src/rt/normal.c

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

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

/*
 *  normal.c - shading function for normal materials.
 *
 *     8/19/85
 *     12/19/85 - added stuff for metals.
 *     6/26/87 - improved specular model.
 *     9/28/87 - added model for translucent materials.
 *     Later changes described in delta comments.
 */

#include  "ray.h"

#include  "otypes.h"

#include  "random.h"

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

static  gaussamp();

/*
 *      This routine implements the isotropic 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_PLASTIC and MAT_METAL are:
 *      red     grn     blu     specular-frac.  facet-slope
 *
 *  Arguments for MAT_TRANS are:
 *      red     grn     blu     rspec   rough   trans   tspec
 */

                                /* specularity flags */
#define  SP_REFL        01              /* has reflected specular component */
#define  SP_TRAN        02              /* has transmitted specular */
#define  SP_PURE        04              /* purely specular (zero roughness) */
#define  SP_FLAT        010             /* flat reflecting surface */
#define  SP_RBLT        020             /* reflection below sample threshold */
#define  SP_TBLT        040             /* 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 direction of reflected ray */
        FVECT  prdir;           /* vector in transmitted direction */
        double  alpha2;         /* roughness squared */
        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 */
}  NORMDAT;             /* normal material data */


dirnorm(cval, np, ldir, omega)          /* compute source contribution */
COLOR  cval;                    /* returned coefficient */
register NORMDAT  *np;          /* material data */
FVECT  ldir;                    /* light source direction */
double  omega;                  /* light source size */
{
        double  ldot;
        double  dtmp, d2;
        FVECT  vtmp;
        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_PURE)) == SP_REFL) {
                /*
                 *  Compute specular reflection coefficient using
                 *  gaussian distribution model.
                 */
                                                /* roughness */
                dtmp = np->alpha2;
                                                /* + source if flat */
                if (np->specfl & SP_FLAT)
                        dtmp += omega/(4.0*PI);
                                                /* half vector */
                vtmp[0] = ldir[0] - np->rp->rdir[0];
                vtmp[1] = ldir[1] - np->rp->rdir[1];
                vtmp[2] = ldir[2] - np->rp->rdir[2];
                d2 = DOT(vtmp, np->pnorm);
                d2 *= d2;
                d2 = (DOT(vtmp,vtmp) - d2) / d2;
                                                /* gaussian */
                dtmp = exp(-d2/dtmp)/(4.*PI*dtmp);
                                                /* worth using? */
                if (dtmp > FTINY) {
                        copycolor(ctmp, np->scolor);
                        dtmp *= omega * sqrt(ldot/np->pdot);
                        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_PURE)) == SP_TRAN) {
                /*
                 *  Compute specular transmission.  Specular transmission
                 *  is always modified by material color.
                 */
                                                /* roughness + source */
                dtmp = np->alpha2 + omega/PI;
                                                /* gaussian */
                dtmp = exp((2.*DOT(np->prdir,ldir)-2.)/dtmp)/(PI*dtmp);
                                                /* worth using? */
                if (dtmp > FTINY) {
                        copycolor(ctmp, np->mcolor);
                        dtmp *= np->tspec * omega * sqrt(-ldot/np->pdot);
                        scalecolor(ctmp, dtmp);
                        addcolor(cval, ctmp);
                }
        }
}


m_normal(m, r)                  /* color a ray that hit something normal */
register OBJREC  *m;
register RAY  *r;
{
        NORMDAT  nd;
        double  transtest, transdist;
        COLOR  ctmp;
        register int  i;
                                                /* easy shadow test */
        if (r->crtype & SHADOW && m->otype != MAT_TRANS)
                return;

        if (m->oargs.nfargs != (m->otype == MAT_TRANS ? 7 : 5))
                objerror(m, USER, "bad number of 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.alpha2 = m->oargs.farg[4];
        if ((nd.alpha2 *= nd.alpha2) <= FTINY)
                nd.specfl |= SP_PURE;
                                                /* 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 dirnorm() */
        multcolor(nd.mcolor, r->pcol);          /* modify material color */
        transtest = 0;
                                                /* get specular component */
        if ((nd.rspec = m->oargs.farg[3]) > FTINY) {
                nd.specfl |= SP_REFL;
                                                /* compute specular color */
                if (m->otype == MAT_METAL)
                        copycolor(nd.scolor, nd.mcolor);
                else
                        setcolor(nd.scolor, 1.0, 1.0, 1.0);
                scalecolor(nd.scolor, nd.rspec);
                                                /* check threshold */
                if (!(nd.specfl & SP_PURE) && specthresh >= nd.rspec-FTINY)
                        nd.specfl |= SP_RBLT;
                                                /* compute reflected ray */
                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];

                if (!(r->crtype & SHADOW) && nd.specfl & SP_PURE) {
                        RAY  lr;
                        if (rayorigin(&lr, r, REFLECTED, nd.rspec) == 0) {
                                VCOPY(lr.rdir, nd.vrefl);
                                rayvalue(&lr);
                                multcolor(lr.rcol, nd.scolor);
                                addcolor(r->rcol, lr.rcol);
                        }
                }
        }
                                                /* compute transmission */
        if (m->otype == MAT_TRANS) {
                nd.trans = m->oargs.farg[5]*(1.0 - nd.rspec);
                nd.tspec = nd.trans * m->oargs.farg[6];
                nd.tdiff = nd.trans - nd.tspec;
                if (nd.tspec > FTINY) {
                        nd.specfl |= SP_TRAN;
                                                        /* check threshold */
                        if (!(nd.specfl & SP_PURE) &&
                                        specthresh >= nd.tspec-FTINY)
                                nd.specfl |= SP_TBLT;
                        if (r->crtype & SHADOW ||
                                        DOT(r->pert,r->pert) <= FTINY*FTINY) {
                                VCOPY(nd.prdir, r->rdir);
                                transtest = 2;
                        } 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;
                                                /* transmitted ray */
        if ((nd.specfl&(SP_TRAN|SP_PURE)) == (SP_TRAN|SP_PURE)) {
                RAY  lr;
                if (rayorigin(&lr, r, TRANS, nd.tspec) == 0) {
                        VCOPY(lr.rdir, nd.prdir);
                        rayvalue(&lr);
                        scalecolor(lr.rcol, nd.tspec);
                        multcolor(lr.rcol, nd.mcolor);  /* modified by color */
                        addcolor(r->rcol, lr.rcol);
                        transtest *= bright(lr.rcol);
                        transdist = r->rot + lr.rt;
                }
        } else
                transtest = 0;

        if (r->crtype & SHADOW)                 /* the rest is shadow */
                return;
                                                /* diffuse reflection */
        nd.rdiff = 1.0 - nd.trans - nd.rspec;

        if (nd.specfl & SP_PURE && nd.rdiff <= FTINY && nd.tdiff <= FTINY)
                return;                         /* 100% pure specular */

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

        if (nd.specfl & (SP_REFL|SP_TRAN) && !(nd.specfl & SP_PURE))
                gaussamp(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, dirnorm, &nd);
                                        /* check distance */
        if (transtest > bright(r->rcol))
                r->rt = transdist;
}


static
gaussamp(r, np)                 /* sample gaussian specular */
RAY  *r;
register NORMDAT  *np;
{
        RAY  sr;
        FVECT  u, v, h;
        double  rv[2];
        double  d, sinp, cosp;
        register int  i;
                                        /* quick test */
        if ((np->specfl & (SP_REFL|SP_RBLT)) != SP_REFL &&
                        (np->specfl & (SP_TRAN|SP_TBLT)) != SP_TRAN)
                return;
                                        /* set up sample coordinates */
        v[0] = v[1] = v[2] = 0.0;
        for (i = 0; i < 3; i++)
                if (np->pnorm[i] < 0.6 && np->pnorm[i] > -0.6)
                        break;
        v[i] = 1.0;
        fcross(u, v, np->pnorm);
        normalize(u);
        fcross(v, np->pnorm, u);
                                        /* 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);
                sinp = sin(d);
                rv[1] = 1.0 - specjitter*rv[1];
                if (rv[1] <= FTINY)
                        d = 1.0;
                else
                        d = sqrt( np->alpha2 * -log(rv[1]) );
                for (i = 0; i < 3; i++)
                        h[i] = np->pnorm[i] + d*(cosp*u[i] + sinp*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)
                        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);
                sinp = sin(d);
                rv[1] = 1.0 - specjitter*rv[1];
                if (rv[1] <= FTINY)
                        d = 1.0;
                else
                        d = sqrt( -log(rv[1]) * np->alpha2 );
                for (i = 0; i < 3; i++)
                        sr.rdir[i] = np->prdir[i] + d*(cosp*u[i] + sinp*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);         /* modified by color */
                addcolor(r->rcol, sr.rcol);
                ndims--;
        }
}
Revision:	2.25
Committed:	Thu May 27 15:28:03 1993 UTC (30 years, 11 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.24:	+3 -15 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	2.2	/* Copyright (c) 1992 Regents of the University of California */
2	greg	1.1
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* normal.c - shading function for normal materials.
9			*
10			* 8/19/85
11			* 12/19/85 - added stuff for metals.
12			* 6/26/87 - improved specular model.
13			* 9/28/87 - added model for translucent materials.
14	greg	2.2	* Later changes described in delta comments.
15	greg	1.1	*/
16
17			#include "ray.h"
18
19			#include "otypes.h"
20
21	greg	2.2	#include "random.h"
22
23	greg	2.5	extern double specthresh; /* specular sampling threshold */
24			extern double specjitter; /* specular sampling jitter */
25
26	greg	2.24	static gaussamp();
27
28	greg	1.1	/*
29	greg	2.22	* This routine implements the isotropic Gaussian
30			* model described by Ward in Siggraph `92 article.
31	greg	1.1	* We orient the surface towards the incoming ray, so a single
32			* surface can be used to represent an infinitely thin object.
33			*
34			* Arguments for MAT_PLASTIC and MAT_METAL are:
35			* red grn blu specular-frac. facet-slope
36			*
37			* Arguments for MAT_TRANS are:
38			* red grn blu rspec rough trans tspec
39			*/
40
41	greg	2.2	/* specularity flags */
42			#define SP_REFL 01 /* has reflected specular component */
43			#define SP_TRAN 02 /* has transmitted specular */
44	greg	2.11	#define SP_PURE 04 /* purely specular (zero roughness) */
45			#define SP_FLAT 010 /* flat reflecting surface */
46			#define SP_RBLT 020 /* reflection below sample threshold */
47			#define SP_TBLT 040 /* transmission below threshold */
48	greg	1.1
49	greg	1.3	typedef struct {
50			OBJREC mp; / material pointer */
51	greg	2.16	RAY rp; / ray pointer */
52	greg	2.2	short specfl; /* specularity flags, defined above */
53	greg	1.1	COLOR mcolor; /* color of this material */
54			COLOR scolor; /* color of specular component */
55			FVECT vrefl; /* vector in direction of reflected ray */
56	greg	1.14	FVECT prdir; /* vector in transmitted direction */
57	greg	2.2	double alpha2; /* roughness squared */
58	greg	1.1	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	greg	1.3	} NORMDAT; /* normal material data */
64
65
66			dirnorm(cval, np, ldir, omega) /* compute source contribution */
67			COLOR cval; /* returned coefficient */
68			register NORMDAT np; / material data */
69			FVECT ldir; /* light source direction */
70			double omega; /* light source size */
71			{
72	greg	1.1	double ldot;
73	greg	2.16	double dtmp, d2;
74			FVECT vtmp;
75	greg	1.3	COLOR ctmp;
76
77			setcolor(cval, 0.0, 0.0, 0.0);
78
79			ldot = DOT(np->pnorm, ldir);
80
81			if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY)
82			return; /* wrong side */
83
84			if (ldot > FTINY && np->rdiff > FTINY) {
85			/*
86	greg	1.4	* Compute and add diffuse reflected component to returned
87			* color. The diffuse reflected component will always be
88			* modified by the color of the material.
89	greg	1.3	*/
90			copycolor(ctmp, np->mcolor);
91			dtmp = ldot * omega * np->rdiff / PI;
92			scalecolor(ctmp, dtmp);
93			addcolor(cval, ctmp);
94			}
95	greg	2.2	if (ldot > FTINY && (np->specfl&(SP_REFL\|SP_PURE)) == SP_REFL) {
96	greg	1.3	/*
97			* Compute specular reflection coefficient using
98			* gaussian distribution model.
99			*/
100	greg	2.3	/* roughness */
101	greg	2.16	dtmp = np->alpha2;
102	greg	2.3	/* + source if flat */
103			if (np->specfl & SP_FLAT)
104	greg	2.16	dtmp += omega/(4.0*PI);
105	greg	2.23	/* half vector */
106	greg	2.18	vtmp[0] = ldir[0] - np->rp->rdir[0];
107			vtmp[1] = ldir[1] - np->rp->rdir[1];
108			vtmp[2] = ldir[2] - np->rp->rdir[2];
109	greg	2.16	d2 = DOT(vtmp, np->pnorm);
110	greg	2.23	d2 *= d2;
111			d2 = (DOT(vtmp,vtmp) - d2) / d2;
112	greg	1.3	/* gaussian */
113	greg	2.16	dtmp = exp(-d2/dtmp)/(4.PIdtmp);
114	greg	1.3	/* worth using? */
115			if (dtmp > FTINY) {
116			copycolor(ctmp, np->scolor);
117	greg	2.14	dtmp = omega sqrt(ldot/np->pdot);
118	greg	1.3	scalecolor(ctmp, dtmp);
119			addcolor(cval, ctmp);
120			}
121			}
122			if (ldot < -FTINY && np->tdiff > FTINY) {
123			/*
124			* Compute diffuse transmission.
125			*/
126			copycolor(ctmp, np->mcolor);
127			dtmp = -ldot * omega * np->tdiff / PI;
128			scalecolor(ctmp, dtmp);
129			addcolor(cval, ctmp);
130			}
131	greg	2.2	if (ldot < -FTINY && (np->specfl&(SP_TRAN\|SP_PURE)) == SP_TRAN) {
132	greg	1.3	/*
133	greg	1.4	* Compute specular transmission. Specular transmission
134	greg	1.13	* is always modified by material color.
135	greg	1.3	*/
136			/* roughness + source */
137	greg	2.19	dtmp = np->alpha2 + omega/PI;
138	greg	1.3	/* gaussian */
139	greg	2.21	dtmp = exp((2.DOT(np->prdir,ldir)-2.)/dtmp)/(PIdtmp);
140	greg	1.3	/* worth using? */
141			if (dtmp > FTINY) {
142	greg	1.13	copycolor(ctmp, np->mcolor);
143	greg	2.18	dtmp = np->tspec omega * sqrt(-ldot/np->pdot);
144	greg	1.13	scalecolor(ctmp, dtmp);
145	greg	1.3	addcolor(cval, ctmp);
146			}
147			}
148			}
149
150
151	greg	2.2	m_normal(m, r) /* color a ray that hit something normal */
152	greg	1.3	register OBJREC *m;
153			register RAY *r;
154			{
155			NORMDAT nd;
156	greg	1.9	double transtest, transdist;
157	greg	1.1	COLOR ctmp;
158			register int i;
159			/* easy shadow test */
160			if (r->crtype & SHADOW && m->otype != MAT_TRANS)
161			return;
162	greg	2.2
163			if (m->oargs.nfargs != (m->otype == MAT_TRANS ? 7 : 5))
164			objerror(m, USER, "bad number of arguments");
165	greg	1.3	nd.mp = m;
166	greg	2.16	nd.rp = r;
167	greg	1.1	/* get material color */
168	greg	1.3	setcolor(nd.mcolor, m->oargs.farg[0],
169	greg	1.1	m->oargs.farg[1],
170			m->oargs.farg[2]);
171			/* get roughness */
172	greg	2.2	nd.specfl = 0;
173	greg	1.3	nd.alpha2 = m->oargs.farg[4];
174	greg	2.2	if ((nd.alpha2 *= nd.alpha2) <= FTINY)
175			nd.specfl \|= SP_PURE;
176	greg	1.1	/* reorient if necessary */
177			if (r->rod < 0.0)
178			flipsurface(r);
179			/* get modifiers */
180			raytexture(r, m->omod);
181	greg	1.3	nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */
182	greg	1.13	if (nd.pdot < .001)
183			nd.pdot = .001; /* non-zero for dirnorm() */
184	greg	1.3	multcolor(nd.mcolor, r->pcol); /* modify material color */
185	greg	1.9	transtest = 0;
186	greg	1.1	/* get specular component */
187	greg	2.2	if ((nd.rspec = m->oargs.farg[3]) > FTINY) {
188			nd.specfl \|= SP_REFL;
189	greg	1.1	/* compute specular color */
190			if (m->otype == MAT_METAL)
191	greg	1.3	copycolor(nd.scolor, nd.mcolor);
192	greg	1.1	else
193	greg	1.3	setcolor(nd.scolor, 1.0, 1.0, 1.0);
194			scalecolor(nd.scolor, nd.rspec);
195	greg	2.15	/* check threshold */
196	greg	2.25	if (!(nd.specfl & SP_PURE) && specthresh >= nd.rspec-FTINY)
197	greg	2.5	nd.specfl \|= SP_RBLT;
198	greg	1.1	/* compute reflected ray */
199			for (i = 0; i < 3; i++)
200	greg	1.3	nd.vrefl[i] = r->rdir[i] + 2.0nd.pdotnd.pnorm[i];
201	greg	2.7	if (DOT(nd.vrefl, r->ron) <= FTINY) /* penetration? */
202			for (i = 0; i < 3; i++) /* safety measure */
203			nd.vrefl[i] = r->rdir[i] + 2.r->rodr->ron[i];
204	greg	1.1
205	greg	2.2	if (!(r->crtype & SHADOW) && nd.specfl & SP_PURE) {
206	greg	1.3	RAY lr;
207			if (rayorigin(&lr, r, REFLECTED, nd.rspec) == 0) {
208			VCOPY(lr.rdir, nd.vrefl);
209	greg	1.1	rayvalue(&lr);
210	greg	1.3	multcolor(lr.rcol, nd.scolor);
211	greg	1.1	addcolor(r->rcol, lr.rcol);
212			}
213	greg	1.3	}
214	greg	1.1	}
215	greg	1.3	/* compute transmission */
216	greg	1.1	if (m->otype == MAT_TRANS) {
217	greg	1.3	nd.trans = m->oargs.farg[5]*(1.0 - nd.rspec);
218			nd.tspec = nd.trans * m->oargs.farg[6];
219			nd.tdiff = nd.trans - nd.tspec;
220	greg	2.2	if (nd.tspec > FTINY) {
221			nd.specfl \|= SP_TRAN;
222	greg	2.5	/* check threshold */
223	greg	2.25	if (!(nd.specfl & SP_PURE) &&
224			specthresh >= nd.tspec-FTINY)
225	greg	2.5	nd.specfl \|= SP_TBLT;
226	greg	2.2	if (r->crtype & SHADOW \|\|
227			DOT(r->pert,r->pert) <= FTINY*FTINY) {
228			VCOPY(nd.prdir, r->rdir);
229			transtest = 2;
230			} else {
231			for (i = 0; i < 3; i++) /* perturb */
232	greg	2.19	nd.prdir[i] = r->rdir[i] - r->pert[i];
233	greg	2.7	if (DOT(nd.prdir, r->ron) < -FTINY)
234			normalize(nd.prdir); /* OK */
235			else
236			VCOPY(nd.prdir, r->rdir);
237	greg	2.2	}
238	greg	1.14	}
239	greg	1.1	} else
240	greg	1.3	nd.tdiff = nd.tspec = nd.trans = 0.0;
241	greg	1.1	/* transmitted ray */
242	greg	2.2	if ((nd.specfl&(SP_TRAN\|SP_PURE)) == (SP_TRAN\|SP_PURE)) {
243	greg	1.3	RAY lr;
244			if (rayorigin(&lr, r, TRANS, nd.tspec) == 0) {
245	greg	1.14	VCOPY(lr.rdir, nd.prdir);
246	greg	1.1	rayvalue(&lr);
247	greg	1.3	scalecolor(lr.rcol, nd.tspec);
248	greg	1.8	multcolor(lr.rcol, nd.mcolor); /* modified by color */
249	greg	1.1	addcolor(r->rcol, lr.rcol);
250	greg	1.9	transtest *= bright(lr.rcol);
251			transdist = r->rot + lr.rt;
252	greg	1.1	}
253	greg	2.11	} else
254			transtest = 0;
255	greg	2.2
256	greg	1.1	if (r->crtype & SHADOW) /* the rest is shadow */
257			return;
258			/* diffuse reflection */
259	greg	1.3	nd.rdiff = 1.0 - nd.trans - nd.rspec;
260	greg	1.1
261	greg	2.2	if (nd.specfl & SP_PURE && nd.rdiff <= FTINY && nd.tdiff <= FTINY)
262			return; /* 100% pure specular */
263	greg	2.3
264	greg	2.12	if (r->ro != NULL && (r->ro->otype == OBJ_FACE \|\|
265			r->ro->otype == OBJ_RING))
266	greg	2.3	nd.specfl \|= SP_FLAT;
267	greg	1.1
268	greg	2.2	if (nd.specfl & (SP_REFL\|SP_TRAN) && !(nd.specfl & SP_PURE))
269			gaussamp(r, &nd);
270
271	greg	1.3	if (nd.rdiff > FTINY) { /* ambient from this side */
272	greg	1.2	ambient(ctmp, r);
273	greg	2.5	if (nd.specfl & SP_RBLT)
274			scalecolor(ctmp, 1.0-nd.trans);
275			else
276			scalecolor(ctmp, nd.rdiff);
277	greg	1.3	multcolor(ctmp, nd.mcolor); /* modified by material color */
278	greg	1.2	addcolor(r->rcol, ctmp); /* add to returned color */
279			}
280	greg	1.3	if (nd.tdiff > FTINY) { /* ambient from other side */
281	greg	1.1	flipsurface(r);
282	greg	1.2	ambient(ctmp, r);
283	greg	2.5	if (nd.specfl & SP_TBLT)
284			scalecolor(ctmp, nd.trans);
285			else
286			scalecolor(ctmp, nd.tdiff);
287	greg	1.13	multcolor(ctmp, nd.mcolor); /* modified by color */
288	greg	1.1	addcolor(r->rcol, ctmp);
289			flipsurface(r);
290			}
291	greg	1.3	/* add direct component */
292			direct(r, dirnorm, &nd);
293	greg	1.9	/* check distance */
294			if (transtest > bright(r->rcol))
295			r->rt = transdist;
296	greg	2.2	}
297
298
299			static
300			gaussamp(r, np) /* sample gaussian specular */
301			RAY *r;
302			register NORMDAT *np;
303			{
304			RAY sr;
305			FVECT u, v, h;
306			double rv[2];
307			double d, sinp, cosp;
308			register int i;
309	greg	2.13	/* quick test */
310			if ((np->specfl & (SP_REFL\|SP_RBLT)) != SP_REFL &&
311			(np->specfl & (SP_TRAN\|SP_TBLT)) != SP_TRAN)
312			return;
313	greg	2.2	/* set up sample coordinates */
314			v[0] = v[1] = v[2] = 0.0;
315			for (i = 0; i < 3; i++)
316			if (np->pnorm[i] < 0.6 && np->pnorm[i] > -0.6)
317			break;
318			v[i] = 1.0;
319			fcross(u, v, np->pnorm);
320			normalize(u);
321			fcross(v, np->pnorm, u);
322			/* compute reflection */
323	greg	2.5	if ((np->specfl & (SP_REFL\|SP_RBLT)) == SP_REFL &&
324	greg	2.2	rayorigin(&sr, r, SPECULAR, np->rspec) == 0) {
325			dimlist[ndims++] = (int)np->mp;
326	greg	2.7	d = urand(ilhash(dimlist,ndims)+samplendx);
327			multisamp(rv, 2, d);
328			d = 2.0PI rv[0];
329			cosp = cos(d);
330			sinp = sin(d);
331			rv[1] = 1.0 - specjitter*rv[1];
332			if (rv[1] <= FTINY)
333			d = 1.0;
334			else
335			d = sqrt( np->alpha2 * -log(rv[1]) );
336			for (i = 0; i < 3; i++)
337			h[i] = np->pnorm[i] + d(cospu[i] + sinp*v[i]);
338			d = -2.0 * DOT(h, r->rdir) / (1.0 + d*d);
339			for (i = 0; i < 3; i++)
340			sr.rdir[i] = r->rdir[i] + d*h[i];
341			if (DOT(sr.rdir, r->ron) <= FTINY)
342			VCOPY(sr.rdir, np->vrefl); /* jitter no good */
343			rayvalue(&sr);
344			multcolor(sr.rcol, np->scolor);
345			addcolor(r->rcol, sr.rcol);
346	greg	2.2	ndims--;
347			}
348			/* compute transmission */
349	greg	2.8	if ((np->specfl & (SP_TRAN\|SP_TBLT)) == SP_TRAN &&
350			rayorigin(&sr, r, SPECULAR, np->tspec) == 0) {
351			dimlist[ndims++] = (int)np->mp;
352			d = urand(ilhash(dimlist,ndims)+1823+samplendx);
353			multisamp(rv, 2, d);
354			d = 2.0PI rv[0];
355			cosp = cos(d);
356			sinp = sin(d);
357			rv[1] = 1.0 - specjitter*rv[1];
358			if (rv[1] <= FTINY)
359			d = 1.0;
360			else
361	greg	2.20	d = sqrt( -log(rv[1]) * np->alpha2 );
362	greg	2.8	for (i = 0; i < 3; i++)
363			sr.rdir[i] = np->prdir[i] + d(cospu[i] + sinp*v[i]);
364			if (DOT(sr.rdir, r->ron) < -FTINY)
365			normalize(sr.rdir); /* OK, normalize */
366			else
367			VCOPY(sr.rdir, np->prdir); /* else no jitter */
368			rayvalue(&sr);
369	greg	2.11	scalecolor(sr.rcol, np->tspec);
370			multcolor(sr.rcol, np->mcolor); /* modified by color */
371	greg	2.8	addcolor(r->rcol, sr.rcol);
372			ndims--;
373			}
374	greg	1.1	}