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root/radiance/ray/src/common/bsdf_m.c
Revision: 3.5
Committed: Sat Feb 19 23:42:09 2011 UTC (13 years, 2 months ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 3.4: +53 -66 lines
Log Message:
Fixes to BSDF including blurring of angle boundaries

File Contents

# User Rev Content
1 greg 3.2 #ifndef lint
2 greg 3.5 static const char RCSid[] = "$Id: bsdf_m.c,v 3.4 2011/02/19 01:48:59 greg Exp $";
3 greg 3.2 #endif
4 greg 3.1 /*
5     * bsdf_m.c
6     *
7     * Definitions supporting BSDF matrices
8     *
9     * Created by Greg Ward on 2/2/11.
10     * Copyright 2011 Anyhere Software. All rights reserved.
11     *
12     */
13    
14 greg 3.3 #include "rtio.h"
15 greg 3.1 #include <stdlib.h>
16     #include <math.h>
17     #include <ctype.h>
18     #include "ezxml.h"
19     #include "bsdf.h"
20     #include "bsdf_m.h"
21    
22     /* Function return codes */
23     #define RC_GOOD 1
24     #define RC_FAIL 0
25     #define RC_FORMERR (-1)
26     #define RC_DATERR (-2)
27     #define RC_UNSUPP (-3)
28     #define RC_INTERR (-4)
29     #define RC_MEMERR (-5)
30    
31     #define MAXLATS 46 /* maximum number of latitudes */
32    
33     /* BSDF angle specification */
34     typedef struct {
35     char name[64]; /* basis name */
36     int nangles; /* total number of directions */
37     struct {
38     float tmin; /* starting theta */
39     int nphis; /* number of phis (0 term) */
40     } lat[MAXLATS+1]; /* latitudes */
41     } ANGLE_BASIS;
42    
43     #define MAXABASES 7 /* limit on defined bases */
44    
45     static ANGLE_BASIS abase_list[MAXABASES] = {
46     {
47     "LBNL/Klems Full", 145,
48     { {-5., 1},
49     {5., 8},
50     {15., 16},
51     {25., 20},
52     {35., 24},
53     {45., 24},
54     {55., 24},
55     {65., 16},
56     {75., 12},
57     {90., 0} }
58     }, {
59     "LBNL/Klems Half", 73,
60     { {-6.5, 1},
61     {6.5, 8},
62     {19.5, 12},
63     {32.5, 16},
64     {46.5, 20},
65     {61.5, 12},
66     {76.5, 4},
67     {90., 0} }
68     }, {
69     "LBNL/Klems Quarter", 41,
70     { {-9., 1},
71     {9., 8},
72     {27., 12},
73     {46., 12},
74     {66., 8},
75     {90., 0} }
76     }
77     };
78    
79     static int nabases = 3; /* current number of defined bases */
80    
81     static int
82     fequal(double a, double b)
83     {
84     if (b != .0)
85     a = a/b - 1.;
86     return (a <= 1e-6) & (a >= -1e-6);
87     }
88    
89     /* returns the name of the given tag */
90     #ifdef ezxml_name
91     #undef ezxml_name
92     static char *
93     ezxml_name(ezxml_t xml)
94     {
95     if (xml == NULL)
96     return NULL;
97     return xml->name;
98     }
99     #endif
100    
101     /* returns the given tag's character content or empty string if none */
102     #ifdef ezxml_txt
103     #undef ezxml_txt
104     static char *
105     ezxml_txt(ezxml_t xml)
106     {
107     if (xml == NULL)
108     return "";
109     return xml->txt;
110     }
111     #endif
112    
113     /* Convert error to standard BSDF code */
114     static SDError
115     convert_errcode(int ec)
116     {
117     switch (ec) {
118     case RC_GOOD:
119     return SDEnone;
120     case RC_FORMERR:
121     return SDEformat;
122     case RC_DATERR:
123     return SDEdata;
124     case RC_UNSUPP:
125     return SDEsupport;
126     case RC_INTERR:
127     return SDEinternal;
128     case RC_MEMERR:
129     return SDEmemory;
130     }
131     return SDEunknown;
132     }
133    
134     /* Allocate a BSDF matrix of the given size */
135     static SDMat *
136     SDnewMatrix(int ni, int no)
137     {
138     SDMat *sm;
139    
140     if ((ni <= 0) | (no <= 0)) {
141     strcpy(SDerrorDetail, "Empty BSDF matrix request");
142     return NULL;
143     }
144     sm = (SDMat *)malloc(sizeof(SDMat) + (ni*no - 1)*sizeof(float));
145     if (sm == NULL) {
146     sprintf(SDerrorDetail, "Cannot allocate %dx%d BSDF matrix",
147     ni, no);
148     return NULL;
149     }
150     memset(sm, 0, sizeof(SDMat)-sizeof(float));
151     sm->ninc = ni;
152     sm->nout = no;
153    
154     return sm;
155     }
156    
157     /* Free a BSDF matrix */
158     #define SDfreeMatrix free
159    
160     /* get vector for this angle basis index */
161     static int
162     ab_getvec(FVECT v, int ndx, double randX, void *p)
163     {
164     ANGLE_BASIS *ab = (ANGLE_BASIS *)p;
165     double rx[2];
166     int li;
167     double pol, azi, d;
168    
169     if ((ndx < 0) | (ndx >= ab->nangles))
170     return RC_FAIL;
171     for (li = 0; ndx >= ab->lat[li].nphis; li++)
172     ndx -= ab->lat[li].nphis;
173     SDmultiSamp(rx, 2, randX);
174     pol = M_PI/180.*( (1.-rx[0])*ab->lat[li].tmin +
175     rx[0]*ab->lat[li+1].tmin );
176     azi = 2.*M_PI*(ndx + rx[1] - .5)/ab->lat[li].nphis;
177     v[2] = d = cos(pol);
178     d = sqrt(1. - d*d); /* sin(pol) */
179     v[0] = cos(azi)*d;
180     v[1] = sin(azi)*d;
181     return RC_GOOD;
182     }
183    
184     /* get index corresponding to the given vector */
185     static int
186     ab_getndx(const FVECT v, void *p)
187     {
188     ANGLE_BASIS *ab = (ANGLE_BASIS *)p;
189     int li, ndx;
190     double pol, azi, d;
191    
192     if (v == NULL)
193     return -1;
194     if ((v[2] < .0) | (v[2] > 1.0))
195     return -1;
196     pol = 180.0/M_PI*acos(v[2]);
197     azi = 180.0/M_PI*atan2(v[1], v[0]);
198     if (azi < 0.0) azi += 360.0;
199     for (li = 1; ab->lat[li].tmin <= pol; li++)
200     if (!ab->lat[li].nphis)
201     return -1;
202     --li;
203     ndx = (int)((1./360.)*azi*ab->lat[li].nphis + 0.5);
204     if (ndx >= ab->lat[li].nphis) ndx = 0;
205     while (li--)
206     ndx += ab->lat[li].nphis;
207     return ndx;
208     }
209    
210     /* compute square of real value */
211     static double sq(double x) { return x*x; }
212    
213     /* get projected solid angle for this angle basis index */
214     static double
215     ab_getohm(int ndx, void *p)
216     {
217     static int last_li = -1;
218     static double last_ohm;
219     ANGLE_BASIS *ab = (ANGLE_BASIS *)p;
220     int li;
221     double theta, theta1;
222    
223     if ((ndx < 0) | (ndx >= ab->nangles))
224     return -1.;
225     for (li = 0; ndx >= ab->lat[li].nphis; li++)
226     ndx -= ab->lat[li].nphis;
227     if (li == last_li) /* cached latitude? */
228     return last_ohm;
229     last_li = li;
230     theta1 = M_PI/180. * ab->lat[li+1].tmin;
231     if (ab->lat[li].nphis == 1) /* special case */
232     return last_ohm = M_PI*(1. - sq(cos(theta1)));
233     theta = M_PI/180. * ab->lat[li].tmin;
234     return last_ohm = M_PI*(sq(cos(theta)) - sq(cos(theta1))) /
235     (double)ab->lat[li].nphis;
236     }
237    
238     /* get reverse vector for this angle basis index */
239     static int
240     ab_getvecR(FVECT v, int ndx, double randX, void *p)
241     {
242     int na = (*(ANGLE_BASIS *)p).nangles;
243    
244     if (!ab_getvec(v, ndx, randX, p))
245     return RC_FAIL;
246    
247     v[0] = -v[0];
248     v[1] = -v[1];
249     v[2] = -v[2];
250    
251     return RC_GOOD;
252     }
253    
254     /* get index corresponding to the reverse vector */
255     static int
256     ab_getndxR(const FVECT v, void *p)
257     {
258     FVECT v2;
259    
260     v2[0] = -v[0];
261     v2[1] = -v[1];
262     v2[2] = -v[2];
263    
264     return ab_getndx(v2, p);
265     }
266    
267     /* load custom BSDF angle basis */
268     static int
269     load_angle_basis(ezxml_t wab)
270     {
271     char *abname = ezxml_txt(ezxml_child(wab, "AngleBasisName"));
272     ezxml_t wbb;
273     int i;
274    
275     if (!abname || !*abname)
276     return RC_FAIL;
277     for (i = nabases; i--; )
278     if (!strcasecmp(abname, abase_list[i].name))
279     return RC_GOOD; /* assume it's the same */
280     if (nabases >= MAXABASES) {
281     sprintf(SDerrorDetail, "Out of angle bases reading '%s'",
282     abname);
283     return RC_INTERR;
284     }
285     strcpy(abase_list[nabases].name, abname);
286     abase_list[nabases].nangles = 0;
287     for (i = 0, wbb = ezxml_child(wab, "AngleBasisBlock");
288     wbb != NULL; i++, wbb = wbb->next) {
289     if (i >= MAXLATS) {
290     sprintf(SDerrorDetail, "Too many latitudes for '%s'",
291     abname);
292     return RC_INTERR;
293     }
294     abase_list[nabases].lat[i+1].tmin = atof(ezxml_txt(
295     ezxml_child(ezxml_child(wbb,
296     "ThetaBounds"), "UpperTheta")));
297     if (!i)
298     abase_list[nabases].lat[i].tmin =
299     -abase_list[nabases].lat[i+1].tmin;
300     else if (!fequal(atof(ezxml_txt(ezxml_child(ezxml_child(wbb,
301     "ThetaBounds"), "LowerTheta"))),
302     abase_list[nabases].lat[i].tmin)) {
303     sprintf(SDerrorDetail, "Theta values disagree in '%s'",
304     abname);
305     return RC_DATERR;
306     }
307     abase_list[nabases].nangles +=
308     abase_list[nabases].lat[i].nphis =
309     atoi(ezxml_txt(ezxml_child(wbb, "nPhis")));
310     if (abase_list[nabases].lat[i].nphis <= 0 ||
311     (abase_list[nabases].lat[i].nphis == 1 &&
312     abase_list[nabases].lat[i].tmin > FTINY)) {
313     sprintf(SDerrorDetail, "Illegal phi count in '%s'",
314     abname);
315     return RC_DATERR;
316     }
317     }
318     abase_list[nabases++].lat[i].nphis = 0;
319     return RC_GOOD;
320     }
321    
322     /* compute min. proj. solid angle and max. direct hemispherical scattering */
323     static int
324     get_extrema(SDSpectralDF *df)
325     {
326     SDMat *dp = (SDMat *)df->comp[0].dist;
327     double *ohma;
328     int i, o;
329     /* initialize extrema */
330     df->minProjSA = M_PI;
331     df->maxHemi = .0;
332     ohma = (double *)malloc(dp->nout*sizeof(double));
333     if (ohma == NULL)
334     return RC_MEMERR;
335     /* get outgoing solid angles */
336     for (o = dp->nout; o--; )
337     if ((ohma[o] = mBSDF_outohm(dp,o)) < df->minProjSA)
338     df->minProjSA = ohma[o];
339     /* compute hemispherical sums */
340     for (i = dp->ninc; i--; ) {
341     double hemi = .0;
342     for (o = dp->nout; o--; )
343     hemi += ohma[o] * mBSDF_value(dp, i, o);
344     if (hemi > df->maxHemi)
345     df->maxHemi = hemi;
346     }
347     free(ohma);
348     /* need incoming solid angles, too? */
349 greg 3.5 if ((dp->ib_ohm != dp->ob_ohm) | (dp->ib_priv != dp->ob_priv)) {
350 greg 3.1 double ohm;
351     for (i = dp->ninc; i--; )
352     if ((ohm = mBSDF_incohm(dp,i)) < df->minProjSA)
353     df->minProjSA = ohm;
354     }
355     return (df->maxHemi <= 1.01);
356     }
357    
358     /* load BSDF distribution for this wavelength */
359     static int
360     load_bsdf_data(SDData *sd, ezxml_t wdb, int rowinc)
361     {
362     SDSpectralDF *df;
363     SDMat *dp;
364     char *sdata;
365     int inbi, outbi;
366     int i;
367     /* allocate BSDF component */
368     sdata = ezxml_txt(ezxml_child(wdb, "WavelengthDataDirection"));
369     if (!strcasecmp(sdata, "Transmission Front")) {
370     if (sd->tf != NULL)
371     SDfreeSpectralDF(sd->tf);
372     if ((sd->tf = SDnewSpectralDF(1)) == NULL)
373     return RC_MEMERR;
374     df = sd->tf;
375     } else if (!strcasecmp(sdata, "Reflection Front")) {
376     if (sd->rf != NULL)
377     SDfreeSpectralDF(sd->rf);
378     if ((sd->rf = SDnewSpectralDF(1)) == NULL)
379     return RC_MEMERR;
380     df = sd->rf;
381     } else if (!strcasecmp(sdata, "Reflection Back")) {
382     if (sd->rb != NULL)
383     SDfreeSpectralDF(sd->rb);
384     if ((sd->rb = SDnewSpectralDF(1)) == NULL)
385     return RC_MEMERR;
386     df = sd->rb;
387     } else
388     return RC_FAIL;
389 greg 3.4 /* XXX should also check "ScatteringDataType" for consistency? */
390 greg 3.1 /* get angle bases */
391     sdata = ezxml_txt(ezxml_child(wdb,"ColumnAngleBasis"));
392     if (!sdata || !*sdata) {
393     sprintf(SDerrorDetail, "Missing column basis for BSDF '%s'",
394     sd->name);
395     return RC_FORMERR;
396     }
397     for (inbi = nabases; inbi--; )
398 greg 3.4 if (!strcasecmp(sdata, abase_list[inbi].name))
399 greg 3.1 break;
400     if (inbi < 0) {
401 greg 3.4 sprintf(SDerrorDetail, "Undefined ColumnAngleBasis '%s'", sdata);
402 greg 3.1 return RC_FORMERR;
403     }
404     sdata = ezxml_txt(ezxml_child(wdb,"RowAngleBasis"));
405     if (!sdata || !*sdata) {
406     sprintf(SDerrorDetail, "Missing row basis for BSDF '%s'",
407     sd->name);
408     return RC_FORMERR;
409     }
410     for (outbi = nabases; outbi--; )
411 greg 3.4 if (!strcasecmp(sdata, abase_list[outbi].name))
412 greg 3.1 break;
413     if (outbi < 0) {
414 greg 3.4 sprintf(SDerrorDetail, "Undefined RowAngleBasis '%s'", sdata);
415 greg 3.1 return RC_FORMERR;
416     }
417     /* allocate BSDF matrix */
418     dp = SDnewMatrix(abase_list[inbi].nangles, abase_list[outbi].nangles);
419     if (dp == NULL)
420     return RC_MEMERR;
421 greg 3.5 dp->ib_priv = &abase_list[inbi];
422     dp->ob_priv = &abase_list[outbi];
423 greg 3.1 if (df == sd->tf) {
424 greg 3.5 dp->ib_vec = &ab_getvecR;
425     dp->ib_ndx = &ab_getndxR;
426     dp->ob_vec = &ab_getvec;
427     dp->ob_ndx = &ab_getndx;
428 greg 3.1 } else if (df == sd->rf) {
429 greg 3.5 dp->ib_vec = &ab_getvec;
430     dp->ib_ndx = &ab_getndx;
431     dp->ob_vec = &ab_getvec;
432     dp->ob_ndx = &ab_getndx;
433 greg 3.1 } else /* df == sd->rb */ {
434 greg 3.5 dp->ib_vec = &ab_getvecR;
435     dp->ib_ndx = &ab_getndxR;
436     dp->ob_vec = &ab_getvecR;
437     dp->ob_ndx = &ab_getndxR;
438 greg 3.1 }
439 greg 3.5 dp->ib_ohm = &ab_getohm;
440     dp->ob_ohm = &ab_getohm;
441 greg 3.1 df->comp[0].cspec[0] = c_dfcolor; /* XXX monochrome for now */
442     df->comp[0].dist = dp;
443     df->comp[0].func = &SDhandleMtx;
444     /* read BSDF data */
445     sdata = ezxml_txt(ezxml_child(wdb,"ScatteringData"));
446     if (!sdata || !*sdata) {
447     sprintf(SDerrorDetail, "Missing BSDF ScatteringData in '%s'",
448     sd->name);
449     return RC_FORMERR;
450     }
451     for (i = 0; i < dp->ninc*dp->nout; i++) {
452 greg 3.3 char *sdnext = fskip(sdata);
453 greg 3.1 if (sdnext == NULL) {
454     sprintf(SDerrorDetail,
455     "Bad/missing BSDF ScatteringData in '%s'",
456     sd->name);
457     return RC_FORMERR;
458     }
459     while (*sdnext && isspace(*sdnext))
460     sdnext++;
461     if (*sdnext == ',') sdnext++;
462     if (rowinc) {
463     int r = i/dp->nout;
464     int c = i - c*dp->nout;
465     mBSDF_value(dp,r,c) = atof(sdata);
466     } else
467     dp->bsdf[i] = atof(sdata);
468     sdata = sdnext;
469     }
470     return get_extrema(df);
471     }
472    
473     /* Subtract minimum (diffuse) scattering amount from BSDF */
474     static double
475     subtract_min(SDMat *sm)
476     {
477     float minv = sm->bsdf[0];
478     int n = sm->ninc*sm->nout;
479     int i;
480    
481     for (i = n; --i; )
482     if (sm->bsdf[i] < minv)
483     minv = sm->bsdf[i];
484     for (i = n; i--; )
485     sm->bsdf[i] -= minv;
486    
487     return minv*M_PI; /* be sure to include multiplier */
488     }
489    
490     /* Extract and separate diffuse portion of BSDF */
491     static void
492     extract_diffuse(SDValue *dv, SDSpectralDF *df)
493     {
494     int n;
495    
496     if (df == NULL || df->ncomp <= 0) {
497     dv->spec = c_dfcolor;
498     dv->cieY = .0;
499     return;
500     }
501     dv->spec = df->comp[0].cspec[0];
502     dv->cieY = subtract_min((SDMat *)df->comp[0].dist);
503     /* in case of multiple components */
504     for (n = df->ncomp; --n; ) {
505     double ymin = subtract_min((SDMat *)df->comp[n].dist);
506     c_cmix(&dv->spec, dv->cieY, &dv->spec, ymin, &df->comp[n].cspec[0]);
507     dv->cieY += ymin;
508     }
509 greg 3.4 df->maxHemi -= dv->cieY; /* adjust minimum hemispherical */
510     /* make sure everything is set */
511 greg 3.1 c_ccvt(&dv->spec, C_CSXY+C_CSSPEC);
512     }
513    
514     /* Load a BSDF matrix from an open XML file */
515     SDError
516 greg 3.4 SDloadMtx(SDData *sd, ezxml_t wtl)
517 greg 3.1 {
518 greg 3.4 ezxml_t wld, wdb;
519 greg 3.1 int rowIn;
520     struct BSDF_data *dp;
521     char *txt;
522     int rval;
523    
524 greg 3.4 txt = ezxml_txt(ezxml_child(ezxml_child(wtl,
525     "DataDefinition"), "IncidentDataStructure"));
526     if (txt == NULL || !*txt) {
527 greg 3.1 sprintf(SDerrorDetail,
528 greg 3.4 "BSDF \"%s\": missing IncidentDataStructure",
529 greg 3.1 sd->name);
530     return SDEformat;
531     }
532     if (!strcasecmp(txt, "Rows"))
533     rowIn = 1;
534     else if (!strcasecmp(txt, "Columns"))
535     rowIn = 0;
536     else {
537     sprintf(SDerrorDetail,
538     "BSDF \"%s\": unsupported IncidentDataStructure",
539     sd->name);
540     return SDEsupport;
541     }
542     /* get angle basis */
543     rval = load_angle_basis(ezxml_child(ezxml_child(wtl,
544     "DataDefinition"), "AngleBasis"));
545     if (rval < 0)
546 greg 3.4 return convert_errcode(rval);
547 greg 3.1 /* load BSDF components */
548     for (wld = ezxml_child(wtl, "WavelengthData");
549     wld != NULL; wld = wld->next) {
550     if (strcasecmp(ezxml_txt(ezxml_child(wld,"Wavelength")),
551     "Visible"))
552     continue; /* just visible for now */
553     for (wdb = ezxml_child(wld, "WavelengthDataBlock");
554     wdb != NULL; wdb = wdb->next)
555     if ((rval = load_bsdf_data(sd, wdb, rowIn)) < 0)
556 greg 3.4 return convert_errcode(rval);
557 greg 3.1 }
558     /* separate diffuse components */
559     extract_diffuse(&sd->rLambFront, sd->rf);
560     extract_diffuse(&sd->rLambBack, sd->rb);
561     extract_diffuse(&sd->tLamb, sd->tf);
562     /* return success */
563     return SDEnone;
564     }
565    
566     /* Get Matrix BSDF value */
567     static int
568     SDgetMtxBSDF(float coef[SDmaxCh], const FVECT outVec,
569     const FVECT inVec, const void *dist)
570     {
571     const SDMat *dp = (const SDMat *)dist;
572     int i_ndx, o_ndx;
573     /* get angle indices */
574     i_ndx = mBSDF_incndx(dp, inVec);
575     o_ndx = mBSDF_outndx(dp, outVec);
576     /* try reciprocity if necessary */
577     if ((i_ndx < 0) & (o_ndx < 0)) {
578     i_ndx = mBSDF_incndx(dp, outVec);
579     o_ndx = mBSDF_outndx(dp, inVec);
580     }
581     if ((i_ndx < 0) | (o_ndx < 0))
582     return 0; /* nothing from this component */
583     coef[0] = mBSDF_value(dp, i_ndx, o_ndx);
584     return 1; /* XXX monochrome for now */
585     }
586    
587     /* Query solid angle for vector */
588     static SDError
589     SDqueryMtxProjSA(double *psa, const FVECT vec, int qflags, const void *dist)
590     {
591     const SDMat *dp = (const SDMat *)dist;
592 greg 3.5 double inc_psa, out_psa;
593     /* check arguments */
594     if ((psa == NULL) | (vec == NULL) | (dp == NULL))
595 greg 3.1 return SDEargument;
596 greg 3.5 /* get projected solid angles */
597     inc_psa = mBSDF_incohm(dp, mBSDF_incndx(dp, vec));
598     out_psa = mBSDF_outohm(dp, mBSDF_outndx(dp, vec));
599    
600     switch (qflags) { /* record based on flag settings */
601     case SDqueryVal:
602     psa[0] = .0;
603     /* fall through */
604     case SDqueryMax:
605     if (inc_psa > psa[0])
606     psa[0] = inc_psa;
607     if (out_psa > psa[0])
608     psa[0] = out_psa;
609     break;
610     case SDqueryMin+SDqueryMax:
611     if (inc_psa > psa[0])
612     psa[1] = inc_psa;
613     if (out_psa > psa[0])
614     psa[1] = out_psa;
615     /* fall through */
616     case SDqueryMin:
617     if ((inc_psa > .0) & (inc_psa < psa[0]))
618 greg 3.1 psa[0] = inc_psa;
619 greg 3.5 if ((out_psa > .0) & (out_psa < psa[0]))
620     psa[0] = out_psa;
621     break;
622 greg 3.1 }
623 greg 3.5 /* make sure it's legal */
624     return (psa[0] <= .0) ? SDEinternal : SDEnone;
625 greg 3.1 }
626    
627     /* Compute new cumulative distribution from BSDF */
628     static int
629     make_cdist(SDMatCDst *cd, const FVECT inVec, SDMat *dp, int rev)
630     {
631     const unsigned maxval = ~0;
632     double *cmtab, scale;
633     int o;
634    
635     cmtab = (double *)malloc((cd->calen+1)*sizeof(double));
636     if (cmtab == NULL)
637     return 0;
638     cmtab[0] = .0;
639     for (o = 0; o < cd->calen; o++) {
640     if (rev)
641     cmtab[o+1] = mBSDF_value(dp, o, cd->indx) *
642     (*dp->ib_ohm)(o, dp->ib_priv);
643     else
644     cmtab[o+1] = mBSDF_value(dp, cd->indx, o) *
645     (*dp->ob_ohm)(o, dp->ob_priv);
646     cmtab[o+1] += cmtab[o];
647     }
648     cd->cTotal = cmtab[cd->calen];
649     scale = (double)maxval / cd->cTotal;
650     cd->carr[0] = 0;
651     for (o = 1; o < cd->calen; o++)
652     cd->carr[o] = scale*cmtab[o] + .5;
653     cd->carr[cd->calen] = maxval;
654     free(cmtab);
655     return 1;
656     }
657    
658     /* Get cumulative distribution for matrix BSDF */
659     static const SDCDst *
660     SDgetMtxCDist(const FVECT inVec, SDComponent *sdc)
661     {
662     SDMat *dp = (SDMat *)sdc->dist;
663     int reverse;
664     SDMatCDst myCD;
665     SDMatCDst *cd, *cdlast;
666 greg 3.5 /* check arguments */
667     if ((inVec == NULL) | (dp == NULL))
668 greg 3.1 return NULL;
669     memset(&myCD, 0, sizeof(myCD));
670     myCD.indx = mBSDF_incndx(dp, inVec);
671     if (myCD.indx >= 0) {
672     myCD.ob_priv = dp->ob_priv;
673     myCD.ob_vec = dp->ob_vec;
674     myCD.calen = dp->nout;
675     reverse = 0;
676     } else { /* try reciprocity */
677     myCD.indx = mBSDF_outndx(dp, inVec);
678     if (myCD.indx < 0)
679     return NULL;
680     myCD.ob_priv = dp->ib_priv;
681     myCD.ob_vec = dp->ib_vec;
682     myCD.calen = dp->ninc;
683     reverse = 1;
684     }
685     cdlast = NULL; /* check for it in cache list */
686     for (cd = (SDMatCDst *)sdc->cdList;
687     cd != NULL; cd = (SDMatCDst *)cd->next) {
688     if (cd->indx == myCD.indx && (cd->calen == myCD.calen) &
689     (cd->ob_priv == myCD.ob_priv) &
690     (cd->ob_vec == myCD.ob_vec))
691     break;
692     cdlast = cd;
693     }
694     if (cd == NULL) { /* need to allocate new entry */
695     cd = (SDMatCDst *)malloc(sizeof(SDMatCDst) +
696     myCD.calen*sizeof(myCD.carr[0]));
697     if (cd == NULL)
698     return NULL;
699     *cd = myCD; /* compute cumulative distribution */
700     if (!make_cdist(cd, inVec, dp, reverse)) {
701     free(cd);
702     return NULL;
703     }
704     cdlast = cd;
705     }
706     if (cdlast != NULL) { /* move entry to head of cache list */
707     cdlast->next = cd->next;
708     cd->next = sdc->cdList;
709     sdc->cdList = (SDCDst *)cd;
710     }
711     return (SDCDst *)cd; /* ready to go */
712     }
713    
714     /* Sample cumulative distribution */
715     static SDError
716     SDsampMtxCDist(FVECT outVec, double randX, const SDCDst *cdp)
717     {
718     const unsigned maxval = ~0;
719     const SDMatCDst *mcd = (const SDMatCDst *)cdp;
720     const unsigned target = randX*maxval;
721     int i, iupper, ilower;
722 greg 3.5 /* check arguments */
723     if ((outVec == NULL) | (mcd == NULL))
724     return SDEargument;
725 greg 3.1 /* binary search to find index */
726     ilower = 0; iupper = mcd->calen;
727     while ((i = (iupper + ilower) >> 1) != ilower)
728     if ((long)target >= (long)mcd->carr[i])
729     ilower = i;
730     else
731     iupper = i;
732     /* localize random position */
733     randX = (randX*maxval - mcd->carr[ilower]) /
734     (double)(mcd->carr[iupper] - mcd->carr[ilower]);
735     /* convert index to vector */
736     if ((*mcd->ob_vec)(outVec, i, randX, mcd->ob_priv))
737     return SDEnone;
738     strcpy(SDerrorDetail, "BSDF sampling fault");
739     return SDEinternal;
740     }
741    
742     /* Fixed resolution BSDF methods */
743     SDFunc SDhandleMtx = {
744     &SDgetMtxBSDF,
745     &SDqueryMtxProjSA,
746     &SDgetMtxCDist,
747     &SDsampMtxCDist,
748     &SDfreeMatrix,
749     };