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root/radiance/ray/src/rt/ambcomp.c
Revision: 2.61
Committed: Sun May 18 18:59:55 2014 UTC (9 years, 11 months ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 2.60: +131 -133 lines
Log Message:
Reorganized calculation now storing average division value & min. distance

File Contents

# User Rev Content
1 greg 1.1 #ifndef lint
2 greg 2.61 static const char RCSid[] = "$Id: ambcomp.c,v 2.60 2014/05/17 00:49:17 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 2.25 #ifdef NEWAMB
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     ambsample( /* initial ambient division sample */
55     AMBHEMI *hp,
56     int i,
57     int j,
58     int n
59 greg 2.26 )
60     {
61 greg 2.61 AMBSAMP *ap = &ambsam(hp,i,j);
62     RAY ar;
63 greg 2.41 int hlist[3], ii;
64     double spt[2], zd;
65 greg 2.61 /* generate hemispherical sample */
66 greg 2.26 /* ambient coefficient for weight */
67     if (ambacc > FTINY)
68 greg 2.61 setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
69 greg 2.26 else
70 greg 2.61 copycolor(ar.rcoef, hp->acoef);
71     if (rayorigin(&ar, AMBIENT, hp->rp, ar.rcoef) < 0) {
72     if (!n) memset(ap, 0, sizeof(AMBSAMP));
73 greg 2.41 return(0);
74 greg 2.61 }
75 greg 2.26 if (ambacc > FTINY) {
76 greg 2.61 multcolor(ar.rcoef, hp->acoef);
77     scalecolor(ar.rcoef, 1./AVGREFL);
78 greg 2.41 }
79     hlist[0] = hp->rp->rno;
80 greg 2.46 hlist[1] = j;
81     hlist[2] = i;
82 greg 2.41 multisamp(spt, 2, urand(ilhash(hlist,3)+n));
83     if (!n) { /* avoid border samples for n==0 */
84 greg 2.46 if ((spt[0] < 0.1) | (spt[0] >= 0.9))
85 greg 2.41 spt[0] = 0.1 + 0.8*frandom();
86 greg 2.46 if ((spt[1] < 0.1) | (spt[1] >= 0.9))
87 greg 2.41 spt[1] = 0.1 + 0.8*frandom();
88 greg 2.26 }
89 greg 2.46 SDsquare2disk(spt, (j+spt[1])/hp->ns, (i+spt[0])/hp->ns);
90 greg 2.26 zd = sqrt(1. - spt[0]*spt[0] - spt[1]*spt[1]);
91     for (ii = 3; ii--; )
92 greg 2.61 ar.rdir[ii] = spt[0]*hp->ux[ii] +
93 greg 2.26 spt[1]*hp->uy[ii] +
94     zd*hp->rp->ron[ii];
95 greg 2.61 checknorm(ar.rdir);
96 greg 2.56 dimlist[ndims++] = AI(hp,i,j) + 90171;
97 greg 2.61 rayvalue(&ar); /* evaluate ray */
98     ndims--;
99     if (ar.rt <= FTINY)
100     return(0); /* should never happen */
101     multcolor(ar.rcol, ar.rcoef); /* apply coefficient */
102     if (!n || ar.rt*ap->d < 1.0) /* new/closer distance? */
103     ap->d = 1.0/ar.rt;
104     if (!n) { /* record first vertex & value */
105     if (ar.rt > 10.0*thescene.cusize)
106     ar.rt = 10.0*thescene.cusize;
107     VSUM(ap->p, ar.rorg, ar.rdir, ar.rt);
108     copycolor(ap->v, ar.rcol);
109     } else { /* else update recorded value */
110     hp->acol[RED] -= colval(ap->v,RED);
111     hp->acol[GRN] -= colval(ap->v,GRN);
112     hp->acol[BLU] -= colval(ap->v,BLU);
113     zd = 1.0/(double)(n+1);
114     scalecolor(ar.rcol, zd);
115     zd *= (double)n;
116     scalecolor(ap->v, zd);
117     addcolor(ap->v, ar.rcol);
118     }
119     addcolor(hp->acol, ap->v); /* add to our sum */
120 greg 2.41 return(1);
121     }
122    
123    
124     /* Estimate errors based on ambient division differences */
125     static float *
126     getambdiffs(AMBHEMI *hp)
127     {
128 greg 2.55 float *earr = (float *)calloc(hp->ns*hp->ns, sizeof(float));
129 greg 2.41 float *ep;
130 greg 2.42 AMBSAMP *ap;
131 greg 2.41 double b, d2;
132     int i, j;
133    
134     if (earr == NULL) /* out of memory? */
135     return(NULL);
136     /* compute squared neighbor diffs */
137 greg 2.42 for (ap = hp->sa, ep = earr, i = 0; i < hp->ns; i++)
138     for (j = 0; j < hp->ns; j++, ap++, ep++) {
139     b = bright(ap[0].v);
140 greg 2.41 if (i) { /* from above */
141 greg 2.42 d2 = b - bright(ap[-hp->ns].v);
142 greg 2.41 d2 *= d2;
143     ep[0] += d2;
144     ep[-hp->ns] += d2;
145     }
146 greg 2.55 if (!j) continue;
147     /* from behind */
148     d2 = b - bright(ap[-1].v);
149     d2 *= d2;
150     ep[0] += d2;
151     ep[-1] += d2;
152     if (!i) continue;
153     /* diagonal */
154     d2 = b - bright(ap[-hp->ns-1].v);
155     d2 *= d2;
156     ep[0] += d2;
157     ep[-hp->ns-1] += d2;
158 greg 2.41 }
159     /* correct for number of neighbors */
160 greg 2.55 earr[0] *= 8./3.;
161     earr[hp->ns-1] *= 8./3.;
162     earr[(hp->ns-1)*hp->ns] *= 8./3.;
163     earr[(hp->ns-1)*hp->ns + hp->ns-1] *= 8./3.;
164 greg 2.41 for (i = 1; i < hp->ns-1; i++) {
165 greg 2.55 earr[i*hp->ns] *= 8./5.;
166     earr[i*hp->ns + hp->ns-1] *= 8./5.;
167 greg 2.41 }
168     for (j = 1; j < hp->ns-1; j++) {
169 greg 2.55 earr[j] *= 8./5.;
170     earr[(hp->ns-1)*hp->ns + j] *= 8./5.;
171 greg 2.41 }
172     return(earr);
173     }
174    
175    
176 greg 2.43 /* Perform super-sampling on hemisphere (introduces bias) */
177 greg 2.41 static void
178 greg 2.61 ambsupersamp(AMBHEMI *hp, int cnt)
179 greg 2.41 {
180     float *earr = getambdiffs(hp);
181 greg 2.54 double e2rem = 0;
182 greg 2.41 AMBSAMP *ap;
183     RAY ar;
184     float *ep;
185 greg 2.55 int i, j, n, nss;
186 greg 2.41
187     if (earr == NULL) /* just skip calc. if no memory */
188     return;
189 greg 2.54 /* accumulate estimated variances */
190 greg 2.55 for (ep = earr + hp->ns*hp->ns; ep > earr; )
191     e2rem += *--ep;
192 greg 2.41 ep = earr; /* perform super-sampling */
193     for (ap = hp->sa, i = 0; i < hp->ns; i++)
194     for (j = 0; j < hp->ns; j++, ap++) {
195 greg 2.55 if (e2rem <= FTINY)
196     goto done; /* nothing left to do */
197     nss = *ep/e2rem*cnt + frandom();
198 greg 2.61 for (n = 1; n <= nss; n++)
199     cnt -= ambsample(hp, i, j, n);
200     e2rem -= *ep++; /* update remainder */
201 greg 2.41 }
202 greg 2.55 done:
203 greg 2.41 free(earr);
204     }
205    
206    
207 greg 2.61 static AMBHEMI *
208     samp_hemi( /* sample indirect hemisphere */
209     COLOR rcol,
210     RAY *r,
211     double wt
212     )
213     {
214     AMBHEMI *hp;
215     double d;
216     int n, i, j;
217     /* set number of divisions */
218     if (ambacc <= FTINY &&
219     wt > (d = 0.8*intens(rcol)*r->rweight/(ambdiv*minweight)))
220     wt = d; /* avoid ray termination */
221     n = sqrt(ambdiv * wt) + 0.5;
222     i = 1 + 5*(ambacc > FTINY); /* minimum number of samples */
223     if (n < i)
224     n = i;
225     /* allocate sampling array */
226     hp = (AMBHEMI *)malloc(sizeof(AMBHEMI) + sizeof(AMBSAMP)*(n*n - 1));
227     if (hp == NULL)
228     error(SYSTEM, "out of memory in samp_hemi");
229     hp->rp = r;
230     hp->ns = n;
231     hp->acol[RED] = hp->acol[GRN] = hp->acol[BLU] = 0.0;
232     hp->sampOK = 0;
233     /* assign coefficient */
234     copycolor(hp->acoef, rcol);
235     d = 1.0/(n*n);
236     scalecolor(hp->acoef, d);
237     /* make tangent plane axes */
238     hp->uy[0] = 0.5 - frandom();
239     hp->uy[1] = 0.5 - frandom();
240     hp->uy[2] = 0.5 - frandom();
241     for (i = 3; i--; )
242     if ((-0.6 < r->ron[i]) & (r->ron[i] < 0.6))
243     break;
244     if (i < 0)
245     error(CONSISTENCY, "bad ray direction in samp_hemi");
246     hp->uy[i] = 1.0;
247     VCROSS(hp->ux, hp->uy, r->ron);
248     normalize(hp->ux);
249     VCROSS(hp->uy, r->ron, hp->ux);
250     /* sample divisions */
251     for (i = hp->ns; i--; )
252     for (j = hp->ns; j--; )
253     hp->sampOK += ambsample(hp, i, j, 0);
254     copycolor(rcol, hp->acol);
255     if (!hp->sampOK) { /* utter failure? */
256     free(hp);
257     return(NULL);
258     }
259     if (hp->sampOK < hp->ns*hp->ns) {
260     hp->sampOK *= -1; /* soft failure */
261     return(hp);
262     }
263     n = ambssamp*wt + 0.5;
264     if (n > 8) { /* perform super-sampling? */
265     ambsupersamp(hp, n);
266     copycolor(rcol, hp->acol);
267     }
268     return(hp); /* all is well */
269     }
270    
271    
272 greg 2.46 /* Return brightness of farthest ambient sample */
273     static double
274 greg 2.56 back_ambval(AMBHEMI *hp, const int n1, const int n2, const int n3)
275 greg 2.46 {
276 greg 2.56 if (hp->sa[n1].d <= hp->sa[n2].d) {
277     if (hp->sa[n1].d <= hp->sa[n3].d)
278     return(colval(hp->sa[n1].v,CIEY));
279     return(colval(hp->sa[n3].v,CIEY));
280     }
281     if (hp->sa[n2].d <= hp->sa[n3].d)
282     return(colval(hp->sa[n2].v,CIEY));
283     return(colval(hp->sa[n3].v,CIEY));
284 greg 2.46 }
285    
286    
287 greg 2.27 /* Compute vectors and coefficients for Hessian/gradient calcs */
288     static void
289 greg 2.56 comp_fftri(FFTRI *ftp, AMBHEMI *hp, const int n0, const int n1)
290 greg 2.27 {
291 greg 2.56 double rdot_cp, dot_e, dot_er, rdot_r, rdot_r1, J2;
292     int ii;
293    
294     VSUB(ftp->r_i, hp->sa[n0].p, hp->rp->rop);
295     VSUB(ftp->r_i1, hp->sa[n1].p, hp->rp->rop);
296     VSUB(ftp->e_i, hp->sa[n1].p, hp->sa[n0].p);
297 greg 2.35 VCROSS(ftp->rcp, ftp->r_i, ftp->r_i1);
298     rdot_cp = 1.0/DOT(ftp->rcp,ftp->rcp);
299 greg 2.27 dot_e = DOT(ftp->e_i,ftp->e_i);
300     dot_er = DOT(ftp->e_i, ftp->r_i);
301 greg 2.32 rdot_r = 1.0/DOT(ftp->r_i,ftp->r_i);
302     rdot_r1 = 1.0/DOT(ftp->r_i1,ftp->r_i1);
303     ftp->I1 = acos( DOT(ftp->r_i, ftp->r_i1) * sqrt(rdot_r*rdot_r1) ) *
304 greg 2.35 sqrt( rdot_cp );
305 greg 2.32 ftp->I2 = ( DOT(ftp->e_i, ftp->r_i1)*rdot_r1 - dot_er*rdot_r +
306 greg 2.35 dot_e*ftp->I1 )*0.5*rdot_cp;
307 greg 2.32 J2 = ( 0.5*(rdot_r - rdot_r1) - dot_er*ftp->I2 ) / dot_e;
308 greg 2.46 for (ii = 3; ii--; )
309     ftp->rI2_eJ2[ii] = ftp->I2*ftp->r_i[ii] + J2*ftp->e_i[ii];
310 greg 2.27 }
311    
312    
313 greg 2.28 /* Compose 3x3 matrix from two vectors */
314 greg 2.27 static void
315     compose_matrix(FVECT mat[3], FVECT va, FVECT vb)
316     {
317     mat[0][0] = 2.0*va[0]*vb[0];
318     mat[1][1] = 2.0*va[1]*vb[1];
319     mat[2][2] = 2.0*va[2]*vb[2];
320     mat[0][1] = mat[1][0] = va[0]*vb[1] + va[1]*vb[0];
321     mat[0][2] = mat[2][0] = va[0]*vb[2] + va[2]*vb[0];
322     mat[1][2] = mat[2][1] = va[1]*vb[2] + va[2]*vb[1];
323     }
324    
325    
326     /* Compute partial 3x3 Hessian matrix for edge */
327     static void
328     comp_hessian(FVECT hess[3], FFTRI *ftp, FVECT nrm)
329     {
330 greg 2.35 FVECT ncp;
331 greg 2.27 FVECT m1[3], m2[3], m3[3], m4[3];
332     double d1, d2, d3, d4;
333     double I3, J3, K3;
334     int i, j;
335     /* compute intermediate coefficients */
336     d1 = 1.0/DOT(ftp->r_i,ftp->r_i);
337     d2 = 1.0/DOT(ftp->r_i1,ftp->r_i1);
338     d3 = 1.0/DOT(ftp->e_i,ftp->e_i);
339     d4 = DOT(ftp->e_i, ftp->r_i);
340 greg 2.35 I3 = ( DOT(ftp->e_i, ftp->r_i1)*d2*d2 - d4*d1*d1 + 3.0/d3*ftp->I2 )
341     / ( 4.0*DOT(ftp->rcp,ftp->rcp) );
342 greg 2.27 J3 = 0.25*d3*(d1*d1 - d2*d2) - d4*d3*I3;
343     K3 = d3*(ftp->I2 - I3/d1 - 2.0*d4*J3);
344     /* intermediate matrices */
345 greg 2.35 VCROSS(ncp, nrm, ftp->e_i);
346     compose_matrix(m1, ncp, ftp->rI2_eJ2);
347 greg 2.27 compose_matrix(m2, ftp->r_i, ftp->r_i);
348     compose_matrix(m3, ftp->e_i, ftp->e_i);
349     compose_matrix(m4, ftp->r_i, ftp->e_i);
350 greg 2.35 d1 = DOT(nrm, ftp->rcp);
351 greg 2.27 d2 = -d1*ftp->I2;
352     d1 *= 2.0;
353     for (i = 3; i--; ) /* final matrix sum */
354     for (j = 3; j--; ) {
355     hess[i][j] = m1[i][j] + d1*( I3*m2[i][j] + K3*m3[i][j] +
356     2.0*J3*m4[i][j] );
357     hess[i][j] += d2*(i==j);
358 greg 2.46 hess[i][j] *= -1.0/PI;
359 greg 2.27 }
360     }
361    
362    
363     /* Reverse hessian calculation result for edge in other direction */
364     static void
365     rev_hessian(FVECT hess[3])
366     {
367     int i;
368    
369     for (i = 3; i--; ) {
370     hess[i][0] = -hess[i][0];
371     hess[i][1] = -hess[i][1];
372     hess[i][2] = -hess[i][2];
373     }
374     }
375    
376    
377     /* Add to radiometric Hessian from the given triangle */
378     static void
379     add2hessian(FVECT hess[3], FVECT ehess1[3],
380 greg 2.46 FVECT ehess2[3], FVECT ehess3[3], double v)
381 greg 2.27 {
382     int i, j;
383    
384     for (i = 3; i--; )
385     for (j = 3; j--; )
386     hess[i][j] += v*( ehess1[i][j] + ehess2[i][j] + ehess3[i][j] );
387     }
388    
389    
390     /* Compute partial displacement form factor gradient for edge */
391     static void
392     comp_gradient(FVECT grad, FFTRI *ftp, FVECT nrm)
393     {
394 greg 2.35 FVECT ncp;
395 greg 2.27 double f1;
396     int i;
397    
398 greg 2.35 f1 = 2.0*DOT(nrm, ftp->rcp);
399     VCROSS(ncp, nrm, ftp->e_i);
400 greg 2.27 for (i = 3; i--; )
401 greg 2.46 grad[i] = (0.5/PI)*( ftp->I1*ncp[i] + f1*ftp->rI2_eJ2[i] );
402 greg 2.27 }
403    
404    
405     /* Reverse gradient calculation result for edge in other direction */
406     static void
407     rev_gradient(FVECT grad)
408     {
409     grad[0] = -grad[0];
410     grad[1] = -grad[1];
411     grad[2] = -grad[2];
412     }
413    
414    
415     /* Add to displacement gradient from the given triangle */
416     static void
417 greg 2.46 add2gradient(FVECT grad, FVECT egrad1, FVECT egrad2, FVECT egrad3, double v)
418 greg 2.27 {
419     int i;
420    
421     for (i = 3; i--; )
422     grad[i] += v*( egrad1[i] + egrad2[i] + egrad3[i] );
423     }
424    
425    
426     /* Compute anisotropic radii and eigenvector directions */
427 greg 2.53 static void
428 greg 2.27 eigenvectors(FVECT uv[2], float ra[2], FVECT hessian[3])
429     {
430     double hess2[2][2];
431     FVECT a, b;
432     double evalue[2], slope1, xmag1;
433     int i;
434     /* project Hessian to sample plane */
435     for (i = 3; i--; ) {
436     a[i] = DOT(hessian[i], uv[0]);
437     b[i] = DOT(hessian[i], uv[1]);
438     }
439     hess2[0][0] = DOT(uv[0], a);
440     hess2[0][1] = DOT(uv[0], b);
441     hess2[1][0] = DOT(uv[1], a);
442     hess2[1][1] = DOT(uv[1], b);
443 greg 2.38 /* compute eigenvalue(s) */
444     i = quadratic(evalue, 1.0, -hess2[0][0]-hess2[1][1],
445     hess2[0][0]*hess2[1][1]-hess2[0][1]*hess2[1][0]);
446     if (i == 1) /* double-root (circle) */
447     evalue[1] = evalue[0];
448     if (!i || ((evalue[0] = fabs(evalue[0])) <= FTINY*FTINY) |
449 greg 2.53 ((evalue[1] = fabs(evalue[1])) <= FTINY*FTINY) ) {
450     ra[0] = ra[1] = maxarad;
451     return;
452     }
453 greg 2.27 if (evalue[0] > evalue[1]) {
454 greg 2.29 ra[0] = sqrt(sqrt(4.0/evalue[0]));
455     ra[1] = sqrt(sqrt(4.0/evalue[1]));
456 greg 2.27 slope1 = evalue[1];
457     } else {
458 greg 2.29 ra[0] = sqrt(sqrt(4.0/evalue[1]));
459     ra[1] = sqrt(sqrt(4.0/evalue[0]));
460 greg 2.27 slope1 = evalue[0];
461     }
462     /* compute unit eigenvectors */
463     if (fabs(hess2[0][1]) <= FTINY)
464     return; /* uv OK as is */
465     slope1 = (slope1 - hess2[0][0]) / hess2[0][1];
466     xmag1 = sqrt(1.0/(1.0 + slope1*slope1));
467     for (i = 3; i--; ) {
468     b[i] = xmag1*uv[0][i] + slope1*xmag1*uv[1][i];
469     a[i] = slope1*xmag1*uv[0][i] - xmag1*uv[1][i];
470     }
471     VCOPY(uv[0], a);
472     VCOPY(uv[1], b);
473     }
474    
475    
476 greg 2.26 static void
477     ambHessian( /* anisotropic radii & pos. gradient */
478     AMBHEMI *hp,
479     FVECT uv[2], /* returned */
480 greg 2.28 float ra[2], /* returned (optional) */
481     float pg[2] /* returned (optional) */
482 greg 2.26 )
483     {
484 greg 2.27 static char memerrmsg[] = "out of memory in ambHessian()";
485     FVECT (*hessrow)[3] = NULL;
486     FVECT *gradrow = NULL;
487     FVECT hessian[3];
488     FVECT gradient;
489     FFTRI fftr;
490     int i, j;
491     /* be sure to assign unit vectors */
492     VCOPY(uv[0], hp->ux);
493     VCOPY(uv[1], hp->uy);
494     /* clock-wise vertex traversal from sample POV */
495     if (ra != NULL) { /* initialize Hessian row buffer */
496 greg 2.28 hessrow = (FVECT (*)[3])malloc(sizeof(FVECT)*3*(hp->ns-1));
497 greg 2.27 if (hessrow == NULL)
498     error(SYSTEM, memerrmsg);
499     memset(hessian, 0, sizeof(hessian));
500     } else if (pg == NULL) /* bogus call? */
501     return;
502     if (pg != NULL) { /* initialize form factor row buffer */
503 greg 2.28 gradrow = (FVECT *)malloc(sizeof(FVECT)*(hp->ns-1));
504 greg 2.27 if (gradrow == NULL)
505     error(SYSTEM, memerrmsg);
506     memset(gradient, 0, sizeof(gradient));
507     }
508     /* compute first row of edges */
509     for (j = 0; j < hp->ns-1; j++) {
510 greg 2.56 comp_fftri(&fftr, hp, AI(hp,0,j), AI(hp,0,j+1));
511 greg 2.27 if (hessrow != NULL)
512     comp_hessian(hessrow[j], &fftr, hp->rp->ron);
513     if (gradrow != NULL)
514     comp_gradient(gradrow[j], &fftr, hp->rp->ron);
515     }
516     /* sum each row of triangles */
517     for (i = 0; i < hp->ns-1; i++) {
518     FVECT hesscol[3]; /* compute first vertical edge */
519     FVECT gradcol;
520 greg 2.56 comp_fftri(&fftr, hp, AI(hp,i,0), AI(hp,i+1,0));
521 greg 2.27 if (hessrow != NULL)
522     comp_hessian(hesscol, &fftr, hp->rp->ron);
523     if (gradrow != NULL)
524     comp_gradient(gradcol, &fftr, hp->rp->ron);
525     for (j = 0; j < hp->ns-1; j++) {
526     FVECT hessdia[3]; /* compute triangle contributions */
527     FVECT graddia;
528 greg 2.46 double backg;
529 greg 2.56 backg = back_ambval(hp, AI(hp,i,j),
530     AI(hp,i,j+1), AI(hp,i+1,j));
531 greg 2.27 /* diagonal (inner) edge */
532 greg 2.56 comp_fftri(&fftr, hp, AI(hp,i,j+1), AI(hp,i+1,j));
533 greg 2.27 if (hessrow != NULL) {
534     comp_hessian(hessdia, &fftr, hp->rp->ron);
535     rev_hessian(hesscol);
536     add2hessian(hessian, hessrow[j], hessdia, hesscol, backg);
537     }
538 greg 2.39 if (gradrow != NULL) {
539 greg 2.27 comp_gradient(graddia, &fftr, hp->rp->ron);
540     rev_gradient(gradcol);
541     add2gradient(gradient, gradrow[j], graddia, gradcol, backg);
542     }
543     /* initialize edge in next row */
544 greg 2.56 comp_fftri(&fftr, hp, AI(hp,i+1,j+1), AI(hp,i+1,j));
545 greg 2.27 if (hessrow != NULL)
546     comp_hessian(hessrow[j], &fftr, hp->rp->ron);
547     if (gradrow != NULL)
548     comp_gradient(gradrow[j], &fftr, hp->rp->ron);
549     /* new column edge & paired triangle */
550 greg 2.56 backg = back_ambval(hp, AI(hp,i+1,j+1),
551     AI(hp,i+1,j), AI(hp,i,j+1));
552     comp_fftri(&fftr, hp, AI(hp,i,j+1), AI(hp,i+1,j+1));
553 greg 2.27 if (hessrow != NULL) {
554     comp_hessian(hesscol, &fftr, hp->rp->ron);
555     rev_hessian(hessdia);
556     add2hessian(hessian, hessrow[j], hessdia, hesscol, backg);
557     if (i < hp->ns-2)
558     rev_hessian(hessrow[j]);
559     }
560     if (gradrow != NULL) {
561     comp_gradient(gradcol, &fftr, hp->rp->ron);
562     rev_gradient(graddia);
563     add2gradient(gradient, gradrow[j], graddia, gradcol, backg);
564     if (i < hp->ns-2)
565     rev_gradient(gradrow[j]);
566     }
567     }
568     }
569     /* release row buffers */
570     if (hessrow != NULL) free(hessrow);
571     if (gradrow != NULL) free(gradrow);
572    
573     if (ra != NULL) /* extract eigenvectors & radii */
574     eigenvectors(uv, ra, hessian);
575 greg 2.32 if (pg != NULL) { /* tangential position gradient */
576     pg[0] = DOT(gradient, uv[0]);
577     pg[1] = DOT(gradient, uv[1]);
578 greg 2.27 }
579     }
580    
581    
582     /* Compute direction gradient from a hemispherical sampling */
583     static void
584     ambdirgrad(AMBHEMI *hp, FVECT uv[2], float dg[2])
585     {
586 greg 2.41 AMBSAMP *ap;
587     double dgsum[2];
588     int n;
589     FVECT vd;
590     double gfact;
591 greg 2.27
592 greg 2.29 dgsum[0] = dgsum[1] = 0.0; /* sum values times -tan(theta) */
593 greg 2.27 for (ap = hp->sa, n = hp->ns*hp->ns; n--; ap++) {
594     /* use vector for azimuth + 90deg */
595     VSUB(vd, ap->p, hp->rp->rop);
596 greg 2.29 /* brightness over cosine factor */
597     gfact = colval(ap->v,CIEY) / DOT(hp->rp->ron, vd);
598 greg 2.40 /* sine = proj_radius/vd_length */
599     dgsum[0] -= DOT(uv[1], vd) * gfact;
600     dgsum[1] += DOT(uv[0], vd) * gfact;
601 greg 2.26 }
602 greg 2.29 dg[0] = dgsum[0] / (hp->ns*hp->ns);
603     dg[1] = dgsum[1] / (hp->ns*hp->ns);
604 greg 2.26 }
605    
606 greg 2.27
607 greg 2.49 /* Compute potential light leak direction flags for cache value */
608     static uint32
609     ambcorral(AMBHEMI *hp, FVECT uv[2], const double r0, const double r1)
610 greg 2.47 {
611 greg 2.50 const double max_d = 1.0/(minarad*ambacc + 0.001);
612     const double ang_res = 0.5*PI/(hp->ns-1);
613     const double ang_step = ang_res/((int)(16/PI*ang_res) + (1+FTINY));
614 greg 2.51 double avg_d = 0;
615 greg 2.50 uint32 flgs = 0;
616 greg 2.58 FVECT vec;
617 greg 2.61 double d, u, v;
618 greg 2.58 double ang, a1;
619 greg 2.50 int i, j;
620 greg 2.52 /* don't bother for a few samples */
621     if (hp->ns < 12)
622     return(0);
623     /* check distances overhead */
624 greg 2.51 for (i = hp->ns*3/4; i-- > hp->ns>>2; )
625     for (j = hp->ns*3/4; j-- > hp->ns>>2; )
626     avg_d += ambsam(hp,i,j).d;
627     avg_d *= 4.0/(hp->ns*hp->ns);
628 greg 2.52 if (avg_d*r0 >= 1.0) /* ceiling too low for corral? */
629     return(0);
630     if (avg_d >= max_d) /* insurance */
631 greg 2.51 return(0);
632     /* else circle around perimeter */
633 greg 2.47 for (i = 0; i < hp->ns; i++)
634     for (j = 0; j < hp->ns; j += !i|(i==hp->ns-1) ? 1 : hp->ns-1) {
635     AMBSAMP *ap = &ambsam(hp,i,j);
636 greg 2.50 if ((ap->d <= FTINY) | (ap->d >= max_d))
637     continue; /* too far or too near */
638 greg 2.47 VSUB(vec, ap->p, hp->rp->rop);
639 greg 2.61 d = DOT(vec, hp->rp->ron);
640     d = 1.0/sqrt(DOT(vec,vec) - d*d);
641     u = DOT(vec, uv[0]) * d;
642     v = DOT(vec, uv[1]) * d;
643 greg 2.49 if ((r0*r0*u*u + r1*r1*v*v) * ap->d*ap->d <= 1.0)
644     continue; /* occluder outside ellipse */
645     ang = atan2a(v, u); /* else set direction flags */
646 greg 2.50 for (a1 = ang-.5*ang_res; a1 <= ang+.5*ang_res; a1 += ang_step)
647     flgs |= 1L<<(int)(16/PI*(a1 + 2.*PI*(a1 < 0)));
648 greg 2.47 }
649 greg 2.58 /* add low-angle incident (< 20deg) */
650     if (fabs(hp->rp->rod) <= 0.342) {
651     u = -DOT(hp->rp->rdir, uv[0]);
652     v = -DOT(hp->rp->rdir, uv[1]);
653     if ((r0*r0*u*u + r1*r1*v*v) > hp->rp->rot*hp->rp->rot) {
654     ang = atan2a(v, u);
655     ang += 2.*PI*(ang < 0);
656     ang *= 16/PI;
657     if ((ang < .5) | (ang >= 31.5))
658     flgs |= 0x80000001;
659     else
660     flgs |= 3L<<(int)(ang-.5);
661     }
662     }
663 greg 2.49 return(flgs);
664 greg 2.47 }
665    
666    
667 greg 2.26 int
668     doambient( /* compute ambient component */
669     COLOR rcol, /* input/output color */
670     RAY *r,
671     double wt,
672 greg 2.27 FVECT uv[2], /* returned (optional) */
673     float ra[2], /* returned (optional) */
674     float pg[2], /* returned (optional) */
675 greg 2.49 float dg[2], /* returned (optional) */
676     uint32 *crlp /* returned (optional) */
677 greg 2.26 )
678     {
679 greg 2.61 AMBHEMI *hp = samp_hemi(rcol, r, wt);
680 greg 2.41 FVECT my_uv[2];
681 greg 2.61 double d, K;
682 greg 2.41 AMBSAMP *ap;
683 greg 2.61 int i;
684     /* clear return values */
685 greg 2.26 if (uv != NULL)
686     memset(uv, 0, sizeof(FVECT)*2);
687     if (ra != NULL)
688     ra[0] = ra[1] = 0.0;
689     if (pg != NULL)
690     pg[0] = pg[1] = 0.0;
691     if (dg != NULL)
692     dg[0] = dg[1] = 0.0;
693 greg 2.49 if (crlp != NULL)
694     *crlp = 0;
695 greg 2.61 if (hp == NULL) /* sampling falure? */
696     return(0);
697    
698     if ((ra == NULL) & (pg == NULL) & (dg == NULL) ||
699     (hp->sampOK < 0) | (hp->ns < 4)) {
700     free(hp); /* Hessian not requested/possible */
701     return(-1); /* value-only return value */
702 greg 2.26 }
703 greg 2.61 if ((d = bright(rcol)) > FTINY) { /* normalize Y values */
704 greg 2.45 d = 0.99*(hp->ns*hp->ns)/d;
705 greg 2.38 K = 0.01;
706 greg 2.45 } else { /* or fall back on geometric Hessian */
707 greg 2.38 K = 1.0;
708     pg = NULL;
709     dg = NULL;
710 greg 2.53 crlp = NULL;
711 greg 2.38 }
712 greg 2.29 ap = hp->sa; /* relative Y channel from here on... */
713 greg 2.26 for (i = hp->ns*hp->ns; i--; ap++)
714 greg 2.38 colval(ap->v,CIEY) = bright(ap->v)*d + K;
715 greg 2.26
716     if (uv == NULL) /* make sure we have axis pointers */
717     uv = my_uv;
718     /* compute radii & pos. gradient */
719     ambHessian(hp, uv, ra, pg);
720 greg 2.29
721 greg 2.26 if (dg != NULL) /* compute direction gradient */
722     ambdirgrad(hp, uv, dg);
723 greg 2.29
724 greg 2.28 if (ra != NULL) { /* scale/clamp radii */
725 greg 2.35 if (pg != NULL) {
726     if (ra[0]*(d = fabs(pg[0])) > 1.0)
727     ra[0] = 1.0/d;
728     if (ra[1]*(d = fabs(pg[1])) > 1.0)
729     ra[1] = 1.0/d;
730 greg 2.48 if (ra[0] > ra[1])
731     ra[0] = ra[1];
732 greg 2.35 }
733 greg 2.29 if (ra[0] < minarad) {
734     ra[0] = minarad;
735     if (ra[1] < minarad)
736     ra[1] = minarad;
737     }
738 greg 2.60 ra[0] *= d = 1.0/sqrt(wt);
739 greg 2.26 if ((ra[1] *= d) > 2.0*ra[0])
740     ra[1] = 2.0*ra[0];
741 greg 2.28 if (ra[1] > maxarad) {
742     ra[1] = maxarad;
743     if (ra[0] > maxarad)
744     ra[0] = maxarad;
745     }
746 greg 2.53 /* flag encroached directions */
747 greg 2.57 if ((wt >= 0.89*AVGREFL) & (crlp != NULL))
748 greg 2.49 *crlp = ambcorral(hp, uv, ra[0]*ambacc, ra[1]*ambacc);
749 greg 2.35 if (pg != NULL) { /* cap gradient if necessary */
750     d = pg[0]*pg[0]*ra[0]*ra[0] + pg[1]*pg[1]*ra[1]*ra[1];
751     if (d > 1.0) {
752     d = 1.0/sqrt(d);
753     pg[0] *= d;
754     pg[1] *= d;
755     }
756     }
757 greg 2.26 }
758     free(hp); /* clean up and return */
759     return(1);
760     }
761    
762    
763 greg 2.25 #else /* ! NEWAMB */
764 greg 1.1
765    
766 greg 2.15 void
767 greg 2.14 inithemi( /* initialize sampling hemisphere */
768 greg 2.23 AMBHEMI *hp,
769 greg 2.16 COLOR ac,
770 greg 2.14 RAY *r,
771     double wt
772     )
773 greg 1.1 {
774 greg 2.16 double d;
775 greg 2.23 int i;
776 greg 2.14 /* set number of divisions */
777 greg 2.16 if (ambacc <= FTINY &&
778 greg 2.20 wt > (d = 0.8*intens(ac)*r->rweight/(ambdiv*minweight)))
779 greg 2.16 wt = d; /* avoid ray termination */
780     hp->nt = sqrt(ambdiv * wt / PI) + 0.5;
781 greg 2.14 i = ambacc > FTINY ? 3 : 1; /* minimum number of samples */
782     if (hp->nt < i)
783     hp->nt = i;
784     hp->np = PI * hp->nt + 0.5;
785     /* set number of super-samples */
786 greg 2.15 hp->ns = ambssamp * wt + 0.5;
787 greg 2.16 /* assign coefficient */
788 greg 2.14 copycolor(hp->acoef, ac);
789 greg 2.16 d = 1.0/(hp->nt*hp->np);
790     scalecolor(hp->acoef, d);
791 greg 2.14 /* make axes */
792     VCOPY(hp->uz, r->ron);
793     hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
794     for (i = 0; i < 3; i++)
795     if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6)
796     break;
797     if (i >= 3)
798     error(CONSISTENCY, "bad ray direction in inithemi");
799     hp->uy[i] = 1.0;
800     fcross(hp->ux, hp->uy, hp->uz);
801     normalize(hp->ux);
802     fcross(hp->uy, hp->uz, hp->ux);
803 greg 1.1 }
804    
805    
806 greg 2.9 int
807 greg 2.14 divsample( /* sample a division */
808 greg 2.23 AMBSAMP *dp,
809 greg 2.14 AMBHEMI *h,
810     RAY *r
811     )
812 greg 1.1 {
813     RAY ar;
814 greg 1.11 int hlist[3];
815     double spt[2];
816 greg 1.1 double xd, yd, zd;
817     double b2;
818     double phi;
819 greg 2.23 int i;
820 greg 2.15 /* ambient coefficient for weight */
821 greg 2.16 if (ambacc > FTINY)
822     setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
823     else
824     copycolor(ar.rcoef, h->acoef);
825 greg 2.14 if (rayorigin(&ar, AMBIENT, r, ar.rcoef) < 0)
826 greg 1.4 return(-1);
827 greg 2.17 if (ambacc > FTINY) {
828     multcolor(ar.rcoef, h->acoef);
829     scalecolor(ar.rcoef, 1./AVGREFL);
830     }
831 greg 1.1 hlist[0] = r->rno;
832     hlist[1] = dp->t;
833     hlist[2] = dp->p;
834 greg 1.13 multisamp(spt, 2, urand(ilhash(hlist,3)+dp->n));
835 greg 1.11 zd = sqrt((dp->t + spt[0])/h->nt);
836     phi = 2.0*PI * (dp->p + spt[1])/h->np;
837 gwlarson 2.8 xd = tcos(phi) * zd;
838     yd = tsin(phi) * zd;
839 greg 1.1 zd = sqrt(1.0 - zd*zd);
840 greg 1.2 for (i = 0; i < 3; i++)
841     ar.rdir[i] = xd*h->ux[i] +
842     yd*h->uy[i] +
843     zd*h->uz[i];
844 greg 2.22 checknorm(ar.rdir);
845 greg 1.2 dimlist[ndims++] = dp->t*h->np + dp->p + 90171;
846 greg 1.1 rayvalue(&ar);
847     ndims--;
848 greg 2.16 multcolor(ar.rcol, ar.rcoef); /* apply coefficient */
849 greg 1.1 addcolor(dp->v, ar.rcol);
850 greg 2.9 /* use rt to improve gradient calc */
851     if (ar.rt > FTINY && ar.rt < FHUGE)
852     dp->r += 1.0/ar.rt;
853 greg 1.1 /* (re)initialize error */
854     if (dp->n++) {
855     b2 = bright(dp->v)/dp->n - bright(ar.rcol);
856     b2 = b2*b2 + dp->k*((dp->n-1)*(dp->n-1));
857     dp->k = b2/(dp->n*dp->n);
858     } else
859     dp->k = 0.0;
860 greg 1.4 return(0);
861 greg 1.1 }
862    
863    
864 greg 2.14 static int
865     ambcmp( /* decreasing order */
866     const void *p1,
867     const void *p2
868     )
869     {
870     const AMBSAMP *d1 = (const AMBSAMP *)p1;
871     const AMBSAMP *d2 = (const AMBSAMP *)p2;
872    
873     if (d1->k < d2->k)
874     return(1);
875     if (d1->k > d2->k)
876     return(-1);
877     return(0);
878     }
879    
880    
881     static int
882     ambnorm( /* standard order */
883     const void *p1,
884     const void *p2
885     )
886     {
887     const AMBSAMP *d1 = (const AMBSAMP *)p1;
888     const AMBSAMP *d2 = (const AMBSAMP *)p2;
889 greg 2.23 int c;
890 greg 2.14
891     if ( (c = d1->t - d2->t) )
892     return(c);
893     return(d1->p - d2->p);
894     }
895    
896    
897 greg 1.1 double
898 greg 2.14 doambient( /* compute ambient component */
899 greg 2.23 COLOR rcol,
900 greg 2.14 RAY *r,
901     double wt,
902     FVECT pg,
903     FVECT dg
904     )
905 greg 1.1 {
906 greg 2.24 double b, d=0;
907 greg 1.1 AMBHEMI hemi;
908     AMBSAMP *div;
909     AMBSAMP dnew;
910 greg 2.23 double acol[3];
911     AMBSAMP *dp;
912 greg 1.1 double arad;
913 greg 2.19 int divcnt;
914 greg 2.23 int i, j;
915 greg 1.1 /* initialize hemisphere */
916 greg 2.23 inithemi(&hemi, rcol, r, wt);
917 greg 2.19 divcnt = hemi.nt * hemi.np;
918 greg 2.17 /* initialize */
919     if (pg != NULL)
920     pg[0] = pg[1] = pg[2] = 0.0;
921     if (dg != NULL)
922     dg[0] = dg[1] = dg[2] = 0.0;
923 greg 2.23 setcolor(rcol, 0.0, 0.0, 0.0);
924 greg 2.19 if (divcnt == 0)
925 greg 1.1 return(0.0);
926 greg 2.14 /* allocate super-samples */
927 greg 2.15 if (hemi.ns > 0 || pg != NULL || dg != NULL) {
928 greg 2.19 div = (AMBSAMP *)malloc(divcnt*sizeof(AMBSAMP));
929 greg 1.1 if (div == NULL)
930     error(SYSTEM, "out of memory in doambient");
931     } else
932     div = NULL;
933     /* sample the divisions */
934     arad = 0.0;
935 greg 2.23 acol[0] = acol[1] = acol[2] = 0.0;
936 greg 1.1 if ((dp = div) == NULL)
937     dp = &dnew;
938 greg 2.19 divcnt = 0;
939 greg 1.1 for (i = 0; i < hemi.nt; i++)
940     for (j = 0; j < hemi.np; j++) {
941     dp->t = i; dp->p = j;
942     setcolor(dp->v, 0.0, 0.0, 0.0);
943 greg 1.2 dp->r = 0.0;
944 greg 1.1 dp->n = 0;
945 greg 2.16 if (divsample(dp, &hemi, r) < 0) {
946 greg 2.19 if (div != NULL)
947     dp++;
948 greg 2.16 continue;
949     }
950 greg 2.6 arad += dp->r;
951 greg 2.19 divcnt++;
952 greg 1.1 if (div != NULL)
953     dp++;
954 greg 2.6 else
955 greg 1.1 addcolor(acol, dp->v);
956     }
957 greg 2.21 if (!divcnt) {
958     if (div != NULL)
959     free((void *)div);
960 greg 2.19 return(0.0); /* no samples taken */
961 greg 2.21 }
962 greg 2.19 if (divcnt < hemi.nt*hemi.np) {
963     pg = dg = NULL; /* incomplete sampling */
964     hemi.ns = 0;
965     } else if (arad > FTINY && divcnt/arad < minarad) {
966 greg 2.15 hemi.ns = 0; /* close enough */
967 greg 2.19 } else if (hemi.ns > 0) { /* else perform super-sampling? */
968 greg 1.4 comperrs(div, &hemi); /* compute errors */
969 greg 2.19 qsort(div, divcnt, sizeof(AMBSAMP), ambcmp); /* sort divs */
970 greg 1.1 /* super-sample */
971 greg 2.15 for (i = hemi.ns; i > 0; i--) {
972 schorsch 2.11 dnew = *div;
973 greg 2.16 if (divsample(&dnew, &hemi, r) < 0) {
974     dp++;
975     continue;
976     }
977     dp = div; /* reinsert */
978 greg 2.19 j = divcnt < i ? divcnt : i;
979 greg 1.1 while (--j > 0 && dnew.k < dp[1].k) {
980 schorsch 2.11 *dp = *(dp+1);
981 greg 1.1 dp++;
982     }
983 schorsch 2.11 *dp = dnew;
984 greg 1.1 }
985 greg 1.2 if (pg != NULL || dg != NULL) /* restore order */
986 greg 2.19 qsort(div, divcnt, sizeof(AMBSAMP), ambnorm);
987 greg 1.1 }
988     /* compute returned values */
989 greg 1.3 if (div != NULL) {
990 greg 2.19 arad = 0.0; /* note: divcnt may be < nt*np */
991     for (i = hemi.nt*hemi.np, dp = div; i-- > 0; dp++) {
992 greg 1.3 arad += dp->r;
993     if (dp->n > 1) {
994     b = 1.0/dp->n;
995     scalecolor(dp->v, b);
996     dp->r *= b;
997     dp->n = 1;
998     }
999     addcolor(acol, dp->v);
1000     }
1001 greg 1.5 b = bright(acol);
1002 greg 1.6 if (b > FTINY) {
1003 greg 2.17 b = 1.0/b; /* compute & normalize gradient(s) */
1004 greg 1.6 if (pg != NULL) {
1005     posgradient(pg, div, &hemi);
1006     for (i = 0; i < 3; i++)
1007     pg[i] *= b;
1008     }
1009     if (dg != NULL) {
1010     dirgradient(dg, div, &hemi);
1011     for (i = 0; i < 3; i++)
1012     dg[i] *= b;
1013     }
1014 greg 1.5 }
1015 greg 2.9 free((void *)div);
1016 greg 1.3 }
1017 greg 2.23 copycolor(rcol, acol);
1018 greg 1.1 if (arad <= FTINY)
1019 greg 1.16 arad = maxarad;
1020 greg 2.3 else
1021 greg 2.19 arad = (divcnt+hemi.ns)/arad;
1022 greg 1.15 if (pg != NULL) { /* reduce radius if gradient large */
1023     d = DOT(pg,pg);
1024     if (d*arad*arad > 1.0)
1025     arad = 1.0/sqrt(d);
1026     }
1027 greg 1.16 if (arad < minarad) {
1028 greg 1.1 arad = minarad;
1029 greg 1.16 if (pg != NULL && d*arad*arad > 1.0) { /* cap gradient */
1030     d = 1.0/arad/sqrt(d);
1031     for (i = 0; i < 3; i++)
1032     pg[i] *= d;
1033     }
1034     }
1035 greg 2.3 if ((arad /= sqrt(wt)) > maxarad)
1036     arad = maxarad;
1037     return(arad);
1038 greg 1.1 }
1039    
1040    
1041 greg 2.9 void
1042 greg 2.14 comperrs( /* compute initial error estimates */
1043     AMBSAMP *da, /* assumes standard ordering */
1044 greg 2.23 AMBHEMI *hp
1045 greg 2.14 )
1046 greg 1.1 {
1047     double b, b2;
1048     int i, j;
1049 greg 2.23 AMBSAMP *dp;
1050 greg 1.1 /* sum differences from neighbors */
1051     dp = da;
1052     for (i = 0; i < hp->nt; i++)
1053     for (j = 0; j < hp->np; j++) {
1054 greg 1.6 #ifdef DEBUG
1055     if (dp->t != i || dp->p != j)
1056     error(CONSISTENCY,
1057     "division order in comperrs");
1058     #endif
1059 greg 1.1 b = bright(dp[0].v);
1060     if (i > 0) { /* from above */
1061     b2 = bright(dp[-hp->np].v) - b;
1062     b2 *= b2 * 0.25;
1063     dp[0].k += b2;
1064     dp[-hp->np].k += b2;
1065     }
1066     if (j > 0) { /* from behind */
1067     b2 = bright(dp[-1].v) - b;
1068     b2 *= b2 * 0.25;
1069     dp[0].k += b2;
1070     dp[-1].k += b2;
1071 greg 1.4 } else { /* around */
1072     b2 = bright(dp[hp->np-1].v) - b;
1073 greg 1.1 b2 *= b2 * 0.25;
1074     dp[0].k += b2;
1075 greg 1.4 dp[hp->np-1].k += b2;
1076 greg 1.1 }
1077     dp++;
1078     }
1079     /* divide by number of neighbors */
1080     dp = da;
1081     for (j = 0; j < hp->np; j++) /* top row */
1082     (dp++)->k *= 1.0/3.0;
1083     if (hp->nt < 2)
1084     return;
1085     for (i = 1; i < hp->nt-1; i++) /* central region */
1086     for (j = 0; j < hp->np; j++)
1087     (dp++)->k *= 0.25;
1088     for (j = 0; j < hp->np; j++) /* bottom row */
1089     (dp++)->k *= 1.0/3.0;
1090     }
1091    
1092    
1093 greg 2.9 void
1094 greg 2.14 posgradient( /* compute position gradient */
1095     FVECT gv,
1096     AMBSAMP *da, /* assumes standard ordering */
1097 greg 2.23 AMBHEMI *hp
1098 greg 2.14 )
1099 greg 1.1 {
1100 greg 2.23 int i, j;
1101 greg 2.2 double nextsine, lastsine, b, d;
1102 greg 1.2 double mag0, mag1;
1103     double phi, cosp, sinp, xd, yd;
1104 greg 2.23 AMBSAMP *dp;
1105 greg 1.2
1106     xd = yd = 0.0;
1107     for (j = 0; j < hp->np; j++) {
1108     dp = da + j;
1109     mag0 = mag1 = 0.0;
1110 greg 2.2 lastsine = 0.0;
1111 greg 1.2 for (i = 0; i < hp->nt; i++) {
1112     #ifdef DEBUG
1113     if (dp->t != i || dp->p != j)
1114     error(CONSISTENCY,
1115     "division order in posgradient");
1116     #endif
1117     b = bright(dp->v);
1118     if (i > 0) {
1119     d = dp[-hp->np].r;
1120     if (dp[0].r > d) d = dp[0].r;
1121 greg 2.2 /* sin(t)*cos(t)^2 */
1122     d *= lastsine * (1.0 - (double)i/hp->nt);
1123 greg 1.2 mag0 += d*(b - bright(dp[-hp->np].v));
1124     }
1125 greg 2.2 nextsine = sqrt((double)(i+1)/hp->nt);
1126 greg 1.2 if (j > 0) {
1127     d = dp[-1].r;
1128     if (dp[0].r > d) d = dp[0].r;
1129 greg 2.2 mag1 += d * (nextsine - lastsine) *
1130     (b - bright(dp[-1].v));
1131 greg 1.2 } else {
1132     d = dp[hp->np-1].r;
1133     if (dp[0].r > d) d = dp[0].r;
1134 greg 2.2 mag1 += d * (nextsine - lastsine) *
1135     (b - bright(dp[hp->np-1].v));
1136 greg 1.2 }
1137     dp += hp->np;
1138 greg 2.2 lastsine = nextsine;
1139 greg 1.2 }
1140 greg 2.2 mag0 *= 2.0*PI / hp->np;
1141 greg 1.2 phi = 2.0*PI * (double)j/hp->np;
1142 gwlarson 2.8 cosp = tcos(phi); sinp = tsin(phi);
1143 greg 1.2 xd += mag0*cosp - mag1*sinp;
1144     yd += mag0*sinp + mag1*cosp;
1145     }
1146     for (i = 0; i < 3; i++)
1147 greg 2.16 gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])*(hp->nt*hp->np)/PI;
1148 greg 1.1 }
1149    
1150    
1151 greg 2.9 void
1152 greg 2.14 dirgradient( /* compute direction gradient */
1153     FVECT gv,
1154     AMBSAMP *da, /* assumes standard ordering */
1155 greg 2.23 AMBHEMI *hp
1156 greg 2.14 )
1157 greg 1.1 {
1158 greg 2.23 int i, j;
1159 greg 1.2 double mag;
1160     double phi, xd, yd;
1161 greg 2.23 AMBSAMP *dp;
1162 greg 1.2
1163     xd = yd = 0.0;
1164     for (j = 0; j < hp->np; j++) {
1165     dp = da + j;
1166     mag = 0.0;
1167     for (i = 0; i < hp->nt; i++) {
1168     #ifdef DEBUG
1169     if (dp->t != i || dp->p != j)
1170     error(CONSISTENCY,
1171     "division order in dirgradient");
1172     #endif
1173 greg 2.2 /* tan(t) */
1174     mag += bright(dp->v)/sqrt(hp->nt/(i+.5) - 1.0);
1175 greg 1.2 dp += hp->np;
1176     }
1177     phi = 2.0*PI * (j+.5)/hp->np + PI/2.0;
1178 gwlarson 2.8 xd += mag * tcos(phi);
1179     yd += mag * tsin(phi);
1180 greg 1.2 }
1181     for (i = 0; i < 3; i++)
1182 greg 2.16 gv[i] = xd*hp->ux[i] + yd*hp->uy[i];
1183 greg 1.1 }
1184 greg 2.25
1185     #endif /* ! NEWAMB */