ViewVC Help
View File | Revision Log | Show Annotations | Download File | Root Listing
root/radiance/ray/src/cv/bsdfmesh.c
Revision: 2.37
Committed: Sun Mar 6 01:13:17 2016 UTC (8 years, 2 months ago) by schorsch
Content type: text/plain
Branch: MAIN
Changes since 2.36: +4 -4 lines
Log Message:
Prepare for SCons build on Win32 and Win64

File Contents

# User Rev Content
1 greg 2.1 #ifndef lint
2 schorsch 2.37 static const char RCSid[] = "$Id: bsdfmesh.c,v 2.36 2016/01/30 17:34:00 greg Exp $";
3 greg 2.1 #endif
4     /*
5     * Create BSDF advection mesh from radial basis functions.
6     *
7     * G. Ward
8     */
9    
10 schorsch 2.37 #if !defined(_WIN32) && !defined(_WIN64)
11 greg 2.1 #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 greg 2.19
22     #ifndef NEIGH_FACT2
23 greg 2.21 #define NEIGH_FACT2 0.1 /* empirical neighborhood distance weight */
24 greg 2.19 #endif
25 greg 2.1 /* number of processes to run */
26     int nprocs = 1;
27     /* number of children (-1 in child) */
28     static int nchild = 0;
29    
30 greg 2.30 /* 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 greg 2.33 sum += eval_rbfrep(rbf, tvec) * COSF(tvec[2]);
55 greg 2.30 ++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 greg 2.33 const double DSFtarget = 0.60653066 * eval_rbfrep(rbf,outvec) *
68     COSF(outvec[2]);
69 greg 2.30 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 greg 2.32 /* Newton's method (sort of) */
76     do {
77 greg 2.30 double test_rad = interp_rad;
78 greg 2.32 double DSFtest;
79     if (test_rad >= outside_rad)
80     return(test_rad);
81     if (test_rad <= inside_rad)
82     return(test_rad*(test_rad>0));
83     DSFtest = eval_DSFsurround(rbf, outvec, test_rad);
84     if (DSFtest > DSFtarget) {
85 greg 2.30 inside_rad = test_rad;
86     DSFinside = DSFtest;
87     } else {
88     outside_rad = test_rad;
89     DSFoutside = DSFtest;
90     }
91 greg 2.32 if (DSFoutside >= DSFinside)
92     return(test_rad);
93     } while (outside_rad-inside_rad > rad_epsilon);
94 greg 2.30 return(interp_rad);
95     #undef interp_rad
96     }
97    
98 greg 2.35 static int
99     dbl_cmp(const void *p1, const void *p2)
100     {
101     double d1 = *(const double *)p1;
102     double d2 = *(const double *)p2;
103    
104     if (d1 > d2) return(1);
105     if (d1 < d2) return(-1);
106     return(0);
107     }
108    
109 greg 2.36 /* Conservative estimate of average BSDF value from current DSF's */
110 greg 2.30 static void
111     comp_bsdf_spec(void)
112     {
113 greg 2.35 double vmod_sum = 0;
114 greg 2.30 double rad_sum = 0;
115     int n = 0;
116 greg 2.35 double *cost_list = NULL;
117     double max_cost = 1.;
118 greg 2.30 RBFNODE *rbf;
119     FVECT sdv;
120 greg 2.36 /* sort by incident altitude */
121 greg 2.35 for (rbf = dsf_list; rbf != NULL; rbf = rbf->next)
122     n++;
123     if (n >= 10)
124     cost_list = (double *)malloc(sizeof(double)*n);
125     if (cost_list == NULL) {
126     bsdf_spec_val = 0;
127 greg 2.31 bsdf_spec_rad = 0;
128 greg 2.30 return;
129     }
130 greg 2.35 n = 0;
131     for (rbf = dsf_list; rbf != NULL; rbf = rbf->next)
132     cost_list[n++] = rbf->invec[2]*input_orient;
133     qsort(cost_list, n, sizeof(double), dbl_cmp);
134 greg 2.36 max_cost = cost_list[(n+3)/4]; /* accept 25% nearest grazing */
135 greg 2.35 free(cost_list);
136     n = 0;
137 greg 2.30 for (rbf = dsf_list; rbf != NULL; rbf = rbf->next) {
138 greg 2.35 double this_rad, cosfact, vest;
139     if (rbf->invec[2]*input_orient > max_cost)
140     continue;
141 greg 2.30 sdv[0] = -rbf->invec[0];
142     sdv[1] = -rbf->invec[1];
143     sdv[2] = rbf->invec[2]*(2*(input_orient==output_orient) - 1);
144 greg 2.36 cosfact = COSF(sdv[2]);
145 greg 2.35 this_rad = est_DSFrad(rbf, sdv);
146     vest = eval_rbfrep(rbf, sdv) * cosfact *
147 greg 2.36 (2.*M_PI) * this_rad*this_rad;
148     if (vest > rbf->vtotal) /* don't over-estimate energy */
149 greg 2.35 vest = rbf->vtotal;
150 greg 2.36 vmod_sum += vest / cosfact; /* remove cosine factor */
151 greg 2.35 rad_sum += this_rad;
152 greg 2.30 ++n;
153     }
154 greg 2.31 bsdf_spec_rad = rad_sum/(double)n;
155 greg 2.35 bsdf_spec_val = vmod_sum/(2.*M_PI*n*bsdf_spec_rad*bsdf_spec_rad);
156 greg 2.30 }
157    
158 greg 2.2 /* Create a new migration holder (sharing memory for multiprocessing) */
159     static MIGRATION *
160     new_migration(RBFNODE *from_rbf, RBFNODE *to_rbf)
161     {
162     size_t memlen = sizeof(MIGRATION) +
163     sizeof(float)*(from_rbf->nrbf*to_rbf->nrbf - 1);
164     MIGRATION *newmig;
165 schorsch 2.37 #if defined(_WIN32) || defined(_WIN64)
166 greg 2.2 if (nprocs > 1)
167     fprintf(stderr, "%s: warning - multiprocessing not supported\n",
168     progname);
169     nprocs = 1;
170     newmig = (MIGRATION *)malloc(memlen);
171     #else
172     if (nprocs <= 1) { /* single process? */
173     newmig = (MIGRATION *)malloc(memlen);
174     } else { /* else need to share memory */
175     newmig = (MIGRATION *)mmap(NULL, memlen, PROT_READ|PROT_WRITE,
176     MAP_ANON|MAP_SHARED, -1, 0);
177     if ((void *)newmig == MAP_FAILED)
178     newmig = NULL;
179     }
180     #endif
181     if (newmig == NULL) {
182     fprintf(stderr, "%s: cannot allocate new migration\n", progname);
183     exit(1);
184     }
185     newmig->rbfv[0] = from_rbf;
186     newmig->rbfv[1] = to_rbf;
187     /* insert in edge lists */
188     newmig->enxt[0] = from_rbf->ejl;
189     from_rbf->ejl = newmig;
190     newmig->enxt[1] = to_rbf->ejl;
191     to_rbf->ejl = newmig;
192     newmig->next = mig_list; /* push onto global list */
193     return(mig_list = newmig);
194     }
195    
196 schorsch 2.37 #if defined(_WIN32) || defined(_WIN64)
197 greg 2.2 #define await_children(n) (void)(n)
198     #define run_subprocess() 0
199     #define end_subprocess() (void)0
200     #else
201    
202     /* Wait for the specified number of child processes to complete */
203     static void
204     await_children(int n)
205     {
206     int exit_status = 0;
207    
208     if (n > nchild)
209     n = nchild;
210     while (n-- > 0) {
211     int status;
212     if (wait(&status) < 0) {
213     fprintf(stderr, "%s: missing child(ren)!\n", progname);
214     nchild = 0;
215     break;
216     }
217     --nchild;
218     if (status) { /* something wrong */
219     if ((status = WEXITSTATUS(status)))
220     exit_status = status;
221     else
222     exit_status += !exit_status;
223     fprintf(stderr, "%s: subprocess died\n", progname);
224     n = nchild; /* wait for the rest */
225     }
226     }
227     if (exit_status)
228     exit(exit_status);
229     }
230    
231     /* Start child process if multiprocessing selected */
232     static pid_t
233     run_subprocess(void)
234     {
235     int status;
236     pid_t pid;
237    
238     if (nprocs <= 1) /* any children requested? */
239     return(0);
240     await_children(nchild + 1 - nprocs); /* free up child process */
241     if ((pid = fork())) {
242     if (pid < 0) {
243     fprintf(stderr, "%s: cannot fork subprocess\n",
244     progname);
245 greg 2.6 await_children(nchild);
246 greg 2.2 exit(1);
247     }
248     ++nchild; /* subprocess started */
249     return(pid);
250     }
251     nchild = -1;
252     return(0); /* put child to work */
253     }
254    
255     /* If we are in subprocess, call exit */
256     #define end_subprocess() if (nchild < 0) _exit(0); else
257    
258     #endif /* ! _WIN32 */
259    
260 greg 2.19 /* Compute normalized distribution scattering functions for comparison */
261     static void
262     compute_nDSFs(const RBFNODE *rbf0, const RBFNODE *rbf1)
263     {
264     const double nf0 = (GRIDRES*GRIDRES) / rbf0->vtotal;
265     const double nf1 = (GRIDRES*GRIDRES) / rbf1->vtotal;
266     int x, y;
267     FVECT dv;
268    
269     for (x = GRIDRES; x--; )
270     for (y = GRIDRES; y--; ) {
271 greg 2.20 ovec_from_pos(dv, x, y); /* cube root (brightness) */
272     dsf_grid[x][y].val[0] = pow(nf0*eval_rbfrep(rbf0, dv), .3333);
273     dsf_grid[x][y].val[1] = pow(nf1*eval_rbfrep(rbf1, dv), .3333);
274 greg 2.19 }
275     }
276    
277     /* Compute neighborhood distance-squared (dissimilarity) */
278     static double
279     neighborhood_dist2(int x0, int y0, int x1, int y1)
280     {
281     int rad = GRIDRES>>5;
282     double sum2 = 0.;
283     double d;
284     int p[4];
285     int i, j;
286     /* check radius */
287     p[0] = x0; p[1] = y0; p[2] = x1; p[3] = y1;
288     for (i = 4; i--; ) {
289     if (p[i] < rad) rad = p[i];
290     if (GRIDRES-1-p[i] < rad) rad = GRIDRES-1-p[i];
291     }
292     for (i = -rad; i <= rad; i++)
293     for (j = -rad; j <= rad; j++) {
294     d = dsf_grid[x0+i][y0+j].val[0] -
295     dsf_grid[x1+i][y1+j].val[1];
296     sum2 += d*d;
297     }
298     return(sum2 / (4*rad*(rad+1) + 1));
299     }
300    
301 greg 2.27 /* Compute distance between two RBF lobes */
302     double
303     lobe_distance(RBFVAL *rbf1, RBFVAL *rbf2)
304     {
305     FVECT vfrom, vto;
306     double d, res;
307     /* quadratic cost function */
308     ovec_from_pos(vfrom, rbf1->gx, rbf1->gy);
309     ovec_from_pos(vto, rbf2->gx, rbf2->gy);
310     d = Acos(DOT(vfrom, vto));
311     res = d*d;
312     d = R2ANG(rbf2->crad) - R2ANG(rbf1->crad);
313     res += d*d;
314     /* neighborhood difference */
315     res += NEIGH_FACT2 * neighborhood_dist2( rbf1->gx, rbf1->gy,
316     rbf2->gx, rbf2->gy );
317     return(res);
318 greg 2.1 }
319    
320 greg 2.26
321 greg 2.1 /* Compute and insert migration along directed edge (may fork child) */
322     static MIGRATION *
323     create_migration(RBFNODE *from_rbf, RBFNODE *to_rbf)
324     {
325     MIGRATION *newmig;
326 greg 2.6 int i, j;
327 greg 2.1 /* check if exists already */
328     for (newmig = from_rbf->ejl; newmig != NULL;
329     newmig = nextedge(from_rbf,newmig))
330     if (newmig->rbfv[1] == to_rbf)
331     return(NULL);
332     /* else allocate */
333 greg 2.7 #ifdef DEBUG
334 greg 2.14 fprintf(stderr, "Building path from (theta,phi) (%.1f,%.1f) ",
335 greg 2.7 get_theta180(from_rbf->invec),
336     get_phi360(from_rbf->invec));
337 greg 2.14 fprintf(stderr, "to (%.1f,%.1f) with %d x %d matrix\n",
338 greg 2.7 get_theta180(to_rbf->invec),
339     get_phi360(to_rbf->invec),
340     from_rbf->nrbf, to_rbf->nrbf);
341     #endif
342 greg 2.1 newmig = new_migration(from_rbf, to_rbf);
343     if (run_subprocess())
344     return(newmig); /* child continues */
345 greg 2.27
346     /* compute transport plan */
347     compute_nDSFs(from_rbf, to_rbf);
348     plan_transport(newmig);
349 greg 2.6
350 greg 2.1 for (i = from_rbf->nrbf; i--; ) { /* normalize final matrix */
351 greg 2.6 double nf = rbf_volume(&from_rbf->rbfa[i]);
352 greg 2.1 if (nf <= FTINY) continue;
353     nf = from_rbf->vtotal / nf;
354     for (j = to_rbf->nrbf; j--; )
355 greg 2.6 mtx_coef(newmig,i,j) *= nf; /* row now sums to 1.0 */
356 greg 2.1 }
357     end_subprocess(); /* exit here if subprocess */
358     return(newmig);
359     }
360    
361     /* Check if prospective vertex would create overlapping triangle */
362     static int
363     overlaps_tri(const RBFNODE *bv0, const RBFNODE *bv1, const RBFNODE *pv)
364     {
365     const MIGRATION *ej;
366     RBFNODE *vother[2];
367     int im_rev;
368     /* find shared edge in mesh */
369     for (ej = pv->ejl; ej != NULL; ej = nextedge(pv,ej)) {
370     const RBFNODE *tv = opp_rbf(pv,ej);
371     if (tv == bv0) {
372     im_rev = is_rev_tri(ej->rbfv[0]->invec,
373     ej->rbfv[1]->invec, bv1->invec);
374     break;
375     }
376     if (tv == bv1) {
377     im_rev = is_rev_tri(ej->rbfv[0]->invec,
378     ej->rbfv[1]->invec, bv0->invec);
379     break;
380     }
381     }
382     if (!get_triangles(vother, ej)) /* triangle on same side? */
383     return(0);
384     return(vother[im_rev] != NULL);
385     }
386    
387 greg 2.14 /* Find convex hull vertex to complete triangle (oriented call) */
388 greg 2.1 static RBFNODE *
389     find_chull_vert(const RBFNODE *rbf0, const RBFNODE *rbf1)
390     {
391     FVECT vmid, vejn, vp;
392     RBFNODE *rbf, *rbfbest = NULL;
393     double dprod, area2, bestarea2 = FHUGE, bestdprod = -.5;
394    
395     VSUB(vejn, rbf1->invec, rbf0->invec);
396     VADD(vmid, rbf0->invec, rbf1->invec);
397     if (normalize(vejn) == 0 || normalize(vmid) == 0)
398     return(NULL);
399     /* XXX exhaustive search */
400     /* Find triangle with minimum rotation from perpendicular */
401     for (rbf = dsf_list; rbf != NULL; rbf = rbf->next) {
402     if ((rbf == rbf0) | (rbf == rbf1))
403     continue;
404     tri_orient(vp, rbf0->invec, rbf1->invec, rbf->invec);
405     if (DOT(vp, vmid) <= FTINY)
406     continue; /* wrong orientation */
407     area2 = .25*DOT(vp,vp);
408 greg 2.14 VSUB(vp, rbf->invec, vmid);
409 greg 2.1 dprod = -DOT(vp, vejn);
410     VSUM(vp, vp, vejn, dprod); /* above guarantees non-zero */
411     dprod = DOT(vp, vmid) / VLEN(vp);
412     if (dprod <= bestdprod + FTINY*(1 - 2*(area2 < bestarea2)))
413     continue; /* found better already */
414     if (overlaps_tri(rbf0, rbf1, rbf))
415     continue; /* overlaps another triangle */
416     rbfbest = rbf;
417     bestdprod = dprod; /* new one to beat */
418     bestarea2 = area2;
419     }
420     return(rbfbest);
421     }
422    
423     /* Create new migration edge and grow mesh recursively around it */
424     static void
425     mesh_from_edge(MIGRATION *edge)
426     {
427     MIGRATION *ej0, *ej1;
428     RBFNODE *tvert[2];
429    
430     if (edge == NULL)
431     return;
432     /* triangle on either side? */
433     get_triangles(tvert, edge);
434     if (tvert[0] == NULL) { /* grow mesh on right */
435     tvert[0] = find_chull_vert(edge->rbfv[0], edge->rbfv[1]);
436     if (tvert[0] != NULL) {
437     if (tvert[0]->ord > edge->rbfv[0]->ord)
438     ej0 = create_migration(edge->rbfv[0], tvert[0]);
439     else
440     ej0 = create_migration(tvert[0], edge->rbfv[0]);
441     if (tvert[0]->ord > edge->rbfv[1]->ord)
442     ej1 = create_migration(edge->rbfv[1], tvert[0]);
443     else
444     ej1 = create_migration(tvert[0], edge->rbfv[1]);
445     mesh_from_edge(ej0);
446     mesh_from_edge(ej1);
447 greg 2.28 return;
448 greg 2.1 }
449 greg 2.28 }
450     if (tvert[1] == NULL) { /* grow mesh on left */
451 greg 2.1 tvert[1] = find_chull_vert(edge->rbfv[1], edge->rbfv[0]);
452     if (tvert[1] != NULL) {
453     if (tvert[1]->ord > edge->rbfv[0]->ord)
454     ej0 = create_migration(edge->rbfv[0], tvert[1]);
455     else
456     ej0 = create_migration(tvert[1], edge->rbfv[0]);
457     if (tvert[1]->ord > edge->rbfv[1]->ord)
458     ej1 = create_migration(edge->rbfv[1], tvert[1]);
459     else
460     ej1 = create_migration(tvert[1], edge->rbfv[1]);
461     mesh_from_edge(ej0);
462     mesh_from_edge(ej1);
463     }
464     }
465     }
466 greg 2.15
467     /* Add normal direction if missing */
468     static void
469     check_normal_incidence(void)
470     {
471 greg 2.25 static FVECT norm_vec = {.0, .0, 1.};
472 greg 2.16 const int saved_nprocs = nprocs;
473     RBFNODE *near_rbf, *mir_rbf, *rbf;
474     double bestd;
475     int n;
476 greg 2.15
477     if (dsf_list == NULL)
478     return; /* XXX should be error? */
479     near_rbf = dsf_list;
480     bestd = input_orient*near_rbf->invec[2];
481     if (single_plane_incident) { /* ordered plane incidence? */
482     if (bestd >= 1.-2.*FTINY)
483     return; /* already have normal */
484     } else {
485     switch (inp_coverage) {
486     case INP_QUAD1:
487     case INP_QUAD2:
488     case INP_QUAD3:
489     case INP_QUAD4:
490     break; /* quadrilateral symmetry? */
491     default:
492     return; /* else we can interpolate */
493     }
494     for (rbf = near_rbf->next; rbf != NULL; rbf = rbf->next) {
495     const double d = input_orient*rbf->invec[2];
496     if (d >= 1.-2.*FTINY)
497     return; /* seems we have normal */
498     if (d > bestd) {
499     near_rbf = rbf;
500     bestd = d;
501     }
502     }
503     }
504     if (mig_list != NULL) { /* need to be called first */
505     fprintf(stderr, "%s: Late call to check_normal_incidence()\n",
506     progname);
507     exit(1);
508     }
509     #ifdef DEBUG
510     fprintf(stderr, "Interpolating normal incidence by mirroring (%.1f,%.1f)\n",
511     get_theta180(near_rbf->invec), get_phi360(near_rbf->invec));
512     #endif
513     /* mirror nearest incidence */
514     n = sizeof(RBFNODE) + sizeof(RBFVAL)*(near_rbf->nrbf-1);
515     mir_rbf = (RBFNODE *)malloc(n);
516     if (mir_rbf == NULL)
517     goto memerr;
518     memcpy(mir_rbf, near_rbf, n);
519     mir_rbf->ord = near_rbf->ord - 1; /* not used, I think */
520     mir_rbf->next = NULL;
521 greg 2.22 mir_rbf->ejl = NULL;
522 greg 2.15 rev_rbf_symmetry(mir_rbf, MIRROR_X|MIRROR_Y);
523     nprocs = 1; /* compute migration matrix */
524 greg 2.22 if (create_migration(mir_rbf, near_rbf) == NULL)
525 greg 2.15 exit(1); /* XXX should never happen! */
526 greg 2.25 norm_vec[2] = input_orient; /* interpolate normal dist. */
527 greg 2.29 rbf = e_advect_rbf(mig_list, norm_vec, 0);
528 greg 2.15 nprocs = saved_nprocs; /* final clean-up */
529     free(mir_rbf);
530     free(mig_list);
531     mig_list = near_rbf->ejl = NULL;
532     insert_dsf(rbf); /* insert interpolated normal */
533     return;
534     memerr:
535     fprintf(stderr, "%s: Out of memory in check_normal_incidence()\n",
536     progname);
537     exit(1);
538     }
539 greg 2.1
540     /* Build our triangle mesh from recorded RBFs */
541     void
542     build_mesh(void)
543     {
544     double best2 = M_PI*M_PI;
545     RBFNODE *shrt_edj[2];
546     RBFNODE *rbf0, *rbf1;
547 greg 2.30 /* average specular peak */
548     comp_bsdf_spec();
549 greg 2.15 /* add normal if needed */
550     check_normal_incidence();
551 greg 2.1 /* check if isotropic */
552     if (single_plane_incident) {
553     for (rbf0 = dsf_list; rbf0 != NULL; rbf0 = rbf0->next)
554     if (rbf0->next != NULL)
555     create_migration(rbf0, rbf0->next);
556     await_children(nchild);
557     return;
558     }
559     shrt_edj[0] = shrt_edj[1] = NULL; /* start w/ shortest edge */
560     for (rbf0 = dsf_list; rbf0 != NULL; rbf0 = rbf0->next)
561     for (rbf1 = rbf0->next; rbf1 != NULL; rbf1 = rbf1->next) {
562     double dist2 = 2. - 2.*DOT(rbf0->invec,rbf1->invec);
563     if (dist2 < best2) {
564     shrt_edj[0] = rbf0;
565     shrt_edj[1] = rbf1;
566     best2 = dist2;
567     }
568     }
569     if (shrt_edj[0] == NULL) {
570     fprintf(stderr, "%s: Cannot find shortest edge\n", progname);
571     exit(1);
572     }
573     /* build mesh from this edge */
574     if (shrt_edj[0]->ord < shrt_edj[1]->ord)
575     mesh_from_edge(create_migration(shrt_edj[0], shrt_edj[1]));
576     else
577     mesh_from_edge(create_migration(shrt_edj[1], shrt_edj[0]));
578     /* complete migrations */
579     await_children(nchild);
580     }