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Fri, Nov 8, 03:22

m_bsdf.c
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#ifndef lint
static const char RCSid[] = "$Id: m_bsdf.c,v 2.70 2022/03/09 00:27:25 greg Exp $";
#endif
/*
* Shading for materials with BSDFs taken from XML data files
*/
#include "copyright.h"
#include "ray.h"
#include "otypes.h"
#include "ambient.h"
#include "source.h"
#include "func.h"
#include "bsdf.h"
#include "random.h"
#include "pmapmat.h"
/*
* Arguments to this material include optional diffuse colors.
* String arguments include the BSDF and function files.
* For the MAT_BSDF type, a non-zero thickness causes the useful behavior
* of translating transmitted rays this distance beneath the surface
* (opposite the surface normal) to bypass any intervening geometry.
* Translation only affects scattered, non-source-directed samples.
* A non-zero thickness has the further side-effect that an unscattered
* (view) ray will pass right through our material, making the BSDF
* surface invisible and showing the proxied geometry instead. Thickness
* has the further effect of turning off reflection on the reverse side so
* rays heading in the opposite direction pass unimpeded through the BSDF
* surface. A paired surface may be placed on the opposide side of
* the detail geometry, less than this thickness away, if a two-way
* proxy is desired. Note that the sign of the thickness is important.
* A positive thickness hides geometry behind the BSDF surface and uses
* front reflectance and transmission properties. A negative thickness
* hides geometry in front of the surface when rays hit from behind,
* and applies only the transmission and backside reflectance properties.
* Reflection is ignored on the hidden side, as those rays pass through.
* For the MAT_ABSDF type, we check for a strong "through" component.
* Such a component will cause direct rays to pass through unscattered.
* A separate test prevents over-counting by dropping samples that are
* too close to this "through" direction. BSDFs with such a through direction
* will also have a view component, meaning they are somewhat see-through.
* A MAT_BSDF type with zero thickness behaves the same as a MAT_ABSDF
* type with no strong through component.
* The "up" vector for the BSDF is given by three variables, defined
* (along with the thickness) by the named function file, or '.' if none.
* Together with the surface normal, this defines the local coordinate
* system for the BSDF.
* We do not reorient the surface, so if the BSDF has no back-side
* reflectance and none is given in the real arguments, a BSDF surface
* with zero thickness will appear black when viewed from behind
* unless backface visibility is on, when it becomes invisible.
* The diffuse arguments are added to components in the BSDF file,
* not multiplied. However, patterns affect this material as a multiplier
* on everything except non-diffuse reflection.
*
* Arguments for MAT_ABSDF are:
* 5+ BSDFfile ux uy uz funcfile transform
* 0
* 0|3|6|9 rdf gdf bdf
* rdb gdb bdb
* rdt gdt bdt
*
* Arguments for MAT_BSDF are:
* 6+ thick BSDFfile ux uy uz funcfile transform
* 0
* 0|3|6|9 rdf gdf bdf
* rdb gdb bdb
* rdt gdt bdt
*/
/*
* Note that our reverse ray-tracing process means that the positions
* of incoming and outgoing vectors may be reversed in our calls
* to the BSDF library. This is usually fine, since the bidirectional nature
* of the BSDF (that's what the 'B' stands for) means it all works out.
*/
typedef struct {
OBJREC *mp; /* material pointer */
RAY *pr; /* intersected ray */
FVECT pnorm; /* perturbed surface normal */
FVECT vray; /* local outgoing (return) vector */
double sr_vpsa[2]; /* sqrt of BSDF projected solid angle extrema */
RREAL toloc[3][3]; /* world to local BSDF coords */
RREAL fromloc[3][3]; /* local BSDF coords to world */
double thick; /* surface thickness */
COLOR cthru; /* "through" component for MAT_ABSDF */
COLOR cthru_surr; /* surround for "through" component */
SDData *sd; /* loaded BSDF data */
COLOR rdiff; /* diffuse reflection */
COLOR runsamp; /* BSDF hemispherical reflection */
COLOR tdiff; /* diffuse transmission */
COLOR tunsamp; /* BSDF hemispherical transmission */
} BSDFDAT; /* BSDF material data */
#define cvt_sdcolor(cv, svp) ccy2rgb(&(svp)->spec, (svp)->cieY, cv)
typedef struct {
double vy; /* brightness (for sorting) */
FVECT tdir; /* through sample direction (normalized) */
COLOR vcol; /* BTDF color */
} PEAKSAMP; /* BTDF peak sample */
/* Comparison function to put near-peak values in descending order */
static int
cmp_psamp(const void *p1, const void *p2)
{
double diff = (*(const PEAKSAMP *)p1).vy - (*(const PEAKSAMP *)p2).vy;
if (diff > 0) return(-1);
if (diff < 0) return(1);
return(0);
}
/* Compute "through" component color for MAT_ABSDF */
static void
compute_through(BSDFDAT *ndp)
{
#define NDIR2CHECK 29
static const float dir2check[NDIR2CHECK][2] = {
{0, 0}, {-0.6, 0}, {0, 0.6},
{0, -0.6}, {0.6, 0}, {-0.6, 0.6},
{-0.6, -0.6}, {0.6, 0.6}, {0.6, -0.6},
{-1.2, 0}, {0, 1.2}, {0, -1.2},
{1.2, 0}, {-1.2, 1.2}, {-1.2, -1.2},
{1.2, 1.2}, {1.2, -1.2}, {-1.8, 0},
{0, 1.8}, {0, -1.8}, {1.8, 0},
{-1.8, 1.8}, {-1.8, -1.8}, {1.8, 1.8},
{1.8, -1.8}, {-2.4, 0}, {0, 2.4},
{0, -2.4}, {2.4, 0},
};
PEAKSAMP psamp[NDIR2CHECK];
SDSpectralDF *dfp;
FVECT pdir;
double tomega, srchrad;
double tomsum, tomsurr;
COLOR vpeak, vsurr, btdiff;
double vypeak;
int i, ns;
SDError ec;
if (ndp->pr->rod > 0)
dfp = (ndp->sd->tf != NULL) ? ndp->sd->tf : ndp->sd->tb;
else
dfp = (ndp->sd->tb != NULL) ? ndp->sd->tb : ndp->sd->tf;
if (dfp == NULL)
return; /* no specular transmission */
if (bright(ndp->pr->pcol) <= FTINY)
return; /* pattern is black, here */
srchrad = sqrt(dfp->minProjSA); /* else evaluate peak */
for (i = 0; i < NDIR2CHECK; i++) {
SDValue sv;
psamp[i].tdir[0] = -ndp->vray[0] + dir2check[i][0]*srchrad;
psamp[i].tdir[1] = -ndp->vray[1] + dir2check[i][1]*srchrad;
psamp[i].tdir[2] = -ndp->vray[2];
normalize(psamp[i].tdir);
ec = SDevalBSDF(&sv, ndp->vray, psamp[i].tdir, ndp->sd);
if (ec)
goto baderror;
cvt_sdcolor(psamp[i].vcol, &sv);
psamp[i].vy = sv.cieY;
}
qsort(psamp, NDIR2CHECK, sizeof(PEAKSAMP), cmp_psamp);
if (psamp[0].vy <= FTINY)
return; /* zero BTDF here */
setcolor(vpeak, 0, 0, 0);
setcolor(vsurr, 0, 0, 0);
vypeak = tomsum = tomsurr = 0; /* combine top unique values */
ns = 0;
for (i = 0; i < NDIR2CHECK; i++) {
if (i && psamp[i].vy == psamp[i-1].vy)
continue; /* assume duplicate sample */
ec = SDsizeBSDF(&tomega, ndp->vray, psamp[i].tdir,
SDqueryMin, ndp->sd);
if (ec)
goto baderror;
scalecolor(psamp[i].vcol, tomega);
/* not part of peak? */
if (tomega > 1.5*dfp->minProjSA ||
vypeak > 8.*psamp[i].vy*ns) {
if (!i) return; /* abort */
addcolor(vsurr, psamp[i].vcol);
tomsurr += tomega;
continue;
}
addcolor(vpeak, psamp[i].vcol);
tomsum += tomega;
vypeak += psamp[i].vy;
++ns;
}
if (tomsurr < 0.2*tomsum) /* insufficient surround? */
return;
scalecolor(vsurr, 1./tomsurr); /* surround is avg. BTDF */
if (ndp->vray[2] > 0) /* get diffuse BTDF */
cvt_sdcolor(btdiff, &ndp->sd->tLambFront);
else
cvt_sdcolor(btdiff, &ndp->sd->tLambBack);
scalecolor(btdiff, (1./PI));
for (i = 3; i--; ) { /* remove diffuse contrib. */
if ((colval(vpeak,i) -= tomsum*colval(btdiff,i)) < 0)
colval(vpeak,i) = 0;
if ((colval(vsurr,i) -= colval(btdiff,i)) < 0)
colval(vsurr,i) = 0;
}
if (bright(vpeak) < .0005) /* < 0.05% specular? */
return;
multcolor(vsurr, ndp->pr->pcol); /* modify by color */
multcolor(vpeak, ndp->pr->pcol);
copycolor(ndp->cthru, vpeak);
copycolor(ndp->cthru_surr, vsurr);
return;
baderror:
objerror(ndp->mp, USER, transSDError(ec));
#undef NDIR2CHECK
}
/* Jitter ray sample according to projected solid angle and specjitter */
static void
bsdf_jitter(FVECT vres, BSDFDAT *ndp, double sr_psa)
{
VCOPY(vres, ndp->vray);
if (specjitter < 1.)
sr_psa *= specjitter;
if (sr_psa <= FTINY)
return;
vres[0] += sr_psa*(.5 - frandom());
vres[1] += sr_psa*(.5 - frandom());
normalize(vres);
}
/* Get BSDF specular for direct component, returning true if OK to proceed */
static int
direct_specular_OK(COLOR cval, FVECT ldir, double omega, BSDFDAT *ndp)
{
int nsamp = 1;
int scnt = 0;
FVECT vsrc, vjit;
double tomega, tomega2;
double sf, tsr, sd[2];
COLOR csmp, cdiff;
double diffY;
SDValue sv;
SDError ec;
int i;
/* in case we fail */
setcolor(cval, 0, 0, 0);
/* transform source direction */
if (SDmapDir(vsrc, ndp->toloc, ldir) != SDEnone)
return(0);
/* check indirect over-counting */
if ((vsrc[2] > 0) ^ (ndp->vray[2] > 0) && bright(ndp->cthru) > FTINY) {
double dx = vsrc[0] + ndp->vray[0];
double dy = vsrc[1] + ndp->vray[1];
SDSpectralDF *dfp = (ndp->pr->rod > 0) ?
((ndp->sd->tf != NULL) ? ndp->sd->tf : ndp->sd->tb) :
((ndp->sd->tb != NULL) ? ndp->sd->tb : ndp->sd->tf) ;
tomega = omega*fabs(vsrc[2]);
if (dx*dx + dy*dy <= (2.5*4./PI)*(tomega + dfp->minProjSA +
2.*sqrt(tomega*dfp->minProjSA))) {
if (bright(ndp->cthru_surr) <= FTINY)
return(0);
copycolor(cval, ndp->cthru_surr);
return(1); /* return non-zero surround BTDF */
}
}
/* will discount diffuse portion */
switch ((vsrc[2] > 0)<<1 | (ndp->vray[2] > 0)) {
case 3:
if (ndp->sd->rf == NULL)
return(0); /* all diffuse */
sv = ndp->sd->rLambFront;
break;
case 0:
if (ndp->sd->rb == NULL)
return(0); /* all diffuse */
sv = ndp->sd->rLambBack;
break;
case 1:
if ((ndp->sd->tf == NULL) & (ndp->sd->tb == NULL))
return(0); /* all diffuse */
sv = ndp->sd->tLambFront;
break;
case 2:
if ((ndp->sd->tf == NULL) & (ndp->sd->tb == NULL))
return(0); /* all diffuse */
sv = ndp->sd->tLambBack;
break;
}
if (sv.cieY > FTINY) {
diffY = sv.cieY *= 1./PI;
cvt_sdcolor(cdiff, &sv);
} else {
diffY = 0;
setcolor(cdiff, 0, 0, 0);
}
ec = SDsizeBSDF(&tomega, ndp->vray, vsrc, SDqueryMin, ndp->sd);
if (ec)
goto baderror;
/* check if sampling BSDF */
if ((tsr = sqrt(tomega)) > 0) {
nsamp = 4.*specjitter*ndp->pr->rweight + .5;
nsamp += !nsamp;
}
/* jitter to fuzz BSDF cells */
for (i = nsamp; i--; ) {
bsdf_jitter(vjit, ndp, tsr);
/* compute BSDF */
ec = SDevalBSDF(&sv, vjit, vsrc, ndp->sd);
if (ec)
goto baderror;
if (sv.cieY - diffY <= FTINY)
continue; /* no specular part */
/* check for variable resolution */
ec = SDsizeBSDF(&tomega2, vjit, vsrc, SDqueryMin, ndp->sd);
if (ec)
goto baderror;
if (tomega2 < .12*tomega)
continue; /* not safe to include */
cvt_sdcolor(csmp, &sv);
addcolor(cval, csmp);
++scnt;
}
if (!scnt) /* no valid specular samples? */
return(0);
sf = 1./scnt; /* weighted average BSDF */
scalecolor(cval, sf);
/* subtract diffuse contribution */
for (i = 3*(diffY > FTINY); i--; )
if ((colval(cval,i) -= colval(cdiff,i)) < 0)
colval(cval,i) = 0;
return(1);
baderror:
objerror(ndp->mp, USER, transSDError(ec));
return(0); /* gratis return */
}
/* Compute source contribution for BSDF (reflected & transmitted) */
static void
dir_bsdf(
COLOR cval, /* returned coefficient */
void *nnp, /* material data */
FVECT ldir, /* light source direction */
double omega /* light source size */
)
{
BSDFDAT *np = (BSDFDAT *)nnp;
double ldot;
double dtmp;
COLOR ctmp;
setcolor(cval, 0, 0, 0);
ldot = DOT(np->pnorm, ldir);
if ((-FTINY <= ldot) & (ldot <= FTINY))
return;
if (ldot > 0 && bright(np->rdiff) > FTINY) {
/*
* Compute diffuse reflected component
*/
copycolor(ctmp, np->rdiff);
dtmp = ldot * omega * (1./PI);
scalecolor(ctmp, dtmp);
addcolor(cval, ctmp);
}
if (ldot < 0 && bright(np->tdiff) > FTINY) {
/*
* Compute diffuse transmission
*/
copycolor(ctmp, np->tdiff);
dtmp = -ldot * omega * (1./PI);
scalecolor(ctmp, dtmp);
addcolor(cval, ctmp);
}
if (ambRayInPmap(np->pr))
return; /* specular already in photon map */
/*
* Compute specular scattering coefficient using BSDF
*/
if (!direct_specular_OK(ctmp, ldir, omega, np))
return;
if (ldot < 0) { /* pattern for specular transmission */
multcolor(ctmp, np->pr->pcol);
dtmp = -ldot * omega;
} else
dtmp = ldot * omega;
scalecolor(ctmp, dtmp);
addcolor(cval, ctmp);
}
/* Compute source contribution for BSDF (reflected only) */
static void
dir_brdf(
COLOR cval, /* returned coefficient */
void *nnp, /* material data */
FVECT ldir, /* light source direction */
double omega /* light source size */
)
{
BSDFDAT *np = (BSDFDAT *)nnp;
double ldot;
double dtmp;
COLOR ctmp, ctmp1, ctmp2;
setcolor(cval, 0, 0, 0);
ldot = DOT(np->pnorm, ldir);
if (ldot <= FTINY)
return;
if (bright(np->rdiff) > FTINY) {
/*
* Compute diffuse reflected component
*/
copycolor(ctmp, np->rdiff);
dtmp = ldot * omega * (1./PI);
scalecolor(ctmp, dtmp);
addcolor(cval, ctmp);
}
if (ambRayInPmap(np->pr))
return; /* specular already in photon map */
/*
* Compute specular reflection coefficient using BSDF
*/
if (!direct_specular_OK(ctmp, ldir, omega, np))
return;
dtmp = ldot * omega;
scalecolor(ctmp, dtmp);
addcolor(cval, ctmp);
}
/* Compute source contribution for BSDF (transmitted only) */
static void
dir_btdf(
COLOR cval, /* returned coefficient */
void *nnp, /* material data */
FVECT ldir, /* light source direction */
double omega /* light source size */
)
{
BSDFDAT *np = (BSDFDAT *)nnp;
double ldot;
double dtmp;
COLOR ctmp;
setcolor(cval, 0, 0, 0);
ldot = DOT(np->pnorm, ldir);
if (ldot >= -FTINY)
return;
if (bright(np->tdiff) > FTINY) {
/*
* Compute diffuse transmission
*/
copycolor(ctmp, np->tdiff);
dtmp = -ldot * omega * (1./PI);
scalecolor(ctmp, dtmp);
addcolor(cval, ctmp);
}
if (ambRayInPmap(np->pr))
return; /* specular already in photon map */
/*
* Compute specular scattering coefficient using BSDF
*/
if (!direct_specular_OK(ctmp, ldir, omega, np))
return;
/* full pattern on transmission */
multcolor(ctmp, np->pr->pcol);
dtmp = -ldot * omega;
scalecolor(ctmp, dtmp);
addcolor(cval, ctmp);
}
/* Sample separate BSDF component */
static int
sample_sdcomp(BSDFDAT *ndp, SDComponent *dcp, int xmit)
{
const int hasthru = (xmit &&
!(ndp->pr->crtype & (SPECULAR|AMBIENT))
&& bright(ndp->cthru) > FTINY);
int nstarget = 1;
int nsent = 0;
int n;
SDError ec;
SDValue bsv;
double xrand;
FVECT vsmp, vinc;
RAY sr;
/* multiple samples? */
if (specjitter > 1.5) {
nstarget = specjitter*ndp->pr->rweight + .5;
nstarget += !nstarget;
}
/* run through our samples */
for (n = 0; n < nstarget; n++) {
if (nstarget == 1) { /* stratify random variable */
xrand = urand(ilhash(dimlist,ndims)+samplendx);
if (specjitter < 1.)
xrand = .5 + specjitter*(xrand-.5);
} else {
xrand = (n + frandom())/(double)nstarget;
}
SDerrorDetail[0] = '\0'; /* sample direction & coef. */
bsdf_jitter(vsmp, ndp, ndp->sr_vpsa[0]);
VCOPY(vinc, vsmp); /* to compare after */
ec = SDsampComponent(&bsv, vsmp, xrand, dcp);
if (ec)
objerror(ndp->mp, USER, transSDError(ec));
if (bsv.cieY <= FTINY) /* zero component? */
break;
if (hasthru) { /* check for view ray */
double dx = vinc[0] + vsmp[0];
double dy = vinc[1] + vsmp[1];
if (dx*dx + dy*dy <= ndp->sr_vpsa[0]*ndp->sr_vpsa[0])
continue; /* exclude view sample */
}
/* map non-view sample->world */
if (SDmapDir(sr.rdir, ndp->fromloc, vsmp) != SDEnone)
break;
/* spawn a specular ray */
if (nstarget > 1)
bsv.cieY /= (double)nstarget;
cvt_sdcolor(sr.rcoef, &bsv); /* use sample color */
if (xmit) /* apply pattern on transmit */
multcolor(sr.rcoef, ndp->pr->pcol);
if (rayorigin(&sr, SPECULAR, ndp->pr, sr.rcoef) < 0) {
if (!n & (nstarget > 1)) {
n = nstarget; /* avoid infinitue loop */
nstarget = nstarget*sr.rweight/minweight;
if (n == nstarget) break;
n = -1; /* moved target */
}
continue; /* try again */
}
if (xmit && ndp->thick != 0) /* need to offset origin? */
VSUM(sr.rorg, sr.rorg, ndp->pr->ron, -ndp->thick);
rayvalue(&sr); /* send & evaluate sample */
multcolor(sr.rcol, sr.rcoef);
addcolor(ndp->pr->rcol, sr.rcol);
++nsent;
}
return(nsent);
}
/* Sample non-diffuse components of BSDF */
static int
sample_sdf(BSDFDAT *ndp, int sflags)
{
int hasthru = (sflags == SDsampSpT &&
!(ndp->pr->crtype & (SPECULAR|AMBIENT))
&& bright(ndp->cthru) > FTINY);
int n, ntotal = 0;
double b = 0;
SDSpectralDF *dfp;
COLORV *unsc;
if (sflags == SDsampSpT) {
unsc = ndp->tunsamp;
if (ndp->pr->rod > 0)
dfp = (ndp->sd->tf != NULL) ? ndp->sd->tf : ndp->sd->tb;
else
dfp = (ndp->sd->tb != NULL) ? ndp->sd->tb : ndp->sd->tf;
} else /* sflags == SDsampSpR */ {
unsc = ndp->runsamp;
if (ndp->pr->rod > 0)
dfp = ndp->sd->rf;
else
dfp = ndp->sd->rb;
}
setcolor(unsc, 0, 0, 0);
if (dfp == NULL) /* no specular component? */
return(0);
if (hasthru) { /* separate view sample? */
RAY tr;
if (rayorigin(&tr, TRANS, ndp->pr, ndp->cthru) == 0) {
VCOPY(tr.rdir, ndp->pr->rdir);
rayvalue(&tr);
multcolor(tr.rcol, tr.rcoef);
addcolor(ndp->pr->rcol, tr.rcol);
ndp->pr->rxt = ndp->pr->rot + raydistance(&tr);
++ntotal;
b = bright(ndp->cthru);
} else
hasthru = 0;
}
if (dfp->maxHemi - b <= FTINY) { /* have specular to sample? */
b = 0;
} else {
FVECT vjit;
bsdf_jitter(vjit, ndp, ndp->sr_vpsa[1]);
b = SDdirectHemi(vjit, sflags, ndp->sd) - b;
if (b < 0) b = 0;
}
if (b <= specthresh+FTINY) { /* below sampling threshold? */
if (b > FTINY) { /* XXX no color from BSDF */
if (sflags == SDsampSpT) {
copycolor(unsc, ndp->pr->pcol);
scalecolor(unsc, b);
} else /* no pattern on reflection */
setcolor(unsc, b, b, b);
}
return(ntotal);
}
dimlist[ndims] = (int)(size_t)ndp->mp; /* else sample specular */
ndims += 2;
for (n = dfp->ncomp; n--; ) { /* loop over components */
dimlist[ndims-1] = n + 9438;
ntotal += sample_sdcomp(ndp, &dfp->comp[n], sflags==SDsampSpT);
}
ndims -= 2;
return(ntotal);
}
/* Color a ray that hit a BSDF material */
int
m_bsdf(OBJREC *m, RAY *r)
{
int hasthick = (m->otype == MAT_BSDF);
int hitfront;
COLOR ctmp;
SDError ec;
FVECT upvec, vtmp;
MFUNC *mf;
BSDFDAT nd;
/* check arguments */
if ((m->oargs.nsargs < hasthick+5) | (m->oargs.nfargs > 9) |
(m->oargs.nfargs % 3))
objerror(m, USER, "bad # arguments");
/* record surface struck */
hitfront = (r->rod > 0);
/* load cal file */
mf = hasthick ? getfunc(m, 5, 0x1d, 1)
: getfunc(m, 4, 0xe, 1) ;
setfunc(m, r);
nd.thick = 0; /* set thickness */
if (hasthick) {
nd.thick = evalue(mf->ep[0]);
if ((-FTINY <= nd.thick) & (nd.thick <= FTINY))
nd.thick = 0;
}
/* check backface visibility */
if (!hitfront & !backvis) {
raytrans(r);
return(1);
}
/* check other rays to pass */
if (nd.thick != 0 && (r->crtype & SHADOW ||
!(r->crtype & (SPECULAR|AMBIENT)) ||
(nd.thick > 0) ^ hitfront)) {
raytrans(r); /* hide our proxy */
return(1);
}
if (hasthick && r->crtype & SHADOW) /* early shadow check #1 */
return(1);
nd.mp = m;
nd.pr = r;
/* get BSDF data */
nd.sd = loadBSDF(m->oargs.sarg[hasthick]);
/* early shadow check #2 */
if (r->crtype & SHADOW && (nd.sd->tf == NULL) & (nd.sd->tb == NULL)) {
SDfreeCache(nd.sd);
return(1);
}
/* diffuse components */
if (hitfront) {
cvt_sdcolor(nd.rdiff, &nd.sd->rLambFront);
if (m->oargs.nfargs >= 3) {
setcolor(ctmp, m->oargs.farg[0],
m->oargs.farg[1],
m->oargs.farg[2]);
addcolor(nd.rdiff, ctmp);
}
cvt_sdcolor(nd.tdiff, &nd.sd->tLambFront);
} else {
cvt_sdcolor(nd.rdiff, &nd.sd->rLambBack);
if (m->oargs.nfargs >= 6) {
setcolor(ctmp, m->oargs.farg[3],
m->oargs.farg[4],
m->oargs.farg[5]);
addcolor(nd.rdiff, ctmp);
}
cvt_sdcolor(nd.tdiff, &nd.sd->tLambBack);
}
if (m->oargs.nfargs >= 9) { /* add diffuse transmittance? */
setcolor(ctmp, m->oargs.farg[6],
m->oargs.farg[7],
m->oargs.farg[8]);
addcolor(nd.tdiff, ctmp);
}
/* get modifiers */
raytexture(r, m->omod);
/* modify diffuse values */
multcolor(nd.rdiff, r->pcol);
multcolor(nd.tdiff, r->pcol);
/* get up vector */
upvec[0] = evalue(mf->ep[hasthick+0]);
upvec[1] = evalue(mf->ep[hasthick+1]);
upvec[2] = evalue(mf->ep[hasthick+2]);
/* return to world coords */
if (mf->fxp != &unitxf) {
multv3(upvec, upvec, mf->fxp->xfm);
nd.thick *= mf->fxp->sca;
}
if (r->rox != NULL) {
multv3(upvec, upvec, r->rox->f.xfm);
nd.thick *= r->rox->f.sca;
}
raynormal(nd.pnorm, r);
/* compute local BSDF xform */
ec = SDcompXform(nd.toloc, nd.pnorm, upvec);
if (!ec) {
nd.vray[0] = -r->rdir[0];
nd.vray[1] = -r->rdir[1];
nd.vray[2] = -r->rdir[2];
ec = SDmapDir(nd.vray, nd.toloc, nd.vray);
}
if (ec) {
objerror(m, WARNING, "Illegal orientation vector");
SDfreeCache(nd.sd);
return(1);
}
setcolor(nd.cthru, 0, 0, 0); /* consider through component */
setcolor(nd.cthru_surr, 0, 0, 0);
if (m->otype == MAT_ABSDF) {
compute_through(&nd);
if (r->crtype & SHADOW) {
RAY tr; /* attempt to pass shadow ray */
SDfreeCache(nd.sd);
if (rayorigin(&tr, TRANS, r, nd.cthru) < 0)
return(1); /* no through component */
VCOPY(tr.rdir, r->rdir);
rayvalue(&tr); /* transmit with scaling */
multcolor(tr.rcol, tr.rcoef);
copycolor(r->rcol, tr.rcol);
return(1); /* we're done */
}
}
ec = SDinvXform(nd.fromloc, nd.toloc);
if (!ec) /* determine BSDF resolution */
ec = SDsizeBSDF(nd.sr_vpsa, nd.vray, NULL,
SDqueryMin+SDqueryMax, nd.sd);
if (ec)
objerror(m, USER, transSDError(ec));
nd.sr_vpsa[0] = sqrt(nd.sr_vpsa[0]);
nd.sr_vpsa[1] = sqrt(nd.sr_vpsa[1]);
if (!hitfront) { /* perturb normal towards hit */
nd.pnorm[0] = -nd.pnorm[0];
nd.pnorm[1] = -nd.pnorm[1];
nd.pnorm[2] = -nd.pnorm[2];
}
/* sample reflection */
sample_sdf(&nd, SDsampSpR);
/* sample transmission */
sample_sdf(&nd, SDsampSpT);
/* compute indirect diffuse */
copycolor(ctmp, nd.rdiff);
addcolor(ctmp, nd.runsamp);
if (bright(ctmp) > FTINY) { /* ambient from reflection */
if (!hitfront)
flipsurface(r);
multambient(ctmp, r, nd.pnorm);
addcolor(r->rcol, ctmp);
if (!hitfront)
flipsurface(r);
}
copycolor(ctmp, nd.tdiff);
addcolor(ctmp, nd.tunsamp);
if (bright(ctmp) > FTINY) { /* ambient from other side */
FVECT bnorm;
if (hitfront)
flipsurface(r);
bnorm[0] = -nd.pnorm[0];
bnorm[1] = -nd.pnorm[1];
bnorm[2] = -nd.pnorm[2];
if (nd.thick != 0) { /* proxy with offset? */
VCOPY(vtmp, r->rop);
VSUM(r->rop, vtmp, r->ron, nd.thick);
multambient(ctmp, r, bnorm);
VCOPY(r->rop, vtmp);
} else
multambient(ctmp, r, bnorm);
addcolor(r->rcol, ctmp);
if (hitfront)
flipsurface(r);
}
/* add direct component */
if ((bright(nd.tdiff) <= FTINY) & (nd.sd->tf == NULL) &
(nd.sd->tb == NULL)) {
direct(r, dir_brdf, &nd); /* reflection only */
} else if (nd.thick == 0) {
direct(r, dir_bsdf, &nd); /* thin surface scattering */
} else {
direct(r, dir_brdf, &nd); /* reflection first */
VCOPY(vtmp, r->rop); /* offset for transmitted */
VSUM(r->rop, vtmp, r->ron, -nd.thick);
direct(r, dir_btdf, &nd); /* separate transmission */
VCOPY(r->rop, vtmp);
}
/* clean up */
SDfreeCache(nd.sd);
return(1);
}

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