src/common/bsdf.c

#ifndef lint
static const char RCSid[] = "$Id: bsdf.c,v 2.41 2012/06/23 16:47:39 greg Exp $";
#endif
/*
 *  bsdf.c
 *  
 *  Definitions for bidirectional scattering distribution functions.
 *
 *  Created by Greg Ward on 1/10/11.
 *
 */

#define _USE_MATH_DEFINES
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <ctype.h>
#include "ezxml.h"
#include "hilbert.h"
#include "bsdf.h"
#include "bsdf_m.h"
#include "bsdf_t.h"

/* English ASCII strings corresponding to ennumerated errors */
const char              *SDerrorEnglish[] = {
                                "No error",
                                "Memory error",
                                "File input/output error",
                                "File format error",
                                "Illegal argument",
                                "Invalid data",
                                "Unsupported feature",
                                "Internal program error",
                                "Unknown error"
                        };

/* Additional information on last error (ASCII English) */
char                    SDerrorDetail[256];

/* Empty distribution for getCDist() calls that fail for some reason */
const SDCDst            SDemptyCD;

/* Cache of loaded BSDFs */
struct SDCache_s        *SDcacheList = NULL;

/* Retain BSDFs in cache list */
int                     SDretainSet = SDretainNone;

/* Report any error to the indicated stream (in English) */
SDError
SDreportEnglish(SDError ec, FILE *fp)
{
        if (!ec)
                return SDEnone;
        if ((ec < SDEnone) | (ec > SDEunknown)) {
                SDerrorDetail[0] = '\0';
                ec = SDEunknown;
        }
        if (fp == NULL)
                return ec;
        fputs(SDerrorEnglish[ec], fp);
        if (SDerrorDetail[0]) {
                fputs(": ", fp);
                fputs(SDerrorDetail, fp);
        }
        fputc('\n', fp);
        if (fp != stderr)
                fflush(fp);
        return ec;
}

static double
to_meters(              /* return factor to convert given unit to meters */
        const char *unit
)
{
        if (unit == NULL) return(1.);           /* safe assumption? */
        if (!strcasecmp(unit, "Meter")) return(1.);
        if (!strcasecmp(unit, "Foot")) return(.3048);
        if (!strcasecmp(unit, "Inch")) return(.0254);
        if (!strcasecmp(unit, "Centimeter")) return(.01);
        if (!strcasecmp(unit, "Millimeter")) return(.001);
        sprintf(SDerrorDetail, "Unknown dimensional unit '%s'", unit);
        return(-1.);
}

/* Load geometric dimensions and description (if any) */
static SDError
SDloadGeometry(SDData *sd, ezxml_t wdb)
{
        ezxml_t         geom;
        double          cfact;
        const char      *fmt, *mgfstr;

        if (wdb == NULL)                /* no geometry section? */
                return SDEnone;
        if ((geom = ezxml_child(wdb, "Name")) != NULL) {
                strncpy(sd->matn, ezxml_txt(geom), SDnameLn);
                if (sd->matn[SDnameLn-1])
                        strcpy(sd->matn+(SDnameLn-4), "...");
        }
        if ((geom = ezxml_child(wdb, "Manufacturer")) != NULL) {
                strncpy(sd->makr, ezxml_txt(geom), SDnameLn);
                if (sd->makr[SDnameLn-1])
                        strcpy(sd->makr+(SDnameLn-4), "...");
        }
        sd->dim[0] = sd->dim[1] = sd->dim[2] = .0;
        SDerrorDetail[0] = '\0';
        if ((geom = ezxml_child(wdb, "Width")) != NULL)
                sd->dim[0] = atof(ezxml_txt(geom)) *
                                to_meters(ezxml_attr(geom, "unit"));
        if ((geom = ezxml_child(wdb, "Height")) != NULL)
                sd->dim[1] = atof(ezxml_txt(geom)) *
                                to_meters(ezxml_attr(geom, "unit"));
        if ((geom = ezxml_child(wdb, "Thickness")) != NULL)
                sd->dim[2] = atof(ezxml_txt(geom)) *
                                to_meters(ezxml_attr(geom, "unit"));
        if ((sd->dim[0] < 0) | (sd->dim[1] < 0) | (sd->dim[2] < 0)) {
                if (!SDerrorDetail[0])
                        sprintf(SDerrorDetail, "Negative dimension in \"%s\"",
                                                sd->name);
                return SDEdata;
        }
        if ((geom = ezxml_child(wdb, "Geometry")) == NULL ||
                        (mgfstr = ezxml_txt(geom)) == NULL)
                return SDEnone;
        while (isspace(*mgfstr))
                ++mgfstr;
        if (!*mgfstr)
                return SDEnone;
        if ((fmt = ezxml_attr(geom, "format")) != NULL &&
                        strcasecmp(fmt, "MGF")) {
                sprintf(SDerrorDetail,
                        "Unrecognized geometry format '%s' in \"%s\"",
                                        fmt, sd->name);
                return SDEsupport;
        }
        cfact = to_meters(ezxml_attr(geom, "unit"));
        if (cfact <= 0)
                return SDEformat;
        sd->mgf = (char *)malloc(strlen(mgfstr)+32);
        if (sd->mgf == NULL) {
                strcpy(SDerrorDetail, "Out of memory in SDloadGeometry");
                return SDEmemory;
        }
        if (cfact < 0.99 || cfact > 1.01)
                sprintf(sd->mgf, "xf -s %.5f\n%s\nxf\n", cfact, mgfstr);
        else
                strcpy(sd->mgf, mgfstr);
        return SDEnone;
}

/* Load a BSDF struct from the given file (free first and keep name) */
SDError
SDloadFile(SDData *sd, const char *fname)
{
        SDError         lastErr;
        ezxml_t         fl, wtl;

        if ((sd == NULL) | (fname == NULL || !*fname))
                return SDEargument;
                                /* free old data, keeping name */
        SDfreeBSDF(sd);
                                /* parse XML file */
        fl = ezxml_parse_file(fname);
        if (fl == NULL) {
                sprintf(SDerrorDetail, "Cannot open BSDF \"%s\"", fname);
                return SDEfile;
        }
        if (ezxml_error(fl)[0]) {
                sprintf(SDerrorDetail, "BSDF \"%s\" %s", fname, ezxml_error(fl));
                ezxml_free(fl);
                return SDEformat;
        }
        if (strcmp(ezxml_name(fl), "WindowElement")) {
                sprintf(SDerrorDetail,
                        "BSDF \"%s\": top level node not 'WindowElement'",
                                sd->name);
                ezxml_free(fl);
                return SDEformat;
        }
        wtl = ezxml_child(ezxml_child(fl, "Optical"), "Layer");
        if (wtl == NULL) {
                sprintf(SDerrorDetail, "BSDF \"%s\": no optical layers'",
                                sd->name);
                ezxml_free(fl);
                return SDEformat;
        }
                                /* load geometry if present */
        lastErr = SDloadGeometry(sd, ezxml_child(wtl, "Material"));
        if (lastErr) {
                ezxml_free(fl);
                return lastErr;
        }
                                /* try loading variable resolution data */
        lastErr = SDloadTre(sd, wtl);
                                /* check our result */
        if (lastErr == SDEsupport)      /* try matrix BSDF if not tree data */
                lastErr = SDloadMtx(sd, wtl);
                
                                /* done with XML file */
        ezxml_free(fl);
        
        if (lastErr) {          /* was there a load error? */
                SDfreeBSDF(sd);
                return lastErr;
        }
                                /* remove any insignificant components */
        if (sd->rf != NULL && sd->rf->maxHemi <= .001) {
                SDfreeSpectralDF(sd->rf); sd->rf = NULL;
        }
        if (sd->rb != NULL && sd->rb->maxHemi <= .001) {
                SDfreeSpectralDF(sd->rb); sd->rb = NULL;
        }
        if (sd->tf != NULL && sd->tf->maxHemi <= .001) {
                SDfreeSpectralDF(sd->tf); sd->tf = NULL;
        }
        if (sd->tb != NULL && sd->tb->maxHemi <= .001) {
                SDfreeSpectralDF(sd->tb); sd->tb = NULL;
        }
                                /* return success */
        return SDEnone;
}

/* Allocate new spectral distribution function */
SDSpectralDF *
SDnewSpectralDF(int nc)
{
        SDSpectralDF    *df;
        
        if (nc <= 0) {
                strcpy(SDerrorDetail, "Zero component spectral DF request");
                return NULL;
        }
        df = (SDSpectralDF *)malloc(sizeof(SDSpectralDF) +
                                        (nc-1)*sizeof(SDComponent));
        if (df == NULL) {
                sprintf(SDerrorDetail,
                                "Cannot allocate %d component spectral DF", nc);
                return NULL;
        }
        df->minProjSA = .0;
        df->maxHemi = .0;
        df->ncomp = nc;
        memset(df->comp, 0, nc*sizeof(SDComponent));
        return df;
}

/* Add component(s) to spectral distribution function */
SDSpectralDF *
SDaddComponent(SDSpectralDF *odf, int nadd)
{
        SDSpectralDF    *df;

        if (odf == NULL)
                return SDnewSpectralDF(nadd);
        if (nadd <= 0)
                return odf;
        df = (SDSpectralDF *)realloc(odf, sizeof(SDSpectralDF) +
                                (odf->ncomp+nadd-1)*sizeof(SDComponent));
        if (df == NULL) {
                sprintf(SDerrorDetail,
                        "Cannot add %d component(s) to spectral DF", nadd);
                SDfreeSpectralDF(odf);
                return NULL;
        }
        memset(df->comp+df->ncomp, 0, nadd*sizeof(SDComponent));
        df->ncomp += nadd;
        return df;
}

/* Free cached cumulative distributions for BSDF component */
void
SDfreeCumulativeCache(SDSpectralDF *df)
{
        int     n;
        SDCDst  *cdp;

        if (df == NULL)
                return;
        for (n = df->ncomp; n-- > 0; )
                while ((cdp = df->comp[n].cdList) != NULL) {
                        df->comp[n].cdList = cdp->next;
                        free(cdp);
                }
}

/* Free a spectral distribution function */
void
SDfreeSpectralDF(SDSpectralDF *df)
{
        int     n;

        if (df == NULL)
                return;
        SDfreeCumulativeCache(df);
        for (n = df->ncomp; n-- > 0; )
                if (df->comp[n].dist != NULL)
                        (*df->comp[n].func->freeSC)(df->comp[n].dist);
        free(df);
}

/* Shorten file path to useable BSDF name, removing suffix */
void
SDclipName(char *res, const char *fname)
{
        const char      *cp, *dot = NULL;
        
        for (cp = fname; *cp; cp++)
                if (*cp == '.')
                        dot = cp;
        if ((dot == NULL) | (dot < fname+2))
                dot = cp;
        if (dot - fname >= SDnameLn)
                fname = dot - SDnameLn + 1;
        while (fname < dot)
                *res++ = *fname++;
        *res = '\0';
}

/* Initialize an unused BSDF struct (simply clears to zeroes) */
void
SDclearBSDF(SDData *sd, const char *fname)
{
        if (sd == NULL)
                return;
        memset(sd, 0, sizeof(SDData));
        if (fname == NULL)
                return;
        SDclipName(sd->name, fname);
}

/* Free data associated with BSDF struct */
void
SDfreeBSDF(SDData *sd)
{
        if (sd == NULL)
                return;
        if (sd->mgf != NULL) {
                free(sd->mgf);
                sd->mgf = NULL;
        }
        if (sd->rf != NULL) {
                SDfreeSpectralDF(sd->rf);
                sd->rf = NULL;
        }
        if (sd->rb != NULL) {
                SDfreeSpectralDF(sd->rb);
                sd->rb = NULL;
        }
        if (sd->tf != NULL) {
                SDfreeSpectralDF(sd->tf);
                sd->tf = NULL;
        }
        if (sd->tb != NULL) {
                SDfreeSpectralDF(sd->tb);
                sd->tb = NULL;
        }
        sd->rLambFront.cieY = .0;
        sd->rLambFront.spec.flags = 0;
        sd->rLambBack.cieY = .0;
        sd->rLambBack.spec.flags = 0;
        sd->tLamb.cieY = .0;
        sd->tLamb.spec.flags = 0;
}

/* Find writeable BSDF by name, or allocate new cache entry if absent */
SDData *
SDgetCache(const char *bname)
{
        struct SDCache_s        *sdl;
        char                    sdnam[SDnameLn];

        if (bname == NULL)
                return NULL;

        SDclipName(sdnam, bname);
        for (sdl = SDcacheList; sdl != NULL; sdl = sdl->next)
                if (!strcmp(sdl->bsdf.name, sdnam)) {
                        sdl->refcnt++;
                        return &sdl->bsdf;
                }

        sdl = (struct SDCache_s *)calloc(1, sizeof(struct SDCache_s));
        if (sdl == NULL)
                return NULL;

        strcpy(sdl->bsdf.name, sdnam);
        sdl->next = SDcacheList;
        SDcacheList = sdl;

        sdl->refcnt = 1;
        return &sdl->bsdf;
}

/* Get loaded BSDF from cache (or load and cache it on first call) */
/* Report any problem to stderr and return NULL on failure */
const SDData *
SDcacheFile(const char *fname)
{
        SDData          *sd;
        SDError         ec;
        
        if (fname == NULL || !*fname)
                return NULL;
        SDerrorDetail[0] = '\0';
        if ((sd = SDgetCache(fname)) == NULL) {
                SDreportEnglish(SDEmemory, stderr);
                return NULL;
        }
        if (!SDisLoaded(sd) && (ec = SDloadFile(sd, fname))) {
                SDreportEnglish(ec, stderr);
                SDfreeCache(sd);
                return NULL;
        }
        return sd;
}

/* Free a BSDF from our cache (clear all if NULL) */
void
SDfreeCache(const SDData *sd)
{
        struct SDCache_s        *sdl, *sdLast = NULL;

        if (sd == NULL) {               /* free entire list */
                while ((sdl = SDcacheList) != NULL) {
                        SDcacheList = sdl->next;
                        SDfreeBSDF(&sdl->bsdf);
                        free(sdl);
                }
                return;
        }
        for (sdl = SDcacheList; sdl != NULL; sdl = (sdLast=sdl)->next)
                if (&sdl->bsdf == sd)
                        break;
        if (sdl == NULL || (sdl->refcnt -= (sdl->refcnt > 0)))
                return;                 /* missing or still in use */
                                        /* keep unreferenced data? */
        if (SDisLoaded(sd) && SDretainSet) {
                if (SDretainSet == SDretainAll)
                        return;         /* keep everything */
                                        /* else free cumulative data */
                SDfreeCumulativeCache(sd->rf);
                SDfreeCumulativeCache(sd->rb);
                SDfreeCumulativeCache(sd->tf);
                SDfreeCumulativeCache(sd->tb);
                return;
        }
                                        /* remove from list and free */
        if (sdLast == NULL)
                SDcacheList = sdl->next;
        else
                sdLast->next = sdl->next;
        SDfreeBSDF(&sdl->bsdf);
        free(sdl);
}

/* Sample an individual BSDF component */
SDError
SDsampComponent(SDValue *sv, FVECT ioVec, double randX, SDComponent *sdc)
{
        float           coef[SDmaxCh];
        SDError         ec;
        FVECT           inVec;
        const SDCDst    *cd;
        double          d;
        int             n;
                                        /* check arguments */
        if ((sv == NULL) | (ioVec == NULL) | (sdc == NULL))
                return SDEargument;
                                        /* get cumulative distribution */
        VCOPY(inVec, ioVec);
        cd = (*sdc->func->getCDist)(inVec, sdc);
        if (cd == NULL)
                return SDEmemory;
        if (cd->cTotal <= 1e-6) {       /* anything to sample? */
                sv->spec = c_dfcolor;
                sv->cieY = .0;
                memset(ioVec, 0, 3*sizeof(double));
                return SDEnone;
        }
        sv->cieY = cd->cTotal;
                                        /* compute sample direction */
        ec = (*sdc->func->sampCDist)(ioVec, randX, cd);
        if (ec)
                return ec;
                                        /* get BSDF color */
        n = (*sdc->func->getBSDFs)(coef, ioVec, inVec, sdc);
        if (n <= 0) {
                strcpy(SDerrorDetail, "BSDF sample value error");
                return SDEinternal;
        }
        sv->spec = sdc->cspec[0];
        d = coef[0];
        while (--n) {
                c_cmix(&sv->spec, d, &sv->spec, coef[n], &sdc->cspec[n]);
                d += coef[n];
        }
                                        /* make sure everything is set */
        c_ccvt(&sv->spec, C_CSXY+C_CSSPEC);
        return SDEnone;
}

#define MS_MAXDIM       15

/* Convert 1-dimensional random variable to N-dimensional */
void
SDmultiSamp(double t[], int n, double randX)
{
        unsigned        nBits;
        double          scale;
        bitmask_t       ndx, coord[MS_MAXDIM];

        if (n <= 0)                     /* check corner cases */
                return;
        if (randX < 0) randX = 0;
        else if (randX >= 1.) randX = 0.999999999999999;
        if (n == 1) {
                t[0] = randX;
                return;
        }
        while (n > MS_MAXDIM)           /* punt for higher dimensions */
                t[--n] = rand()*(1./(RAND_MAX+.5));
        nBits = (8*sizeof(bitmask_t) - 1) / n;
        ndx = randX * (double)((bitmask_t)1 << (nBits*n));
                                        /* get coordinate on Hilbert curve */
        hilbert_i2c(n, nBits, ndx, coord);
                                        /* convert back to [0,1) range */
        scale = 1. / (double)((bitmask_t)1 << nBits);
        while (n--)
                t[n] = scale * ((double)coord[n] + rand()*(1./(RAND_MAX+.5)));
}

#undef MS_MAXDIM

/* Generate diffuse hemispherical sample */
static void
SDdiffuseSamp(FVECT outVec, int outFront, double randX)
{
                                        /* convert to position on hemisphere */
        SDmultiSamp(outVec, 2, randX);
        SDsquare2disk(outVec, outVec[0], outVec[1]);
        outVec[2] = 1. - outVec[0]*outVec[0] - outVec[1]*outVec[1];
        if (outVec[2] > 0)              /* a bit of paranoia */
                outVec[2] = sqrt(outVec[2]);
        if (!outFront)                  /* going out back? */
                outVec[2] = -outVec[2];
}

/* Query projected solid angle coverage for non-diffuse BSDF direction */
SDError
SDsizeBSDF(double *projSA, const FVECT v1, const RREAL *v2,
                                int qflags, const SDData *sd)
{
        SDSpectralDF    *rdf, *tdf;
        SDError         ec;
        int             i;
                                        /* check arguments */
        if ((projSA == NULL) | (v1 == NULL) | (sd == NULL))
                return SDEargument;
                                        /* initialize extrema */
        switch (qflags) {
        case SDqueryMax:
                projSA[0] = .0;
                break;
        case SDqueryMin+SDqueryMax:
                projSA[1] = .0;
                /* fall through */
        case SDqueryMin:
                projSA[0] = 10.;
                break;
        case 0:
                return SDEargument;
        }
        if (v1[2] > 0) {                /* front surface query? */
                rdf = sd->rf;
                tdf = (sd->tf != NULL) ? sd->tf : sd->tb;
        } else {
                rdf = sd->rb;
                tdf = (sd->tb != NULL) ? sd->tb : sd->tf;
        }
        if (v2 != NULL)                 /* bidirectional? */
                if (v1[2] > 0 ^ v2[2] > 0)
                        rdf = NULL;
                else
                        tdf = NULL;
        ec = SDEdata;                   /* run through components */
        for (i = (rdf==NULL) ? 0 : rdf->ncomp; i--; ) {
                ec = (*rdf->comp[i].func->queryProjSA)(projSA, v1, v2,
                                                qflags, &rdf->comp[i]);
                if (ec)
                        return ec;
        }
        for (i = (tdf==NULL) ? 0 : tdf->ncomp; i--; ) {
                ec = (*tdf->comp[i].func->queryProjSA)(projSA, v1, v2,
                                                qflags, &tdf->comp[i]);
                if (ec)
                        return ec;
        }
        if (ec) {                       /* all diffuse? */
                projSA[0] = M_PI;
                if (qflags == SDqueryMin+SDqueryMax)
                        projSA[1] = M_PI;
        }
        return SDEnone;
}

/* Return BSDF for the given incident and scattered ray vectors */
SDError
SDevalBSDF(SDValue *sv, const FVECT outVec, const FVECT inVec, const SDData *sd)
{
        int             inFront, outFront;
        SDSpectralDF    *sdf;
        float           coef[SDmaxCh];
        int             nch, i;
                                        /* check arguments */
        if ((sv == NULL) | (outVec == NULL) | (inVec == NULL) | (sd == NULL))
                return SDEargument;
                                        /* whose side are we on? */
        inFront = (inVec[2] > 0);
        outFront = (outVec[2] > 0);
                                        /* start with diffuse portion */
        if (inFront & outFront) {
                *sv = sd->rLambFront;
                sdf = sd->rf;
        } else if (!(inFront | outFront)) {
                *sv = sd->rLambBack;
                sdf = sd->rb;
        } else if (inFront) {
                *sv = sd->tLamb;
                sdf = (sd->tf != NULL) ? sd->tf : sd->tb;
        } else /* inBack */ {
                *sv = sd->tLamb;
                sdf = (sd->tb != NULL) ? sd->tb : sd->tf;
        }
        sv->cieY *= 1./M_PI;
                                        /* add non-diffuse components */
        i = (sdf != NULL) ? sdf->ncomp : 0;
        while (i-- > 0) {
                nch = (*sdf->comp[i].func->getBSDFs)(coef, outVec, inVec,
                                                        &sdf->comp[i]);
                while (nch-- > 0) {
                        c_cmix(&sv->spec, sv->cieY, &sv->spec,
                                        coef[nch], &sdf->comp[i].cspec[nch]);
                        sv->cieY += coef[nch];
                }
        }
                                        /* make sure everything is set */
        c_ccvt(&sv->spec, C_CSXY+C_CSSPEC);
        return SDEnone;
}

/* Compute directional hemispherical scattering at this incident angle */
double
SDdirectHemi(const FVECT inVec, int sflags, const SDData *sd)
{
        double          hsum;
        SDSpectralDF    *rdf, *tdf;
        const SDCDst    *cd;
        int             i;
                                        /* check arguments */
        if ((inVec == NULL) | (sd == NULL))
                return .0;
                                        /* gather diffuse components */
        if (inVec[2] > 0) {
                hsum = sd->rLambFront.cieY;
                rdf = sd->rf;
                tdf = (sd->tf != NULL) ? sd->tf : sd->tb;
        } else /* !inFront */ {
                hsum = sd->rLambBack.cieY;
                rdf = sd->rb;
                tdf = (sd->tb != NULL) ? sd->tb : sd->tf;
        }
        if ((sflags & SDsampDf+SDsampR) != SDsampDf+SDsampR)
                hsum = .0;
        if ((sflags & SDsampDf+SDsampT) == SDsampDf+SDsampT)
                hsum += sd->tLamb.cieY;
                                        /* gather non-diffuse components */
        i = (((sflags & SDsampSp+SDsampR) == SDsampSp+SDsampR) &
                        (rdf != NULL)) ? rdf->ncomp : 0;
        while (i-- > 0) {               /* non-diffuse reflection */
                cd = (*rdf->comp[i].func->getCDist)(inVec, &rdf->comp[i]);
                if (cd != NULL)
                        hsum += cd->cTotal;
        }
        i = (((sflags & SDsampSp+SDsampT) == SDsampSp+SDsampT) &
                        (tdf != NULL)) ? tdf->ncomp : 0;
        while (i-- > 0) {               /* non-diffuse transmission */
                cd = (*tdf->comp[i].func->getCDist)(inVec, &tdf->comp[i]);
                if (cd != NULL)
                        hsum += cd->cTotal;
        }
        return hsum;
}

/* Sample BSDF direction based on the given random variable */
SDError
SDsampBSDF(SDValue *sv, FVECT ioVec, double randX, int sflags, const SDData *sd)
{
        SDError         ec;
        FVECT           inVec;
        int             inFront;
        SDSpectralDF    *rdf, *tdf;
        double          rdiff;
        float           coef[SDmaxCh];
        int             i, j, n, nr;
        SDComponent     *sdc;
        const SDCDst    **cdarr = NULL;
                                        /* check arguments */
        if ((sv == NULL) | (ioVec == NULL) | (sd == NULL) |
                        (randX < 0) | (randX >= 1.))
                return SDEargument;
                                        /* whose side are we on? */
        VCOPY(inVec, ioVec);
        inFront = (inVec[2] > 0);
                                        /* remember diffuse portions */
        if (inFront) {
                *sv = sd->rLambFront;
                rdf = sd->rf;
                tdf = (sd->tf != NULL) ? sd->tf : sd->tb;
        } else /* !inFront */ {
                *sv = sd->rLambBack;
                rdf = sd->rb;
                tdf = (sd->tb != NULL) ? sd->tb : sd->tf;
        }
        if ((sflags & SDsampDf+SDsampR) != SDsampDf+SDsampR)
                sv->cieY = .0;
        rdiff = sv->cieY;
        if ((sflags & SDsampDf+SDsampT) == SDsampDf+SDsampT)
                sv->cieY += sd->tLamb.cieY;
                                        /* gather non-diffuse components */
        i = nr = (((sflags & SDsampSp+SDsampR) == SDsampSp+SDsampR) &
                        (rdf != NULL)) ? rdf->ncomp : 0;
        j = (((sflags & SDsampSp+SDsampT) == SDsampSp+SDsampT) &
                        (tdf != NULL)) ? tdf->ncomp : 0;
        n = i + j;
        if (n > 0 && (cdarr = (const SDCDst **)malloc(n*sizeof(SDCDst *))) == NULL)
                return SDEmemory;
        while (j-- > 0) {               /* non-diffuse transmission */
                cdarr[i+j] = (*tdf->comp[j].func->getCDist)(inVec, &tdf->comp[j]);
                if (cdarr[i+j] == NULL) {
                        free(cdarr);
                        return SDEmemory;
                }
                sv->cieY += cdarr[i+j]->cTotal;
        }
        while (i-- > 0) {               /* non-diffuse reflection */
                cdarr[i] = (*rdf->comp[i].func->getCDist)(inVec, &rdf->comp[i]);
                if (cdarr[i] == NULL) {
                        free(cdarr);
                        return SDEmemory;
                }
                sv->cieY += cdarr[i]->cTotal;
        }
        if (sv->cieY <= 1e-6) {         /* anything to sample? */
                sv->cieY = .0;
                memset(ioVec, 0, 3*sizeof(double));
                return SDEnone;
        }
                                        /* scale random variable */
        randX *= sv->cieY;
                                        /* diffuse reflection? */
        if (randX < rdiff) {
                SDdiffuseSamp(ioVec, inFront, randX/rdiff);
                goto done;
        }
        randX -= rdiff;
                                        /* diffuse transmission? */
        if ((sflags & SDsampDf+SDsampT) == SDsampDf+SDsampT) {
                if (randX < sd->tLamb.cieY) {
                        sv->spec = sd->tLamb.spec;
                        SDdiffuseSamp(ioVec, !inFront, randX/sd->tLamb.cieY);
                        goto done;
                }
                randX -= sd->tLamb.cieY;
        }
                                        /* else one of cumulative dist. */
        for (i = 0; i < n && randX < cdarr[i]->cTotal; i++)
                randX -= cdarr[i]->cTotal;
        if (i >= n)
                return SDEinternal;
                                        /* compute sample direction */
        sdc = (i < nr) ? &rdf->comp[i] : &tdf->comp[i-nr];
        ec = (*sdc->func->sampCDist)(ioVec, randX/cdarr[i]->cTotal, cdarr[i]);
        if (ec)
                return ec;
                                        /* compute color */
        j = (*sdc->func->getBSDFs)(coef, ioVec, inVec, sdc);
        if (j <= 0) {
                sprintf(SDerrorDetail, "BSDF \"%s\" sampling value error",
                                sd->name);
                return SDEinternal;
        }
        sv->spec = sdc->cspec[0];
        rdiff = coef[0];
        while (--j) {
                c_cmix(&sv->spec, rdiff, &sv->spec, coef[j], &sdc->cspec[j]);
                rdiff += coef[j];
        }
done:
        if (cdarr != NULL)
                free(cdarr);
                                        /* make sure everything is set */
        c_ccvt(&sv->spec, C_CSXY+C_CSSPEC);
        return SDEnone;
}

/* Compute World->BSDF transform from surface normal and up (Y) vector */
SDError 
SDcompXform(RREAL vMtx[3][3], const FVECT sNrm, const FVECT uVec)
{
        if ((vMtx == NULL) | (sNrm == NULL) | (uVec == NULL))
                return SDEargument;
        VCOPY(vMtx[2], sNrm);
        if (normalize(vMtx[2]) == 0)
                return SDEargument;
        fcross(vMtx[0], uVec, vMtx[2]);
        if (normalize(vMtx[0]) == 0)
                return SDEargument;
        fcross(vMtx[1], vMtx[2], vMtx[0]);
        return SDEnone;
}

/* Compute inverse transform */
SDError 
SDinvXform(RREAL iMtx[3][3], RREAL vMtx[3][3])
{
        RREAL   mTmp[3][3];
        double  d;

        if ((iMtx == NULL) | (vMtx == NULL))
                return SDEargument;
                                        /* compute determinant */
        mTmp[0][0] = vMtx[2][2]*vMtx[1][1] - vMtx[2][1]*vMtx[1][2];
        mTmp[0][1] = vMtx[2][1]*vMtx[0][2] - vMtx[2][2]*vMtx[0][1];
        mTmp[0][2] = vMtx[1][2]*vMtx[0][1] - vMtx[1][1]*vMtx[0][2];
        d = vMtx[0][0]*mTmp[0][0] + vMtx[1][0]*mTmp[0][1] + vMtx[2][0]*mTmp[0][2];
        if (d == 0) {
                strcpy(SDerrorDetail, "Zero determinant in matrix inversion");
                return SDEargument;
        }
        d = 1./d;                       /* invert matrix */
        mTmp[0][0] *= d; mTmp[0][1] *= d; mTmp[0][2] *= d;
        mTmp[1][0] = d*(vMtx[2][0]*vMtx[1][2] - vMtx[2][2]*vMtx[1][0]);
        mTmp[1][1] = d*(vMtx[2][2]*vMtx[0][0] - vMtx[2][0]*vMtx[0][2]);
        mTmp[1][2] = d*(vMtx[1][0]*vMtx[0][2] - vMtx[1][2]*vMtx[0][0]);
        mTmp[2][0] = d*(vMtx[2][1]*vMtx[1][0] - vMtx[2][0]*vMtx[1][1]);
        mTmp[2][1] = d*(vMtx[2][0]*vMtx[0][1] - vMtx[2][1]*vMtx[0][0]);
        mTmp[2][2] = d*(vMtx[1][1]*vMtx[0][0] - vMtx[1][0]*vMtx[0][1]);
        memcpy(iMtx, mTmp, sizeof(mTmp));
        return SDEnone;
}

/* Transform and normalize direction (column) vector */
SDError
SDmapDir(FVECT resVec, RREAL vMtx[3][3], const FVECT inpVec)
{
        FVECT   vTmp;

        if ((resVec == NULL) | (inpVec == NULL))
                return SDEargument;
        if (vMtx == NULL) {             /* assume they just want to normalize */
                if (resVec != inpVec)
                        VCOPY(resVec, inpVec);
                return (normalize(resVec) > 0) ? SDEnone : SDEargument;
        }
        vTmp[0] = DOT(vMtx[0], inpVec);
        vTmp[1] = DOT(vMtx[1], inpVec);
        vTmp[2] = DOT(vMtx[2], inpVec);
        if (normalize(vTmp) == 0)
                return SDEargument;
        VCOPY(resVec, vTmp);
        return SDEnone;
}

/*################################################################*/
/*######### DEPRECATED ROUTINES AWAITING PERMANENT REMOVAL #######*/

/*
 * Routines for handling BSDF data
 */

#include "standard.h"
#include "paths.h"

#define MAXLATS         46              /* maximum number of latitudes */

/* BSDF angle specification */
typedef struct {
        char    name[64];               /* basis name */
        int     nangles;                /* total number of directions */
        struct {
                float   tmin;                   /* starting theta */
                short   nphis;                  /* number of phis (0 term) */
        }       lat[MAXLATS+1];         /* latitudes */
} ANGLE_BASIS;

#define MAXABASES       7               /* limit on defined bases */

static ANGLE_BASIS      abase_list[MAXABASES] = {
        {
                "LBNL/Klems Full", 145,
                { {-5., 1},
                {5., 8},
                {15., 16},
                {25., 20},
                {35., 24},
                {45., 24},
                {55., 24},
                {65., 16},
                {75., 12},
                {90., 0} }
        }, {
                "LBNL/Klems Half", 73,
                { {-6.5, 1},
                {6.5, 8},
                {19.5, 12},
                {32.5, 16},
                {46.5, 20},
                {61.5, 12},
                {76.5, 4},
                {90., 0} }
        }, {
                "LBNL/Klems Quarter", 41,
                { {-9., 1},
                {9., 8},
                {27., 12},
                {46., 12},
                {66., 8},
                {90., 0} }
        }
};

static int      nabases = 3;    /* current number of defined bases */

#define  FEQ(a,b)       ((a)-(b) <= 1e-6 && (b)-(a) <= 1e-6)

static int
fequal(double a, double b)
{
        if (b != 0)
                a = a/b - 1.;
        return((a <= 1e-6) & (a >= -1e-6));
}

/* Returns the name of the given tag */
#ifdef ezxml_name
#undef ezxml_name
static char *
ezxml_name(ezxml_t xml)
{
        if (xml == NULL)
                return(NULL);
        return(xml->name);
}
#endif

/* Returns the given tag's character content or empty string if none */
#ifdef ezxml_txt
#undef ezxml_txt
static char *
ezxml_txt(ezxml_t xml)
{
        if (xml == NULL)
                return("");
        return(xml->txt);
}
#endif


static int
ab_getvec(              /* get vector for this angle basis index */
        FVECT v,
        int ndx,
        void *p
)
{
        ANGLE_BASIS  *ab = (ANGLE_BASIS *)p;
        int     li;
        double  pol, azi, d;
        
        if ((ndx < 0) | (ndx >= ab->nangles))
                return(0);
        for (li = 0; ndx >= ab->lat[li].nphis; li++)
                ndx -= ab->lat[li].nphis;
        pol = PI/180.*0.5*(ab->lat[li].tmin + ab->lat[li+1].tmin);
        azi = 2.*PI*ndx/ab->lat[li].nphis;
        v[2] = d = cos(pol);
        d = sqrt(1. - d*d);     /* sin(pol) */
        v[0] = cos(azi)*d;
        v[1] = sin(azi)*d;
        return(1);
}


static int
ab_getndx(              /* get index corresponding to the given vector */
        FVECT v,
        void *p
)
{
        ANGLE_BASIS  *ab = (ANGLE_BASIS *)p;
        int     li, ndx;
        double  pol, azi;

        if ((v[2] < -1.0) | (v[2] > 1.0))
                return(-1);
        pol = 180.0/PI*acos(v[2]);
        azi = 180.0/PI*atan2(v[1], v[0]);
        if (azi < 0.0) azi += 360.0;
        for (li = 1; ab->lat[li].tmin <= pol; li++)
                if (!ab->lat[li].nphis)
                        return(-1);
        --li;
        ndx = (int)((1./360.)*azi*ab->lat[li].nphis + 0.5);
        if (ndx >= ab->lat[li].nphis) ndx = 0;
        while (li--)
                ndx += ab->lat[li].nphis;
        return(ndx);
}


static double
ab_getohm(              /* get solid angle for this angle basis index */
        int ndx,
        void *p
)
{
        ANGLE_BASIS  *ab = (ANGLE_BASIS *)p;
        int     li;
        double  theta, theta1;
        
        if ((ndx < 0) | (ndx >= ab->nangles))
                return(0);
        for (li = 0; ndx >= ab->lat[li].nphis; li++)
                ndx -= ab->lat[li].nphis;
        theta1 = PI/180. * ab->lat[li+1].tmin;
        if (ab->lat[li].nphis == 1) {           /* special case */
                if (ab->lat[li].tmin > FTINY)
                        error(USER, "unsupported BSDF coordinate system");
                return(2.*PI*(1. - cos(theta1)));
        }
        theta = PI/180. * ab->lat[li].tmin;
        return(2.*PI*(cos(theta) - cos(theta1))/(double)ab->lat[li].nphis);
}


static int
ab_getvecR(             /* get reverse vector for this angle basis index */
        FVECT v,
        int ndx,
        void *p
)
{
        if (!ab_getvec(v, ndx, p))
                return(0);

        v[0] = -v[0];
        v[1] = -v[1];
        v[2] = -v[2];

        return(1);
}


static int
ab_getndxR(             /* get index corresponding to the reverse vector */
        FVECT v,
        void *p
)
{
        FVECT  v2;
        
        v2[0] = -v[0];
        v2[1] = -v[1];
        v2[2] = -v[2];

        return ab_getndx(v2, p);
}


static void
load_angle_basis(       /* load custom BSDF angle basis */
        ezxml_t wab
)
{
        char    *abname = ezxml_txt(ezxml_child(wab, "AngleBasisName"));
        ezxml_t wbb;
        int     i;
        
        if (!abname || !*abname)
                return;
        for (i = nabases; i--; )
                if (!strcasecmp(abname, abase_list[i].name))
                        return;         /* assume it's the same */
        if (nabases >= MAXABASES)
                error(INTERNAL, "too many angle bases");
        strcpy(abase_list[nabases].name, abname);
        abase_list[nabases].nangles = 0;
        for (i = 0, wbb = ezxml_child(wab, "AngleBasisBlock");
                        wbb != NULL; i++, wbb = wbb->next) {
                if (i >= MAXLATS)
                        error(INTERNAL, "too many latitudes in custom basis");
                abase_list[nabases].lat[i+1].tmin = atof(ezxml_txt(
                                ezxml_child(ezxml_child(wbb,
                                        "ThetaBounds"), "UpperTheta")));
                if (!i)
                        abase_list[nabases].lat[i].tmin =
                                        -abase_list[nabases].lat[i+1].tmin;
                else if (!fequal(atof(ezxml_txt(ezxml_child(ezxml_child(wbb,
                                        "ThetaBounds"), "LowerTheta"))),
                                abase_list[nabases].lat[i].tmin))
                        error(WARNING, "theta values disagree in custom basis");
                abase_list[nabases].nangles +=
                        abase_list[nabases].lat[i].nphis =
                                atoi(ezxml_txt(ezxml_child(wbb, "nPhis")));
        }
        abase_list[nabases++].lat[i].nphis = 0;
}


static void
load_geometry(          /* load geometric dimensions and description (if any) */
        struct BSDF_data *dp,
        ezxml_t wdb
)
{
        ezxml_t         geom;
        double          cfact;
        const char      *fmt, *mgfstr;

        dp->dim[0] = dp->dim[1] = dp->dim[2] = 0;
        dp->mgf = NULL;
        if ((geom = ezxml_child(wdb, "Width")) != NULL)
                dp->dim[0] = atof(ezxml_txt(geom)) *
                                to_meters(ezxml_attr(geom, "unit"));
        if ((geom = ezxml_child(wdb, "Height")) != NULL)
                dp->dim[1] = atof(ezxml_txt(geom)) *
                                to_meters(ezxml_attr(geom, "unit"));
        if ((geom = ezxml_child(wdb, "Thickness")) != NULL)
                dp->dim[2] = atof(ezxml_txt(geom)) *
                                to_meters(ezxml_attr(geom, "unit"));
        if ((geom = ezxml_child(wdb, "Geometry")) == NULL ||
                        (mgfstr = ezxml_txt(geom)) == NULL)
                return;
        if ((fmt = ezxml_attr(geom, "format")) != NULL &&
                        strcasecmp(fmt, "MGF")) {
                sprintf(errmsg, "unrecognized geometry format '%s'", fmt);
                error(WARNING, errmsg);
                return;
        }
        cfact = to_meters(ezxml_attr(geom, "unit"));
        dp->mgf = (char *)malloc(strlen(mgfstr)+32);
        if (dp->mgf == NULL)
                error(SYSTEM, "out of memory in load_geometry");
        if (cfact < 0.99 || cfact > 1.01)
                sprintf(dp->mgf, "xf -s %.5f\n%s\nxf\n", cfact, mgfstr);
        else
                strcpy(dp->mgf, mgfstr);
}


static void
load_bsdf_data(         /* load BSDF distribution for this wavelength */
        struct BSDF_data *dp,
        ezxml_t wdb
)
{
        char  *cbasis = ezxml_txt(ezxml_child(wdb,"ColumnAngleBasis"));
        char  *rbasis = ezxml_txt(ezxml_child(wdb,"RowAngleBasis"));
        char  *sdata;
        int  i;
        
        if ((!cbasis || !*cbasis) | (!rbasis || !*rbasis)) {
                error(WARNING, "missing column/row basis for BSDF");
                return;
        }
        for (i = nabases; i--; )
                if (!strcasecmp(cbasis, abase_list[i].name)) {
                        dp->ninc = abase_list[i].nangles;
                        dp->ib_priv = (void *)&abase_list[i];
                        dp->ib_vec = ab_getvecR;
                        dp->ib_ndx = ab_getndxR;
                        dp->ib_ohm = ab_getohm;
                        break;
                }
        if (i < 0) {
                sprintf(errmsg, "undefined ColumnAngleBasis '%s'", cbasis);
                error(WARNING, errmsg);
                return;
        }
        for (i = nabases; i--; )
                if (!strcasecmp(rbasis, abase_list[i].name)) {
                        dp->nout = abase_list[i].nangles;
                        dp->ob_priv = (void *)&abase_list[i];
                        dp->ob_vec = ab_getvec;
                        dp->ob_ndx = ab_getndx;
                        dp->ob_ohm = ab_getohm;
                        break;
                }
        if (i < 0) {
                sprintf(errmsg, "undefined RowAngleBasis '%s'", rbasis);
                error(WARNING, errmsg);
                return;
        }
                                /* read BSDF data */
        sdata  = ezxml_txt(ezxml_child(wdb,"ScatteringData"));
        if (!sdata || !*sdata) {
                error(WARNING, "missing BSDF ScatteringData");
                return;
        }
        dp->bsdf = (float *)malloc(sizeof(float)*dp->ninc*dp->nout);
        if (dp->bsdf == NULL)
                error(SYSTEM, "out of memory in load_bsdf_data");
        for (i = 0; i < dp->ninc*dp->nout; i++) {
                char  *sdnext = fskip(sdata);
                if (sdnext == NULL) {
                        error(WARNING, "bad/missing BSDF ScatteringData");
                        free(dp->bsdf); dp->bsdf = NULL;
                        return;
                }
                while (*sdnext && isspace(*sdnext))
                        sdnext++;
                if (*sdnext == ',') sdnext++;
                dp->bsdf[i] = atof(sdata);
                sdata = sdnext;
        }
        while (isspace(*sdata))
                sdata++;
        if (*sdata) {
                sprintf(errmsg, "%d extra characters after BSDF ScatteringData",
                                (int)strlen(sdata));
                error(WARNING, errmsg);
        }
}


static int
check_bsdf_data(        /* check that BSDF data is sane */
        struct BSDF_data *dp
)
{
        double          *omega_iarr, *omega_oarr;
        double          dom, hemi_total, full_total;
        int             nneg;
        FVECT           v;
        int             i, o;

        if (dp == NULL || dp->bsdf == NULL)
                return(0);
        omega_iarr = (double *)calloc(dp->ninc, sizeof(double));
        omega_oarr = (double *)calloc(dp->nout, sizeof(double));
        if ((omega_iarr == NULL) | (omega_oarr == NULL))
                error(SYSTEM, "out of memory in check_bsdf_data");
                                        /* incoming projected solid angles */
        hemi_total = .0;
        for (i = dp->ninc; i--; ) {
                dom = getBSDF_incohm(dp,i);
                if (dom <= 0) {
                        error(WARNING, "zero/negative incoming solid angle");
                        continue;
                }
                if (!getBSDF_incvec(v,dp,i) || v[2] > FTINY) {
                        error(WARNING, "illegal incoming BSDF direction");
                        free(omega_iarr); free(omega_oarr);
                        return(0);
                }
                hemi_total += omega_iarr[i] = dom * -v[2];
        }
        if ((hemi_total > 1.02*PI) | (hemi_total < 0.98*PI)) {
                sprintf(errmsg, "incoming BSDF hemisphere off by %.1f%%",
                                100.*(hemi_total/PI - 1.));
                error(WARNING, errmsg);
        }
        dom = PI / hemi_total;          /* fix normalization */
        for (i = dp->ninc; i--; )
                omega_iarr[i] *= dom;
                                        /* outgoing projected solid angles */
        hemi_total = .0;
        for (o = dp->nout; o--; ) {
                dom = getBSDF_outohm(dp,o);
                if (dom <= 0) {
                        error(WARNING, "zero/negative outgoing solid angle");
                        continue;
                }
                if (!getBSDF_outvec(v,dp,o) || v[2] < -FTINY) {
                        error(WARNING, "illegal outgoing BSDF direction");
                        free(omega_iarr); free(omega_oarr);
                        return(0);
                }
                hemi_total += omega_oarr[o] = dom * v[2];
        }
        if ((hemi_total > 1.02*PI) | (hemi_total < 0.98*PI)) {
                sprintf(errmsg, "outgoing BSDF hemisphere off by %.1f%%",
                                100.*(hemi_total/PI - 1.));
                error(WARNING, errmsg);
        }
        dom = PI / hemi_total;          /* fix normalization */
        for (o = dp->nout; o--; )
                omega_oarr[o] *= dom;
        nneg = 0;                       /* check outgoing totals */
        for (i = 0; i < dp->ninc; i++) {
                hemi_total = .0;
                for (o = dp->nout; o--; ) {
                        double  f = BSDF_value(dp,i,o);
                        if (f >= 0)
                                hemi_total += f*omega_oarr[o];
                        else {
                                nneg += (f < -FTINY);
                                BSDF_value(dp,i,o) = .0f;
                        }
                }
                if (hemi_total > 1.01) {
                        sprintf(errmsg,
                        "incoming BSDF direction %d passes %.1f%% of light",
                                        i, 100.*hemi_total);
                        error(WARNING, errmsg);
                }
        }
        if (nneg) {
                sprintf(errmsg, "%d negative BSDF values (ignored)", nneg);
                error(WARNING, errmsg);
        }
        full_total = .0;                /* reverse roles and check again */
        for (o = 0; o < dp->nout; o++) {
                hemi_total = .0;
                for (i = dp->ninc; i--; )
                        hemi_total += BSDF_value(dp,i,o) * omega_iarr[i];

                if (hemi_total > 1.01) {
                        sprintf(errmsg,
                        "outgoing BSDF direction %d collects %.1f%% of light",
                                        o, 100.*hemi_total);
                        error(WARNING, errmsg);
                }
                full_total += hemi_total*omega_oarr[o];
        }
        full_total /= PI;
        if (full_total > 1.00001) {
                sprintf(errmsg, "BSDF transfers %.4f%% of light",
                                100.*full_total);
                error(WARNING, errmsg);
        }
        free(omega_iarr); free(omega_oarr);
        return(1);
}


struct BSDF_data *
load_BSDF(              /* load BSDF data from file */
        char *fname
)
{
        char                    *path;
        ezxml_t                 fl, wtl, wld, wdb;
        struct BSDF_data        *dp;
        
        path = getpath(fname, getrlibpath(), R_OK);
        if (path == NULL) {
                sprintf(errmsg, "cannot find BSDF file \"%s\"", fname);
                error(WARNING, errmsg);
                return(NULL);
        }
        fl = ezxml_parse_file(path);
        if (fl == NULL) {
                sprintf(errmsg, "cannot open BSDF \"%s\"", path);
                error(WARNING, errmsg);
                return(NULL);
        }
        if (ezxml_error(fl)[0]) {
                sprintf(errmsg, "BSDF \"%s\" %s", path, ezxml_error(fl));
                error(WARNING, errmsg);
                ezxml_free(fl);
                return(NULL);
        }
        if (strcmp(ezxml_name(fl), "WindowElement")) {
                sprintf(errmsg,
                        "BSDF \"%s\": top level node not 'WindowElement'",
                                path);
                error(WARNING, errmsg);
                ezxml_free(fl);
                return(NULL);
        }
        wtl = ezxml_child(ezxml_child(fl, "Optical"), "Layer");
        if (strcasecmp(ezxml_txt(ezxml_child(ezxml_child(wtl,
                        "DataDefinition"), "IncidentDataStructure")),
                        "Columns")) {
                sprintf(errmsg,
                        "BSDF \"%s\": unsupported IncidentDataStructure",
                                path);
                error(WARNING, errmsg);
                ezxml_free(fl);
                return(NULL);
        }
        for (wld = ezxml_child(ezxml_child(wtl,
                                "DataDefinition"), "AngleBasis");
                        wld != NULL; wld = wld->next)
                load_angle_basis(wld);
        dp = (struct BSDF_data *)calloc(1, sizeof(struct BSDF_data));
        load_geometry(dp, ezxml_child(wtl, "Material"));
        for (wld = ezxml_child(wtl, "WavelengthData");
                                wld != NULL; wld = wld->next) {
                if (strcasecmp(ezxml_txt(ezxml_child(wld,"Wavelength")),
                                "Visible"))
                        continue;
                for (wdb = ezxml_child(wld, "WavelengthDataBlock");
                                wdb != NULL; wdb = wdb->next)
                        if (!strcasecmp(ezxml_txt(ezxml_child(wdb,
                                        "WavelengthDataDirection")),
                                        "Transmission Front"))
                                break;
                if (wdb != NULL) {              /* load front BTDF */
                        load_bsdf_data(dp, wdb);
                        break;                  /* ignore the rest */
                }
        }
        ezxml_free(fl);                         /* done with XML file */
        if (!check_bsdf_data(dp)) {
                sprintf(errmsg, "bad/missing BTDF data in \"%s\"", path);
                error(WARNING, errmsg);
                free_BSDF(dp);
                dp = NULL;
        }
        return(dp);
}


void
free_BSDF(              /* free BSDF data structure */
        struct BSDF_data *b
)
{
        if (b == NULL)
                return;
        if (b->mgf != NULL)
                free(b->mgf);
        if (b->bsdf != NULL)
                free(b->bsdf);
        free(b);
}


int
r_BSDF_incvec(          /* compute random input vector at given location */
        FVECT v,
        struct BSDF_data *b,
        int i,
        double rv,
        MAT4 xm
)
{
        FVECT   pert;
        double  rad;
        int     j;
        
        if (!getBSDF_incvec(v, b, i))
                return(0);
        rad = sqrt(getBSDF_incohm(b, i) / PI);
        SDmultiSamp(pert, 3, rv);
        for (j = 0; j < 3; j++)
                v[j] += rad*(2.*pert[j] - 1.);
        if (xm != NULL)
                multv3(v, v, xm);
        return(normalize(v) != 0.0);
}


int
r_BSDF_outvec(          /* compute random output vector at given location */
        FVECT v,
        struct BSDF_data *b,
        int o,
        double rv,
        MAT4 xm
)
{
        FVECT   pert;
        double  rad;
        int     j;
        
        if (!getBSDF_outvec(v, b, o))
                return(0);
        rad = sqrt(getBSDF_outohm(b, o) / PI);
        SDmultiSamp(pert, 3, rv);
        for (j = 0; j < 3; j++)
                v[j] += rad*(2.*pert[j] - 1.);
        if (xm != NULL)
                multv3(v, v, xm);
        return(normalize(v) != 0.0);
}


static int
addrot(                 /* compute rotation (x,y,z) => (xp,yp,zp) */
        char *xfarg[],
        FVECT xp,
        FVECT yp,
        FVECT zp
)
{
        static char     bufs[3][16];
        int     bn = 0;
        char    **xfp = xfarg;
        double  theta;

        if (yp[2]*yp[2] + zp[2]*zp[2] < 2.*FTINY*FTINY) {
                /* Special case for X' along Z-axis */
                theta = -atan2(yp[0], yp[1]);
                *xfp++ = "-ry";
                *xfp++ = xp[2] < 0.0 ? "90" : "-90";
                *xfp++ = "-rz";
                sprintf(bufs[bn], "%f", theta*(180./PI));
                *xfp++ = bufs[bn++];
                return(xfp - xfarg);
        }
        theta = atan2(yp[2], zp[2]);
        if (!FEQ(theta,0.0)) {
                *xfp++ = "-rx";
                sprintf(bufs[bn], "%f", theta*(180./PI));
                *xfp++ = bufs[bn++];
        }
        theta = asin(-xp[2]);
        if (!FEQ(theta,0.0)) {
                *xfp++ = "-ry";
                sprintf(bufs[bn], " %f", theta*(180./PI));
                *xfp++ = bufs[bn++];
        }
        theta = atan2(xp[1], xp[0]);
        if (!FEQ(theta,0.0)) {
                *xfp++ = "-rz";
                sprintf(bufs[bn], "%f", theta*(180./PI));
                *xfp++ = bufs[bn++];
        }
        *xfp = NULL;
        return(xfp - xfarg);
}


int
getBSDF_xfm(            /* compute BSDF orient. -> world orient. transform */
        MAT4 xm,
        FVECT nrm,
        UpDir ud,
        char *xfbuf
)
{
        char    *xfargs[7];
        XF      myxf;
        FVECT   updir, xdest, ydest;
        int     i;

        updir[0] = updir[1] = updir[2] = 0.;
        switch (ud) {
        case UDzneg:
                updir[2] = -1.;
                break;
        case UDyneg:
                updir[1] = -1.;
                break;
        case UDxneg:
                updir[0] = -1.;
                break;
        case UDxpos:
                updir[0] = 1.;
                break;
        case UDypos:
                updir[1] = 1.;
                break;
        case UDzpos:
                updir[2] = 1.;
                break;
        case UDunknown:
                return(0);
        }
        fcross(xdest, updir, nrm);
        if (normalize(xdest) == 0.0)
                return(0);
        fcross(ydest, nrm, xdest);
        xf(&myxf, addrot(xfargs, xdest, ydest, nrm), xfargs);
        copymat4(xm, myxf.xfm);
        if (xfbuf == NULL)
                return(1);
                                /* return xf arguments as well */
        for (i = 0; xfargs[i] != NULL; i++) {
                *xfbuf++ = ' ';
                strcpy(xfbuf, xfargs[i]);
                while (*xfbuf) ++xfbuf;
        }
        return(1);
}

/*######### END DEPRECATED ROUTINES #######*/
/*################################################################*/
Revision:	2.42
Committed:	Sun Sep 2 15:33:15 2012 UTC (11 years, 8 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.41:	+39 -19 lines
Log Message:	Fixes to reciprocity for tensor tree representation