src/rt/normal.c

/* Copyright (c) 1991 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.
 */

#include  "ray.h"

#include  "otypes.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 */

extern double  exp();

typedef struct {
        OBJREC  *mp;            /* material pointer */
        RAY  *pr;               /* intersected ray */
        COLOR  mcolor;          /* color of this material */
        COLOR  scolor;          /* color of specular component */
        FVECT  vrefl;           /* vector in direction of reflected ray */
        double  alpha2;         /* roughness squared times 2 */
        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;
        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->rspec > FTINY && np->alpha2 > FTINY) {
                /*
                 *  Compute specular reflection coefficient using
                 *  gaussian distribution model.
                 */
                                                /* roughness + source */
                dtmp = np->alpha2 + 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->tspec > FTINY && np->alpha2 > FTINY) {
                /*
                 *  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->pr->rdir,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 which hit something normal */
register OBJREC  *m;
register RAY  *r;
{
        NORMDAT  nd;
        double  transtest, transdist;
        double  dtmp;
        COLOR  ctmp;
        register int  i;

        if (m->oargs.nfargs != (m->otype == MAT_TRANS ? 7 : 5))
                objerror(m, USER, "bad # arguments");
                                                /* easy shadow test */
        if (r->crtype & SHADOW && m->otype != MAT_TRANS)
                return;
        nd.mp = m;
        nd.pr = r;
                                                /* get material color */
        setcolor(nd.mcolor, m->oargs.farg[0],
                           m->oargs.farg[1],
                           m->oargs.farg[2]);
                                                /* get roughness */
        nd.alpha2 = m->oargs.farg[4];
        nd.alpha2 *= 2.0 * nd.alpha2;
                                                /* 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 */
        nd.rspec = m->oargs.farg[3];

        if (nd.rspec > FTINY) {                 /* has specular component */
                                                /* 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 (nd.alpha2 <= FTINY && !(r->crtype & SHADOW)) {
                        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;
        } else
                nd.tdiff = nd.tspec = nd.trans = 0.0;
                                                /* transmitted ray */
        if (nd.tspec > FTINY && nd.alpha2 <= FTINY) {
                RAY  lr;
                if (rayorigin(&lr, r, TRANS, nd.tspec) == 0) {
                        if (!(r->crtype & SHADOW) &&
                                        DOT(r->pert,r->pert) > FTINY*FTINY) {
                                for (i = 0; i < 3; i++) /* perturb direction */
                                        lr.rdir[i] = r->rdir[i] -
                                                        .75*r->pert[i];
                                normalize(lr.rdir);
                        } else {
                                VCOPY(lr.rdir, r->rdir);
                                transtest = 2;
                        }
                        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.rdiff <= FTINY && nd.tdiff <= FTINY && nd.alpha2 <= FTINY)
                return;                         /* purely specular */

        if (nd.rdiff > FTINY) {         /* ambient from this side */
                ambient(ctmp, r);
                if (nd.alpha2 <= FTINY)
                        scalecolor(ctmp, nd.rdiff);
                else
                        scalecolor(ctmp, 1.0-nd.trans);
                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.alpha2 <= FTINY)
                        scalecolor(ctmp, nd.tdiff);
                else
                        scalecolor(ctmp, nd.trans);
                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;
}
Revision:	1.13
Committed:	Wed Oct 30 10:59:42 1991 UTC (34 years ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.12:	+8 -5 lines
Log Message:	made gaussian component bidirectional with addition of cosine term
#	User	Rev	Content
1	greg	1.9	/* Copyright (c) 1991 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			*/
15
16			#include "ray.h"
17
18			#include "otypes.h"
19
20			/*
21			* This routine uses portions of the reflection
22			* model described by Cook and Torrance.
23			* The computation of specular components has been simplified by
24			* numerous approximations and ommisions to improve speed.
25			* We orient the surface towards the incoming ray, so a single
26			* surface can be used to represent an infinitely thin object.
27			*
28			* Arguments for MAT_PLASTIC and MAT_METAL are:
29			* red grn blu specular-frac. facet-slope
30			*
31			* Arguments for MAT_TRANS are:
32			* red grn blu rspec rough trans tspec
33			*/
34
35			#define BSPEC(m) (6.0) /* specularity parameter b */
36
37	greg	1.3	extern double exp();
38	greg	1.1
39	greg	1.3	typedef struct {
40			OBJREC mp; / material pointer */
41			RAY pr; / intersected ray */
42	greg	1.1	COLOR mcolor; /* color of this material */
43			COLOR scolor; /* color of specular component */
44			FVECT vrefl; /* vector in direction of reflected ray */
45			double alpha2; /* roughness squared times 2 */
46			double rdiff, rspec; /* reflected specular, diffuse */
47			double trans; /* transmissivity */
48			double tdiff, tspec; /* transmitted specular, diffuse */
49			FVECT pnorm; /* perturbed surface normal */
50			double pdot; /* perturbed dot product */
51	greg	1.3	} NORMDAT; /* normal material data */
52
53
54			dirnorm(cval, np, ldir, omega) /* compute source contribution */
55			COLOR cval; /* returned coefficient */
56			register NORMDAT np; / material data */
57			FVECT ldir; /* light source direction */
58			double omega; /* light source size */
59			{
60	greg	1.1	double ldot;
61	greg	1.3	double dtmp;
62			COLOR ctmp;
63
64			setcolor(cval, 0.0, 0.0, 0.0);
65
66			ldot = DOT(np->pnorm, ldir);
67
68			if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY)
69			return; /* wrong side */
70
71			if (ldot > FTINY && np->rdiff > FTINY) {
72			/*
73	greg	1.4	* Compute and add diffuse reflected component to returned
74			* color. The diffuse reflected component will always be
75			* modified by the color of the material.
76	greg	1.3	*/
77			copycolor(ctmp, np->mcolor);
78			dtmp = ldot * omega * np->rdiff / PI;
79			scalecolor(ctmp, dtmp);
80			addcolor(cval, ctmp);
81			}
82			if (ldot > FTINY && np->rspec > FTINY && np->alpha2 > FTINY) {
83			/*
84			* Compute specular reflection coefficient using
85			* gaussian distribution model.
86			*/
87			/* roughness + source */
88			dtmp = np->alpha2 + omega/(2.0*PI);
89			/* gaussian */
90			dtmp = exp((DOT(np->vrefl,ldir)-1.)/dtmp)/(2.*PI)/dtmp;
91			/* worth using? */
92			if (dtmp > FTINY) {
93			copycolor(ctmp, np->scolor);
94	greg	1.13	dtmp *= omega / np->pdot;
95	greg	1.3	scalecolor(ctmp, dtmp);
96			addcolor(cval, ctmp);
97			}
98			}
99			if (ldot < -FTINY && np->tdiff > FTINY) {
100			/*
101			* Compute diffuse transmission.
102			*/
103			copycolor(ctmp, np->mcolor);
104			dtmp = -ldot * omega * np->tdiff / PI;
105			scalecolor(ctmp, dtmp);
106			addcolor(cval, ctmp);
107			}
108			if (ldot < -FTINY && np->tspec > FTINY && np->alpha2 > FTINY) {
109			/*
110	greg	1.4	* Compute specular transmission. Specular transmission
111	greg	1.13	* is always modified by material color.
112	greg	1.3	*/
113			/* roughness + source */
114			dtmp = np->alpha2 + omega/(2.0*PI);
115			/* gaussian */
116			dtmp = exp((DOT(np->pr->rdir,ldir)-1.)/dtmp)/(2.*PI)/dtmp;
117			/* worth using? */
118			if (dtmp > FTINY) {
119	greg	1.13	copycolor(ctmp, np->mcolor);
120			dtmp = np->tspec omega / np->pdot;
121			scalecolor(ctmp, dtmp);
122	greg	1.3	addcolor(cval, ctmp);
123			}
124			}
125			}
126
127
128			m_normal(m, r) /* color a ray which hit something normal */
129			register OBJREC *m;
130			register RAY *r;
131			{
132			NORMDAT nd;
133	greg	1.9	double transtest, transdist;
134	greg	1.1	double dtmp;
135			COLOR ctmp;
136			register int i;
137
138			if (m->oargs.nfargs != (m->otype == MAT_TRANS ? 7 : 5))
139			objerror(m, USER, "bad # arguments");
140			/* easy shadow test */
141			if (r->crtype & SHADOW && m->otype != MAT_TRANS)
142			return;
143	greg	1.3	nd.mp = m;
144			nd.pr = r;
145	greg	1.1	/* get material color */
146	greg	1.3	setcolor(nd.mcolor, m->oargs.farg[0],
147	greg	1.1	m->oargs.farg[1],
148			m->oargs.farg[2]);
149			/* get roughness */
150	greg	1.3	nd.alpha2 = m->oargs.farg[4];
151			nd.alpha2 = 2.0 nd.alpha2;
152	greg	1.1	/* reorient if necessary */
153			if (r->rod < 0.0)
154			flipsurface(r);
155			/* get modifiers */
156			raytexture(r, m->omod);
157	greg	1.3	nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */
158	greg	1.13	if (nd.pdot < .001)
159			nd.pdot = .001; /* non-zero for dirnorm() */
160	greg	1.3	multcolor(nd.mcolor, r->pcol); /* modify material color */
161	greg	1.9	transtest = 0;
162	greg	1.1	/* get specular component */
163	greg	1.3	nd.rspec = m->oargs.farg[3];
164	greg	1.1
165	greg	1.3	if (nd.rspec > FTINY) { /* has specular component */
166	greg	1.1	/* compute specular color */
167			if (m->otype == MAT_METAL)
168	greg	1.3	copycolor(nd.scolor, nd.mcolor);
169	greg	1.1	else
170	greg	1.3	setcolor(nd.scolor, 1.0, 1.0, 1.0);
171			scalecolor(nd.scolor, nd.rspec);
172	greg	1.1	/* improved model */
173	greg	1.3	dtmp = exp(-BSPEC(m)*nd.pdot);
174	greg	1.1	for (i = 0; i < 3; i++)
175	greg	1.3	colval(nd.scolor,i) += (1.0-colval(nd.scolor,i))*dtmp;
176			nd.rspec += (1.0-nd.rspec)*dtmp;
177	greg	1.1	/* compute reflected ray */
178			for (i = 0; i < 3; i++)
179	greg	1.3	nd.vrefl[i] = r->rdir[i] + 2.0nd.pdotnd.pnorm[i];
180	greg	1.1
181	greg	1.3	if (nd.alpha2 <= FTINY && !(r->crtype & SHADOW)) {
182			RAY lr;
183			if (rayorigin(&lr, r, REFLECTED, nd.rspec) == 0) {
184			VCOPY(lr.rdir, nd.vrefl);
185	greg	1.1	rayvalue(&lr);
186	greg	1.3	multcolor(lr.rcol, nd.scolor);
187	greg	1.1	addcolor(r->rcol, lr.rcol);
188			}
189	greg	1.3	}
190	greg	1.1	}
191	greg	1.3	/* compute transmission */
192	greg	1.1	if (m->otype == MAT_TRANS) {
193	greg	1.3	nd.trans = m->oargs.farg[5]*(1.0 - nd.rspec);
194			nd.tspec = nd.trans * m->oargs.farg[6];
195			nd.tdiff = nd.trans - nd.tspec;
196	greg	1.1	} else
197	greg	1.3	nd.tdiff = nd.tspec = nd.trans = 0.0;
198	greg	1.1	/* transmitted ray */
199	greg	1.3	if (nd.tspec > FTINY && nd.alpha2 <= FTINY) {
200			RAY lr;
201			if (rayorigin(&lr, r, TRANS, nd.tspec) == 0) {
202	greg	1.12	if (!(r->crtype & SHADOW) &&
203			DOT(r->pert,r->pert) > FTINY*FTINY) {
204	greg	1.9	for (i = 0; i < 3; i++) /* perturb direction */
205			lr.rdir[i] = r->rdir[i] -
206			.75*r->pert[i];
207			normalize(lr.rdir);
208	greg	1.10	} else {
209			VCOPY(lr.rdir, r->rdir);
210	greg	1.9	transtest = 2;
211	greg	1.10	}
212	greg	1.1	rayvalue(&lr);
213	greg	1.3	scalecolor(lr.rcol, nd.tspec);
214	greg	1.8	multcolor(lr.rcol, nd.mcolor); /* modified by color */
215	greg	1.1	addcolor(r->rcol, lr.rcol);
216	greg	1.9	transtest *= bright(lr.rcol);
217			transdist = r->rot + lr.rt;
218	greg	1.1	}
219	greg	1.3	}
220	greg	1.1	if (r->crtype & SHADOW) /* the rest is shadow */
221			return;
222			/* diffuse reflection */
223	greg	1.3	nd.rdiff = 1.0 - nd.trans - nd.rspec;
224	greg	1.1
225	greg	1.3	if (nd.rdiff <= FTINY && nd.tdiff <= FTINY && nd.alpha2 <= FTINY)
226	greg	1.1	return; /* purely specular */
227
228	greg	1.3	if (nd.rdiff > FTINY) { /* ambient from this side */
229	greg	1.2	ambient(ctmp, r);
230	greg	1.3	if (nd.alpha2 <= FTINY)
231			scalecolor(ctmp, nd.rdiff);
232	greg	1.2	else
233	greg	1.3	scalecolor(ctmp, 1.0-nd.trans);
234			multcolor(ctmp, nd.mcolor); /* modified by material color */
235	greg	1.2	addcolor(r->rcol, ctmp); /* add to returned color */
236			}
237	greg	1.3	if (nd.tdiff > FTINY) { /* ambient from other side */
238	greg	1.1	flipsurface(r);
239	greg	1.2	ambient(ctmp, r);
240	greg	1.3	if (nd.alpha2 <= FTINY)
241			scalecolor(ctmp, nd.tdiff);
242	greg	1.2	else
243	greg	1.3	scalecolor(ctmp, nd.trans);
244	greg	1.13	multcolor(ctmp, nd.mcolor); /* modified by color */
245	greg	1.1	addcolor(r->rcol, ctmp);
246			flipsurface(r);
247			}
248	greg	1.3	/* add direct component */
249			direct(r, dirnorm, &nd);
250	greg	1.9	/* check distance */
251			if (transtest > bright(r->rcol))
252			r->rt = transdist;
253	greg	1.1	}