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"

/*
 *      This routine uses portions of the reflection
 *  model described by Cook and Torrance.
 *      The computation of specular components has been simplified by
 *  numerous approximations and ommisions to improve speed.
 *      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
 */

#define  BSPEC(m)       (6.0)           /* specularity parameter b */

                                /* specularity flags */
#define  SP_REFL        01              /* has reflected specular component */
#define  SP_TRAN        02              /* has transmitted specular */
#define  SP_PURE        010             /* purely specular (zero roughness) */
#define  SP_FLAT        020             /* flat reflecting surface */

typedef struct {
        OBJREC  *mp;            /* material 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;
        int     i;
        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 = 2.0*np->alpha2;
                                                /* + source if flat */
                if (np->specfl & SP_FLAT)
                        dtmp += omega/(2.0*PI);
                                                /* gaussian */
                dtmp = exp((DOT(np->vrefl,ldir)-1.)/dtmp)/(2.*PI)/dtmp;
                                                /* worth using? */
                if (dtmp > FTINY) {
                        copycolor(ctmp, np->scolor);
                        dtmp *= omega / 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/(2.0*PI);
                                                /* gaussian */
                dtmp = exp((DOT(np->prdir,ldir)-1.)/dtmp)/(2.*PI)/dtmp;
                                                /* worth using? */
                if (dtmp > FTINY) {
                        copycolor(ctmp, np->mcolor);
                        dtmp *= np->tspec * omega / 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;
        double  dtmp;
        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;
                                                /* 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);
                                                /* improved model */
                dtmp = exp(-BSPEC(m)*nd.pdot);
                for (i = 0; i < 3; i++)
                        colval(nd.scolor,i) += (1.0-colval(nd.scolor,i))*dtmp;
                nd.rspec += (1.0-nd.rspec)*dtmp;
                                                /* compute reflected ray */
                for (i = 0; i < 3; i++)
                        nd.vrefl[i] = r->rdir[i] + 2.0*nd.pdot*nd.pnorm[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;
                        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] -
                                                        .75*r->pert[i];
                                normalize(nd.prdir);
                        }
                }
        } 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;
                }
        }

        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->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);
                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);
                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;
        int  ntries;
        register int  i;
                                        /* 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 &&
                        rayorigin(&sr, r, SPECULAR, np->rspec) == 0) {
                dimlist[ndims++] = (int)np->mp;
                for (ntries = 0; ntries < 10; ntries++) {
                        dimlist[ndims] = ntries * 8912;
                        d = urand(ilhash(dimlist,ndims+1)+samplendx);
                        multisamp(rv, 2, d);
                        d = 2.0*PI * rv[0];
                        cosp = cos(d);
                        sinp = sin(d);
                        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) {
                                rayvalue(&sr);
                                multcolor(sr.rcol, np->scolor);
                                addcolor(r->rcol, sr.rcol);
                                break;
                        }
                }
                ndims--;
        }
                                        /* compute transmission */
}
Revision:	2.4
Committed:	Tue Jan 14 15:33:08 1992 UTC (32 years, 3 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.3:	+24 -23 lines
Log Message:	fixed bug in sampling code
#	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	1.1	/*
24			* This routine uses portions of the reflection
25			* model described by Cook and Torrance.
26			* The computation of specular components has been simplified by
27			* numerous approximations and ommisions to improve speed.
28			* We orient the surface towards the incoming ray, so a single
29			* surface can be used to represent an infinitely thin object.
30			*
31			* Arguments for MAT_PLASTIC and MAT_METAL are:
32			* red grn blu specular-frac. facet-slope
33			*
34			* Arguments for MAT_TRANS are:
35			* red grn blu rspec rough trans tspec
36			*/
37
38			#define BSPEC(m) (6.0) /* specularity parameter b */
39
40	greg	2.2	/* specularity flags */
41			#define SP_REFL 01 /* has reflected specular component */
42			#define SP_TRAN 02 /* has transmitted specular */
43			#define SP_PURE 010 /* purely specular (zero roughness) */
44	greg	2.3	#define SP_FLAT 020 /* flat reflecting surface */
45	greg	1.1
46	greg	1.3	typedef struct {
47			OBJREC mp; / material pointer */
48	greg	2.2	short specfl; /* specularity flags, defined above */
49	greg	1.1	COLOR mcolor; /* color of this material */
50			COLOR scolor; /* color of specular component */
51			FVECT vrefl; /* vector in direction of reflected ray */
52	greg	1.14	FVECT prdir; /* vector in transmitted direction */
53	greg	2.2	double alpha2; /* roughness squared */
54	greg	1.1	double rdiff, rspec; /* reflected specular, diffuse */
55			double trans; /* transmissivity */
56			double tdiff, tspec; /* transmitted specular, diffuse */
57			FVECT pnorm; /* perturbed surface normal */
58			double pdot; /* perturbed dot product */
59	greg	1.3	} NORMDAT; /* normal material data */
60
61
62			dirnorm(cval, np, ldir, omega) /* compute source contribution */
63			COLOR cval; /* returned coefficient */
64			register NORMDAT np; / material data */
65			FVECT ldir; /* light source direction */
66			double omega; /* light source size */
67			{
68	greg	1.1	double ldot;
69	greg	1.3	double dtmp;
70	greg	2.3	int i;
71	greg	1.3	COLOR ctmp;
72
73			setcolor(cval, 0.0, 0.0, 0.0);
74
75			ldot = DOT(np->pnorm, ldir);
76
77			if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY)
78			return; /* wrong side */
79
80			if (ldot > FTINY && np->rdiff > FTINY) {
81			/*
82	greg	1.4	* Compute and add diffuse reflected component to returned
83			* color. The diffuse reflected component will always be
84			* modified by the color of the material.
85	greg	1.3	*/
86			copycolor(ctmp, np->mcolor);
87			dtmp = ldot * omega * np->rdiff / PI;
88			scalecolor(ctmp, dtmp);
89			addcolor(cval, ctmp);
90			}
91	greg	2.2	if (ldot > FTINY && (np->specfl&(SP_REFL\|SP_PURE)) == SP_REFL) {
92	greg	1.3	/*
93			* Compute specular reflection coefficient using
94			* gaussian distribution model.
95			*/
96	greg	2.3	/* roughness */
97			dtmp = 2.0*np->alpha2;
98			/* + source if flat */
99			if (np->specfl & SP_FLAT)
100			dtmp += omega/(2.0*PI);
101	greg	1.3	/* gaussian */
102			dtmp = exp((DOT(np->vrefl,ldir)-1.)/dtmp)/(2.*PI)/dtmp;
103			/* worth using? */
104			if (dtmp > FTINY) {
105			copycolor(ctmp, np->scolor);
106	greg	1.13	dtmp *= omega / np->pdot;
107	greg	1.3	scalecolor(ctmp, dtmp);
108			addcolor(cval, ctmp);
109			}
110			}
111			if (ldot < -FTINY && np->tdiff > FTINY) {
112			/*
113			* Compute diffuse transmission.
114			*/
115			copycolor(ctmp, np->mcolor);
116			dtmp = -ldot * omega * np->tdiff / PI;
117			scalecolor(ctmp, dtmp);
118			addcolor(cval, ctmp);
119			}
120	greg	2.2	if (ldot < -FTINY && (np->specfl&(SP_TRAN\|SP_PURE)) == SP_TRAN) {
121	greg	1.3	/*
122	greg	1.4	* Compute specular transmission. Specular transmission
123	greg	1.13	* is always modified by material color.
124	greg	1.3	*/
125			/* roughness + source */
126			dtmp = np->alpha2 + omega/(2.0*PI);
127			/* gaussian */
128	greg	1.14	dtmp = exp((DOT(np->prdir,ldir)-1.)/dtmp)/(2.*PI)/dtmp;
129	greg	1.3	/* worth using? */
130			if (dtmp > FTINY) {
131	greg	1.13	copycolor(ctmp, np->mcolor);
132			dtmp = np->tspec omega / np->pdot;
133			scalecolor(ctmp, dtmp);
134	greg	1.3	addcolor(cval, ctmp);
135			}
136			}
137			}
138
139
140	greg	2.2	m_normal(m, r) /* color a ray that hit something normal */
141	greg	1.3	register OBJREC *m;
142			register RAY *r;
143			{
144			NORMDAT nd;
145	greg	1.9	double transtest, transdist;
146	greg	1.1	double dtmp;
147			COLOR ctmp;
148			register int i;
149			/* easy shadow test */
150			if (r->crtype & SHADOW && m->otype != MAT_TRANS)
151			return;
152	greg	2.2
153			if (m->oargs.nfargs != (m->otype == MAT_TRANS ? 7 : 5))
154			objerror(m, USER, "bad number of arguments");
155	greg	1.3	nd.mp = m;
156	greg	1.1	/* get material color */
157	greg	1.3	setcolor(nd.mcolor, m->oargs.farg[0],
158	greg	1.1	m->oargs.farg[1],
159			m->oargs.farg[2]);
160			/* get roughness */
161	greg	2.2	nd.specfl = 0;
162	greg	1.3	nd.alpha2 = m->oargs.farg[4];
163	greg	2.2	if ((nd.alpha2 *= nd.alpha2) <= FTINY)
164			nd.specfl \|= SP_PURE;
165	greg	1.1	/* reorient if necessary */
166			if (r->rod < 0.0)
167			flipsurface(r);
168			/* get modifiers */
169			raytexture(r, m->omod);
170	greg	1.3	nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */
171	greg	1.13	if (nd.pdot < .001)
172			nd.pdot = .001; /* non-zero for dirnorm() */
173	greg	1.3	multcolor(nd.mcolor, r->pcol); /* modify material color */
174	greg	1.9	transtest = 0;
175	greg	1.1	/* get specular component */
176	greg	2.2	if ((nd.rspec = m->oargs.farg[3]) > FTINY) {
177			nd.specfl \|= SP_REFL;
178	greg	1.1	/* compute specular color */
179			if (m->otype == MAT_METAL)
180	greg	1.3	copycolor(nd.scolor, nd.mcolor);
181	greg	1.1	else
182	greg	1.3	setcolor(nd.scolor, 1.0, 1.0, 1.0);
183			scalecolor(nd.scolor, nd.rspec);
184	greg	1.1	/* improved model */
185	greg	1.3	dtmp = exp(-BSPEC(m)*nd.pdot);
186	greg	1.1	for (i = 0; i < 3; i++)
187	greg	1.3	colval(nd.scolor,i) += (1.0-colval(nd.scolor,i))*dtmp;
188			nd.rspec += (1.0-nd.rspec)*dtmp;
189	greg	1.1	/* compute reflected ray */
190			for (i = 0; i < 3; i++)
191	greg	1.3	nd.vrefl[i] = r->rdir[i] + 2.0nd.pdotnd.pnorm[i];
192	greg	1.1
193	greg	2.2	if (!(r->crtype & SHADOW) && nd.specfl & SP_PURE) {
194	greg	1.3	RAY lr;
195			if (rayorigin(&lr, r, REFLECTED, nd.rspec) == 0) {
196			VCOPY(lr.rdir, nd.vrefl);
197	greg	1.1	rayvalue(&lr);
198	greg	1.3	multcolor(lr.rcol, nd.scolor);
199	greg	1.1	addcolor(r->rcol, lr.rcol);
200			}
201	greg	1.3	}
202	greg	1.1	}
203	greg	1.3	/* compute transmission */
204	greg	1.1	if (m->otype == MAT_TRANS) {
205	greg	1.3	nd.trans = m->oargs.farg[5]*(1.0 - nd.rspec);
206			nd.tspec = nd.trans * m->oargs.farg[6];
207			nd.tdiff = nd.trans - nd.tspec;
208	greg	2.2	if (nd.tspec > FTINY) {
209			nd.specfl \|= SP_TRAN;
210			if (r->crtype & SHADOW \|\|
211			DOT(r->pert,r->pert) <= FTINY*FTINY) {
212			VCOPY(nd.prdir, r->rdir);
213			transtest = 2;
214			} else {
215			for (i = 0; i < 3; i++) /* perturb */
216			nd.prdir[i] = r->rdir[i] -
217			.75*r->pert[i];
218			normalize(nd.prdir);
219			}
220	greg	1.14	}
221	greg	1.1	} else
222	greg	1.3	nd.tdiff = nd.tspec = nd.trans = 0.0;
223	greg	1.1	/* transmitted ray */
224	greg	2.2	if ((nd.specfl&(SP_TRAN\|SP_PURE)) == (SP_TRAN\|SP_PURE)) {
225	greg	1.3	RAY lr;
226			if (rayorigin(&lr, r, TRANS, nd.tspec) == 0) {
227	greg	1.14	VCOPY(lr.rdir, nd.prdir);
228	greg	1.1	rayvalue(&lr);
229	greg	1.3	scalecolor(lr.rcol, nd.tspec);
230	greg	1.8	multcolor(lr.rcol, nd.mcolor); /* modified by color */
231	greg	1.1	addcolor(r->rcol, lr.rcol);
232	greg	1.9	transtest *= bright(lr.rcol);
233			transdist = r->rot + lr.rt;
234	greg	1.1	}
235	greg	1.3	}
236	greg	2.2
237	greg	1.1	if (r->crtype & SHADOW) /* the rest is shadow */
238			return;
239			/* diffuse reflection */
240	greg	1.3	nd.rdiff = 1.0 - nd.trans - nd.rspec;
241	greg	1.1
242	greg	2.2	if (nd.specfl & SP_PURE && nd.rdiff <= FTINY && nd.tdiff <= FTINY)
243			return; /* 100% pure specular */
244	greg	2.3
245			if (r->ro->otype == OBJ_FACE \|\| r->ro->otype == OBJ_RING)
246			nd.specfl \|= SP_FLAT;
247	greg	1.1
248	greg	2.2	if (nd.specfl & (SP_REFL\|SP_TRAN) && !(nd.specfl & SP_PURE))
249			gaussamp(r, &nd);
250
251	greg	1.3	if (nd.rdiff > FTINY) { /* ambient from this side */
252	greg	1.2	ambient(ctmp, r);
253	greg	2.2	scalecolor(ctmp, nd.rdiff);
254	greg	1.3	multcolor(ctmp, nd.mcolor); /* modified by material color */
255	greg	1.2	addcolor(r->rcol, ctmp); /* add to returned color */
256			}
257	greg	1.3	if (nd.tdiff > FTINY) { /* ambient from other side */
258	greg	1.1	flipsurface(r);
259	greg	1.2	ambient(ctmp, r);
260	greg	2.2	scalecolor(ctmp, nd.tdiff);
261	greg	1.13	multcolor(ctmp, nd.mcolor); /* modified by color */
262	greg	1.1	addcolor(r->rcol, ctmp);
263			flipsurface(r);
264			}
265	greg	1.3	/* add direct component */
266			direct(r, dirnorm, &nd);
267	greg	1.9	/* check distance */
268			if (transtest > bright(r->rcol))
269			r->rt = transdist;
270	greg	2.2	}
271
272
273			static
274			gaussamp(r, np) /* sample gaussian specular */
275			RAY *r;
276			register NORMDAT *np;
277			{
278			RAY sr;
279			FVECT u, v, h;
280			double rv[2];
281			double d, sinp, cosp;
282	greg	2.4	int ntries;
283	greg	2.2	register int i;
284			/* set up sample coordinates */
285			v[0] = v[1] = v[2] = 0.0;
286			for (i = 0; i < 3; i++)
287			if (np->pnorm[i] < 0.6 && np->pnorm[i] > -0.6)
288			break;
289			v[i] = 1.0;
290			fcross(u, v, np->pnorm);
291			normalize(u);
292			fcross(v, np->pnorm, u);
293			/* compute reflection */
294			if (np->specfl & SP_REFL &&
295			rayorigin(&sr, r, SPECULAR, np->rspec) == 0) {
296			dimlist[ndims++] = (int)np->mp;
297	greg	2.4	for (ntries = 0; ntries < 10; ntries++) {
298			dimlist[ndims] = ntries * 8912;
299			d = urand(ilhash(dimlist,ndims+1)+samplendx);
300			multisamp(rv, 2, d);
301			d = 2.0PI rv[0];
302			cosp = cos(d);
303			sinp = sin(d);
304			if (rv[1] <= FTINY)
305			d = 1.0;
306			else
307			d = sqrt( np->alpha2 * -log(rv[1]) );
308			for (i = 0; i < 3; i++)
309			h[i] = np->pnorm[i] + d(cospu[i] + sinp*v[i]);
310			d = -2.0 * DOT(h, r->rdir) / (1.0 + d*d);
311			for (i = 0; i < 3; i++)
312			sr.rdir[i] = r->rdir[i] + d*h[i];
313			if (DOT(sr.rdir, r->ron) > FTINY) {
314			rayvalue(&sr);
315			multcolor(sr.rcol, np->scolor);
316			addcolor(r->rcol, sr.rcol);
317			break;
318			}
319			}
320	greg	2.2	ndims--;
321			}
322			/* compute transmission */
323	greg	1.1	}