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root/radiance/ray/src/rt/ambcomp.c
Revision: 2.27
Committed: Sat Apr 19 02:39:44 2014 UTC (10 years ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 2.26: +365 -23 lines
Log Message:
Compilable but untested version of Hessian calculation (-DNEWAMB)

File Contents

# User Rev Content
1 greg 1.1 #ifndef lint
2 greg 2.27 static const char RCSid[] = "$Id: ambcomp.c,v 2.26 2014/04/16 20:32:00 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 2.9 * Declarations of external symbols in ambient.h
12     */
13    
14 greg 2.10 #include "copyright.h"
15 greg 1.1
16     #include "ray.h"
17 greg 2.25 #include "ambient.h"
18     #include "random.h"
19 greg 1.1
20 greg 2.25 #ifdef NEWAMB
21 greg 1.1
22 greg 2.26 extern void SDsquare2disk(double ds[2], double seedx, double seedy);
23    
24     typedef struct {
25     RAY *rp; /* originating ray sample */
26 greg 2.27 FVECT ux, uy; /* tangent axis unit vectors */
27 greg 2.26 int ns; /* number of samples per axis */
28     COLOR acoef; /* division contribution coefficient */
29     struct s_ambsamp {
30     COLOR v; /* hemisphere sample value */
31     float p[3]; /* intersection point */
32     } sa[1]; /* sample array (extends struct) */
33     } AMBHEMI; /* ambient sample hemisphere */
34    
35     #define ambsamp(h,i,j) (h)->sa[(i)*(h)->ns + (j)]
36    
37 greg 2.27 typedef struct {
38     FVECT r_i, r_i1, e_i;
39     double nf, I1, I2, J2;
40     } FFTRI; /* vectors and coefficients for Hessian calculation */
41    
42 greg 2.26
43     static AMBHEMI *
44     inithemi( /* initialize sampling hemisphere */
45     COLOR ac,
46     RAY *r,
47     double wt
48     )
49     {
50     AMBHEMI *hp;
51     double d;
52     int n, i;
53     /* set number of divisions */
54     if (ambacc <= FTINY &&
55     wt > (d = 0.8*intens(ac)*r->rweight/(ambdiv*minweight)))
56     wt = d; /* avoid ray termination */
57     n = sqrt(ambdiv * wt) + 0.5;
58 greg 2.27 i = 1 + 5*(ambacc > FTINY); /* minimum number of samples */
59 greg 2.26 if (n < i)
60     n = i;
61     /* allocate sampling array */
62     hp = (AMBHEMI *)malloc(sizeof(AMBHEMI) +
63     sizeof(struct s_ambsamp)*(n*n - 1));
64     if (hp == NULL)
65     return(NULL);
66     hp->rp = r;
67     hp->ns = n;
68     /* assign coefficient */
69     copycolor(hp->acoef, ac);
70     d = 1.0/(n*n);
71     scalecolor(hp->acoef, d);
72     /* make tangent axes */
73     hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
74     for (i = 0; i < 3; i++)
75 greg 2.27 if (r->ron[i] < 0.6 && r->ron[i] > -0.6)
76 greg 2.26 break;
77     if (i >= 3)
78     error(CONSISTENCY, "bad ray direction in inithemi()");
79     hp->uy[i] = 1.0;
80 greg 2.27 VCROSS(hp->ux, hp->uy, r->ron);
81 greg 2.26 normalize(hp->ux);
82 greg 2.27 VCROSS(hp->uy, r->ron, hp->ux);
83 greg 2.26 /* we're ready to sample */
84     return(hp);
85     }
86    
87    
88     static int
89     ambsample( /* sample an ambient direction */
90     AMBHEMI *hp,
91     int i,
92 greg 2.27 int j
93 greg 2.26 )
94     {
95     struct s_ambsamp *ap = &ambsamp(hp,i,j);
96     RAY ar;
97     int hlist[3];
98 greg 2.27 double spt[2], zd;
99 greg 2.26 int ii;
100     /* ambient coefficient for weight */
101     if (ambacc > FTINY)
102     setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
103     else
104     copycolor(ar.rcoef, hp->acoef);
105     if (rayorigin(&ar, AMBIENT, hp->rp, ar.rcoef) < 0) {
106     setcolor(ap->v, 0., 0., 0.);
107 greg 2.27 VCOPY(ap->p, hp->rp->rop);
108 greg 2.26 return(0); /* no sample taken */
109     }
110     if (ambacc > FTINY) {
111     multcolor(ar.rcoef, hp->acoef);
112     scalecolor(ar.rcoef, 1./AVGREFL);
113     }
114     /* generate hemispherical sample */
115 greg 2.27 SDsquare2disk(spt, (i+.1+.8*frandom())/hp->ns,
116     (j+.1+.8*frandom())/hp->ns);
117 greg 2.26 zd = sqrt(1. - spt[0]*spt[0] - spt[1]*spt[1]);
118     for (ii = 3; ii--; )
119     ar.rdir[ii] = spt[0]*hp->ux[ii] +
120     spt[1]*hp->uy[ii] +
121     zd*hp->rp->ron[ii];
122     checknorm(ar.rdir);
123     dimlist[ndims++] = i*hp->ns + j + 90171;
124     rayvalue(&ar); /* evaluate ray */
125     ndims--;
126     multcolor(ar.rcol, ar.rcoef); /* apply coefficient */
127     copycolor(ap->v, ar.rcol);
128     if (ar.rt > 20.0*maxarad) /* limit vertex distance */
129     ar.rt = 20.0*maxarad;
130     VSUM(ap->p, ar.rorg, ar.rdir, ar.rt);
131     return(1);
132     }
133    
134    
135 greg 2.27 /* Compute vectors and coefficients for Hessian/gradient calcs */
136     static void
137     comp_fftri(FFTRI *ftp, float ap0[3], float ap1[3], FVECT rop)
138     {
139     FVECT v1;
140     double dot_e, dot_er, dot_r, dot_r1;
141    
142     VSUB(ftp->r_i, ap0, rop);
143     VSUB(ftp->r_i1, ap1, rop);
144     VSUB(ftp->e_i, ap1, ap0);
145     VCROSS(v1, ftp->e_i, ftp->r_i);
146     ftp->nf = 1.0/DOT(v1,v1);
147     VCROSS(v1, ftp->r_i, ftp->r_i1);
148     ftp->I1 = sqrt(DOT(v1,v1)*ftp->nf);
149     dot_e = DOT(ftp->e_i,ftp->e_i);
150     dot_er = DOT(ftp->e_i, ftp->r_i);
151     dot_r = DOT(ftp->r_i,ftp->r_i);
152     dot_r1 = DOT(ftp->r_i1,ftp->r_i1);
153     ftp->I2 = ( DOT(ftp->e_i, ftp->r_i1)/dot_r1 - dot_er/dot_r +
154     dot_e*ftp->I1 )*0.5*ftp->nf;
155     ftp->J2 = 0.25*ftp->nf*( 1.0/dot_r - 1.0/dot_r1 ) -
156     dot_er/dot_e*ftp->I2;
157     }
158    
159    
160     /* Compose matrix from two vectors */
161     static void
162     compose_matrix(FVECT mat[3], FVECT va, FVECT vb)
163     {
164     mat[0][0] = 2.0*va[0]*vb[0];
165     mat[1][1] = 2.0*va[1]*vb[1];
166     mat[2][2] = 2.0*va[2]*vb[2];
167     mat[0][1] = mat[1][0] = va[0]*vb[1] + va[1]*vb[0];
168     mat[0][2] = mat[2][0] = va[0]*vb[2] + va[2]*vb[0];
169     mat[1][2] = mat[2][1] = va[1]*vb[2] + va[2]*vb[1];
170     }
171    
172    
173     /* Compute partial 3x3 Hessian matrix for edge */
174     static void
175     comp_hessian(FVECT hess[3], FFTRI *ftp, FVECT nrm)
176     {
177     FVECT v1, v2;
178     FVECT m1[3], m2[3], m3[3], m4[3];
179     double d1, d2, d3, d4;
180     double I3, J3, K3;
181     int i, j;
182     /* compute intermediate coefficients */
183     d1 = 1.0/DOT(ftp->r_i,ftp->r_i);
184     d2 = 1.0/DOT(ftp->r_i1,ftp->r_i1);
185     d3 = 1.0/DOT(ftp->e_i,ftp->e_i);
186     d4 = DOT(ftp->e_i, ftp->r_i);
187     I3 = 0.25*ftp->nf*( DOT(ftp->e_i, ftp->r_i1)*d2*d2 - d4*d1*d1 +
188     3.0*ftp->I2*d3 );
189     J3 = 0.25*d3*(d1*d1 - d2*d2) - d4*d3*I3;
190     K3 = d3*(ftp->I2 - I3/d1 - 2.0*d4*J3);
191     /* intermediate matrices */
192     VCROSS(v1, nrm, ftp->e_i);
193     for (j = 3; j--; )
194     v2[i] = ftp->I2*ftp->r_i[j] + ftp->J2*ftp->e_i[j];
195     compose_matrix(m1, v1, v2);
196     compose_matrix(m2, ftp->r_i, ftp->r_i);
197     compose_matrix(m3, ftp->e_i, ftp->e_i);
198     compose_matrix(m4, ftp->r_i, ftp->e_i);
199     VCROSS(v1, ftp->r_i, ftp->e_i);
200     d1 = DOT(nrm, v1);
201     d2 = -d1*ftp->I2;
202     d1 *= 2.0;
203     for (i = 3; i--; ) /* final matrix sum */
204     for (j = 3; j--; ) {
205     hess[i][j] = m1[i][j] + d1*( I3*m2[i][j] + K3*m3[i][j] +
206     2.0*J3*m4[i][j] );
207     hess[i][j] += d2*(i==j);
208     hess[i][j] *= -1.0/PI;
209     }
210     }
211    
212    
213     /* Reverse hessian calculation result for edge in other direction */
214     static void
215     rev_hessian(FVECT hess[3])
216     {
217     int i;
218    
219     for (i = 3; i--; ) {
220     hess[i][0] = -hess[i][0];
221     hess[i][1] = -hess[i][1];
222     hess[i][2] = -hess[i][2];
223     }
224     }
225    
226    
227     /* Add to radiometric Hessian from the given triangle */
228     static void
229     add2hessian(FVECT hess[3], FVECT ehess1[3],
230     FVECT ehess2[3], FVECT ehess3[3], COLORV v)
231     {
232     int i, j;
233    
234     for (i = 3; i--; )
235     for (j = 3; j--; )
236     hess[i][j] += v*( ehess1[i][j] + ehess2[i][j] + ehess3[i][j] );
237     }
238    
239    
240     /* Compute partial displacement form factor gradient for edge */
241     static void
242     comp_gradient(FVECT grad, FFTRI *ftp, FVECT nrm)
243     {
244     FVECT vcp;
245     double f1;
246     int i;
247    
248     VCROSS(vcp, ftp->r_i, ftp->r_i1);
249     f1 = 2.0*DOT(nrm, vcp);
250     VCROSS(vcp, nrm, ftp->e_i);
251     for (i = 3; i--; )
252     grad[i] = (0.5/PI)*( ftp->I1*vcp[i] +
253     f1*(ftp->I2*ftp->r_i[i] + ftp->J2*ftp->e_i[i]) );
254     }
255    
256    
257     /* Reverse gradient calculation result for edge in other direction */
258     static void
259     rev_gradient(FVECT grad)
260     {
261     grad[0] = -grad[0];
262     grad[1] = -grad[1];
263     grad[2] = -grad[2];
264     }
265    
266    
267     /* Add to displacement gradient from the given triangle */
268     static void
269     add2gradient(FVECT grad, FVECT egrad1, FVECT egrad2, FVECT egrad3, COLORV v)
270     {
271     int i;
272    
273     for (i = 3; i--; )
274     grad[i] += v*( egrad1[i] + egrad2[i] + egrad3[i] );
275     }
276    
277    
278     /* Return brightness of furthest ambient sample */
279     static COLORV
280     back_ambval(struct s_ambsamp *ap1, struct s_ambsamp *ap2,
281     struct s_ambsamp *ap3, FVECT orig)
282     {
283     COLORV vback;
284     FVECT vec;
285     double d2, d2best;
286    
287     VSUB(vec, ap1->p, orig);
288     d2best = DOT(vec,vec);
289     vback = ap1->v[CIEY];
290     VSUB(vec, ap2->p, orig);
291     d2 = DOT(vec,vec);
292     if (d2 > d2best) {
293     d2best = d2;
294     vback = ap2->v[CIEY];
295     }
296     VSUB(vec, ap3->p, orig);
297     d2 = DOT(vec,vec);
298     if (d2 > d2best)
299     return(ap3->v[CIEY]);
300     return(vback);
301     }
302    
303    
304     /* Compute anisotropic radii and eigenvector directions */
305     static int
306     eigenvectors(FVECT uv[2], float ra[2], FVECT hessian[3])
307     {
308     double hess2[2][2];
309     FVECT a, b;
310     double evalue[2], slope1, xmag1;
311     int i;
312     /* project Hessian to sample plane */
313     for (i = 3; i--; ) {
314     a[i] = DOT(hessian[i], uv[0]);
315     b[i] = DOT(hessian[i], uv[1]);
316     }
317     hess2[0][0] = DOT(uv[0], a);
318     hess2[0][1] = DOT(uv[0], b);
319     hess2[1][0] = DOT(uv[1], a);
320     hess2[1][1] = DOT(uv[1], b);
321     /* compute eigenvalues */
322     if (quadratic(evalue, 1.0, -hess2[0][0]-hess2[1][1],
323     hess2[0][0]*hess2[1][1]-hess2[0][1]*hess2[1][0]) != 2 ||
324     (evalue[0] = fabs(evalue[0])) <= FTINY*FTINY*FTINY ||
325     (evalue[1] = fabs(evalue[1])) <= FTINY*FTINY*FTINY)
326     error(INTERNAL, "bad eigenvalue calculation");
327    
328     if (evalue[0] > evalue[1]) {
329     ra[0] = 1.0/sqrt(sqrt(evalue[0]));
330     ra[1] = 1.0/sqrt(sqrt(evalue[1]));
331     slope1 = evalue[1];
332     } else {
333     ra[0] = 1.0/sqrt(sqrt(evalue[1]));
334     ra[1] = 1.0/sqrt(sqrt(evalue[0]));
335     slope1 = evalue[0];
336     }
337     /* compute unit eigenvectors */
338     if (fabs(hess2[0][1]) <= FTINY)
339     return; /* uv OK as is */
340     slope1 = (slope1 - hess2[0][0]) / hess2[0][1];
341     xmag1 = sqrt(1.0/(1.0 + slope1*slope1));
342     for (i = 3; i--; ) {
343     b[i] = xmag1*uv[0][i] + slope1*xmag1*uv[1][i];
344     a[i] = slope1*xmag1*uv[0][i] - xmag1*uv[1][i];
345     }
346     VCOPY(uv[0], a);
347     VCOPY(uv[1], b);
348     }
349    
350    
351 greg 2.26 static void
352     ambHessian( /* anisotropic radii & pos. gradient */
353     AMBHEMI *hp,
354     FVECT uv[2], /* returned */
355     float ra[2], /* returned */
356     float pg[2] /* returned */
357     )
358     {
359 greg 2.27 static char memerrmsg[] = "out of memory in ambHessian()";
360     FVECT (*hessrow)[3] = NULL;
361     FVECT *gradrow = NULL;
362     FVECT hessian[3];
363     FVECT gradient;
364     FFTRI fftr;
365     int i, j;
366     /* be sure to assign unit vectors */
367     VCOPY(uv[0], hp->ux);
368     VCOPY(uv[1], hp->uy);
369     /* clock-wise vertex traversal from sample POV */
370     if (ra != NULL) { /* initialize Hessian row buffer */
371     hessrow = (FVECT (*)[3])malloc(sizeof(FVECT)*3*hp->ns);
372     if (hessrow == NULL)
373     error(SYSTEM, memerrmsg);
374     memset(hessian, 0, sizeof(hessian));
375     } else if (pg == NULL) /* bogus call? */
376     return;
377     if (pg != NULL) { /* initialize form factor row buffer */
378     gradrow = (FVECT *)malloc(sizeof(FVECT)*hp->ns);
379     if (gradrow == NULL)
380     error(SYSTEM, memerrmsg);
381     memset(gradient, 0, sizeof(gradient));
382     }
383     /* compute first row of edges */
384     for (j = 0; j < hp->ns-1; j++) {
385     comp_fftri(&fftr, ambsamp(hp,0,j).p,
386     ambsamp(hp,0,j+1).p, hp->rp->rop);
387     if (hessrow != NULL)
388     comp_hessian(hessrow[j], &fftr, hp->rp->ron);
389     if (gradrow != NULL)
390     comp_gradient(gradrow[j], &fftr, hp->rp->ron);
391     }
392     /* sum each row of triangles */
393     for (i = 0; i < hp->ns-1; i++) {
394     FVECT hesscol[3]; /* compute first vertical edge */
395     FVECT gradcol;
396     comp_fftri(&fftr, ambsamp(hp,i,0).p,
397     ambsamp(hp,i+1,0).p, hp->rp->rop);
398     if (hessrow != NULL)
399     comp_hessian(hesscol, &fftr, hp->rp->ron);
400     if (gradrow != NULL)
401     comp_gradient(gradcol, &fftr, hp->rp->ron);
402     for (j = 0; j < hp->ns-1; j++) {
403     FVECT hessdia[3]; /* compute triangle contributions */
404     FVECT graddia;
405     COLORV backg;
406     backg = back_ambval(&ambsamp(hp,i,j), &ambsamp(hp,i,j+1),
407     &ambsamp(hp,i+1,j), hp->rp->rop);
408     /* diagonal (inner) edge */
409     comp_fftri(&fftr, ambsamp(hp,i,j+1).p,
410     ambsamp(hp,i+1,j).p, hp->rp->rop);
411     if (hessrow != NULL) {
412     comp_hessian(hessdia, &fftr, hp->rp->ron);
413     rev_hessian(hesscol);
414     add2hessian(hessian, hessrow[j], hessdia, hesscol, backg);
415     }
416     if (gradient != NULL) {
417     comp_gradient(graddia, &fftr, hp->rp->ron);
418     rev_gradient(gradcol);
419     add2gradient(gradient, gradrow[j], graddia, gradcol, backg);
420     }
421     /* initialize edge in next row */
422     comp_fftri(&fftr, ambsamp(hp,i+1,j+1).p,
423     ambsamp(hp,i+1,j).p, hp->rp->rop);
424     if (hessrow != NULL)
425     comp_hessian(hessrow[j], &fftr, hp->rp->ron);
426     if (gradrow != NULL)
427     comp_gradient(gradrow[j], &fftr, hp->rp->ron);
428     /* new column edge & paired triangle */
429     backg = back_ambval(&ambsamp(hp,i,j+1), &ambsamp(hp,i+1,j+1),
430     &ambsamp(hp,i+1,j), hp->rp->rop);
431     comp_fftri(&fftr, ambsamp(hp,i,j+1).p, ambsamp(hp,i+1,j+1).p,
432     hp->rp->rop);
433     if (hessrow != NULL) {
434     comp_hessian(hesscol, &fftr, hp->rp->ron);
435     rev_hessian(hessdia);
436     add2hessian(hessian, hessrow[j], hessdia, hesscol, backg);
437     if (i < hp->ns-2)
438     rev_hessian(hessrow[j]);
439     }
440     if (gradrow != NULL) {
441     comp_gradient(gradcol, &fftr, hp->rp->ron);
442     rev_gradient(graddia);
443     add2gradient(gradient, gradrow[j], graddia, gradcol, backg);
444     if (i < hp->ns-2)
445     rev_gradient(gradrow[j]);
446     }
447     }
448     }
449     /* release row buffers */
450     if (hessrow != NULL) free(hessrow);
451     if (gradrow != NULL) free(gradrow);
452    
453     if (ra != NULL) /* extract eigenvectors & radii */
454     eigenvectors(uv, ra, hessian);
455     if (pg != NULL) { /* project position gradient */
456     pg[0] = DOT(gradient, uv[0]);
457     pg[1] = DOT(gradient, uv[1]);
458     }
459     }
460    
461    
462     /* Compute direction gradient from a hemispherical sampling */
463     static void
464     ambdirgrad(AMBHEMI *hp, FVECT uv[2], float dg[2])
465     {
466     struct s_ambsamp *ap;
467     int n;
468    
469     dg[0] = dg[1] = 0;
470     for (ap = hp->sa, n = hp->ns*hp->ns; n--; ap++) {
471     FVECT vd;
472     double gfact;
473     /* use vector for azimuth + 90deg */
474     VSUB(vd, ap->p, hp->rp->rop);
475     /* brightness with tangent factor */
476     gfact = ap->v[CIEY] / DOT(hp->rp->ron, vd);
477     /* sine = proj_radius/vd_length */
478     dg[0] -= DOT(uv[1], vd) * gfact ;
479     dg[1] += DOT(uv[0], vd) * gfact;
480 greg 2.26 }
481     }
482    
483 greg 2.27
484 greg 2.26 int
485     doambient( /* compute ambient component */
486     COLOR rcol, /* input/output color */
487     RAY *r,
488     double wt,
489 greg 2.27 FVECT uv[2], /* returned (optional) */
490     float ra[2], /* returned (optional) */
491     float pg[2], /* returned (optional) */
492     float dg[2] /* returned (optional) */
493 greg 2.26 )
494     {
495     int cnt = 0;
496     FVECT my_uv[2];
497     AMBHEMI *hp;
498     double d, acol[3];
499     struct s_ambsamp *ap;
500     int i, j;
501     /* initialize */
502     if ((hp = inithemi(rcol, r, wt)) == NULL)
503     return(0);
504     if (uv != NULL)
505     memset(uv, 0, sizeof(FVECT)*2);
506     if (ra != NULL)
507     ra[0] = ra[1] = 0.0;
508     if (pg != NULL)
509     pg[0] = pg[1] = 0.0;
510     if (dg != NULL)
511     dg[0] = dg[1] = 0.0;
512     /* sample the hemisphere */
513     acol[0] = acol[1] = acol[2] = 0.0;
514 greg 2.27 for (i = hp->ns; i--; )
515     for (j = hp->ns; j--; )
516 greg 2.26 if (ambsample(hp, i, j)) {
517     ap = &ambsamp(hp,i,j);
518     addcolor(acol, ap->v);
519     ++cnt;
520     }
521     if (!cnt) {
522     setcolor(rcol, 0.0, 0.0, 0.0);
523     free(hp);
524     return(0); /* no valid samples */
525     }
526     d = 1.0 / cnt; /* final indirect irradiance/PI */
527     acol[0] *= d; acol[1] *= d; acol[2] *= d;
528     copycolor(rcol, acol);
529     if (cnt < hp->ns*hp->ns || /* incomplete sampling? */
530     (ra == NULL) & (pg == NULL) & (dg == NULL)) {
531     free(hp);
532     return(-1); /* no radius or gradient calc. */
533     }
534     d = 0.01 * bright(rcol); /* add in 1% before Hessian comp. */
535     if (d < FTINY) d = FTINY;
536     ap = hp->sa; /* using Y channel from here on... */
537     for (i = hp->ns*hp->ns; i--; ap++)
538     colval(ap->v,CIEY) = bright(ap->v) + d;
539    
540     if (uv == NULL) /* make sure we have axis pointers */
541     uv = my_uv;
542     /* compute radii & pos. gradient */
543     ambHessian(hp, uv, ra, pg);
544     if (dg != NULL) /* compute direction gradient */
545     ambdirgrad(hp, uv, dg);
546     if (ra != NULL) { /* adjust/clamp radii */
547 greg 2.27 d = sqrt(sqrt((4.0/PI)*bright(rcol)/wt));
548 greg 2.26 if ((ra[0] *= d) > maxarad)
549     ra[0] = maxarad;
550     if ((ra[1] *= d) > 2.0*ra[0])
551     ra[1] = 2.0*ra[0];
552     }
553     free(hp); /* clean up and return */
554     return(1);
555     }
556    
557    
558 greg 2.25 #else /* ! NEWAMB */
559 greg 1.1
560    
561 greg 2.15 void
562 greg 2.14 inithemi( /* initialize sampling hemisphere */
563 greg 2.23 AMBHEMI *hp,
564 greg 2.16 COLOR ac,
565 greg 2.14 RAY *r,
566     double wt
567     )
568 greg 1.1 {
569 greg 2.16 double d;
570 greg 2.23 int i;
571 greg 2.14 /* set number of divisions */
572 greg 2.16 if (ambacc <= FTINY &&
573 greg 2.20 wt > (d = 0.8*intens(ac)*r->rweight/(ambdiv*minweight)))
574 greg 2.16 wt = d; /* avoid ray termination */
575     hp->nt = sqrt(ambdiv * wt / PI) + 0.5;
576 greg 2.14 i = ambacc > FTINY ? 3 : 1; /* minimum number of samples */
577     if (hp->nt < i)
578     hp->nt = i;
579     hp->np = PI * hp->nt + 0.5;
580     /* set number of super-samples */
581 greg 2.15 hp->ns = ambssamp * wt + 0.5;
582 greg 2.16 /* assign coefficient */
583 greg 2.14 copycolor(hp->acoef, ac);
584 greg 2.16 d = 1.0/(hp->nt*hp->np);
585     scalecolor(hp->acoef, d);
586 greg 2.14 /* make axes */
587     VCOPY(hp->uz, r->ron);
588     hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
589     for (i = 0; i < 3; i++)
590     if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6)
591     break;
592     if (i >= 3)
593     error(CONSISTENCY, "bad ray direction in inithemi");
594     hp->uy[i] = 1.0;
595     fcross(hp->ux, hp->uy, hp->uz);
596     normalize(hp->ux);
597     fcross(hp->uy, hp->uz, hp->ux);
598 greg 1.1 }
599    
600    
601 greg 2.9 int
602 greg 2.14 divsample( /* sample a division */
603 greg 2.23 AMBSAMP *dp,
604 greg 2.14 AMBHEMI *h,
605     RAY *r
606     )
607 greg 1.1 {
608     RAY ar;
609 greg 1.11 int hlist[3];
610     double spt[2];
611 greg 1.1 double xd, yd, zd;
612     double b2;
613     double phi;
614 greg 2.23 int i;
615 greg 2.15 /* ambient coefficient for weight */
616 greg 2.16 if (ambacc > FTINY)
617     setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
618     else
619     copycolor(ar.rcoef, h->acoef);
620 greg 2.14 if (rayorigin(&ar, AMBIENT, r, ar.rcoef) < 0)
621 greg 1.4 return(-1);
622 greg 2.17 if (ambacc > FTINY) {
623     multcolor(ar.rcoef, h->acoef);
624     scalecolor(ar.rcoef, 1./AVGREFL);
625     }
626 greg 1.1 hlist[0] = r->rno;
627     hlist[1] = dp->t;
628     hlist[2] = dp->p;
629 greg 1.13 multisamp(spt, 2, urand(ilhash(hlist,3)+dp->n));
630 greg 1.11 zd = sqrt((dp->t + spt[0])/h->nt);
631     phi = 2.0*PI * (dp->p + spt[1])/h->np;
632 gwlarson 2.8 xd = tcos(phi) * zd;
633     yd = tsin(phi) * zd;
634 greg 1.1 zd = sqrt(1.0 - zd*zd);
635 greg 1.2 for (i = 0; i < 3; i++)
636     ar.rdir[i] = xd*h->ux[i] +
637     yd*h->uy[i] +
638     zd*h->uz[i];
639 greg 2.22 checknorm(ar.rdir);
640 greg 1.2 dimlist[ndims++] = dp->t*h->np + dp->p + 90171;
641 greg 1.1 rayvalue(&ar);
642     ndims--;
643 greg 2.16 multcolor(ar.rcol, ar.rcoef); /* apply coefficient */
644 greg 1.1 addcolor(dp->v, ar.rcol);
645 greg 2.9 /* use rt to improve gradient calc */
646     if (ar.rt > FTINY && ar.rt < FHUGE)
647     dp->r += 1.0/ar.rt;
648 greg 1.1 /* (re)initialize error */
649     if (dp->n++) {
650     b2 = bright(dp->v)/dp->n - bright(ar.rcol);
651     b2 = b2*b2 + dp->k*((dp->n-1)*(dp->n-1));
652     dp->k = b2/(dp->n*dp->n);
653     } else
654     dp->k = 0.0;
655 greg 1.4 return(0);
656 greg 1.1 }
657    
658    
659 greg 2.14 static int
660     ambcmp( /* decreasing order */
661     const void *p1,
662     const void *p2
663     )
664     {
665     const AMBSAMP *d1 = (const AMBSAMP *)p1;
666     const AMBSAMP *d2 = (const AMBSAMP *)p2;
667    
668     if (d1->k < d2->k)
669     return(1);
670     if (d1->k > d2->k)
671     return(-1);
672     return(0);
673     }
674    
675    
676     static int
677     ambnorm( /* standard order */
678     const void *p1,
679     const void *p2
680     )
681     {
682     const AMBSAMP *d1 = (const AMBSAMP *)p1;
683     const AMBSAMP *d2 = (const AMBSAMP *)p2;
684 greg 2.23 int c;
685 greg 2.14
686     if ( (c = d1->t - d2->t) )
687     return(c);
688     return(d1->p - d2->p);
689     }
690    
691    
692 greg 1.1 double
693 greg 2.14 doambient( /* compute ambient component */
694 greg 2.23 COLOR rcol,
695 greg 2.14 RAY *r,
696     double wt,
697     FVECT pg,
698     FVECT dg
699     )
700 greg 1.1 {
701 greg 2.24 double b, d=0;
702 greg 1.1 AMBHEMI hemi;
703     AMBSAMP *div;
704     AMBSAMP dnew;
705 greg 2.23 double acol[3];
706     AMBSAMP *dp;
707 greg 1.1 double arad;
708 greg 2.19 int divcnt;
709 greg 2.23 int i, j;
710 greg 1.1 /* initialize hemisphere */
711 greg 2.23 inithemi(&hemi, rcol, r, wt);
712 greg 2.19 divcnt = hemi.nt * hemi.np;
713 greg 2.17 /* initialize */
714     if (pg != NULL)
715     pg[0] = pg[1] = pg[2] = 0.0;
716     if (dg != NULL)
717     dg[0] = dg[1] = dg[2] = 0.0;
718 greg 2.23 setcolor(rcol, 0.0, 0.0, 0.0);
719 greg 2.19 if (divcnt == 0)
720 greg 1.1 return(0.0);
721 greg 2.14 /* allocate super-samples */
722 greg 2.15 if (hemi.ns > 0 || pg != NULL || dg != NULL) {
723 greg 2.19 div = (AMBSAMP *)malloc(divcnt*sizeof(AMBSAMP));
724 greg 1.1 if (div == NULL)
725     error(SYSTEM, "out of memory in doambient");
726     } else
727     div = NULL;
728     /* sample the divisions */
729     arad = 0.0;
730 greg 2.23 acol[0] = acol[1] = acol[2] = 0.0;
731 greg 1.1 if ((dp = div) == NULL)
732     dp = &dnew;
733 greg 2.19 divcnt = 0;
734 greg 1.1 for (i = 0; i < hemi.nt; i++)
735     for (j = 0; j < hemi.np; j++) {
736     dp->t = i; dp->p = j;
737     setcolor(dp->v, 0.0, 0.0, 0.0);
738 greg 1.2 dp->r = 0.0;
739 greg 1.1 dp->n = 0;
740 greg 2.16 if (divsample(dp, &hemi, r) < 0) {
741 greg 2.19 if (div != NULL)
742     dp++;
743 greg 2.16 continue;
744     }
745 greg 2.6 arad += dp->r;
746 greg 2.19 divcnt++;
747 greg 1.1 if (div != NULL)
748     dp++;
749 greg 2.6 else
750 greg 1.1 addcolor(acol, dp->v);
751     }
752 greg 2.21 if (!divcnt) {
753     if (div != NULL)
754     free((void *)div);
755 greg 2.19 return(0.0); /* no samples taken */
756 greg 2.21 }
757 greg 2.19 if (divcnt < hemi.nt*hemi.np) {
758     pg = dg = NULL; /* incomplete sampling */
759     hemi.ns = 0;
760     } else if (arad > FTINY && divcnt/arad < minarad) {
761 greg 2.15 hemi.ns = 0; /* close enough */
762 greg 2.19 } else if (hemi.ns > 0) { /* else perform super-sampling? */
763 greg 1.4 comperrs(div, &hemi); /* compute errors */
764 greg 2.19 qsort(div, divcnt, sizeof(AMBSAMP), ambcmp); /* sort divs */
765 greg 1.1 /* super-sample */
766 greg 2.15 for (i = hemi.ns; i > 0; i--) {
767 schorsch 2.11 dnew = *div;
768 greg 2.16 if (divsample(&dnew, &hemi, r) < 0) {
769     dp++;
770     continue;
771     }
772     dp = div; /* reinsert */
773 greg 2.19 j = divcnt < i ? divcnt : i;
774 greg 1.1 while (--j > 0 && dnew.k < dp[1].k) {
775 schorsch 2.11 *dp = *(dp+1);
776 greg 1.1 dp++;
777     }
778 schorsch 2.11 *dp = dnew;
779 greg 1.1 }
780 greg 1.2 if (pg != NULL || dg != NULL) /* restore order */
781 greg 2.19 qsort(div, divcnt, sizeof(AMBSAMP), ambnorm);
782 greg 1.1 }
783     /* compute returned values */
784 greg 1.3 if (div != NULL) {
785 greg 2.19 arad = 0.0; /* note: divcnt may be < nt*np */
786     for (i = hemi.nt*hemi.np, dp = div; i-- > 0; dp++) {
787 greg 1.3 arad += dp->r;
788     if (dp->n > 1) {
789     b = 1.0/dp->n;
790     scalecolor(dp->v, b);
791     dp->r *= b;
792     dp->n = 1;
793     }
794     addcolor(acol, dp->v);
795     }
796 greg 1.5 b = bright(acol);
797 greg 1.6 if (b > FTINY) {
798 greg 2.17 b = 1.0/b; /* compute & normalize gradient(s) */
799 greg 1.6 if (pg != NULL) {
800     posgradient(pg, div, &hemi);
801     for (i = 0; i < 3; i++)
802     pg[i] *= b;
803     }
804     if (dg != NULL) {
805     dirgradient(dg, div, &hemi);
806     for (i = 0; i < 3; i++)
807     dg[i] *= b;
808     }
809 greg 1.5 }
810 greg 2.9 free((void *)div);
811 greg 1.3 }
812 greg 2.23 copycolor(rcol, acol);
813 greg 1.1 if (arad <= FTINY)
814 greg 1.16 arad = maxarad;
815 greg 2.3 else
816 greg 2.19 arad = (divcnt+hemi.ns)/arad;
817 greg 1.15 if (pg != NULL) { /* reduce radius if gradient large */
818     d = DOT(pg,pg);
819     if (d*arad*arad > 1.0)
820     arad = 1.0/sqrt(d);
821     }
822 greg 1.16 if (arad < minarad) {
823 greg 1.1 arad = minarad;
824 greg 1.16 if (pg != NULL && d*arad*arad > 1.0) { /* cap gradient */
825     d = 1.0/arad/sqrt(d);
826     for (i = 0; i < 3; i++)
827     pg[i] *= d;
828     }
829     }
830 greg 2.3 if ((arad /= sqrt(wt)) > maxarad)
831     arad = maxarad;
832     return(arad);
833 greg 1.1 }
834    
835    
836 greg 2.9 void
837 greg 2.14 comperrs( /* compute initial error estimates */
838     AMBSAMP *da, /* assumes standard ordering */
839 greg 2.23 AMBHEMI *hp
840 greg 2.14 )
841 greg 1.1 {
842     double b, b2;
843     int i, j;
844 greg 2.23 AMBSAMP *dp;
845 greg 1.1 /* sum differences from neighbors */
846     dp = da;
847     for (i = 0; i < hp->nt; i++)
848     for (j = 0; j < hp->np; j++) {
849 greg 1.6 #ifdef DEBUG
850     if (dp->t != i || dp->p != j)
851     error(CONSISTENCY,
852     "division order in comperrs");
853     #endif
854 greg 1.1 b = bright(dp[0].v);
855     if (i > 0) { /* from above */
856     b2 = bright(dp[-hp->np].v) - b;
857     b2 *= b2 * 0.25;
858     dp[0].k += b2;
859     dp[-hp->np].k += b2;
860     }
861     if (j > 0) { /* from behind */
862     b2 = bright(dp[-1].v) - b;
863     b2 *= b2 * 0.25;
864     dp[0].k += b2;
865     dp[-1].k += b2;
866 greg 1.4 } else { /* around */
867     b2 = bright(dp[hp->np-1].v) - b;
868 greg 1.1 b2 *= b2 * 0.25;
869     dp[0].k += b2;
870 greg 1.4 dp[hp->np-1].k += b2;
871 greg 1.1 }
872     dp++;
873     }
874     /* divide by number of neighbors */
875     dp = da;
876     for (j = 0; j < hp->np; j++) /* top row */
877     (dp++)->k *= 1.0/3.0;
878     if (hp->nt < 2)
879     return;
880     for (i = 1; i < hp->nt-1; i++) /* central region */
881     for (j = 0; j < hp->np; j++)
882     (dp++)->k *= 0.25;
883     for (j = 0; j < hp->np; j++) /* bottom row */
884     (dp++)->k *= 1.0/3.0;
885     }
886    
887    
888 greg 2.9 void
889 greg 2.14 posgradient( /* compute position gradient */
890     FVECT gv,
891     AMBSAMP *da, /* assumes standard ordering */
892 greg 2.23 AMBHEMI *hp
893 greg 2.14 )
894 greg 1.1 {
895 greg 2.23 int i, j;
896 greg 2.2 double nextsine, lastsine, b, d;
897 greg 1.2 double mag0, mag1;
898     double phi, cosp, sinp, xd, yd;
899 greg 2.23 AMBSAMP *dp;
900 greg 1.2
901     xd = yd = 0.0;
902     for (j = 0; j < hp->np; j++) {
903     dp = da + j;
904     mag0 = mag1 = 0.0;
905 greg 2.2 lastsine = 0.0;
906 greg 1.2 for (i = 0; i < hp->nt; i++) {
907     #ifdef DEBUG
908     if (dp->t != i || dp->p != j)
909     error(CONSISTENCY,
910     "division order in posgradient");
911     #endif
912     b = bright(dp->v);
913     if (i > 0) {
914     d = dp[-hp->np].r;
915     if (dp[0].r > d) d = dp[0].r;
916 greg 2.2 /* sin(t)*cos(t)^2 */
917     d *= lastsine * (1.0 - (double)i/hp->nt);
918 greg 1.2 mag0 += d*(b - bright(dp[-hp->np].v));
919     }
920 greg 2.2 nextsine = sqrt((double)(i+1)/hp->nt);
921 greg 1.2 if (j > 0) {
922     d = dp[-1].r;
923     if (dp[0].r > d) d = dp[0].r;
924 greg 2.2 mag1 += d * (nextsine - lastsine) *
925     (b - bright(dp[-1].v));
926 greg 1.2 } else {
927     d = dp[hp->np-1].r;
928     if (dp[0].r > d) d = dp[0].r;
929 greg 2.2 mag1 += d * (nextsine - lastsine) *
930     (b - bright(dp[hp->np-1].v));
931 greg 1.2 }
932     dp += hp->np;
933 greg 2.2 lastsine = nextsine;
934 greg 1.2 }
935 greg 2.2 mag0 *= 2.0*PI / hp->np;
936 greg 1.2 phi = 2.0*PI * (double)j/hp->np;
937 gwlarson 2.8 cosp = tcos(phi); sinp = tsin(phi);
938 greg 1.2 xd += mag0*cosp - mag1*sinp;
939     yd += mag0*sinp + mag1*cosp;
940     }
941     for (i = 0; i < 3; i++)
942 greg 2.16 gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])*(hp->nt*hp->np)/PI;
943 greg 1.1 }
944    
945    
946 greg 2.9 void
947 greg 2.14 dirgradient( /* compute direction gradient */
948     FVECT gv,
949     AMBSAMP *da, /* assumes standard ordering */
950 greg 2.23 AMBHEMI *hp
951 greg 2.14 )
952 greg 1.1 {
953 greg 2.23 int i, j;
954 greg 1.2 double mag;
955     double phi, xd, yd;
956 greg 2.23 AMBSAMP *dp;
957 greg 1.2
958     xd = yd = 0.0;
959     for (j = 0; j < hp->np; j++) {
960     dp = da + j;
961     mag = 0.0;
962     for (i = 0; i < hp->nt; i++) {
963     #ifdef DEBUG
964     if (dp->t != i || dp->p != j)
965     error(CONSISTENCY,
966     "division order in dirgradient");
967     #endif
968 greg 2.2 /* tan(t) */
969     mag += bright(dp->v)/sqrt(hp->nt/(i+.5) - 1.0);
970 greg 1.2 dp += hp->np;
971     }
972     phi = 2.0*PI * (j+.5)/hp->np + PI/2.0;
973 gwlarson 2.8 xd += mag * tcos(phi);
974     yd += mag * tsin(phi);
975 greg 1.2 }
976     for (i = 0; i < 3; i++)
977 greg 2.16 gv[i] = xd*hp->ux[i] + yd*hp->uy[i];
978 greg 1.1 }
979 greg 2.25
980     #endif /* ! NEWAMB */