src/rt/aniso.c

#ifndef lint
static const char RCSid[] = "$Id: aniso.c,v 2.46 2010/10/01 18:11:18 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.
 *      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-facet-slope v-facet-slope
 *
 *  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 */
#define  SP_BADU        040             /* bad u direction calculation */

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 srcdirf_t diraniso;
static void getacoords(RAY  *r, ANISODAT  *np);
static void agaussamp(RAY  *r, 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 */
)
{
        register 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|SP_BADU)) == 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 */
                h[0] = ldir[0] - np->rp->rdir[0];
                h[1] = ldir[1] - np->rp->rdir[1];
                h[2] = ldir[2] - np->rp->rdir[2];
                                                /* 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|SP_BADU)) == 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" */
                h[0] = ldir[0] - np->prdir[0];
                h[1] = ldir[1] - np->prdir[1];
                h[2] = ldir[2] - np->prdir[2];
                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);
                }
        }
}


extern int
m_aniso(                        /* shade ray that hit something anisotropic */
        register OBJREC  *m,
        register RAY  *r
)
{
        ANISODAT  nd;
        COLOR  ctmp;
        register 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 && m->otype != MAT_TRANS2) {
                        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(r, &nd);                     /* set up coordinates */

        if (nd.specfl & (SP_REFL|SP_TRAN) && !(nd.specfl & SP_BADU))
                agaussamp(r, &nd);

        if (nd.rdiff > FTINY) {         /* ambient from this side */
                copycolor(ctmp, nd.mcolor);     /* modified by material color */
                if (nd.specfl & SP_RBLT)
                        scalecolor(ctmp, 1.0-nd.trans);
                else
                        scalecolor(ctmp, nd.rdiff);
                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 */
        RAY  *r,
        register ANISODAT  *np
)
{
        register MFUNC  *mf;
        register int  i;

        mf = getfunc(np->mp, 3, 0x7, 1);
        setfunc(np->mp, r);
        errno = 0;
        for (i = 0; i < 3; i++)
                np->u[i] = evalue(mf->ep[i]);
        if (errno == EDOM || errno == ERANGE) {
                objerror(np->mp, WARNING, "compute error");
                np->specfl |= SP_BADU;
                return;
        }
        if (mf->f != &unitxf)
                multv3(np->u, np->u, mf->f->xfm);
        fcross(np->v, np->pnorm, np->u);
        if (normalize(np->v) == 0.0) {
                objerror(np->mp, WARNING, "illegal orientation vector");
                np->specfl |= SP_BADU;
                return;
        }
        fcross(np->u, np->v, np->pnorm);
}


static void
agaussamp(              /* sample anisotropic Gaussian specular */
        RAY  *r,
        register ANISODAT  *np
)
{
        RAY  sr;
        FVECT  h;
        double  rv[2];
        double  d, sinp, cosp;
        COLOR   scol;
        int  niter, ns2go;
        register int  i;
                                        /* compute reflection */
        if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL &&
                        rayorigin(&sr, SPECULAR, r, np->scolor) == 0) {
                copycolor(scol, np->scolor);
                ns2go = 1;
                if (specjitter > 1.5) { /* multiple samples? */
                        ns2go = specjitter*r->rweight + .5;
                        if ((d = bright(scol)) <= minweight*ns2go)
                                ns2go = d/minweight;
                        if (ns2go > 1) {
                                d = 1./ns2go;
                                scalecolor(scol, d);
                        } else
                                ns2go = 1;
                }
                dimlist[ndims++] = (int)np->mp;
                for (niter = ns2go*MAXITER; (ns2go > 0) & (niter > 0); niter--) {
                        if (specjitter > 1.5)
                                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, r->rdir) / (1.0 + d*d);
                        if (d <= np->pdot + FTINY)
                                continue;
                        VSUM(sr.rdir, r->rdir, h, d);
                        if (DOT(sr.rdir, r->ron) <= FTINY)
                                continue;
                        checknorm(sr.rdir);
                        if (specjitter > 1.5) { /* adjusted W-G-M-D weight */
                                copycolor(sr.rcoef, scol);
                                d = 2.*(1. - np->pdot/d);
                                scalecolor(sr.rcoef, d);
                                rayclear(&sr);
                        }
                        rayvalue(&sr);
                        multcolor(sr.rcol, sr.rcoef);
                        addcolor(r->rcol, sr.rcol);
                        --ns2go;
                }
                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, r, sr.rcoef) == 0) {
                copycolor(scol, sr.rcoef);
                ns2go = 1;
                if (specjitter > 1.5) { /* multiple samples? */
                        ns2go = specjitter*r->rweight + .5;
                        if ((d = bright(scol)) <= minweight*ns2go)
                                ns2go = d/minweight;
                        if (ns2go > 1) {
                                d = 1./ns2go;
                                scalecolor(scol, d);
                        } else
                                ns2go = 1;
                }
                dimlist[ndims++] = (int)np->mp;
                for (niter = ns2go*MAXITER; (ns2go > 0) & (niter > 0); niter--) {
                        if (specjitter > 1.5)
                                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, r->ron) >= -FTINY)
                                continue;
                        normalize(sr.rdir);     /* OK, normalize */
                        if (specjitter > 1.5) { /* multi-sampling */
                                copycolor(sr.rcoef, scol);
                                rayclear(&sr);
                        }
                        rayvalue(&sr);
                        multcolor(sr.rcol, sr.rcoef);
                        addcolor(r->rcol, sr.rcol);
                        --ns2go;
                }
                ndims--;
        }
}
Revision:	2.47
Committed:	Fri Oct 8 22:08:26 2010 UTC (15 years ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.46:	+68 -32 lines
Log Message:	Changed -sj option to -ss and added multiple specular sampling
#	User	Rev	Content
1	greg	2.1	#ifndef lint
2	greg	2.47	static const char RCSid[] = "$Id: aniso.c,v 2.46 2010/10/01 18:11:18 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			* model described by Ward in Siggraph `92 article.
25	greg	2.1	* We orient the surface towards the incoming ray, so a single
26			* surface can be used to represent an infinitely thin object.
27			*
28			* Arguments for MAT_PLASTIC2 and MAT_METAL2 are:
29			* 4+ ux uy uz funcfile [transform...]
30			* 0
31			* 6 red grn blu specular-frac. u-facet-slope v-facet-slope
32			*
33			* Real arguments for MAT_TRANS2 are:
34			* 8 red grn blu rspec u-rough v-rough trans tspec
35			*/
36
37			/* specularity flags */
38			#define SP_REFL 01 /* has reflected specular component */
39			#define SP_TRAN 02 /* has transmitted specular */
40	greg	2.10	#define SP_FLAT 04 /* reflecting surface is flat */
41			#define SP_RBLT 010 /* reflection below sample threshold */
42			#define SP_TBLT 020 /* transmission below threshold */
43			#define SP_BADU 040 /* bad u direction calculation */
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	schorsch	2.41	static srcdirf_t diraniso;
64			static void getacoords(RAY r, ANISODAT np);
65			static void agaussamp(RAY r, ANISODAT np);
66	greg	2.34
67	greg	2.1
68	greg	2.34	static void
69	schorsch	2.41	diraniso( /* compute source contribution */
70			COLOR cval, /* returned coefficient */
71			void nnp, / material data */
72			FVECT ldir, /* light source direction */
73			double omega /* light source size */
74			)
75	greg	2.1	{
76	schorsch	2.41	register ANISODAT *np = nnp;
77	greg	2.1	double ldot;
78	greg	2.16	double dtmp, dtmp1, dtmp2;
79	greg	2.1	FVECT h;
80			double au2, av2;
81			COLOR ctmp;
82
83			setcolor(cval, 0.0, 0.0, 0.0);
84
85			ldot = DOT(np->pnorm, ldir);
86
87			if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY)
88			return; /* wrong side */
89
90			if (ldot > FTINY && np->rdiff > FTINY) {
91			/*
92			* Compute and add diffuse reflected component to returned
93			* color. The diffuse reflected component will always be
94			* modified by the color of the material.
95			*/
96			copycolor(ctmp, np->mcolor);
97	greg	2.42	dtmp = ldot * omega * np->rdiff * (1.0/PI);
98	greg	2.1	scalecolor(ctmp, dtmp);
99			addcolor(cval, ctmp);
100			}
101	greg	2.10	if (ldot > FTINY && (np->specfl&(SP_REFL\|SP_BADU)) == SP_REFL) {
102	greg	2.1	/*
103			* Compute specular reflection coefficient using
104	greg	2.46	* anisotropic Gaussian distribution model.
105	greg	2.1	*/
106	greg	2.2	/* add source width if flat */
107			if (np->specfl & SP_FLAT)
108	greg	2.42	au2 = av2 = omega * (0.25/PI);
109	greg	2.2	else
110			au2 = av2 = 0.0;
111	greg	2.18	au2 += np->u_alpha*np->u_alpha;
112			av2 += np->v_alpha*np->v_alpha;
113	greg	2.1	/* half vector */
114			h[0] = ldir[0] - np->rp->rdir[0];
115			h[1] = ldir[1] - np->rp->rdir[1];
116			h[2] = ldir[2] - np->rp->rdir[2];
117			/* ellipse */
118	greg	2.16	dtmp1 = DOT(np->u, h);
119			dtmp1 *= dtmp1 / au2;
120	greg	2.1	dtmp2 = DOT(np->v, h);
121			dtmp2 *= dtmp2 / av2;
122	greg	2.46	/* new W-G-M-D model */
123	greg	2.23	dtmp = DOT(np->pnorm, h);
124	greg	2.46	dtmp *= dtmp;
125			dtmp1 = (dtmp1 + dtmp2) / dtmp;
126			dtmp = exp(-dtmp1) * DOT(h,h) /
127			(PI * dtmpdtmp sqrt(au2*av2));
128	greg	2.1	/* worth using? */
129			if (dtmp > FTINY) {
130			copycolor(ctmp, np->scolor);
131	greg	2.46	dtmp = ldot omega;
132	greg	2.1	scalecolor(ctmp, dtmp);
133			addcolor(cval, ctmp);
134			}
135			}
136			if (ldot < -FTINY && np->tdiff > FTINY) {
137			/*
138			* Compute diffuse transmission.
139			*/
140			copycolor(ctmp, np->mcolor);
141	greg	2.42	dtmp = -ldot * omega * np->tdiff * (1.0/PI);
142	greg	2.1	scalecolor(ctmp, dtmp);
143			addcolor(cval, ctmp);
144			}
145	greg	2.10	if (ldot < -FTINY && (np->specfl&(SP_TRAN\|SP_BADU)) == SP_TRAN) {
146	greg	2.1	/*
147			* Compute specular transmission. Specular transmission
148			* is always modified by material color.
149			*/
150			/* roughness + source */
151	greg	2.42	au2 = av2 = omega * (1.0/PI);
152	greg	2.18	au2 += np->u_alpha*np->u_alpha;
153			av2 += np->v_alpha*np->v_alpha;
154	greg	2.16	/* "half vector" */
155			h[0] = ldir[0] - np->prdir[0];
156			h[1] = ldir[1] - np->prdir[1];
157			h[2] = ldir[2] - np->prdir[2];
158	greg	2.19	dtmp = DOT(h,h);
159	greg	2.16	if (dtmp > FTINY*FTINY) {
160	greg	2.19	dtmp1 = DOT(h,np->pnorm);
161			dtmp = 1.0 - dtmp1*dtmp1/dtmp;
162			if (dtmp > FTINY*FTINY) {
163			dtmp1 = DOT(h,np->u);
164	greg	2.23	dtmp1 *= dtmp1 / au2;
165	greg	2.19	dtmp2 = DOT(h,np->v);
166	greg	2.23	dtmp2 *= dtmp2 / av2;
167	greg	2.19	dtmp = (dtmp1 + dtmp2) / dtmp;
168			}
169	greg	2.16	} else
170			dtmp = 0.0;
171	greg	2.46	/* Gaussian */
172	greg	2.44	dtmp = exp(-dtmp) * (1.0/PI) * sqrt(-ldot/(np->pdotau2av2));
173	greg	2.1	/* worth using? */
174			if (dtmp > FTINY) {
175			copycolor(ctmp, np->mcolor);
176	greg	2.16	dtmp = np->tspec omega;
177	greg	2.1	scalecolor(ctmp, dtmp);
178			addcolor(cval, ctmp);
179			}
180			}
181			}
182
183
184	schorsch	2.41	extern int
185			m_aniso( /* shade ray that hit something anisotropic */
186			register OBJREC *m,
187			register RAY *r
188			)
189	greg	2.1	{
190			ANISODAT nd;
191			COLOR ctmp;
192			register int i;
193			/* easy shadow test */
194	greg	2.10	if (r->crtype & SHADOW)
195	greg	2.27	return(1);
196	greg	2.1
197			if (m->oargs.nfargs != (m->otype == MAT_TRANS2 ? 8 : 6))
198			objerror(m, USER, "bad number of real arguments");
199	greg	2.36	/* check for back side */
200			if (r->rod < 0.0) {
201			if (!backvis && m->otype != MAT_TRANS2) {
202			raytrans(r);
203			return(1);
204			}
205			raytexture(r, m->omod);
206			flipsurface(r); /* reorient if backvis */
207			} else
208			raytexture(r, m->omod);
209			/* get material color */
210	greg	2.2	nd.mp = m;
211	greg	2.1	nd.rp = r;
212			setcolor(nd.mcolor, m->oargs.farg[0],
213			m->oargs.farg[1],
214			m->oargs.farg[2]);
215			/* get roughness */
216			nd.specfl = 0;
217	greg	2.18	nd.u_alpha = m->oargs.farg[4];
218			nd.v_alpha = m->oargs.farg[5];
219	greg	2.45	if (nd.u_alpha <= FTINY \|\| nd.v_alpha <= FTINY)
220	greg	2.10	objerror(m, USER, "roughness too small");
221	greg	2.36
222	greg	2.1	nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */
223			if (nd.pdot < .001)
224			nd.pdot = .001; /* non-zero for diraniso() */
225			multcolor(nd.mcolor, r->pcol); /* modify material color */
226			/* get specular component */
227			if ((nd.rspec = m->oargs.farg[3]) > FTINY) {
228			nd.specfl \|= SP_REFL;
229			/* compute specular color */
230			if (m->otype == MAT_METAL2)
231			copycolor(nd.scolor, nd.mcolor);
232			else
233			setcolor(nd.scolor, 1.0, 1.0, 1.0);
234			scalecolor(nd.scolor, nd.rspec);
235	greg	2.4	/* check threshold */
236	greg	2.25	if (specthresh >= nd.rspec-FTINY)
237	greg	2.4	nd.specfl \|= SP_RBLT;
238	greg	2.6	/* compute refl. direction */
239	greg	2.47	VSUM(nd.vrefl, r->rdir, nd.pnorm, 2.0*nd.pdot);
240	greg	2.6	if (DOT(nd.vrefl, r->ron) <= FTINY) /* penetration? */
241	greg	2.47	VSUM(nd.vrefl, r->rdir, r->ron, 2.0*r->rod);
242	greg	2.1	}
243			/* compute transmission */
244	greg	2.16	if (m->otype == MAT_TRANS2) {
245	greg	2.1	nd.trans = m->oargs.farg[6]*(1.0 - nd.rspec);
246			nd.tspec = nd.trans * m->oargs.farg[7];
247			nd.tdiff = nd.trans - nd.tspec;
248			if (nd.tspec > FTINY) {
249			nd.specfl \|= SP_TRAN;
250	greg	2.4	/* check threshold */
251	greg	2.25	if (specthresh >= nd.tspec-FTINY)
252	greg	2.4	nd.specfl \|= SP_TBLT;
253	greg	2.10	if (DOT(r->pert,r->pert) <= FTINY*FTINY) {
254	greg	2.1	VCOPY(nd.prdir, r->rdir);
255			} else {
256			for (i = 0; i < 3; i++) /* perturb */
257	greg	2.17	nd.prdir[i] = r->rdir[i] - r->pert[i];
258	greg	2.6	if (DOT(nd.prdir, r->ron) < -FTINY)
259			normalize(nd.prdir); /* OK */
260			else
261			VCOPY(nd.prdir, r->rdir);
262	greg	2.1	}
263			}
264			} else
265			nd.tdiff = nd.tspec = nd.trans = 0.0;
266
267			/* diffuse reflection */
268			nd.rdiff = 1.0 - nd.trans - nd.rspec;
269
270	greg	2.39	if (r->ro != NULL && isflat(r->ro->otype))
271	greg	2.4	nd.specfl \|= SP_FLAT;
272
273	greg	2.1	getacoords(r, &nd); /* set up coordinates */
274
275	greg	2.10	if (nd.specfl & (SP_REFL\|SP_TRAN) && !(nd.specfl & SP_BADU))
276	greg	2.1	agaussamp(r, &nd);
277
278			if (nd.rdiff > FTINY) { /* ambient from this side */
279	greg	2.43	copycolor(ctmp, nd.mcolor); /* modified by material color */
280	greg	2.4	if (nd.specfl & SP_RBLT)
281			scalecolor(ctmp, 1.0-nd.trans);
282			else
283			scalecolor(ctmp, nd.rdiff);
284	greg	2.43	multambient(ctmp, r, nd.pnorm);
285	greg	2.1	addcolor(r->rcol, ctmp); /* add to returned color */
286			}
287			if (nd.tdiff > FTINY) { /* ambient from other side */
288	greg	2.31	FVECT bnorm;
289
290	greg	2.1	flipsurface(r);
291	greg	2.31	bnorm[0] = -nd.pnorm[0];
292			bnorm[1] = -nd.pnorm[1];
293			bnorm[2] = -nd.pnorm[2];
294	greg	2.43	copycolor(ctmp, nd.mcolor); /* modified by color */
295	greg	2.4	if (nd.specfl & SP_TBLT)
296			scalecolor(ctmp, nd.trans);
297			else
298			scalecolor(ctmp, nd.tdiff);
299	greg	2.43	multambient(ctmp, r, bnorm);
300	greg	2.1	addcolor(r->rcol, ctmp);
301			flipsurface(r);
302			}
303			/* add direct component */
304			direct(r, diraniso, &nd);
305	greg	2.27
306			return(1);
307	greg	2.1	}
308
309
310	greg	2.34	static void
311	schorsch	2.41	getacoords( /* set up coordinate system */
312			RAY *r,
313			register ANISODAT *np
314			)
315	greg	2.1	{
316			register MFUNC *mf;
317			register int i;
318
319			mf = getfunc(np->mp, 3, 0x7, 1);
320			setfunc(np->mp, r);
321			errno = 0;
322			for (i = 0; i < 3; i++)
323			np->u[i] = evalue(mf->ep[i]);
324	greg	2.37	if (errno == EDOM \|\| errno == ERANGE) {
325	greg	2.1	objerror(np->mp, WARNING, "compute error");
326			np->specfl \|= SP_BADU;
327			return;
328			}
329	greg	2.16	if (mf->f != &unitxf)
330			multv3(np->u, np->u, mf->f->xfm);
331	greg	2.1	fcross(np->v, np->pnorm, np->u);
332			if (normalize(np->v) == 0.0) {
333			objerror(np->mp, WARNING, "illegal orientation vector");
334			np->specfl \|= SP_BADU;
335			return;
336			}
337			fcross(np->u, np->v, np->pnorm);
338			}
339
340
341	greg	2.34	static void
342	greg	2.46	agaussamp( /* sample anisotropic Gaussian specular */
343	schorsch	2.41	RAY *r,
344			register ANISODAT *np
345			)
346	greg	2.1	{
347			RAY sr;
348			FVECT h;
349			double rv[2];
350			double d, sinp, cosp;
351	greg	2.47	COLOR scol;
352			int niter, ns2go;
353	greg	2.1	register int i;
354			/* compute reflection */
355	greg	2.4	if ((np->specfl & (SP_REFL\|SP_RBLT)) == SP_REFL &&
356	greg	2.43	rayorigin(&sr, SPECULAR, r, np->scolor) == 0) {
357	greg	2.47	copycolor(scol, np->scolor);
358			ns2go = 1;
359			if (specjitter > 1.5) { /* multiple samples? */
360			ns2go = specjitter*r->rweight + .5;
361			if ((d = bright(scol)) <= minweight*ns2go)
362			ns2go = d/minweight;
363			if (ns2go > 1) {
364			d = 1./ns2go;
365			scalecolor(scol, d);
366			} else
367			ns2go = 1;
368			}
369	greg	2.1	dimlist[ndims++] = (int)np->mp;
370	greg	2.47	for (niter = ns2go*MAXITER; (ns2go > 0) & (niter > 0); niter--) {
371			if (specjitter > 1.5)
372	greg	2.32	d = frandom();
373			else
374			d = urand(ilhash(dimlist,ndims)+samplendx);
375			multisamp(rv, 2, d);
376			d = 2.0PI rv[0];
377	gwlarson	2.33	cosp = tcos(d) * np->u_alpha;
378			sinp = tsin(d) * np->v_alpha;
379	greg	2.47	d = 1./sqrt(cospcosp + sinpsinp);
380			cosp *= d;
381			sinp *= d;
382			if ((0. <= specjitter) & (specjitter < 1.))
383			rv[1] = 1.0 - specjitter*rv[1];
384	greg	2.32	if (rv[1] <= FTINY)
385			d = 1.0;
386			else
387			d = sqrt(-log(rv[1]) /
388			(cospcosp/(np->u_alphanp->u_alpha) +
389			sinpsinp/(np->v_alphanp->v_alpha)));
390			for (i = 0; i < 3; i++)
391			h[i] = np->pnorm[i] +
392			d(cospnp->u[i] + sinp*np->v[i]);
393			d = -2.0 * DOT(h, r->rdir) / (1.0 + d*d);
394	greg	2.47	if (d <= np->pdot + FTINY)
395			continue;
396			VSUM(sr.rdir, r->rdir, h, d);
397			if (DOT(sr.rdir, r->ron) <= FTINY)
398			continue;
399			checknorm(sr.rdir);
400			if (specjitter > 1.5) { /* adjusted W-G-M-D weight */
401			copycolor(sr.rcoef, scol);
402			d = 2.*(1. - np->pdot/d);
403			scalecolor(sr.rcoef, d);
404			rayclear(&sr);
405	greg	2.32	}
406	greg	2.47	rayvalue(&sr);
407			multcolor(sr.rcol, sr.rcoef);
408			addcolor(r->rcol, sr.rcol);
409			--ns2go;
410	greg	2.32	}
411	greg	2.1	ndims--;
412			}
413			/* compute transmission */
414	greg	2.43	copycolor(sr.rcoef, np->mcolor); /* modify by material color */
415			scalecolor(sr.rcoef, np->tspec);
416	greg	2.7	if ((np->specfl & (SP_TRAN\|SP_TBLT)) == SP_TRAN &&
417	greg	2.43	rayorigin(&sr, SPECULAR, r, sr.rcoef) == 0) {
418	greg	2.47	copycolor(scol, sr.rcoef);
419			ns2go = 1;
420			if (specjitter > 1.5) { /* multiple samples? */
421			ns2go = specjitter*r->rweight + .5;
422			if ((d = bright(scol)) <= minweight*ns2go)
423			ns2go = d/minweight;
424			if (ns2go > 1) {
425			d = 1./ns2go;
426			scalecolor(scol, d);
427			} else
428			ns2go = 1;
429			}
430	greg	2.7	dimlist[ndims++] = (int)np->mp;
431	greg	2.47	for (niter = ns2go*MAXITER; (ns2go > 0) & (niter > 0); niter--) {
432			if (specjitter > 1.5)
433	greg	2.32	d = frandom();
434			else
435			d = urand(ilhash(dimlist,ndims)+1823+samplendx);
436			multisamp(rv, 2, d);
437			d = 2.0PI rv[0];
438	gwlarson	2.33	cosp = tcos(d) * np->u_alpha;
439			sinp = tsin(d) * np->v_alpha;
440	greg	2.47	d = 1./sqrt(cospcosp + sinpsinp);
441			cosp *= d;
442			sinp *= d;
443			if ((0. <= specjitter) & (specjitter < 1.))
444			rv[1] = 1.0 - specjitter*rv[1];
445	greg	2.32	if (rv[1] <= FTINY)
446			d = 1.0;
447			else
448			d = sqrt(-log(rv[1]) /
449			(cospcosp/(np->u_alphanp->u_alpha) +
450	gwlarson	2.33	sinpsinp/(np->v_alphanp->v_alpha)));
451	greg	2.32	for (i = 0; i < 3; i++)
452			sr.rdir[i] = np->prdir[i] +
453			d(cospnp->u[i] + sinp*np->v[i]);
454	greg	2.47	if (DOT(sr.rdir, r->ron) >= -FTINY)
455			continue;
456			normalize(sr.rdir); /* OK, normalize */
457			if (specjitter > 1.5) { /* multi-sampling */
458			copycolor(sr.rcoef, scol);
459			rayclear(&sr);
460	greg	2.32	}
461	greg	2.47	rayvalue(&sr);
462			multcolor(sr.rcol, sr.rcoef);
463			addcolor(r->rcol, sr.rcol);
464			--ns2go;
465	greg	2.32	}
466	greg	2.7	ndims--;
467			}
468	greg	2.1	}