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root/radiance/ray/src/rt/ambcomp.c
Revision: 2.77
Committed: Fri Apr 21 16:07:29 2017 UTC (7 years ago) by greg
Content type: text/plain
Branch: MAIN
CVS Tags: rad5R1
Changes since 2.76: +9 -5 lines
Log Message:
Fixed issue where ambient super-samples were being left off deep ray trees

File Contents

# User Rev Content
1 greg 1.1 #ifndef lint
2 greg 2.77 static const char RCSid[] = "$Id: ambcomp.c,v 2.76 2017/01/26 16:46:58 greg Exp $";
3 greg 1.1 #endif
4     /*
5     * Routines to compute "ambient" values using Monte Carlo
6 greg 2.9 *
7 greg 2.27 * Hessian calculations based on "Practical Hessian-Based Error Control
8     * for Irradiance Caching" by Schwarzhaupt, Wann Jensen, & Jarosz
9     * from ACM SIGGRAPH Asia 2012 conference proceedings.
10     *
11 greg 2.46 * Added book-keeping optimization to avoid calculations that would
12     * cancel due to traversal both directions on edges that are adjacent
13     * to same-valued triangles. This cuts about half of Hessian math.
14     *
15 greg 2.9 * Declarations of external symbols in ambient.h
16     */
17    
18 greg 2.10 #include "copyright.h"
19 greg 1.1
20     #include "ray.h"
21 greg 2.25 #include "ambient.h"
22     #include "random.h"
23 greg 1.1
24 greg 2.63 #ifndef OLDAMB
25 greg 1.1
26 greg 2.26 extern void SDsquare2disk(double ds[2], double seedx, double seedy);
27    
28     typedef struct {
29 greg 2.44 COLOR v; /* hemisphere sample value */
30 greg 2.47 float d; /* reciprocal distance (1/rt) */
31 greg 2.44 FVECT p; /* intersection point */
32     } AMBSAMP; /* sample value */
33    
34     typedef struct {
35 greg 2.26 RAY *rp; /* originating ray sample */
36     int ns; /* number of samples per axis */
37 greg 2.61 int sampOK; /* acquired full sample set? */
38 greg 2.26 COLOR acoef; /* division contribution coefficient */
39 greg 2.61 double acol[3]; /* accumulated color */
40     FVECT ux, uy; /* tangent axis unit vectors */
41 greg 2.44 AMBSAMP sa[1]; /* sample array (extends struct) */
42 greg 2.26 } AMBHEMI; /* ambient sample hemisphere */
43    
44 greg 2.56 #define AI(h,i,j) ((i)*(h)->ns + (j))
45     #define ambsam(h,i,j) (h)->sa[AI(h,i,j)]
46 greg 2.26
47 greg 2.27 typedef struct {
48 greg 2.35 FVECT r_i, r_i1, e_i, rcp, rI2_eJ2;
49     double I1, I2;
50 greg 2.27 } FFTRI; /* vectors and coefficients for Hessian calculation */
51    
52 greg 2.26
53 greg 2.61 static int
54 greg 2.73 ambcollision( /* proposed direciton collides? */
55     AMBHEMI *hp,
56     int i,
57     int j,
58     FVECT dv
59     )
60     {
61 greg 2.74 double cos_thresh;
62     int ii, jj;
63 greg 2.75 /* min. spacing = 1/4th division */
64     cos_thresh = (PI/4.)/(double)hp->ns;
65 greg 2.74 cos_thresh = 1. - .5*cos_thresh*cos_thresh;
66     /* check existing neighbors */
67 greg 2.73 for (ii = i-1; ii <= i+1; ii++) {
68     if (ii < 0) continue;
69     if (ii >= hp->ns) break;
70     for (jj = j-1; jj <= j+1; jj++) {
71     AMBSAMP *ap;
72     FVECT avec;
73     double dprod;
74     if (jj < 0) continue;
75     if (jj >= hp->ns) break;
76     if ((ii==i) & (jj==j)) continue;
77     ap = &ambsam(hp,ii,jj);
78 greg 2.74 if (ap->d <= .5/FHUGE)
79     continue; /* no one home */
80 greg 2.73 VSUB(avec, ap->p, hp->rp->rop);
81     dprod = DOT(avec, dv);
82     if (dprod >= cos_thresh*VLEN(avec))
83     return(1); /* collision */
84     }
85     }
86 greg 2.74 return(0); /* nothing to worry about */
87 greg 2.73 }
88    
89    
90     static int
91 greg 2.61 ambsample( /* initial ambient division sample */
92     AMBHEMI *hp,
93     int i,
94     int j,
95     int n
96 greg 2.26 )
97     {
98 greg 2.61 AMBSAMP *ap = &ambsam(hp,i,j);
99     RAY ar;
100 greg 2.41 int hlist[3], ii;
101     double spt[2], zd;
102 greg 2.61 /* generate hemispherical sample */
103 greg 2.26 /* ambient coefficient for weight */
104     if (ambacc > FTINY)
105 greg 2.61 setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
106 greg 2.26 else
107 greg 2.61 copycolor(ar.rcoef, hp->acoef);
108 greg 2.62 if (rayorigin(&ar, AMBIENT, hp->rp, ar.rcoef) < 0)
109 greg 2.41 return(0);
110 greg 2.26 if (ambacc > FTINY) {
111 greg 2.61 multcolor(ar.rcoef, hp->acoef);
112     scalecolor(ar.rcoef, 1./AVGREFL);
113 greg 2.41 }
114     hlist[0] = hp->rp->rno;
115 greg 2.46 hlist[1] = j;
116     hlist[2] = i;
117 greg 2.41 multisamp(spt, 2, urand(ilhash(hlist,3)+n));
118 greg 2.73 resample:
119 greg 2.46 SDsquare2disk(spt, (j+spt[1])/hp->ns, (i+spt[0])/hp->ns);
120 greg 2.26 zd = sqrt(1. - spt[0]*spt[0] - spt[1]*spt[1]);
121     for (ii = 3; ii--; )
122 greg 2.61 ar.rdir[ii] = spt[0]*hp->ux[ii] +
123 greg 2.26 spt[1]*hp->uy[ii] +
124     zd*hp->rp->ron[ii];
125 greg 2.61 checknorm(ar.rdir);
126 greg 2.73 /* avoid coincident samples */
127     if (!n && ambcollision(hp, i, j, ar.rdir)) {
128     spt[0] = frandom(); spt[1] = frandom();
129 greg 2.75 goto resample; /* reject this sample */
130 greg 2.73 }
131 greg 2.56 dimlist[ndims++] = AI(hp,i,j) + 90171;
132 greg 2.61 rayvalue(&ar); /* evaluate ray */
133     ndims--;
134     if (ar.rt <= FTINY)
135     return(0); /* should never happen */
136     multcolor(ar.rcol, ar.rcoef); /* apply coefficient */
137 greg 2.62 if (ar.rt*ap->d < 1.0) /* new/closer distance? */
138 greg 2.61 ap->d = 1.0/ar.rt;
139     if (!n) { /* record first vertex & value */
140 greg 2.76 if (ar.rt > 10.0*thescene.cusize + 1000.)
141     ar.rt = 10.0*thescene.cusize + 1000.;
142 greg 2.61 VSUM(ap->p, ar.rorg, ar.rdir, ar.rt);
143     copycolor(ap->v, ar.rcol);
144     } else { /* else update recorded value */
145     hp->acol[RED] -= colval(ap->v,RED);
146     hp->acol[GRN] -= colval(ap->v,GRN);
147     hp->acol[BLU] -= colval(ap->v,BLU);
148     zd = 1.0/(double)(n+1);
149     scalecolor(ar.rcol, zd);
150     zd *= (double)n;
151     scalecolor(ap->v, zd);
152     addcolor(ap->v, ar.rcol);
153     }
154     addcolor(hp->acol, ap->v); /* add to our sum */
155 greg 2.41 return(1);
156     }
157    
158    
159     /* Estimate errors based on ambient division differences */
160     static float *
161     getambdiffs(AMBHEMI *hp)
162     {
163 greg 2.77 const double normf = 1./bright(hp->acoef);
164 greg 2.55 float *earr = (float *)calloc(hp->ns*hp->ns, sizeof(float));
165 greg 2.41 float *ep;
166 greg 2.42 AMBSAMP *ap;
167 greg 2.41 double b, d2;
168     int i, j;
169    
170     if (earr == NULL) /* out of memory? */
171     return(NULL);
172     /* compute squared neighbor diffs */
173 greg 2.42 for (ap = hp->sa, ep = earr, i = 0; i < hp->ns; i++)
174     for (j = 0; j < hp->ns; j++, ap++, ep++) {
175     b = bright(ap[0].v);
176 greg 2.41 if (i) { /* from above */
177 greg 2.77 d2 = normf*(b - bright(ap[-hp->ns].v));
178 greg 2.41 d2 *= d2;
179     ep[0] += d2;
180     ep[-hp->ns] += d2;
181     }
182 greg 2.55 if (!j) continue;
183     /* from behind */
184 greg 2.77 d2 = normf*(b - bright(ap[-1].v));
185 greg 2.55 d2 *= d2;
186     ep[0] += d2;
187     ep[-1] += d2;
188     if (!i) continue;
189     /* diagonal */
190 greg 2.77 d2 = normf*(b - bright(ap[-hp->ns-1].v));
191 greg 2.55 d2 *= d2;
192     ep[0] += d2;
193     ep[-hp->ns-1] += d2;
194 greg 2.41 }
195     /* correct for number of neighbors */
196 greg 2.55 earr[0] *= 8./3.;
197     earr[hp->ns-1] *= 8./3.;
198     earr[(hp->ns-1)*hp->ns] *= 8./3.;
199     earr[(hp->ns-1)*hp->ns + hp->ns-1] *= 8./3.;
200 greg 2.41 for (i = 1; i < hp->ns-1; i++) {
201 greg 2.55 earr[i*hp->ns] *= 8./5.;
202     earr[i*hp->ns + hp->ns-1] *= 8./5.;
203 greg 2.41 }
204     for (j = 1; j < hp->ns-1; j++) {
205 greg 2.55 earr[j] *= 8./5.;
206     earr[(hp->ns-1)*hp->ns + j] *= 8./5.;
207 greg 2.41 }
208     return(earr);
209     }
210    
211    
212 greg 2.43 /* Perform super-sampling on hemisphere (introduces bias) */
213 greg 2.41 static void
214 greg 2.61 ambsupersamp(AMBHEMI *hp, int cnt)
215 greg 2.41 {
216     float *earr = getambdiffs(hp);
217 greg 2.54 double e2rem = 0;
218 greg 2.41 AMBSAMP *ap;
219     float *ep;
220 greg 2.55 int i, j, n, nss;
221 greg 2.41
222     if (earr == NULL) /* just skip calc. if no memory */
223     return;
224 greg 2.54 /* accumulate estimated variances */
225 greg 2.55 for (ep = earr + hp->ns*hp->ns; ep > earr; )
226     e2rem += *--ep;
227 greg 2.41 ep = earr; /* perform super-sampling */
228     for (ap = hp->sa, i = 0; i < hp->ns; i++)
229     for (j = 0; j < hp->ns; j++, ap++) {
230 greg 2.55 if (e2rem <= FTINY)
231     goto done; /* nothing left to do */
232     nss = *ep/e2rem*cnt + frandom();
233 greg 2.62 for (n = 1; n <= nss && ambsample(hp,i,j,n); n++)
234 greg 2.77 if (!--cnt) goto done;
235 greg 2.61 e2rem -= *ep++; /* update remainder */
236 greg 2.41 }
237 greg 2.55 done:
238 greg 2.41 free(earr);
239     }
240    
241    
242 greg 2.61 static AMBHEMI *
243     samp_hemi( /* sample indirect hemisphere */
244     COLOR rcol,
245     RAY *r,
246     double wt
247     )
248     {
249     AMBHEMI *hp;
250     double d;
251     int n, i, j;
252 greg 2.77 /* insignificance check */
253     if (bright(rcol) <= FTINY)
254     return(NULL);
255 greg 2.61 /* set number of divisions */
256     if (ambacc <= FTINY &&
257     wt > (d = 0.8*intens(rcol)*r->rweight/(ambdiv*minweight)))
258     wt = d; /* avoid ray termination */
259     n = sqrt(ambdiv * wt) + 0.5;
260 greg 2.68 i = 1 + 5*(ambacc > FTINY); /* minimum number of samples */
261 greg 2.61 if (n < i)
262     n = i;
263     /* allocate sampling array */
264     hp = (AMBHEMI *)malloc(sizeof(AMBHEMI) + sizeof(AMBSAMP)*(n*n - 1));
265     if (hp == NULL)
266     error(SYSTEM, "out of memory in samp_hemi");
267     hp->rp = r;
268     hp->ns = n;
269     hp->acol[RED] = hp->acol[GRN] = hp->acol[BLU] = 0.0;
270 greg 2.62 memset(hp->sa, 0, sizeof(AMBSAMP)*n*n);
271 greg 2.61 hp->sampOK = 0;
272     /* assign coefficient */
273     copycolor(hp->acoef, rcol);
274     d = 1.0/(n*n);
275     scalecolor(hp->acoef, d);
276     /* make tangent plane axes */
277 greg 2.70 if (!getperpendicular(hp->ux, r->ron, 1))
278 greg 2.61 error(CONSISTENCY, "bad ray direction in samp_hemi");
279     VCROSS(hp->uy, r->ron, hp->ux);
280     /* sample divisions */
281     for (i = hp->ns; i--; )
282     for (j = hp->ns; j--; )
283     hp->sampOK += ambsample(hp, i, j, 0);
284     copycolor(rcol, hp->acol);
285     if (!hp->sampOK) { /* utter failure? */
286     free(hp);
287     return(NULL);
288     }
289     if (hp->sampOK < hp->ns*hp->ns) {
290     hp->sampOK *= -1; /* soft failure */
291     return(hp);
292     }
293     n = ambssamp*wt + 0.5;
294     if (n > 8) { /* perform super-sampling? */
295     ambsupersamp(hp, n);
296     copycolor(rcol, hp->acol);
297     }
298     return(hp); /* all is well */
299     }
300    
301    
302 greg 2.46 /* Return brightness of farthest ambient sample */
303     static double
304 greg 2.56 back_ambval(AMBHEMI *hp, const int n1, const int n2, const int n3)
305 greg 2.46 {
306 greg 2.56 if (hp->sa[n1].d <= hp->sa[n2].d) {
307     if (hp->sa[n1].d <= hp->sa[n3].d)
308     return(colval(hp->sa[n1].v,CIEY));
309     return(colval(hp->sa[n3].v,CIEY));
310     }
311     if (hp->sa[n2].d <= hp->sa[n3].d)
312     return(colval(hp->sa[n2].v,CIEY));
313     return(colval(hp->sa[n3].v,CIEY));
314 greg 2.46 }
315    
316    
317 greg 2.27 /* Compute vectors and coefficients for Hessian/gradient calcs */
318     static void
319 greg 2.56 comp_fftri(FFTRI *ftp, AMBHEMI *hp, const int n0, const int n1)
320 greg 2.27 {
321 greg 2.56 double rdot_cp, dot_e, dot_er, rdot_r, rdot_r1, J2;
322     int ii;
323    
324     VSUB(ftp->r_i, hp->sa[n0].p, hp->rp->rop);
325     VSUB(ftp->r_i1, hp->sa[n1].p, hp->rp->rop);
326     VSUB(ftp->e_i, hp->sa[n1].p, hp->sa[n0].p);
327 greg 2.35 VCROSS(ftp->rcp, ftp->r_i, ftp->r_i1);
328     rdot_cp = 1.0/DOT(ftp->rcp,ftp->rcp);
329 greg 2.27 dot_e = DOT(ftp->e_i,ftp->e_i);
330     dot_er = DOT(ftp->e_i, ftp->r_i);
331 greg 2.32 rdot_r = 1.0/DOT(ftp->r_i,ftp->r_i);
332     rdot_r1 = 1.0/DOT(ftp->r_i1,ftp->r_i1);
333     ftp->I1 = acos( DOT(ftp->r_i, ftp->r_i1) * sqrt(rdot_r*rdot_r1) ) *
334 greg 2.35 sqrt( rdot_cp );
335 greg 2.32 ftp->I2 = ( DOT(ftp->e_i, ftp->r_i1)*rdot_r1 - dot_er*rdot_r +
336 greg 2.35 dot_e*ftp->I1 )*0.5*rdot_cp;
337 greg 2.32 J2 = ( 0.5*(rdot_r - rdot_r1) - dot_er*ftp->I2 ) / dot_e;
338 greg 2.46 for (ii = 3; ii--; )
339     ftp->rI2_eJ2[ii] = ftp->I2*ftp->r_i[ii] + J2*ftp->e_i[ii];
340 greg 2.27 }
341    
342    
343 greg 2.28 /* Compose 3x3 matrix from two vectors */
344 greg 2.27 static void
345     compose_matrix(FVECT mat[3], FVECT va, FVECT vb)
346     {
347     mat[0][0] = 2.0*va[0]*vb[0];
348     mat[1][1] = 2.0*va[1]*vb[1];
349     mat[2][2] = 2.0*va[2]*vb[2];
350     mat[0][1] = mat[1][0] = va[0]*vb[1] + va[1]*vb[0];
351     mat[0][2] = mat[2][0] = va[0]*vb[2] + va[2]*vb[0];
352     mat[1][2] = mat[2][1] = va[1]*vb[2] + va[2]*vb[1];
353     }
354    
355    
356     /* Compute partial 3x3 Hessian matrix for edge */
357     static void
358     comp_hessian(FVECT hess[3], FFTRI *ftp, FVECT nrm)
359     {
360 greg 2.35 FVECT ncp;
361 greg 2.27 FVECT m1[3], m2[3], m3[3], m4[3];
362     double d1, d2, d3, d4;
363     double I3, J3, K3;
364     int i, j;
365     /* compute intermediate coefficients */
366     d1 = 1.0/DOT(ftp->r_i,ftp->r_i);
367     d2 = 1.0/DOT(ftp->r_i1,ftp->r_i1);
368     d3 = 1.0/DOT(ftp->e_i,ftp->e_i);
369     d4 = DOT(ftp->e_i, ftp->r_i);
370 greg 2.35 I3 = ( DOT(ftp->e_i, ftp->r_i1)*d2*d2 - d4*d1*d1 + 3.0/d3*ftp->I2 )
371     / ( 4.0*DOT(ftp->rcp,ftp->rcp) );
372 greg 2.27 J3 = 0.25*d3*(d1*d1 - d2*d2) - d4*d3*I3;
373     K3 = d3*(ftp->I2 - I3/d1 - 2.0*d4*J3);
374     /* intermediate matrices */
375 greg 2.35 VCROSS(ncp, nrm, ftp->e_i);
376     compose_matrix(m1, ncp, ftp->rI2_eJ2);
377 greg 2.27 compose_matrix(m2, ftp->r_i, ftp->r_i);
378     compose_matrix(m3, ftp->e_i, ftp->e_i);
379     compose_matrix(m4, ftp->r_i, ftp->e_i);
380 greg 2.35 d1 = DOT(nrm, ftp->rcp);
381 greg 2.27 d2 = -d1*ftp->I2;
382     d1 *= 2.0;
383     for (i = 3; i--; ) /* final matrix sum */
384     for (j = 3; j--; ) {
385     hess[i][j] = m1[i][j] + d1*( I3*m2[i][j] + K3*m3[i][j] +
386     2.0*J3*m4[i][j] );
387     hess[i][j] += d2*(i==j);
388 greg 2.46 hess[i][j] *= -1.0/PI;
389 greg 2.27 }
390     }
391    
392    
393     /* Reverse hessian calculation result for edge in other direction */
394     static void
395     rev_hessian(FVECT hess[3])
396     {
397     int i;
398    
399     for (i = 3; i--; ) {
400     hess[i][0] = -hess[i][0];
401     hess[i][1] = -hess[i][1];
402     hess[i][2] = -hess[i][2];
403     }
404     }
405    
406    
407     /* Add to radiometric Hessian from the given triangle */
408     static void
409     add2hessian(FVECT hess[3], FVECT ehess1[3],
410 greg 2.46 FVECT ehess2[3], FVECT ehess3[3], double v)
411 greg 2.27 {
412     int i, j;
413    
414     for (i = 3; i--; )
415     for (j = 3; j--; )
416     hess[i][j] += v*( ehess1[i][j] + ehess2[i][j] + ehess3[i][j] );
417     }
418    
419    
420     /* Compute partial displacement form factor gradient for edge */
421     static void
422     comp_gradient(FVECT grad, FFTRI *ftp, FVECT nrm)
423     {
424 greg 2.35 FVECT ncp;
425 greg 2.27 double f1;
426     int i;
427    
428 greg 2.35 f1 = 2.0*DOT(nrm, ftp->rcp);
429     VCROSS(ncp, nrm, ftp->e_i);
430 greg 2.27 for (i = 3; i--; )
431 greg 2.46 grad[i] = (0.5/PI)*( ftp->I1*ncp[i] + f1*ftp->rI2_eJ2[i] );
432 greg 2.27 }
433    
434    
435     /* Reverse gradient calculation result for edge in other direction */
436     static void
437     rev_gradient(FVECT grad)
438     {
439     grad[0] = -grad[0];
440     grad[1] = -grad[1];
441     grad[2] = -grad[2];
442     }
443    
444    
445     /* Add to displacement gradient from the given triangle */
446     static void
447 greg 2.46 add2gradient(FVECT grad, FVECT egrad1, FVECT egrad2, FVECT egrad3, double v)
448 greg 2.27 {
449     int i;
450    
451     for (i = 3; i--; )
452     grad[i] += v*( egrad1[i] + egrad2[i] + egrad3[i] );
453     }
454    
455    
456     /* Compute anisotropic radii and eigenvector directions */
457 greg 2.53 static void
458 greg 2.27 eigenvectors(FVECT uv[2], float ra[2], FVECT hessian[3])
459     {
460     double hess2[2][2];
461     FVECT a, b;
462     double evalue[2], slope1, xmag1;
463     int i;
464     /* project Hessian to sample plane */
465     for (i = 3; i--; ) {
466     a[i] = DOT(hessian[i], uv[0]);
467     b[i] = DOT(hessian[i], uv[1]);
468     }
469     hess2[0][0] = DOT(uv[0], a);
470     hess2[0][1] = DOT(uv[0], b);
471     hess2[1][0] = DOT(uv[1], a);
472     hess2[1][1] = DOT(uv[1], b);
473 greg 2.38 /* compute eigenvalue(s) */
474     i = quadratic(evalue, 1.0, -hess2[0][0]-hess2[1][1],
475     hess2[0][0]*hess2[1][1]-hess2[0][1]*hess2[1][0]);
476     if (i == 1) /* double-root (circle) */
477     evalue[1] = evalue[0];
478     if (!i || ((evalue[0] = fabs(evalue[0])) <= FTINY*FTINY) |
479 greg 2.53 ((evalue[1] = fabs(evalue[1])) <= FTINY*FTINY) ) {
480     ra[0] = ra[1] = maxarad;
481     return;
482     }
483 greg 2.27 if (evalue[0] > evalue[1]) {
484 greg 2.29 ra[0] = sqrt(sqrt(4.0/evalue[0]));
485     ra[1] = sqrt(sqrt(4.0/evalue[1]));
486 greg 2.27 slope1 = evalue[1];
487     } else {
488 greg 2.29 ra[0] = sqrt(sqrt(4.0/evalue[1]));
489     ra[1] = sqrt(sqrt(4.0/evalue[0]));
490 greg 2.27 slope1 = evalue[0];
491     }
492     /* compute unit eigenvectors */
493     if (fabs(hess2[0][1]) <= FTINY)
494     return; /* uv OK as is */
495     slope1 = (slope1 - hess2[0][0]) / hess2[0][1];
496     xmag1 = sqrt(1.0/(1.0 + slope1*slope1));
497     for (i = 3; i--; ) {
498     b[i] = xmag1*uv[0][i] + slope1*xmag1*uv[1][i];
499     a[i] = slope1*xmag1*uv[0][i] - xmag1*uv[1][i];
500     }
501     VCOPY(uv[0], a);
502     VCOPY(uv[1], b);
503     }
504    
505    
506 greg 2.26 static void
507     ambHessian( /* anisotropic radii & pos. gradient */
508     AMBHEMI *hp,
509     FVECT uv[2], /* returned */
510 greg 2.28 float ra[2], /* returned (optional) */
511     float pg[2] /* returned (optional) */
512 greg 2.26 )
513     {
514 greg 2.27 static char memerrmsg[] = "out of memory in ambHessian()";
515     FVECT (*hessrow)[3] = NULL;
516     FVECT *gradrow = NULL;
517     FVECT hessian[3];
518     FVECT gradient;
519     FFTRI fftr;
520     int i, j;
521     /* be sure to assign unit vectors */
522     VCOPY(uv[0], hp->ux);
523     VCOPY(uv[1], hp->uy);
524     /* clock-wise vertex traversal from sample POV */
525     if (ra != NULL) { /* initialize Hessian row buffer */
526 greg 2.28 hessrow = (FVECT (*)[3])malloc(sizeof(FVECT)*3*(hp->ns-1));
527 greg 2.27 if (hessrow == NULL)
528     error(SYSTEM, memerrmsg);
529     memset(hessian, 0, sizeof(hessian));
530     } else if (pg == NULL) /* bogus call? */
531     return;
532     if (pg != NULL) { /* initialize form factor row buffer */
533 greg 2.28 gradrow = (FVECT *)malloc(sizeof(FVECT)*(hp->ns-1));
534 greg 2.27 if (gradrow == NULL)
535     error(SYSTEM, memerrmsg);
536     memset(gradient, 0, sizeof(gradient));
537     }
538     /* compute first row of edges */
539     for (j = 0; j < hp->ns-1; j++) {
540 greg 2.56 comp_fftri(&fftr, hp, AI(hp,0,j), AI(hp,0,j+1));
541 greg 2.27 if (hessrow != NULL)
542     comp_hessian(hessrow[j], &fftr, hp->rp->ron);
543     if (gradrow != NULL)
544     comp_gradient(gradrow[j], &fftr, hp->rp->ron);
545     }
546     /* sum each row of triangles */
547     for (i = 0; i < hp->ns-1; i++) {
548     FVECT hesscol[3]; /* compute first vertical edge */
549     FVECT gradcol;
550 greg 2.56 comp_fftri(&fftr, hp, AI(hp,i,0), AI(hp,i+1,0));
551 greg 2.27 if (hessrow != NULL)
552     comp_hessian(hesscol, &fftr, hp->rp->ron);
553     if (gradrow != NULL)
554     comp_gradient(gradcol, &fftr, hp->rp->ron);
555     for (j = 0; j < hp->ns-1; j++) {
556     FVECT hessdia[3]; /* compute triangle contributions */
557     FVECT graddia;
558 greg 2.46 double backg;
559 greg 2.56 backg = back_ambval(hp, AI(hp,i,j),
560     AI(hp,i,j+1), AI(hp,i+1,j));
561 greg 2.27 /* diagonal (inner) edge */
562 greg 2.56 comp_fftri(&fftr, hp, AI(hp,i,j+1), AI(hp,i+1,j));
563 greg 2.27 if (hessrow != NULL) {
564     comp_hessian(hessdia, &fftr, hp->rp->ron);
565     rev_hessian(hesscol);
566     add2hessian(hessian, hessrow[j], hessdia, hesscol, backg);
567     }
568 greg 2.39 if (gradrow != NULL) {
569 greg 2.27 comp_gradient(graddia, &fftr, hp->rp->ron);
570     rev_gradient(gradcol);
571     add2gradient(gradient, gradrow[j], graddia, gradcol, backg);
572     }
573     /* initialize edge in next row */
574 greg 2.56 comp_fftri(&fftr, hp, AI(hp,i+1,j+1), AI(hp,i+1,j));
575 greg 2.27 if (hessrow != NULL)
576     comp_hessian(hessrow[j], &fftr, hp->rp->ron);
577     if (gradrow != NULL)
578     comp_gradient(gradrow[j], &fftr, hp->rp->ron);
579     /* new column edge & paired triangle */
580 greg 2.56 backg = back_ambval(hp, AI(hp,i+1,j+1),
581     AI(hp,i+1,j), AI(hp,i,j+1));
582     comp_fftri(&fftr, hp, AI(hp,i,j+1), AI(hp,i+1,j+1));
583 greg 2.27 if (hessrow != NULL) {
584     comp_hessian(hesscol, &fftr, hp->rp->ron);
585     rev_hessian(hessdia);
586     add2hessian(hessian, hessrow[j], hessdia, hesscol, backg);
587     if (i < hp->ns-2)
588     rev_hessian(hessrow[j]);
589     }
590     if (gradrow != NULL) {
591     comp_gradient(gradcol, &fftr, hp->rp->ron);
592     rev_gradient(graddia);
593     add2gradient(gradient, gradrow[j], graddia, gradcol, backg);
594     if (i < hp->ns-2)
595     rev_gradient(gradrow[j]);
596     }
597     }
598     }
599     /* release row buffers */
600     if (hessrow != NULL) free(hessrow);
601     if (gradrow != NULL) free(gradrow);
602    
603     if (ra != NULL) /* extract eigenvectors & radii */
604     eigenvectors(uv, ra, hessian);
605 greg 2.32 if (pg != NULL) { /* tangential position gradient */
606     pg[0] = DOT(gradient, uv[0]);
607     pg[1] = DOT(gradient, uv[1]);
608 greg 2.27 }
609     }
610    
611    
612     /* Compute direction gradient from a hemispherical sampling */
613     static void
614     ambdirgrad(AMBHEMI *hp, FVECT uv[2], float dg[2])
615     {
616 greg 2.41 AMBSAMP *ap;
617     double dgsum[2];
618     int n;
619     FVECT vd;
620     double gfact;
621 greg 2.27
622 greg 2.29 dgsum[0] = dgsum[1] = 0.0; /* sum values times -tan(theta) */
623 greg 2.27 for (ap = hp->sa, n = hp->ns*hp->ns; n--; ap++) {
624     /* use vector for azimuth + 90deg */
625     VSUB(vd, ap->p, hp->rp->rop);
626 greg 2.29 /* brightness over cosine factor */
627     gfact = colval(ap->v,CIEY) / DOT(hp->rp->ron, vd);
628 greg 2.40 /* sine = proj_radius/vd_length */
629     dgsum[0] -= DOT(uv[1], vd) * gfact;
630     dgsum[1] += DOT(uv[0], vd) * gfact;
631 greg 2.26 }
632 greg 2.29 dg[0] = dgsum[0] / (hp->ns*hp->ns);
633     dg[1] = dgsum[1] / (hp->ns*hp->ns);
634 greg 2.26 }
635    
636 greg 2.27
637 greg 2.49 /* Compute potential light leak direction flags for cache value */
638     static uint32
639     ambcorral(AMBHEMI *hp, FVECT uv[2], const double r0, const double r1)
640 greg 2.47 {
641 greg 2.50 const double max_d = 1.0/(minarad*ambacc + 0.001);
642 greg 2.66 const double ang_res = 0.5*PI/hp->ns;
643     const double ang_step = ang_res/((int)(16/PI*ang_res) + 1.01);
644 greg 2.51 double avg_d = 0;
645 greg 2.50 uint32 flgs = 0;
646 greg 2.58 FVECT vec;
647 greg 2.62 double u, v;
648 greg 2.58 double ang, a1;
649 greg 2.50 int i, j;
650 greg 2.52 /* don't bother for a few samples */
651 greg 2.72 if (hp->ns < 8)
652 greg 2.52 return(0);
653     /* check distances overhead */
654 greg 2.51 for (i = hp->ns*3/4; i-- > hp->ns>>2; )
655     for (j = hp->ns*3/4; j-- > hp->ns>>2; )
656     avg_d += ambsam(hp,i,j).d;
657     avg_d *= 4.0/(hp->ns*hp->ns);
658 greg 2.52 if (avg_d*r0 >= 1.0) /* ceiling too low for corral? */
659     return(0);
660     if (avg_d >= max_d) /* insurance */
661 greg 2.51 return(0);
662     /* else circle around perimeter */
663 greg 2.47 for (i = 0; i < hp->ns; i++)
664     for (j = 0; j < hp->ns; j += !i|(i==hp->ns-1) ? 1 : hp->ns-1) {
665     AMBSAMP *ap = &ambsam(hp,i,j);
666 greg 2.50 if ((ap->d <= FTINY) | (ap->d >= max_d))
667     continue; /* too far or too near */
668 greg 2.47 VSUB(vec, ap->p, hp->rp->rop);
669 greg 2.62 u = DOT(vec, uv[0]);
670     v = DOT(vec, uv[1]);
671     if ((r0*r0*u*u + r1*r1*v*v) * ap->d*ap->d <= u*u + v*v)
672 greg 2.49 continue; /* occluder outside ellipse */
673     ang = atan2a(v, u); /* else set direction flags */
674 greg 2.66 for (a1 = ang-ang_res; a1 <= ang+ang_res; a1 += ang_step)
675 greg 2.50 flgs |= 1L<<(int)(16/PI*(a1 + 2.*PI*(a1 < 0)));
676 greg 2.47 }
677 greg 2.58 /* add low-angle incident (< 20deg) */
678     if (fabs(hp->rp->rod) <= 0.342) {
679     u = -DOT(hp->rp->rdir, uv[0]);
680     v = -DOT(hp->rp->rdir, uv[1]);
681     if ((r0*r0*u*u + r1*r1*v*v) > hp->rp->rot*hp->rp->rot) {
682     ang = atan2a(v, u);
683     ang += 2.*PI*(ang < 0);
684     ang *= 16/PI;
685     if ((ang < .5) | (ang >= 31.5))
686     flgs |= 0x80000001;
687     else
688     flgs |= 3L<<(int)(ang-.5);
689     }
690     }
691 greg 2.49 return(flgs);
692 greg 2.47 }
693    
694    
695 greg 2.26 int
696     doambient( /* compute ambient component */
697     COLOR rcol, /* input/output color */
698     RAY *r,
699     double wt,
700 greg 2.27 FVECT uv[2], /* returned (optional) */
701     float ra[2], /* returned (optional) */
702     float pg[2], /* returned (optional) */
703 greg 2.49 float dg[2], /* returned (optional) */
704     uint32 *crlp /* returned (optional) */
705 greg 2.26 )
706     {
707 greg 2.61 AMBHEMI *hp = samp_hemi(rcol, r, wt);
708 greg 2.41 FVECT my_uv[2];
709 greg 2.61 double d, K;
710 greg 2.41 AMBSAMP *ap;
711 greg 2.61 int i;
712     /* clear return values */
713 greg 2.26 if (uv != NULL)
714     memset(uv, 0, sizeof(FVECT)*2);
715     if (ra != NULL)
716     ra[0] = ra[1] = 0.0;
717     if (pg != NULL)
718     pg[0] = pg[1] = 0.0;
719     if (dg != NULL)
720     dg[0] = dg[1] = 0.0;
721 greg 2.49 if (crlp != NULL)
722     *crlp = 0;
723 greg 2.61 if (hp == NULL) /* sampling falure? */
724     return(0);
725    
726     if ((ra == NULL) & (pg == NULL) & (dg == NULL) ||
727 greg 2.68 (hp->sampOK < 0) | (hp->ns < 6)) {
728 greg 2.61 free(hp); /* Hessian not requested/possible */
729     return(-1); /* value-only return value */
730 greg 2.26 }
731 greg 2.61 if ((d = bright(rcol)) > FTINY) { /* normalize Y values */
732 greg 2.45 d = 0.99*(hp->ns*hp->ns)/d;
733 greg 2.38 K = 0.01;
734 greg 2.45 } else { /* or fall back on geometric Hessian */
735 greg 2.38 K = 1.0;
736     pg = NULL;
737     dg = NULL;
738 greg 2.53 crlp = NULL;
739 greg 2.38 }
740 greg 2.29 ap = hp->sa; /* relative Y channel from here on... */
741 greg 2.26 for (i = hp->ns*hp->ns; i--; ap++)
742 greg 2.38 colval(ap->v,CIEY) = bright(ap->v)*d + K;
743 greg 2.26
744     if (uv == NULL) /* make sure we have axis pointers */
745     uv = my_uv;
746     /* compute radii & pos. gradient */
747     ambHessian(hp, uv, ra, pg);
748 greg 2.29
749 greg 2.26 if (dg != NULL) /* compute direction gradient */
750     ambdirgrad(hp, uv, dg);
751 greg 2.29
752 greg 2.28 if (ra != NULL) { /* scale/clamp radii */
753 greg 2.35 if (pg != NULL) {
754     if (ra[0]*(d = fabs(pg[0])) > 1.0)
755     ra[0] = 1.0/d;
756     if (ra[1]*(d = fabs(pg[1])) > 1.0)
757     ra[1] = 1.0/d;
758 greg 2.48 if (ra[0] > ra[1])
759     ra[0] = ra[1];
760 greg 2.35 }
761 greg 2.29 if (ra[0] < minarad) {
762     ra[0] = minarad;
763     if (ra[1] < minarad)
764     ra[1] = minarad;
765     }
766 greg 2.60 ra[0] *= d = 1.0/sqrt(wt);
767 greg 2.26 if ((ra[1] *= d) > 2.0*ra[0])
768     ra[1] = 2.0*ra[0];
769 greg 2.28 if (ra[1] > maxarad) {
770     ra[1] = maxarad;
771     if (ra[0] > maxarad)
772     ra[0] = maxarad;
773     }
774 greg 2.53 /* flag encroached directions */
775 greg 2.71 if (crlp != NULL)
776 greg 2.49 *crlp = ambcorral(hp, uv, ra[0]*ambacc, ra[1]*ambacc);
777 greg 2.35 if (pg != NULL) { /* cap gradient if necessary */
778     d = pg[0]*pg[0]*ra[0]*ra[0] + pg[1]*pg[1]*ra[1]*ra[1];
779     if (d > 1.0) {
780     d = 1.0/sqrt(d);
781     pg[0] *= d;
782     pg[1] *= d;
783     }
784     }
785 greg 2.26 }
786     free(hp); /* clean up and return */
787     return(1);
788     }
789    
790    
791 greg 2.25 #else /* ! NEWAMB */
792 greg 1.1
793    
794 greg 2.15 void
795 greg 2.14 inithemi( /* initialize sampling hemisphere */
796 greg 2.23 AMBHEMI *hp,
797 greg 2.16 COLOR ac,
798 greg 2.14 RAY *r,
799     double wt
800     )
801 greg 1.1 {
802 greg 2.16 double d;
803 greg 2.23 int i;
804 greg 2.14 /* set number of divisions */
805 greg 2.16 if (ambacc <= FTINY &&
806 greg 2.20 wt > (d = 0.8*intens(ac)*r->rweight/(ambdiv*minweight)))
807 greg 2.16 wt = d; /* avoid ray termination */
808     hp->nt = sqrt(ambdiv * wt / PI) + 0.5;
809 greg 2.14 i = ambacc > FTINY ? 3 : 1; /* minimum number of samples */
810     if (hp->nt < i)
811     hp->nt = i;
812     hp->np = PI * hp->nt + 0.5;
813     /* set number of super-samples */
814 greg 2.15 hp->ns = ambssamp * wt + 0.5;
815 greg 2.16 /* assign coefficient */
816 greg 2.14 copycolor(hp->acoef, ac);
817 greg 2.16 d = 1.0/(hp->nt*hp->np);
818     scalecolor(hp->acoef, d);
819 greg 2.14 /* make axes */
820     VCOPY(hp->uz, r->ron);
821     hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
822     for (i = 0; i < 3; i++)
823     if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6)
824     break;
825     if (i >= 3)
826     error(CONSISTENCY, "bad ray direction in inithemi");
827     hp->uy[i] = 1.0;
828     fcross(hp->ux, hp->uy, hp->uz);
829     normalize(hp->ux);
830     fcross(hp->uy, hp->uz, hp->ux);
831 greg 1.1 }
832    
833    
834 greg 2.9 int
835 greg 2.14 divsample( /* sample a division */
836 greg 2.23 AMBSAMP *dp,
837 greg 2.14 AMBHEMI *h,
838     RAY *r
839     )
840 greg 1.1 {
841     RAY ar;
842 greg 1.11 int hlist[3];
843     double spt[2];
844 greg 1.1 double xd, yd, zd;
845     double b2;
846     double phi;
847 greg 2.23 int i;
848 greg 2.15 /* ambient coefficient for weight */
849 greg 2.16 if (ambacc > FTINY)
850     setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
851     else
852     copycolor(ar.rcoef, h->acoef);
853 greg 2.14 if (rayorigin(&ar, AMBIENT, r, ar.rcoef) < 0)
854 greg 1.4 return(-1);
855 greg 2.17 if (ambacc > FTINY) {
856     multcolor(ar.rcoef, h->acoef);
857     scalecolor(ar.rcoef, 1./AVGREFL);
858     }
859 greg 1.1 hlist[0] = r->rno;
860     hlist[1] = dp->t;
861     hlist[2] = dp->p;
862 greg 1.13 multisamp(spt, 2, urand(ilhash(hlist,3)+dp->n));
863 greg 1.11 zd = sqrt((dp->t + spt[0])/h->nt);
864     phi = 2.0*PI * (dp->p + spt[1])/h->np;
865 gwlarson 2.8 xd = tcos(phi) * zd;
866     yd = tsin(phi) * zd;
867 greg 1.1 zd = sqrt(1.0 - zd*zd);
868 greg 1.2 for (i = 0; i < 3; i++)
869     ar.rdir[i] = xd*h->ux[i] +
870     yd*h->uy[i] +
871     zd*h->uz[i];
872 greg 2.22 checknorm(ar.rdir);
873 greg 1.2 dimlist[ndims++] = dp->t*h->np + dp->p + 90171;
874 greg 1.1 rayvalue(&ar);
875     ndims--;
876 greg 2.16 multcolor(ar.rcol, ar.rcoef); /* apply coefficient */
877 greg 1.1 addcolor(dp->v, ar.rcol);
878 greg 2.9 /* use rt to improve gradient calc */
879     if (ar.rt > FTINY && ar.rt < FHUGE)
880     dp->r += 1.0/ar.rt;
881 greg 1.1 /* (re)initialize error */
882     if (dp->n++) {
883     b2 = bright(dp->v)/dp->n - bright(ar.rcol);
884     b2 = b2*b2 + dp->k*((dp->n-1)*(dp->n-1));
885     dp->k = b2/(dp->n*dp->n);
886     } else
887     dp->k = 0.0;
888 greg 1.4 return(0);
889 greg 1.1 }
890    
891    
892 greg 2.14 static int
893     ambcmp( /* decreasing order */
894     const void *p1,
895     const void *p2
896     )
897     {
898     const AMBSAMP *d1 = (const AMBSAMP *)p1;
899     const AMBSAMP *d2 = (const AMBSAMP *)p2;
900    
901     if (d1->k < d2->k)
902     return(1);
903     if (d1->k > d2->k)
904     return(-1);
905     return(0);
906     }
907    
908    
909     static int
910     ambnorm( /* standard order */
911     const void *p1,
912     const void *p2
913     )
914     {
915     const AMBSAMP *d1 = (const AMBSAMP *)p1;
916     const AMBSAMP *d2 = (const AMBSAMP *)p2;
917 greg 2.23 int c;
918 greg 2.14
919     if ( (c = d1->t - d2->t) )
920     return(c);
921     return(d1->p - d2->p);
922     }
923    
924    
925 greg 1.1 double
926 greg 2.14 doambient( /* compute ambient component */
927 greg 2.23 COLOR rcol,
928 greg 2.14 RAY *r,
929     double wt,
930     FVECT pg,
931     FVECT dg
932     )
933 greg 1.1 {
934 greg 2.24 double b, d=0;
935 greg 1.1 AMBHEMI hemi;
936     AMBSAMP *div;
937     AMBSAMP dnew;
938 greg 2.23 double acol[3];
939     AMBSAMP *dp;
940 greg 1.1 double arad;
941 greg 2.19 int divcnt;
942 greg 2.23 int i, j;
943 greg 1.1 /* initialize hemisphere */
944 greg 2.23 inithemi(&hemi, rcol, r, wt);
945 greg 2.19 divcnt = hemi.nt * hemi.np;
946 greg 2.17 /* initialize */
947     if (pg != NULL)
948     pg[0] = pg[1] = pg[2] = 0.0;
949     if (dg != NULL)
950     dg[0] = dg[1] = dg[2] = 0.0;
951 greg 2.23 setcolor(rcol, 0.0, 0.0, 0.0);
952 greg 2.19 if (divcnt == 0)
953 greg 1.1 return(0.0);
954 greg 2.14 /* allocate super-samples */
955 greg 2.15 if (hemi.ns > 0 || pg != NULL || dg != NULL) {
956 greg 2.19 div = (AMBSAMP *)malloc(divcnt*sizeof(AMBSAMP));
957 greg 1.1 if (div == NULL)
958     error(SYSTEM, "out of memory in doambient");
959     } else
960     div = NULL;
961     /* sample the divisions */
962     arad = 0.0;
963 greg 2.23 acol[0] = acol[1] = acol[2] = 0.0;
964 greg 1.1 if ((dp = div) == NULL)
965     dp = &dnew;
966 greg 2.19 divcnt = 0;
967 greg 1.1 for (i = 0; i < hemi.nt; i++)
968     for (j = 0; j < hemi.np; j++) {
969     dp->t = i; dp->p = j;
970     setcolor(dp->v, 0.0, 0.0, 0.0);
971 greg 1.2 dp->r = 0.0;
972 greg 1.1 dp->n = 0;
973 greg 2.16 if (divsample(dp, &hemi, r) < 0) {
974 greg 2.19 if (div != NULL)
975     dp++;
976 greg 2.16 continue;
977     }
978 greg 2.6 arad += dp->r;
979 greg 2.19 divcnt++;
980 greg 1.1 if (div != NULL)
981     dp++;
982 greg 2.6 else
983 greg 1.1 addcolor(acol, dp->v);
984     }
985 greg 2.21 if (!divcnt) {
986     if (div != NULL)
987     free((void *)div);
988 greg 2.19 return(0.0); /* no samples taken */
989 greg 2.21 }
990 greg 2.19 if (divcnt < hemi.nt*hemi.np) {
991     pg = dg = NULL; /* incomplete sampling */
992     hemi.ns = 0;
993     } else if (arad > FTINY && divcnt/arad < minarad) {
994 greg 2.15 hemi.ns = 0; /* close enough */
995 greg 2.19 } else if (hemi.ns > 0) { /* else perform super-sampling? */
996 greg 1.4 comperrs(div, &hemi); /* compute errors */
997 greg 2.19 qsort(div, divcnt, sizeof(AMBSAMP), ambcmp); /* sort divs */
998 greg 1.1 /* super-sample */
999 greg 2.15 for (i = hemi.ns; i > 0; i--) {
1000 schorsch 2.11 dnew = *div;
1001 greg 2.16 if (divsample(&dnew, &hemi, r) < 0) {
1002     dp++;
1003     continue;
1004     }
1005     dp = div; /* reinsert */
1006 greg 2.19 j = divcnt < i ? divcnt : i;
1007 greg 1.1 while (--j > 0 && dnew.k < dp[1].k) {
1008 schorsch 2.11 *dp = *(dp+1);
1009 greg 1.1 dp++;
1010     }
1011 schorsch 2.11 *dp = dnew;
1012 greg 1.1 }
1013 greg 1.2 if (pg != NULL || dg != NULL) /* restore order */
1014 greg 2.19 qsort(div, divcnt, sizeof(AMBSAMP), ambnorm);
1015 greg 1.1 }
1016     /* compute returned values */
1017 greg 1.3 if (div != NULL) {
1018 greg 2.19 arad = 0.0; /* note: divcnt may be < nt*np */
1019     for (i = hemi.nt*hemi.np, dp = div; i-- > 0; dp++) {
1020 greg 1.3 arad += dp->r;
1021     if (dp->n > 1) {
1022     b = 1.0/dp->n;
1023     scalecolor(dp->v, b);
1024     dp->r *= b;
1025     dp->n = 1;
1026     }
1027     addcolor(acol, dp->v);
1028     }
1029 greg 1.5 b = bright(acol);
1030 greg 1.6 if (b > FTINY) {
1031 greg 2.17 b = 1.0/b; /* compute & normalize gradient(s) */
1032 greg 1.6 if (pg != NULL) {
1033     posgradient(pg, div, &hemi);
1034     for (i = 0; i < 3; i++)
1035     pg[i] *= b;
1036     }
1037     if (dg != NULL) {
1038     dirgradient(dg, div, &hemi);
1039     for (i = 0; i < 3; i++)
1040     dg[i] *= b;
1041     }
1042 greg 1.5 }
1043 greg 2.9 free((void *)div);
1044 greg 1.3 }
1045 greg 2.23 copycolor(rcol, acol);
1046 greg 1.1 if (arad <= FTINY)
1047 greg 1.16 arad = maxarad;
1048 greg 2.3 else
1049 greg 2.19 arad = (divcnt+hemi.ns)/arad;
1050 greg 1.15 if (pg != NULL) { /* reduce radius if gradient large */
1051     d = DOT(pg,pg);
1052     if (d*arad*arad > 1.0)
1053     arad = 1.0/sqrt(d);
1054     }
1055 greg 1.16 if (arad < minarad) {
1056 greg 1.1 arad = minarad;
1057 greg 1.16 if (pg != NULL && d*arad*arad > 1.0) { /* cap gradient */
1058     d = 1.0/arad/sqrt(d);
1059     for (i = 0; i < 3; i++)
1060     pg[i] *= d;
1061     }
1062     }
1063 greg 2.3 if ((arad /= sqrt(wt)) > maxarad)
1064     arad = maxarad;
1065     return(arad);
1066 greg 1.1 }
1067    
1068    
1069 greg 2.9 void
1070 greg 2.14 comperrs( /* compute initial error estimates */
1071     AMBSAMP *da, /* assumes standard ordering */
1072 greg 2.23 AMBHEMI *hp
1073 greg 2.14 )
1074 greg 1.1 {
1075     double b, b2;
1076     int i, j;
1077 greg 2.23 AMBSAMP *dp;
1078 greg 1.1 /* sum differences from neighbors */
1079     dp = da;
1080     for (i = 0; i < hp->nt; i++)
1081     for (j = 0; j < hp->np; j++) {
1082 greg 1.6 #ifdef DEBUG
1083     if (dp->t != i || dp->p != j)
1084     error(CONSISTENCY,
1085     "division order in comperrs");
1086     #endif
1087 greg 1.1 b = bright(dp[0].v);
1088     if (i > 0) { /* from above */
1089     b2 = bright(dp[-hp->np].v) - b;
1090     b2 *= b2 * 0.25;
1091     dp[0].k += b2;
1092     dp[-hp->np].k += b2;
1093     }
1094     if (j > 0) { /* from behind */
1095     b2 = bright(dp[-1].v) - b;
1096     b2 *= b2 * 0.25;
1097     dp[0].k += b2;
1098     dp[-1].k += b2;
1099 greg 1.4 } else { /* around */
1100     b2 = bright(dp[hp->np-1].v) - b;
1101 greg 1.1 b2 *= b2 * 0.25;
1102     dp[0].k += b2;
1103 greg 1.4 dp[hp->np-1].k += b2;
1104 greg 1.1 }
1105     dp++;
1106     }
1107     /* divide by number of neighbors */
1108     dp = da;
1109     for (j = 0; j < hp->np; j++) /* top row */
1110     (dp++)->k *= 1.0/3.0;
1111     if (hp->nt < 2)
1112     return;
1113     for (i = 1; i < hp->nt-1; i++) /* central region */
1114     for (j = 0; j < hp->np; j++)
1115     (dp++)->k *= 0.25;
1116     for (j = 0; j < hp->np; j++) /* bottom row */
1117     (dp++)->k *= 1.0/3.0;
1118     }
1119    
1120    
1121 greg 2.9 void
1122 greg 2.14 posgradient( /* compute position gradient */
1123     FVECT gv,
1124     AMBSAMP *da, /* assumes standard ordering */
1125 greg 2.23 AMBHEMI *hp
1126 greg 2.14 )
1127 greg 1.1 {
1128 greg 2.23 int i, j;
1129 greg 2.2 double nextsine, lastsine, b, d;
1130 greg 1.2 double mag0, mag1;
1131     double phi, cosp, sinp, xd, yd;
1132 greg 2.23 AMBSAMP *dp;
1133 greg 1.2
1134     xd = yd = 0.0;
1135     for (j = 0; j < hp->np; j++) {
1136     dp = da + j;
1137     mag0 = mag1 = 0.0;
1138 greg 2.2 lastsine = 0.0;
1139 greg 1.2 for (i = 0; i < hp->nt; i++) {
1140     #ifdef DEBUG
1141     if (dp->t != i || dp->p != j)
1142     error(CONSISTENCY,
1143     "division order in posgradient");
1144     #endif
1145     b = bright(dp->v);
1146     if (i > 0) {
1147     d = dp[-hp->np].r;
1148     if (dp[0].r > d) d = dp[0].r;
1149 greg 2.2 /* sin(t)*cos(t)^2 */
1150     d *= lastsine * (1.0 - (double)i/hp->nt);
1151 greg 1.2 mag0 += d*(b - bright(dp[-hp->np].v));
1152     }
1153 greg 2.2 nextsine = sqrt((double)(i+1)/hp->nt);
1154 greg 1.2 if (j > 0) {
1155     d = dp[-1].r;
1156     if (dp[0].r > d) d = dp[0].r;
1157 greg 2.2 mag1 += d * (nextsine - lastsine) *
1158     (b - bright(dp[-1].v));
1159 greg 1.2 } else {
1160     d = dp[hp->np-1].r;
1161     if (dp[0].r > d) d = dp[0].r;
1162 greg 2.2 mag1 += d * (nextsine - lastsine) *
1163     (b - bright(dp[hp->np-1].v));
1164 greg 1.2 }
1165     dp += hp->np;
1166 greg 2.2 lastsine = nextsine;
1167 greg 1.2 }
1168 greg 2.2 mag0 *= 2.0*PI / hp->np;
1169 greg 1.2 phi = 2.0*PI * (double)j/hp->np;
1170 gwlarson 2.8 cosp = tcos(phi); sinp = tsin(phi);
1171 greg 1.2 xd += mag0*cosp - mag1*sinp;
1172     yd += mag0*sinp + mag1*cosp;
1173     }
1174     for (i = 0; i < 3; i++)
1175 greg 2.16 gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])*(hp->nt*hp->np)/PI;
1176 greg 1.1 }
1177    
1178    
1179 greg 2.9 void
1180 greg 2.14 dirgradient( /* compute direction gradient */
1181     FVECT gv,
1182     AMBSAMP *da, /* assumes standard ordering */
1183 greg 2.23 AMBHEMI *hp
1184 greg 2.14 )
1185 greg 1.1 {
1186 greg 2.23 int i, j;
1187 greg 1.2 double mag;
1188     double phi, xd, yd;
1189 greg 2.23 AMBSAMP *dp;
1190 greg 1.2
1191     xd = yd = 0.0;
1192     for (j = 0; j < hp->np; j++) {
1193     dp = da + j;
1194     mag = 0.0;
1195     for (i = 0; i < hp->nt; i++) {
1196     #ifdef DEBUG
1197     if (dp->t != i || dp->p != j)
1198     error(CONSISTENCY,
1199     "division order in dirgradient");
1200     #endif
1201 greg 2.2 /* tan(t) */
1202     mag += bright(dp->v)/sqrt(hp->nt/(i+.5) - 1.0);
1203 greg 1.2 dp += hp->np;
1204     }
1205     phi = 2.0*PI * (j+.5)/hp->np + PI/2.0;
1206 gwlarson 2.8 xd += mag * tcos(phi);
1207     yd += mag * tsin(phi);
1208 greg 1.2 }
1209     for (i = 0; i < 3; i++)
1210 greg 2.16 gv[i] = xd*hp->ux[i] + yd*hp->uy[i];
1211 greg 1.1 }
1212 greg 2.25
1213     #endif /* ! NEWAMB */