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root/radiance/ray/src/rt/ambcomp.c
Revision: 2.85
Committed: Tue May 14 17:39:10 2019 UTC (5 years ago) by greg
Content type: text/plain
Branch: MAIN
CVS Tags: rad5R3
Changes since 2.84: +1 -427 lines
Log Message: 
Stripped out code related to old (pre-Hessian) ambient calculation

File Contents

# User Rev Content
1 greg 1.1 #ifndef lint
2 greg 2.85 static const char RCSid[] = "$Id: ambcomp.c,v 2.84 2019/02/26 00:37:54 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 2.26 extern void SDsquare2disk(double ds[2], double seedx, double seedy);
25    
26     typedef struct {
27 greg 2.44 COLOR v; /* hemisphere sample value */
28 greg 2.83 float d; /* reciprocal distance */
29 greg 2.44 FVECT p; /* intersection point */
30     } AMBSAMP; /* sample value */
31    
32     typedef struct {
33 greg 2.26 RAY *rp; /* originating ray sample */
34     int ns; /* number of samples per axis */
35 greg 2.61 int sampOK; /* acquired full sample set? */
36 greg 2.26 COLOR acoef; /* division contribution coefficient */
37 greg 2.61 double acol[3]; /* accumulated color */
38     FVECT ux, uy; /* tangent axis unit vectors */
39 greg 2.44 AMBSAMP sa[1]; /* sample array (extends struct) */
40 greg 2.26 } AMBHEMI; /* ambient sample hemisphere */
41    
42 greg 2.56 #define AI(h,i,j) ((i)*(h)->ns + (j))
43     #define ambsam(h,i,j) (h)->sa[AI(h,i,j)]
44 greg 2.26
45 greg 2.27 typedef struct {
46 greg 2.35 FVECT r_i, r_i1, e_i, rcp, rI2_eJ2;
47     double I1, I2;
48 greg 2.27 } FFTRI; /* vectors and coefficients for Hessian calculation */
49    
50 greg 2.26
51 greg 2.61 static int
52 greg 2.73 ambcollision( /* proposed direciton collides? */
53     AMBHEMI *hp,
54     int i,
55     int j,
56     FVECT dv
57     )
58     {
59 greg 2.74 double cos_thresh;
60     int ii, jj;
61 greg 2.75 /* min. spacing = 1/4th division */
62     cos_thresh = (PI/4.)/(double)hp->ns;
63 greg 2.74 cos_thresh = 1. - .5*cos_thresh*cos_thresh;
64     /* check existing neighbors */
65 greg 2.73 for (ii = i-1; ii <= i+1; ii++) {
66     if (ii < 0) continue;
67     if (ii >= hp->ns) break;
68     for (jj = j-1; jj <= j+1; jj++) {
69     AMBSAMP *ap;
70     FVECT avec;
71     double dprod;
72     if (jj < 0) continue;
73     if (jj >= hp->ns) break;
74     if ((ii==i) & (jj==j)) continue;
75     ap = &ambsam(hp,ii,jj);
76 greg 2.74 if (ap->d <= .5/FHUGE)
77     continue; /* no one home */
78 greg 2.73 VSUB(avec, ap->p, hp->rp->rop);
79     dprod = DOT(avec, dv);
80     if (dprod >= cos_thresh*VLEN(avec))
81     return(1); /* collision */
82     }
83     }
84 greg 2.74 return(0); /* nothing to worry about */
85 greg 2.73 }
86    
87    
88     static int
89 greg 2.61 ambsample( /* initial ambient division sample */
90     AMBHEMI *hp,
91     int i,
92     int j,
93     int n
94 greg 2.26 )
95     {
96 greg 2.61 AMBSAMP *ap = &ambsam(hp,i,j);
97     RAY ar;
98 greg 2.41 int hlist[3], ii;
99     double spt[2], zd;
100 greg 2.61 /* generate hemispherical sample */
101 greg 2.26 /* ambient coefficient for weight */
102     if (ambacc > FTINY)
103 greg 2.61 setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
104 greg 2.26 else
105 greg 2.61 copycolor(ar.rcoef, hp->acoef);
106 greg 2.62 if (rayorigin(&ar, AMBIENT, hp->rp, ar.rcoef) < 0)
107 greg 2.41 return(0);
108 greg 2.26 if (ambacc > FTINY) {
109 greg 2.61 multcolor(ar.rcoef, hp->acoef);
110     scalecolor(ar.rcoef, 1./AVGREFL);
111 greg 2.41 }
112     hlist[0] = hp->rp->rno;
113 greg 2.46 hlist[1] = j;
114     hlist[2] = i;
115 greg 2.41 multisamp(spt, 2, urand(ilhash(hlist,3)+n));
116 greg 2.73 resample:
117 greg 2.46 SDsquare2disk(spt, (j+spt[1])/hp->ns, (i+spt[0])/hp->ns);
118 greg 2.26 zd = sqrt(1. - spt[0]*spt[0] - spt[1]*spt[1]);
119     for (ii = 3; ii--; )
120 greg 2.61 ar.rdir[ii] = spt[0]*hp->ux[ii] +
121 greg 2.26 spt[1]*hp->uy[ii] +
122     zd*hp->rp->ron[ii];
123 greg 2.61 checknorm(ar.rdir);
124 greg 2.73 /* avoid coincident samples */
125     if (!n && ambcollision(hp, i, j, ar.rdir)) {
126     spt[0] = frandom(); spt[1] = frandom();
127 greg 2.75 goto resample; /* reject this sample */
128 greg 2.73 }
129 greg 2.56 dimlist[ndims++] = AI(hp,i,j) + 90171;
130 greg 2.61 rayvalue(&ar); /* evaluate ray */
131     ndims--;
132 greg 2.83 zd = raydistance(&ar);
133     if (zd <= FTINY)
134 greg 2.61 return(0); /* should never happen */
135     multcolor(ar.rcol, ar.rcoef); /* apply coefficient */
136 greg 2.83 if (zd*ap->d < 1.0) /* new/closer distance? */
137     ap->d = 1.0/zd;
138 greg 2.61 if (!n) { /* record first vertex & value */
139 greg 2.83 if (zd > 10.0*thescene.cusize + 1000.)
140     zd = 10.0*thescene.cusize + 1000.;
141     VSUM(ap->p, ar.rorg, ar.rdir, zd);
142 greg 2.61 copycolor(ap->v, ar.rcol);
143     } else { /* else update recorded value */
144     hp->acol[RED] -= colval(ap->v,RED);
145     hp->acol[GRN] -= colval(ap->v,GRN);
146     hp->acol[BLU] -= colval(ap->v,BLU);
147     zd = 1.0/(double)(n+1);
148     scalecolor(ar.rcol, zd);
149     zd *= (double)n;
150     scalecolor(ap->v, zd);
151     addcolor(ap->v, ar.rcol);
152     }
153     addcolor(hp->acol, ap->v); /* add to our sum */
154 greg 2.41 return(1);
155     }
156    
157    
158 greg 2.82 /* Estimate variance based on ambient division differences */
159 greg 2.41 static float *
160     getambdiffs(AMBHEMI *hp)
161     {
162 greg 2.77 const double normf = 1./bright(hp->acoef);
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 2.81 double b, b1, d2;
167 greg 2.41 int i, j;
168    
169     if (earr == NULL) /* out of memory? */
170     return(NULL);
171 greg 2.81 /* sum 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 2.81 b1 = bright(ap[-hp->ns].v);
177 greg 2.82 d2 = b - b1;
178     d2 *= d2*normf/(b + b1);
179 greg 2.41 ep[0] += d2;
180     ep[-hp->ns] += d2;
181     }
182 greg 2.55 if (!j) continue;
183     /* from behind */
184 greg 2.81 b1 = bright(ap[-1].v);
185 greg 2.82 d2 = b - b1;
186     d2 *= d2*normf/(b + b1);
187 greg 2.55 ep[0] += d2;
188     ep[-1] += d2;
189     if (!i) continue;
190     /* diagonal */
191 greg 2.81 b1 = bright(ap[-hp->ns-1].v);
192 greg 2.82 d2 = b - b1;
193     d2 *= d2*normf/(b + b1);
194 greg 2.55 ep[0] += d2;
195     ep[-hp->ns-1] += d2;
196 greg 2.41 }
197     /* correct for number of neighbors */
198 greg 2.55 earr[0] *= 8./3.;
199     earr[hp->ns-1] *= 8./3.;
200     earr[(hp->ns-1)*hp->ns] *= 8./3.;
201     earr[(hp->ns-1)*hp->ns + hp->ns-1] *= 8./3.;
202 greg 2.41 for (i = 1; i < hp->ns-1; i++) {
203 greg 2.55 earr[i*hp->ns] *= 8./5.;
204     earr[i*hp->ns + hp->ns-1] *= 8./5.;
205 greg 2.41 }
206     for (j = 1; j < hp->ns-1; j++) {
207 greg 2.55 earr[j] *= 8./5.;
208     earr[(hp->ns-1)*hp->ns + j] *= 8./5.;
209 greg 2.41 }
210     return(earr);
211     }
212    
213    
214 greg 2.43 /* Perform super-sampling on hemisphere (introduces bias) */
215 greg 2.41 static void
216 greg 2.61 ambsupersamp(AMBHEMI *hp, int cnt)
217 greg 2.41 {
218     float *earr = getambdiffs(hp);
219 greg 2.54 double e2rem = 0;
220 greg 2.41 float *ep;
221 greg 2.55 int i, j, n, nss;
222 greg 2.41
223     if (earr == NULL) /* just skip calc. if no memory */
224     return;
225 greg 2.54 /* accumulate estimated variances */
226 greg 2.55 for (ep = earr + hp->ns*hp->ns; ep > earr; )
227     e2rem += *--ep;
228 greg 2.41 ep = earr; /* perform super-sampling */
229 greg 2.81 for (i = 0; i < hp->ns; i++)
230     for (j = 0; j < hp->ns; j++) {
231 greg 2.55 if (e2rem <= FTINY)
232     goto done; /* nothing left to do */
233     nss = *ep/e2rem*cnt + frandom();
234 greg 2.62 for (n = 1; n <= nss && ambsample(hp,i,j,n); n++)
235 greg 2.77 if (!--cnt) goto done;
236 greg 2.61 e2rem -= *ep++; /* update remainder */
237 greg 2.41 }
238 greg 2.55 done:
239 greg 2.41 free(earr);
240     }
241    
242    
243 greg 2.61 static AMBHEMI *
244     samp_hemi( /* sample indirect hemisphere */
245     COLOR rcol,
246     RAY *r,
247     double wt
248     )
249     {
250     AMBHEMI *hp;
251     double d;
252     int n, i, j;
253 greg 2.77 /* insignificance check */
254     if (bright(rcol) <= FTINY)
255     return(NULL);
256 greg 2.61 /* set number of divisions */
257     if (ambacc <= FTINY &&
258     wt > (d = 0.8*intens(rcol)*r->rweight/(ambdiv*minweight)))
259     wt = d; /* avoid ray termination */
260     n = sqrt(ambdiv * wt) + 0.5;
261 greg 2.68 i = 1 + 5*(ambacc > FTINY); /* minimum number of samples */
262 greg 2.61 if (n < i)
263     n = i;
264     /* allocate sampling array */
265     hp = (AMBHEMI *)malloc(sizeof(AMBHEMI) + sizeof(AMBSAMP)*(n*n - 1));
266     if (hp == NULL)
267     error(SYSTEM, "out of memory in samp_hemi");
268     hp->rp = r;
269     hp->ns = n;
270     hp->acol[RED] = hp->acol[GRN] = hp->acol[BLU] = 0.0;
271 greg 2.62 memset(hp->sa, 0, sizeof(AMBSAMP)*n*n);
272 greg 2.61 hp->sampOK = 0;
273     /* assign coefficient */
274     copycolor(hp->acoef, rcol);
275     d = 1.0/(n*n);
276     scalecolor(hp->acoef, d);
277     /* make tangent plane axes */
278 greg 2.70 if (!getperpendicular(hp->ux, r->ron, 1))
279 greg 2.61 error(CONSISTENCY, "bad ray direction in samp_hemi");
280     VCROSS(hp->uy, r->ron, hp->ux);
281     /* sample divisions */
282     for (i = hp->ns; i--; )
283     for (j = hp->ns; j--; )
284     hp->sampOK += ambsample(hp, i, j, 0);
285     copycolor(rcol, hp->acol);
286     if (!hp->sampOK) { /* utter failure? */
287     free(hp);
288     return(NULL);
289     }
290     if (hp->sampOK < hp->ns*hp->ns) {
291     hp->sampOK *= -1; /* soft failure */
292     return(hp);
293     }
294 greg 2.84 if (hp->sampOK < 64)
295     return(hp); /* insufficient for super-sampling */
296 greg 2.61 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 2.50 int i, j;
653 greg 2.52 /* don't bother for a few samples */
654 greg 2.72 if (hp->ns < 8)
655 greg 2.52 return(0);
656     /* check distances overhead */
657 greg 2.51 for (i = hp->ns*3/4; i-- > hp->ns>>2; )
658     for (j = hp->ns*3/4; j-- > hp->ns>>2; )
659     avg_d += ambsam(hp,i,j).d;
660     avg_d *= 4.0/(hp->ns*hp->ns);
661 greg 2.52 if (avg_d*r0 >= 1.0) /* ceiling too low for corral? */
662     return(0);
663     if (avg_d >= max_d) /* insurance */
664 greg 2.51 return(0);
665     /* else circle around perimeter */
666 greg 2.47 for (i = 0; i < hp->ns; i++)
667     for (j = 0; j < hp->ns; j += !i|(i==hp->ns-1) ? 1 : hp->ns-1) {
668     AMBSAMP *ap = &ambsam(hp,i,j);
669 greg 2.50 if ((ap->d <= FTINY) | (ap->d >= max_d))
670     continue; /* too far or too near */
671 greg 2.47 VSUB(vec, ap->p, hp->rp->rop);
672 greg 2.62 u = DOT(vec, uv[0]);
673     v = DOT(vec, uv[1]);
674     if ((r0*r0*u*u + r1*r1*v*v) * ap->d*ap->d <= u*u + v*v)
675 greg 2.49 continue; /* occluder outside ellipse */
676     ang = atan2a(v, u); /* else set direction flags */
677 greg 2.66 for (a1 = ang-ang_res; a1 <= ang+ang_res; a1 += ang_step)
678 greg 2.50 flgs |= 1L<<(int)(16/PI*(a1 + 2.*PI*(a1 < 0)));
679 greg 2.47 }
680 greg 2.49 return(flgs);
681 greg 2.47 }
682    
683    
684 greg 2.26 int
685     doambient( /* compute ambient component */
686     COLOR rcol, /* input/output color */
687     RAY *r,
688     double wt,
689 greg 2.27 FVECT uv[2], /* returned (optional) */
690     float ra[2], /* returned (optional) */
691     float pg[2], /* returned (optional) */
692 greg 2.49 float dg[2], /* returned (optional) */
693     uint32 *crlp /* returned (optional) */
694 greg 2.26 )
695     {
696 greg 2.61 AMBHEMI *hp = samp_hemi(rcol, r, wt);
697 greg 2.41 FVECT my_uv[2];
698 greg 2.61 double d, K;
699 greg 2.41 AMBSAMP *ap;
700 greg 2.61 int i;
701     /* clear return values */
702 greg 2.26 if (uv != NULL)
703     memset(uv, 0, sizeof(FVECT)*2);
704     if (ra != NULL)
705     ra[0] = ra[1] = 0.0;
706     if (pg != NULL)
707     pg[0] = pg[1] = 0.0;
708     if (dg != NULL)
709     dg[0] = dg[1] = 0.0;
710 greg 2.49 if (crlp != NULL)
711     *crlp = 0;
712 greg 2.61 if (hp == NULL) /* sampling falure? */
713     return(0);
714    
715     if ((ra == NULL) & (pg == NULL) & (dg == NULL) ||
716 greg 2.68 (hp->sampOK < 0) | (hp->ns < 6)) {
717 greg 2.61 free(hp); /* Hessian not requested/possible */
718     return(-1); /* value-only return value */
719 greg 2.26 }
720 greg 2.61 if ((d = bright(rcol)) > FTINY) { /* normalize Y values */
721 greg 2.45 d = 0.99*(hp->ns*hp->ns)/d;
722 greg 2.38 K = 0.01;
723 greg 2.45 } else { /* or fall back on geometric Hessian */
724 greg 2.38 K = 1.0;
725     pg = NULL;
726     dg = NULL;
727 greg 2.53 crlp = NULL;
728 greg 2.38 }
729 greg 2.29 ap = hp->sa; /* relative Y channel from here on... */
730 greg 2.26 for (i = hp->ns*hp->ns; i--; ap++)
731 greg 2.38 colval(ap->v,CIEY) = bright(ap->v)*d + K;
732 greg 2.26
733     if (uv == NULL) /* make sure we have axis pointers */
734     uv = my_uv;
735     /* compute radii & pos. gradient */
736     ambHessian(hp, uv, ra, pg);
737 greg 2.29
738 greg 2.26 if (dg != NULL) /* compute direction gradient */
739     ambdirgrad(hp, uv, dg);
740 greg 2.29
741 greg 2.28 if (ra != NULL) { /* scale/clamp radii */
742 greg 2.35 if (pg != NULL) {
743     if (ra[0]*(d = fabs(pg[0])) > 1.0)
744     ra[0] = 1.0/d;
745     if (ra[1]*(d = fabs(pg[1])) > 1.0)
746     ra[1] = 1.0/d;
747 greg 2.48 if (ra[0] > ra[1])
748     ra[0] = ra[1];
749 greg 2.35 }
750 greg 2.29 if (ra[0] < minarad) {
751     ra[0] = minarad;
752     if (ra[1] < minarad)
753     ra[1] = minarad;
754     }
755 greg 2.60 ra[0] *= d = 1.0/sqrt(wt);
756 greg 2.26 if ((ra[1] *= d) > 2.0*ra[0])
757     ra[1] = 2.0*ra[0];
758 greg 2.28 if (ra[1] > maxarad) {
759     ra[1] = maxarad;
760     if (ra[0] > maxarad)
761     ra[0] = maxarad;
762     }
763 greg 2.53 /* flag encroached directions */
764 greg 2.71 if (crlp != NULL)
765 greg 2.49 *crlp = ambcorral(hp, uv, ra[0]*ambacc, ra[1]*ambacc);
766 greg 2.35 if (pg != NULL) { /* cap gradient if necessary */
767     d = pg[0]*pg[0]*ra[0]*ra[0] + pg[1]*pg[1]*ra[1]*ra[1];
768     if (d > 1.0) {
769     d = 1.0/sqrt(d);
770     pg[0] *= d;
771     pg[1] *= d;
772     }
773     }
774 greg 2.26 }
775     free(hp); /* clean up and return */
776     return(1);
777     }
778