src/rt/aniso.c

#ifndef lint
static const char RCSid[] = "$Id: aniso.c,v 2.59 2015/05/21 05:54:54 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->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_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->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, 1);  /* 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:	2.60
Committed:	Tue May 26 13:21:07 2015 UTC (8 years, 11 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.59:	+2 -10 lines
Log Message:	Removed deprecated ambRayInPmap() macro from code
#	User	Rev	Content
1	greg	2.1	#ifndef lint
2	greg	2.60	static const char RCSid[] = "$Id: aniso.c,v 2.59 2015/05/21 05:54:54 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	2.58
101			if ((ldot < -FTINY) & (np->tdiff > FTINY)) {
102			/*
103			* Compute diffuse transmission.
104			*/
105			copycolor(ctmp, np->mcolor);
106			dtmp = -ldot * omega * np->tdiff * (1.0/PI);
107			scalecolor(ctmp, dtmp);
108			addcolor(cval, ctmp);
109			}
110
111	greg	2.57	if (ldot > FTINY && np->specfl&SP_REFL) {
112	greg	2.1	/*
113			* Compute specular reflection coefficient using
114	greg	2.46	* anisotropic Gaussian distribution model.
115	greg	2.1	*/
116	greg	2.2	/* add source width if flat */
117			if (np->specfl & SP_FLAT)
118	greg	2.42	au2 = av2 = omega * (0.25/PI);
119	greg	2.2	else
120			au2 = av2 = 0.0;
121	greg	2.18	au2 += np->u_alpha*np->u_alpha;
122			av2 += np->v_alpha*np->v_alpha;
123	greg	2.1	/* half vector */
124	greg	2.54	VSUB(h, ldir, np->rp->rdir);
125	greg	2.1	/* ellipse */
126	greg	2.16	dtmp1 = DOT(np->u, h);
127			dtmp1 *= dtmp1 / au2;
128	greg	2.1	dtmp2 = DOT(np->v, h);
129			dtmp2 *= dtmp2 / av2;
130	greg	2.46	/* new W-G-M-D model */
131	greg	2.23	dtmp = DOT(np->pnorm, h);
132	greg	2.46	dtmp *= dtmp;
133			dtmp1 = (dtmp1 + dtmp2) / dtmp;
134			dtmp = exp(-dtmp1) * DOT(h,h) /
135			(PI * dtmpdtmp sqrt(au2*av2));
136	greg	2.1	/* worth using? */
137			if (dtmp > FTINY) {
138			copycolor(ctmp, np->scolor);
139	greg	2.46	dtmp = ldot omega;
140	greg	2.1	scalecolor(ctmp, dtmp);
141			addcolor(cval, ctmp);
142			}
143			}
144	greg	2.58
145	greg	2.57	if (ldot < -FTINY && np->specfl&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	greg	2.54	VSUB(h, ldir, np->prdir);
156	greg	2.19	dtmp = DOT(h,h);
157	greg	2.16	if (dtmp > FTINY*FTINY) {
158	greg	2.19	dtmp1 = DOT(h,np->pnorm);
159			dtmp = 1.0 - dtmp1*dtmp1/dtmp;
160			if (dtmp > FTINY*FTINY) {
161			dtmp1 = DOT(h,np->u);
162	greg	2.23	dtmp1 *= dtmp1 / au2;
163	greg	2.19	dtmp2 = DOT(h,np->v);
164	greg	2.23	dtmp2 *= dtmp2 / av2;
165	greg	2.19	dtmp = (dtmp1 + dtmp2) / dtmp;
166			}
167	greg	2.16	} else
168			dtmp = 0.0;
169	greg	2.46	/* Gaussian */
170	greg	2.44	dtmp = exp(-dtmp) * (1.0/PI) * sqrt(-ldot/(np->pdotau2av2));
171	greg	2.1	/* worth using? */
172			if (dtmp > FTINY) {
173			copycolor(ctmp, np->mcolor);
174	greg	2.16	dtmp = np->tspec omega;
175	greg	2.1	scalecolor(ctmp, dtmp);
176			addcolor(cval, ctmp);
177			}
178			}
179			}
180
181
182	greg	2.54	int
183	schorsch	2.41	m_aniso( /* shade ray that hit something anisotropic */
184	greg	2.54	OBJREC *m,
185			RAY *r
186	schorsch	2.41	)
187	greg	2.1	{
188			ANISODAT nd;
189			COLOR ctmp;
190	greg	2.54	int i;
191	greg	2.1	/* easy shadow test */
192	greg	2.10	if (r->crtype & SHADOW)
193	greg	2.27	return(1);
194	greg	2.1
195			if (m->oargs.nfargs != (m->otype == MAT_TRANS2 ? 8 : 6))
196			objerror(m, USER, "bad number of real arguments");
197	greg	2.36	/* check for back side */
198			if (r->rod < 0.0) {
199	greg	2.56	if (!backvis) {
200	greg	2.36	raytrans(r);
201			return(1);
202			}
203			raytexture(r, m->omod);
204			flipsurface(r); /* reorient if backvis */
205			} else
206			raytexture(r, m->omod);
207			/* get material color */
208	greg	2.2	nd.mp = m;
209	greg	2.1	nd.rp = r;
210			setcolor(nd.mcolor, m->oargs.farg[0],
211			m->oargs.farg[1],
212			m->oargs.farg[2]);
213			/* get roughness */
214			nd.specfl = 0;
215	greg	2.18	nd.u_alpha = m->oargs.farg[4];
216			nd.v_alpha = m->oargs.farg[5];
217	greg	2.54	if ((nd.u_alpha <= FTINY) \| (nd.v_alpha <= FTINY))
218	greg	2.10	objerror(m, USER, "roughness too small");
219	greg	2.36
220	greg	2.1	nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */
221			if (nd.pdot < .001)
222			nd.pdot = .001; /* non-zero for diraniso() */
223			multcolor(nd.mcolor, r->pcol); /* modify material color */
224			/* get specular component */
225			if ((nd.rspec = m->oargs.farg[3]) > FTINY) {
226			nd.specfl \|= SP_REFL;
227			/* compute specular color */
228			if (m->otype == MAT_METAL2)
229			copycolor(nd.scolor, nd.mcolor);
230			else
231			setcolor(nd.scolor, 1.0, 1.0, 1.0);
232			scalecolor(nd.scolor, nd.rspec);
233	greg	2.4	/* check threshold */
234	greg	2.25	if (specthresh >= nd.rspec-FTINY)
235	greg	2.4	nd.specfl \|= SP_RBLT;
236	greg	2.6	/* compute refl. direction */
237	greg	2.47	VSUM(nd.vrefl, r->rdir, nd.pnorm, 2.0*nd.pdot);
238	greg	2.6	if (DOT(nd.vrefl, r->ron) <= FTINY) /* penetration? */
239	greg	2.47	VSUM(nd.vrefl, r->rdir, r->ron, 2.0*r->rod);
240	greg	2.1	}
241			/* compute transmission */
242	greg	2.16	if (m->otype == MAT_TRANS2) {
243	greg	2.1	nd.trans = m->oargs.farg[6]*(1.0 - nd.rspec);
244			nd.tspec = nd.trans * m->oargs.farg[7];
245			nd.tdiff = nd.trans - nd.tspec;
246			if (nd.tspec > FTINY) {
247			nd.specfl \|= SP_TRAN;
248	greg	2.4	/* check threshold */
249	greg	2.25	if (specthresh >= nd.tspec-FTINY)
250	greg	2.4	nd.specfl \|= SP_TBLT;
251	greg	2.10	if (DOT(r->pert,r->pert) <= FTINY*FTINY) {
252	greg	2.1	VCOPY(nd.prdir, r->rdir);
253			} else {
254			for (i = 0; i < 3; i++) /* perturb */
255	greg	2.17	nd.prdir[i] = r->rdir[i] - r->pert[i];
256	greg	2.6	if (DOT(nd.prdir, r->ron) < -FTINY)
257			normalize(nd.prdir); /* OK */
258			else
259			VCOPY(nd.prdir, r->rdir);
260	greg	2.1	}
261			}
262			} else
263			nd.tdiff = nd.tspec = nd.trans = 0.0;
264
265			/* diffuse reflection */
266			nd.rdiff = 1.0 - nd.trans - nd.rspec;
267
268	greg	2.39	if (r->ro != NULL && isflat(r->ro->otype))
269	greg	2.4	nd.specfl \|= SP_FLAT;
270
271	greg	2.55	getacoords(&nd); /* set up coordinates */
272	greg	2.1
273	greg	2.60	if (nd.specfl & (SP_REFL\|SP_TRAN))
274	greg	2.55	agaussamp(&nd);
275	greg	2.1
276			if (nd.rdiff > FTINY) { /* ambient from this side */
277	greg	2.43	copycolor(ctmp, nd.mcolor); /* modified by material color */
278	greg	2.52	scalecolor(ctmp, nd.rdiff);
279			if (nd.specfl & SP_RBLT) /* add in specular as well? */
280			addcolor(ctmp, nd.scolor);
281	greg	2.43	multambient(ctmp, r, nd.pnorm);
282	greg	2.1	addcolor(r->rcol, ctmp); /* add to returned color */
283			}
284	greg	2.58
285	greg	2.1	if (nd.tdiff > FTINY) { /* ambient from other side */
286	greg	2.31	FVECT bnorm;
287
288	greg	2.1	flipsurface(r);
289	greg	2.31	bnorm[0] = -nd.pnorm[0];
290			bnorm[1] = -nd.pnorm[1];
291			bnorm[2] = -nd.pnorm[2];
292	greg	2.43	copycolor(ctmp, nd.mcolor); /* modified by color */
293	greg	2.4	if (nd.specfl & SP_TBLT)
294			scalecolor(ctmp, nd.trans);
295			else
296			scalecolor(ctmp, nd.tdiff);
297	greg	2.43	multambient(ctmp, r, bnorm);
298	greg	2.1	addcolor(r->rcol, ctmp);
299			flipsurface(r);
300			}
301			/* add direct component */
302			direct(r, diraniso, &nd);
303	greg	2.27
304			return(1);
305	greg	2.1	}
306
307	greg	2.34	static void
308	schorsch	2.41	getacoords( /* set up coordinate system */
309	greg	2.54	ANISODAT *np
310	schorsch	2.41	)
311	greg	2.1	{
312	greg	2.54	MFUNC *mf;
313			int i;
314	greg	2.1
315			mf = getfunc(np->mp, 3, 0x7, 1);
316	greg	2.55	setfunc(np->mp, np->rp);
317	greg	2.1	errno = 0;
318			for (i = 0; i < 3; i++)
319			np->u[i] = evalue(mf->ep[i]);
320	greg	2.57	if ((errno == EDOM) \| (errno == ERANGE))
321			np->u[0] = np->u[1] = np->u[2] = 0.0;
322	greg	2.53	if (mf->fxp != &unitxf)
323			multv3(np->u, np->u, mf->fxp->xfm);
324	greg	2.1	fcross(np->v, np->pnorm, np->u);
325			if (normalize(np->v) == 0.0) {
326	greg	2.57	if (fabs(np->u_alpha - np->v_alpha) > 0.001)
327			objerror(np->mp, WARNING, "illegal orientation vector");
328	greg	2.59	getperpendicular(np->u, np->pnorm, 1); /* punting */
329	greg	2.57	fcross(np->v, np->pnorm, np->u);
330			np->u_alpha = np->v_alpha = sqrt( 0.5 *
331			(np->u_alphanp->u_alpha + np->v_alphanp->v_alpha) );
332			} else
333			fcross(np->u, np->v, np->pnorm);
334	greg	2.1	}
335
336
337	greg	2.34	static void
338	greg	2.46	agaussamp( /* sample anisotropic Gaussian specular */
339	greg	2.54	ANISODAT *np
340	schorsch	2.41	)
341	greg	2.1	{
342			RAY sr;
343			FVECT h;
344			double rv[2];
345			double d, sinp, cosp;
346	greg	2.47	COLOR scol;
347	greg	2.50	int maxiter, ntrials, nstarget, nstaken;
348	greg	2.54	int i;
349	greg	2.1	/* compute reflection */
350	greg	2.4	if ((np->specfl & (SP_REFL\|SP_RBLT)) == SP_REFL &&
351	greg	2.55	rayorigin(&sr, SPECULAR, np->rp, np->scolor) == 0) {
352	greg	2.50	nstarget = 1;
353	greg	2.47	if (specjitter > 1.5) { /* multiple samples? */
354	greg	2.55	nstarget = specjitter*np->rp->rweight + .5;
355	greg	2.50	if (sr.rweight <= minweight*nstarget)
356			nstarget = sr.rweight/minweight;
357			if (nstarget > 1) {
358			d = 1./nstarget;
359			scalecolor(sr.rcoef, d);
360	greg	2.48	sr.rweight *= d;
361	greg	2.47	} else
362	greg	2.50	nstarget = 1;
363	greg	2.47	}
364	greg	2.50	setcolor(scol, 0., 0., 0.);
365	greg	2.51	dimlist[ndims++] = (int)(size_t)np->mp;
366	greg	2.50	maxiter = MAXITER*nstarget;
367			for (nstaken = ntrials = 0; nstaken < nstarget &&
368			ntrials < maxiter; ntrials++) {
369			if (ntrials)
370	greg	2.32	d = frandom();
371			else
372			d = urand(ilhash(dimlist,ndims)+samplendx);
373			multisamp(rv, 2, d);
374			d = 2.0PI rv[0];
375	gwlarson	2.33	cosp = tcos(d) * np->u_alpha;
376			sinp = tsin(d) * np->v_alpha;
377	greg	2.47	d = 1./sqrt(cospcosp + sinpsinp);
378			cosp *= d;
379			sinp *= d;
380			if ((0. <= specjitter) & (specjitter < 1.))
381			rv[1] = 1.0 - specjitter*rv[1];
382	greg	2.32	if (rv[1] <= FTINY)
383			d = 1.0;
384			else
385			d = sqrt(-log(rv[1]) /
386			(cospcosp/(np->u_alphanp->u_alpha) +
387			sinpsinp/(np->v_alphanp->v_alpha)));
388			for (i = 0; i < 3; i++)
389			h[i] = np->pnorm[i] +
390			d(cospnp->u[i] + sinp*np->v[i]);
391	greg	2.55	d = -2.0 * DOT(h, np->rp->rdir) / (1.0 + d*d);
392			VSUM(sr.rdir, np->rp->rdir, h, d);
393	greg	2.50	/* sample rejection test */
394	greg	2.55	if ((d = DOT(sr.rdir, np->rp->ron)) <= FTINY)
395	greg	2.47	continue;
396			checknorm(sr.rdir);
397	greg	2.50	if (nstarget > 1) { /* W-G-M-D adjustment */
398			if (nstaken) rayclear(&sr);
399			rayvalue(&sr);
400	greg	2.55	d = 2./(1. + np->rp->rod/d);
401	greg	2.50	scalecolor(sr.rcol, d);
402			addcolor(scol, sr.rcol);
403			} else {
404			rayvalue(&sr);
405			multcolor(sr.rcol, sr.rcoef);
406	greg	2.55	addcolor(np->rp->rcol, sr.rcol);
407	greg	2.32	}
408	greg	2.50	++nstaken;
409			}
410			if (nstarget > 1) { /* final W-G-M-D weighting */
411			multcolor(scol, sr.rcoef);
412			d = (double)nstarget/ntrials;
413			scalecolor(scol, d);
414	greg	2.55	addcolor(np->rp->rcol, scol);
415	greg	2.32	}
416	greg	2.1	ndims--;
417			}
418			/* compute transmission */
419	greg	2.43	copycolor(sr.rcoef, np->mcolor); /* modify by material color */
420			scalecolor(sr.rcoef, np->tspec);
421	greg	2.7	if ((np->specfl & (SP_TRAN\|SP_TBLT)) == SP_TRAN &&
422	greg	2.55	rayorigin(&sr, SPECULAR, np->rp, sr.rcoef) == 0) {
423	greg	2.50	nstarget = 1;
424	greg	2.47	if (specjitter > 1.5) { /* multiple samples? */
425	greg	2.55	nstarget = specjitter*np->rp->rweight + .5;
426	greg	2.50	if (sr.rweight <= minweight*nstarget)
427			nstarget = sr.rweight/minweight;
428			if (nstarget > 1) {
429			d = 1./nstarget;
430	greg	2.48	scalecolor(sr.rcoef, d);
431			sr.rweight *= d;
432	greg	2.47	} else
433	greg	2.50	nstarget = 1;
434	greg	2.47	}
435	greg	2.51	dimlist[ndims++] = (int)(size_t)np->mp;
436	greg	2.50	maxiter = MAXITER*nstarget;
437			for (nstaken = ntrials = 0; nstaken < nstarget &&
438			ntrials < maxiter; ntrials++) {
439			if (ntrials)
440	greg	2.32	d = frandom();
441			else
442			d = urand(ilhash(dimlist,ndims)+1823+samplendx);
443			multisamp(rv, 2, d);
444			d = 2.0PI rv[0];
445	gwlarson	2.33	cosp = tcos(d) * np->u_alpha;
446			sinp = tsin(d) * np->v_alpha;
447	greg	2.47	d = 1./sqrt(cospcosp + sinpsinp);
448			cosp *= d;
449			sinp *= d;
450			if ((0. <= specjitter) & (specjitter < 1.))
451			rv[1] = 1.0 - specjitter*rv[1];
452	greg	2.32	if (rv[1] <= FTINY)
453			d = 1.0;
454			else
455			d = sqrt(-log(rv[1]) /
456			(cospcosp/(np->u_alphanp->u_alpha) +
457	gwlarson	2.33	sinpsinp/(np->v_alphanp->v_alpha)));
458	greg	2.32	for (i = 0; i < 3; i++)
459			sr.rdir[i] = np->prdir[i] +
460			d(cospnp->u[i] + sinp*np->v[i]);
461	greg	2.55	if (DOT(sr.rdir, np->rp->ron) >= -FTINY)
462	greg	2.47	continue;
463			normalize(sr.rdir); /* OK, normalize */
464	greg	2.50	if (nstaken) /* multi-sampling */
465	greg	2.47	rayclear(&sr);
466			rayvalue(&sr);
467			multcolor(sr.rcol, sr.rcoef);
468	greg	2.55	addcolor(np->rp->rcol, sr.rcol);
469	greg	2.50	++nstaken;
470	greg	2.32	}
471	greg	2.7	ndims--;
472			}
473	greg	2.1	}