src/common/bsdf_m.c

#ifndef lint
static const char RCSid[] = "$Id: bsdf_m.c,v 3.14 2011/04/25 15:48:05 greg Exp $";
#endif
/*
 *  bsdf_m.c
 *  
 *  Definitions supporting BSDF matrices
 *
 *  Created by Greg Ward on 2/2/11.
 *  Copyright 2011 Anyhere Software. All rights reserved.
 *
 */

#include "rtio.h"
#include <stdlib.h>
#include <math.h>
#include <ctype.h>
#include "ezxml.h"
#include "bsdf.h"
#include "bsdf_m.h"

/* Function return codes */
#define RC_GOOD         1
#define RC_FAIL         0
#define RC_FORMERR      (-1)
#define RC_DATERR       (-2)
#define RC_UNSUPP       (-3)
#define RC_INTERR       (-4)
#define RC_MEMERR       (-5)

#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 */
                int     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 */

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

/* Convert error to standard BSDF code */
static SDError
convert_errcode(int ec)
{
        switch (ec) {
        case RC_GOOD:
                return SDEnone;
        case RC_FORMERR:
                return SDEformat;
        case RC_DATERR:
                return SDEdata;
        case RC_UNSUPP:
                return SDEsupport;
        case RC_INTERR:
                return SDEinternal;
        case RC_MEMERR:
                return SDEmemory;
        }
        return SDEunknown;
}

/* Allocate a BSDF matrix of the given size */
static SDMat *
SDnewMatrix(int ni, int no)
{
        SDMat           *sm;

        if ((ni <= 0) | (no <= 0)) {
                strcpy(SDerrorDetail, "Empty BSDF matrix request");
                return NULL;
        }
        sm = (SDMat *)malloc(sizeof(SDMat) + (ni*no - 1)*sizeof(float));
        if (sm == NULL) {
                sprintf(SDerrorDetail, "Cannot allocate %dx%d BSDF matrix",
                                ni, no);
                return NULL;
        }
        memset(sm, 0, sizeof(SDMat)-sizeof(float));
        sm->ninc = ni;
        sm->nout = no;
        
        return sm;
}

/* Free a BSDF matrix */
#define SDfreeMatrix            free

/* get vector for this angle basis index (front exiting) */
static int
fo_getvec(FVECT v, double ndxr, void *p)
{
        ANGLE_BASIS     *ab = (ANGLE_BASIS *)p;
        int             ndx = (int)ndxr;
        double          randX = ndxr - ndx;
        double          rx[2];
        int             li;
        double          pol, azi, d;
        
        if ((ndxr < 0) | (ndx >= ab->nangles))
                return RC_FAIL;
        for (li = 0; ndx >= ab->lat[li].nphis; li++)
                ndx -= ab->lat[li].nphis;
        SDmultiSamp(rx, 2, randX);
        pol = M_PI/180.*( (1.-rx[0])*ab->lat[li].tmin +
                                rx[0]*ab->lat[li+1].tmin );
        azi = 2.*M_PI*(ndx + rx[1] - .5)/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 RC_GOOD;
}

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

        if (v == NULL)
                return -1;
        if ((v[2] < 0) | (v[2] > 1.))
                return -1;
        pol = 180.0/M_PI*acos(v[2]);
        azi = 180.0/M_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;
}

/* compute square of real value */
static double sq(double x) { return x*x; }

/* get projected solid angle for this angle basis index (universal) */
static double
io_getohm(int ndx, void *p)
{
        static int      last_li = -1;
        static double   last_ohm;
        ANGLE_BASIS     *ab = (ANGLE_BASIS *)p;
        int             li;
        double          theta, theta1;
        
        if ((ndx < 0) | (ndx >= ab->nangles))
                return -1.;
        for (li = 0; ndx >= ab->lat[li].nphis; li++)
                ndx -= ab->lat[li].nphis;
        if (li == last_li)                      /* cached latitude? */
                return last_ohm;
        last_li = li;
        theta1 = M_PI/180. * ab->lat[li+1].tmin;
        if (ab->lat[li].nphis == 1)             /* special case */
                return last_ohm = M_PI*(1. - sq(cos(theta1)));
        theta = M_PI/180. * ab->lat[li].tmin;
        return last_ohm = M_PI*(sq(cos(theta)) - sq(cos(theta1))) /
                                (double)ab->lat[li].nphis;
}

/* get vector for this angle basis index (back incident) */
static int
bi_getvec(FVECT v, double ndxr, void *p)
{
        if (!fo_getvec(v, ndxr, p))
                return RC_FAIL;

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

        return RC_GOOD;
}

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

        return fo_getndx(v2, p);
}

/* get vector for this angle basis index (back exiting) */
static int
bo_getvec(FVECT v, double ndxr, void *p)
{
        if (!fo_getvec(v, ndxr, p))
                return RC_FAIL;

        v[2] = -v[2];

        return RC_GOOD;
}

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

        return fo_getndx(v2, p);
}

/* get vector for this angle basis index (front incident) */
static int
fi_getvec(FVECT v, double ndxr, void *p)
{
        if (!fo_getvec(v, ndxr, p))
                return RC_FAIL;

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

        return RC_GOOD;
}

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

        return fo_getndx(v2, p);
}

/* load custom BSDF angle basis */
static int
load_angle_basis(ezxml_t wab)
{
        char    *abname = ezxml_txt(ezxml_child(wab, "AngleBasisName"));
        ezxml_t wbb;
        int     i;
        
        if (!abname || !*abname)
                return RC_FAIL;
        for (i = nabases; i--; )
                if (!strcasecmp(abname, abase_list[i].name))
                        return RC_GOOD; /* assume it's the same */
        if (nabases >= MAXABASES) {
                sprintf(SDerrorDetail, "Out of angle bases reading '%s'",
                                abname);
                return RC_INTERR;
        }
        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) {
                        sprintf(SDerrorDetail, "Too many latitudes for '%s'",
                                abname);
                        return RC_INTERR;
                }
                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)) {
                        sprintf(SDerrorDetail, "Theta values disagree in '%s'",
                                        abname);
                        return RC_DATERR;
                }
                abase_list[nabases].nangles +=
                        abase_list[nabases].lat[i].nphis =
                                atoi(ezxml_txt(ezxml_child(wbb, "nPhis")));
                if (abase_list[nabases].lat[i].nphis <= 0 ||
                                (abase_list[nabases].lat[i].nphis == 1 &&
                                abase_list[nabases].lat[i].tmin > FTINY)) {
                        sprintf(SDerrorDetail, "Illegal phi count in '%s'",
                                        abname);
                        return RC_DATERR;
                }
        }
        abase_list[nabases++].lat[i].nphis = 0;
        return RC_GOOD;
}

/* compute min. proj. solid angle and max. direct hemispherical scattering */
static int
get_extrema(SDSpectralDF *df)
{
        SDMat   *dp = (SDMat *)df->comp[0].dist;
        double  *ohma;
        int     i, o;
                                        /* initialize extrema */
        df->minProjSA = M_PI;
        df->maxHemi = .0;
        ohma = (double *)malloc(dp->nout*sizeof(double));
        if (ohma == NULL)
                return RC_MEMERR;
                                        /* get outgoing solid angles */
        for (o = dp->nout; o--; )
                if ((ohma[o] = mBSDF_outohm(dp,o)) < df->minProjSA)
                        df->minProjSA = ohma[o];
                                        /* compute hemispherical sums */
        for (i = dp->ninc; i--; ) {
                double  hemi = .0;
                for (o = dp->nout; o--; )
                        hemi += ohma[o] * mBSDF_value(dp, i, o);
                if (hemi > df->maxHemi)
                        df->maxHemi = hemi;
        }
        free(ohma);
                                        /* need incoming solid angles, too? */
        if ((dp->ib_ohm != dp->ob_ohm) | (dp->ib_priv != dp->ob_priv)) {
                double  ohm;
                for (i = dp->ninc; i--; )
                        if ((ohm = mBSDF_incohm(dp,i)) < df->minProjSA)
                                df->minProjSA = ohm;
        }
        return (df->maxHemi <= 1.01);
}

/* load BSDF distribution for this wavelength */
static int
load_bsdf_data(SDData *sd, ezxml_t wdb, int rowinc)
{
        SDSpectralDF    *df;
        SDMat           *dp;
        char            *sdata;
        int             tfront;
        int             inbi, outbi;
        int             i;
                                        /* allocate BSDF component */
        sdata = ezxml_txt(ezxml_child(wdb, "WavelengthDataDirection"));
        if (!sdata)
                return RC_FAIL;
        /*
         * Remember that front and back are reversed from WINDOW 6 orientations
         * Favor their "Front" (incoming light) since that's more often valid
         */
        tfront = !strcasecmp(sdata, "Transmission Back");
        if (!strcasecmp(sdata, "Transmission Front") ||
                        tfront & (sd->tf == NULL)) {
                if (sd->tf != NULL)
                        SDfreeSpectralDF(sd->tf);
                if ((sd->tf = SDnewSpectralDF(1)) == NULL)
                        return RC_MEMERR;
                df = sd->tf;
        } else if (!strcasecmp(sdata, "Reflection Front")) {
                if (sd->rb != NULL)     /* note back-front reversal */
                        SDfreeSpectralDF(sd->rb);
                if ((sd->rb = SDnewSpectralDF(1)) == NULL)
                        return RC_MEMERR;
                df = sd->rb;
        } else if (!strcasecmp(sdata, "Reflection Back")) {
                if (sd->rf != NULL)     /* note front-back reversal */
                        SDfreeSpectralDF(sd->rf);
                if ((sd->rf = SDnewSpectralDF(1)) == NULL)
                        return RC_MEMERR;
                df = sd->rf;
        } else
                return RC_FAIL;
        /* XXX should also check "ScatteringDataType" for consistency? */
                                        /* get angle bases */
        sdata = ezxml_txt(ezxml_child(wdb,"ColumnAngleBasis"));
        if (!sdata || !*sdata) {
                sprintf(SDerrorDetail, "Missing column basis for BSDF '%s'",
                                sd->name);
                return RC_FORMERR;
        }
        for (inbi = nabases; inbi--; )
                if (!strcasecmp(sdata, abase_list[inbi].name))
                        break;
        if (inbi < 0) {
                sprintf(SDerrorDetail, "Undefined ColumnAngleBasis '%s'", sdata);
                return RC_FORMERR;
        }
        sdata = ezxml_txt(ezxml_child(wdb,"RowAngleBasis"));
        if (!sdata || !*sdata) {
                sprintf(SDerrorDetail, "Missing row basis for BSDF '%s'",
                                sd->name);
                return RC_FORMERR;
        }
        for (outbi = nabases; outbi--; )
                if (!strcasecmp(sdata, abase_list[outbi].name))
                        break;
        if (outbi < 0) {
                sprintf(SDerrorDetail, "Undefined RowAngleBasis '%s'", sdata);
                return RC_FORMERR;
        }
                                        /* allocate BSDF matrix */
        dp = SDnewMatrix(abase_list[inbi].nangles, abase_list[outbi].nangles);
        if (dp == NULL)
                return RC_MEMERR;
        dp->ib_priv = &abase_list[inbi];
        dp->ob_priv = &abase_list[outbi];
        if (df == sd->tf) {
                if (tfront) {
                        dp->ib_vec = &fi_getvec;
                        dp->ib_ndx = &fi_getndx;
                        dp->ob_vec = &bo_getvec;
                        dp->ob_ndx = &bo_getndx;
                } else {
                        dp->ib_vec = &bi_getvec;
                        dp->ib_ndx = &bi_getndx;
                        dp->ob_vec = &fo_getvec;
                        dp->ob_ndx = &fo_getndx;
                }
        } else if (df == sd->rf) {
                dp->ib_vec = &fi_getvec;
                dp->ib_ndx = &fi_getndx;
                dp->ob_vec = &fo_getvec;
                dp->ob_ndx = &fo_getndx;
        } else /* df == sd->rb */ {
                dp->ib_vec = &bi_getvec;
                dp->ib_ndx = &bi_getndx;
                dp->ob_vec = &bo_getvec;
                dp->ob_ndx = &bo_getndx;
        }
        dp->ib_ohm = &io_getohm;
        dp->ob_ohm = &io_getohm;
        df->comp[0].cspec[0] = c_dfcolor; /* XXX monochrome for now */
        df->comp[0].dist = dp;
        df->comp[0].func = &SDhandleMtx;
                                        /* read BSDF data */
        sdata = ezxml_txt(ezxml_child(wdb, "ScatteringData"));
        if (!sdata || !*sdata) {
                sprintf(SDerrorDetail, "Missing BSDF ScatteringData in '%s'",
                                sd->name);
                return RC_FORMERR;
        }
        for (i = 0; i < dp->ninc*dp->nout; i++) {
                char  *sdnext = fskip(sdata);
                if (sdnext == NULL) {
                        sprintf(SDerrorDetail,
                                "Bad/missing BSDF ScatteringData in '%s'",
                                        sd->name);
                        return RC_FORMERR;
                }
                while (isspace(*sdnext))
                        sdnext++;
                if (*sdnext == ',') sdnext++;
                if (rowinc) {
                        int     r = i/dp->nout;
                        int     c = i - c*dp->nout;
                        mBSDF_value(dp,r,c) = atof(sdata);
                } else
                        dp->bsdf[i] = atof(sdata);
                sdata = sdnext;
        }
        return get_extrema(df);
}

/* Subtract minimum (diffuse) scattering amount from BSDF */
static double
subtract_min(SDMat *sm)
{
        float   minv = sm->bsdf[0];
        int     n = sm->ninc*sm->nout;
        int     i;
        
        for (i = n; --i; )
                if (sm->bsdf[i] < minv)
                        minv = sm->bsdf[i];
        
        if (minv <= FTINY)
                return .0;

        for (i = n; i--; )
                sm->bsdf[i] -= minv;

        return minv*M_PI;               /* be sure to include multiplier */
}

/* Extract and separate diffuse portion of BSDF */
static void
extract_diffuse(SDValue *dv, SDSpectralDF *df)
{
        int     n;

        if (df == NULL || df->ncomp <= 0) {
                dv->spec = c_dfcolor;
                dv->cieY = .0;
                return;
        }
        dv->spec = df->comp[0].cspec[0];
        dv->cieY = subtract_min((SDMat *)df->comp[0].dist);
                                        /* in case of multiple components */
        for (n = df->ncomp; --n; ) {
                double  ymin = subtract_min((SDMat *)df->comp[n].dist);
                c_cmix(&dv->spec, dv->cieY, &dv->spec, ymin, &df->comp[n].cspec[0]);
                dv->cieY += ymin;
        }
        df->maxHemi -= dv->cieY;        /* adjust maximum hemispherical */
                                        /* make sure everything is set */
        c_ccvt(&dv->spec, C_CSXY+C_CSSPEC);
}

/* Load a BSDF matrix from an open XML file */
SDError
SDloadMtx(SDData *sd, ezxml_t wtl)
{
        ezxml_t         wld, wdb;
        int             rowIn;
        char            *txt;
        int             rval;
                                        /* basic checks and data ordering */
        txt = ezxml_txt(ezxml_child(ezxml_child(wtl,
                        "DataDefinition"), "IncidentDataStructure"));
        if (txt == NULL || !*txt) {
                sprintf(SDerrorDetail,
                        "BSDF \"%s\": missing IncidentDataStructure",
                                sd->name);
                return SDEformat;
        }
        if (!strcasecmp(txt, "Rows"))
                rowIn = 1;
        else if (!strcasecmp(txt, "Columns"))
                rowIn = 0;
        else {
                sprintf(SDerrorDetail,
                        "BSDF \"%s\": unsupported IncidentDataStructure",
                                sd->name);
                return SDEsupport;
        }
                                        /* get angle basis */
        rval = load_angle_basis(ezxml_child(ezxml_child(wtl,
                                "DataDefinition"), "AngleBasis"));
        if (rval < 0)
                return convert_errcode(rval);
                                        /* load BSDF components */
        for (wld = ezxml_child(wtl, "WavelengthData");
                                wld != NULL; wld = wld->next) {
                if (strcasecmp(ezxml_txt(ezxml_child(wld,"Wavelength")),
                                "Visible"))
                        continue;       /* just visible for now */
                for (wdb = ezxml_child(wld, "WavelengthDataBlock");
                                        wdb != NULL; wdb = wdb->next)
                        if ((rval = load_bsdf_data(sd, wdb, rowIn)) < 0)
                                return convert_errcode(rval);
        }
                                        /* separate diffuse components */
        extract_diffuse(&sd->rLambFront, sd->rf);
        extract_diffuse(&sd->rLambBack, sd->rb);
        extract_diffuse(&sd->tLamb, sd->tf);
                                        /* return success */
        return SDEnone;
}

/* Get Matrix BSDF value */
static int
SDgetMtxBSDF(float coef[SDmaxCh], const FVECT outVec,
                                const FVECT inVec, SDComponent *sdc)
{
        const SDMat     *dp;
        int             i_ndx, o_ndx;
                                        /* check arguments */
        if ((coef == NULL) | (outVec == NULL) | (inVec == NULL) | (sdc == NULL)
                        || (dp = (SDMat *)sdc->dist) == NULL)
                return 0;
                                        /* get angle indices */
        i_ndx = mBSDF_incndx(dp, inVec);
        o_ndx = mBSDF_outndx(dp, outVec);
                                        /* try reciprocity if necessary */
        if ((i_ndx < 0) & (o_ndx < 0)) {
                i_ndx = mBSDF_incndx(dp, outVec);
                o_ndx = mBSDF_outndx(dp, inVec);
        }
        if ((i_ndx < 0) | (o_ndx < 0))
                return 0;               /* nothing from this component */
        coef[0] = mBSDF_value(dp, i_ndx, o_ndx);
        return 1;                       /* XXX monochrome for now */
}

/* Query solid angle for vector(s) */
static SDError
SDqueryMtxProjSA(double *psa, const FVECT v1, const RREAL *v2,
                                        int qflags, SDComponent *sdc)
{
        const SDMat     *dp;
        double          inc_psa, out_psa;
                                        /* check arguments */
        if ((psa == NULL) | (v1 == NULL) | (sdc == NULL) ||
                        (dp = (SDMat *)sdc->dist) == NULL)
                return SDEargument;
        if (v2 == NULL)
                v2 = v1;
                                        /* get projected solid angles */
        out_psa = mBSDF_outohm(dp, mBSDF_outndx(dp, v1));
        inc_psa = mBSDF_incohm(dp, mBSDF_incndx(dp, v2));
        if ((v1 != v2) & (out_psa <= 0) & (inc_psa <= 0)) {
                inc_psa = mBSDF_outohm(dp, mBSDF_outndx(dp, v2));
                out_psa = mBSDF_incohm(dp, mBSDF_incndx(dp, v1));
        }

        switch (qflags) {               /* record based on flag settings */
        case SDqueryMax:
                if (inc_psa > psa[0])
                        psa[0] = inc_psa;
                if (out_psa > psa[0])
                        psa[0] = out_psa;
                break;
        case SDqueryMin+SDqueryMax:
                if (inc_psa > psa[1])
                        psa[1] = inc_psa;
                if (out_psa > psa[1])
                        psa[1] = out_psa;
                /* fall through */
        case SDqueryVal:
                if (qflags == SDqueryVal)
                        psa[0] = M_PI;
                /* fall through */
        case SDqueryMin:
                if ((inc_psa > 0) & (inc_psa < psa[0]))
                        psa[0] = inc_psa;
                if ((out_psa > 0) & (out_psa < psa[0]))
                        psa[0] = out_psa;
                break;
        }
                                        /* make sure it's legal */
        return (psa[0] <= 0) ? SDEinternal : SDEnone;
}

/* Compute new cumulative distribution from BSDF */
static int
make_cdist(SDMatCDst *cd, const FVECT inVec, SDMat *dp, int rev)
{
        const unsigned  maxval = ~0;
        double          *cmtab, scale;
        int             o;

        cmtab = (double *)malloc((cd->calen+1)*sizeof(double));
        if (cmtab == NULL)
                return 0;
        cmtab[0] = .0;
        for (o = 0; o < cd->calen; o++) {
                if (rev)
                        cmtab[o+1] = mBSDF_value(dp, o, cd->indx) *
                                        (*dp->ib_ohm)(o, dp->ib_priv);
                else
                        cmtab[o+1] = mBSDF_value(dp, cd->indx, o) *
                                        (*dp->ob_ohm)(o, dp->ob_priv);
                cmtab[o+1] += cmtab[o];
        }
        cd->cTotal = cmtab[cd->calen];
        scale = (double)maxval / cd->cTotal;
        cd->carr[0] = 0;
        for (o = 1; o < cd->calen; o++)
                cd->carr[o] = scale*cmtab[o] + .5;
        cd->carr[cd->calen] = maxval;
        free(cmtab);
        return 1;
}

/* Get cumulative distribution for matrix BSDF */
static const SDCDst *
SDgetMtxCDist(const FVECT inVec, SDComponent *sdc)
{
        SDMat           *dp;
        int             reverse;
        SDMatCDst       myCD;
        SDMatCDst       *cd, *cdlast;
                                        /* check arguments */
        if ((inVec == NULL) | (sdc == NULL) ||
                        (dp = (SDMat *)sdc->dist) == NULL)
                return NULL;
        memset(&myCD, 0, sizeof(myCD));
        myCD.indx = mBSDF_incndx(dp, inVec);
        if (myCD.indx >= 0) {
                myCD.ob_priv = dp->ob_priv;
                myCD.ob_vec = dp->ob_vec;
                myCD.calen = dp->nout;
                reverse = 0;
        } else {                        /* try reciprocity */
                myCD.indx = mBSDF_outndx(dp, inVec);
                if (myCD.indx < 0)
                        return NULL;
                myCD.ob_priv = dp->ib_priv;
                myCD.ob_vec = dp->ib_vec;
                myCD.calen = dp->ninc;
                reverse = 1;
        }
        cdlast = NULL;                  /* check for it in cache list */
        for (cd = (SDMatCDst *)sdc->cdList; cd != NULL;
                                cdlast = cd, cd = (SDMatCDst *)cd->next)
                if (cd->indx == myCD.indx && (cd->calen == myCD.calen) &
                                        (cd->ob_priv == myCD.ob_priv) &
                                        (cd->ob_vec == myCD.ob_vec))
                        break;
        if (cd == NULL) {               /* need to allocate new entry */
                cd = (SDMatCDst *)malloc(sizeof(SDMatCDst) +
                                        sizeof(myCD.carr[0])*myCD.calen);
                if (cd == NULL)
                        return NULL;
                *cd = myCD;             /* compute cumulative distribution */
                if (!make_cdist(cd, inVec, dp, reverse)) {
                        free(cd);
                        return NULL;
                }
                cdlast = cd;
        }
        if (cdlast != NULL) {           /* move entry to head of cache list */
                cdlast->next = cd->next;
                cd->next = sdc->cdList;
                sdc->cdList = (SDCDst *)cd;
        }
        return (SDCDst *)cd;            /* ready to go */
}

/* Sample cumulative distribution */
static SDError
SDsampMtxCDist(FVECT ioVec, double randX, const SDCDst *cdp)
{
        const unsigned  maxval = ~0;
        const SDMatCDst *mcd = (const SDMatCDst *)cdp;
        const unsigned  target = randX*maxval;
        int             i, iupper, ilower;
                                        /* check arguments */
        if ((ioVec == NULL) | (mcd == NULL))
                return SDEargument;
                                        /* binary search to find index */
        ilower = 0; iupper = mcd->calen;
        while ((i = (iupper + ilower) >> 1) != ilower)
                if ((long)target >= (long)mcd->carr[i])
                        ilower = i;
                else
                        iupper = i;
                                        /* localize random position */
        randX = (randX*maxval - mcd->carr[ilower]) /
                        (double)(mcd->carr[iupper] - mcd->carr[ilower]);
                                        /* convert index to vector */
        if ((*mcd->ob_vec)(ioVec, i+randX, mcd->ob_priv))
                return SDEnone;
        strcpy(SDerrorDetail, "Matrix BSDF sampling fault");
        return SDEinternal;
}

/* Fixed resolution BSDF methods */
SDFunc                  SDhandleMtx = {
                                &SDgetMtxBSDF,
                                &SDqueryMtxProjSA,
                                &SDgetMtxCDist,
                                &SDsampMtxCDist,
                                &SDfreeMatrix,
                        };
Revision:	3.15
Committed:	Wed Apr 27 20:03:25 2011 UTC (13 years ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 3.14:	+19 -14 lines
Log Message:	Initial untested variable-resolution BSDF