src/rt/aniso.c

/* Copyright (c) 1992 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 *  Shading functions for anisotropic materials.
 */

#include  "ray.h"

#include  "otypes.h"

#include  "func.h"

#include  "random.h"

extern double  specthresh;              /* specular sampling threshold */
extern double  specjitter;              /* specular sampling jitter */

static  agaussamp();

/*
 *      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 */


diraniso(cval, np, ldir, omega)         /* compute source contribution */
COLOR  cval;                    /* returned coefficient */
register ANISODAT  *np;         /* material data */
FVECT  ldir;                    /* light source direction */
double  omega;                  /* light source size */
{
        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 / 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/(4.0*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;
                                                /* gaussian */
                dtmp = DOT(np->pnorm, h);
                dtmp = (dtmp1 + dtmp2) / (dtmp*dtmp);
                dtmp = exp(-dtmp) * (0.25/PI)
                                * sqrt(ldot/(np->pdot*au2*av2));
                                                /* worth using? */
                if (dtmp > FTINY) {
                        copycolor(ctmp, np->scolor);
                        dtmp *= 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 / 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 / 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);
                }
        }
}


m_aniso(m, r)                   /* 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;

        if (m->oargs.nfargs != (m->otype == MAT_TRANS2 ? 8 : 6))
                objerror(m, USER, "bad number of real arguments");
        nd.mp = m;
        nd.rp = r;
                                                /* get material color */
        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");
                                                /* reorient if necessary */
        if (r->rod < 0.0)
                flipsurface(r);
                                                /* get modifiers */
        raytexture(r, m->omod);
        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 */
                for (i = 0; i < 3; i++)
                        nd.vrefl[i] = r->rdir[i] + 2.0*nd.pdot*nd.pnorm[i];
                if (DOT(nd.vrefl, r->ron) <= FTINY)     /* penetration? */
                        for (i = 0; i < 3; i++)         /* safety measure */
                                nd.vrefl[i] = r->rdir[i] + 2.*r->rod*r->ron[i];
        }
                                                /* 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 && (r->ro->otype == OBJ_FACE ||
                        r->ro->otype == OBJ_RING))
                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 */
                ambient(ctmp, r);
                if (nd.specfl & SP_RBLT)
                        scalecolor(ctmp, 1.0-nd.trans);
                else
                        scalecolor(ctmp, nd.rdiff);
                multcolor(ctmp, nd.mcolor);     /* modified by material color */
                addcolor(r->rcol, ctmp);        /* add to returned color */
        }
        if (nd.tdiff > FTINY) {         /* ambient from other side */
                flipsurface(r);
                ambient(ctmp, r);
                if (nd.specfl & SP_TBLT)
                        scalecolor(ctmp, nd.trans);
                else
                        scalecolor(ctmp, nd.tdiff);
                multcolor(ctmp, nd.mcolor);     /* modified by color */
                addcolor(r->rcol, ctmp);
                flipsurface(r);
        }
                                        /* add direct component */
        direct(r, diraniso, &nd);
}


static
getacoords(r, np)               /* 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) {
                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
agaussamp(r, np)                /* sample anisotropic gaussian specular */
RAY  *r;
register ANISODAT  *np;
{
        RAY  sr;
        FVECT  h;
        double  rv[2];
        double  d, sinp, cosp;
        register int  i;
                                        /* compute reflection */
        if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL &&
                        rayorigin(&sr, r, SPECULAR, np->rspec) == 0) {
                dimlist[ndims++] = (int)np->mp;
                d = urand(ilhash(dimlist,ndims)+samplendx);
                multisamp(rv, 2, d);
                d = 2.0*PI * rv[0];
                cosp = cos(d) * np->u_alpha;
                sinp = sin(d) * np->v_alpha;
                d = sqrt(cosp*cosp + sinp*sinp);
                cosp /= d;
                sinp /= d;
                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);
                for (i = 0; i < 3; i++)
                        sr.rdir[i] = r->rdir[i] + d*h[i];
                if (DOT(sr.rdir, r->ron) <= FTINY)      /* penetration? */
                        VCOPY(sr.rdir, np->vrefl);      /* jitter no good */
                rayvalue(&sr);
                multcolor(sr.rcol, np->scolor);
                addcolor(r->rcol, sr.rcol);
                ndims--;
        }
                                        /* compute transmission */
        if ((np->specfl & (SP_TRAN|SP_TBLT)) == SP_TRAN &&
                        rayorigin(&sr, r, SPECULAR, np->tspec) == 0) {
                dimlist[ndims++] = (int)np->mp;
                d = urand(ilhash(dimlist,ndims)+1823+samplendx);
                multisamp(rv, 2, d);
                d = 2.0*PI * rv[0];
                cosp = cos(d) * np->u_alpha;
                sinp = sin(d) * np->v_alpha;
                d = sqrt(cosp*cosp + sinp*sinp);
                cosp /= d;
                sinp /= d;
                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->u_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)
                        normalize(sr.rdir);             /* OK, normalize */
                else
                        VCOPY(sr.rdir, np->prdir);      /* else no jitter */
                rayvalue(&sr);
                scalecolor(sr.rcol, np->tspec);
                multcolor(sr.rcol, np->mcolor);         /* modify by color */
                addcolor(r->rcol, sr.rcol);
                ndims--;
        }
}
Revision:	2.25
Committed:	Thu May 27 15:27:57 1993 UTC (30 years, 11 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.24:	+2 -14 lines
Log Message:	removed approximation to Fresnel reflection, since the direct component was not being calculated accordingly (BRDF not bidirectional) changed BRDTfunc arguments and operation, fixed one or two bugs there also
#	User	Rev	Content
1	greg	2.1	/* Copyright (c) 1992 Regents of the University of California */
2
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* Shading functions for anisotropic materials.
9			*/
10
11			#include "ray.h"
12
13			#include "otypes.h"
14
15			#include "func.h"
16
17			#include "random.h"
18
19	greg	2.4	extern double specthresh; /* specular sampling threshold */
20			extern double specjitter; /* specular sampling jitter */
21
22	greg	2.24	static agaussamp();
23
24	greg	2.1	/*
25	greg	2.22	* This routine implements the anisotropic Gaussian
26			* model described by Ward in Siggraph `92 article.
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			* 6 red grn blu specular-frac. u-facet-slope v-facet-slope
34			*
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			#define SP_BADU 040 /* bad u direction calculation */
46	greg	2.1
47			typedef struct {
48	greg	2.2	OBJREC mp; / material pointer */
49	greg	2.1	RAY rp; / ray pointer */
50			short specfl; /* specularity flags, defined above */
51			COLOR mcolor; /* color of this material */
52			COLOR scolor; /* color of specular component */
53	greg	2.6	FVECT vrefl; /* vector in reflected direction */
54	greg	2.1	FVECT prdir; /* vector in transmitted direction */
55			FVECT u, v; /* u and v vectors orienting anisotropy */
56	greg	2.18	double u_alpha; /* u roughness */
57			double v_alpha; /* v roughness */
58	greg	2.1	double rdiff, rspec; /* reflected specular, diffuse */
59			double trans; /* transmissivity */
60			double tdiff, tspec; /* transmitted specular, diffuse */
61			FVECT pnorm; /* perturbed surface normal */
62			double pdot; /* perturbed dot product */
63			} ANISODAT; /* anisotropic material data */
64
65
66			diraniso(cval, np, ldir, omega) /* compute source contribution */
67			COLOR cval; /* returned coefficient */
68			register ANISODAT np; / material data */
69			FVECT ldir; /* light source direction */
70			double omega; /* light source size */
71			{
72			double ldot;
73	greg	2.16	double dtmp, dtmp1, dtmp2;
74	greg	2.1	FVECT h;
75			double au2, av2;
76			COLOR ctmp;
77
78			setcolor(cval, 0.0, 0.0, 0.0);
79
80			ldot = DOT(np->pnorm, ldir);
81
82			if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY)
83			return; /* wrong side */
84
85			if (ldot > FTINY && np->rdiff > FTINY) {
86			/*
87			* Compute and add diffuse reflected component to returned
88			* color. The diffuse reflected component will always be
89			* modified by the color of the material.
90			*/
91			copycolor(ctmp, np->mcolor);
92			dtmp = ldot * omega * np->rdiff / PI;
93			scalecolor(ctmp, dtmp);
94			addcolor(cval, ctmp);
95			}
96	greg	2.10	if (ldot > FTINY && (np->specfl&(SP_REFL\|SP_BADU)) == SP_REFL) {
97	greg	2.1	/*
98			* Compute specular reflection coefficient using
99			* anisotropic gaussian distribution model.
100			*/
101	greg	2.2	/* add source width if flat */
102			if (np->specfl & SP_FLAT)
103			au2 = av2 = omega/(4.0*PI);
104			else
105			au2 = av2 = 0.0;
106	greg	2.18	au2 += np->u_alpha*np->u_alpha;
107			av2 += np->v_alpha*np->v_alpha;
108	greg	2.1	/* half vector */
109			h[0] = ldir[0] - np->rp->rdir[0];
110			h[1] = ldir[1] - np->rp->rdir[1];
111			h[2] = ldir[2] - np->rp->rdir[2];
112			/* ellipse */
113	greg	2.16	dtmp1 = DOT(np->u, h);
114			dtmp1 *= dtmp1 / au2;
115	greg	2.1	dtmp2 = DOT(np->v, h);
116			dtmp2 *= dtmp2 / av2;
117			/* gaussian */
118	greg	2.23	dtmp = DOT(np->pnorm, h);
119			dtmp = (dtmp1 + dtmp2) / (dtmp*dtmp);
120			dtmp = exp(-dtmp) * (0.25/PI)
121	greg	2.16	* sqrt(ldot/(np->pdotau2av2));
122	greg	2.1	/* worth using? */
123			if (dtmp > FTINY) {
124			copycolor(ctmp, np->scolor);
125	greg	2.16	dtmp *= omega;
126	greg	2.1	scalecolor(ctmp, dtmp);
127			addcolor(cval, ctmp);
128			}
129			}
130			if (ldot < -FTINY && np->tdiff > FTINY) {
131			/*
132			* Compute diffuse transmission.
133			*/
134			copycolor(ctmp, np->mcolor);
135			dtmp = -ldot * omega * np->tdiff / PI;
136			scalecolor(ctmp, dtmp);
137			addcolor(cval, ctmp);
138			}
139	greg	2.10	if (ldot < -FTINY && (np->specfl&(SP_TRAN\|SP_BADU)) == SP_TRAN) {
140	greg	2.1	/*
141			* Compute specular transmission. Specular transmission
142			* is always modified by material color.
143			*/
144			/* roughness + source */
145	greg	2.16	au2 = av2 = omega / PI;
146	greg	2.18	au2 += np->u_alpha*np->u_alpha;
147			av2 += np->v_alpha*np->v_alpha;
148	greg	2.16	/* "half vector" */
149			h[0] = ldir[0] - np->prdir[0];
150			h[1] = ldir[1] - np->prdir[1];
151			h[2] = ldir[2] - np->prdir[2];
152	greg	2.19	dtmp = DOT(h,h);
153	greg	2.16	if (dtmp > FTINY*FTINY) {
154	greg	2.19	dtmp1 = DOT(h,np->pnorm);
155			dtmp = 1.0 - dtmp1*dtmp1/dtmp;
156			if (dtmp > FTINY*FTINY) {
157			dtmp1 = DOT(h,np->u);
158	greg	2.23	dtmp1 *= dtmp1 / au2;
159	greg	2.19	dtmp2 = DOT(h,np->v);
160	greg	2.23	dtmp2 *= dtmp2 / av2;
161	greg	2.19	dtmp = (dtmp1 + dtmp2) / dtmp;
162			}
163	greg	2.16	} else
164			dtmp = 0.0;
165	greg	2.1	/* gaussian */
166	greg	2.21	dtmp = exp(-dtmp) * (1.0/PI)
167	greg	2.16	* sqrt(-ldot/(np->pdotau2av2));
168	greg	2.1	/* worth using? */
169			if (dtmp > FTINY) {
170			copycolor(ctmp, np->mcolor);
171	greg	2.16	dtmp = np->tspec omega;
172	greg	2.1	scalecolor(ctmp, dtmp);
173			addcolor(cval, ctmp);
174			}
175			}
176			}
177
178
179			m_aniso(m, r) /* shade ray that hit something anisotropic */
180			register OBJREC *m;
181			register RAY *r;
182			{
183			ANISODAT nd;
184			COLOR ctmp;
185			register int i;
186			/* easy shadow test */
187	greg	2.10	if (r->crtype & SHADOW)
188	greg	2.1	return;
189
190			if (m->oargs.nfargs != (m->otype == MAT_TRANS2 ? 8 : 6))
191			objerror(m, USER, "bad number of real arguments");
192	greg	2.2	nd.mp = m;
193	greg	2.1	nd.rp = r;
194			/* get material color */
195			setcolor(nd.mcolor, m->oargs.farg[0],
196			m->oargs.farg[1],
197			m->oargs.farg[2]);
198			/* get roughness */
199			nd.specfl = 0;
200	greg	2.18	nd.u_alpha = m->oargs.farg[4];
201			nd.v_alpha = m->oargs.farg[5];
202			if (nd.u_alpha < FTINY \|\| nd.v_alpha <= FTINY)
203	greg	2.10	objerror(m, USER, "roughness too small");
204	greg	2.1	/* reorient if necessary */
205			if (r->rod < 0.0)
206			flipsurface(r);
207			/* get modifiers */
208			raytexture(r, m->omod);
209			nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */
210			if (nd.pdot < .001)
211			nd.pdot = .001; /* non-zero for diraniso() */
212			multcolor(nd.mcolor, r->pcol); /* modify material color */
213			/* get specular component */
214			if ((nd.rspec = m->oargs.farg[3]) > FTINY) {
215			nd.specfl \|= SP_REFL;
216			/* compute specular color */
217			if (m->otype == MAT_METAL2)
218			copycolor(nd.scolor, nd.mcolor);
219			else
220			setcolor(nd.scolor, 1.0, 1.0, 1.0);
221			scalecolor(nd.scolor, nd.rspec);
222	greg	2.4	/* check threshold */
223	greg	2.25	if (specthresh >= nd.rspec-FTINY)
224	greg	2.4	nd.specfl \|= SP_RBLT;
225	greg	2.6	/* compute refl. direction */
226			for (i = 0; i < 3; i++)
227			nd.vrefl[i] = r->rdir[i] + 2.0nd.pdotnd.pnorm[i];
228			if (DOT(nd.vrefl, r->ron) <= FTINY) /* penetration? */
229			for (i = 0; i < 3; i++) /* safety measure */
230			nd.vrefl[i] = r->rdir[i] + 2.r->rodr->ron[i];
231	greg	2.1	}
232			/* compute transmission */
233	greg	2.16	if (m->otype == MAT_TRANS2) {
234	greg	2.1	nd.trans = m->oargs.farg[6]*(1.0 - nd.rspec);
235			nd.tspec = nd.trans * m->oargs.farg[7];
236			nd.tdiff = nd.trans - nd.tspec;
237			if (nd.tspec > FTINY) {
238			nd.specfl \|= SP_TRAN;
239	greg	2.4	/* check threshold */
240	greg	2.25	if (specthresh >= nd.tspec-FTINY)
241	greg	2.4	nd.specfl \|= SP_TBLT;
242	greg	2.10	if (DOT(r->pert,r->pert) <= FTINY*FTINY) {
243	greg	2.1	VCOPY(nd.prdir, r->rdir);
244			} else {
245			for (i = 0; i < 3; i++) /* perturb */
246	greg	2.17	nd.prdir[i] = r->rdir[i] - r->pert[i];
247	greg	2.6	if (DOT(nd.prdir, r->ron) < -FTINY)
248			normalize(nd.prdir); /* OK */
249			else
250			VCOPY(nd.prdir, r->rdir);
251	greg	2.1	}
252			}
253			} else
254			nd.tdiff = nd.tspec = nd.trans = 0.0;
255
256			/* diffuse reflection */
257			nd.rdiff = 1.0 - nd.trans - nd.rspec;
258
259	greg	2.11	if (r->ro != NULL && (r->ro->otype == OBJ_FACE \|\|
260			r->ro->otype == OBJ_RING))
261	greg	2.4	nd.specfl \|= SP_FLAT;
262
263	greg	2.1	getacoords(r, &nd); /* set up coordinates */
264
265	greg	2.10	if (nd.specfl & (SP_REFL\|SP_TRAN) && !(nd.specfl & SP_BADU))
266	greg	2.1	agaussamp(r, &nd);
267
268			if (nd.rdiff > FTINY) { /* ambient from this side */
269			ambient(ctmp, r);
270	greg	2.4	if (nd.specfl & SP_RBLT)
271			scalecolor(ctmp, 1.0-nd.trans);
272			else
273			scalecolor(ctmp, nd.rdiff);
274	greg	2.1	multcolor(ctmp, nd.mcolor); /* modified by material color */
275			addcolor(r->rcol, ctmp); /* add to returned color */
276			}
277			if (nd.tdiff > FTINY) { /* ambient from other side */
278			flipsurface(r);
279			ambient(ctmp, r);
280	greg	2.4	if (nd.specfl & SP_TBLT)
281			scalecolor(ctmp, nd.trans);
282			else
283			scalecolor(ctmp, nd.tdiff);
284	greg	2.1	multcolor(ctmp, nd.mcolor); /* modified by color */
285			addcolor(r->rcol, ctmp);
286			flipsurface(r);
287			}
288			/* add direct component */
289			direct(r, diraniso, &nd);
290			}
291
292
293			static
294			getacoords(r, np) /* set up coordinate system */
295			RAY *r;
296			register ANISODAT *np;
297			{
298			register MFUNC *mf;
299			register int i;
300
301			mf = getfunc(np->mp, 3, 0x7, 1);
302			setfunc(np->mp, r);
303			errno = 0;
304			for (i = 0; i < 3; i++)
305			np->u[i] = evalue(mf->ep[i]);
306			if (errno) {
307			objerror(np->mp, WARNING, "compute error");
308			np->specfl \|= SP_BADU;
309			return;
310			}
311	greg	2.16	if (mf->f != &unitxf)
312			multv3(np->u, np->u, mf->f->xfm);
313	greg	2.1	fcross(np->v, np->pnorm, np->u);
314			if (normalize(np->v) == 0.0) {
315			objerror(np->mp, WARNING, "illegal orientation vector");
316			np->specfl \|= SP_BADU;
317			return;
318			}
319			fcross(np->u, np->v, np->pnorm);
320			}
321
322
323			static
324			agaussamp(r, np) /* sample anisotropic gaussian specular */
325			RAY *r;
326			register ANISODAT *np;
327			{
328			RAY sr;
329			FVECT h;
330			double rv[2];
331			double d, sinp, cosp;
332			register int i;
333			/* compute reflection */
334	greg	2.4	if ((np->specfl & (SP_REFL\|SP_RBLT)) == SP_REFL &&
335	greg	2.1	rayorigin(&sr, r, SPECULAR, np->rspec) == 0) {
336			dimlist[ndims++] = (int)np->mp;
337	greg	2.6	d = urand(ilhash(dimlist,ndims)+samplendx);
338			multisamp(rv, 2, d);
339			d = 2.0PI rv[0];
340	greg	2.18	cosp = cos(d) * np->u_alpha;
341			sinp = sin(d) * np->v_alpha;
342			d = sqrt(cospcosp + sinpsinp);
343	greg	2.6	cosp /= d;
344			sinp /= d;
345			rv[1] = 1.0 - specjitter*rv[1];
346			if (rv[1] <= FTINY)
347			d = 1.0;
348			else
349			d = sqrt(-log(rv[1]) /
350	greg	2.18	(cospcosp/(np->u_alphanp->u_alpha) +
351			sinpsinp/(np->v_alphanp->v_alpha)));
352	greg	2.6	for (i = 0; i < 3; i++)
353			h[i] = np->pnorm[i] +
354			d(cospnp->u[i] + sinp*np->v[i]);
355			d = -2.0 * DOT(h, r->rdir) / (1.0 + d*d);
356			for (i = 0; i < 3; i++)
357			sr.rdir[i] = r->rdir[i] + d*h[i];
358			if (DOT(sr.rdir, r->ron) <= FTINY) /* penetration? */
359			VCOPY(sr.rdir, np->vrefl); /* jitter no good */
360			rayvalue(&sr);
361			multcolor(sr.rcol, np->scolor);
362			addcolor(r->rcol, sr.rcol);
363	greg	2.1	ndims--;
364			}
365			/* compute transmission */
366	greg	2.7	if ((np->specfl & (SP_TRAN\|SP_TBLT)) == SP_TRAN &&
367			rayorigin(&sr, r, SPECULAR, np->tspec) == 0) {
368			dimlist[ndims++] = (int)np->mp;
369			d = urand(ilhash(dimlist,ndims)+1823+samplendx);
370			multisamp(rv, 2, d);
371			d = 2.0PI rv[0];
372	greg	2.18	cosp = cos(d) * np->u_alpha;
373			sinp = sin(d) * np->v_alpha;
374			d = sqrt(cospcosp + sinpsinp);
375			cosp /= d;
376			sinp /= d;
377	greg	2.7	rv[1] = 1.0 - specjitter*rv[1];
378			if (rv[1] <= FTINY)
379			d = 1.0;
380			else
381			d = sqrt(-log(rv[1]) /
382	greg	2.18	(cospcosp/(np->u_alphanp->u_alpha) +
383			sinpsinp/(np->v_alphanp->u_alpha)));
384	greg	2.7	for (i = 0; i < 3; i++)
385			sr.rdir[i] = np->prdir[i] +
386			d(cospnp->u[i] + sinp*np->v[i]);
387			if (DOT(sr.rdir, r->ron) < -FTINY)
388			normalize(sr.rdir); /* OK, normalize */
389			else
390			VCOPY(sr.rdir, np->prdir); /* else no jitter */
391			rayvalue(&sr);
392	greg	2.10	scalecolor(sr.rcol, np->tspec);
393			multcolor(sr.rcol, np->mcolor); /* modify by color */
394	greg	2.7	addcolor(r->rcol, sr.rcol);
395			ndims--;
396			}
397	greg	2.1	}