src/rt/source.c

/* Copyright (c) 1986 Regents of the University of California */

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

/*
 *  source.c - routines dealing with illumination sources.
 *
 *     8/20/85
 */

#include  "ray.h"

#include  "octree.h"

#include  "source.h"

#include  "otypes.h"

#include  "cone.h"

#include  "face.h"

#include  "random.h"


extern double  dstrsrc;                 /* source distribution amount */
extern double  shadthresh;              /* relative shadow threshold */
extern double  shadcert;                /* shadow testing certainty */

SRCREC  *source = NULL;                 /* our list of sources */
int  nsources = 0;                      /* the number of sources */


marksources()                   /* find and mark source objects */
{
        register OBJREC  *o, *m;
        register int  i;

        for (i = 0; i < nobjects; i++) {
        
                o = objptr(i);

                if (o->omod == OVOID)
                        continue;

                m = objptr(o->omod);

                if (m->otype != MAT_LIGHT &&
                                m->otype != MAT_ILLUM &&
                                m->otype != MAT_GLOW &&
                                m->otype != MAT_SPOT)
                        continue;
        
                if (m->oargs.nfargs != (m->otype == MAT_GLOW ? 4 :
                                m->otype == MAT_SPOT ? 7 : 3))
                        objerror(m, USER, "bad # arguments");

                if (m->otype == MAT_GLOW &&
                                o->otype != OBJ_SOURCE &&
                                m->oargs.farg[3] <= FTINY)
                        continue;                       /* don't bother */

                if (source == NULL)
                        source = (SRCREC *)malloc(sizeof(SRCREC));
                else
                        source = (SRCREC *)realloc((char *)source,
                                        (unsigned)(nsources+1)*sizeof(SRCREC));
                if (source == NULL)
                        error(SYSTEM, "out of memory in marksources");

                newsource(&source[nsources], o);

                if (m->otype == MAT_GLOW) {
                        source[nsources].sflags |= SPROX;
                        source[nsources].sl.prox = m->oargs.farg[3];
                        if (o->otype == OBJ_SOURCE)
                                source[nsources].sflags |= SSKIP;
                } else if (m->otype == MAT_SPOT) {
                        source[nsources].sflags |= SSPOT;
                        source[nsources].sl.s = makespot(m);
                }
                nsources++;
        }
}


newsource(src, so)                      /* add a source to the array */
register SRCREC  *src;
register OBJREC  *so;
{
        double  cos(), tan(), sqrt();
        double  theta;
        FACE  *f;
        CONE  *co;
        int  j;
        register int  i;
        
        src->sflags = 0;
        src->nhits = 1; src->ntests = 2;        /* start probability = 1/2 */
        src->so = so;

        switch (so->otype) {
        case OBJ_SOURCE:
                if (so->oargs.nfargs != 4)
                        objerror(so, USER, "bad arguments");
                src->sflags |= SDISTANT;
                VCOPY(src->sloc, so->oargs.farg);
                if (normalize(src->sloc) == 0.0)
                        objerror(so, USER, "zero direction");
                theta = PI/180.0/2.0 * so->oargs.farg[3];
                if (theta <= FTINY)
                        objerror(so, USER, "zero size");
                src->ss = theta >= PI/4 ? 1.0 : tan(theta);
                src->ss2 = 2.0*PI * (1.0 - cos(theta));
                break;
        case OBJ_SPHERE:
                VCOPY(src->sloc, so->oargs.farg);
                src->ss = so->oargs.farg[3];
                src->ss2 = PI * src->ss * src->ss;
                break;
        case OBJ_FACE:
                                                /* get the face */
                f = getface(so);
                                                /* find the center */
                for (j = 0; j < 3; j++) {
                        src->sloc[j] = 0.0;
                        for (i = 0; i < f->nv; i++)
                                src->sloc[j] += VERTEX(f,i)[j];
                        src->sloc[j] /= f->nv;
                }
                if (!inface(src->sloc, f))
                        objerror(so, USER, "cannot hit center");
                src->ss = sqrt(f->area / PI);
                src->ss2 = f->area;
                break;
        case OBJ_RING:
                                                /* get the ring */
                co = getcone(so, 0);
                VCOPY(src->sloc, CO_P0(co));
                if (CO_R0(co) > 0.0)
                        objerror(so, USER, "cannot hit center");
                src->ss = CO_R1(co);
                src->ss2 = PI * src->ss * src->ss;
                break;
        default:
                objerror(so, USER, "illegal material");
        }
}


SPOT *
makespot(m)                     /* make a spotlight */
register OBJREC  *m;
{
        extern double  cos();
        register SPOT  *ns;

        if ((ns = (SPOT *)malloc(sizeof(SPOT))) == NULL)
                error(SYSTEM, "out of memory in makespot");
        ns->siz = 2.0*PI * (1.0 - cos(PI/180.0/2.0 * m->oargs.farg[3]));
        VCOPY(ns->aim, m->oargs.farg+4);
        if ((ns->flen = normalize(ns->aim)) == 0.0)
                objerror(m, USER, "zero focus vector");
        return(ns);
}


double
srcray(sr, r, sn)               /* send a ray to a source, return domega */
register RAY  *sr;              /* returned source ray */
RAY  *r;                        /* ray which hit object */
register int  sn;               /* source number */
{
        register double  *norm = NULL;  /* plane normal */
        double  ddot;                   /* (distance times) cosine */
        FVECT  vd;
        double  d;
        register int  i;

        if (source[sn].sflags & SSKIP)
                return(0.0);                    /* skip this source */

        rayorigin(sr, r, SHADOW, 1.0);          /* ignore limits */

        sr->rsrc = sn;                          /* remember source */
                                                /* get source direction */
        if (source[sn].sflags & SDISTANT)
                                                /* constant direction */
                VCOPY(sr->rdir, source[sn].sloc);
        else {                                  /* compute direction */
                for (i = 0; i < 3; i++)
                        sr->rdir[i] = source[sn].sloc[i] - sr->rorg[i];

                if (source[sn].so->otype == OBJ_FACE)
                        norm = getface(source[sn].so)->norm;
                else if (source[sn].so->otype == OBJ_RING)
                        norm = getcone(source[sn].so,0)->ad;

                if (norm != NULL && (ddot = -DOT(sr->rdir, norm)) <= FTINY)
                        return(0.0);            /* behind surface! */
        }
        if (dstrsrc > FTINY) {
                                        /* distribute source direction */
                for (i = 0; i < 3; i++)
                        vd[i] = dstrsrc * source[sn].ss * (1.0 - 2.0*frandom());

                if (norm != NULL) {             /* project offset */
                        d = DOT(vd, norm);
                        for (i = 0; i < 3; i++)
                                vd[i] -= d * norm[i];
                }
                for (i = 0; i < 3; i++)         /* offset source direction */
                        sr->rdir[i] += vd[i];

        } else if (source[sn].sflags & SDISTANT)
                                                /* already normalized */
                return(source[sn].ss2);

        if ((d = normalize(sr->rdir)) == 0.0)
                                                /* at source! */
                return(0.0);
        
        if (source[sn].sflags & SDISTANT)
                                                /* domega constant */
                return(source[sn].ss2);

        else {
                                                /* check proximity */
                if (source[sn].sflags & SPROX &&
                                d > source[sn].sl.prox)
                        return(0.0);

                if (norm != NULL)
                        ddot /= d;
                else
                        ddot = 1.0;
                                                /* check angle */
                if (source[sn].sflags & SSPOT) {
                        if (source[sn].sl.s->siz < 2.0*PI *
                                (1.0 + DOT(source[sn].sl.s->aim,sr->rdir)))
                                return(0.0);
                        d += source[sn].sl.s->flen;
                }
                                                /* return domega */
                return(ddot*source[sn].ss2/(d*d));
        }
}


sourcehit(r)                    /* check to see if ray hit distant source */
register RAY  *r;
{
        int  first, last;
        register int  i;

        if (r->rsrc >= 0) {             /* check only one if aimed */
                first = last = r->rsrc;
        } else {                        /* otherwise check all */
                first = 0; last = nsources-1;
        }
        for (i = first; i <= last; i++)
                if (source[i].sflags & SDISTANT)
                        /*
                         * Check to see if ray is within
                         * solid angle of source.
                         */
                        if (2.0*PI * (1.0 - DOT(source[i].sloc,r->rdir))
                                        <= source[i].ss2) {
                                r->ro = source[i].so;
                                if (!(source[i].sflags & SSKIP))
                                        break;
                        }

        if (r->ro != NULL) {
                for (i = 0; i < 3; i++)
                        r->ron[i] = -r->rdir[i];
                r->rod = 1.0;
                r->rofs = 1.0; setident4(r->rofx);
                r->robs = 1.0; setident4(r->robx);
                return(1);
        }
        return(0);
}


static int
cntcmp(sc1, sc2)                        /* contribution compare (descending) */
register CNTPTR  *sc1, *sc2;
{
        if (sc1->brt > sc2->brt)
                return(-1);
        if (sc1->brt < sc2->brt)
                return(1);
        return(0);
}


direct(r, f, p)                         /* add direct component */
RAY  *r;                        /* ray that hit surface */
int  (*f)();                    /* direct component coefficient function */
char  *p;                       /* data for f */
{
        extern double  pow();
        register int  sn;
        register CONTRIB  *srccnt;
        register CNTPTR  *cntord;
        int  nshadcheck, ncnts;
        double  prob, ourthresh, hwt, test2, hit2;
        RAY  sr;

        srccnt = (CONTRIB *)malloc(nsources*sizeof(CONTRIB));
        cntord = (CNTPTR *)malloc(nsources*sizeof(CNTPTR));
        if (srccnt == NULL || cntord == NULL)
                error(SYSTEM, "out of memory in direct");
                                                /* compute number to check */
        nshadcheck = pow((double)nsources, shadcert) + .5;
                                                /* modify threshold */
        ourthresh = shadthresh / r->rweight;
                                                /* potential contributions */
        for (sn = 0; sn < nsources; sn++) {
                cntord[sn].sno = sn;
                cntord[sn].brt = 0.0;
                                                /* get source ray */
                if ((srccnt[sn].dom = srcray(&sr, r, sn)) == 0.0)
                        continue;
                VCOPY(srccnt[sn].dir, sr.rdir);
                                                /* compute coefficient */
                (*f)(srccnt[sn].val, p, srccnt[sn].dir, srccnt[sn].dom);
                cntord[sn].brt = bright(srccnt[sn].val);
                if (cntord[sn].brt <= 0.0)
                        continue;
                                                /* compute intersection */
                if (!( source[sn].sflags & SDISTANT ?
                                sourcehit(&sr) :
                                (*ofun[source[sn].so->otype].funp)
                                (source[sn].so, &sr) ))
                        continue;
                                                /* compute contribution */
                rayshade(&sr, sr.ro->omod);
                multcolor(srccnt[sn].val, sr.rcol);
                cntord[sn].brt = bright(srccnt[sn].val);
        }
                                                /* sort contributions */
        qsort(cntord, nsources, sizeof(CNTPTR), cntcmp);
        {                                       /* find last */
                register int  l, m;

                sn = 0; ncnts = l = nsources;
                while ((m = (sn + ncnts) >> 1) != l) {
                        if (cntord[m].brt > 0.0)
                                sn = m;
                        else
                                ncnts = m;
                        l = m;
                }
        }
                                                /* accumulate tail */
        for (sn = ncnts-1; sn > 0; sn--)
                cntord[sn-1].brt += cntord[sn].brt;
                                                /* start with prob=.5 */
        hit2 = 0.5; test2 = 1.0;
                                                /* test for shadows */
        for (sn = 0; sn < ncnts; sn++) {
                                                /* check threshold */
                if ((sn+nshadcheck>=ncnts ? cntord[sn].brt :
                                cntord[sn].brt-cntord[sn+nshadcheck].brt) <
                                ourthresh*bright(r->rcol))
                        break;
                                                /* get statistics */
                hwt = (double)source[cntord[sn].sno].nhits /
                                (double)source[cntord[sn].sno].ntests;
                test2 += hwt;
                source[cntord[sn].sno].ntests++;
                                                /* test for hit */
                rayorigin(&sr, r, SHADOW, 1.0);
                VCOPY(sr.rdir, srccnt[cntord[sn].sno].dir);
                if (localhit(&sr, &thescene) &&
                                sr.ro != source[cntord[sn].sno].so) {
                                                /* check for transmission */
                        rayshade(&sr, sr.ro->omod);
                        if (bright(sr.rcol) <= FTINY)
                                continue;       /* missed! */
                        (*f)(srccnt[cntord[sn].sno].val, p,
                                        srccnt[cntord[sn].sno].dir,
                                        srccnt[cntord[sn].sno].dom);
                        multcolor(srccnt[cntord[sn].sno].val, sr.rcol);
                }
                                                /* add contribution if hit */
                addcolor(r->rcol, srccnt[cntord[sn].sno].val);
                hit2 += hwt;
                source[cntord[sn].sno].nhits++;
        }
                                        /* weighted hit rate */
        hwt = hit2 / test2;
#ifdef DEBUG
        sprintf(errmsg, "%d tested, %d untested, %f hit rate\n",
                        sn, ncnts-sn, hwt);
        eputs(errmsg);
#endif
                                        /* add in untested sources */
        for ( ; sn < ncnts; sn++) {
                prob = hwt * (double)source[cntord[sn].sno].nhits /
                                (double)source[cntord[sn].sno].ntests;
                scalecolor(srccnt[cntord[sn].sno].val, prob);
                addcolor(r->rcol, srccnt[cntord[sn].sno].val);
        }
                
        free(srccnt);
        free(cntord);
}


#define  wrongsource(m, r)      (m->otype!=MAT_ILLUM && \
                                r->rsrc>=0 && \
                                source[r->rsrc].so!=r->ro)

#define  badambient(m, r)       ((r->crtype&(AMBIENT|SHADOW))==AMBIENT && \
                                !(r->rtype&REFLECTED) &&        /* hack! */\
                                !(m->otype==MAT_GLOW&&r->rot>m->oargs.farg[3]))

#define  passillum(m, r)        (m->otype==MAT_ILLUM && \
                                !(r->rsrc>=0&&source[r->rsrc].so==r->ro))


m_light(m, r)                   /* ray hit a light source */
register OBJREC  *m;
register RAY  *r;
{
                                                /* check for behind */
        if (r->rod < 0.0)
                return;
                                                /* check for over-counting */
        if (wrongsource(m, r) || badambient(m, r))
                return;
                                                /* check for passed illum */
        if (passillum(m, r)) {

                if (m->oargs.nsargs < 1 || !strcmp(m->oargs.sarg[0], VOIDID))
                        raytrans(r);
                else
                        rayshade(r, modifier(m->oargs.sarg[0]));

                                                /* otherwise treat as source */
        } else {
                                                /* get distribution pattern */
                raytexture(r, m->omod);
                                                /* get source color */
                setcolor(r->rcol, m->oargs.farg[0],
                                  m->oargs.farg[1],
                                  m->oargs.farg[2]);
                                                /* modify value */
                multcolor(r->rcol, r->pcol);
        }
}


o_source() {}           /* intersection with a source is done elsewhere */
Revision:	1.15
Committed:	Thu Jul 20 13:51:34 1989 UTC (36 years, 3 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.14:	+1 -1 lines
Log Message:	fixed bug in counting of small sources
#	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			* source.c - routines dealing with illumination sources.
9			*
10			* 8/20/85
11			*/
12
13			#include "ray.h"
14
15	greg	1.4	#include "octree.h"
16
17	greg	1.1	#include "source.h"
18
19			#include "otypes.h"
20
21			#include "cone.h"
22
23			#include "face.h"
24
25			#include "random.h"
26
27
28			extern double dstrsrc; /* source distribution amount */
29	greg	1.4	extern double shadthresh; /* relative shadow threshold */
30	greg	1.12	extern double shadcert; /* shadow testing certainty */
31	greg	1.1
32	greg	1.4	SRCREC source = NULL; / our list of sources */
33	greg	1.1	int nsources = 0; /* the number of sources */
34
35
36			marksources() /* find and mark source objects */
37			{
38			register OBJREC o, m;
39			register int i;
40
41			for (i = 0; i < nobjects; i++) {
42
43			o = objptr(i);
44
45			if (o->omod == OVOID)
46			continue;
47
48			m = objptr(o->omod);
49
50			if (m->otype != MAT_LIGHT &&
51			m->otype != MAT_ILLUM &&
52	greg	1.6	m->otype != MAT_GLOW &&
53			m->otype != MAT_SPOT)
54	greg	1.1	continue;
55
56	greg	1.6	if (m->oargs.nfargs != (m->otype == MAT_GLOW ? 4 :
57			m->otype == MAT_SPOT ? 7 : 3))
58	greg	1.1	objerror(m, USER, "bad # arguments");
59
60	greg	1.6	if (m->otype == MAT_GLOW &&
61			o->otype != OBJ_SOURCE &&
62			m->oargs.farg[3] <= FTINY)
63	greg	1.1	continue; /* don't bother */
64
65	greg	1.4	if (source == NULL)
66			source = (SRCREC *)malloc(sizeof(SRCREC));
67			else
68			source = (SRCREC )realloc((char )source,
69			(unsigned)(nsources+1)*sizeof(SRCREC));
70			if (source == NULL)
71			error(SYSTEM, "out of memory in marksources");
72	greg	1.1
73	greg	1.4	newsource(&source[nsources], o);
74	greg	1.1
75	greg	1.6	if (m->otype == MAT_GLOW) {
76			source[nsources].sflags \|= SPROX;
77			source[nsources].sl.prox = m->oargs.farg[3];
78			if (o->otype == OBJ_SOURCE)
79			source[nsources].sflags \|= SSKIP;
80			} else if (m->otype == MAT_SPOT) {
81			source[nsources].sflags \|= SSPOT;
82			source[nsources].sl.s = makespot(m);
83			}
84	greg	1.1	nsources++;
85			}
86			}
87
88
89			newsource(src, so) /* add a source to the array */
90	greg	1.4	register SRCREC *src;
91	greg	1.1	register OBJREC *so;
92			{
93			double cos(), tan(), sqrt();
94			double theta;
95			FACE *f;
96			CONE *co;
97			int j;
98			register int i;
99
100			src->sflags = 0;
101	greg	1.6	src->nhits = 1; src->ntests = 2; /* start probability = 1/2 */
102	greg	1.1	src->so = so;
103
104			switch (so->otype) {
105			case OBJ_SOURCE:
106			if (so->oargs.nfargs != 4)
107			objerror(so, USER, "bad arguments");
108			src->sflags \|= SDISTANT;
109			VCOPY(src->sloc, so->oargs.farg);
110			if (normalize(src->sloc) == 0.0)
111			objerror(so, USER, "zero direction");
112			theta = PI/180.0/2.0 * so->oargs.farg[3];
113			if (theta <= FTINY)
114			objerror(so, USER, "zero size");
115			src->ss = theta >= PI/4 ? 1.0 : tan(theta);
116			src->ss2 = 2.0PI (1.0 - cos(theta));
117			break;
118			case OBJ_SPHERE:
119			VCOPY(src->sloc, so->oargs.farg);
120			src->ss = so->oargs.farg[3];
121			src->ss2 = PI * src->ss * src->ss;
122			break;
123			case OBJ_FACE:
124			/* get the face */
125			f = getface(so);
126			/* find the center */
127			for (j = 0; j < 3; j++) {
128			src->sloc[j] = 0.0;
129			for (i = 0; i < f->nv; i++)
130			src->sloc[j] += VERTEX(f,i)[j];
131			src->sloc[j] /= f->nv;
132			}
133			if (!inface(src->sloc, f))
134			objerror(so, USER, "cannot hit center");
135			src->ss = sqrt(f->area / PI);
136			src->ss2 = f->area;
137			break;
138			case OBJ_RING:
139			/* get the ring */
140			co = getcone(so, 0);
141			VCOPY(src->sloc, CO_P0(co));
142			if (CO_R0(co) > 0.0)
143			objerror(so, USER, "cannot hit center");
144			src->ss = CO_R1(co);
145			src->ss2 = PI * src->ss * src->ss;
146			break;
147			default:
148			objerror(so, USER, "illegal material");
149			}
150			}
151
152
153	greg	1.6	SPOT *
154			makespot(m) /* make a spotlight */
155			register OBJREC *m;
156			{
157			extern double cos();
158			register SPOT *ns;
159
160			if ((ns = (SPOT *)malloc(sizeof(SPOT))) == NULL)
161			error(SYSTEM, "out of memory in makespot");
162			ns->siz = 2.0PI (1.0 - cos(PI/180.0/2.0 * m->oargs.farg[3]));
163			VCOPY(ns->aim, m->oargs.farg+4);
164			if ((ns->flen = normalize(ns->aim)) == 0.0)
165			objerror(m, USER, "zero focus vector");
166			return(ns);
167			}
168
169
170	greg	1.1	double
171			srcray(sr, r, sn) /* send a ray to a source, return domega */
172			register RAY sr; / returned source ray */
173			RAY r; / ray which hit object */
174			register int sn; /* source number */
175			{
176			register double norm = NULL; / plane normal */
177			double ddot; /* (distance times) cosine */
178			FVECT vd;
179			double d;
180			register int i;
181
182	greg	1.4	if (source[sn].sflags & SSKIP)
183	greg	1.1	return(0.0); /* skip this source */
184
185			rayorigin(sr, r, SHADOW, 1.0); /* ignore limits */
186
187			sr->rsrc = sn; /* remember source */
188			/* get source direction */
189	greg	1.4	if (source[sn].sflags & SDISTANT)
190	greg	1.1	/* constant direction */
191	greg	1.4	VCOPY(sr->rdir, source[sn].sloc);
192	greg	1.1	else { /* compute direction */
193			for (i = 0; i < 3; i++)
194	greg	1.4	sr->rdir[i] = source[sn].sloc[i] - sr->rorg[i];
195	greg	1.1
196	greg	1.4	if (source[sn].so->otype == OBJ_FACE)
197			norm = getface(source[sn].so)->norm;
198			else if (source[sn].so->otype == OBJ_RING)
199			norm = getcone(source[sn].so,0)->ad;
200	greg	1.1
201	greg	1.2	if (norm != NULL && (ddot = -DOT(sr->rdir, norm)) <= FTINY)
202	greg	1.1	return(0.0); /* behind surface! */
203			}
204			if (dstrsrc > FTINY) {
205			/* distribute source direction */
206			for (i = 0; i < 3; i++)
207	greg	1.4	vd[i] = dstrsrc * source[sn].ss * (1.0 - 2.0*frandom());
208	greg	1.1
209			if (norm != NULL) { /* project offset */
210			d = DOT(vd, norm);
211			for (i = 0; i < 3; i++)
212			vd[i] -= d * norm[i];
213			}
214			for (i = 0; i < 3; i++) /* offset source direction */
215			sr->rdir[i] += vd[i];
216
217	greg	1.4	} else if (source[sn].sflags & SDISTANT)
218	greg	1.1	/* already normalized */
219	greg	1.4	return(source[sn].ss2);
220	greg	1.1
221			if ((d = normalize(sr->rdir)) == 0.0)
222			/* at source! */
223			return(0.0);
224
225	greg	1.4	if (source[sn].sflags & SDISTANT)
226	greg	1.1	/* domega constant */
227	greg	1.4	return(source[sn].ss2);
228	greg	1.1
229			else {
230	greg	1.6	/* check proximity */
231			if (source[sn].sflags & SPROX &&
232			d > source[sn].sl.prox)
233			return(0.0);
234	greg	1.1
235			if (norm != NULL)
236			ddot /= d;
237			else
238			ddot = 1.0;
239	greg	1.6	/* check angle */
240			if (source[sn].sflags & SSPOT) {
241			if (source[sn].sl.s->siz < 2.0PI
242			(1.0 + DOT(source[sn].sl.s->aim,sr->rdir)))
243			return(0.0);
244			d += source[sn].sl.s->flen;
245			}
246	greg	1.1	/* return domega */
247	greg	1.4	return(ddotsource[sn].ss2/(dd));
248	greg	1.1	}
249			}
250
251
252			sourcehit(r) /* check to see if ray hit distant source */
253			register RAY *r;
254			{
255			int first, last;
256			register int i;
257
258			if (r->rsrc >= 0) { /* check only one if aimed */
259			first = last = r->rsrc;
260			} else { /* otherwise check all */
261			first = 0; last = nsources-1;
262			}
263			for (i = first; i <= last; i++)
264	greg	1.4	if (source[i].sflags & SDISTANT)
265	greg	1.1	/*
266			* Check to see if ray is within
267			* solid angle of source.
268			*/
269	greg	1.4	if (2.0PI (1.0 - DOT(source[i].sloc,r->rdir))
270			<= source[i].ss2) {
271			r->ro = source[i].so;
272			if (!(source[i].sflags & SSKIP))
273	greg	1.1	break;
274			}
275
276			if (r->ro != NULL) {
277			for (i = 0; i < 3; i++)
278			r->ron[i] = -r->rdir[i];
279			r->rod = 1.0;
280	greg	1.3	r->rofs = 1.0; setident4(r->rofx);
281			r->robs = 1.0; setident4(r->robx);
282	greg	1.1	return(1);
283			}
284			return(0);
285			}
286
287
288	greg	1.4	static int
289			cntcmp(sc1, sc2) /* contribution compare (descending) */
290	greg	1.9	register CNTPTR sc1, sc2;
291	greg	1.4	{
292			if (sc1->brt > sc2->brt)
293			return(-1);
294			if (sc1->brt < sc2->brt)
295			return(1);
296			return(0);
297			}
298
299
300			direct(r, f, p) /* add direct component */
301			RAY r; / ray that hit surface */
302			int (f)(); / direct component coefficient function */
303			char p; / data for f */
304			{
305	greg	1.12	extern double pow();
306	greg	1.4	register int sn;
307			register CONTRIB *srccnt;
308	greg	1.9	register CNTPTR *cntord;
309	greg	1.12	int nshadcheck, ncnts;
310	greg	1.10	double prob, ourthresh, hwt, test2, hit2;
311	greg	1.4	RAY sr;
312
313	greg	1.9	srccnt = (CONTRIB )malloc(nsourcessizeof(CONTRIB));
314			cntord = (CNTPTR )malloc(nsourcessizeof(CNTPTR));
315			if (srccnt == NULL \|\| cntord == NULL)
316	greg	1.4	error(SYSTEM, "out of memory in direct");
317	greg	1.12	/* compute number to check */
318			nshadcheck = pow((double)nsources, shadcert) + .5;
319	greg	1.8	/* modify threshold */
320			ourthresh = shadthresh / r->rweight;
321	greg	1.4	/* potential contributions */
322			for (sn = 0; sn < nsources; sn++) {
323	greg	1.9	cntord[sn].sno = sn;
324			cntord[sn].brt = 0.0;
325	greg	1.4	/* get source ray */
326			if ((srccnt[sn].dom = srcray(&sr, r, sn)) == 0.0)
327			continue;
328			VCOPY(srccnt[sn].dir, sr.rdir);
329			/* compute coefficient */
330			(*f)(srccnt[sn].val, p, srccnt[sn].dir, srccnt[sn].dom);
331	greg	1.9	cntord[sn].brt = bright(srccnt[sn].val);
332	greg	1.15	if (cntord[sn].brt <= 0.0)
333	greg	1.4	continue;
334			/* compute intersection */
335			if (!( source[sn].sflags & SDISTANT ?
336			sourcehit(&sr) :
337			(*ofun[source[sn].so->otype].funp)
338			(source[sn].so, &sr) ))
339			continue;
340			/* compute contribution */
341			rayshade(&sr, sr.ro->omod);
342			multcolor(srccnt[sn].val, sr.rcol);
343	greg	1.9	cntord[sn].brt = bright(srccnt[sn].val);
344	greg	1.4	}
345			/* sort contributions */
346	greg	1.9	qsort(cntord, nsources, sizeof(CNTPTR), cntcmp);
347	greg	1.13	{ /* find last */
348			register int l, m;
349
350			sn = 0; ncnts = l = nsources;
351			while ((m = (sn + ncnts) >> 1) != l) {
352			if (cntord[m].brt > 0.0)
353			sn = m;
354			else
355			ncnts = m;
356			l = m;
357			}
358			}
359	greg	1.12	/* accumulate tail */
360			for (sn = ncnts-1; sn > 0; sn--)
361			cntord[sn-1].brt += cntord[sn].brt;
362			/* start with prob=.5 */
363			hit2 = 0.5; test2 = 1.0;
364	greg	1.10	/* test for shadows */
365	greg	1.12	for (sn = 0; sn < ncnts; sn++) {
366	greg	1.10	/* check threshold */
367	greg	1.12	if ((sn+nshadcheck>=ncnts ? cntord[sn].brt :
368			cntord[sn].brt-cntord[sn+nshadcheck].brt) <
369			ourthresh*bright(r->rcol))
370	greg	1.4	break;
371			/* get statistics */
372	greg	1.9	hwt = (double)source[cntord[sn].sno].nhits /
373			(double)source[cntord[sn].sno].ntests;
374	greg	1.4	test2 += hwt;
375	greg	1.9	source[cntord[sn].sno].ntests++;
376	greg	1.4	/* test for hit */
377			rayorigin(&sr, r, SHADOW, 1.0);
378	greg	1.9	VCOPY(sr.rdir, srccnt[cntord[sn].sno].dir);
379	greg	1.4	if (localhit(&sr, &thescene) &&
380	greg	1.9	sr.ro != source[cntord[sn].sno].so) {
381	greg	1.4	/* check for transmission */
382	greg	1.14	rayshade(&sr, sr.ro->omod);
383	greg	1.5	if (bright(sr.rcol) <= FTINY)
384	greg	1.4	continue; /* missed! */
385	greg	1.9	(*f)(srccnt[cntord[sn].sno].val, p,
386			srccnt[cntord[sn].sno].dir,
387			srccnt[cntord[sn].sno].dom);
388			multcolor(srccnt[cntord[sn].sno].val, sr.rcol);
389	greg	1.4	}
390			/* add contribution if hit */
391	greg	1.9	addcolor(r->rcol, srccnt[cntord[sn].sno].val);
392	greg	1.4	hit2 += hwt;
393	greg	1.9	source[cntord[sn].sno].nhits++;
394	greg	1.4	}
395	greg	1.7	/* weighted hit rate */
396			hwt = hit2 / test2;
397	greg	1.4	#ifdef DEBUG
398	greg	1.12	sprintf(errmsg, "%d tested, %d untested, %f hit rate\n",
399			sn, ncnts-sn, hwt);
400			eputs(errmsg);
401	greg	1.4	#endif
402			/* add in untested sources */
403	greg	1.12	for ( ; sn < ncnts; sn++) {
404	greg	1.9	prob = hwt * (double)source[cntord[sn].sno].nhits /
405			(double)source[cntord[sn].sno].ntests;
406			scalecolor(srccnt[cntord[sn].sno].val, prob);
407			addcolor(r->rcol, srccnt[cntord[sn].sno].val);
408	greg	1.4	}
409	greg	1.10
410	greg	1.4	free(srccnt);
411	greg	1.9	free(cntord);
412	greg	1.4	}
413
414
415	greg	1.1	#define wrongsource(m, r) (m->otype!=MAT_ILLUM && \
416			r->rsrc>=0 && \
417	greg	1.4	source[r->rsrc].so!=r->ro)
418	greg	1.1
419			#define badambient(m, r) ((r->crtype&(AMBIENT\|SHADOW))==AMBIENT && \
420	greg	1.6	!(r->rtype&REFLECTED) && /* hack! */\
421			!(m->otype==MAT_GLOW&&r->rot>m->oargs.farg[3]))
422	greg	1.1
423			#define passillum(m, r) (m->otype==MAT_ILLUM && \
424	greg	1.4	!(r->rsrc>=0&&source[r->rsrc].so==r->ro))
425	greg	1.1
426
427			m_light(m, r) /* ray hit a light source */
428			register OBJREC *m;
429			register RAY *r;
430			{
431			/* check for behind */
432			if (r->rod < 0.0)
433			return;
434			/* check for over-counting */
435			if (wrongsource(m, r) \|\| badambient(m, r))
436			return;
437			/* check for passed illum */
438			if (passillum(m, r)) {
439
440			if (m->oargs.nsargs < 1 \|\| !strcmp(m->oargs.sarg[0], VOIDID))
441			raytrans(r);
442			else
443			rayshade(r, modifier(m->oargs.sarg[0]));
444
445			/* otherwise treat as source */
446			} else {
447			/* get distribution pattern */
448			raytexture(r, m->omod);
449			/* get source color */
450			setcolor(r->rcol, m->oargs.farg[0],
451			m->oargs.farg[1],
452			m->oargs.farg[2]);
453			/* modify value */
454			multcolor(r->rcol, r->pcol);
455			}
456			}
457
458
459			o_source() {} /* intersection with a source is done elsewhere */