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mkillum4.c

#ifndef lint
static const char RCSid[] = "$Id: mkillum4.c,v 2.9 2008/01/25 02:11:13 greg Exp $";
#endif
/*
 * Routines for handling BSDF data within mkillum
 */

#include "mkillum.h"
#include "paths.h"
#include "ezxml.h"

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

/* BSDF angle specification (terminate with nphi = -1) */
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   3           /* limit on defined bases */

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

      if ((v[2] < -1.0) | (v[2] > 1.0))
            return(-1);
      alt = 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 <= alt; 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      tdia, pdia;
      
      if ((ndx < 0) | (ndx >= ab->nangles))
            return(0);
      for (li = 0; ndx >= ab->lat[li].nphis; li++)
            ndx -= ab->lat[li].nphis;
      if (ab->lat[li].nphis == 1) {       /* special case */
            if (ab->lat[li].tmin > FTINY)
                  error(USER, "unsupported BSDF coordinate system");
            tdia = PI/180. * ab->lat[li+1].tmin;
            return(PI*tdia*tdia);
      }
      tdia = PI/180.*(ab->lat[li+1].tmin - ab->lat[li].tmin);
      tdia *= sin(PI/180.*(ab->lat[li].tmin + ab->lat[li+1].tmin));
      pdia = 2.*PI/ab->lat[li].nphis;
      return(tdia*pdia);
}


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];

      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_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 == NULL) | (rbasis == NULL)) {
            error(WARNING, "missing column/row basis for BSDF");
            return;
      }
      /* XXX need to add routines for loading in foreign bases */
      for (i = nabases; i--; )
            if (!strcmp(cbasis, abase_list[i].name)) {
                  dp->ninc = abase_list[i].nangles;
                  dp->ib_priv = (void *)&abase_list[i];
                  dp->ib_vec = ab_getvec;
                  dp->ib_ndx = ab_getndx;
                  dp->ib_ohm = ab_getohm;
                  break;
            }
      if (i < 0) {
            sprintf(errmsg, "unsupported ColumnAngleBasis '%s'", cbasis);
            error(WARNING, errmsg);
            return;
      }
      for (i = nabases; i--; )
            if (!strcmp(rbasis, abase_list[i].name)) {
                  dp->nout = abase_list[i].nangles;
                  dp->ob_priv = (void *)&abase_list[i];
                  dp->ob_vec = ab_getvecR;
                  dp->ob_ndx = ab_getndxR;
                  dp->ob_ohm = ab_getohm;
                  break;
            }
      if (i < 0) {
            sprintf(errmsg, "unsupported RowAngleBasis '%s'", cbasis);
            error(WARNING, errmsg);
            return;
      }
                        /* read BSDF data */
      sdata  = ezxml_txt(ezxml_child(wdb,"ScatteringData"));
      if (sdata == NULL) {
            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",
                        strlen(sdata));
            error(WARNING, errmsg);
      }
}


struct BSDF_data *
load_BSDF(        /* load BSDF data from file */
      char *fname
)
{
      char              *path;
      ezxml_t                 fl, 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);
      }
      dp = (struct BSDF_data *)calloc(1, sizeof(struct BSDF_data));
      for (wld = ezxml_child(fl, "WavelengthData");
                        wld != NULL; wld = wld->next) {
            if (strcmp(ezxml_txt(ezxml_child(wld,"Wavelength")), "Visible"))
                  continue;
            wdb = ezxml_child(wld, "WavelengthDataBlock");
            if (wdb == NULL) continue;
            if (strcmp(ezxml_txt(ezxml_child(wdb,"WavelengthDataDirection")),
                              "Transmission Front"))
                  continue;
            load_bsdf_data(dp, wdb);      /* load front BTDF */
            break;                        /* ignore the rest */
      }
      ezxml_free(fl);                     /* done with XML file */
      if (dp->bsdf == NULL) {
            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->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);
      multisamp(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);
      multisamp(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);
}


#define  FEQ(a,b) ((a)-(b) <= 1e-7 && (b)-(a) <= 1e-7)

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  *xfargs[7];
      XF    myxf;
      FVECT updir, xdest, ydest;

      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);
      return(1);
}


void
redistribute(           /* pass distarr ray sums through BSDF */
      struct BSDF_data *b,
      int nalt,
      int nazi,
      FVECT u,
      FVECT v,
      FVECT w,
      MAT4 xm
)
{
      int   nout = 0;
      MAT4  mymat, inmat;
      COLORV      *idist;
      COLORV      *cp, *csum;
      FVECT dv;
      double      wt;
      int   i, j, k, o;
      COLOR col, cinc;
                              /* copy incoming distribution */
      if (b->ninc != distsiz)
            error(INTERNAL, "error 1 in redistribute");
      idist = (COLORV *)malloc(sizeof(COLOR)*distsiz);
      if (idist == NULL)
            error(SYSTEM, "out of memory in redistribute");
      memcpy(idist, distarr, sizeof(COLOR)*distsiz);
                              /* compose direction transform */
      for (i = 3; i--; ) {
            mymat[i][0] = u[i];
            mymat[i][1] = v[i];
            mymat[i][2] = w[i];
            mymat[i][3] = 0.;
      }
      mymat[3][0] = mymat[3][1] = mymat[3][2] = 0.;
      mymat[3][3] = 1.;
      if (xm != NULL)
            multmat4(mymat, xm, mymat);
      for (i = 3; i--; ) {          /* make sure it's normalized */
            wt = 1./sqrt(     mymat[0][i]*mymat[0][i] +
                        mymat[1][i]*mymat[1][i] +
                        mymat[2][i]*mymat[2][i] );
            for (j = 3; j--; )
                  mymat[j][i] *= wt;
      }
      if (!invmat4(inmat, mymat))   /* need inverse as well */
            error(INTERNAL, "cannot invert BSDF transform");
      newdist(nalt*nazi);           /* resample distribution */
      for (i = b->ninc; i--; ) {
            getBSDF_incvec(dv, b, i);     /* compute incident irrad. */
            multv3(dv, dv, mymat);
            if (dv[2] < 0.0) dv[2] = -dv[2];
            wt = getBSDF_incohm(b, i);
            wt *= dv[2];                  /* solid_angle*cosine(theta) */
            cp = &idist[3*i];
            copycolor(cinc, cp);
            scalecolor(cinc, wt);
            for (k = nalt; k--; )         /* loop over distribution */
                for (j = nazi; j--; ) {
                  flatdir(dv, (k + .5)/nalt, (double)j/nazi);
                  multv3(dv, dv, inmat);
                                    /* evaluate BSDF @ outgoing */
                  o = getBSDF_outndx(b, dv);
                  if (o < 0) {
                        nout++;
                        continue;
                  }
                  wt = BSDF_value(b, i, o);
                  copycolor(col, cinc);
                  scalecolor(col, wt);
                  csum = &distarr[3*(k*nazi + j)];
                  addcolor(csum, col);    /* sum into distribution */
                }
      }
      free(idist);                  /* free temp space */
      if (nout) {
            sprintf(errmsg, "missing %.1f%% of BSDF directions",
                        100.*nout/(b->ninc*nalt*nazi));
            error(WARNING, errmsg);
      }
}

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