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root/radiance/ray/src/rt/ambcomp.c
Revision: 2.76
Committed: Thu Jan 26 16:46:58 2017 UTC (7 years, 3 months ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 2.75: +3 -3 lines
Log Message:
Fixed bug in scenes with zero octree size

File Contents

# User Rev Content
1 greg 1.1 #ifndef lint
2 greg 2.76 static const char RCSid[] = "$Id: ambcomp.c,v 2.75 2016/10/15 14:54:39 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 2.55 float *earr = (float *)calloc(hp->ns*hp->ns, sizeof(float));
164 greg 2.41 float *ep;
165 greg 2.42 AMBSAMP *ap;
166 greg 2.41 double b, d2;
167     int i, j;
168    
169     if (earr == NULL) /* out of memory? */
170     return(NULL);
171     /* compute squared neighbor diffs */
172 greg 2.42 for (ap = hp->sa, ep = earr, i = 0; i < hp->ns; i++)
173     for (j = 0; j < hp->ns; j++, ap++, ep++) {
174     b = bright(ap[0].v);
175 greg 2.41 if (i) { /* from above */
176 greg 2.42 d2 = b - bright(ap[-hp->ns].v);
177 greg 2.41 d2 *= d2;
178     ep[0] += d2;
179     ep[-hp->ns] += d2;
180     }
181 greg 2.55 if (!j) continue;
182     /* from behind */
183     d2 = b - bright(ap[-1].v);
184     d2 *= d2;
185     ep[0] += d2;
186     ep[-1] += d2;
187     if (!i) continue;
188     /* diagonal */
189     d2 = b - bright(ap[-hp->ns-1].v);
190     d2 *= d2;
191     ep[0] += d2;
192     ep[-hp->ns-1] += d2;
193 greg 2.41 }
194     /* correct for number of neighbors */
195 greg 2.55 earr[0] *= 8./3.;
196     earr[hp->ns-1] *= 8./3.;
197     earr[(hp->ns-1)*hp->ns] *= 8./3.;
198     earr[(hp->ns-1)*hp->ns + hp->ns-1] *= 8./3.;
199 greg 2.41 for (i = 1; i < hp->ns-1; i++) {
200 greg 2.55 earr[i*hp->ns] *= 8./5.;
201     earr[i*hp->ns + hp->ns-1] *= 8./5.;
202 greg 2.41 }
203     for (j = 1; j < hp->ns-1; j++) {
204 greg 2.55 earr[j] *= 8./5.;
205     earr[(hp->ns-1)*hp->ns + j] *= 8./5.;
206 greg 2.41 }
207     return(earr);
208     }
209    
210    
211 greg 2.43 /* Perform super-sampling on hemisphere (introduces bias) */
212 greg 2.41 static void
213 greg 2.61 ambsupersamp(AMBHEMI *hp, int cnt)
214 greg 2.41 {
215     float *earr = getambdiffs(hp);
216 greg 2.54 double e2rem = 0;
217 greg 2.41 AMBSAMP *ap;
218     float *ep;
219 greg 2.55 int i, j, n, nss;
220 greg 2.41
221     if (earr == NULL) /* just skip calc. if no memory */
222     return;
223 greg 2.54 /* accumulate estimated variances */
224 greg 2.55 for (ep = earr + hp->ns*hp->ns; ep > earr; )
225     e2rem += *--ep;
226 greg 2.41 ep = earr; /* perform super-sampling */
227     for (ap = hp->sa, i = 0; i < hp->ns; i++)
228     for (j = 0; j < hp->ns; j++, ap++) {
229 greg 2.55 if (e2rem <= FTINY)
230     goto done; /* nothing left to do */
231     nss = *ep/e2rem*cnt + frandom();
232 greg 2.62 for (n = 1; n <= nss && ambsample(hp,i,j,n); n++)
233     --cnt;
234 greg 2.61 e2rem -= *ep++; /* update remainder */
235 greg 2.41 }
236 greg 2.55 done:
237 greg 2.41 free(earr);
238     }
239    
240    
241 greg 2.61 static AMBHEMI *
242     samp_hemi( /* sample indirect hemisphere */
243     COLOR rcol,
244     RAY *r,
245     double wt
246     )
247     {
248     AMBHEMI *hp;
249     double d;
250     int n, i, j;
251     /* set number of divisions */
252     if (ambacc <= FTINY &&
253     wt > (d = 0.8*intens(rcol)*r->rweight/(ambdiv*minweight)))
254     wt = d; /* avoid ray termination */
255     n = sqrt(ambdiv * wt) + 0.5;
256 greg 2.68 i = 1 + 5*(ambacc > FTINY); /* minimum number of samples */
257 greg 2.61 if (n < i)
258     n = i;
259     /* allocate sampling array */
260     hp = (AMBHEMI *)malloc(sizeof(AMBHEMI) + sizeof(AMBSAMP)*(n*n - 1));
261     if (hp == NULL)
262     error(SYSTEM, "out of memory in samp_hemi");
263     hp->rp = r;
264     hp->ns = n;
265     hp->acol[RED] = hp->acol[GRN] = hp->acol[BLU] = 0.0;
266 greg 2.62 memset(hp->sa, 0, sizeof(AMBSAMP)*n*n);
267 greg 2.61 hp->sampOK = 0;
268     /* assign coefficient */
269     copycolor(hp->acoef, rcol);
270     d = 1.0/(n*n);
271     scalecolor(hp->acoef, d);
272     /* make tangent plane axes */
273 greg 2.70 if (!getperpendicular(hp->ux, r->ron, 1))
274 greg 2.61 error(CONSISTENCY, "bad ray direction in samp_hemi");
275     VCROSS(hp->uy, r->ron, hp->ux);
276     /* sample divisions */
277     for (i = hp->ns; i--; )
278     for (j = hp->ns; j--; )
279     hp->sampOK += ambsample(hp, i, j, 0);
280     copycolor(rcol, hp->acol);
281     if (!hp->sampOK) { /* utter failure? */
282     free(hp);
283     return(NULL);
284     }
285     if (hp->sampOK < hp->ns*hp->ns) {
286     hp->sampOK *= -1; /* soft failure */
287     return(hp);
288     }
289     n = ambssamp*wt + 0.5;
290     if (n > 8) { /* perform super-sampling? */
291     ambsupersamp(hp, n);
292     copycolor(rcol, hp->acol);
293     }
294     return(hp); /* all is well */
295     }
296    
297    
298 greg 2.46 /* Return brightness of farthest ambient sample */
299     static double
300 greg 2.56 back_ambval(AMBHEMI *hp, const int n1, const int n2, const int n3)
301 greg 2.46 {
302 greg 2.56 if (hp->sa[n1].d <= hp->sa[n2].d) {
303     if (hp->sa[n1].d <= hp->sa[n3].d)
304     return(colval(hp->sa[n1].v,CIEY));
305     return(colval(hp->sa[n3].v,CIEY));
306     }
307     if (hp->sa[n2].d <= hp->sa[n3].d)
308     return(colval(hp->sa[n2].v,CIEY));
309     return(colval(hp->sa[n3].v,CIEY));
310 greg 2.46 }
311    
312    
313 greg 2.27 /* Compute vectors and coefficients for Hessian/gradient calcs */
314     static void
315 greg 2.56 comp_fftri(FFTRI *ftp, AMBHEMI *hp, const int n0, const int n1)
316 greg 2.27 {
317 greg 2.56 double rdot_cp, dot_e, dot_er, rdot_r, rdot_r1, J2;
318     int ii;
319    
320     VSUB(ftp->r_i, hp->sa[n0].p, hp->rp->rop);
321     VSUB(ftp->r_i1, hp->sa[n1].p, hp->rp->rop);
322     VSUB(ftp->e_i, hp->sa[n1].p, hp->sa[n0].p);
323 greg 2.35 VCROSS(ftp->rcp, ftp->r_i, ftp->r_i1);
324     rdot_cp = 1.0/DOT(ftp->rcp,ftp->rcp);
325 greg 2.27 dot_e = DOT(ftp->e_i,ftp->e_i);
326     dot_er = DOT(ftp->e_i, ftp->r_i);
327 greg 2.32 rdot_r = 1.0/DOT(ftp->r_i,ftp->r_i);
328     rdot_r1 = 1.0/DOT(ftp->r_i1,ftp->r_i1);
329     ftp->I1 = acos( DOT(ftp->r_i, ftp->r_i1) * sqrt(rdot_r*rdot_r1) ) *
330 greg 2.35 sqrt( rdot_cp );
331 greg 2.32 ftp->I2 = ( DOT(ftp->e_i, ftp->r_i1)*rdot_r1 - dot_er*rdot_r +
332 greg 2.35 dot_e*ftp->I1 )*0.5*rdot_cp;
333 greg 2.32 J2 = ( 0.5*(rdot_r - rdot_r1) - dot_er*ftp->I2 ) / dot_e;
334 greg 2.46 for (ii = 3; ii--; )
335     ftp->rI2_eJ2[ii] = ftp->I2*ftp->r_i[ii] + J2*ftp->e_i[ii];
336 greg 2.27 }
337    
338    
339 greg 2.28 /* Compose 3x3 matrix from two vectors */
340 greg 2.27 static void
341     compose_matrix(FVECT mat[3], FVECT va, FVECT vb)
342     {
343     mat[0][0] = 2.0*va[0]*vb[0];
344     mat[1][1] = 2.0*va[1]*vb[1];
345     mat[2][2] = 2.0*va[2]*vb[2];
346     mat[0][1] = mat[1][0] = va[0]*vb[1] + va[1]*vb[0];
347     mat[0][2] = mat[2][0] = va[0]*vb[2] + va[2]*vb[0];
348     mat[1][2] = mat[2][1] = va[1]*vb[2] + va[2]*vb[1];
349     }
350    
351    
352     /* Compute partial 3x3 Hessian matrix for edge */
353     static void
354     comp_hessian(FVECT hess[3], FFTRI *ftp, FVECT nrm)
355     {
356 greg 2.35 FVECT ncp;
357 greg 2.27 FVECT m1[3], m2[3], m3[3], m4[3];
358     double d1, d2, d3, d4;
359     double I3, J3, K3;
360     int i, j;
361     /* compute intermediate coefficients */
362     d1 = 1.0/DOT(ftp->r_i,ftp->r_i);
363     d2 = 1.0/DOT(ftp->r_i1,ftp->r_i1);
364     d3 = 1.0/DOT(ftp->e_i,ftp->e_i);
365     d4 = DOT(ftp->e_i, ftp->r_i);
366 greg 2.35 I3 = ( DOT(ftp->e_i, ftp->r_i1)*d2*d2 - d4*d1*d1 + 3.0/d3*ftp->I2 )
367     / ( 4.0*DOT(ftp->rcp,ftp->rcp) );
368 greg 2.27 J3 = 0.25*d3*(d1*d1 - d2*d2) - d4*d3*I3;
369     K3 = d3*(ftp->I2 - I3/d1 - 2.0*d4*J3);
370     /* intermediate matrices */
371 greg 2.35 VCROSS(ncp, nrm, ftp->e_i);
372     compose_matrix(m1, ncp, ftp->rI2_eJ2);
373 greg 2.27 compose_matrix(m2, ftp->r_i, ftp->r_i);
374     compose_matrix(m3, ftp->e_i, ftp->e_i);
375     compose_matrix(m4, ftp->r_i, ftp->e_i);
376 greg 2.35 d1 = DOT(nrm, ftp->rcp);
377 greg 2.27 d2 = -d1*ftp->I2;
378     d1 *= 2.0;
379     for (i = 3; i--; ) /* final matrix sum */
380     for (j = 3; j--; ) {
381     hess[i][j] = m1[i][j] + d1*( I3*m2[i][j] + K3*m3[i][j] +
382     2.0*J3*m4[i][j] );
383     hess[i][j] += d2*(i==j);
384 greg 2.46 hess[i][j] *= -1.0/PI;
385 greg 2.27 }
386     }
387    
388    
389     /* Reverse hessian calculation result for edge in other direction */
390     static void
391     rev_hessian(FVECT hess[3])
392     {
393     int i;
394    
395     for (i = 3; i--; ) {
396     hess[i][0] = -hess[i][0];
397     hess[i][1] = -hess[i][1];
398     hess[i][2] = -hess[i][2];
399     }
400     }
401    
402    
403     /* Add to radiometric Hessian from the given triangle */
404     static void
405     add2hessian(FVECT hess[3], FVECT ehess1[3],
406 greg 2.46 FVECT ehess2[3], FVECT ehess3[3], double v)
407 greg 2.27 {
408     int i, j;
409    
410     for (i = 3; i--; )
411     for (j = 3; j--; )
412     hess[i][j] += v*( ehess1[i][j] + ehess2[i][j] + ehess3[i][j] );
413     }
414    
415    
416     /* Compute partial displacement form factor gradient for edge */
417     static void
418     comp_gradient(FVECT grad, FFTRI *ftp, FVECT nrm)
419     {
420 greg 2.35 FVECT ncp;
421 greg 2.27 double f1;
422     int i;
423    
424 greg 2.35 f1 = 2.0*DOT(nrm, ftp->rcp);
425     VCROSS(ncp, nrm, ftp->e_i);
426 greg 2.27 for (i = 3; i--; )
427 greg 2.46 grad[i] = (0.5/PI)*( ftp->I1*ncp[i] + f1*ftp->rI2_eJ2[i] );
428 greg 2.27 }
429    
430    
431     /* Reverse gradient calculation result for edge in other direction */
432     static void
433     rev_gradient(FVECT grad)
434     {
435     grad[0] = -grad[0];
436     grad[1] = -grad[1];
437     grad[2] = -grad[2];
438     }
439    
440    
441     /* Add to displacement gradient from the given triangle */
442     static void
443 greg 2.46 add2gradient(FVECT grad, FVECT egrad1, FVECT egrad2, FVECT egrad3, double v)
444 greg 2.27 {
445     int i;
446    
447     for (i = 3; i--; )
448     grad[i] += v*( egrad1[i] + egrad2[i] + egrad3[i] );
449     }
450    
451    
452     /* Compute anisotropic radii and eigenvector directions */
453 greg 2.53 static void
454 greg 2.27 eigenvectors(FVECT uv[2], float ra[2], FVECT hessian[3])
455     {
456     double hess2[2][2];
457     FVECT a, b;
458     double evalue[2], slope1, xmag1;
459     int i;
460     /* project Hessian to sample plane */
461     for (i = 3; i--; ) {
462     a[i] = DOT(hessian[i], uv[0]);
463     b[i] = DOT(hessian[i], uv[1]);
464     }
465     hess2[0][0] = DOT(uv[0], a);
466     hess2[0][1] = DOT(uv[0], b);
467     hess2[1][0] = DOT(uv[1], a);
468     hess2[1][1] = DOT(uv[1], b);
469 greg 2.38 /* compute eigenvalue(s) */
470     i = quadratic(evalue, 1.0, -hess2[0][0]-hess2[1][1],
471     hess2[0][0]*hess2[1][1]-hess2[0][1]*hess2[1][0]);
472     if (i == 1) /* double-root (circle) */
473     evalue[1] = evalue[0];
474     if (!i || ((evalue[0] = fabs(evalue[0])) <= FTINY*FTINY) |
475 greg 2.53 ((evalue[1] = fabs(evalue[1])) <= FTINY*FTINY) ) {
476     ra[0] = ra[1] = maxarad;
477     return;
478     }
479 greg 2.27 if (evalue[0] > evalue[1]) {
480 greg 2.29 ra[0] = sqrt(sqrt(4.0/evalue[0]));
481     ra[1] = sqrt(sqrt(4.0/evalue[1]));
482 greg 2.27 slope1 = evalue[1];
483     } else {
484 greg 2.29 ra[0] = sqrt(sqrt(4.0/evalue[1]));
485     ra[1] = sqrt(sqrt(4.0/evalue[0]));
486 greg 2.27 slope1 = evalue[0];
487     }
488     /* compute unit eigenvectors */
489     if (fabs(hess2[0][1]) <= FTINY)
490     return; /* uv OK as is */
491     slope1 = (slope1 - hess2[0][0]) / hess2[0][1];
492     xmag1 = sqrt(1.0/(1.0 + slope1*slope1));
493     for (i = 3; i--; ) {
494     b[i] = xmag1*uv[0][i] + slope1*xmag1*uv[1][i];
495     a[i] = slope1*xmag1*uv[0][i] - xmag1*uv[1][i];
496     }
497     VCOPY(uv[0], a);
498     VCOPY(uv[1], b);
499     }
500    
501    
502 greg 2.26 static void
503     ambHessian( /* anisotropic radii & pos. gradient */
504     AMBHEMI *hp,
505     FVECT uv[2], /* returned */
506 greg 2.28 float ra[2], /* returned (optional) */
507     float pg[2] /* returned (optional) */
508 greg 2.26 )
509     {
510 greg 2.27 static char memerrmsg[] = "out of memory in ambHessian()";
511     FVECT (*hessrow)[3] = NULL;
512     FVECT *gradrow = NULL;
513     FVECT hessian[3];
514     FVECT gradient;
515     FFTRI fftr;
516     int i, j;
517     /* be sure to assign unit vectors */
518     VCOPY(uv[0], hp->ux);
519     VCOPY(uv[1], hp->uy);
520     /* clock-wise vertex traversal from sample POV */
521     if (ra != NULL) { /* initialize Hessian row buffer */
522 greg 2.28 hessrow = (FVECT (*)[3])malloc(sizeof(FVECT)*3*(hp->ns-1));
523 greg 2.27 if (hessrow == NULL)
524     error(SYSTEM, memerrmsg);
525     memset(hessian, 0, sizeof(hessian));
526     } else if (pg == NULL) /* bogus call? */
527     return;
528     if (pg != NULL) { /* initialize form factor row buffer */
529 greg 2.28 gradrow = (FVECT *)malloc(sizeof(FVECT)*(hp->ns-1));
530 greg 2.27 if (gradrow == NULL)
531     error(SYSTEM, memerrmsg);
532     memset(gradient, 0, sizeof(gradient));
533     }
534     /* compute first row of edges */
535     for (j = 0; j < hp->ns-1; j++) {
536 greg 2.56 comp_fftri(&fftr, hp, AI(hp,0,j), AI(hp,0,j+1));
537 greg 2.27 if (hessrow != NULL)
538     comp_hessian(hessrow[j], &fftr, hp->rp->ron);
539     if (gradrow != NULL)
540     comp_gradient(gradrow[j], &fftr, hp->rp->ron);
541     }
542     /* sum each row of triangles */
543     for (i = 0; i < hp->ns-1; i++) {
544     FVECT hesscol[3]; /* compute first vertical edge */
545     FVECT gradcol;
546 greg 2.56 comp_fftri(&fftr, hp, AI(hp,i,0), AI(hp,i+1,0));
547 greg 2.27 if (hessrow != NULL)
548     comp_hessian(hesscol, &fftr, hp->rp->ron);
549     if (gradrow != NULL)
550     comp_gradient(gradcol, &fftr, hp->rp->ron);
551     for (j = 0; j < hp->ns-1; j++) {
552     FVECT hessdia[3]; /* compute triangle contributions */
553     FVECT graddia;
554 greg 2.46 double backg;
555 greg 2.56 backg = back_ambval(hp, AI(hp,i,j),
556     AI(hp,i,j+1), AI(hp,i+1,j));
557 greg 2.27 /* diagonal (inner) edge */
558 greg 2.56 comp_fftri(&fftr, hp, AI(hp,i,j+1), AI(hp,i+1,j));
559 greg 2.27 if (hessrow != NULL) {
560     comp_hessian(hessdia, &fftr, hp->rp->ron);
561     rev_hessian(hesscol);
562     add2hessian(hessian, hessrow[j], hessdia, hesscol, backg);
563     }
564 greg 2.39 if (gradrow != NULL) {
565 greg 2.27 comp_gradient(graddia, &fftr, hp->rp->ron);
566     rev_gradient(gradcol);
567     add2gradient(gradient, gradrow[j], graddia, gradcol, backg);
568     }
569     /* initialize edge in next row */
570 greg 2.56 comp_fftri(&fftr, hp, AI(hp,i+1,j+1), AI(hp,i+1,j));
571 greg 2.27 if (hessrow != NULL)
572     comp_hessian(hessrow[j], &fftr, hp->rp->ron);
573     if (gradrow != NULL)
574     comp_gradient(gradrow[j], &fftr, hp->rp->ron);
575     /* new column edge & paired triangle */
576 greg 2.56 backg = back_ambval(hp, AI(hp,i+1,j+1),
577     AI(hp,i+1,j), AI(hp,i,j+1));
578     comp_fftri(&fftr, hp, AI(hp,i,j+1), AI(hp,i+1,j+1));
579 greg 2.27 if (hessrow != NULL) {
580     comp_hessian(hesscol, &fftr, hp->rp->ron);
581     rev_hessian(hessdia);
582     add2hessian(hessian, hessrow[j], hessdia, hesscol, backg);
583     if (i < hp->ns-2)
584     rev_hessian(hessrow[j]);
585     }
586     if (gradrow != NULL) {
587     comp_gradient(gradcol, &fftr, hp->rp->ron);
588     rev_gradient(graddia);
589     add2gradient(gradient, gradrow[j], graddia, gradcol, backg);
590     if (i < hp->ns-2)
591     rev_gradient(gradrow[j]);
592     }
593     }
594     }
595     /* release row buffers */
596     if (hessrow != NULL) free(hessrow);
597     if (gradrow != NULL) free(gradrow);
598    
599     if (ra != NULL) /* extract eigenvectors & radii */
600     eigenvectors(uv, ra, hessian);
601 greg 2.32 if (pg != NULL) { /* tangential position gradient */
602     pg[0] = DOT(gradient, uv[0]);
603     pg[1] = DOT(gradient, uv[1]);
604 greg 2.27 }
605     }
606    
607    
608     /* Compute direction gradient from a hemispherical sampling */
609     static void
610     ambdirgrad(AMBHEMI *hp, FVECT uv[2], float dg[2])
611     {
612 greg 2.41 AMBSAMP *ap;
613     double dgsum[2];
614     int n;
615     FVECT vd;
616     double gfact;
617 greg 2.27
618 greg 2.29 dgsum[0] = dgsum[1] = 0.0; /* sum values times -tan(theta) */
619 greg 2.27 for (ap = hp->sa, n = hp->ns*hp->ns; n--; ap++) {
620     /* use vector for azimuth + 90deg */
621     VSUB(vd, ap->p, hp->rp->rop);
622 greg 2.29 /* brightness over cosine factor */
623     gfact = colval(ap->v,CIEY) / DOT(hp->rp->ron, vd);
624 greg 2.40 /* sine = proj_radius/vd_length */
625     dgsum[0] -= DOT(uv[1], vd) * gfact;
626     dgsum[1] += DOT(uv[0], vd) * gfact;
627 greg 2.26 }
628 greg 2.29 dg[0] = dgsum[0] / (hp->ns*hp->ns);
629     dg[1] = dgsum[1] / (hp->ns*hp->ns);
630 greg 2.26 }
631    
632 greg 2.27
633 greg 2.49 /* Compute potential light leak direction flags for cache value */
634     static uint32
635     ambcorral(AMBHEMI *hp, FVECT uv[2], const double r0, const double r1)
636 greg 2.47 {
637 greg 2.50 const double max_d = 1.0/(minarad*ambacc + 0.001);
638 greg 2.66 const double ang_res = 0.5*PI/hp->ns;
639     const double ang_step = ang_res/((int)(16/PI*ang_res) + 1.01);
640 greg 2.51 double avg_d = 0;
641 greg 2.50 uint32 flgs = 0;
642 greg 2.58 FVECT vec;
643 greg 2.62 double u, v;
644 greg 2.58 double ang, a1;
645 greg 2.50 int i, j;
646 greg 2.52 /* don't bother for a few samples */
647 greg 2.72 if (hp->ns < 8)
648 greg 2.52 return(0);
649     /* check distances overhead */
650 greg 2.51 for (i = hp->ns*3/4; i-- > hp->ns>>2; )
651     for (j = hp->ns*3/4; j-- > hp->ns>>2; )
652     avg_d += ambsam(hp,i,j).d;
653     avg_d *= 4.0/(hp->ns*hp->ns);
654 greg 2.52 if (avg_d*r0 >= 1.0) /* ceiling too low for corral? */
655     return(0);
656     if (avg_d >= max_d) /* insurance */
657 greg 2.51 return(0);
658     /* else circle around perimeter */
659 greg 2.47 for (i = 0; i < hp->ns; i++)
660     for (j = 0; j < hp->ns; j += !i|(i==hp->ns-1) ? 1 : hp->ns-1) {
661     AMBSAMP *ap = &ambsam(hp,i,j);
662 greg 2.50 if ((ap->d <= FTINY) | (ap->d >= max_d))
663     continue; /* too far or too near */
664 greg 2.47 VSUB(vec, ap->p, hp->rp->rop);
665 greg 2.62 u = DOT(vec, uv[0]);
666     v = DOT(vec, uv[1]);
667     if ((r0*r0*u*u + r1*r1*v*v) * ap->d*ap->d <= u*u + v*v)
668 greg 2.49 continue; /* occluder outside ellipse */
669     ang = atan2a(v, u); /* else set direction flags */
670 greg 2.66 for (a1 = ang-ang_res; a1 <= ang+ang_res; a1 += ang_step)
671 greg 2.50 flgs |= 1L<<(int)(16/PI*(a1 + 2.*PI*(a1 < 0)));
672 greg 2.47 }
673 greg 2.58 /* add low-angle incident (< 20deg) */
674     if (fabs(hp->rp->rod) <= 0.342) {
675     u = -DOT(hp->rp->rdir, uv[0]);
676     v = -DOT(hp->rp->rdir, uv[1]);
677     if ((r0*r0*u*u + r1*r1*v*v) > hp->rp->rot*hp->rp->rot) {
678     ang = atan2a(v, u);
679     ang += 2.*PI*(ang < 0);
680     ang *= 16/PI;
681     if ((ang < .5) | (ang >= 31.5))
682     flgs |= 0x80000001;
683     else
684     flgs |= 3L<<(int)(ang-.5);
685     }
686     }
687 greg 2.49 return(flgs);
688 greg 2.47 }
689    
690    
691 greg 2.26 int
692     doambient( /* compute ambient component */
693     COLOR rcol, /* input/output color */
694     RAY *r,
695     double wt,
696 greg 2.27 FVECT uv[2], /* returned (optional) */
697     float ra[2], /* returned (optional) */
698     float pg[2], /* returned (optional) */
699 greg 2.49 float dg[2], /* returned (optional) */
700     uint32 *crlp /* returned (optional) */
701 greg 2.26 )
702     {
703 greg 2.61 AMBHEMI *hp = samp_hemi(rcol, r, wt);
704 greg 2.41 FVECT my_uv[2];
705 greg 2.61 double d, K;
706 greg 2.41 AMBSAMP *ap;
707 greg 2.61 int i;
708     /* clear return values */
709 greg 2.26 if (uv != NULL)
710     memset(uv, 0, sizeof(FVECT)*2);
711     if (ra != NULL)
712     ra[0] = ra[1] = 0.0;
713     if (pg != NULL)
714     pg[0] = pg[1] = 0.0;
715     if (dg != NULL)
716     dg[0] = dg[1] = 0.0;
717 greg 2.49 if (crlp != NULL)
718     *crlp = 0;
719 greg 2.61 if (hp == NULL) /* sampling falure? */
720     return(0);
721    
722     if ((ra == NULL) & (pg == NULL) & (dg == NULL) ||
723 greg 2.68 (hp->sampOK < 0) | (hp->ns < 6)) {
724 greg 2.61 free(hp); /* Hessian not requested/possible */
725     return(-1); /* value-only return value */
726 greg 2.26 }
727 greg 2.61 if ((d = bright(rcol)) > FTINY) { /* normalize Y values */
728 greg 2.45 d = 0.99*(hp->ns*hp->ns)/d;
729 greg 2.38 K = 0.01;
730 greg 2.45 } else { /* or fall back on geometric Hessian */
731 greg 2.38 K = 1.0;
732     pg = NULL;
733     dg = NULL;
734 greg 2.53 crlp = NULL;
735 greg 2.38 }
736 greg 2.29 ap = hp->sa; /* relative Y channel from here on... */
737 greg 2.26 for (i = hp->ns*hp->ns; i--; ap++)
738 greg 2.38 colval(ap->v,CIEY) = bright(ap->v)*d + K;
739 greg 2.26
740     if (uv == NULL) /* make sure we have axis pointers */
741     uv = my_uv;
742     /* compute radii & pos. gradient */
743     ambHessian(hp, uv, ra, pg);
744 greg 2.29
745 greg 2.26 if (dg != NULL) /* compute direction gradient */
746     ambdirgrad(hp, uv, dg);
747 greg 2.29
748 greg 2.28 if (ra != NULL) { /* scale/clamp radii */
749 greg 2.35 if (pg != NULL) {
750     if (ra[0]*(d = fabs(pg[0])) > 1.0)
751     ra[0] = 1.0/d;
752     if (ra[1]*(d = fabs(pg[1])) > 1.0)
753     ra[1] = 1.0/d;
754 greg 2.48 if (ra[0] > ra[1])
755     ra[0] = ra[1];
756 greg 2.35 }
757 greg 2.29 if (ra[0] < minarad) {
758     ra[0] = minarad;
759     if (ra[1] < minarad)
760     ra[1] = minarad;
761     }
762 greg 2.60 ra[0] *= d = 1.0/sqrt(wt);
763 greg 2.26 if ((ra[1] *= d) > 2.0*ra[0])
764     ra[1] = 2.0*ra[0];
765 greg 2.28 if (ra[1] > maxarad) {
766     ra[1] = maxarad;
767     if (ra[0] > maxarad)
768     ra[0] = maxarad;
769     }
770 greg 2.53 /* flag encroached directions */
771 greg 2.71 if (crlp != NULL)
772 greg 2.49 *crlp = ambcorral(hp, uv, ra[0]*ambacc, ra[1]*ambacc);
773 greg 2.35 if (pg != NULL) { /* cap gradient if necessary */
774     d = pg[0]*pg[0]*ra[0]*ra[0] + pg[1]*pg[1]*ra[1]*ra[1];
775     if (d > 1.0) {
776     d = 1.0/sqrt(d);
777     pg[0] *= d;
778     pg[1] *= d;
779     }
780     }
781 greg 2.26 }
782     free(hp); /* clean up and return */
783     return(1);
784     }
785    
786    
787 greg 2.25 #else /* ! NEWAMB */
788 greg 1.1
789    
790 greg 2.15 void
791 greg 2.14 inithemi( /* initialize sampling hemisphere */
792 greg 2.23 AMBHEMI *hp,
793 greg 2.16 COLOR ac,
794 greg 2.14 RAY *r,
795     double wt
796     )
797 greg 1.1 {
798 greg 2.16 double d;
799 greg 2.23 int i;
800 greg 2.14 /* set number of divisions */
801 greg 2.16 if (ambacc <= FTINY &&
802 greg 2.20 wt > (d = 0.8*intens(ac)*r->rweight/(ambdiv*minweight)))
803 greg 2.16 wt = d; /* avoid ray termination */
804     hp->nt = sqrt(ambdiv * wt / PI) + 0.5;
805 greg 2.14 i = ambacc > FTINY ? 3 : 1; /* minimum number of samples */
806     if (hp->nt < i)
807     hp->nt = i;
808     hp->np = PI * hp->nt + 0.5;
809     /* set number of super-samples */
810 greg 2.15 hp->ns = ambssamp * wt + 0.5;
811 greg 2.16 /* assign coefficient */
812 greg 2.14 copycolor(hp->acoef, ac);
813 greg 2.16 d = 1.0/(hp->nt*hp->np);
814     scalecolor(hp->acoef, d);
815 greg 2.14 /* make axes */
816     VCOPY(hp->uz, r->ron);
817     hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
818     for (i = 0; i < 3; i++)
819     if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6)
820     break;
821     if (i >= 3)
822     error(CONSISTENCY, "bad ray direction in inithemi");
823     hp->uy[i] = 1.0;
824     fcross(hp->ux, hp->uy, hp->uz);
825     normalize(hp->ux);
826     fcross(hp->uy, hp->uz, hp->ux);
827 greg 1.1 }
828    
829    
830 greg 2.9 int
831 greg 2.14 divsample( /* sample a division */
832 greg 2.23 AMBSAMP *dp,
833 greg 2.14 AMBHEMI *h,
834     RAY *r
835     )
836 greg 1.1 {
837     RAY ar;
838 greg 1.11 int hlist[3];
839     double spt[2];
840 greg 1.1 double xd, yd, zd;
841     double b2;
842     double phi;
843 greg 2.23 int i;
844 greg 2.15 /* ambient coefficient for weight */
845 greg 2.16 if (ambacc > FTINY)
846     setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
847     else
848     copycolor(ar.rcoef, h->acoef);
849 greg 2.14 if (rayorigin(&ar, AMBIENT, r, ar.rcoef) < 0)
850 greg 1.4 return(-1);
851 greg 2.17 if (ambacc > FTINY) {
852     multcolor(ar.rcoef, h->acoef);
853     scalecolor(ar.rcoef, 1./AVGREFL);
854     }
855 greg 1.1 hlist[0] = r->rno;
856     hlist[1] = dp->t;
857     hlist[2] = dp->p;
858 greg 1.13 multisamp(spt, 2, urand(ilhash(hlist,3)+dp->n));
859 greg 1.11 zd = sqrt((dp->t + spt[0])/h->nt);
860     phi = 2.0*PI * (dp->p + spt[1])/h->np;
861 gwlarson 2.8 xd = tcos(phi) * zd;
862     yd = tsin(phi) * zd;
863 greg 1.1 zd = sqrt(1.0 - zd*zd);
864 greg 1.2 for (i = 0; i < 3; i++)
865     ar.rdir[i] = xd*h->ux[i] +
866     yd*h->uy[i] +
867     zd*h->uz[i];
868 greg 2.22 checknorm(ar.rdir);
869 greg 1.2 dimlist[ndims++] = dp->t*h->np + dp->p + 90171;
870 greg 1.1 rayvalue(&ar);
871     ndims--;
872 greg 2.16 multcolor(ar.rcol, ar.rcoef); /* apply coefficient */
873 greg 1.1 addcolor(dp->v, ar.rcol);
874 greg 2.9 /* use rt to improve gradient calc */
875     if (ar.rt > FTINY && ar.rt < FHUGE)
876     dp->r += 1.0/ar.rt;
877 greg 1.1 /* (re)initialize error */
878     if (dp->n++) {
879     b2 = bright(dp->v)/dp->n - bright(ar.rcol);
880     b2 = b2*b2 + dp->k*((dp->n-1)*(dp->n-1));
881     dp->k = b2/(dp->n*dp->n);
882     } else
883     dp->k = 0.0;
884 greg 1.4 return(0);
885 greg 1.1 }
886    
887    
888 greg 2.14 static int
889     ambcmp( /* decreasing order */
890     const void *p1,
891     const void *p2
892     )
893     {
894     const AMBSAMP *d1 = (const AMBSAMP *)p1;
895     const AMBSAMP *d2 = (const AMBSAMP *)p2;
896    
897     if (d1->k < d2->k)
898     return(1);
899     if (d1->k > d2->k)
900     return(-1);
901     return(0);
902     }
903    
904    
905     static int
906     ambnorm( /* standard order */
907     const void *p1,
908     const void *p2
909     )
910     {
911     const AMBSAMP *d1 = (const AMBSAMP *)p1;
912     const AMBSAMP *d2 = (const AMBSAMP *)p2;
913 greg 2.23 int c;
914 greg 2.14
915     if ( (c = d1->t - d2->t) )
916     return(c);
917     return(d1->p - d2->p);
918     }
919    
920    
921 greg 1.1 double
922 greg 2.14 doambient( /* compute ambient component */
923 greg 2.23 COLOR rcol,
924 greg 2.14 RAY *r,
925     double wt,
926     FVECT pg,
927     FVECT dg
928     )
929 greg 1.1 {
930 greg 2.24 double b, d=0;
931 greg 1.1 AMBHEMI hemi;
932     AMBSAMP *div;
933     AMBSAMP dnew;
934 greg 2.23 double acol[3];
935     AMBSAMP *dp;
936 greg 1.1 double arad;
937 greg 2.19 int divcnt;
938 greg 2.23 int i, j;
939 greg 1.1 /* initialize hemisphere */
940 greg 2.23 inithemi(&hemi, rcol, r, wt);
941 greg 2.19 divcnt = hemi.nt * hemi.np;
942 greg 2.17 /* initialize */
943     if (pg != NULL)
944     pg[0] = pg[1] = pg[2] = 0.0;
945     if (dg != NULL)
946     dg[0] = dg[1] = dg[2] = 0.0;
947 greg 2.23 setcolor(rcol, 0.0, 0.0, 0.0);
948 greg 2.19 if (divcnt == 0)
949 greg 1.1 return(0.0);
950 greg 2.14 /* allocate super-samples */
951 greg 2.15 if (hemi.ns > 0 || pg != NULL || dg != NULL) {
952 greg 2.19 div = (AMBSAMP *)malloc(divcnt*sizeof(AMBSAMP));
953 greg 1.1 if (div == NULL)
954     error(SYSTEM, "out of memory in doambient");
955     } else
956     div = NULL;
957     /* sample the divisions */
958     arad = 0.0;
959 greg 2.23 acol[0] = acol[1] = acol[2] = 0.0;
960 greg 1.1 if ((dp = div) == NULL)
961     dp = &dnew;
962 greg 2.19 divcnt = 0;
963 greg 1.1 for (i = 0; i < hemi.nt; i++)
964     for (j = 0; j < hemi.np; j++) {
965     dp->t = i; dp->p = j;
966     setcolor(dp->v, 0.0, 0.0, 0.0);
967 greg 1.2 dp->r = 0.0;
968 greg 1.1 dp->n = 0;
969 greg 2.16 if (divsample(dp, &hemi, r) < 0) {
970 greg 2.19 if (div != NULL)
971     dp++;
972 greg 2.16 continue;
973     }
974 greg 2.6 arad += dp->r;
975 greg 2.19 divcnt++;
976 greg 1.1 if (div != NULL)
977     dp++;
978 greg 2.6 else
979 greg 1.1 addcolor(acol, dp->v);
980     }
981 greg 2.21 if (!divcnt) {
982     if (div != NULL)
983     free((void *)div);
984 greg 2.19 return(0.0); /* no samples taken */
985 greg 2.21 }
986 greg 2.19 if (divcnt < hemi.nt*hemi.np) {
987     pg = dg = NULL; /* incomplete sampling */
988     hemi.ns = 0;
989     } else if (arad > FTINY && divcnt/arad < minarad) {
990 greg 2.15 hemi.ns = 0; /* close enough */
991 greg 2.19 } else if (hemi.ns > 0) { /* else perform super-sampling? */
992 greg 1.4 comperrs(div, &hemi); /* compute errors */
993 greg 2.19 qsort(div, divcnt, sizeof(AMBSAMP), ambcmp); /* sort divs */
994 greg 1.1 /* super-sample */
995 greg 2.15 for (i = hemi.ns; i > 0; i--) {
996 schorsch 2.11 dnew = *div;
997 greg 2.16 if (divsample(&dnew, &hemi, r) < 0) {
998     dp++;
999     continue;
1000     }
1001     dp = div; /* reinsert */
1002 greg 2.19 j = divcnt < i ? divcnt : i;
1003 greg 1.1 while (--j > 0 && dnew.k < dp[1].k) {
1004 schorsch 2.11 *dp = *(dp+1);
1005 greg 1.1 dp++;
1006     }
1007 schorsch 2.11 *dp = dnew;
1008 greg 1.1 }
1009 greg 1.2 if (pg != NULL || dg != NULL) /* restore order */
1010 greg 2.19 qsort(div, divcnt, sizeof(AMBSAMP), ambnorm);
1011 greg 1.1 }
1012     /* compute returned values */
1013 greg 1.3 if (div != NULL) {
1014 greg 2.19 arad = 0.0; /* note: divcnt may be < nt*np */
1015     for (i = hemi.nt*hemi.np, dp = div; i-- > 0; dp++) {
1016 greg 1.3 arad += dp->r;
1017     if (dp->n > 1) {
1018     b = 1.0/dp->n;
1019     scalecolor(dp->v, b);
1020     dp->r *= b;
1021     dp->n = 1;
1022     }
1023     addcolor(acol, dp->v);
1024     }
1025 greg 1.5 b = bright(acol);
1026 greg 1.6 if (b > FTINY) {
1027 greg 2.17 b = 1.0/b; /* compute & normalize gradient(s) */
1028 greg 1.6 if (pg != NULL) {
1029     posgradient(pg, div, &hemi);
1030     for (i = 0; i < 3; i++)
1031     pg[i] *= b;
1032     }
1033     if (dg != NULL) {
1034     dirgradient(dg, div, &hemi);
1035     for (i = 0; i < 3; i++)
1036     dg[i] *= b;
1037     }
1038 greg 1.5 }
1039 greg 2.9 free((void *)div);
1040 greg 1.3 }
1041 greg 2.23 copycolor(rcol, acol);
1042 greg 1.1 if (arad <= FTINY)
1043 greg 1.16 arad = maxarad;
1044 greg 2.3 else
1045 greg 2.19 arad = (divcnt+hemi.ns)/arad;
1046 greg 1.15 if (pg != NULL) { /* reduce radius if gradient large */
1047     d = DOT(pg,pg);
1048     if (d*arad*arad > 1.0)
1049     arad = 1.0/sqrt(d);
1050     }
1051 greg 1.16 if (arad < minarad) {
1052 greg 1.1 arad = minarad;
1053 greg 1.16 if (pg != NULL && d*arad*arad > 1.0) { /* cap gradient */
1054     d = 1.0/arad/sqrt(d);
1055     for (i = 0; i < 3; i++)
1056     pg[i] *= d;
1057     }
1058     }
1059 greg 2.3 if ((arad /= sqrt(wt)) > maxarad)
1060     arad = maxarad;
1061     return(arad);
1062 greg 1.1 }
1063    
1064    
1065 greg 2.9 void
1066 greg 2.14 comperrs( /* compute initial error estimates */
1067     AMBSAMP *da, /* assumes standard ordering */
1068 greg 2.23 AMBHEMI *hp
1069 greg 2.14 )
1070 greg 1.1 {
1071     double b, b2;
1072     int i, j;
1073 greg 2.23 AMBSAMP *dp;
1074 greg 1.1 /* sum differences from neighbors */
1075     dp = da;
1076     for (i = 0; i < hp->nt; i++)
1077     for (j = 0; j < hp->np; j++) {
1078 greg 1.6 #ifdef DEBUG
1079     if (dp->t != i || dp->p != j)
1080     error(CONSISTENCY,
1081     "division order in comperrs");
1082     #endif
1083 greg 1.1 b = bright(dp[0].v);
1084     if (i > 0) { /* from above */
1085     b2 = bright(dp[-hp->np].v) - b;
1086     b2 *= b2 * 0.25;
1087     dp[0].k += b2;
1088     dp[-hp->np].k += b2;
1089     }
1090     if (j > 0) { /* from behind */
1091     b2 = bright(dp[-1].v) - b;
1092     b2 *= b2 * 0.25;
1093     dp[0].k += b2;
1094     dp[-1].k += b2;
1095 greg 1.4 } else { /* around */
1096     b2 = bright(dp[hp->np-1].v) - b;
1097 greg 1.1 b2 *= b2 * 0.25;
1098     dp[0].k += b2;
1099 greg 1.4 dp[hp->np-1].k += b2;
1100 greg 1.1 }
1101     dp++;
1102     }
1103     /* divide by number of neighbors */
1104     dp = da;
1105     for (j = 0; j < hp->np; j++) /* top row */
1106     (dp++)->k *= 1.0/3.0;
1107     if (hp->nt < 2)
1108     return;
1109     for (i = 1; i < hp->nt-1; i++) /* central region */
1110     for (j = 0; j < hp->np; j++)
1111     (dp++)->k *= 0.25;
1112     for (j = 0; j < hp->np; j++) /* bottom row */
1113     (dp++)->k *= 1.0/3.0;
1114     }
1115    
1116    
1117 greg 2.9 void
1118 greg 2.14 posgradient( /* compute position gradient */
1119     FVECT gv,
1120     AMBSAMP *da, /* assumes standard ordering */
1121 greg 2.23 AMBHEMI *hp
1122 greg 2.14 )
1123 greg 1.1 {
1124 greg 2.23 int i, j;
1125 greg 2.2 double nextsine, lastsine, b, d;
1126 greg 1.2 double mag0, mag1;
1127     double phi, cosp, sinp, xd, yd;
1128 greg 2.23 AMBSAMP *dp;
1129 greg 1.2
1130     xd = yd = 0.0;
1131     for (j = 0; j < hp->np; j++) {
1132     dp = da + j;
1133     mag0 = mag1 = 0.0;
1134 greg 2.2 lastsine = 0.0;
1135 greg 1.2 for (i = 0; i < hp->nt; i++) {
1136     #ifdef DEBUG
1137     if (dp->t != i || dp->p != j)
1138     error(CONSISTENCY,
1139     "division order in posgradient");
1140     #endif
1141     b = bright(dp->v);
1142     if (i > 0) {
1143     d = dp[-hp->np].r;
1144     if (dp[0].r > d) d = dp[0].r;
1145 greg 2.2 /* sin(t)*cos(t)^2 */
1146     d *= lastsine * (1.0 - (double)i/hp->nt);
1147 greg 1.2 mag0 += d*(b - bright(dp[-hp->np].v));
1148     }
1149 greg 2.2 nextsine = sqrt((double)(i+1)/hp->nt);
1150 greg 1.2 if (j > 0) {
1151     d = dp[-1].r;
1152     if (dp[0].r > d) d = dp[0].r;
1153 greg 2.2 mag1 += d * (nextsine - lastsine) *
1154     (b - bright(dp[-1].v));
1155 greg 1.2 } else {
1156     d = dp[hp->np-1].r;
1157     if (dp[0].r > d) d = dp[0].r;
1158 greg 2.2 mag1 += d * (nextsine - lastsine) *
1159     (b - bright(dp[hp->np-1].v));
1160 greg 1.2 }
1161     dp += hp->np;
1162 greg 2.2 lastsine = nextsine;
1163 greg 1.2 }
1164 greg 2.2 mag0 *= 2.0*PI / hp->np;
1165 greg 1.2 phi = 2.0*PI * (double)j/hp->np;
1166 gwlarson 2.8 cosp = tcos(phi); sinp = tsin(phi);
1167 greg 1.2 xd += mag0*cosp - mag1*sinp;
1168     yd += mag0*sinp + mag1*cosp;
1169     }
1170     for (i = 0; i < 3; i++)
1171 greg 2.16 gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])*(hp->nt*hp->np)/PI;
1172 greg 1.1 }
1173    
1174    
1175 greg 2.9 void
1176 greg 2.14 dirgradient( /* compute direction gradient */
1177     FVECT gv,
1178     AMBSAMP *da, /* assumes standard ordering */
1179 greg 2.23 AMBHEMI *hp
1180 greg 2.14 )
1181 greg 1.1 {
1182 greg 2.23 int i, j;
1183 greg 1.2 double mag;
1184     double phi, xd, yd;
1185 greg 2.23 AMBSAMP *dp;
1186 greg 1.2
1187     xd = yd = 0.0;
1188     for (j = 0; j < hp->np; j++) {
1189     dp = da + j;
1190     mag = 0.0;
1191     for (i = 0; i < hp->nt; i++) {
1192     #ifdef DEBUG
1193     if (dp->t != i || dp->p != j)
1194     error(CONSISTENCY,
1195     "division order in dirgradient");
1196     #endif
1197 greg 2.2 /* tan(t) */
1198     mag += bright(dp->v)/sqrt(hp->nt/(i+.5) - 1.0);
1199 greg 1.2 dp += hp->np;
1200     }
1201     phi = 2.0*PI * (j+.5)/hp->np + PI/2.0;
1202 gwlarson 2.8 xd += mag * tcos(phi);
1203     yd += mag * tsin(phi);
1204 greg 1.2 }
1205     for (i = 0; i < 3; i++)
1206 greg 2.16 gv[i] = xd*hp->ux[i] + yd*hp->uy[i];
1207 greg 1.1 }
1208 greg 2.25
1209     #endif /* ! NEWAMB */