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root/radiance/ray/src/rt/ambcomp.c
Revision: 2.78
Committed: Tue Jan 9 00:51:51 2018 UTC (6 years, 4 months ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 2.77: +8 -2 lines
Log Message:
Attempt to fix issue with low-angle ambient through trans and the like

File Contents

# User Rev Content
1 greg 1.1 #ifndef lint
2 greg 2.78 static const char RCSid[] = "$Id: ambcomp.c,v 2.77 2017/04/21 16:07:29 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 2.78 #include "source.h"
24     #include "otypes.h"
25     #include "otspecial.h"
26 greg 1.1
27 greg 2.63 #ifndef OLDAMB
28 greg 1.1
29 greg 2.26 extern void SDsquare2disk(double ds[2], double seedx, double seedy);
30    
31     typedef struct {
32 greg 2.44 COLOR v; /* hemisphere sample value */
33 greg 2.47 float d; /* reciprocal distance (1/rt) */
34 greg 2.44 FVECT p; /* intersection point */
35     } AMBSAMP; /* sample value */
36    
37     typedef struct {
38 greg 2.26 RAY *rp; /* originating ray sample */
39     int ns; /* number of samples per axis */
40 greg 2.61 int sampOK; /* acquired full sample set? */
41 greg 2.26 COLOR acoef; /* division contribution coefficient */
42 greg 2.61 double acol[3]; /* accumulated color */
43     FVECT ux, uy; /* tangent axis unit vectors */
44 greg 2.44 AMBSAMP sa[1]; /* sample array (extends struct) */
45 greg 2.26 } AMBHEMI; /* ambient sample hemisphere */
46    
47 greg 2.56 #define AI(h,i,j) ((i)*(h)->ns + (j))
48     #define ambsam(h,i,j) (h)->sa[AI(h,i,j)]
49 greg 2.26
50 greg 2.27 typedef struct {
51 greg 2.35 FVECT r_i, r_i1, e_i, rcp, rI2_eJ2;
52     double I1, I2;
53 greg 2.27 } FFTRI; /* vectors and coefficients for Hessian calculation */
54    
55 greg 2.26
56 greg 2.61 static int
57 greg 2.73 ambcollision( /* proposed direciton collides? */
58     AMBHEMI *hp,
59     int i,
60     int j,
61     FVECT dv
62     )
63     {
64 greg 2.74 double cos_thresh;
65     int ii, jj;
66 greg 2.75 /* min. spacing = 1/4th division */
67     cos_thresh = (PI/4.)/(double)hp->ns;
68 greg 2.74 cos_thresh = 1. - .5*cos_thresh*cos_thresh;
69     /* check existing neighbors */
70 greg 2.73 for (ii = i-1; ii <= i+1; ii++) {
71     if (ii < 0) continue;
72     if (ii >= hp->ns) break;
73     for (jj = j-1; jj <= j+1; jj++) {
74     AMBSAMP *ap;
75     FVECT avec;
76     double dprod;
77     if (jj < 0) continue;
78     if (jj >= hp->ns) break;
79     if ((ii==i) & (jj==j)) continue;
80     ap = &ambsam(hp,ii,jj);
81 greg 2.74 if (ap->d <= .5/FHUGE)
82     continue; /* no one home */
83 greg 2.73 VSUB(avec, ap->p, hp->rp->rop);
84     dprod = DOT(avec, dv);
85     if (dprod >= cos_thresh*VLEN(avec))
86     return(1); /* collision */
87     }
88     }
89 greg 2.74 return(0); /* nothing to worry about */
90 greg 2.73 }
91    
92    
93     static int
94 greg 2.61 ambsample( /* initial ambient division sample */
95     AMBHEMI *hp,
96     int i,
97     int j,
98     int n
99 greg 2.26 )
100     {
101 greg 2.61 AMBSAMP *ap = &ambsam(hp,i,j);
102     RAY ar;
103 greg 2.41 int hlist[3], ii;
104     double spt[2], zd;
105 greg 2.61 /* generate hemispherical sample */
106 greg 2.26 /* ambient coefficient for weight */
107     if (ambacc > FTINY)
108 greg 2.61 setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
109 greg 2.26 else
110 greg 2.61 copycolor(ar.rcoef, hp->acoef);
111 greg 2.62 if (rayorigin(&ar, AMBIENT, hp->rp, ar.rcoef) < 0)
112 greg 2.41 return(0);
113 greg 2.26 if (ambacc > FTINY) {
114 greg 2.61 multcolor(ar.rcoef, hp->acoef);
115     scalecolor(ar.rcoef, 1./AVGREFL);
116 greg 2.41 }
117     hlist[0] = hp->rp->rno;
118 greg 2.46 hlist[1] = j;
119     hlist[2] = i;
120 greg 2.41 multisamp(spt, 2, urand(ilhash(hlist,3)+n));
121 greg 2.73 resample:
122 greg 2.46 SDsquare2disk(spt, (j+spt[1])/hp->ns, (i+spt[0])/hp->ns);
123 greg 2.26 zd = sqrt(1. - spt[0]*spt[0] - spt[1]*spt[1]);
124     for (ii = 3; ii--; )
125 greg 2.61 ar.rdir[ii] = spt[0]*hp->ux[ii] +
126 greg 2.26 spt[1]*hp->uy[ii] +
127     zd*hp->rp->ron[ii];
128 greg 2.61 checknorm(ar.rdir);
129 greg 2.73 /* avoid coincident samples */
130     if (!n && ambcollision(hp, i, j, ar.rdir)) {
131     spt[0] = frandom(); spt[1] = frandom();
132 greg 2.75 goto resample; /* reject this sample */
133 greg 2.73 }
134 greg 2.56 dimlist[ndims++] = AI(hp,i,j) + 90171;
135 greg 2.61 rayvalue(&ar); /* evaluate ray */
136     ndims--;
137     if (ar.rt <= FTINY)
138     return(0); /* should never happen */
139     multcolor(ar.rcol, ar.rcoef); /* apply coefficient */
140 greg 2.62 if (ar.rt*ap->d < 1.0) /* new/closer distance? */
141 greg 2.61 ap->d = 1.0/ar.rt;
142     if (!n) { /* record first vertex & value */
143 greg 2.76 if (ar.rt > 10.0*thescene.cusize + 1000.)
144     ar.rt = 10.0*thescene.cusize + 1000.;
145 greg 2.61 VSUM(ap->p, ar.rorg, ar.rdir, ar.rt);
146     copycolor(ap->v, ar.rcol);
147     } else { /* else update recorded value */
148     hp->acol[RED] -= colval(ap->v,RED);
149     hp->acol[GRN] -= colval(ap->v,GRN);
150     hp->acol[BLU] -= colval(ap->v,BLU);
151     zd = 1.0/(double)(n+1);
152     scalecolor(ar.rcol, zd);
153     zd *= (double)n;
154     scalecolor(ap->v, zd);
155     addcolor(ap->v, ar.rcol);
156     }
157     addcolor(hp->acol, ap->v); /* add to our sum */
158 greg 2.41 return(1);
159     }
160    
161    
162     /* Estimate errors based on ambient division differences */
163     static float *
164     getambdiffs(AMBHEMI *hp)
165     {
166 greg 2.77 const double normf = 1./bright(hp->acoef);
167 greg 2.55 float *earr = (float *)calloc(hp->ns*hp->ns, sizeof(float));
168 greg 2.41 float *ep;
169 greg 2.42 AMBSAMP *ap;
170 greg 2.41 double b, d2;
171     int i, j;
172    
173     if (earr == NULL) /* out of memory? */
174     return(NULL);
175     /* compute squared neighbor diffs */
176 greg 2.42 for (ap = hp->sa, ep = earr, i = 0; i < hp->ns; i++)
177     for (j = 0; j < hp->ns; j++, ap++, ep++) {
178     b = bright(ap[0].v);
179 greg 2.41 if (i) { /* from above */
180 greg 2.77 d2 = normf*(b - bright(ap[-hp->ns].v));
181 greg 2.41 d2 *= d2;
182     ep[0] += d2;
183     ep[-hp->ns] += d2;
184     }
185 greg 2.55 if (!j) continue;
186     /* from behind */
187 greg 2.77 d2 = normf*(b - bright(ap[-1].v));
188 greg 2.55 d2 *= d2;
189     ep[0] += d2;
190     ep[-1] += d2;
191     if (!i) continue;
192     /* diagonal */
193 greg 2.77 d2 = normf*(b - bright(ap[-hp->ns-1].v));
194 greg 2.55 d2 *= d2;
195     ep[0] += d2;
196     ep[-hp->ns-1] += d2;
197 greg 2.41 }
198     /* correct for number of neighbors */
199 greg 2.55 earr[0] *= 8./3.;
200     earr[hp->ns-1] *= 8./3.;
201     earr[(hp->ns-1)*hp->ns] *= 8./3.;
202     earr[(hp->ns-1)*hp->ns + hp->ns-1] *= 8./3.;
203 greg 2.41 for (i = 1; i < hp->ns-1; i++) {
204 greg 2.55 earr[i*hp->ns] *= 8./5.;
205     earr[i*hp->ns + hp->ns-1] *= 8./5.;
206 greg 2.41 }
207     for (j = 1; j < hp->ns-1; j++) {
208 greg 2.55 earr[j] *= 8./5.;
209     earr[(hp->ns-1)*hp->ns + j] *= 8./5.;
210 greg 2.41 }
211     return(earr);
212     }
213    
214    
215 greg 2.43 /* Perform super-sampling on hemisphere (introduces bias) */
216 greg 2.41 static void
217 greg 2.61 ambsupersamp(AMBHEMI *hp, int cnt)
218 greg 2.41 {
219     float *earr = getambdiffs(hp);
220 greg 2.54 double e2rem = 0;
221 greg 2.41 AMBSAMP *ap;
222     float *ep;
223 greg 2.55 int i, j, n, nss;
224 greg 2.41
225     if (earr == NULL) /* just skip calc. if no memory */
226     return;
227 greg 2.54 /* accumulate estimated variances */
228 greg 2.55 for (ep = earr + hp->ns*hp->ns; ep > earr; )
229     e2rem += *--ep;
230 greg 2.41 ep = earr; /* perform super-sampling */
231     for (ap = hp->sa, i = 0; i < hp->ns; i++)
232     for (j = 0; j < hp->ns; j++, ap++) {
233 greg 2.55 if (e2rem <= FTINY)
234     goto done; /* nothing left to do */
235     nss = *ep/e2rem*cnt + frandom();
236 greg 2.62 for (n = 1; n <= nss && ambsample(hp,i,j,n); n++)
237 greg 2.77 if (!--cnt) goto done;
238 greg 2.61 e2rem -= *ep++; /* update remainder */
239 greg 2.41 }
240 greg 2.55 done:
241 greg 2.41 free(earr);
242     }
243    
244    
245 greg 2.61 static AMBHEMI *
246     samp_hemi( /* sample indirect hemisphere */
247     COLOR rcol,
248     RAY *r,
249     double wt
250     )
251     {
252     AMBHEMI *hp;
253     double d;
254     int n, i, j;
255 greg 2.77 /* insignificance check */
256     if (bright(rcol) <= FTINY)
257     return(NULL);
258 greg 2.61 /* set number of divisions */
259     if (ambacc <= FTINY &&
260     wt > (d = 0.8*intens(rcol)*r->rweight/(ambdiv*minweight)))
261     wt = d; /* avoid ray termination */
262     n = sqrt(ambdiv * wt) + 0.5;
263 greg 2.68 i = 1 + 5*(ambacc > FTINY); /* minimum number of samples */
264 greg 2.61 if (n < i)
265     n = i;
266     /* allocate sampling array */
267     hp = (AMBHEMI *)malloc(sizeof(AMBHEMI) + sizeof(AMBSAMP)*(n*n - 1));
268     if (hp == NULL)
269     error(SYSTEM, "out of memory in samp_hemi");
270     hp->rp = r;
271     hp->ns = n;
272     hp->acol[RED] = hp->acol[GRN] = hp->acol[BLU] = 0.0;
273 greg 2.62 memset(hp->sa, 0, sizeof(AMBSAMP)*n*n);
274 greg 2.61 hp->sampOK = 0;
275     /* assign coefficient */
276     copycolor(hp->acoef, rcol);
277     d = 1.0/(n*n);
278     scalecolor(hp->acoef, d);
279     /* make tangent plane axes */
280 greg 2.70 if (!getperpendicular(hp->ux, r->ron, 1))
281 greg 2.61 error(CONSISTENCY, "bad ray direction in samp_hemi");
282     VCROSS(hp->uy, r->ron, hp->ux);
283     /* sample divisions */
284     for (i = hp->ns; i--; )
285     for (j = hp->ns; j--; )
286     hp->sampOK += ambsample(hp, i, j, 0);
287     copycolor(rcol, hp->acol);
288     if (!hp->sampOK) { /* utter failure? */
289     free(hp);
290     return(NULL);
291     }
292     if (hp->sampOK < hp->ns*hp->ns) {
293     hp->sampOK *= -1; /* soft failure */
294     return(hp);
295     }
296     n = ambssamp*wt + 0.5;
297     if (n > 8) { /* perform super-sampling? */
298     ambsupersamp(hp, n);
299     copycolor(rcol, hp->acol);
300     }
301     return(hp); /* all is well */
302     }
303    
304    
305 greg 2.46 /* Return brightness of farthest ambient sample */
306     static double
307 greg 2.56 back_ambval(AMBHEMI *hp, const int n1, const int n2, const int n3)
308 greg 2.46 {
309 greg 2.56 if (hp->sa[n1].d <= hp->sa[n2].d) {
310     if (hp->sa[n1].d <= hp->sa[n3].d)
311     return(colval(hp->sa[n1].v,CIEY));
312     return(colval(hp->sa[n3].v,CIEY));
313     }
314     if (hp->sa[n2].d <= hp->sa[n3].d)
315     return(colval(hp->sa[n2].v,CIEY));
316     return(colval(hp->sa[n3].v,CIEY));
317 greg 2.46 }
318    
319    
320 greg 2.27 /* Compute vectors and coefficients for Hessian/gradient calcs */
321     static void
322 greg 2.56 comp_fftri(FFTRI *ftp, AMBHEMI *hp, const int n0, const int n1)
323 greg 2.27 {
324 greg 2.56 double rdot_cp, dot_e, dot_er, rdot_r, rdot_r1, J2;
325     int ii;
326    
327     VSUB(ftp->r_i, hp->sa[n0].p, hp->rp->rop);
328     VSUB(ftp->r_i1, hp->sa[n1].p, hp->rp->rop);
329     VSUB(ftp->e_i, hp->sa[n1].p, hp->sa[n0].p);
330 greg 2.35 VCROSS(ftp->rcp, ftp->r_i, ftp->r_i1);
331     rdot_cp = 1.0/DOT(ftp->rcp,ftp->rcp);
332 greg 2.27 dot_e = DOT(ftp->e_i,ftp->e_i);
333     dot_er = DOT(ftp->e_i, ftp->r_i);
334 greg 2.32 rdot_r = 1.0/DOT(ftp->r_i,ftp->r_i);
335     rdot_r1 = 1.0/DOT(ftp->r_i1,ftp->r_i1);
336     ftp->I1 = acos( DOT(ftp->r_i, ftp->r_i1) * sqrt(rdot_r*rdot_r1) ) *
337 greg 2.35 sqrt( rdot_cp );
338 greg 2.32 ftp->I2 = ( DOT(ftp->e_i, ftp->r_i1)*rdot_r1 - dot_er*rdot_r +
339 greg 2.35 dot_e*ftp->I1 )*0.5*rdot_cp;
340 greg 2.32 J2 = ( 0.5*(rdot_r - rdot_r1) - dot_er*ftp->I2 ) / dot_e;
341 greg 2.46 for (ii = 3; ii--; )
342     ftp->rI2_eJ2[ii] = ftp->I2*ftp->r_i[ii] + J2*ftp->e_i[ii];
343 greg 2.27 }
344    
345    
346 greg 2.28 /* Compose 3x3 matrix from two vectors */
347 greg 2.27 static void
348     compose_matrix(FVECT mat[3], FVECT va, FVECT vb)
349     {
350     mat[0][0] = 2.0*va[0]*vb[0];
351     mat[1][1] = 2.0*va[1]*vb[1];
352     mat[2][2] = 2.0*va[2]*vb[2];
353     mat[0][1] = mat[1][0] = va[0]*vb[1] + va[1]*vb[0];
354     mat[0][2] = mat[2][0] = va[0]*vb[2] + va[2]*vb[0];
355     mat[1][2] = mat[2][1] = va[1]*vb[2] + va[2]*vb[1];
356     }
357    
358    
359     /* Compute partial 3x3 Hessian matrix for edge */
360     static void
361     comp_hessian(FVECT hess[3], FFTRI *ftp, FVECT nrm)
362     {
363 greg 2.35 FVECT ncp;
364 greg 2.27 FVECT m1[3], m2[3], m3[3], m4[3];
365     double d1, d2, d3, d4;
366     double I3, J3, K3;
367     int i, j;
368     /* compute intermediate coefficients */
369     d1 = 1.0/DOT(ftp->r_i,ftp->r_i);
370     d2 = 1.0/DOT(ftp->r_i1,ftp->r_i1);
371     d3 = 1.0/DOT(ftp->e_i,ftp->e_i);
372     d4 = DOT(ftp->e_i, ftp->r_i);
373 greg 2.35 I3 = ( DOT(ftp->e_i, ftp->r_i1)*d2*d2 - d4*d1*d1 + 3.0/d3*ftp->I2 )
374     / ( 4.0*DOT(ftp->rcp,ftp->rcp) );
375 greg 2.27 J3 = 0.25*d3*(d1*d1 - d2*d2) - d4*d3*I3;
376     K3 = d3*(ftp->I2 - I3/d1 - 2.0*d4*J3);
377     /* intermediate matrices */
378 greg 2.35 VCROSS(ncp, nrm, ftp->e_i);
379     compose_matrix(m1, ncp, ftp->rI2_eJ2);
380 greg 2.27 compose_matrix(m2, ftp->r_i, ftp->r_i);
381     compose_matrix(m3, ftp->e_i, ftp->e_i);
382     compose_matrix(m4, ftp->r_i, ftp->e_i);
383 greg 2.35 d1 = DOT(nrm, ftp->rcp);
384 greg 2.27 d2 = -d1*ftp->I2;
385     d1 *= 2.0;
386     for (i = 3; i--; ) /* final matrix sum */
387     for (j = 3; j--; ) {
388     hess[i][j] = m1[i][j] + d1*( I3*m2[i][j] + K3*m3[i][j] +
389     2.0*J3*m4[i][j] );
390     hess[i][j] += d2*(i==j);
391 greg 2.46 hess[i][j] *= -1.0/PI;
392 greg 2.27 }
393     }
394    
395    
396     /* Reverse hessian calculation result for edge in other direction */
397     static void
398     rev_hessian(FVECT hess[3])
399     {
400     int i;
401    
402     for (i = 3; i--; ) {
403     hess[i][0] = -hess[i][0];
404     hess[i][1] = -hess[i][1];
405     hess[i][2] = -hess[i][2];
406     }
407     }
408    
409    
410     /* Add to radiometric Hessian from the given triangle */
411     static void
412     add2hessian(FVECT hess[3], FVECT ehess1[3],
413 greg 2.46 FVECT ehess2[3], FVECT ehess3[3], double v)
414 greg 2.27 {
415     int i, j;
416    
417     for (i = 3; i--; )
418     for (j = 3; j--; )
419     hess[i][j] += v*( ehess1[i][j] + ehess2[i][j] + ehess3[i][j] );
420     }
421    
422    
423     /* Compute partial displacement form factor gradient for edge */
424     static void
425     comp_gradient(FVECT grad, FFTRI *ftp, FVECT nrm)
426     {
427 greg 2.35 FVECT ncp;
428 greg 2.27 double f1;
429     int i;
430    
431 greg 2.35 f1 = 2.0*DOT(nrm, ftp->rcp);
432     VCROSS(ncp, nrm, ftp->e_i);
433 greg 2.27 for (i = 3; i--; )
434 greg 2.46 grad[i] = (0.5/PI)*( ftp->I1*ncp[i] + f1*ftp->rI2_eJ2[i] );
435 greg 2.27 }
436    
437    
438     /* Reverse gradient calculation result for edge in other direction */
439     static void
440     rev_gradient(FVECT grad)
441     {
442     grad[0] = -grad[0];
443     grad[1] = -grad[1];
444     grad[2] = -grad[2];
445     }
446    
447    
448     /* Add to displacement gradient from the given triangle */
449     static void
450 greg 2.46 add2gradient(FVECT grad, FVECT egrad1, FVECT egrad2, FVECT egrad3, double v)
451 greg 2.27 {
452     int i;
453    
454     for (i = 3; i--; )
455     grad[i] += v*( egrad1[i] + egrad2[i] + egrad3[i] );
456     }
457    
458    
459     /* Compute anisotropic radii and eigenvector directions */
460 greg 2.53 static void
461 greg 2.27 eigenvectors(FVECT uv[2], float ra[2], FVECT hessian[3])
462     {
463     double hess2[2][2];
464     FVECT a, b;
465     double evalue[2], slope1, xmag1;
466     int i;
467     /* project Hessian to sample plane */
468     for (i = 3; i--; ) {
469     a[i] = DOT(hessian[i], uv[0]);
470     b[i] = DOT(hessian[i], uv[1]);
471     }
472     hess2[0][0] = DOT(uv[0], a);
473     hess2[0][1] = DOT(uv[0], b);
474     hess2[1][0] = DOT(uv[1], a);
475     hess2[1][1] = DOT(uv[1], b);
476 greg 2.38 /* compute eigenvalue(s) */
477     i = quadratic(evalue, 1.0, -hess2[0][0]-hess2[1][1],
478     hess2[0][0]*hess2[1][1]-hess2[0][1]*hess2[1][0]);
479     if (i == 1) /* double-root (circle) */
480     evalue[1] = evalue[0];
481     if (!i || ((evalue[0] = fabs(evalue[0])) <= FTINY*FTINY) |
482 greg 2.53 ((evalue[1] = fabs(evalue[1])) <= FTINY*FTINY) ) {
483     ra[0] = ra[1] = maxarad;
484     return;
485     }
486 greg 2.27 if (evalue[0] > evalue[1]) {
487 greg 2.29 ra[0] = sqrt(sqrt(4.0/evalue[0]));
488     ra[1] = sqrt(sqrt(4.0/evalue[1]));
489 greg 2.27 slope1 = evalue[1];
490     } else {
491 greg 2.29 ra[0] = sqrt(sqrt(4.0/evalue[1]));
492     ra[1] = sqrt(sqrt(4.0/evalue[0]));
493 greg 2.27 slope1 = evalue[0];
494     }
495     /* compute unit eigenvectors */
496     if (fabs(hess2[0][1]) <= FTINY)
497     return; /* uv OK as is */
498     slope1 = (slope1 - hess2[0][0]) / hess2[0][1];
499     xmag1 = sqrt(1.0/(1.0 + slope1*slope1));
500     for (i = 3; i--; ) {
501     b[i] = xmag1*uv[0][i] + slope1*xmag1*uv[1][i];
502     a[i] = slope1*xmag1*uv[0][i] - xmag1*uv[1][i];
503     }
504     VCOPY(uv[0], a);
505     VCOPY(uv[1], b);
506     }
507    
508    
509 greg 2.26 static void
510     ambHessian( /* anisotropic radii & pos. gradient */
511     AMBHEMI *hp,
512     FVECT uv[2], /* returned */
513 greg 2.28 float ra[2], /* returned (optional) */
514     float pg[2] /* returned (optional) */
515 greg 2.26 )
516     {
517 greg 2.27 static char memerrmsg[] = "out of memory in ambHessian()";
518     FVECT (*hessrow)[3] = NULL;
519     FVECT *gradrow = NULL;
520     FVECT hessian[3];
521     FVECT gradient;
522     FFTRI fftr;
523     int i, j;
524     /* be sure to assign unit vectors */
525     VCOPY(uv[0], hp->ux);
526     VCOPY(uv[1], hp->uy);
527     /* clock-wise vertex traversal from sample POV */
528     if (ra != NULL) { /* initialize Hessian row buffer */
529 greg 2.28 hessrow = (FVECT (*)[3])malloc(sizeof(FVECT)*3*(hp->ns-1));
530 greg 2.27 if (hessrow == NULL)
531     error(SYSTEM, memerrmsg);
532     memset(hessian, 0, sizeof(hessian));
533     } else if (pg == NULL) /* bogus call? */
534     return;
535     if (pg != NULL) { /* initialize form factor row buffer */
536 greg 2.28 gradrow = (FVECT *)malloc(sizeof(FVECT)*(hp->ns-1));
537 greg 2.27 if (gradrow == NULL)
538     error(SYSTEM, memerrmsg);
539     memset(gradient, 0, sizeof(gradient));
540     }
541     /* compute first row of edges */
542     for (j = 0; j < hp->ns-1; j++) {
543 greg 2.56 comp_fftri(&fftr, hp, AI(hp,0,j), AI(hp,0,j+1));
544 greg 2.27 if (hessrow != NULL)
545     comp_hessian(hessrow[j], &fftr, hp->rp->ron);
546     if (gradrow != NULL)
547     comp_gradient(gradrow[j], &fftr, hp->rp->ron);
548     }
549     /* sum each row of triangles */
550     for (i = 0; i < hp->ns-1; i++) {
551     FVECT hesscol[3]; /* compute first vertical edge */
552     FVECT gradcol;
553 greg 2.56 comp_fftri(&fftr, hp, AI(hp,i,0), AI(hp,i+1,0));
554 greg 2.27 if (hessrow != NULL)
555     comp_hessian(hesscol, &fftr, hp->rp->ron);
556     if (gradrow != NULL)
557     comp_gradient(gradcol, &fftr, hp->rp->ron);
558     for (j = 0; j < hp->ns-1; j++) {
559     FVECT hessdia[3]; /* compute triangle contributions */
560     FVECT graddia;
561 greg 2.46 double backg;
562 greg 2.56 backg = back_ambval(hp, AI(hp,i,j),
563     AI(hp,i,j+1), AI(hp,i+1,j));
564 greg 2.27 /* diagonal (inner) edge */
565 greg 2.56 comp_fftri(&fftr, hp, AI(hp,i,j+1), AI(hp,i+1,j));
566 greg 2.27 if (hessrow != NULL) {
567     comp_hessian(hessdia, &fftr, hp->rp->ron);
568     rev_hessian(hesscol);
569     add2hessian(hessian, hessrow[j], hessdia, hesscol, backg);
570     }
571 greg 2.39 if (gradrow != NULL) {
572 greg 2.27 comp_gradient(graddia, &fftr, hp->rp->ron);
573     rev_gradient(gradcol);
574     add2gradient(gradient, gradrow[j], graddia, gradcol, backg);
575     }
576     /* initialize edge in next row */
577 greg 2.56 comp_fftri(&fftr, hp, AI(hp,i+1,j+1), AI(hp,i+1,j));
578 greg 2.27 if (hessrow != NULL)
579     comp_hessian(hessrow[j], &fftr, hp->rp->ron);
580     if (gradrow != NULL)
581     comp_gradient(gradrow[j], &fftr, hp->rp->ron);
582     /* new column edge & paired triangle */
583 greg 2.56 backg = back_ambval(hp, AI(hp,i+1,j+1),
584     AI(hp,i+1,j), AI(hp,i,j+1));
585     comp_fftri(&fftr, hp, AI(hp,i,j+1), AI(hp,i+1,j+1));
586 greg 2.27 if (hessrow != NULL) {
587     comp_hessian(hesscol, &fftr, hp->rp->ron);
588     rev_hessian(hessdia);
589     add2hessian(hessian, hessrow[j], hessdia, hesscol, backg);
590     if (i < hp->ns-2)
591     rev_hessian(hessrow[j]);
592     }
593     if (gradrow != NULL) {
594     comp_gradient(gradcol, &fftr, hp->rp->ron);
595     rev_gradient(graddia);
596     add2gradient(gradient, gradrow[j], graddia, gradcol, backg);
597     if (i < hp->ns-2)
598     rev_gradient(gradrow[j]);
599     }
600     }
601     }
602     /* release row buffers */
603     if (hessrow != NULL) free(hessrow);
604     if (gradrow != NULL) free(gradrow);
605    
606     if (ra != NULL) /* extract eigenvectors & radii */
607     eigenvectors(uv, ra, hessian);
608 greg 2.32 if (pg != NULL) { /* tangential position gradient */
609     pg[0] = DOT(gradient, uv[0]);
610     pg[1] = DOT(gradient, uv[1]);
611 greg 2.27 }
612     }
613    
614    
615     /* Compute direction gradient from a hemispherical sampling */
616     static void
617     ambdirgrad(AMBHEMI *hp, FVECT uv[2], float dg[2])
618     {
619 greg 2.41 AMBSAMP *ap;
620     double dgsum[2];
621     int n;
622     FVECT vd;
623     double gfact;
624 greg 2.27
625 greg 2.29 dgsum[0] = dgsum[1] = 0.0; /* sum values times -tan(theta) */
626 greg 2.27 for (ap = hp->sa, n = hp->ns*hp->ns; n--; ap++) {
627     /* use vector for azimuth + 90deg */
628     VSUB(vd, ap->p, hp->rp->rop);
629 greg 2.29 /* brightness over cosine factor */
630     gfact = colval(ap->v,CIEY) / DOT(hp->rp->ron, vd);
631 greg 2.40 /* sine = proj_radius/vd_length */
632     dgsum[0] -= DOT(uv[1], vd) * gfact;
633     dgsum[1] += DOT(uv[0], vd) * gfact;
634 greg 2.26 }
635 greg 2.29 dg[0] = dgsum[0] / (hp->ns*hp->ns);
636     dg[1] = dgsum[1] / (hp->ns*hp->ns);
637 greg 2.26 }
638    
639 greg 2.27
640 greg 2.49 /* Compute potential light leak direction flags for cache value */
641     static uint32
642     ambcorral(AMBHEMI *hp, FVECT uv[2], const double r0, const double r1)
643 greg 2.47 {
644 greg 2.50 const double max_d = 1.0/(minarad*ambacc + 0.001);
645 greg 2.66 const double ang_res = 0.5*PI/hp->ns;
646     const double ang_step = ang_res/((int)(16/PI*ang_res) + 1.01);
647 greg 2.51 double avg_d = 0;
648 greg 2.50 uint32 flgs = 0;
649 greg 2.58 FVECT vec;
650 greg 2.62 double u, v;
651 greg 2.58 double ang, a1;
652 greg 2.78 OBJREC *m;
653 greg 2.50 int i, j;
654 greg 2.52 /* don't bother for a few samples */
655 greg 2.72 if (hp->ns < 8)
656 greg 2.52 return(0);
657     /* check distances overhead */
658 greg 2.51 for (i = hp->ns*3/4; i-- > hp->ns>>2; )
659     for (j = hp->ns*3/4; j-- > hp->ns>>2; )
660     avg_d += ambsam(hp,i,j).d;
661     avg_d *= 4.0/(hp->ns*hp->ns);
662 greg 2.52 if (avg_d*r0 >= 1.0) /* ceiling too low for corral? */
663     return(0);
664     if (avg_d >= max_d) /* insurance */
665 greg 2.51 return(0);
666     /* else circle around perimeter */
667 greg 2.47 for (i = 0; i < hp->ns; i++)
668     for (j = 0; j < hp->ns; j += !i|(i==hp->ns-1) ? 1 : hp->ns-1) {
669     AMBSAMP *ap = &ambsam(hp,i,j);
670 greg 2.50 if ((ap->d <= FTINY) | (ap->d >= max_d))
671     continue; /* too far or too near */
672 greg 2.47 VSUB(vec, ap->p, hp->rp->rop);
673 greg 2.62 u = DOT(vec, uv[0]);
674     v = DOT(vec, uv[1]);
675     if ((r0*r0*u*u + r1*r1*v*v) * ap->d*ap->d <= u*u + v*v)
676 greg 2.49 continue; /* occluder outside ellipse */
677     ang = atan2a(v, u); /* else set direction flags */
678 greg 2.66 for (a1 = ang-ang_res; a1 <= ang+ang_res; a1 += ang_step)
679 greg 2.50 flgs |= 1L<<(int)(16/PI*(a1 + 2.*PI*(a1 < 0)));
680 greg 2.47 }
681 greg 2.58 /* add low-angle incident (< 20deg) */
682 greg 2.78 if (fabs(hp->rp->rod) <= 0.342 && hp->rp->parent != NULL &&
683     (m = findmaterial(hp->rp->parent->ro)) != NULL &&
684     isopaque(m->otype)) {
685 greg 2.58 u = -DOT(hp->rp->rdir, uv[0]);
686     v = -DOT(hp->rp->rdir, uv[1]);
687     if ((r0*r0*u*u + r1*r1*v*v) > hp->rp->rot*hp->rp->rot) {
688     ang = atan2a(v, u);
689     ang += 2.*PI*(ang < 0);
690     ang *= 16/PI;
691     if ((ang < .5) | (ang >= 31.5))
692     flgs |= 0x80000001;
693     else
694     flgs |= 3L<<(int)(ang-.5);
695     }
696     }
697 greg 2.49 return(flgs);
698 greg 2.47 }
699    
700    
701 greg 2.26 int
702     doambient( /* compute ambient component */
703     COLOR rcol, /* input/output color */
704     RAY *r,
705     double wt,
706 greg 2.27 FVECT uv[2], /* returned (optional) */
707     float ra[2], /* returned (optional) */
708     float pg[2], /* returned (optional) */
709 greg 2.49 float dg[2], /* returned (optional) */
710     uint32 *crlp /* returned (optional) */
711 greg 2.26 )
712     {
713 greg 2.61 AMBHEMI *hp = samp_hemi(rcol, r, wt);
714 greg 2.41 FVECT my_uv[2];
715 greg 2.61 double d, K;
716 greg 2.41 AMBSAMP *ap;
717 greg 2.61 int i;
718     /* clear return values */
719 greg 2.26 if (uv != NULL)
720     memset(uv, 0, sizeof(FVECT)*2);
721     if (ra != NULL)
722     ra[0] = ra[1] = 0.0;
723     if (pg != NULL)
724     pg[0] = pg[1] = 0.0;
725     if (dg != NULL)
726     dg[0] = dg[1] = 0.0;
727 greg 2.49 if (crlp != NULL)
728     *crlp = 0;
729 greg 2.61 if (hp == NULL) /* sampling falure? */
730     return(0);
731    
732     if ((ra == NULL) & (pg == NULL) & (dg == NULL) ||
733 greg 2.68 (hp->sampOK < 0) | (hp->ns < 6)) {
734 greg 2.61 free(hp); /* Hessian not requested/possible */
735     return(-1); /* value-only return value */
736 greg 2.26 }
737 greg 2.61 if ((d = bright(rcol)) > FTINY) { /* normalize Y values */
738 greg 2.45 d = 0.99*(hp->ns*hp->ns)/d;
739 greg 2.38 K = 0.01;
740 greg 2.45 } else { /* or fall back on geometric Hessian */
741 greg 2.38 K = 1.0;
742     pg = NULL;
743     dg = NULL;
744 greg 2.53 crlp = NULL;
745 greg 2.38 }
746 greg 2.29 ap = hp->sa; /* relative Y channel from here on... */
747 greg 2.26 for (i = hp->ns*hp->ns; i--; ap++)
748 greg 2.38 colval(ap->v,CIEY) = bright(ap->v)*d + K;
749 greg 2.26
750     if (uv == NULL) /* make sure we have axis pointers */
751     uv = my_uv;
752     /* compute radii & pos. gradient */
753     ambHessian(hp, uv, ra, pg);
754 greg 2.29
755 greg 2.26 if (dg != NULL) /* compute direction gradient */
756     ambdirgrad(hp, uv, dg);
757 greg 2.29
758 greg 2.28 if (ra != NULL) { /* scale/clamp radii */
759 greg 2.35 if (pg != NULL) {
760     if (ra[0]*(d = fabs(pg[0])) > 1.0)
761     ra[0] = 1.0/d;
762     if (ra[1]*(d = fabs(pg[1])) > 1.0)
763     ra[1] = 1.0/d;
764 greg 2.48 if (ra[0] > ra[1])
765     ra[0] = ra[1];
766 greg 2.35 }
767 greg 2.29 if (ra[0] < minarad) {
768     ra[0] = minarad;
769     if (ra[1] < minarad)
770     ra[1] = minarad;
771     }
772 greg 2.60 ra[0] *= d = 1.0/sqrt(wt);
773 greg 2.26 if ((ra[1] *= d) > 2.0*ra[0])
774     ra[1] = 2.0*ra[0];
775 greg 2.28 if (ra[1] > maxarad) {
776     ra[1] = maxarad;
777     if (ra[0] > maxarad)
778     ra[0] = maxarad;
779     }
780 greg 2.53 /* flag encroached directions */
781 greg 2.71 if (crlp != NULL)
782 greg 2.49 *crlp = ambcorral(hp, uv, ra[0]*ambacc, ra[1]*ambacc);
783 greg 2.35 if (pg != NULL) { /* cap gradient if necessary */
784     d = pg[0]*pg[0]*ra[0]*ra[0] + pg[1]*pg[1]*ra[1]*ra[1];
785     if (d > 1.0) {
786     d = 1.0/sqrt(d);
787     pg[0] *= d;
788     pg[1] *= d;
789     }
790     }
791 greg 2.26 }
792     free(hp); /* clean up and return */
793     return(1);
794     }
795    
796    
797 greg 2.25 #else /* ! NEWAMB */
798 greg 1.1
799    
800 greg 2.15 void
801 greg 2.14 inithemi( /* initialize sampling hemisphere */
802 greg 2.23 AMBHEMI *hp,
803 greg 2.16 COLOR ac,
804 greg 2.14 RAY *r,
805     double wt
806     )
807 greg 1.1 {
808 greg 2.16 double d;
809 greg 2.23 int i;
810 greg 2.14 /* set number of divisions */
811 greg 2.16 if (ambacc <= FTINY &&
812 greg 2.20 wt > (d = 0.8*intens(ac)*r->rweight/(ambdiv*minweight)))
813 greg 2.16 wt = d; /* avoid ray termination */
814     hp->nt = sqrt(ambdiv * wt / PI) + 0.5;
815 greg 2.14 i = ambacc > FTINY ? 3 : 1; /* minimum number of samples */
816     if (hp->nt < i)
817     hp->nt = i;
818     hp->np = PI * hp->nt + 0.5;
819     /* set number of super-samples */
820 greg 2.15 hp->ns = ambssamp * wt + 0.5;
821 greg 2.16 /* assign coefficient */
822 greg 2.14 copycolor(hp->acoef, ac);
823 greg 2.16 d = 1.0/(hp->nt*hp->np);
824     scalecolor(hp->acoef, d);
825 greg 2.14 /* make axes */
826     VCOPY(hp->uz, r->ron);
827     hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
828     for (i = 0; i < 3; i++)
829     if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6)
830     break;
831     if (i >= 3)
832     error(CONSISTENCY, "bad ray direction in inithemi");
833     hp->uy[i] = 1.0;
834     fcross(hp->ux, hp->uy, hp->uz);
835     normalize(hp->ux);
836     fcross(hp->uy, hp->uz, hp->ux);
837 greg 1.1 }
838    
839    
840 greg 2.9 int
841 greg 2.14 divsample( /* sample a division */
842 greg 2.23 AMBSAMP *dp,
843 greg 2.14 AMBHEMI *h,
844     RAY *r
845     )
846 greg 1.1 {
847     RAY ar;
848 greg 1.11 int hlist[3];
849     double spt[2];
850 greg 1.1 double xd, yd, zd;
851     double b2;
852     double phi;
853 greg 2.23 int i;
854 greg 2.15 /* ambient coefficient for weight */
855 greg 2.16 if (ambacc > FTINY)
856     setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
857     else
858     copycolor(ar.rcoef, h->acoef);
859 greg 2.14 if (rayorigin(&ar, AMBIENT, r, ar.rcoef) < 0)
860 greg 1.4 return(-1);
861 greg 2.17 if (ambacc > FTINY) {
862     multcolor(ar.rcoef, h->acoef);
863     scalecolor(ar.rcoef, 1./AVGREFL);
864     }
865 greg 1.1 hlist[0] = r->rno;
866     hlist[1] = dp->t;
867     hlist[2] = dp->p;
868 greg 1.13 multisamp(spt, 2, urand(ilhash(hlist,3)+dp->n));
869 greg 1.11 zd = sqrt((dp->t + spt[0])/h->nt);
870     phi = 2.0*PI * (dp->p + spt[1])/h->np;
871 gwlarson 2.8 xd = tcos(phi) * zd;
872     yd = tsin(phi) * zd;
873 greg 1.1 zd = sqrt(1.0 - zd*zd);
874 greg 1.2 for (i = 0; i < 3; i++)
875     ar.rdir[i] = xd*h->ux[i] +
876     yd*h->uy[i] +
877     zd*h->uz[i];
878 greg 2.22 checknorm(ar.rdir);
879 greg 1.2 dimlist[ndims++] = dp->t*h->np + dp->p + 90171;
880 greg 1.1 rayvalue(&ar);
881     ndims--;
882 greg 2.16 multcolor(ar.rcol, ar.rcoef); /* apply coefficient */
883 greg 1.1 addcolor(dp->v, ar.rcol);
884 greg 2.9 /* use rt to improve gradient calc */
885     if (ar.rt > FTINY && ar.rt < FHUGE)
886     dp->r += 1.0/ar.rt;
887 greg 1.1 /* (re)initialize error */
888     if (dp->n++) {
889     b2 = bright(dp->v)/dp->n - bright(ar.rcol);
890     b2 = b2*b2 + dp->k*((dp->n-1)*(dp->n-1));
891     dp->k = b2/(dp->n*dp->n);
892     } else
893     dp->k = 0.0;
894 greg 1.4 return(0);
895 greg 1.1 }
896    
897    
898 greg 2.14 static int
899     ambcmp( /* decreasing order */
900     const void *p1,
901     const void *p2
902     )
903     {
904     const AMBSAMP *d1 = (const AMBSAMP *)p1;
905     const AMBSAMP *d2 = (const AMBSAMP *)p2;
906    
907     if (d1->k < d2->k)
908     return(1);
909     if (d1->k > d2->k)
910     return(-1);
911     return(0);
912     }
913    
914    
915     static int
916     ambnorm( /* standard order */
917     const void *p1,
918     const void *p2
919     )
920     {
921     const AMBSAMP *d1 = (const AMBSAMP *)p1;
922     const AMBSAMP *d2 = (const AMBSAMP *)p2;
923 greg 2.23 int c;
924 greg 2.14
925     if ( (c = d1->t - d2->t) )
926     return(c);
927     return(d1->p - d2->p);
928     }
929    
930    
931 greg 1.1 double
932 greg 2.14 doambient( /* compute ambient component */
933 greg 2.23 COLOR rcol,
934 greg 2.14 RAY *r,
935     double wt,
936     FVECT pg,
937     FVECT dg
938     )
939 greg 1.1 {
940 greg 2.24 double b, d=0;
941 greg 1.1 AMBHEMI hemi;
942     AMBSAMP *div;
943     AMBSAMP dnew;
944 greg 2.23 double acol[3];
945     AMBSAMP *dp;
946 greg 1.1 double arad;
947 greg 2.19 int divcnt;
948 greg 2.23 int i, j;
949 greg 1.1 /* initialize hemisphere */
950 greg 2.23 inithemi(&hemi, rcol, r, wt);
951 greg 2.19 divcnt = hemi.nt * hemi.np;
952 greg 2.17 /* initialize */
953     if (pg != NULL)
954     pg[0] = pg[1] = pg[2] = 0.0;
955     if (dg != NULL)
956     dg[0] = dg[1] = dg[2] = 0.0;
957 greg 2.23 setcolor(rcol, 0.0, 0.0, 0.0);
958 greg 2.19 if (divcnt == 0)
959 greg 1.1 return(0.0);
960 greg 2.14 /* allocate super-samples */
961 greg 2.15 if (hemi.ns > 0 || pg != NULL || dg != NULL) {
962 greg 2.19 div = (AMBSAMP *)malloc(divcnt*sizeof(AMBSAMP));
963 greg 1.1 if (div == NULL)
964     error(SYSTEM, "out of memory in doambient");
965     } else
966     div = NULL;
967     /* sample the divisions */
968     arad = 0.0;
969 greg 2.23 acol[0] = acol[1] = acol[2] = 0.0;
970 greg 1.1 if ((dp = div) == NULL)
971     dp = &dnew;
972 greg 2.19 divcnt = 0;
973 greg 1.1 for (i = 0; i < hemi.nt; i++)
974     for (j = 0; j < hemi.np; j++) {
975     dp->t = i; dp->p = j;
976     setcolor(dp->v, 0.0, 0.0, 0.0);
977 greg 1.2 dp->r = 0.0;
978 greg 1.1 dp->n = 0;
979 greg 2.16 if (divsample(dp, &hemi, r) < 0) {
980 greg 2.19 if (div != NULL)
981     dp++;
982 greg 2.16 continue;
983     }
984 greg 2.6 arad += dp->r;
985 greg 2.19 divcnt++;
986 greg 1.1 if (div != NULL)
987     dp++;
988 greg 2.6 else
989 greg 1.1 addcolor(acol, dp->v);
990     }
991 greg 2.21 if (!divcnt) {
992     if (div != NULL)
993     free((void *)div);
994 greg 2.19 return(0.0); /* no samples taken */
995 greg 2.21 }
996 greg 2.19 if (divcnt < hemi.nt*hemi.np) {
997     pg = dg = NULL; /* incomplete sampling */
998     hemi.ns = 0;
999     } else if (arad > FTINY && divcnt/arad < minarad) {
1000 greg 2.15 hemi.ns = 0; /* close enough */
1001 greg 2.19 } else if (hemi.ns > 0) { /* else perform super-sampling? */
1002 greg 1.4 comperrs(div, &hemi); /* compute errors */
1003 greg 2.19 qsort(div, divcnt, sizeof(AMBSAMP), ambcmp); /* sort divs */
1004 greg 1.1 /* super-sample */
1005 greg 2.15 for (i = hemi.ns; i > 0; i--) {
1006 schorsch 2.11 dnew = *div;
1007 greg 2.16 if (divsample(&dnew, &hemi, r) < 0) {
1008     dp++;
1009     continue;
1010     }
1011     dp = div; /* reinsert */
1012 greg 2.19 j = divcnt < i ? divcnt : i;
1013 greg 1.1 while (--j > 0 && dnew.k < dp[1].k) {
1014 schorsch 2.11 *dp = *(dp+1);
1015 greg 1.1 dp++;
1016     }
1017 schorsch 2.11 *dp = dnew;
1018 greg 1.1 }
1019 greg 1.2 if (pg != NULL || dg != NULL) /* restore order */
1020 greg 2.19 qsort(div, divcnt, sizeof(AMBSAMP), ambnorm);
1021 greg 1.1 }
1022     /* compute returned values */
1023 greg 1.3 if (div != NULL) {
1024 greg 2.19 arad = 0.0; /* note: divcnt may be < nt*np */
1025     for (i = hemi.nt*hemi.np, dp = div; i-- > 0; dp++) {
1026 greg 1.3 arad += dp->r;
1027     if (dp->n > 1) {
1028     b = 1.0/dp->n;
1029     scalecolor(dp->v, b);
1030     dp->r *= b;
1031     dp->n = 1;
1032     }
1033     addcolor(acol, dp->v);
1034     }
1035 greg 1.5 b = bright(acol);
1036 greg 1.6 if (b > FTINY) {
1037 greg 2.17 b = 1.0/b; /* compute & normalize gradient(s) */
1038 greg 1.6 if (pg != NULL) {
1039     posgradient(pg, div, &hemi);
1040     for (i = 0; i < 3; i++)
1041     pg[i] *= b;
1042     }
1043     if (dg != NULL) {
1044     dirgradient(dg, div, &hemi);
1045     for (i = 0; i < 3; i++)
1046     dg[i] *= b;
1047     }
1048 greg 1.5 }
1049 greg 2.9 free((void *)div);
1050 greg 1.3 }
1051 greg 2.23 copycolor(rcol, acol);
1052 greg 1.1 if (arad <= FTINY)
1053 greg 1.16 arad = maxarad;
1054 greg 2.3 else
1055 greg 2.19 arad = (divcnt+hemi.ns)/arad;
1056 greg 1.15 if (pg != NULL) { /* reduce radius if gradient large */
1057     d = DOT(pg,pg);
1058     if (d*arad*arad > 1.0)
1059     arad = 1.0/sqrt(d);
1060     }
1061 greg 1.16 if (arad < minarad) {
1062 greg 1.1 arad = minarad;
1063 greg 1.16 if (pg != NULL && d*arad*arad > 1.0) { /* cap gradient */
1064     d = 1.0/arad/sqrt(d);
1065     for (i = 0; i < 3; i++)
1066     pg[i] *= d;
1067     }
1068     }
1069 greg 2.3 if ((arad /= sqrt(wt)) > maxarad)
1070     arad = maxarad;
1071     return(arad);
1072 greg 1.1 }
1073    
1074    
1075 greg 2.9 void
1076 greg 2.14 comperrs( /* compute initial error estimates */
1077     AMBSAMP *da, /* assumes standard ordering */
1078 greg 2.23 AMBHEMI *hp
1079 greg 2.14 )
1080 greg 1.1 {
1081     double b, b2;
1082     int i, j;
1083 greg 2.23 AMBSAMP *dp;
1084 greg 1.1 /* sum differences from neighbors */
1085     dp = da;
1086     for (i = 0; i < hp->nt; i++)
1087     for (j = 0; j < hp->np; j++) {
1088 greg 1.6 #ifdef DEBUG
1089     if (dp->t != i || dp->p != j)
1090     error(CONSISTENCY,
1091     "division order in comperrs");
1092     #endif
1093 greg 1.1 b = bright(dp[0].v);
1094     if (i > 0) { /* from above */
1095     b2 = bright(dp[-hp->np].v) - b;
1096     b2 *= b2 * 0.25;
1097     dp[0].k += b2;
1098     dp[-hp->np].k += b2;
1099     }
1100     if (j > 0) { /* from behind */
1101     b2 = bright(dp[-1].v) - b;
1102     b2 *= b2 * 0.25;
1103     dp[0].k += b2;
1104     dp[-1].k += b2;
1105 greg 1.4 } else { /* around */
1106     b2 = bright(dp[hp->np-1].v) - b;
1107 greg 1.1 b2 *= b2 * 0.25;
1108     dp[0].k += b2;
1109 greg 1.4 dp[hp->np-1].k += b2;
1110 greg 1.1 }
1111     dp++;
1112     }
1113     /* divide by number of neighbors */
1114     dp = da;
1115     for (j = 0; j < hp->np; j++) /* top row */
1116     (dp++)->k *= 1.0/3.0;
1117     if (hp->nt < 2)
1118     return;
1119     for (i = 1; i < hp->nt-1; i++) /* central region */
1120     for (j = 0; j < hp->np; j++)
1121     (dp++)->k *= 0.25;
1122     for (j = 0; j < hp->np; j++) /* bottom row */
1123     (dp++)->k *= 1.0/3.0;
1124     }
1125    
1126    
1127 greg 2.9 void
1128 greg 2.14 posgradient( /* compute position gradient */
1129     FVECT gv,
1130     AMBSAMP *da, /* assumes standard ordering */
1131 greg 2.23 AMBHEMI *hp
1132 greg 2.14 )
1133 greg 1.1 {
1134 greg 2.23 int i, j;
1135 greg 2.2 double nextsine, lastsine, b, d;
1136 greg 1.2 double mag0, mag1;
1137     double phi, cosp, sinp, xd, yd;
1138 greg 2.23 AMBSAMP *dp;
1139 greg 1.2
1140     xd = yd = 0.0;
1141     for (j = 0; j < hp->np; j++) {
1142     dp = da + j;
1143     mag0 = mag1 = 0.0;
1144 greg 2.2 lastsine = 0.0;
1145 greg 1.2 for (i = 0; i < hp->nt; i++) {
1146     #ifdef DEBUG
1147     if (dp->t != i || dp->p != j)
1148     error(CONSISTENCY,
1149     "division order in posgradient");
1150     #endif
1151     b = bright(dp->v);
1152     if (i > 0) {
1153     d = dp[-hp->np].r;
1154     if (dp[0].r > d) d = dp[0].r;
1155 greg 2.2 /* sin(t)*cos(t)^2 */
1156     d *= lastsine * (1.0 - (double)i/hp->nt);
1157 greg 1.2 mag0 += d*(b - bright(dp[-hp->np].v));
1158     }
1159 greg 2.2 nextsine = sqrt((double)(i+1)/hp->nt);
1160 greg 1.2 if (j > 0) {
1161     d = dp[-1].r;
1162     if (dp[0].r > d) d = dp[0].r;
1163 greg 2.2 mag1 += d * (nextsine - lastsine) *
1164     (b - bright(dp[-1].v));
1165 greg 1.2 } else {
1166     d = dp[hp->np-1].r;
1167     if (dp[0].r > d) d = dp[0].r;
1168 greg 2.2 mag1 += d * (nextsine - lastsine) *
1169     (b - bright(dp[hp->np-1].v));
1170 greg 1.2 }
1171     dp += hp->np;
1172 greg 2.2 lastsine = nextsine;
1173 greg 1.2 }
1174 greg 2.2 mag0 *= 2.0*PI / hp->np;
1175 greg 1.2 phi = 2.0*PI * (double)j/hp->np;
1176 gwlarson 2.8 cosp = tcos(phi); sinp = tsin(phi);
1177 greg 1.2 xd += mag0*cosp - mag1*sinp;
1178     yd += mag0*sinp + mag1*cosp;
1179     }
1180     for (i = 0; i < 3; i++)
1181 greg 2.16 gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])*(hp->nt*hp->np)/PI;
1182 greg 1.1 }
1183    
1184    
1185 greg 2.9 void
1186 greg 2.14 dirgradient( /* compute direction gradient */
1187     FVECT gv,
1188     AMBSAMP *da, /* assumes standard ordering */
1189 greg 2.23 AMBHEMI *hp
1190 greg 2.14 )
1191 greg 1.1 {
1192 greg 2.23 int i, j;
1193 greg 1.2 double mag;
1194     double phi, xd, yd;
1195 greg 2.23 AMBSAMP *dp;
1196 greg 1.2
1197     xd = yd = 0.0;
1198     for (j = 0; j < hp->np; j++) {
1199     dp = da + j;
1200     mag = 0.0;
1201     for (i = 0; i < hp->nt; i++) {
1202     #ifdef DEBUG
1203     if (dp->t != i || dp->p != j)
1204     error(CONSISTENCY,
1205     "division order in dirgradient");
1206     #endif
1207 greg 2.2 /* tan(t) */
1208     mag += bright(dp->v)/sqrt(hp->nt/(i+.5) - 1.0);
1209 greg 1.2 dp += hp->np;
1210     }
1211     phi = 2.0*PI * (j+.5)/hp->np + PI/2.0;
1212 gwlarson 2.8 xd += mag * tcos(phi);
1213     yd += mag * tsin(phi);
1214 greg 1.2 }
1215     for (i = 0; i < 3; i++)
1216 greg 2.16 gv[i] = xd*hp->ux[i] + yd*hp->uy[i];
1217 greg 1.1 }
1218 greg 2.25
1219     #endif /* ! NEWAMB */