better than best? */
319 greg 2.11 best = cur;
320 greg 2.1 }
321 greg 2.11 free(src_cost); /* clean up */
322     free(rord);
323 greg 2.5 if ((best.s < 0) | (best.d < 0)) /* nothing left to move? */
324 greg 2.1 return(.0);
325 greg 2.5 /* else make the actual move */
326 greg 2.2 mtx_coef(mig,best.s,best.d) += best.amt;
327 greg 2.1 src_rem[best.s] -= best.amt;
328     dst_rem[best.d] -= best.amt;
329     return(best.amt);
330 greg 2.11 memerr:
331     fprintf(stderr, "%s: Out of memory in migration_step()\n", progname);
332     exit(1);
333 greg 2.17 #undef discount
334 greg 2.1 }
335    
336     /* Compute and insert migration along directed edge (may fork child) */
337     static MIGRATION *
338     create_migration(RBFNODE *from_rbf, RBFNODE *to_rbf)
339     {
340 greg 2.2 const double end_thresh = 5e-6;
341 greg 2.3 PRICEMAT pmtx;
342 greg 2.1 MIGRATION *newmig;
343     double *src_rem, *dst_rem;
344     double total_rem = 1., move_amt;
345 greg 2.6 int i, j;
346 greg 2.1 /* check if exists already */
347     for (newmig = from_rbf->ejl; newmig != NULL;
348     newmig = nextedge(from_rbf,newmig))
349     if (newmig->rbfv[1] == to_rbf)
350     return(NULL);
351     /* else allocate */
352 greg 2.7 #ifdef DEBUG
353 greg 2.14 fprintf(stderr, "Building path from (theta,phi) (%.1f,%.1f) ",
354 greg 2.7 get_theta180(from_rbf->invec),
355     get_phi360(from_rbf->invec));
356 greg 2.14 fprintf(stderr, "to (%.1f,%.1f) with %d x %d matrix\n",
357 greg 2.7 get_theta180(to_rbf->invec),
358     get_phi360(to_rbf->invec),
359     from_rbf->nrbf, to_rbf->nrbf);
360     #endif
361 greg 2.1 newmig = new_migration(from_rbf, to_rbf);
362     if (run_subprocess())
363     return(newmig); /* child continues */
364 greg 2.3 price_routes(&pmtx, from_rbf, to_rbf);
365 greg 2.1 src_rem = (double *)malloc(sizeof(double)*from_rbf->nrbf);
366     dst_rem = (double *)malloc(sizeof(double)*to_rbf->nrbf);
367     if ((src_rem == NULL) | (dst_rem == NULL)) {
368     fprintf(stderr, "%s: Out of memory in create_migration()\n",
369     progname);
370     exit(1);
371     }
372     /* starting quantities */
373     memset(newmig->mtx, 0, sizeof(float)*from_rbf->nrbf*to_rbf->nrbf);
374     for (i = from_rbf->nrbf; i--; )
375     src_rem[i] = rbf_volume(&from_rbf->rbfa[i]) / from_rbf->vtotal;
376 greg 2.6 for (j = to_rbf->nrbf; j--; )
377     dst_rem[j] = rbf_volume(&to_rbf->rbfa[j]) / to_rbf->vtotal;
378    
379 greg 2.1 do { /* move a bit at a time */
380 greg 2.3 move_amt = migration_step(newmig, src_rem, dst_rem, &pmtx);
381 greg 2.1 total_rem -= move_amt;
382 greg 2.2 } while ((total_rem > end_thresh) & (move_amt > 0));
383 greg 2.6
384 greg 2.1 for (i = from_rbf->nrbf; i--; ) { /* normalize final matrix */
385 greg 2.6 double nf = rbf_volume(&from_rbf->rbfa[i]);
386 greg 2.1 if (nf <= FTINY) continue;
387     nf = from_rbf->vtotal / nf;
388     for (j = to_rbf->nrbf; j--; )
389 greg 2.6 mtx_coef(newmig,i,j) *= nf; /* row now sums to 1.0 */
390 greg 2.1 }
391     end_subprocess(); /* exit here if subprocess */
392 greg 2.3 free_routes(&pmtx); /* free working arrays */
393 greg 2.1 free(src_rem);
394     free(dst_rem);
395     return(newmig);
396     }
397    
398     /* Check if prospective vertex would create overlapping triangle */
399     static int
400     overlaps_tri(const RBFNODE *bv0, const RBFNODE *bv1, const RBFNODE *pv)
401     {
402     const MIGRATION *ej;
403     RBFNODE *vother[2];
404     int im_rev;
405     /* find shared edge in mesh */
406     for (ej = pv->ejl; ej != NULL; ej = nextedge(pv,ej)) {
407     const RBFNODE *tv = opp_rbf(pv,ej);
408     if (tv == bv0) {
409     im_rev = is_rev_tri(ej->rbfv[0]->invec,
410     ej->rbfv[1]->invec, bv1->invec);
411     break;
412     }
413     if (tv == bv1) {
414     im_rev = is_rev_tri(ej->rbfv[0]->invec,
415     ej->rbfv[1]->invec, bv0->invec);
416     break;
417     }
418     }
419     if (!get_triangles(vother, ej)) /* triangle on same side? */
420     return(0);
421     return(vother[im_rev] != NULL);
422     }
423    
424 greg 2.14 /* Find convex hull vertex to complete triangle (oriented call) */
425 greg 2.1 static RBFNODE *
426     find_chull_vert(const RBFNODE *rbf0, const RBFNODE *rbf1)
427     {
428     FVECT vmid, vejn, vp;
429     RBFNODE *rbf, *rbfbest = NULL;
430     double dprod, area2, bestarea2 = FHUGE, bestdprod = -.5;
431    
432     VSUB(vejn, rbf1->invec, rbf0->invec);
433     VADD(vmid, rbf0->invec, rbf1->invec);
434     if (normalize(vejn) == 0 || normalize(vmid) == 0)
435     return(NULL);
436     /* XXX exhaustive search */
437     /* Find triangle with minimum rotation from perpendicular */
438     for (rbf = dsf_list; rbf != NULL; rbf = rbf->next) {
439     if ((rbf == rbf0) | (rbf == rbf1))
440     continue;
441     tri_orient(vp, rbf0->invec, rbf1->invec, rbf->invec);
442     if (DOT(vp, vmid) <= FTINY)
443     continue; /* wrong orientation */
444     area2 = .25*DOT(vp,vp);
445 greg 2.14 VSUB(vp, rbf->invec, vmid);
446 greg 2.1 dprod = -DOT(vp, vejn);
447     VSUM(vp, vp, vejn, dprod); /* above guarantees non-zero */
448     dprod = DOT(vp, vmid) / VLEN(vp);
449     if (dprod <= bestdprod + FTINY*(1 - 2*(area2 < bestarea2)))
450     continue; /* found better already */
451     if (overlaps_tri(rbf0, rbf1, rbf))
452     continue; /* overlaps another triangle */
453     rbfbest = rbf;
454     bestdprod = dprod; /* new one to beat */
455     bestarea2 = area2;
456     }
457     return(rbfbest);
458     }
459    
460     /* Create new migration edge and grow mesh recursively around it */
461     static void
462     mesh_from_edge(MIGRATION *edge)
463     {
464     MIGRATION *ej0, *ej1;
465     RBFNODE *tvert[2];
466    
467     if (edge == NULL)
468     return;
469     /* triangle on either side? */
470     get_triangles(tvert, edge);
471     if (tvert[0] == NULL) { /* grow mesh on right */
472     tvert[0] = find_chull_vert(edge->rbfv[0], edge->rbfv[1]);
473     if (tvert[0] != NULL) {
474     if (tvert[0]->ord > edge->rbfv[0]->ord)
475     ej0 = create_migration(edge->rbfv[0], tvert[0]);
476     else
477     ej0 = create_migration(tvert[0], edge->rbfv[0]);
478     if (tvert[0]->ord > edge->rbfv[1]->ord)
479     ej1 = create_migration(edge->rbfv[1], tvert[0]);
480     else
481     ej1 = create_migration(tvert[0], edge->rbfv[1]);
482     mesh_from_edge(ej0);
483     mesh_from_edge(ej1);
484     }
485     } else if (tvert[1] == NULL) { /* grow mesh on left */
486     tvert[1] = find_chull_vert(edge->rbfv[1], edge->rbfv[0]);
487     if (tvert[1] != NULL) {
488     if (tvert[1]->ord > edge->rbfv[0]->ord)
489     ej0 = create_migration(edge->rbfv[0], tvert[1]);
490     else
491     ej0 = create_migration(tvert[1], edge->rbfv[0]);
492     if (tvert[1]->ord > edge->rbfv[1]->ord)
493     ej1 = create_migration(edge->rbfv[1], tvert[1]);
494     else
495     ej1 = create_migration(tvert[1], edge->rbfv[1]);
496     mesh_from_edge(ej0);
497     mesh_from_edge(ej1);
498     }
499     }
500     }
501 greg 2.15
502     /* Add normal direction if missing */
503     static void
504     check_normal_incidence(void)
505     {
506 greg 2.16 static const FVECT norm_vec = {.0, .0, 1.};
507     const int saved_nprocs = nprocs;
508     RBFNODE *near_rbf, *mir_rbf, *rbf;
509     double bestd;
510     int n;
511 greg 2.15
512     if (dsf_list == NULL)
513     return; /* XXX should be error? */
514     near_rbf = dsf_list;
515     bestd = input_orient*near_rbf->invec[2];
516     if (single_plane_incident) { /* ordered plane incidence? */
517     if (bestd >= 1.-2.*FTINY)
518     return; /* already have normal */
519     } else {
520     switch (inp_coverage) {
521     case INP_QUAD1:
522     case INP_QUAD2:
523     case INP_QUAD3:
524     case INP_QUAD4:
525     break; /* quadrilateral symmetry? */
526     default:
527     return; /* else we can interpolate */
528     }
529     for (rbf = near_rbf->next; rbf != NULL; rbf = rbf->next) {
530     const double d = input_orient*rbf->invec[2];
531     if (d >= 1.-2.*FTINY)
532     return; /* seems we have normal */
533     if (d > bestd) {
534     near_rbf = rbf;
535     bestd = d;
536     }
537     }
538     }
539     if (mig_list != NULL) { /* need to be called first */
540     fprintf(stderr, "%s: Late call to check_normal_incidence()\n",
541     progname);
542     exit(1);
543     }
544     #ifdef DEBUG
545     fprintf(stderr, "Interpolating normal incidence by mirroring (%.1f,%.1f)\n",
546     get_theta180(near_rbf->invec), get_phi360(near_rbf->invec));
547     #endif
548     /* mirror nearest incidence */
549     n = sizeof(RBFNODE) + sizeof(RBFVAL)*(near_rbf->nrbf-1);
550     mir_rbf = (RBFNODE *)malloc(n);
551     if (mir_rbf == NULL)
552     goto memerr;
553     memcpy(mir_rbf, near_rbf, n);
554     mir_rbf->ord = near_rbf->ord - 1; /* not used, I think */
555     mir_rbf->next = NULL;
556     rev_rbf_symmetry(mir_rbf, MIRROR_X|MIRROR_Y);
557     nprocs = 1; /* compute migration matrix */
558     if (mig_list != create_migration(mir_rbf, near_rbf))
559     exit(1); /* XXX should never happen! */
560 greg 2.16 /* interpolate normal dist. */
561     rbf = e_advect_rbf(mig_list, norm_vec, 2*near_rbf->nrbf);
562 greg 2.15 nprocs = saved_nprocs; /* final clean-up */
563     free(mir_rbf);
564     free(mig_list);
565     mig_list = near_rbf->ejl = NULL;
566     insert_dsf(rbf); /* insert interpolated normal */
567     return;
568     memerr:
569     fprintf(stderr, "%s: Out of memory in check_normal_incidence()\n",
570     progname);
571     exit(1);
572     }
573 greg 2.1
574     /* Build our triangle mesh from recorded RBFs */
575     void
576     build_mesh(void)
577     {
578     double best2 = M_PI*M_PI;
579     RBFNODE *shrt_edj[2];
580     RBFNODE *rbf0, *rbf1;
581 greg 2.15 /* add normal if needed */
582     check_normal_incidence();
583 greg 2.1 /* check if isotropic */
584     if (single_plane_incident) {
585     for (rbf0 = dsf_list; rbf0 != NULL; rbf0 = rbf0->next)
586     if (rbf0->next != NULL)
587     create_migration(rbf0, rbf0->next);
588     await_children(nchild);
589     return;
590     }
591     shrt_edj[0] = shrt_edj[1] = NULL; /* start w/ shortest edge */
592     for (rbf0 = dsf_list; rbf0 != NULL; rbf0 = rbf0->next)
593     for (rbf1 = rbf0->next; rbf1 != NULL; rbf1 = rbf1->next) {
594     double dist2 = 2. - 2.*DOT(rbf0->invec,rbf1->invec);
595     if (dist2 < best2) {
596     shrt_edj[0] = rbf0;
597     shrt_edj[1] = rbf1;
598     best2 = dist2;
599     }
600     }
601     if (shrt_edj[0] == NULL) {
602     fprintf(stderr, "%s: Cannot find shortest edge\n", progname);
603     exit(1);
604     }
605     /* build mesh from this edge */
606     if (shrt_edj[0]->ord < shrt_edj[1]->ord)
607     mesh_from_edge(create_migration(shrt_edj[0], shrt_edj[1]));
608     else
609     mesh_from_edge(create_migration(shrt_edj[1], shrt_edj[0]));
610     /* complete migrations */
611     await_children(nchild);
612     }