src/rt/m_bsdf.c

#ifndef lint
static const char RCSid[] = "$Id: m_bsdf.c,v 2.9 2011/04/19 21:31:22 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|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 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 */
        double  thru_psa;       /* through direction 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, int domax)
{
        double  sr_psa = ndp->sr_vpsa[domax];

        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, 0);
                                        /* 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->thru_psa)
                        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   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(vsmp, ndp, 0);
                ec = SDsampComponent(&bsv, vsmp, 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, 1);
                        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, NULL,
                                                SDqueryMin+SDqueryMax, nd.sd);
        nd.thru_psa = .0;
        if (!ec && nd.thick != 0 && r->crtype & (SPECULAR|AMBIENT)) {
                FVECT   vthru;
                vthru[0] = -nd.vray[0];
                vthru[1] = -nd.vray[1];
                vthru[2] = -nd.vray[2];
                ec = SDsizeBSDF(&nd.thru_psa, nd.vray, vthru,
                                                SDqueryMin, nd.sd);
        }
        if (ec) {
                objerror(m, WARNING, transSDError(ec));
                SDfreeCache(nd.sd);
                return(1);
        }
        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)) {
                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:	2.10
Committed:	Sun Apr 24 19:39:21 2011 UTC (13 years, 6 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.9:	+4 -4 lines
Log Message:	Partial implementation of variable-resolution BSDFs
#	User	Rev	Content
1	greg	2.1	#ifndef lint
2	greg	2.10	static const char RCSid[] = "$Id: m_bsdf.c,v 2.9 2011/04/19 21:31:22 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	greg	2.8	* 0\|3\|6\|9 rdf gdf bdf
54	greg	2.1	* 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	greg	2.9	double sr_vpsa[2]; /* sqrt of BSDF projected solid angle extrema */
71			double thru_psa; /* through direction projected solid angle */
72	greg	2.1	RREAL toloc[3][3]; /* world to local BSDF coords */
73			RREAL fromloc[3][3]; /* local BSDF coords to world */
74			double thick; /* surface thickness */
75			SDData sd; / loaded BSDF data */
76			COLOR runsamp; /* BSDF hemispherical reflection */
77			COLOR rdiff; /* added diffuse reflection */
78			COLOR tunsamp; /* BSDF hemispherical transmission */
79			COLOR tdiff; /* added diffuse transmission */
80			} BSDFDAT; /* BSDF material data */
81
82			#define cvt_sdcolor(cv, svp) ccy2rgb(&(svp)->spec, (svp)->cieY, cv)
83
84	greg	2.4	/* Jitter ray sample according to projected solid angle and specjitter */
85			static void
86	greg	2.9	bsdf_jitter(FVECT vres, BSDFDAT *ndp, int domax)
87	greg	2.4	{
88	greg	2.9	double sr_psa = ndp->sr_vpsa[domax];
89	greg	2.4
90			VCOPY(vres, ndp->vray);
91			if (specjitter < 1.)
92			sr_psa *= specjitter;
93			if (sr_psa <= FTINY)
94			return;
95			vres[0] += sr_psa*(.5 - frandom());
96			vres[1] += sr_psa*(.5 - frandom());
97			normalize(vres);
98			}
99
100	greg	2.7	/* Evaluate BSDF for direct component, returning true if OK to proceed */
101			static int
102			direct_bsdf_OK(COLOR cval, FVECT ldir, BSDFDAT *ndp)
103			{
104			FVECT vsrc, vjit;
105			SDValue sv;
106			SDError ec;
107			/* transform source direction */
108			if (SDmapDir(vsrc, ndp->toloc, ldir) != SDEnone)
109			return(0);
110			/* jitter query direction */
111	greg	2.9	bsdf_jitter(vjit, ndp, 0);
112	greg	2.7	/* avoid indirect over-counting */
113	greg	2.9	if (ndp->thick != 0 && ndp->pr->crtype & (SPECULAR\|AMBIENT) &&
114			vsrc[2] > 0 ^ vjit[2] > 0) {
115	greg	2.7	double dx = vsrc[0] + vjit[0];
116			double dy = vsrc[1] + vjit[1];
117	greg	2.9	if (dxdx + dydy <= ndp->thru_psa)
118	greg	2.7	return(0);
119			}
120			ec = SDevalBSDF(&sv, vjit, vsrc, ndp->sd);
121			if (ec)
122			objerror(ndp->mp, USER, transSDError(ec));
123
124			if (sv.cieY <= FTINY) /* not worth using? */
125			return(0);
126			/* else we're good to go */
127			cvt_sdcolor(cval, &sv);
128			return(1);
129			}
130
131	greg	2.5	/* Compute source contribution for BSDF (reflected & transmitted) */
132	greg	2.1	static void
133	greg	2.5	dir_bsdf(
134	greg	2.1	COLOR cval, /* returned coefficient */
135			void nnp, / material data */
136			FVECT ldir, /* light source direction */
137			double omega /* light source size */
138			)
139			{
140	greg	2.3	BSDFDAT np = (BSDFDAT )nnp;
141	greg	2.1	double ldot;
142			double dtmp;
143			COLOR ctmp;
144
145			setcolor(cval, .0, .0, .0);
146
147			ldot = DOT(np->pnorm, ldir);
148			if ((-FTINY <= ldot) & (ldot <= FTINY))
149			return;
150
151	greg	2.9	if (ldot > 0 && bright(np->rdiff) > FTINY) {
152	greg	2.1	/*
153			* Compute added diffuse reflected component.
154			*/
155			copycolor(ctmp, np->rdiff);
156			dtmp = ldot * omega * (1./PI);
157			scalecolor(ctmp, dtmp);
158			addcolor(cval, ctmp);
159			}
160	greg	2.9	if (ldot < 0 && bright(np->tdiff) > FTINY) {
161	greg	2.1	/*
162			* Compute added diffuse transmission.
163			*/
164			copycolor(ctmp, np->tdiff);
165			dtmp = -ldot * omega * (1.0/PI);
166			scalecolor(ctmp, dtmp);
167			addcolor(cval, ctmp);
168			}
169			/*
170			* Compute scattering coefficient using BSDF.
171			*/
172	greg	2.7	if (!direct_bsdf_OK(ctmp, ldir, np))
173	greg	2.1	return;
174	greg	2.9	if (ldot > 0) { /* pattern only diffuse reflection */
175	greg	2.1	COLOR ctmp1, ctmp2;
176	greg	2.9	dtmp = (np->pr->rod > 0) ? np->sd->rLambFront.cieY
177	greg	2.1	: np->sd->rLambBack.cieY;
178	greg	2.7	/* diffuse fraction */
179			dtmp /= PI * bright(ctmp);
180	greg	2.1	copycolor(ctmp2, np->pr->pcol);
181			scalecolor(ctmp2, dtmp);
182			setcolor(ctmp1, 1.-dtmp, 1.-dtmp, 1.-dtmp);
183			addcolor(ctmp1, ctmp2);
184	greg	2.3	multcolor(ctmp, ctmp1); /* apply derated pattern */
185	greg	2.1	dtmp = ldot * omega;
186			} else { /* full pattern on transmission */
187			multcolor(ctmp, np->pr->pcol);
188			dtmp = -ldot * omega;
189			}
190			scalecolor(ctmp, dtmp);
191			addcolor(cval, ctmp);
192			}
193
194	greg	2.5	/* Compute source contribution for BSDF (reflected only) */
195			static void
196			dir_brdf(
197			COLOR cval, /* returned coefficient */
198			void nnp, / material data */
199			FVECT ldir, /* light source direction */
200			double omega /* light source size */
201			)
202			{
203			BSDFDAT np = (BSDFDAT )nnp;
204			double ldot;
205			double dtmp;
206			COLOR ctmp, ctmp1, ctmp2;
207
208			setcolor(cval, .0, .0, .0);
209
210			ldot = DOT(np->pnorm, ldir);
211
212			if (ldot <= FTINY)
213			return;
214
215			if (bright(np->rdiff) > FTINY) {
216			/*
217			* Compute added diffuse reflected component.
218			*/
219			copycolor(ctmp, np->rdiff);
220			dtmp = ldot * omega * (1./PI);
221			scalecolor(ctmp, dtmp);
222			addcolor(cval, ctmp);
223			}
224			/*
225			* Compute reflection coefficient using BSDF.
226			*/
227	greg	2.7	if (!direct_bsdf_OK(ctmp, ldir, np))
228	greg	2.5	return;
229			/* pattern only diffuse reflection */
230	greg	2.9	dtmp = (np->pr->rod > 0) ? np->sd->rLambFront.cieY
231	greg	2.5	: np->sd->rLambBack.cieY;
232	greg	2.7	dtmp /= PI * bright(ctmp); /* diffuse fraction */
233	greg	2.5	copycolor(ctmp2, np->pr->pcol);
234			scalecolor(ctmp2, dtmp);
235			setcolor(ctmp1, 1.-dtmp, 1.-dtmp, 1.-dtmp);
236			addcolor(ctmp1, ctmp2);
237			multcolor(ctmp, ctmp1); /* apply derated pattern */
238			dtmp = ldot * omega;
239			scalecolor(ctmp, dtmp);
240			addcolor(cval, ctmp);
241			}
242
243			/* Compute source contribution for BSDF (transmitted only) */
244			static void
245			dir_btdf(
246			COLOR cval, /* returned coefficient */
247			void nnp, / material data */
248			FVECT ldir, /* light source direction */
249			double omega /* light source size */
250			)
251			{
252			BSDFDAT np = (BSDFDAT )nnp;
253			double ldot;
254			double dtmp;
255			COLOR ctmp;
256
257			setcolor(cval, .0, .0, .0);
258
259			ldot = DOT(np->pnorm, ldir);
260
261			if (ldot >= -FTINY)
262			return;
263
264			if (bright(np->tdiff) > FTINY) {
265			/*
266			* Compute added diffuse transmission.
267			*/
268			copycolor(ctmp, np->tdiff);
269			dtmp = -ldot * omega * (1.0/PI);
270			scalecolor(ctmp, dtmp);
271			addcolor(cval, ctmp);
272			}
273			/*
274			* Compute scattering coefficient using BSDF.
275			*/
276	greg	2.7	if (!direct_bsdf_OK(ctmp, ldir, np))
277	greg	2.5	return;
278			/* full pattern on transmission */
279			multcolor(ctmp, np->pr->pcol);
280			dtmp = -ldot * omega;
281			scalecolor(ctmp, dtmp);
282			addcolor(cval, ctmp);
283			}
284
285	greg	2.1	/* Sample separate BSDF component */
286			static int
287			sample_sdcomp(BSDFDAT ndp, SDComponent dcp, int usepat)
288			{
289			int nstarget = 1;
290			int nsent = 0;
291			SDError ec;
292			SDValue bsv;
293			double sthick;
294	greg	2.10	FVECT vsmp;
295	greg	2.1	RAY sr;
296			int ntrials;
297			/* multiple samples? */
298			if (specjitter > 1.5) {
299			nstarget = specjitter*ndp->pr->rweight + .5;
300			if (nstarget < 1)
301			nstarget = 1;
302			}
303			/* run through our trials */
304			for (ntrials = 0; nsent < nstarget && ntrials < 9*nstarget; ntrials++) {
305			SDerrorDetail[0] = '\0';
306			/* sample direction & coef. */
307	greg	2.10	bsdf_jitter(vsmp, ndp, 0);
308			ec = SDsampComponent(&bsv, vsmp, ntrials ? frandom()
309	greg	2.4	: urand(ilhash(dimlist,ndims)+samplendx), dcp);
310	greg	2.1	if (ec)
311	greg	2.2	objerror(ndp->mp, USER, transSDError(ec));
312	greg	2.1	/* zero component? */
313			if (bsv.cieY <= FTINY)
314			break;
315			/* map vector to world */
316	greg	2.4	if (SDmapDir(sr.rdir, ndp->fromloc, vsmp) != SDEnone)
317	greg	2.1	break;
318			/* unintentional penetration? */
319	greg	2.9	if (DOT(sr.rdir, ndp->pr->ron) > 0 ^ vsmp[2] > 0)
320	greg	2.1	continue;
321			/* spawn a specular ray */
322			if (nstarget > 1)
323			bsv.cieY /= (double)nstarget;
324			cvt_sdcolor(sr.rcoef, &bsv); /* use color */
325			if (usepat) /* pattern on transmission */
326			multcolor(sr.rcoef, ndp->pr->pcol);
327			if (rayorigin(&sr, SPECULAR, ndp->pr, sr.rcoef) < 0) {
328			if (maxdepth > 0)
329			break;
330			++nsent; /* Russian roulette victim */
331			continue;
332			}
333	greg	2.5	/* need to offset origin? */
334	greg	2.9	if (ndp->thick != 0 && ndp->pr->rod > 0 ^ vsmp[2] > 0)
335	greg	2.5	VSUM(sr.rorg, sr.rorg, ndp->pr->ron, -ndp->thick);
336	greg	2.1	rayvalue(&sr); /* send & evaluate sample */
337			multcolor(sr.rcol, sr.rcoef);
338			addcolor(ndp->pr->rcol, sr.rcol);
339			++nsent;
340			}
341			return(nsent);
342			}
343
344			/* Sample non-diffuse components of BSDF */
345			static int
346			sample_sdf(BSDFDAT *ndp, int sflags)
347			{
348			int n, ntotal = 0;
349			SDSpectralDF *dfp;
350			COLORV *unsc;
351
352			if (sflags == SDsampSpT) {
353			unsc = ndp->tunsamp;
354			dfp = ndp->sd->tf;
355			cvt_sdcolor(unsc, &ndp->sd->tLamb);
356			} else /* sflags == SDsampSpR */ {
357			unsc = ndp->runsamp;
358	greg	2.9	if (ndp->pr->rod > 0) {
359	greg	2.1	dfp = ndp->sd->rf;
360			cvt_sdcolor(unsc, &ndp->sd->rLambFront);
361			} else {
362			dfp = ndp->sd->rb;
363			cvt_sdcolor(unsc, &ndp->sd->rLambBack);
364			}
365			}
366			multcolor(unsc, ndp->pr->pcol);
367			if (dfp == NULL) /* no specular component? */
368			return(0);
369			/* below sampling threshold? */
370			if (dfp->maxHemi <= specthresh+FTINY) {
371	greg	2.3	if (dfp->maxHemi > FTINY) { /* XXX no color from BSDF */
372	greg	2.4	FVECT vjit;
373			double d;
374	greg	2.1	COLOR ctmp;
375	greg	2.9	bsdf_jitter(vjit, ndp, 1);
376	greg	2.4	d = SDdirectHemi(vjit, sflags, ndp->sd);
377	greg	2.1	if (sflags == SDsampSpT) {
378			copycolor(ctmp, ndp->pr->pcol);
379			scalecolor(ctmp, d);
380			} else /* no pattern on reflection */
381			setcolor(ctmp, d, d, d);
382			addcolor(unsc, ctmp);
383			}
384			return(0);
385			}
386			/* else need to sample */
387			dimlist[ndims++] = (int)(size_t)ndp->mp;
388			ndims++;
389			for (n = dfp->ncomp; n--; ) { /* loop over components */
390			dimlist[ndims-1] = n + 9438;
391			ntotal += sample_sdcomp(ndp, &dfp->comp[n], sflags==SDsampSpT);
392			}
393			ndims -= 2;
394			return(ntotal);
395			}
396
397			/* Color a ray that hit a BSDF material */
398			int
399			m_bsdf(OBJREC m, RAY r)
400			{
401	greg	2.6	int hitfront;
402	greg	2.1	COLOR ctmp;
403			SDError ec;
404	greg	2.5	FVECT upvec, vtmp;
405	greg	2.1	MFUNC *mf;
406			BSDFDAT nd;
407			/* check arguments */
408			if ((m->oargs.nsargs < 6) \| (m->oargs.nfargs > 9) \|
409			(m->oargs.nfargs % 3))
410			objerror(m, USER, "bad # arguments");
411	greg	2.6	/* record surface struck */
412	greg	2.9	hitfront = (r->rod > 0);
413	greg	2.1	/* load cal file */
414			mf = getfunc(m, 5, 0x1d, 1);
415			/* get thickness */
416			nd.thick = evalue(mf->ep[0]);
417	greg	2.5	if ((-FTINY <= nd.thick) & (nd.thick <= FTINY))
418	greg	2.1	nd.thick = .0;
419			/* check shadow */
420			if (r->crtype & SHADOW) {
421	greg	2.9	if (nd.thick != 0)
422	greg	2.3	raytrans(r); /* pass-through */
423	greg	2.5	return(1); /* or shadow */
424	greg	2.1	}
425	greg	2.5	/* check other rays to pass */
426	greg	2.9	if (nd.thick != 0 && (!(r->crtype & (SPECULAR\|AMBIENT)) \|\|
427			nd.thick > 0 ^ hitfront)) {
428	greg	2.5	raytrans(r); /* hide our proxy */
429	greg	2.1	return(1);
430			}
431	greg	2.5	/* get BSDF data */
432			nd.sd = loadBSDF(m->oargs.sarg[1]);
433	greg	2.1	/* diffuse reflectance */
434	greg	2.6	if (hitfront) {
435	greg	2.1	if (m->oargs.nfargs < 3)
436			setcolor(nd.rdiff, .0, .0, .0);
437			else
438			setcolor(nd.rdiff, m->oargs.farg[0],
439			m->oargs.farg[1],
440			m->oargs.farg[2]);
441			} else {
442			if (m->oargs.nfargs < 6) { /* check invisible backside */
443	greg	2.3	if (!backvis && (nd.sd->rb == NULL) &
444			(nd.sd->tf == NULL)) {
445	greg	2.1	SDfreeCache(nd.sd);
446			raytrans(r);
447			return(1);
448			}
449			setcolor(nd.rdiff, .0, .0, .0);
450			} else
451			setcolor(nd.rdiff, m->oargs.farg[3],
452			m->oargs.farg[4],
453			m->oargs.farg[5]);
454			}
455			/* diffuse transmittance */
456			if (m->oargs.nfargs < 9)
457			setcolor(nd.tdiff, .0, .0, .0);
458			else
459			setcolor(nd.tdiff, m->oargs.farg[6],
460			m->oargs.farg[7],
461			m->oargs.farg[8]);
462			nd.mp = m;
463			nd.pr = r;
464			/* get modifiers */
465			raytexture(r, m->omod);
466			/* modify diffuse values */
467			multcolor(nd.rdiff, r->pcol);
468			multcolor(nd.tdiff, r->pcol);
469			/* get up vector */
470			upvec[0] = evalue(mf->ep[1]);
471			upvec[1] = evalue(mf->ep[2]);
472			upvec[2] = evalue(mf->ep[3]);
473			/* return to world coords */
474			if (mf->f != &unitxf) {
475			multv3(upvec, upvec, mf->f->xfm);
476			nd.thick *= mf->f->sca;
477			}
478			raynormal(nd.pnorm, r);
479			/* compute local BSDF xform */
480			ec = SDcompXform(nd.toloc, nd.pnorm, upvec);
481			if (!ec) {
482	greg	2.4	nd.vray[0] = -r->rdir[0];
483			nd.vray[1] = -r->rdir[1];
484			nd.vray[2] = -r->rdir[2];
485			ec = SDmapDir(nd.vray, nd.toloc, nd.vray);
486	greg	2.1	}
487			if (!ec)
488			ec = SDinvXform(nd.fromloc, nd.toloc);
489	greg	2.4	/* determine BSDF resolution */
490			if (!ec)
491	greg	2.9	ec = SDsizeBSDF(nd.sr_vpsa, nd.vray, NULL,
492			SDqueryMin+SDqueryMax, nd.sd);
493			nd.thru_psa = .0;
494			if (!ec && nd.thick != 0 && r->crtype & (SPECULAR\|AMBIENT)) {
495			FVECT vthru;
496			vthru[0] = -nd.vray[0];
497			vthru[1] = -nd.vray[1];
498			vthru[2] = -nd.vray[2];
499			ec = SDsizeBSDF(&nd.thru_psa, nd.vray, vthru,
500			SDqueryMin, nd.sd);
501			}
502			if (ec) {
503	greg	2.2	objerror(m, WARNING, transSDError(ec));
504	greg	2.1	SDfreeCache(nd.sd);
505			return(1);
506			}
507	greg	2.9	nd.sr_vpsa[0] = sqrt(nd.sr_vpsa[0]);
508			nd.sr_vpsa[1] = sqrt(nd.sr_vpsa[1]);
509	greg	2.6	if (!hitfront) { /* perturb normal towards hit */
510	greg	2.1	nd.pnorm[0] = -nd.pnorm[0];
511			nd.pnorm[1] = -nd.pnorm[1];
512			nd.pnorm[2] = -nd.pnorm[2];
513			}
514			/* sample reflection */
515			sample_sdf(&nd, SDsampSpR);
516			/* sample transmission */
517			sample_sdf(&nd, SDsampSpT);
518			/* compute indirect diffuse */
519			copycolor(ctmp, nd.rdiff);
520			addcolor(ctmp, nd.runsamp);
521	greg	2.5	if (bright(ctmp) > FTINY) { /* ambient from reflection */
522	greg	2.6	if (!hitfront)
523	greg	2.1	flipsurface(r);
524			multambient(ctmp, r, nd.pnorm);
525			addcolor(r->rcol, ctmp);
526	greg	2.6	if (!hitfront)
527	greg	2.1	flipsurface(r);
528			}
529			copycolor(ctmp, nd.tdiff);
530			addcolor(ctmp, nd.tunsamp);
531			if (bright(ctmp) > FTINY) { /* ambient from other side */
532			FVECT bnorm;
533	greg	2.6	if (hitfront)
534	greg	2.1	flipsurface(r);
535			bnorm[0] = -nd.pnorm[0];
536			bnorm[1] = -nd.pnorm[1];
537			bnorm[2] = -nd.pnorm[2];
538	greg	2.9	if (nd.thick != 0) { /* proxy with offset? */
539	greg	2.5	VCOPY(vtmp, r->rop);
540			VSUM(r->rop, vtmp, r->ron, -nd.thick);
541			multambient(ctmp, r, bnorm);
542			VCOPY(r->rop, vtmp);
543			} else
544			multambient(ctmp, r, bnorm);
545	greg	2.1	addcolor(r->rcol, ctmp);
546	greg	2.6	if (hitfront)
547	greg	2.1	flipsurface(r);
548			}
549			/* add direct component */
550	greg	2.5	if ((bright(nd.tdiff) <= FTINY) & (nd.sd->tf == NULL)) {
551			direct(r, dir_brdf, &nd); /* reflection only */
552	greg	2.9	} else if (nd.thick == 0) {
553	greg	2.5	direct(r, dir_bsdf, &nd); /* thin surface scattering */
554			} else {
555			direct(r, dir_brdf, &nd); /* reflection first */
556			VCOPY(vtmp, r->rop); /* offset for transmitted */
557			VSUM(r->rop, vtmp, r->ron, -nd.thick);
558	greg	2.6	direct(r, dir_btdf, &nd); /* separate transmission */
559	greg	2.5	VCOPY(r->rop, vtmp);
560			}
561	greg	2.1	/* clean up */
562			SDfreeCache(nd.sd);
563			return(1);
564			}