src/rt/aniso.c

#ifndef lint
static const char RCSid[] = "$Id: aniso.c,v 2.66 2024/12/06 01:34:21 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"
#include  "pmapmat.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 */
        SCOLOR  mcolor;         /* color of this material */
        SCOLOR  scolor;         /* color of specular component */
        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 */
        SCOLOR  scval,                  /* 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;
        SCOLOR  sctmp;

        scolorblack(scval);

        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.
                 */
                copyscolor(sctmp, np->mcolor);
                dtmp = ldot * omega * np->rdiff * (1.0/PI);
                scalescolor(sctmp, dtmp);
                saddscolor(scval, sctmp);
        }

        if ((ldot < -FTINY) & (np->tdiff > FTINY)) {
                /*
                 *  Compute diffuse transmission.
                 */
                copyscolor(sctmp, np->mcolor);
                dtmp = -ldot * omega * np->tdiff * (1.0/PI);
                scalescolor(sctmp, dtmp);
                saddscolor(scval, sctmp);
        }
        
        if (ambRayInPmap(np->rp))
                return;         /* specular accounted for in photon map */

        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) {
                        copyscolor(sctmp, np->scolor);
                        dtmp *= ldot * omega;
                        scalescolor(sctmp, dtmp);
                        saddscolor(scval, sctmp);
                }
        }
        
        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;
                        dtmp = exp(-dtmp);
                } else
                        dtmp = 1.0;
                                                /* Gaussian */
                dtmp *= (1.0/PI) * sqrt(-ldot/(np->pdot*au2*av2));
                                                /* worth using? */
                if (dtmp > FTINY) {
                        copyscolor(sctmp, np->mcolor);
                        dtmp *= np->tspec * omega;
                        scalescolor(sctmp, dtmp);
                        saddscolor(scval, sctmp);
                }
        }
}


int
m_aniso(                        /* shade ray that hit something anisotropic */
        OBJREC  *m,
        RAY  *r
)
{
        ANISODAT  nd;
        SCOLOR  sctmp;
        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;
        setscolor(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() */
        smultscolor(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)
                        copyscolor(nd.scolor, nd.mcolor);
                else
                        setscolor(nd.scolor, 1.0, 1.0, 1.0);
                scalescolor(nd.scolor, nd.rspec);
                                                /* check threshold */
                if (specthresh >= nd.rspec-FTINY)
                        nd.specfl |= SP_RBLT;
        }
                                                /* 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) &&
                        DOT(r->pert,r->pert) <= FTINY*FTINY)
                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 */
                copyscolor(sctmp, nd.mcolor);   /* modified by material color */
                scalescolor(sctmp, nd.rdiff);
                if (nd.specfl & SP_RBLT)        /* add in specular as well? */
                        saddscolor(sctmp, nd.scolor);
                multambient(sctmp, r, nd.pnorm);
                saddscolor(r->rcol, sctmp);     /* add to returned color */
        }
        
        if (nd.tdiff > FTINY) {         /* ambient from other side */
                FVECT  bnorm;
                bnorm[0] = -nd.pnorm[0];
                bnorm[1] = -nd.pnorm[1];
                bnorm[2] = -nd.pnorm[2];
                copyscolor(sctmp, nd.mcolor);   /* modified by color */
                if (nd.specfl & SP_TBLT) {
                        scalescolor(sctmp, nd.trans);
                } else {
                        scalescolor(sctmp, nd.tdiff);
                }
                multambient(sctmp, r, bnorm);
                saddscolor(r->rcol, sctmp);
        }
                                        /* 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;
        else 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;
        int  maxiter, ntrials, nstarget, nstaken;
        int  i;
                                        /* compute reflection */
        if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL &&
                        rayorigin(&sr, RSPECULAR, np->rp, np->scolor) == 0) {
                SCOLOR  scol;
                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;
                                scalescolor(sr.rcoef, d);
                                sr.rweight *= d;
                        } else
                                nstarget = 1;
                }
                scolorblack(scol);
                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];
                        d = (rv[1] <= FTINY) ? 1.0 : 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);
                                scalescolor(sr.rcol, d);
                                saddscolor(scol, sr.rcol);
                        } else {
                                rayvalue(&sr);
                                smultscolor(sr.rcol, sr.rcoef);
                                saddscolor(np->rp->rcol, sr.rcol);
                        }
                        ++nstaken;
                }
                if (nstarget > 1) {             /* final W-G-M-D weighting */
                        smultscolor(scol, sr.rcoef);
                        d = (double)nstarget/ntrials;
                        scalescolor(scol, d);
                        saddscolor(np->rp->rcol, scol);
                }
                ndims--;
        }
                                        /* compute transmission */
        copyscolor(sr.rcoef, np->mcolor);               /* modify by material color */
        scalescolor(sr.rcoef, np->tspec);
        if ((np->specfl & (SP_TRAN|SP_TBLT)) == SP_TRAN &&
                        rayorigin(&sr, TSPECULAR, 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;
                                scalescolor(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;       /* reject sample */
                        normalize(sr.rdir);     /* OK, normalize */
                        if (nstaken)            /* multi-sampling */
                                rayclear(&sr);
                        rayvalue(&sr);
                        smultscolor(sr.rcol, sr.rcoef);
                        saddscolor(np->rp->rcol, sr.rcol);
                        ++nstaken;
                }
                ndims--;
        }
}
Revision:	2.67
Committed:	Thu Dec 19 23:25:28 2024 UTC (10 months, 1 week ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.66:	+3 -2 lines
Log Message:	fix: Issue with textured surfaces and source scattering
#	User	Rev	Content
1	greg	2.1	#ifndef lint
2	greg	2.67	static const char RCSid[] = "$Id: aniso.c,v 2.66 2024/12/06 01:34:21 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	greg	2.61	#include "pmapmat.h"
18	greg	2.1
19	greg	2.32	#ifndef MAXITER
20			#define MAXITER 10 /* maximum # specular ray attempts */
21			#endif
22
23	greg	2.1	/*
24	greg	2.22	* This routine implements the anisotropic Gaussian
25	greg	2.54	* model described by Ward in Siggraph `92 article, updated with
26			* normalization and sampling adjustments due to Geisler-Moroder and Duer.
27	greg	2.1	* We orient the surface towards the incoming ray, so a single
28			* surface can be used to represent an infinitely thin object.
29			*
30			* Arguments for MAT_PLASTIC2 and MAT_METAL2 are:
31			* 4+ ux uy uz funcfile [transform...]
32			* 0
33	greg	2.54	* 6 red grn blu specular-frac. u-rough v-rough
34	greg	2.1	*
35			* Real arguments for MAT_TRANS2 are:
36			* 8 red grn blu rspec u-rough v-rough trans tspec
37			*/
38
39			/* specularity flags */
40			#define SP_REFL 01 /* has reflected specular component */
41			#define SP_TRAN 02 /* has transmitted specular */
42	greg	2.10	#define SP_FLAT 04 /* reflecting surface is flat */
43			#define SP_RBLT 010 /* reflection below sample threshold */
44			#define SP_TBLT 020 /* transmission below threshold */
45	greg	2.1
46			typedef struct {
47	greg	2.2	OBJREC mp; / material pointer */
48	greg	2.1	RAY rp; / ray pointer */
49			short specfl; /* specularity flags, defined above */
50	greg	2.62	SCOLOR mcolor; /* color of this material */
51			SCOLOR scolor; /* color of specular component */
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	greg	2.62	SCOLOR scval, /* 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	greg	2.62	SCOLOR sctmp;
81	greg	2.1
82	greg	2.62	scolorblack(scval);
83	greg	2.1
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	greg	2.62	copyscolor(sctmp, np->mcolor);
96	greg	2.42	dtmp = ldot * omega * np->rdiff * (1.0/PI);
97	greg	2.62	scalescolor(sctmp, dtmp);
98			saddscolor(scval, sctmp);
99	greg	2.1	}
100	greg	2.58
101			if ((ldot < -FTINY) & (np->tdiff > FTINY)) {
102			/*
103			* Compute diffuse transmission.
104			*/
105	greg	2.62	copyscolor(sctmp, np->mcolor);
106	greg	2.58	dtmp = -ldot * omega * np->tdiff * (1.0/PI);
107	greg	2.62	scalescolor(sctmp, dtmp);
108			saddscolor(scval, sctmp);
109	greg	2.58	}
110
111	greg	2.61	if (ambRayInPmap(np->rp))
112			return; /* specular accounted for in photon map */
113
114	greg	2.57	if (ldot > FTINY && np->specfl&SP_REFL) {
115	greg	2.1	/*
116			* Compute specular reflection coefficient using
117	greg	2.46	* anisotropic Gaussian distribution model.
118	greg	2.1	*/
119	greg	2.2	/* add source width if flat */
120			if (np->specfl & SP_FLAT)
121	greg	2.42	au2 = av2 = omega * (0.25/PI);
122	greg	2.2	else
123			au2 = av2 = 0.0;
124	greg	2.18	au2 += np->u_alpha*np->u_alpha;
125			av2 += np->v_alpha*np->v_alpha;
126	greg	2.1	/* half vector */
127	greg	2.54	VSUB(h, ldir, np->rp->rdir);
128	greg	2.1	/* ellipse */
129	greg	2.16	dtmp1 = DOT(np->u, h);
130			dtmp1 *= dtmp1 / au2;
131	greg	2.1	dtmp2 = DOT(np->v, h);
132			dtmp2 *= dtmp2 / av2;
133	greg	2.46	/* new W-G-M-D model */
134	greg	2.23	dtmp = DOT(np->pnorm, h);
135	greg	2.46	dtmp *= dtmp;
136			dtmp1 = (dtmp1 + dtmp2) / dtmp;
137			dtmp = exp(-dtmp1) * DOT(h,h) /
138			(PI * dtmpdtmp sqrt(au2*av2));
139	greg	2.1	/* worth using? */
140			if (dtmp > FTINY) {
141	greg	2.62	copyscolor(sctmp, np->scolor);
142	greg	2.46	dtmp = ldot omega;
143	greg	2.62	scalescolor(sctmp, dtmp);
144			saddscolor(scval, sctmp);
145	greg	2.1	}
146			}
147	greg	2.58
148	greg	2.57	if (ldot < -FTINY && np->specfl&SP_TRAN) {
149	greg	2.1	/*
150			* Compute specular transmission. Specular transmission
151			* is always modified by material color.
152			*/
153			/* roughness + source */
154	greg	2.42	au2 = av2 = omega * (1.0/PI);
155	greg	2.18	au2 += np->u_alpha*np->u_alpha;
156			av2 += np->v_alpha*np->v_alpha;
157	greg	2.16	/* "half vector" */
158	greg	2.54	VSUB(h, ldir, np->prdir);
159	greg	2.19	dtmp = DOT(h,h);
160	greg	2.16	if (dtmp > FTINY*FTINY) {
161	greg	2.19	dtmp1 = DOT(h,np->pnorm);
162			dtmp = 1.0 - dtmp1*dtmp1/dtmp;
163	greg	2.66	}
164			if (dtmp > FTINY*FTINY) {
165			dtmp1 = DOT(h,np->u);
166			dtmp1 *= dtmp1 / au2;
167			dtmp2 = DOT(h,np->v);
168			dtmp2 *= dtmp2 / av2;
169			dtmp = (dtmp1 + dtmp2) / dtmp;
170			dtmp = exp(-dtmp);
171	greg	2.16	} else
172	greg	2.66	dtmp = 1.0;
173	greg	2.46	/* Gaussian */
174	greg	2.66	dtmp = (1.0/PI) sqrt(-ldot/(np->pdotau2av2));
175	greg	2.1	/* worth using? */
176			if (dtmp > FTINY) {
177	greg	2.62	copyscolor(sctmp, np->mcolor);
178	greg	2.16	dtmp = np->tspec omega;
179	greg	2.62	scalescolor(sctmp, dtmp);
180			saddscolor(scval, sctmp);
181	greg	2.1	}
182			}
183			}
184
185
186	greg	2.54	int
187	schorsch	2.41	m_aniso( /* shade ray that hit something anisotropic */
188	greg	2.54	OBJREC *m,
189			RAY *r
190	schorsch	2.41	)
191	greg	2.1	{
192			ANISODAT nd;
193	greg	2.62	SCOLOR sctmp;
194	greg	2.54	int i;
195	greg	2.1	/* easy shadow test */
196	greg	2.10	if (r->crtype & SHADOW)
197	greg	2.27	return(1);
198	greg	2.1
199			if (m->oargs.nfargs != (m->otype == MAT_TRANS2 ? 8 : 6))
200			objerror(m, USER, "bad number of real arguments");
201	greg	2.36	/* check for back side */
202			if (r->rod < 0.0) {
203	greg	2.56	if (!backvis) {
204	greg	2.36	raytrans(r);
205			return(1);
206			}
207			raytexture(r, m->omod);
208			flipsurface(r); /* reorient if backvis */
209			} else
210			raytexture(r, m->omod);
211			/* get material color */
212	greg	2.2	nd.mp = m;
213	greg	2.1	nd.rp = r;
214	greg	2.62	setscolor(nd.mcolor, m->oargs.farg[0],
215	greg	2.1	m->oargs.farg[1],
216			m->oargs.farg[2]);
217			/* get roughness */
218			nd.specfl = 0;
219	greg	2.18	nd.u_alpha = m->oargs.farg[4];
220			nd.v_alpha = m->oargs.farg[5];
221	greg	2.54	if ((nd.u_alpha <= FTINY) \| (nd.v_alpha <= FTINY))
222	greg	2.10	objerror(m, USER, "roughness too small");
223	greg	2.36
224	greg	2.1	nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */
225			if (nd.pdot < .001)
226			nd.pdot = .001; /* non-zero for diraniso() */
227	greg	2.62	smultscolor(nd.mcolor, r->pcol); /* modify material color */
228	greg	2.1	/* get specular component */
229			if ((nd.rspec = m->oargs.farg[3]) > FTINY) {
230			nd.specfl \|= SP_REFL;
231			/* compute specular color */
232			if (m->otype == MAT_METAL2)
233	greg	2.62	copyscolor(nd.scolor, nd.mcolor);
234	greg	2.1	else
235	greg	2.62	setscolor(nd.scolor, 1.0, 1.0, 1.0);
236			scalescolor(nd.scolor, nd.rspec);
237	greg	2.4	/* check threshold */
238	greg	2.25	if (specthresh >= nd.rspec-FTINY)
239	greg	2.4	nd.specfl \|= SP_RBLT;
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	2.67	if (r->ro != NULL && isflat(r->ro->otype) &&
269			DOT(r->pert,r->pert) <= FTINY*FTINY)
270	greg	2.4	nd.specfl \|= SP_FLAT;
271
272	greg	2.55	getacoords(&nd); /* set up coordinates */
273	greg	2.1
274	greg	2.60	if (nd.specfl & (SP_REFL\|SP_TRAN))
275	greg	2.55	agaussamp(&nd);
276	greg	2.1
277			if (nd.rdiff > FTINY) { /* ambient from this side */
278	greg	2.62	copyscolor(sctmp, nd.mcolor); /* modified by material color */
279			scalescolor(sctmp, nd.rdiff);
280	greg	2.52	if (nd.specfl & SP_RBLT) /* add in specular as well? */
281	greg	2.62	saddscolor(sctmp, nd.scolor);
282			multambient(sctmp, r, nd.pnorm);
283			saddscolor(r->rcol, sctmp); /* add to returned color */
284	greg	2.1	}
285	greg	2.58
286	greg	2.1	if (nd.tdiff > FTINY) { /* ambient from other side */
287	greg	2.31	FVECT bnorm;
288			bnorm[0] = -nd.pnorm[0];
289			bnorm[1] = -nd.pnorm[1];
290			bnorm[2] = -nd.pnorm[2];
291	greg	2.62	copyscolor(sctmp, nd.mcolor); /* modified by color */
292			if (nd.specfl & SP_TBLT) {
293			scalescolor(sctmp, nd.trans);
294			} else {
295			scalescolor(sctmp, nd.tdiff);
296			}
297			multambient(sctmp, r, bnorm);
298			saddscolor(r->rcol, sctmp);
299	greg	2.1	}
300			/* add direct component */
301			direct(r, diraniso, &nd);
302	greg	2.27
303			return(1);
304	greg	2.1	}
305
306	greg	2.34	static void
307	schorsch	2.41	getacoords( /* set up coordinate system */
308	greg	2.54	ANISODAT *np
309	schorsch	2.41	)
310	greg	2.1	{
311	greg	2.54	MFUNC *mf;
312			int i;
313	greg	2.1
314			mf = getfunc(np->mp, 3, 0x7, 1);
315	greg	2.55	setfunc(np->mp, np->rp);
316	greg	2.1	errno = 0;
317			for (i = 0; i < 3; i++)
318			np->u[i] = evalue(mf->ep[i]);
319	greg	2.57	if ((errno == EDOM) \| (errno == ERANGE))
320			np->u[0] = np->u[1] = np->u[2] = 0.0;
321	greg	2.65	else if (mf->fxp != &unitxf)
322	greg	2.53	multv3(np->u, np->u, mf->fxp->xfm);
323	greg	2.1	fcross(np->v, np->pnorm, np->u);
324			if (normalize(np->v) == 0.0) {
325	greg	2.57	if (fabs(np->u_alpha - np->v_alpha) > 0.001)
326			objerror(np->mp, WARNING, "illegal orientation vector");
327	greg	2.59	getperpendicular(np->u, np->pnorm, 1); /* punting */
328	greg	2.57	fcross(np->v, np->pnorm, np->u);
329			np->u_alpha = np->v_alpha = sqrt( 0.5 *
330			(np->u_alphanp->u_alpha + np->v_alphanp->v_alpha) );
331			} else
332			fcross(np->u, np->v, np->pnorm);
333	greg	2.1	}
334
335
336	greg	2.34	static void
337	greg	2.46	agaussamp( /* sample anisotropic Gaussian specular */
338	greg	2.54	ANISODAT *np
339	schorsch	2.41	)
340	greg	2.1	{
341			RAY sr;
342			FVECT h;
343			double rv[2];
344			double d, sinp, cosp;
345	greg	2.50	int maxiter, ntrials, nstarget, nstaken;
346	greg	2.54	int i;
347	greg	2.1	/* compute reflection */
348	greg	2.4	if ((np->specfl & (SP_REFL\|SP_RBLT)) == SP_REFL &&
349	greg	2.64	rayorigin(&sr, RSPECULAR, np->rp, np->scolor) == 0) {
350	greg	2.65	SCOLOR scol;
351	greg	2.50	nstarget = 1;
352	greg	2.47	if (specjitter > 1.5) { /* multiple samples? */
353	greg	2.55	nstarget = specjitter*np->rp->rweight + .5;
354	greg	2.50	if (sr.rweight <= minweight*nstarget)
355			nstarget = sr.rweight/minweight;
356			if (nstarget > 1) {
357			d = 1./nstarget;
358	greg	2.63	scalescolor(sr.rcoef, d);
359	greg	2.48	sr.rweight *= d;
360	greg	2.47	} else
361	greg	2.50	nstarget = 1;
362	greg	2.47	}
363	greg	2.62	scolorblack(scol);
364	greg	2.51	dimlist[ndims++] = (int)(size_t)np->mp;
365	greg	2.50	maxiter = MAXITER*nstarget;
366	greg	2.65	for (nstaken = ntrials = 0; (nstaken < nstarget) &
367			(ntrials < maxiter); ntrials++) {
368	greg	2.50	if (ntrials)
369	greg	2.32	d = frandom();
370			else
371			d = urand(ilhash(dimlist,ndims)+samplendx);
372			multisamp(rv, 2, d);
373			d = 2.0PI rv[0];
374	gwlarson	2.33	cosp = tcos(d) * np->u_alpha;
375			sinp = tsin(d) * np->v_alpha;
376	greg	2.47	d = 1./sqrt(cospcosp + sinpsinp);
377			cosp *= d;
378			sinp *= d;
379			if ((0. <= specjitter) & (specjitter < 1.))
380			rv[1] = 1.0 - specjitter*rv[1];
381	greg	2.65	d = (rv[1] <= FTINY) ? 1.0 : sqrt( -log(rv[1]) /
382	greg	2.32	(cospcosp/(np->u_alphanp->u_alpha) +
383	greg	2.65	sinpsinp/(np->v_alphanp->v_alpha)) );
384	greg	2.32	for (i = 0; i < 3; i++)
385			h[i] = np->pnorm[i] +
386			d(cospnp->u[i] + sinp*np->v[i]);
387	greg	2.55	d = -2.0 * DOT(h, np->rp->rdir) / (1.0 + d*d);
388			VSUM(sr.rdir, np->rp->rdir, h, d);
389	greg	2.50	/* sample rejection test */
390	greg	2.55	if ((d = DOT(sr.rdir, np->rp->ron)) <= FTINY)
391	greg	2.47	continue;
392			checknorm(sr.rdir);
393	greg	2.50	if (nstarget > 1) { /* W-G-M-D adjustment */
394			if (nstaken) rayclear(&sr);
395			rayvalue(&sr);
396	greg	2.55	d = 2./(1. + np->rp->rod/d);
397	greg	2.62	scalescolor(sr.rcol, d);
398			saddscolor(scol, sr.rcol);
399	greg	2.50	} else {
400			rayvalue(&sr);
401	greg	2.62	smultscolor(sr.rcol, sr.rcoef);
402			saddscolor(np->rp->rcol, sr.rcol);
403	greg	2.32	}
404	greg	2.50	++nstaken;
405			}
406			if (nstarget > 1) { /* final W-G-M-D weighting */
407	greg	2.62	smultscolor(scol, sr.rcoef);
408	greg	2.50	d = (double)nstarget/ntrials;
409	greg	2.62	scalescolor(scol, d);
410			saddscolor(np->rp->rcol, scol);
411	greg	2.32	}
412	greg	2.1	ndims--;
413			}
414			/* compute transmission */
415	greg	2.62	copyscolor(sr.rcoef, np->mcolor); /* modify by material color */
416			scalescolor(sr.rcoef, np->tspec);
417	greg	2.7	if ((np->specfl & (SP_TRAN\|SP_TBLT)) == SP_TRAN &&
418	greg	2.64	rayorigin(&sr, TSPECULAR, np->rp, sr.rcoef) == 0) {
419	greg	2.50	nstarget = 1;
420	greg	2.47	if (specjitter > 1.5) { /* multiple samples? */
421	greg	2.55	nstarget = specjitter*np->rp->rweight + .5;
422	greg	2.50	if (sr.rweight <= minweight*nstarget)
423			nstarget = sr.rweight/minweight;
424			if (nstarget > 1) {
425			d = 1./nstarget;
426	greg	2.63	scalescolor(sr.rcoef, d);
427	greg	2.48	sr.rweight *= d;
428	greg	2.47	} else
429	greg	2.50	nstarget = 1;
430	greg	2.47	}
431	greg	2.51	dimlist[ndims++] = (int)(size_t)np->mp;
432	greg	2.50	maxiter = MAXITER*nstarget;
433	greg	2.65	for (nstaken = ntrials = 0; (nstaken < nstarget) &
434			(ntrials < maxiter); ntrials++) {
435	greg	2.50	if (ntrials)
436	greg	2.32	d = frandom();
437			else
438			d = urand(ilhash(dimlist,ndims)+1823+samplendx);
439			multisamp(rv, 2, d);
440			d = 2.0PI rv[0];
441	gwlarson	2.33	cosp = tcos(d) * np->u_alpha;
442			sinp = tsin(d) * np->v_alpha;
443	greg	2.47	d = 1./sqrt(cospcosp + sinpsinp);
444			cosp *= d;
445			sinp *= d;
446			if ((0. <= specjitter) & (specjitter < 1.))
447			rv[1] = 1.0 - specjitter*rv[1];
448	greg	2.32	if (rv[1] <= FTINY)
449			d = 1.0;
450			else
451			d = sqrt(-log(rv[1]) /
452			(cospcosp/(np->u_alphanp->u_alpha) +
453	gwlarson	2.33	sinpsinp/(np->v_alphanp->v_alpha)));
454	greg	2.32	for (i = 0; i < 3; i++)
455			sr.rdir[i] = np->prdir[i] +
456			d(cospnp->u[i] + sinp*np->v[i]);
457	greg	2.65	if (DOT(sr.rdir,np->rp->ron) >= -FTINY)
458			continue; /* reject sample */
459	greg	2.47	normalize(sr.rdir); /* OK, normalize */
460	greg	2.50	if (nstaken) /* multi-sampling */
461	greg	2.47	rayclear(&sr);
462			rayvalue(&sr);
463	greg	2.62	smultscolor(sr.rcol, sr.rcoef);
464			saddscolor(np->rp->rcol, sr.rcol);
465	greg	2.50	++nstaken;
466	greg	2.32	}
467	greg	2.7	ndims--;
468			}
469	greg	2.1	}