src/rt/normal.c

/* Copyright (c) 1986 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  "source.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 */


m_normal(m, r)                  /* color a ray which hit something normal */
register OBJREC  *m;
register RAY  *r;
{
        double  exp();
        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 */
        RAY  lr;                /* ray to illumination source */
        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 */
        double  ldot;
        double  omega;
        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;
                                                /* get material color */
        setcolor(mcolor, m->oargs.farg[0],
                           m->oargs.farg[1],
                           m->oargs.farg[2]);
                                                /* get roughness */
        alpha2 = m->oargs.farg[4];
        alpha2 *= 2.0 * alpha2;
                                                /* reorient if necessary */
        if (r->rod < 0.0)
                flipsurface(r);
                                                /* get modifiers */
        raytexture(r, m->omod);
        pdot = raynormal(pnorm, r);             /* perturb normal */
        multcolor(mcolor, r->pcol);             /* modify material color */
                                                /* get specular component */
        rspec = m->oargs.farg[3];

        if (rspec > FTINY) {                    /* has specular component */
                                                /* compute specular color */
                if (m->otype == MAT_METAL)
                        copycolor(scolor, mcolor);
                else
                        setcolor(scolor, 1.0, 1.0, 1.0);
                scalecolor(scolor, rspec);
                                                /* improved model */
                dtmp = exp(-BSPEC(m)*pdot);
                for (i = 0; i < 3; i++)
                        colval(scolor,i) += (1.0-colval(scolor,i))*dtmp;
                rspec += (1.0-rspec)*dtmp;
                                                /* compute reflected ray */
                for (i = 0; i < 3; i++)
                        vrefl[i] = r->rdir[i] + 2.0*pdot*pnorm[i];

                if (alpha2 <= FTINY && !(r->crtype & SHADOW))
                        if (rayorigin(&lr, r, REFLECTED, rspec) == 0) {
                                VCOPY(lr.rdir, vrefl);
                                rayvalue(&lr);
                                multcolor(lr.rcol, scolor);
                                addcolor(r->rcol, lr.rcol);
                        }
        }

        if (m->otype == MAT_TRANS) {
                trans = m->oargs.farg[5]*(1.0 - rspec);
                tspec = trans * m->oargs.farg[6];
                tdiff = trans - tspec;
        } else
                tdiff = tspec = trans = 0.0;
                                                /* transmitted ray */
        if (tspec > FTINY && alpha2 <= FTINY)
                if (rayorigin(&lr, r, TRANS, tspec) == 0) {
                        VCOPY(lr.rdir, r->rdir);
                        rayvalue(&lr);
                        scalecolor(lr.rcol, tspec);
                        addcolor(r->rcol, lr.rcol);
                }
        if (r->crtype & SHADOW)                 /* the rest is shadow */
                return;
                                                /* diffuse reflection */
        rdiff = 1.0 - trans - rspec;

        if (rdiff <= FTINY && tdiff <= FTINY && alpha2 <= FTINY)
                return;                         /* purely specular */

        if (rdiff > FTINY) {            /* ambient from this side */
                ambient(ctmp, r);
                if (alpha2 <= FTINY)
                        scalecolor(ctmp, rdiff);
                else
                        scalecolor(ctmp, 1.0-trans);
                multcolor(ctmp, mcolor);        /* modified by material color */
                addcolor(r->rcol, ctmp);        /* add to returned color */
        }
        if (tdiff > FTINY) {            /* ambient from other side */
                flipsurface(r);
                ambient(ctmp, r);
                if (alpha2 <= FTINY)
                        scalecolor(ctmp, tdiff);
                else
                        scalecolor(ctmp, trans);
                multcolor(ctmp, mcolor);
                addcolor(r->rcol, ctmp);
                flipsurface(r);
        }
        
        for (i = 0; i < nsources; i++) {        /* add specular and diffuse */

                if ((omega = srcray(&lr, r, i)) == 0.0)
                        continue;               /* bad source */

                ldot = DOT(pnorm, lr.rdir);
        
                if (ldot < 0.0 ? trans <= FTINY : trans >= 1.0-FTINY)
                        continue;               /* wrong side */
        
                rayvalue(&lr);                  /* compute light ray value */
        
                if (intens(lr.rcol) <= FTINY)
                        continue;               /* didn't hit light source */

                if (ldot > FTINY && rdiff > FTINY) {
                        /*
                         *  Compute and add diffuse component to returned color.
                         *  The diffuse component will always be modified by the
                         *  color of the material.
                         */
                        copycolor(ctmp, lr.rcol);
                        dtmp = ldot * omega * rdiff / PI;
                        scalecolor(ctmp, dtmp);
                        multcolor(ctmp, mcolor);
                        addcolor(r->rcol, ctmp);
                }
                if (ldot > FTINY && rspec > FTINY && alpha2 > FTINY) {
                        /*
                         *  Compute specular reflection coefficient using
                         *  gaussian distribution model.
                         */
                                                        /* roughness + source */
                        dtmp = alpha2 + omega/(2.0*PI);
                                                        /* gaussian */
                        dtmp = exp((DOT(vrefl,lr.rdir)-1.)/dtmp)/(2.*PI)/dtmp;
                                                        /* worth using? */
                        if (dtmp > FTINY) {
                                copycolor(ctmp, lr.rcol);
                                dtmp *= omega;
                                scalecolor(ctmp, dtmp);
                                multcolor(ctmp, scolor);
                                addcolor(r->rcol, ctmp);
                        }
                }
                if (ldot < -FTINY && tdiff > FTINY) {
                        /*
                         *  Compute diffuse transmission.
                         */
                        copycolor(ctmp, lr.rcol);
                        dtmp = -ldot * omega * tdiff / PI;
                        scalecolor(ctmp, dtmp);
                        multcolor(ctmp, mcolor);
                        addcolor(r->rcol, ctmp);
                }
                if (ldot < -FTINY && tspec > FTINY && alpha2 > FTINY) {
                        /*
                         *  Compute specular transmission.
                         */
                                                        /* roughness + source */
                        dtmp = alpha2 + omega/(2.0*PI);
                                                        /* gaussian */
                        dtmp = exp((DOT(r->rdir,lr.rdir)-1.)/dtmp)/(2.*PI)/dtmp;
                                                        /* worth using? */
                        if (dtmp > FTINY) {
                                copycolor(ctmp, lr.rcol);
                                dtmp *= tspec * omega;
                                scalecolor(ctmp, dtmp);
                                addcolor(r->rcol, ctmp);
                        }
                }
        }
}
Revision:	1.2
Committed:	Sat Apr 15 12:23:22 1989 UTC (35 years ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.1:	+15 -7 lines
Log Message:	repaired and improved ambient calculation
#	User	Rev	Content
1	greg	1.1	/* Copyright (c) 1986 Regents of the University of California */
2
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 "source.h"
19
20			#include "otypes.h"
21
22			/*
23			* This routine uses portions of the reflection
24			* model described by Cook and Torrance.
25			* The computation of specular components has been simplified by
26			* numerous approximations and ommisions to improve speed.
27			* 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_PLASTIC and MAT_METAL are:
31			* red grn blu specular-frac. facet-slope
32			*
33			* Arguments for MAT_TRANS are:
34			* red grn blu rspec rough trans tspec
35			*/
36
37			#define BSPEC(m) (6.0) /* specularity parameter b */
38
39
40			m_normal(m, r) /* color a ray which hit something normal */
41			register OBJREC *m;
42			register RAY *r;
43			{
44			double exp();
45			COLOR mcolor; /* color of this material */
46			COLOR scolor; /* color of specular component */
47			FVECT vrefl; /* vector in direction of reflected ray */
48			double alpha2; /* roughness squared times 2 */
49			RAY lr; /* ray to illumination source */
50			double rdiff, rspec; /* reflected specular, diffuse */
51			double trans; /* transmissivity */
52			double tdiff, tspec; /* transmitted specular, diffuse */
53			FVECT pnorm; /* perturbed surface normal */
54			double pdot; /* perturbed dot product */
55			double ldot;
56			double omega;
57			double dtmp;
58			COLOR ctmp;
59			register int i;
60
61			if (m->oargs.nfargs != (m->otype == MAT_TRANS ? 7 : 5))
62			objerror(m, USER, "bad # arguments");
63			/* easy shadow test */
64			if (r->crtype & SHADOW && m->otype != MAT_TRANS)
65			return;
66			/* get material color */
67			setcolor(mcolor, m->oargs.farg[0],
68			m->oargs.farg[1],
69			m->oargs.farg[2]);
70			/* get roughness */
71			alpha2 = m->oargs.farg[4];
72			alpha2 = 2.0 alpha2;
73			/* reorient if necessary */
74			if (r->rod < 0.0)
75			flipsurface(r);
76			/* get modifiers */
77			raytexture(r, m->omod);
78			pdot = raynormal(pnorm, r); /* perturb normal */
79			multcolor(mcolor, r->pcol); /* modify material color */
80			/* get specular component */
81			rspec = m->oargs.farg[3];
82
83			if (rspec > FTINY) { /* has specular component */
84			/* compute specular color */
85			if (m->otype == MAT_METAL)
86			copycolor(scolor, mcolor);
87			else
88			setcolor(scolor, 1.0, 1.0, 1.0);
89			scalecolor(scolor, rspec);
90			/* improved model */
91			dtmp = exp(-BSPEC(m)*pdot);
92			for (i = 0; i < 3; i++)
93			colval(scolor,i) += (1.0-colval(scolor,i))*dtmp;
94			rspec += (1.0-rspec)*dtmp;
95			/* compute reflected ray */
96			for (i = 0; i < 3; i++)
97			vrefl[i] = r->rdir[i] + 2.0pdotpnorm[i];
98
99			if (alpha2 <= FTINY && !(r->crtype & SHADOW))
100			if (rayorigin(&lr, r, REFLECTED, rspec) == 0) {
101			VCOPY(lr.rdir, vrefl);
102			rayvalue(&lr);
103			multcolor(lr.rcol, scolor);
104			addcolor(r->rcol, lr.rcol);
105			}
106			}
107
108			if (m->otype == MAT_TRANS) {
109			trans = m->oargs.farg[5]*(1.0 - rspec);
110			tspec = trans * m->oargs.farg[6];
111			tdiff = trans - tspec;
112			} else
113			tdiff = tspec = trans = 0.0;
114			/* transmitted ray */
115			if (tspec > FTINY && alpha2 <= FTINY)
116			if (rayorigin(&lr, r, TRANS, tspec) == 0) {
117			VCOPY(lr.rdir, r->rdir);
118			rayvalue(&lr);
119			scalecolor(lr.rcol, tspec);
120			addcolor(r->rcol, lr.rcol);
121			}
122			if (r->crtype & SHADOW) /* the rest is shadow */
123			return;
124			/* diffuse reflection */
125			rdiff = 1.0 - trans - rspec;
126
127			if (rdiff <= FTINY && tdiff <= FTINY && alpha2 <= FTINY)
128			return; /* purely specular */
129
130	greg	1.2	if (rdiff > FTINY) { /* ambient from this side */
131			ambient(ctmp, r);
132			if (alpha2 <= FTINY)
133			scalecolor(ctmp, rdiff);
134			else
135			scalecolor(ctmp, 1.0-trans);
136			multcolor(ctmp, mcolor); /* modified by material color */
137			addcolor(r->rcol, ctmp); /* add to returned color */
138			}
139			if (tdiff > FTINY) { /* ambient from other side */
140	greg	1.1	flipsurface(r);
141	greg	1.2	ambient(ctmp, r);
142			if (alpha2 <= FTINY)
143			scalecolor(ctmp, tdiff);
144			else
145			scalecolor(ctmp, trans);
146	greg	1.1	multcolor(ctmp, mcolor);
147			addcolor(r->rcol, ctmp);
148			flipsurface(r);
149			}
150
151			for (i = 0; i < nsources; i++) { /* add specular and diffuse */
152
153			if ((omega = srcray(&lr, r, i)) == 0.0)
154			continue; /* bad source */
155
156			ldot = DOT(pnorm, lr.rdir);
157
158			if (ldot < 0.0 ? trans <= FTINY : trans >= 1.0-FTINY)
159			continue; /* wrong side */
160
161			rayvalue(&lr); /* compute light ray value */
162
163			if (intens(lr.rcol) <= FTINY)
164			continue; /* didn't hit light source */
165
166			if (ldot > FTINY && rdiff > FTINY) {
167			/*
168			* Compute and add diffuse component to returned color.
169			* The diffuse component will always be modified by the
170			* color of the material.
171			*/
172			copycolor(ctmp, lr.rcol);
173			dtmp = ldot * omega * rdiff / PI;
174			scalecolor(ctmp, dtmp);
175			multcolor(ctmp, mcolor);
176			addcolor(r->rcol, ctmp);
177			}
178			if (ldot > FTINY && rspec > FTINY && alpha2 > FTINY) {
179			/*
180			* Compute specular reflection coefficient using
181			* gaussian distribution model.
182			*/
183			/* roughness + source */
184			dtmp = alpha2 + omega/(2.0*PI);
185			/* gaussian */
186			dtmp = exp((DOT(vrefl,lr.rdir)-1.)/dtmp)/(2.*PI)/dtmp;
187			/* worth using? */
188			if (dtmp > FTINY) {
189			copycolor(ctmp, lr.rcol);
190			dtmp *= omega;
191			scalecolor(ctmp, dtmp);
192			multcolor(ctmp, scolor);
193			addcolor(r->rcol, ctmp);
194			}
195			}
196			if (ldot < -FTINY && tdiff > FTINY) {
197			/*
198			* Compute diffuse transmission.
199			*/
200			copycolor(ctmp, lr.rcol);
201			dtmp = -ldot * omega * tdiff / PI;
202			scalecolor(ctmp, dtmp);
203			multcolor(ctmp, mcolor);
204			addcolor(r->rcol, ctmp);
205			}
206			if (ldot < -FTINY && tspec > FTINY && alpha2 > FTINY) {
207			/*
208			* Compute specular transmission.
209			*/
210			/* roughness + source */
211			dtmp = alpha2 + omega/(2.0*PI);
212			/* gaussian */
213			dtmp = exp((DOT(r->rdir,lr.rdir)-1.)/dtmp)/(2.*PI)/dtmp;
214			/* worth using? */
215			if (dtmp > FTINY) {
216			copycolor(ctmp, lr.rcol);
217			dtmp = tspec omega;
218			scalecolor(ctmp, dtmp);
219			addcolor(r->rcol, ctmp);
220			}
221			}
222			}
223			}