src/rt/aniso.c

#ifndef lint
static const char RCSid[] = "$Id: aniso.c,v 2.56 2014/01/25 18:27:39 greg Exp $";
#endif
/*
 *  Shading functions for anisotropic materials.
 */

#include "copyright.h"

#include  "ray.h"
#include  "ambient.h"
#include  "otypes.h"
#include  "rtotypes.h"
#include  "source.h"
#include  "func.h"
#include  "random.h"

#ifndef  MAXITER
#define  MAXITER        10              /* maximum # specular ray attempts */
#endif

/*
 *      This routine implements the anisotropic Gaussian
 *  model described by Ward in Siggraph `92 article, updated with
 *  normalization and sampling adjustments due to Geisler-Moroder and Duer.
 *      We orient the surface towards the incoming ray, so a single
 *  surface can be used to represent an infinitely thin object.
 *
 *  Arguments for MAT_PLASTIC2 and MAT_METAL2 are:
 *  4+ ux       uy      uz      funcfile        [transform...]
 *  0
 *  6  red      grn     blu     specular-frac.  u-rough v-rough
 *
 *  Real arguments for MAT_TRANS2 are:
 *  8  red      grn     blu     rspec   u-rough v-rough trans   tspec
 */

                                /* specularity flags */
#define  SP_REFL        01              /* has reflected specular component */
#define  SP_TRAN        02              /* has transmitted specular */
#define  SP_FLAT        04              /* reflecting surface is flat */
#define  SP_RBLT        010             /* reflection below sample threshold */
#define  SP_TBLT        020             /* transmission below threshold */

typedef struct {
        OBJREC  *mp;            /* material pointer */
        RAY  *rp;               /* ray pointer */
        short  specfl;          /* specularity flags, defined above */
        COLOR  mcolor;          /* color of this material */
        COLOR  scolor;          /* color of specular component */
        FVECT  vrefl;           /* vector in reflected direction */
        FVECT  prdir;           /* vector in transmitted direction */
        FVECT  u, v;            /* u and v vectors orienting anisotropy */
        double  u_alpha;        /* u roughness */
        double  v_alpha;        /* v roughness */
        double  rdiff, rspec;   /* reflected specular, diffuse */
        double  trans;          /* transmissivity */
        double  tdiff, tspec;   /* transmitted specular, diffuse */
        FVECT  pnorm;           /* perturbed surface normal */
        double  pdot;           /* perturbed dot product */
}  ANISODAT;            /* anisotropic material data */

static void getacoords(ANISODAT  *np);
static void agaussamp(ANISODAT  *np);


static void
diraniso(               /* compute source contribution */
        COLOR  cval,                    /* returned coefficient */
        void  *nnp,                     /* material data */
        FVECT  ldir,                    /* light source direction */
        double  omega                   /* light source size */
)
{
        ANISODAT *np = nnp;
        double  ldot;
        double  dtmp, dtmp1, dtmp2;
        FVECT  h;
        double  au2, av2;
        COLOR  ctmp;

        setcolor(cval, 0.0, 0.0, 0.0);

        ldot = DOT(np->pnorm, ldir);

        if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY)
                return;         /* wrong side */

        if ((ldot > FTINY) & (np->rdiff > FTINY)) {
                /*
                 *  Compute and add diffuse reflected component to returned
                 *  color.  The diffuse reflected component will always be
                 *  modified by the color of the material.
                 */
                copycolor(ctmp, np->mcolor);
                dtmp = ldot * omega * np->rdiff * (1.0/PI);
                scalecolor(ctmp, dtmp);
                addcolor(cval, ctmp);
        }
        if (ldot > FTINY && np->specfl&SP_REFL) {
                /*
                 *  Compute specular reflection coefficient using
                 *  anisotropic Gaussian distribution model.
                 */
                                                /* add source width if flat */
                if (np->specfl & SP_FLAT)
                        au2 = av2 = omega * (0.25/PI);
                else
                        au2 = av2 = 0.0;
                au2 += np->u_alpha*np->u_alpha;
                av2 += np->v_alpha*np->v_alpha;
                                                /* half vector */
                VSUB(h, ldir, np->rp->rdir);
                                                /* ellipse */
                dtmp1 = DOT(np->u, h);
                dtmp1 *= dtmp1 / au2;
                dtmp2 = DOT(np->v, h);
                dtmp2 *= dtmp2 / av2;
                                                /* new W-G-M-D model */
                dtmp = DOT(np->pnorm, h);
                dtmp *= dtmp;
                dtmp1 = (dtmp1 + dtmp2) / dtmp;
                dtmp = exp(-dtmp1) * DOT(h,h) /
                                (PI * dtmp*dtmp * sqrt(au2*av2));
                                                /* worth using? */
                if (dtmp > FTINY) {
                        copycolor(ctmp, np->scolor);
                        dtmp *= ldot * omega;
                        scalecolor(ctmp, dtmp);
                        addcolor(cval, ctmp);
                }
        }
        if ((ldot < -FTINY) & (np->tdiff > FTINY)) {
                /*
                 *  Compute diffuse transmission.
                 */
                copycolor(ctmp, np->mcolor);
                dtmp = -ldot * omega * np->tdiff * (1.0/PI);
                scalecolor(ctmp, dtmp);
                addcolor(cval, ctmp);
        }
        if (ldot < -FTINY && np->specfl&SP_TRAN) {
                /*
                 *  Compute specular transmission.  Specular transmission
                 *  is always modified by material color.
                 */
                                                /* roughness + source */
                au2 = av2 = omega * (1.0/PI);
                au2 += np->u_alpha*np->u_alpha;
                av2 += np->v_alpha*np->v_alpha;
                                                /* "half vector" */
                VSUB(h, ldir, np->prdir);
                dtmp = DOT(h,h);
                if (dtmp > FTINY*FTINY) {
                        dtmp1 = DOT(h,np->pnorm);
                        dtmp = 1.0 - dtmp1*dtmp1/dtmp;
                        if (dtmp > FTINY*FTINY) {
                                dtmp1 = DOT(h,np->u);
                                dtmp1 *= dtmp1 / au2;
                                dtmp2 = DOT(h,np->v);
                                dtmp2 *= dtmp2 / av2;
                                dtmp = (dtmp1 + dtmp2) / dtmp;
                        }
                } else
                        dtmp = 0.0;
                                                /* Gaussian */
                dtmp = exp(-dtmp) * (1.0/PI) * sqrt(-ldot/(np->pdot*au2*av2));
                                                /* worth using? */
                if (dtmp > FTINY) {
                        copycolor(ctmp, np->mcolor);
                        dtmp *= np->tspec * omega;
                        scalecolor(ctmp, dtmp);
                        addcolor(cval, ctmp);
                }
        }
}


int
m_aniso(                        /* shade ray that hit something anisotropic */
        OBJREC  *m,
        RAY  *r
)
{
        ANISODAT  nd;
        COLOR  ctmp;
        int  i;
                                                /* easy shadow test */
        if (r->crtype & SHADOW)
                return(1);

        if (m->oargs.nfargs != (m->otype == MAT_TRANS2 ? 8 : 6))
                objerror(m, USER, "bad number of real arguments");
                                                /* check for back side */
        if (r->rod < 0.0) {
                if (!backvis) {
                        raytrans(r);
                        return(1);
                }
                raytexture(r, m->omod);
                flipsurface(r);                 /* reorient if backvis */
        } else
                raytexture(r, m->omod);
                                                /* get material color */
        nd.mp = m;
        nd.rp = r;
        setcolor(nd.mcolor, m->oargs.farg[0],
                           m->oargs.farg[1],
                           m->oargs.farg[2]);
                                                /* get roughness */
        nd.specfl = 0;
        nd.u_alpha = m->oargs.farg[4];
        nd.v_alpha = m->oargs.farg[5];
        if ((nd.u_alpha <= FTINY) | (nd.v_alpha <= FTINY))
                objerror(m, USER, "roughness too small");

        nd.pdot = raynormal(nd.pnorm, r);       /* perturb normal */
        if (nd.pdot < .001)
                nd.pdot = .001;                 /* non-zero for diraniso() */
        multcolor(nd.mcolor, r->pcol);          /* modify material color */
                                                /* get specular component */
        if ((nd.rspec = m->oargs.farg[3]) > FTINY) {
                nd.specfl |= SP_REFL;
                                                /* compute specular color */
                if (m->otype == MAT_METAL2)
                        copycolor(nd.scolor, nd.mcolor);
                else
                        setcolor(nd.scolor, 1.0, 1.0, 1.0);
                scalecolor(nd.scolor, nd.rspec);
                                                /* check threshold */
                if (specthresh >= nd.rspec-FTINY)
                        nd.specfl |= SP_RBLT;
                                                /* compute refl. direction */
                VSUM(nd.vrefl, r->rdir, nd.pnorm, 2.0*nd.pdot);
                if (DOT(nd.vrefl, r->ron) <= FTINY)     /* penetration? */
                        VSUM(nd.vrefl, r->rdir, r->ron, 2.0*r->rod);
        }
                                                /* compute transmission */
        if (m->otype == MAT_TRANS2) {
                nd.trans = m->oargs.farg[6]*(1.0 - nd.rspec);
                nd.tspec = nd.trans * m->oargs.farg[7];
                nd.tdiff = nd.trans - nd.tspec;
                if (nd.tspec > FTINY) {
                        nd.specfl |= SP_TRAN;
                                                        /* check threshold */
                        if (specthresh >= nd.tspec-FTINY)
                                nd.specfl |= SP_TBLT;
                        if (DOT(r->pert,r->pert) <= FTINY*FTINY) {
                                VCOPY(nd.prdir, r->rdir);
                        } else {
                                for (i = 0; i < 3; i++)         /* perturb */
                                        nd.prdir[i] = r->rdir[i] - r->pert[i];
                                if (DOT(nd.prdir, r->ron) < -FTINY)
                                        normalize(nd.prdir);    /* OK */
                                else
                                        VCOPY(nd.prdir, r->rdir);
                        }
                }
        } else
                nd.tdiff = nd.tspec = nd.trans = 0.0;

                                                /* diffuse reflection */
        nd.rdiff = 1.0 - nd.trans - nd.rspec;

        if (r->ro != NULL && isflat(r->ro->otype))
                nd.specfl |= SP_FLAT;

        getacoords(&nd);                        /* set up coordinates */

        if (nd.specfl & (SP_REFL|SP_TRAN))
                agaussamp(&nd);

        if (nd.rdiff > FTINY) {         /* ambient from this side */
                copycolor(ctmp, nd.mcolor);     /* modified by material color */
                scalecolor(ctmp, nd.rdiff);
                if (nd.specfl & SP_RBLT)        /* add in specular as well? */
                        addcolor(ctmp, nd.scolor);
                multambient(ctmp, r, nd.pnorm);
                addcolor(r->rcol, ctmp);        /* add to returned color */
        }
        if (nd.tdiff > FTINY) {         /* ambient from other side */
                FVECT  bnorm;

                flipsurface(r);
                bnorm[0] = -nd.pnorm[0];
                bnorm[1] = -nd.pnorm[1];
                bnorm[2] = -nd.pnorm[2];
                copycolor(ctmp, nd.mcolor);     /* modified by color */
                if (nd.specfl & SP_TBLT)
                        scalecolor(ctmp, nd.trans);
                else
                        scalecolor(ctmp, nd.tdiff);
                multambient(ctmp, r, bnorm);
                addcolor(r->rcol, ctmp);
                flipsurface(r);
        }
                                        /* add direct component */
        direct(r, diraniso, &nd);

        return(1);
}


static void
getacoords(             /* set up coordinate system */
        ANISODAT  *np
)
{
        MFUNC  *mf;
        int  i;

        mf = getfunc(np->mp, 3, 0x7, 1);
        setfunc(np->mp, np->rp);
        errno = 0;
        for (i = 0; i < 3; i++)
                np->u[i] = evalue(mf->ep[i]);
        if ((errno == EDOM) | (errno == ERANGE))
                np->u[0] = np->u[1] = np->u[2] = 0.0;
        if (mf->fxp != &unitxf)
                multv3(np->u, np->u, mf->fxp->xfm);
        fcross(np->v, np->pnorm, np->u);
        if (normalize(np->v) == 0.0) {
                if (fabs(np->u_alpha - np->v_alpha) > 0.001)
                        objerror(np->mp, WARNING, "illegal orientation vector");
                getperpendicular(np->u, np->pnorm);     /* punting */
                fcross(np->v, np->pnorm, np->u);
                np->u_alpha = np->v_alpha = sqrt( 0.5 *
                        (np->u_alpha*np->u_alpha + np->v_alpha*np->v_alpha) );
        } else
                fcross(np->u, np->v, np->pnorm);
}


static void
agaussamp(              /* sample anisotropic Gaussian specular */
        ANISODAT  *np
)
{
        RAY  sr;
        FVECT  h;
        double  rv[2];
        double  d, sinp, cosp;
        COLOR   scol;
        int  maxiter, ntrials, nstarget, nstaken;
        int  i;
                                        /* compute reflection */
        if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL &&
                        rayorigin(&sr, SPECULAR, np->rp, np->scolor) == 0) {
                nstarget = 1;
                if (specjitter > 1.5) { /* multiple samples? */
                        nstarget = specjitter*np->rp->rweight + .5;
                        if (sr.rweight <= minweight*nstarget)
                                nstarget = sr.rweight/minweight;
                        if (nstarget > 1) {
                                d = 1./nstarget;
                                scalecolor(sr.rcoef, d);
                                sr.rweight *= d;
                        } else
                                nstarget = 1;
                }
                setcolor(scol, 0., 0., 0.);
                dimlist[ndims++] = (int)(size_t)np->mp;
                maxiter = MAXITER*nstarget;
                for (nstaken = ntrials = 0; nstaken < nstarget &&
                                                ntrials < maxiter; ntrials++) {
                        if (ntrials)
                                d = frandom();
                        else
                                d = urand(ilhash(dimlist,ndims)+samplendx);
                        multisamp(rv, 2, d);
                        d = 2.0*PI * rv[0];
                        cosp = tcos(d) * np->u_alpha;
                        sinp = tsin(d) * np->v_alpha;
                        d = 1./sqrt(cosp*cosp + sinp*sinp);
                        cosp *= d;
                        sinp *= d;
                        if ((0. <= specjitter) & (specjitter < 1.))
                                rv[1] = 1.0 - specjitter*rv[1];
                        if (rv[1] <= FTINY)
                                d = 1.0;
                        else
                                d = sqrt(-log(rv[1]) /
                                        (cosp*cosp/(np->u_alpha*np->u_alpha) +
                                         sinp*sinp/(np->v_alpha*np->v_alpha)));
                        for (i = 0; i < 3; i++)
                                h[i] = np->pnorm[i] +
                                        d*(cosp*np->u[i] + sinp*np->v[i]);
                        d = -2.0 * DOT(h, np->rp->rdir) / (1.0 + d*d);
                        VSUM(sr.rdir, np->rp->rdir, h, d);
                                                /* sample rejection test */
                        if ((d = DOT(sr.rdir, np->rp->ron)) <= FTINY)
                                continue;
                        checknorm(sr.rdir);
                        if (nstarget > 1) {     /* W-G-M-D adjustment */
                                if (nstaken) rayclear(&sr);
                                rayvalue(&sr);
                                d = 2./(1. + np->rp->rod/d);
                                scalecolor(sr.rcol, d);
                                addcolor(scol, sr.rcol);
                        } else {
                                rayvalue(&sr);
                                multcolor(sr.rcol, sr.rcoef);
                                addcolor(np->rp->rcol, sr.rcol);
                        }
                        ++nstaken;
                }
                if (nstarget > 1) {             /* final W-G-M-D weighting */
                        multcolor(scol, sr.rcoef);
                        d = (double)nstarget/ntrials;
                        scalecolor(scol, d);
                        addcolor(np->rp->rcol, scol);
                }
                ndims--;
        }
                                        /* compute transmission */
        copycolor(sr.rcoef, np->mcolor);                /* modify by material color */
        scalecolor(sr.rcoef, np->tspec);
        if ((np->specfl & (SP_TRAN|SP_TBLT)) == SP_TRAN &&
                        rayorigin(&sr, SPECULAR, np->rp, sr.rcoef) == 0) {
                nstarget = 1;
                if (specjitter > 1.5) { /* multiple samples? */
                        nstarget = specjitter*np->rp->rweight + .5;
                        if (sr.rweight <= minweight*nstarget)
                                nstarget = sr.rweight/minweight;
                        if (nstarget > 1) {
                                d = 1./nstarget;
                                scalecolor(sr.rcoef, d);
                                sr.rweight *= d;
                        } else
                                nstarget = 1;
                }
                dimlist[ndims++] = (int)(size_t)np->mp;
                maxiter = MAXITER*nstarget;
                for (nstaken = ntrials = 0; nstaken < nstarget &&
                                                ntrials < maxiter; ntrials++) {
                        if (ntrials)
                                d = frandom();
                        else
                                d = urand(ilhash(dimlist,ndims)+1823+samplendx);
                        multisamp(rv, 2, d);
                        d = 2.0*PI * rv[0];
                        cosp = tcos(d) * np->u_alpha;
                        sinp = tsin(d) * np->v_alpha;
                        d = 1./sqrt(cosp*cosp + sinp*sinp);
                        cosp *= d;
                        sinp *= d;
                        if ((0. <= specjitter) & (specjitter < 1.))
                                rv[1] = 1.0 - specjitter*rv[1];
                        if (rv[1] <= FTINY)
                                d = 1.0;
                        else
                                d = sqrt(-log(rv[1]) /
                                        (cosp*cosp/(np->u_alpha*np->u_alpha) +
                                         sinp*sinp/(np->v_alpha*np->v_alpha)));
                        for (i = 0; i < 3; i++)
                                sr.rdir[i] = np->prdir[i] +
                                                d*(cosp*np->u[i] + sinp*np->v[i]);
                        if (DOT(sr.rdir, np->rp->ron) >= -FTINY)
                                continue;
                        normalize(sr.rdir);     /* OK, normalize */
                        if (nstaken)            /* multi-sampling */
                                rayclear(&sr);
                        rayvalue(&sr);
                        multcolor(sr.rcol, sr.rcoef);
                        addcolor(np->rp->rcol, sr.rcol);
                        ++nstaken;
                }
                ndims--;
        }
}
Revision:	2.57
Committed:	Thu Dec 4 05:26:28 2014 UTC (9 years, 5 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.56:	+14 -15 lines
Log Message:	Improved behavior of anisotropic reflections
#	User	Rev	Content
1	greg	2.1	#ifndef lint
2	greg	2.57	static const char RCSid[] = "$Id: aniso.c,v 2.56 2014/01/25 18:27:39 greg Exp $";
3	greg	2.1	#endif
4			/*
5			* Shading functions for anisotropic materials.
6			*/
7
8	greg	2.35	#include "copyright.h"
9	greg	2.34
10	greg	2.1	#include "ray.h"
11	greg	2.40	#include "ambient.h"
12	greg	2.1	#include "otypes.h"
13	schorsch	2.41	#include "rtotypes.h"
14			#include "source.h"
15	greg	2.1	#include "func.h"
16			#include "random.h"
17
18	greg	2.32	#ifndef MAXITER
19			#define MAXITER 10 /* maximum # specular ray attempts */
20			#endif
21
22	greg	2.1	/*
23	greg	2.22	* This routine implements the anisotropic Gaussian
24	greg	2.54	* model described by Ward in Siggraph `92 article, updated with
25			* normalization and sampling adjustments due to Geisler-Moroder and Duer.
26	greg	2.1	* We orient the surface towards the incoming ray, so a single
27			* surface can be used to represent an infinitely thin object.
28			*
29			* Arguments for MAT_PLASTIC2 and MAT_METAL2 are:
30			* 4+ ux uy uz funcfile [transform...]
31			* 0
32	greg	2.54	* 6 red grn blu specular-frac. u-rough v-rough
33	greg	2.1	*
34			* Real arguments for MAT_TRANS2 are:
35			* 8 red grn blu rspec u-rough v-rough trans tspec
36			*/
37
38			/* specularity flags */
39			#define SP_REFL 01 /* has reflected specular component */
40			#define SP_TRAN 02 /* has transmitted specular */
41	greg	2.10	#define SP_FLAT 04 /* reflecting surface is flat */
42			#define SP_RBLT 010 /* reflection below sample threshold */
43			#define SP_TBLT 020 /* transmission below threshold */
44	greg	2.1
45			typedef struct {
46	greg	2.2	OBJREC mp; / material pointer */
47	greg	2.1	RAY rp; / ray pointer */
48			short specfl; /* specularity flags, defined above */
49			COLOR mcolor; /* color of this material */
50			COLOR scolor; /* color of specular component */
51	greg	2.6	FVECT vrefl; /* vector in reflected direction */
52	greg	2.1	FVECT prdir; /* vector in transmitted direction */
53			FVECT u, v; /* u and v vectors orienting anisotropy */
54	greg	2.18	double u_alpha; /* u roughness */
55			double v_alpha; /* v roughness */
56	greg	2.1	double rdiff, rspec; /* reflected specular, diffuse */
57			double trans; /* transmissivity */
58			double tdiff, tspec; /* transmitted specular, diffuse */
59			FVECT pnorm; /* perturbed surface normal */
60			double pdot; /* perturbed dot product */
61			} ANISODAT; /* anisotropic material data */
62
63	greg	2.55	static void getacoords(ANISODAT *np);
64			static void agaussamp(ANISODAT *np);
65	greg	2.34
66	greg	2.1
67	greg	2.34	static void
68	schorsch	2.41	diraniso( /* compute source contribution */
69			COLOR cval, /* returned coefficient */
70	greg	2.54	void nnp, / material data */
71	schorsch	2.41	FVECT ldir, /* light source direction */
72			double omega /* light source size */
73			)
74	greg	2.1	{
75	greg	2.54	ANISODAT *np = nnp;
76	greg	2.1	double ldot;
77	greg	2.16	double dtmp, dtmp1, dtmp2;
78	greg	2.1	FVECT h;
79			double au2, av2;
80			COLOR ctmp;
81
82			setcolor(cval, 0.0, 0.0, 0.0);
83
84			ldot = DOT(np->pnorm, ldir);
85
86			if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY)
87			return; /* wrong side */
88
89	greg	2.54	if ((ldot > FTINY) & (np->rdiff > FTINY)) {
90	greg	2.1	/*
91			* Compute and add diffuse reflected component to returned
92			* color. The diffuse reflected component will always be
93			* modified by the color of the material.
94			*/
95			copycolor(ctmp, np->mcolor);
96	greg	2.42	dtmp = ldot * omega * np->rdiff * (1.0/PI);
97	greg	2.1	scalecolor(ctmp, dtmp);
98			addcolor(cval, ctmp);
99			}
100	greg	2.57	if (ldot > FTINY && np->specfl&SP_REFL) {
101	greg	2.1	/*
102			* Compute specular reflection coefficient using
103	greg	2.46	* anisotropic Gaussian distribution model.
104	greg	2.1	*/
105	greg	2.2	/* add source width if flat */
106			if (np->specfl & SP_FLAT)
107	greg	2.42	au2 = av2 = omega * (0.25/PI);
108	greg	2.2	else
109			au2 = av2 = 0.0;
110	greg	2.18	au2 += np->u_alpha*np->u_alpha;
111			av2 += np->v_alpha*np->v_alpha;
112	greg	2.1	/* half vector */
113	greg	2.54	VSUB(h, ldir, np->rp->rdir);
114	greg	2.1	/* ellipse */
115	greg	2.16	dtmp1 = DOT(np->u, h);
116			dtmp1 *= dtmp1 / au2;
117	greg	2.1	dtmp2 = DOT(np->v, h);
118			dtmp2 *= dtmp2 / av2;
119	greg	2.46	/* new W-G-M-D model */
120	greg	2.23	dtmp = DOT(np->pnorm, h);
121	greg	2.46	dtmp *= dtmp;
122			dtmp1 = (dtmp1 + dtmp2) / dtmp;
123			dtmp = exp(-dtmp1) * DOT(h,h) /
124			(PI * dtmpdtmp sqrt(au2*av2));
125	greg	2.1	/* worth using? */
126			if (dtmp > FTINY) {
127			copycolor(ctmp, np->scolor);
128	greg	2.46	dtmp = ldot omega;
129	greg	2.1	scalecolor(ctmp, dtmp);
130			addcolor(cval, ctmp);
131			}
132			}
133	greg	2.54	if ((ldot < -FTINY) & (np->tdiff > FTINY)) {
134	greg	2.1	/*
135			* Compute diffuse transmission.
136			*/
137			copycolor(ctmp, np->mcolor);
138	greg	2.42	dtmp = -ldot * omega * np->tdiff * (1.0/PI);
139	greg	2.1	scalecolor(ctmp, dtmp);
140			addcolor(cval, ctmp);
141			}
142	greg	2.57	if (ldot < -FTINY && np->specfl&SP_TRAN) {
143	greg	2.1	/*
144			* Compute specular transmission. Specular transmission
145			* is always modified by material color.
146			*/
147			/* roughness + source */
148	greg	2.42	au2 = av2 = omega * (1.0/PI);
149	greg	2.18	au2 += np->u_alpha*np->u_alpha;
150			av2 += np->v_alpha*np->v_alpha;
151	greg	2.16	/* "half vector" */
152	greg	2.54	VSUB(h, ldir, np->prdir);
153	greg	2.19	dtmp = DOT(h,h);
154	greg	2.16	if (dtmp > FTINY*FTINY) {
155	greg	2.19	dtmp1 = DOT(h,np->pnorm);
156			dtmp = 1.0 - dtmp1*dtmp1/dtmp;
157			if (dtmp > FTINY*FTINY) {
158			dtmp1 = DOT(h,np->u);
159	greg	2.23	dtmp1 *= dtmp1 / au2;
160	greg	2.19	dtmp2 = DOT(h,np->v);
161	greg	2.23	dtmp2 *= dtmp2 / av2;
162	greg	2.19	dtmp = (dtmp1 + dtmp2) / dtmp;
163			}
164	greg	2.16	} else
165			dtmp = 0.0;
166	greg	2.46	/* Gaussian */
167	greg	2.44	dtmp = exp(-dtmp) * (1.0/PI) * sqrt(-ldot/(np->pdotau2av2));
168	greg	2.1	/* worth using? */
169			if (dtmp > FTINY) {
170			copycolor(ctmp, np->mcolor);
171	greg	2.16	dtmp = np->tspec omega;
172	greg	2.1	scalecolor(ctmp, dtmp);
173			addcolor(cval, ctmp);
174			}
175			}
176			}
177
178
179	greg	2.54	int
180	schorsch	2.41	m_aniso( /* shade ray that hit something anisotropic */
181	greg	2.54	OBJREC *m,
182			RAY *r
183	schorsch	2.41	)
184	greg	2.1	{
185			ANISODAT nd;
186			COLOR ctmp;
187	greg	2.54	int i;
188	greg	2.1	/* easy shadow test */
189	greg	2.10	if (r->crtype & SHADOW)
190	greg	2.27	return(1);
191	greg	2.1
192			if (m->oargs.nfargs != (m->otype == MAT_TRANS2 ? 8 : 6))
193			objerror(m, USER, "bad number of real arguments");
194	greg	2.36	/* check for back side */
195			if (r->rod < 0.0) {
196	greg	2.56	if (!backvis) {
197	greg	2.36	raytrans(r);
198			return(1);
199			}
200			raytexture(r, m->omod);
201			flipsurface(r); /* reorient if backvis */
202			} else
203			raytexture(r, m->omod);
204			/* get material color */
205	greg	2.2	nd.mp = m;
206	greg	2.1	nd.rp = r;
207			setcolor(nd.mcolor, m->oargs.farg[0],
208			m->oargs.farg[1],
209			m->oargs.farg[2]);
210			/* get roughness */
211			nd.specfl = 0;
212	greg	2.18	nd.u_alpha = m->oargs.farg[4];
213			nd.v_alpha = m->oargs.farg[5];
214	greg	2.54	if ((nd.u_alpha <= FTINY) \| (nd.v_alpha <= FTINY))
215	greg	2.10	objerror(m, USER, "roughness too small");
216	greg	2.36
217	greg	2.1	nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */
218			if (nd.pdot < .001)
219			nd.pdot = .001; /* non-zero for diraniso() */
220			multcolor(nd.mcolor, r->pcol); /* modify material color */
221			/* get specular component */
222			if ((nd.rspec = m->oargs.farg[3]) > FTINY) {
223			nd.specfl \|= SP_REFL;
224			/* compute specular color */
225			if (m->otype == MAT_METAL2)
226			copycolor(nd.scolor, nd.mcolor);
227			else
228			setcolor(nd.scolor, 1.0, 1.0, 1.0);
229			scalecolor(nd.scolor, nd.rspec);
230	greg	2.4	/* check threshold */
231	greg	2.25	if (specthresh >= nd.rspec-FTINY)
232	greg	2.4	nd.specfl \|= SP_RBLT;
233	greg	2.6	/* compute refl. direction */
234	greg	2.47	VSUM(nd.vrefl, r->rdir, nd.pnorm, 2.0*nd.pdot);
235	greg	2.6	if (DOT(nd.vrefl, r->ron) <= FTINY) /* penetration? */
236	greg	2.47	VSUM(nd.vrefl, r->rdir, r->ron, 2.0*r->rod);
237	greg	2.1	}
238			/* compute transmission */
239	greg	2.16	if (m->otype == MAT_TRANS2) {
240	greg	2.1	nd.trans = m->oargs.farg[6]*(1.0 - nd.rspec);
241			nd.tspec = nd.trans * m->oargs.farg[7];
242			nd.tdiff = nd.trans - nd.tspec;
243			if (nd.tspec > FTINY) {
244			nd.specfl \|= SP_TRAN;
245	greg	2.4	/* check threshold */
246	greg	2.25	if (specthresh >= nd.tspec-FTINY)
247	greg	2.4	nd.specfl \|= SP_TBLT;
248	greg	2.10	if (DOT(r->pert,r->pert) <= FTINY*FTINY) {
249	greg	2.1	VCOPY(nd.prdir, r->rdir);
250			} else {
251			for (i = 0; i < 3; i++) /* perturb */
252	greg	2.17	nd.prdir[i] = r->rdir[i] - r->pert[i];
253	greg	2.6	if (DOT(nd.prdir, r->ron) < -FTINY)
254			normalize(nd.prdir); /* OK */
255			else
256			VCOPY(nd.prdir, r->rdir);
257	greg	2.1	}
258			}
259			} else
260			nd.tdiff = nd.tspec = nd.trans = 0.0;
261
262			/* diffuse reflection */
263			nd.rdiff = 1.0 - nd.trans - nd.rspec;
264
265	greg	2.39	if (r->ro != NULL && isflat(r->ro->otype))
266	greg	2.4	nd.specfl \|= SP_FLAT;
267
268	greg	2.55	getacoords(&nd); /* set up coordinates */
269	greg	2.1
270	greg	2.57	if (nd.specfl & (SP_REFL\|SP_TRAN))
271	greg	2.55	agaussamp(&nd);
272	greg	2.1
273			if (nd.rdiff > FTINY) { /* ambient from this side */
274	greg	2.43	copycolor(ctmp, nd.mcolor); /* modified by material color */
275	greg	2.52	scalecolor(ctmp, nd.rdiff);
276			if (nd.specfl & SP_RBLT) /* add in specular as well? */
277			addcolor(ctmp, nd.scolor);
278	greg	2.43	multambient(ctmp, r, nd.pnorm);
279	greg	2.1	addcolor(r->rcol, ctmp); /* add to returned color */
280			}
281			if (nd.tdiff > FTINY) { /* ambient from other side */
282	greg	2.31	FVECT bnorm;
283
284	greg	2.1	flipsurface(r);
285	greg	2.31	bnorm[0] = -nd.pnorm[0];
286			bnorm[1] = -nd.pnorm[1];
287			bnorm[2] = -nd.pnorm[2];
288	greg	2.43	copycolor(ctmp, nd.mcolor); /* modified by color */
289	greg	2.4	if (nd.specfl & SP_TBLT)
290			scalecolor(ctmp, nd.trans);
291			else
292			scalecolor(ctmp, nd.tdiff);
293	greg	2.43	multambient(ctmp, r, bnorm);
294	greg	2.1	addcolor(r->rcol, ctmp);
295			flipsurface(r);
296			}
297			/* add direct component */
298			direct(r, diraniso, &nd);
299	greg	2.27
300			return(1);
301	greg	2.1	}
302
303
304	greg	2.34	static void
305	schorsch	2.41	getacoords( /* set up coordinate system */
306	greg	2.54	ANISODAT *np
307	schorsch	2.41	)
308	greg	2.1	{
309	greg	2.54	MFUNC *mf;
310			int i;
311	greg	2.1
312			mf = getfunc(np->mp, 3, 0x7, 1);
313	greg	2.55	setfunc(np->mp, np->rp);
314	greg	2.1	errno = 0;
315			for (i = 0; i < 3; i++)
316			np->u[i] = evalue(mf->ep[i]);
317	greg	2.57	if ((errno == EDOM) \| (errno == ERANGE))
318			np->u[0] = np->u[1] = np->u[2] = 0.0;
319	greg	2.53	if (mf->fxp != &unitxf)
320			multv3(np->u, np->u, mf->fxp->xfm);
321	greg	2.1	fcross(np->v, np->pnorm, np->u);
322			if (normalize(np->v) == 0.0) {
323	greg	2.57	if (fabs(np->u_alpha - np->v_alpha) > 0.001)
324			objerror(np->mp, WARNING, "illegal orientation vector");
325			getperpendicular(np->u, np->pnorm); /* punting */
326			fcross(np->v, np->pnorm, np->u);
327			np->u_alpha = np->v_alpha = sqrt( 0.5 *
328			(np->u_alphanp->u_alpha + np->v_alphanp->v_alpha) );
329			} else
330			fcross(np->u, np->v, np->pnorm);
331	greg	2.1	}
332
333
334	greg	2.34	static void
335	greg	2.46	agaussamp( /* sample anisotropic Gaussian specular */
336	greg	2.54	ANISODAT *np
337	schorsch	2.41	)
338	greg	2.1	{
339			RAY sr;
340			FVECT h;
341			double rv[2];
342			double d, sinp, cosp;
343	greg	2.47	COLOR scol;
344	greg	2.50	int maxiter, ntrials, nstarget, nstaken;
345	greg	2.54	int i;
346	greg	2.1	/* compute reflection */
347	greg	2.4	if ((np->specfl & (SP_REFL\|SP_RBLT)) == SP_REFL &&
348	greg	2.55	rayorigin(&sr, SPECULAR, np->rp, np->scolor) == 0) {
349	greg	2.50	nstarget = 1;
350	greg	2.47	if (specjitter > 1.5) { /* multiple samples? */
351	greg	2.55	nstarget = specjitter*np->rp->rweight + .5;
352	greg	2.50	if (sr.rweight <= minweight*nstarget)
353			nstarget = sr.rweight/minweight;
354			if (nstarget > 1) {
355			d = 1./nstarget;
356			scalecolor(sr.rcoef, d);
357	greg	2.48	sr.rweight *= d;
358	greg	2.47	} else
359	greg	2.50	nstarget = 1;
360	greg	2.47	}
361	greg	2.50	setcolor(scol, 0., 0., 0.);
362	greg	2.51	dimlist[ndims++] = (int)(size_t)np->mp;
363	greg	2.50	maxiter = MAXITER*nstarget;
364			for (nstaken = ntrials = 0; nstaken < nstarget &&
365			ntrials < maxiter; ntrials++) {
366			if (ntrials)
367	greg	2.32	d = frandom();
368			else
369			d = urand(ilhash(dimlist,ndims)+samplendx);
370			multisamp(rv, 2, d);
371			d = 2.0PI rv[0];
372	gwlarson	2.33	cosp = tcos(d) * np->u_alpha;
373			sinp = tsin(d) * np->v_alpha;
374	greg	2.47	d = 1./sqrt(cospcosp + sinpsinp);
375			cosp *= d;
376			sinp *= d;
377			if ((0. <= specjitter) & (specjitter < 1.))
378			rv[1] = 1.0 - specjitter*rv[1];
379	greg	2.32	if (rv[1] <= FTINY)
380			d = 1.0;
381			else
382			d = sqrt(-log(rv[1]) /
383			(cospcosp/(np->u_alphanp->u_alpha) +
384			sinpsinp/(np->v_alphanp->v_alpha)));
385			for (i = 0; i < 3; i++)
386			h[i] = np->pnorm[i] +
387			d(cospnp->u[i] + sinp*np->v[i]);
388	greg	2.55	d = -2.0 * DOT(h, np->rp->rdir) / (1.0 + d*d);
389			VSUM(sr.rdir, np->rp->rdir, h, d);
390	greg	2.50	/* sample rejection test */
391	greg	2.55	if ((d = DOT(sr.rdir, np->rp->ron)) <= FTINY)
392	greg	2.47	continue;
393			checknorm(sr.rdir);
394	greg	2.50	if (nstarget > 1) { /* W-G-M-D adjustment */
395			if (nstaken) rayclear(&sr);
396			rayvalue(&sr);
397	greg	2.55	d = 2./(1. + np->rp->rod/d);
398	greg	2.50	scalecolor(sr.rcol, d);
399			addcolor(scol, sr.rcol);
400			} else {
401			rayvalue(&sr);
402			multcolor(sr.rcol, sr.rcoef);
403	greg	2.55	addcolor(np->rp->rcol, sr.rcol);
404	greg	2.32	}
405	greg	2.50	++nstaken;
406			}
407			if (nstarget > 1) { /* final W-G-M-D weighting */
408			multcolor(scol, sr.rcoef);
409			d = (double)nstarget/ntrials;
410			scalecolor(scol, d);
411	greg	2.55	addcolor(np->rp->rcol, scol);
412	greg	2.32	}
413	greg	2.1	ndims--;
414			}
415			/* compute transmission */
416	greg	2.43	copycolor(sr.rcoef, np->mcolor); /* modify by material color */
417			scalecolor(sr.rcoef, np->tspec);
418	greg	2.7	if ((np->specfl & (SP_TRAN\|SP_TBLT)) == SP_TRAN &&
419	greg	2.55	rayorigin(&sr, SPECULAR, np->rp, sr.rcoef) == 0) {
420	greg	2.50	nstarget = 1;
421	greg	2.47	if (specjitter > 1.5) { /* multiple samples? */
422	greg	2.55	nstarget = specjitter*np->rp->rweight + .5;
423	greg	2.50	if (sr.rweight <= minweight*nstarget)
424			nstarget = sr.rweight/minweight;
425			if (nstarget > 1) {
426			d = 1./nstarget;
427	greg	2.48	scalecolor(sr.rcoef, d);
428			sr.rweight *= d;
429	greg	2.47	} else
430	greg	2.50	nstarget = 1;
431	greg	2.47	}
432	greg	2.51	dimlist[ndims++] = (int)(size_t)np->mp;
433	greg	2.50	maxiter = MAXITER*nstarget;
434			for (nstaken = ntrials = 0; nstaken < nstarget &&
435			ntrials < maxiter; ntrials++) {
436			if (ntrials)
437	greg	2.32	d = frandom();
438			else
439			d = urand(ilhash(dimlist,ndims)+1823+samplendx);
440			multisamp(rv, 2, d);
441			d = 2.0PI rv[0];
442	gwlarson	2.33	cosp = tcos(d) * np->u_alpha;
443			sinp = tsin(d) * np->v_alpha;
444	greg	2.47	d = 1./sqrt(cospcosp + sinpsinp);
445			cosp *= d;
446			sinp *= d;
447			if ((0. <= specjitter) & (specjitter < 1.))
448			rv[1] = 1.0 - specjitter*rv[1];
449	greg	2.32	if (rv[1] <= FTINY)
450			d = 1.0;
451			else
452			d = sqrt(-log(rv[1]) /
453			(cospcosp/(np->u_alphanp->u_alpha) +
454	gwlarson	2.33	sinpsinp/(np->v_alphanp->v_alpha)));
455	greg	2.32	for (i = 0; i < 3; i++)
456			sr.rdir[i] = np->prdir[i] +
457			d(cospnp->u[i] + sinp*np->v[i]);
458	greg	2.55	if (DOT(sr.rdir, np->rp->ron) >= -FTINY)
459	greg	2.47	continue;
460			normalize(sr.rdir); /* OK, normalize */
461	greg	2.50	if (nstaken) /* multi-sampling */
462	greg	2.47	rayclear(&sr);
463			rayvalue(&sr);
464			multcolor(sr.rcol, sr.rcoef);
465	greg	2.55	addcolor(np->rp->rcol, sr.rcol);
466	greg	2.50	++nstaken;
467	greg	2.32	}
468	greg	2.7	ndims--;
469			}
470	greg	2.1	}