src/rt/m_bsdf.c

#ifndef lint
static const char RCSid[] = "$Id: m_bsdf.c,v 2.6 2011/02/20 17:43:43 greg Exp $";
#endif
/*
 *  Shading for materials with BSDFs taken from XML data files
 */

#include "copyright.h"

#include  "ray.h"
#include  "ambient.h"
#include  "source.h"
#include  "func.h"
#include  "bsdf.h"
#include  "random.h"

/*
 *      Arguments to this material include optional diffuse colors.
 *  String arguments include the BSDF and function files.
 *      A non-zero thickness causes the strange but 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 if it has any
 *  non-diffuse transmission, making the BSDF surface invisible.  This
 *  shows the proxied geometry instead. Thickness has the further
 *  effect of turning off reflection on the hidden side so that 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.
 *      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 off.
 *      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_BSDF are:
 *      6+      thick   BSDFfile        ux uy uz        funcfile        transform
 *      0
 *      0|3|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 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;        /* sqrt of BSDF projected solid angle */
        RREAL   toloc[3][3];    /* world to local BSDF coords */
        RREAL   fromloc[3][3];  /* local BSDF coords to world */
        double  thick;          /* surface thickness */
        SDData  *sd;            /* loaded BSDF data */
        COLOR   runsamp;        /* BSDF hemispherical reflection */
        COLOR   rdiff;          /* added diffuse reflection */
        COLOR   tunsamp;        /* BSDF hemispherical transmission */
        COLOR   tdiff;          /* added diffuse transmission */
}  BSDFDAT;             /* BSDF material data */

#define cvt_sdcolor(cv, svp)    ccy2rgb(&(svp)->spec, (svp)->cieY, cv)

/* Jitter ray sample according to projected solid angle and specjitter */
static void
bsdf_jitter(FVECT vres, BSDFDAT *ndp)
{
        double  sr_psa = ndp->sr_vpsa;

        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);
}

/* Evaluate BSDF for direct component, returning true if OK to proceed */
static int
direct_bsdf_OK(COLOR cval, FVECT ldir, BSDFDAT *ndp)
{
        FVECT   vsrc, vjit;
        SDValue sv;
        SDError ec;
                                        /* transform source direction */
        if (SDmapDir(vsrc, ndp->toloc, ldir) != SDEnone)
                return(0);
                                        /* jitter query direction */
        bsdf_jitter(vjit, ndp);
                                        /* avoid indirect over-counting */
        if (ndp->thick != .0 && ndp->pr->crtype & (SPECULAR|AMBIENT) &&
                                vsrc[2] > .0 ^ vjit[2] > .0) {
                double  dx = vsrc[0] + vjit[0];
                double  dy = vsrc[1] + vjit[1];
                if (dx*dx + dy*dy <= ndp->sr_vpsa*ndp->sr_vpsa)
                        return(0);
        }
        ec = SDevalBSDF(&sv, vjit, vsrc, ndp->sd);
        if (ec)
                objerror(ndp->mp, USER, transSDError(ec));

        if (sv.cieY <= FTINY)           /* not worth using? */
                return(0);
                                        /* else we're good to go */
        cvt_sdcolor(cval, &sv);
        return(1);
}

/* 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 added 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 added diffuse transmission.
                 */
                copycolor(ctmp, np->tdiff);
                dtmp = -ldot * omega * (1.0/PI);
                scalecolor(ctmp, dtmp);
                addcolor(cval, ctmp);
        }
        /*
         *  Compute scattering coefficient using BSDF.
         */
        if (!direct_bsdf_OK(ctmp, ldir, np))
                return;
        if (ldot > .0) {                /* pattern only diffuse reflection */
                COLOR   ctmp1, ctmp2;
                dtmp = (np->pr->rod > .0) ? np->sd->rLambFront.cieY
                                        : np->sd->rLambBack.cieY;
                                        /* diffuse fraction */
                dtmp /= PI * bright(ctmp);
                copycolor(ctmp2, np->pr->pcol);
                scalecolor(ctmp2, dtmp);
                setcolor(ctmp1, 1.-dtmp, 1.-dtmp, 1.-dtmp);
                addcolor(ctmp1, ctmp2);
                multcolor(ctmp, ctmp1); /* apply derated pattern */
                dtmp = ldot * omega;
        } else {                        /* full pattern on transmission */
                multcolor(ctmp, np->pr->pcol);
                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 added diffuse reflected component.
                 */
                copycolor(ctmp, np->rdiff);
                dtmp = ldot * omega * (1./PI);
                scalecolor(ctmp, dtmp);
                addcolor(cval, ctmp);
        }
        /*
         *  Compute reflection coefficient using BSDF.
         */
        if (!direct_bsdf_OK(ctmp, ldir, np))
                return;
                                        /* pattern only diffuse reflection */
        dtmp = (np->pr->rod > .0) ? np->sd->rLambFront.cieY
                                : np->sd->rLambBack.cieY;
        dtmp /= PI * bright(ctmp);      /* diffuse fraction */
        copycolor(ctmp2, np->pr->pcol);
        scalecolor(ctmp2, dtmp);
        setcolor(ctmp1, 1.-dtmp, 1.-dtmp, 1.-dtmp);
        addcolor(ctmp1, ctmp2);
        multcolor(ctmp, ctmp1);         /* apply derated pattern */
        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 added diffuse transmission.
                 */
                copycolor(ctmp, np->tdiff);
                dtmp = -ldot * omega * (1.0/PI);
                scalecolor(ctmp, dtmp);
                addcolor(cval, ctmp);
        }
        /*
         *  Compute scattering coefficient using BSDF.
         */
        if (!direct_bsdf_OK(ctmp, ldir, 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 usepat)
{
        int     nstarget = 1;
        int     nsent = 0;
        SDError ec;
        SDValue bsv;
        double  sthick;
        FVECT   vjit, vsmp;
        RAY     sr;
        int     ntrials;
                                                /* multiple samples? */
        if (specjitter > 1.5) {
                nstarget = specjitter*ndp->pr->rweight + .5;
                if (nstarget < 1)
                        nstarget = 1;
        }
                                                /* run through our trials */
        for (ntrials = 0; nsent < nstarget && ntrials < 9*nstarget; ntrials++) {
                SDerrorDetail[0] = '\0';
                                                /* sample direction & coef. */
                bsdf_jitter(vjit, ndp);
                ec = SDsampComponent(&bsv, vsmp, vjit, ntrials ? frandom()
                                : urand(ilhash(dimlist,ndims)+samplendx), dcp);
                if (ec)
                        objerror(ndp->mp, USER, transSDError(ec));
                                                /* zero component? */
                if (bsv.cieY <= FTINY)
                        break;
                                                /* map vector to world */
                if (SDmapDir(sr.rdir, ndp->fromloc, vsmp) != SDEnone)
                        break;
                                                /* unintentional penetration? */
                if (DOT(sr.rdir, ndp->pr->ron) > .0 ^ vsmp[2] > .0)
                        continue;
                                                /* spawn a specular ray */
                if (nstarget > 1)
                        bsv.cieY /= (double)nstarget;
                cvt_sdcolor(sr.rcoef, &bsv);    /* use color */
                if (usepat)                     /* pattern on transmission */
                        multcolor(sr.rcoef, ndp->pr->pcol);
                if (rayorigin(&sr, SPECULAR, ndp->pr, sr.rcoef) < 0) {
                        if (maxdepth  > 0)
                                break;
                        ++nsent;                /* Russian roulette victim */
                        continue;
                }
                                                /* need to offset origin? */
                if (ndp->thick != .0 && ndp->pr->rod > .0 ^ vsmp[2] > .0)
                        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             n, ntotal = 0;
        SDSpectralDF    *dfp;
        COLORV          *unsc;

        if (sflags == SDsampSpT) {
                unsc = ndp->tunsamp;
                dfp = ndp->sd->tf;
                cvt_sdcolor(unsc, &ndp->sd->tLamb);
        } else /* sflags == SDsampSpR */ {
                unsc = ndp->runsamp;
                if (ndp->pr->rod > .0) {
                        dfp = ndp->sd->rf;
                        cvt_sdcolor(unsc, &ndp->sd->rLambFront);
                } else {
                        dfp = ndp->sd->rb;
                        cvt_sdcolor(unsc, &ndp->sd->rLambBack);
                }
        }
        multcolor(unsc, ndp->pr->pcol);
        if (dfp == NULL)                        /* no specular component? */
                return(0);
                                                /* below sampling threshold? */
        if (dfp->maxHemi <= specthresh+FTINY) {
                if (dfp->maxHemi > FTINY) {     /* XXX no color from BSDF */
                        FVECT   vjit;
                        double  d;
                        COLOR   ctmp;
                        bsdf_jitter(vjit, ndp);
                        d = SDdirectHemi(vjit, sflags, ndp->sd);
                        if (sflags == SDsampSpT) {
                                copycolor(ctmp, ndp->pr->pcol);
                                scalecolor(ctmp, d);
                        } else                  /* no pattern on reflection */
                                setcolor(ctmp, d, d, d);
                        addcolor(unsc, ctmp);
                }
                return(0);
        }
                                                /* else need to sample */
        dimlist[ndims++] = (int)(size_t)ndp->mp;
        ndims++;
        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     hitfront;
        COLOR   ctmp;
        SDError ec;
        FVECT   upvec, vtmp;
        MFUNC   *mf;
        BSDFDAT nd;
                                                /* check arguments */
        if ((m->oargs.nsargs < 6) | (m->oargs.nfargs > 9) |
                                (m->oargs.nfargs % 3))
                objerror(m, USER, "bad # arguments");
                                                /* record surface struck */
        hitfront = (r->rod > .0);
                                                /* load cal file */
        mf = getfunc(m, 5, 0x1d, 1);
                                                /* get thickness */
        nd.thick = evalue(mf->ep[0]);
        if ((-FTINY <= nd.thick) & (nd.thick <= FTINY))
                nd.thick = .0;
                                                /* check shadow */
        if (r->crtype & SHADOW) {
                if (nd.thick != .0)
                        raytrans(r);            /* pass-through */
                return(1);                      /* or shadow */
        }
                                                /* check other rays to pass */
        if (nd.thick != .0 && (!(r->crtype & (SPECULAR|AMBIENT)) ||
                                nd.thick > .0 ^ hitfront)) {
                raytrans(r);                    /* hide our proxy */
                return(1);
        }
                                                /* get BSDF data */
        nd.sd = loadBSDF(m->oargs.sarg[1]);
                                                /* diffuse reflectance */
        if (hitfront) {
                if (m->oargs.nfargs < 3)
                        setcolor(nd.rdiff, .0, .0, .0);
                else
                        setcolor(nd.rdiff, m->oargs.farg[0],
                                        m->oargs.farg[1],
                                        m->oargs.farg[2]);
        } else {
                if (m->oargs.nfargs < 6) {      /* check invisible backside */
                        if (!backvis && (nd.sd->rb == NULL) &
                                                (nd.sd->tf == NULL)) {
                                SDfreeCache(nd.sd);
                                raytrans(r);
                                return(1);
                        }
                        setcolor(nd.rdiff, .0, .0, .0);
                } else
                        setcolor(nd.rdiff, m->oargs.farg[3],
                                        m->oargs.farg[4],
                                        m->oargs.farg[5]);
        }
                                                /* diffuse transmittance */
        if (m->oargs.nfargs < 9)
                setcolor(nd.tdiff, .0, .0, .0);
        else
                setcolor(nd.tdiff, m->oargs.farg[6],
                                m->oargs.farg[7],
                                m->oargs.farg[8]);
        nd.mp = m;
        nd.pr = r;
                                                /* 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[1]);
        upvec[1] = evalue(mf->ep[2]);
        upvec[2] = evalue(mf->ep[3]);
                                                /* return to world coords */
        if (mf->f != &unitxf) {
                multv3(upvec, upvec, mf->f->xfm);
                nd.thick *= mf->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)
                ec = SDinvXform(nd.fromloc, nd.toloc);
                                                /* determine BSDF resolution */
        if (!ec)
                ec = SDsizeBSDF(&nd.sr_vpsa, nd.vray, SDqueryMin, nd.sd);
        if (!ec)
                nd.sr_vpsa = sqrt(nd.sr_vpsa);
        else {
                objerror(m, WARNING, transSDError(ec));
                SDfreeCache(nd.sd);
                return(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)) {
                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);
}
Revision:	2.7
Committed:	Tue Feb 22 05:41:02 2011 UTC (14 years, 8 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.6:	+39 -43 lines
Log Message:	Fixed problem with double-counting through component in indirect
#	User	Rev	Content
1	greg	2.1	#ifndef lint
2	greg	2.7	static const char RCSid[] = "$Id: m_bsdf.c,v 2.6 2011/02/20 17:43:43 greg Exp $";
3	greg	2.1	#endif
4			/*
5			* Shading for materials with BSDFs taken from XML data files
6			*/
7
8			#include "copyright.h"
9
10			#include "ray.h"
11			#include "ambient.h"
12			#include "source.h"
13			#include "func.h"
14			#include "bsdf.h"
15			#include "random.h"
16
17			/*
18			* Arguments to this material include optional diffuse colors.
19			* String arguments include the BSDF and function files.
20	greg	2.5	* A non-zero thickness causes the strange but useful behavior
21			* of translating transmitted rays this distance beneath the surface
22			* (opposite the surface normal) to bypass any intervening geometry.
23			* Translation only affects scattered, non-source-directed samples.
24			* A non-zero thickness has the further side-effect that an unscattered
25	greg	2.1	* (view) ray will pass right through our material if it has any
26	greg	2.5	* non-diffuse transmission, making the BSDF surface invisible. This
27			* shows the proxied geometry instead. Thickness has the further
28			* effect of turning off reflection on the hidden side so that rays
29			* heading in the opposite direction pass unimpeded through the BSDF
30			* surface. A paired surface may be placed on the opposide side of
31			* the detail geometry, less than this thickness away, if a two-way
32			* proxy is desired. Note that the sign of the thickness is important.
33			* A positive thickness hides geometry behind the BSDF surface and uses
34			* front reflectance and transmission properties. A negative thickness
35			* hides geometry in front of the surface when rays hit from behind,
36			* and applies only the transmission and backside reflectance properties.
37			* Reflection is ignored on the hidden side, as those rays pass through.
38	greg	2.1	* The "up" vector for the BSDF is given by three variables, defined
39			* (along with the thickness) by the named function file, or '.' if none.
40			* Together with the surface normal, this defines the local coordinate
41			* system for the BSDF.
42			* We do not reorient the surface, so if the BSDF has no back-side
43	greg	2.5	* reflectance and none is given in the real arguments, a BSDF surface
44			* with zero thickness will appear black when viewed from behind
45			* unless backface visibility is off.
46			* The diffuse arguments are added to components in the BSDF file,
47	greg	2.1	* not multiplied. However, patterns affect this material as a multiplier
48			* on everything except non-diffuse reflection.
49			*
50			* Arguments for MAT_BSDF are:
51			* 6+ thick BSDFfile ux uy uz funcfile transform
52			* 0
53			* 0\|3\|9 rdf gdf bdf
54			* rdb gdb bdb
55			* rdt gdt bdt
56			*/
57
58	greg	2.4	/*
59			* Note that our reverse ray-tracing process means that the positions
60			* of incoming and outgoing vectors may be reversed in our calls
61			* to the BSDF library. This is fine, since the bidirectional nature
62			* of the BSDF (that's what the 'B' stands for) means it all works out.
63			*/
64
65	greg	2.1	typedef struct {
66			OBJREC mp; / material pointer */
67			RAY pr; / intersected ray */
68			FVECT pnorm; /* perturbed surface normal */
69	greg	2.4	FVECT vray; /* local outgoing (return) vector */
70			double sr_vpsa; /* sqrt of BSDF projected solid angle */
71	greg	2.1	RREAL toloc[3][3]; /* world to local BSDF coords */
72			RREAL fromloc[3][3]; /* local BSDF coords to world */
73			double thick; /* surface thickness */
74			SDData sd; / loaded BSDF data */
75			COLOR runsamp; /* BSDF hemispherical reflection */
76			COLOR rdiff; /* added diffuse reflection */
77			COLOR tunsamp; /* BSDF hemispherical transmission */
78			COLOR tdiff; /* added diffuse transmission */
79			} BSDFDAT; /* BSDF material data */
80
81			#define cvt_sdcolor(cv, svp) ccy2rgb(&(svp)->spec, (svp)->cieY, cv)
82
83	greg	2.4	/* Jitter ray sample according to projected solid angle and specjitter */
84			static void
85			bsdf_jitter(FVECT vres, BSDFDAT *ndp)
86			{
87			double sr_psa = ndp->sr_vpsa;
88
89			VCOPY(vres, ndp->vray);
90			if (specjitter < 1.)
91			sr_psa *= specjitter;
92			if (sr_psa <= FTINY)
93			return;
94			vres[0] += sr_psa*(.5 - frandom());
95			vres[1] += sr_psa*(.5 - frandom());
96			normalize(vres);
97			}
98
99	greg	2.7	/* Evaluate BSDF for direct component, returning true if OK to proceed */
100			static int
101			direct_bsdf_OK(COLOR cval, FVECT ldir, BSDFDAT *ndp)
102			{
103			FVECT vsrc, vjit;
104			SDValue sv;
105			SDError ec;
106			/* transform source direction */
107			if (SDmapDir(vsrc, ndp->toloc, ldir) != SDEnone)
108			return(0);
109			/* jitter query direction */
110			bsdf_jitter(vjit, ndp);
111			/* avoid indirect over-counting */
112			if (ndp->thick != .0 && ndp->pr->crtype & (SPECULAR\|AMBIENT) &&
113			vsrc[2] > .0 ^ vjit[2] > .0) {
114			double dx = vsrc[0] + vjit[0];
115			double dy = vsrc[1] + vjit[1];
116			if (dxdx + dydy <= ndp->sr_vpsa*ndp->sr_vpsa)
117			return(0);
118			}
119			ec = SDevalBSDF(&sv, vjit, vsrc, ndp->sd);
120			if (ec)
121			objerror(ndp->mp, USER, transSDError(ec));
122
123			if (sv.cieY <= FTINY) /* not worth using? */
124			return(0);
125			/* else we're good to go */
126			cvt_sdcolor(cval, &sv);
127			return(1);
128			}
129
130	greg	2.5	/* Compute source contribution for BSDF (reflected & transmitted) */
131	greg	2.1	static void
132	greg	2.5	dir_bsdf(
133	greg	2.1	COLOR cval, /* returned coefficient */
134			void nnp, / material data */
135			FVECT ldir, /* light source direction */
136			double omega /* light source size */
137			)
138			{
139	greg	2.3	BSDFDAT np = (BSDFDAT )nnp;
140	greg	2.1	double ldot;
141			double dtmp;
142			COLOR ctmp;
143
144			setcolor(cval, .0, .0, .0);
145
146			ldot = DOT(np->pnorm, ldir);
147			if ((-FTINY <= ldot) & (ldot <= FTINY))
148			return;
149
150			if (ldot > .0 && bright(np->rdiff) > FTINY) {
151			/*
152			* Compute added diffuse reflected component.
153			*/
154			copycolor(ctmp, np->rdiff);
155			dtmp = ldot * omega * (1./PI);
156			scalecolor(ctmp, dtmp);
157			addcolor(cval, ctmp);
158			}
159			if (ldot < .0 && bright(np->tdiff) > FTINY) {
160			/*
161			* Compute added diffuse transmission.
162			*/
163			copycolor(ctmp, np->tdiff);
164			dtmp = -ldot * omega * (1.0/PI);
165			scalecolor(ctmp, dtmp);
166			addcolor(cval, ctmp);
167			}
168			/*
169			* Compute scattering coefficient using BSDF.
170			*/
171	greg	2.7	if (!direct_bsdf_OK(ctmp, ldir, np))
172	greg	2.1	return;
173			if (ldot > .0) { /* pattern only diffuse reflection */
174			COLOR ctmp1, ctmp2;
175			dtmp = (np->pr->rod > .0) ? np->sd->rLambFront.cieY
176			: np->sd->rLambBack.cieY;
177	greg	2.7	/* diffuse fraction */
178			dtmp /= PI * bright(ctmp);
179	greg	2.1	copycolor(ctmp2, np->pr->pcol);
180			scalecolor(ctmp2, dtmp);
181			setcolor(ctmp1, 1.-dtmp, 1.-dtmp, 1.-dtmp);
182			addcolor(ctmp1, ctmp2);
183	greg	2.3	multcolor(ctmp, ctmp1); /* apply derated pattern */
184	greg	2.1	dtmp = ldot * omega;
185			} else { /* full pattern on transmission */
186			multcolor(ctmp, np->pr->pcol);
187			dtmp = -ldot * omega;
188			}
189			scalecolor(ctmp, dtmp);
190			addcolor(cval, ctmp);
191			}
192
193	greg	2.5	/* Compute source contribution for BSDF (reflected only) */
194			static void
195			dir_brdf(
196			COLOR cval, /* returned coefficient */
197			void nnp, / material data */
198			FVECT ldir, /* light source direction */
199			double omega /* light source size */
200			)
201			{
202			BSDFDAT np = (BSDFDAT )nnp;
203			double ldot;
204			double dtmp;
205			COLOR ctmp, ctmp1, ctmp2;
206
207			setcolor(cval, .0, .0, .0);
208
209			ldot = DOT(np->pnorm, ldir);
210
211			if (ldot <= FTINY)
212			return;
213
214			if (bright(np->rdiff) > FTINY) {
215			/*
216			* Compute added diffuse reflected component.
217			*/
218			copycolor(ctmp, np->rdiff);
219			dtmp = ldot * omega * (1./PI);
220			scalecolor(ctmp, dtmp);
221			addcolor(cval, ctmp);
222			}
223			/*
224			* Compute reflection coefficient using BSDF.
225			*/
226	greg	2.7	if (!direct_bsdf_OK(ctmp, ldir, np))
227	greg	2.5	return;
228			/* pattern only diffuse reflection */
229			dtmp = (np->pr->rod > .0) ? np->sd->rLambFront.cieY
230			: np->sd->rLambBack.cieY;
231	greg	2.7	dtmp /= PI * bright(ctmp); /* diffuse fraction */
232	greg	2.5	copycolor(ctmp2, np->pr->pcol);
233			scalecolor(ctmp2, dtmp);
234			setcolor(ctmp1, 1.-dtmp, 1.-dtmp, 1.-dtmp);
235			addcolor(ctmp1, ctmp2);
236			multcolor(ctmp, ctmp1); /* apply derated pattern */
237			dtmp = ldot * omega;
238			scalecolor(ctmp, dtmp);
239			addcolor(cval, ctmp);
240			}
241
242			/* Compute source contribution for BSDF (transmitted only) */
243			static void
244			dir_btdf(
245			COLOR cval, /* returned coefficient */
246			void nnp, / material data */
247			FVECT ldir, /* light source direction */
248			double omega /* light source size */
249			)
250			{
251			BSDFDAT np = (BSDFDAT )nnp;
252			double ldot;
253			double dtmp;
254			COLOR ctmp;
255
256			setcolor(cval, .0, .0, .0);
257
258			ldot = DOT(np->pnorm, ldir);
259
260			if (ldot >= -FTINY)
261			return;
262
263			if (bright(np->tdiff) > FTINY) {
264			/*
265			* Compute added diffuse transmission.
266			*/
267			copycolor(ctmp, np->tdiff);
268			dtmp = -ldot * omega * (1.0/PI);
269			scalecolor(ctmp, dtmp);
270			addcolor(cval, ctmp);
271			}
272			/*
273			* Compute scattering coefficient using BSDF.
274			*/
275	greg	2.7	if (!direct_bsdf_OK(ctmp, ldir, np))
276	greg	2.5	return;
277			/* full pattern on transmission */
278			multcolor(ctmp, np->pr->pcol);
279			dtmp = -ldot * omega;
280			scalecolor(ctmp, dtmp);
281			addcolor(cval, ctmp);
282			}
283
284	greg	2.1	/* Sample separate BSDF component */
285			static int
286			sample_sdcomp(BSDFDAT ndp, SDComponent dcp, int usepat)
287			{
288			int nstarget = 1;
289			int nsent = 0;
290			SDError ec;
291			SDValue bsv;
292			double sthick;
293	greg	2.4	FVECT vjit, vsmp;
294	greg	2.1	RAY sr;
295			int ntrials;
296			/* multiple samples? */
297			if (specjitter > 1.5) {
298			nstarget = specjitter*ndp->pr->rweight + .5;
299			if (nstarget < 1)
300			nstarget = 1;
301			}
302			/* run through our trials */
303			for (ntrials = 0; nsent < nstarget && ntrials < 9*nstarget; ntrials++) {
304			SDerrorDetail[0] = '\0';
305			/* sample direction & coef. */
306	greg	2.4	bsdf_jitter(vjit, ndp);
307			ec = SDsampComponent(&bsv, vsmp, vjit, ntrials ? frandom()
308			: urand(ilhash(dimlist,ndims)+samplendx), dcp);
309	greg	2.1	if (ec)
310	greg	2.2	objerror(ndp->mp, USER, transSDError(ec));
311	greg	2.1	/* zero component? */
312			if (bsv.cieY <= FTINY)
313			break;
314			/* map vector to world */
315	greg	2.4	if (SDmapDir(sr.rdir, ndp->fromloc, vsmp) != SDEnone)
316	greg	2.1	break;
317			/* unintentional penetration? */
318	greg	2.4	if (DOT(sr.rdir, ndp->pr->ron) > .0 ^ vsmp[2] > .0)
319	greg	2.1	continue;
320			/* spawn a specular ray */
321			if (nstarget > 1)
322			bsv.cieY /= (double)nstarget;
323			cvt_sdcolor(sr.rcoef, &bsv); /* use color */
324			if (usepat) /* pattern on transmission */
325			multcolor(sr.rcoef, ndp->pr->pcol);
326			if (rayorigin(&sr, SPECULAR, ndp->pr, sr.rcoef) < 0) {
327			if (maxdepth > 0)
328			break;
329			++nsent; /* Russian roulette victim */
330			continue;
331			}
332	greg	2.5	/* need to offset origin? */
333			if (ndp->thick != .0 && ndp->pr->rod > .0 ^ vsmp[2] > .0)
334			VSUM(sr.rorg, sr.rorg, ndp->pr->ron, -ndp->thick);
335	greg	2.1	rayvalue(&sr); /* send & evaluate sample */
336			multcolor(sr.rcol, sr.rcoef);
337			addcolor(ndp->pr->rcol, sr.rcol);
338			++nsent;
339			}
340			return(nsent);
341			}
342
343			/* Sample non-diffuse components of BSDF */
344			static int
345			sample_sdf(BSDFDAT *ndp, int sflags)
346			{
347			int n, ntotal = 0;
348			SDSpectralDF *dfp;
349			COLORV *unsc;
350
351			if (sflags == SDsampSpT) {
352			unsc = ndp->tunsamp;
353			dfp = ndp->sd->tf;
354			cvt_sdcolor(unsc, &ndp->sd->tLamb);
355			} else /* sflags == SDsampSpR */ {
356			unsc = ndp->runsamp;
357			if (ndp->pr->rod > .0) {
358			dfp = ndp->sd->rf;
359			cvt_sdcolor(unsc, &ndp->sd->rLambFront);
360			} else {
361			dfp = ndp->sd->rb;
362			cvt_sdcolor(unsc, &ndp->sd->rLambBack);
363			}
364			}
365			multcolor(unsc, ndp->pr->pcol);
366			if (dfp == NULL) /* no specular component? */
367			return(0);
368			/* below sampling threshold? */
369			if (dfp->maxHemi <= specthresh+FTINY) {
370	greg	2.3	if (dfp->maxHemi > FTINY) { /* XXX no color from BSDF */
371	greg	2.4	FVECT vjit;
372			double d;
373	greg	2.1	COLOR ctmp;
374	greg	2.4	bsdf_jitter(vjit, ndp);
375			d = SDdirectHemi(vjit, sflags, ndp->sd);
376	greg	2.1	if (sflags == SDsampSpT) {
377			copycolor(ctmp, ndp->pr->pcol);
378			scalecolor(ctmp, d);
379			} else /* no pattern on reflection */
380			setcolor(ctmp, d, d, d);
381			addcolor(unsc, ctmp);
382			}
383			return(0);
384			}
385			/* else need to sample */
386			dimlist[ndims++] = (int)(size_t)ndp->mp;
387			ndims++;
388			for (n = dfp->ncomp; n--; ) { /* loop over components */
389			dimlist[ndims-1] = n + 9438;
390			ntotal += sample_sdcomp(ndp, &dfp->comp[n], sflags==SDsampSpT);
391			}
392			ndims -= 2;
393			return(ntotal);
394			}
395
396			/* Color a ray that hit a BSDF material */
397			int
398			m_bsdf(OBJREC m, RAY r)
399			{
400	greg	2.6	int hitfront;
401	greg	2.1	COLOR ctmp;
402			SDError ec;
403	greg	2.5	FVECT upvec, vtmp;
404	greg	2.1	MFUNC *mf;
405			BSDFDAT nd;
406			/* check arguments */
407			if ((m->oargs.nsargs < 6) \| (m->oargs.nfargs > 9) \|
408			(m->oargs.nfargs % 3))
409			objerror(m, USER, "bad # arguments");
410	greg	2.6	/* record surface struck */
411			hitfront = (r->rod > .0);
412	greg	2.1	/* load cal file */
413			mf = getfunc(m, 5, 0x1d, 1);
414			/* get thickness */
415			nd.thick = evalue(mf->ep[0]);
416	greg	2.5	if ((-FTINY <= nd.thick) & (nd.thick <= FTINY))
417	greg	2.1	nd.thick = .0;
418			/* check shadow */
419			if (r->crtype & SHADOW) {
420	greg	2.5	if (nd.thick != .0)
421	greg	2.3	raytrans(r); /* pass-through */
422	greg	2.5	return(1); /* or shadow */
423	greg	2.1	}
424	greg	2.5	/* check other rays to pass */
425	greg	2.7	if (nd.thick != .0 && (!(r->crtype & (SPECULAR\|AMBIENT)) \|\|
426	greg	2.6	nd.thick > .0 ^ hitfront)) {
427	greg	2.5	raytrans(r); /* hide our proxy */
428	greg	2.1	return(1);
429			}
430	greg	2.5	/* get BSDF data */
431			nd.sd = loadBSDF(m->oargs.sarg[1]);
432	greg	2.1	/* diffuse reflectance */
433	greg	2.6	if (hitfront) {
434	greg	2.1	if (m->oargs.nfargs < 3)
435			setcolor(nd.rdiff, .0, .0, .0);
436			else
437			setcolor(nd.rdiff, m->oargs.farg[0],
438			m->oargs.farg[1],
439			m->oargs.farg[2]);
440			} else {
441			if (m->oargs.nfargs < 6) { /* check invisible backside */
442	greg	2.3	if (!backvis && (nd.sd->rb == NULL) &
443			(nd.sd->tf == NULL)) {
444	greg	2.1	SDfreeCache(nd.sd);
445			raytrans(r);
446			return(1);
447			}
448			setcolor(nd.rdiff, .0, .0, .0);
449			} else
450			setcolor(nd.rdiff, m->oargs.farg[3],
451			m->oargs.farg[4],
452			m->oargs.farg[5]);
453			}
454			/* diffuse transmittance */
455			if (m->oargs.nfargs < 9)
456			setcolor(nd.tdiff, .0, .0, .0);
457			else
458			setcolor(nd.tdiff, m->oargs.farg[6],
459			m->oargs.farg[7],
460			m->oargs.farg[8]);
461			nd.mp = m;
462			nd.pr = r;
463			/* get modifiers */
464			raytexture(r, m->omod);
465			/* modify diffuse values */
466			multcolor(nd.rdiff, r->pcol);
467			multcolor(nd.tdiff, r->pcol);
468			/* get up vector */
469			upvec[0] = evalue(mf->ep[1]);
470			upvec[1] = evalue(mf->ep[2]);
471			upvec[2] = evalue(mf->ep[3]);
472			/* return to world coords */
473			if (mf->f != &unitxf) {
474			multv3(upvec, upvec, mf->f->xfm);
475			nd.thick *= mf->f->sca;
476			}
477			raynormal(nd.pnorm, r);
478			/* compute local BSDF xform */
479			ec = SDcompXform(nd.toloc, nd.pnorm, upvec);
480			if (!ec) {
481	greg	2.4	nd.vray[0] = -r->rdir[0];
482			nd.vray[1] = -r->rdir[1];
483			nd.vray[2] = -r->rdir[2];
484			ec = SDmapDir(nd.vray, nd.toloc, nd.vray);
485	greg	2.1	}
486			if (!ec)
487			ec = SDinvXform(nd.fromloc, nd.toloc);
488	greg	2.4	/* determine BSDF resolution */
489			if (!ec)
490			ec = SDsizeBSDF(&nd.sr_vpsa, nd.vray, SDqueryMin, nd.sd);
491			if (!ec)
492			nd.sr_vpsa = sqrt(nd.sr_vpsa);
493			else {
494	greg	2.2	objerror(m, WARNING, transSDError(ec));
495	greg	2.1	SDfreeCache(nd.sd);
496			return(1);
497			}
498	greg	2.6	if (!hitfront) { /* perturb normal towards hit */
499	greg	2.1	nd.pnorm[0] = -nd.pnorm[0];
500			nd.pnorm[1] = -nd.pnorm[1];
501			nd.pnorm[2] = -nd.pnorm[2];
502			}
503			/* sample reflection */
504			sample_sdf(&nd, SDsampSpR);
505			/* sample transmission */
506			sample_sdf(&nd, SDsampSpT);
507			/* compute indirect diffuse */
508			copycolor(ctmp, nd.rdiff);
509			addcolor(ctmp, nd.runsamp);
510	greg	2.5	if (bright(ctmp) > FTINY) { /* ambient from reflection */
511	greg	2.6	if (!hitfront)
512	greg	2.1	flipsurface(r);
513			multambient(ctmp, r, nd.pnorm);
514			addcolor(r->rcol, ctmp);
515	greg	2.6	if (!hitfront)
516	greg	2.1	flipsurface(r);
517			}
518			copycolor(ctmp, nd.tdiff);
519			addcolor(ctmp, nd.tunsamp);
520			if (bright(ctmp) > FTINY) { /* ambient from other side */
521			FVECT bnorm;
522	greg	2.6	if (hitfront)
523	greg	2.1	flipsurface(r);
524			bnorm[0] = -nd.pnorm[0];
525			bnorm[1] = -nd.pnorm[1];
526			bnorm[2] = -nd.pnorm[2];
527	greg	2.5	if (nd.thick != .0) { /* proxy with offset? */
528			VCOPY(vtmp, r->rop);
529			VSUM(r->rop, vtmp, r->ron, -nd.thick);
530			multambient(ctmp, r, bnorm);
531			VCOPY(r->rop, vtmp);
532			} else
533			multambient(ctmp, r, bnorm);
534	greg	2.1	addcolor(r->rcol, ctmp);
535	greg	2.6	if (hitfront)
536	greg	2.1	flipsurface(r);
537			}
538			/* add direct component */
539	greg	2.5	if ((bright(nd.tdiff) <= FTINY) & (nd.sd->tf == NULL)) {
540			direct(r, dir_brdf, &nd); /* reflection only */
541			} else if (nd.thick == .0) {
542			direct(r, dir_bsdf, &nd); /* thin surface scattering */
543			} else {
544			direct(r, dir_brdf, &nd); /* reflection first */
545			VCOPY(vtmp, r->rop); /* offset for transmitted */
546			VSUM(r->rop, vtmp, r->ron, -nd.thick);
547	greg	2.6	direct(r, dir_btdf, &nd); /* separate transmission */
548	greg	2.5	VCOPY(r->rop, vtmp);
549			}
550	greg	2.1	/* clean up */
551			SDfreeCache(nd.sd);
552			return(1);
553			}