src/rt/source.c

/* Copyright (c) 1992 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  "otypes.h"

#include  "source.h"

/*
 * Structures used by direct()
 */

typedef struct {
        int  sno;               /* source number */
        FVECT  dir;             /* source direction */
        COLOR  coef;            /* material coefficient */
        COLOR  val;             /* contribution */
}  CONTRIB;             /* direct contribution */

typedef struct {
        int  sndx;              /* source index (to CONTRIB array) */
        float  brt;             /* brightness (for comparison) */
}  CNTPTR;              /* contribution pointer */

static CONTRIB  *srccnt;                /* source contributions in direct() */
static CNTPTR  *cntord;                 /* source ordering in direct() */
static int  maxcntr = 0;                /* size of contribution arrays */


marksources()                   /* find and mark source objects */
{
        int  foundsource = 0;
        int  i;
        register OBJREC  *o, *m;
        register int  ns;
                                        /* initialize dispatch table */
        initstypes();
                                        /* find direct sources */
        for (i = 0; i < nobjects; i++) {
        
                o = objptr(i);

                if (!issurface(o->otype) || o->omod == OVOID)
                        continue;

                m = objptr(o->omod);

                if (!islight(m->otype))
                        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 (sfun[o->otype].of == NULL ||
                                sfun[o->otype].of->setsrc == NULL)
                        objerror(o, USER, "illegal material");

                if ((ns = newsource()) < 0)
                        goto memerr;

                setsource(&source[ns], o);

                if (m->otype == MAT_GLOW) {
                        source[ns].sflags |= SPROX;
                        source[ns].sl.prox = m->oargs.farg[3];
                        if (o->otype == OBJ_SOURCE)
                                source[ns].sflags |= SSKIP;
                } else if (m->otype == MAT_SPOT) {
                        source[ns].sflags |= SSPOT;
                        if ((source[ns].sl.s = makespot(m)) == NULL)
                                goto memerr;
                        if (source[ns].sflags & SFLAT &&
                                !checkspot(source[ns].sl.s,source[ns].snorm)) {
                                objerror(o, WARNING,
                                        "invalid spotlight direction");
                                source[ns].sflags |= SSKIP;
                        }
                }
                if (!(source[ns].sflags & SSKIP))
                        foundsource++;
        }
        if (!foundsource) {
                error(WARNING, "no light sources found");
                return;
        }
        markvirtuals();                 /* find and add virtual sources */
                                /* allocate our contribution arrays */
        maxcntr = nsources + MAXSPART;  /* start with this many */
        srccnt = (CONTRIB *)malloc(maxcntr*sizeof(CONTRIB));
        cntord = (CNTPTR *)malloc(maxcntr*sizeof(CNTPTR));
        if (srccnt == NULL | cntord == NULL)
                goto memerr;
        return;
memerr:
        error(SYSTEM, "out of memory in marksources");
}


srcray(sr, r, si)               /* send a ray to a source, return domega */
register RAY  *sr;              /* returned source ray */
RAY  *r;                        /* ray which hit object */
SRCINDEX  *si;                  /* source sample index */
{
    double  d;                          /* distance to source */
    register SRCREC  *srcp;

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

    while ((d = nextssamp(sr, si)) != 0.0) {
        sr->rsrc = si->sn;                      /* remember source */
        srcp = source + si->sn;
        if (srcp->sflags & SDISTANT) {
                if (srcp->sflags & SSPOT && spotout(sr, srcp->sl.s, 1))
                        continue;
                return(1);              /* sample OK */
        }
                                /* local source */
                                                /* check proximity */
        if (srcp->sflags & SPROX && d > srcp->sl.prox)
                continue;
                                                /* check angle */
        if (srcp->sflags & SSPOT) {
                if (spotout(sr, srcp->sl.s, 0))
                        continue;
                                        /* adjust solid angle */
                si->dom *= d*d;
                d += srcp->sl.s->flen;
                si->dom /= d*d;
        }
        return(1);                      /* sample OK */
    }
    return(0);                  /* no more samples */
}


srcvalue(r)                     /* punch ray to source and compute value */
RAY  *r;
{
        register SRCREC  *sp;

        sp = &source[r->rsrc];
        if (sp->sflags & SVIRTUAL) {    /* virtual source */
                                        /* check intersection */
                if (!(*ofun[sp->so->otype].funp)(sp->so, r))
                        return;
                raycont(r);             /* compute contribution */
                return;
        }
                                        /* compute intersection */
        if (sp->sflags & SDISTANT ? sourcehit(r) :
                        (*ofun[sp->so->otype].funp)(sp->so, r)) {
                if (sp->sa.success >= 0)
                        sp->sa.success++;
                raycont(r);             /* compute contribution */
                return;
        }
        if (sp->sa.success < 0)
                return;                 /* bitched already */
        sp->sa.success -= AIMREQT;
        if (sp->sa.success >= 0)
                return;                 /* leniency */
        sprintf(errmsg, "aiming failure for light source \"%s\"",
                        sp->so->oname);
        error(WARNING, errmsg);         /* issue warning */
}


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 int  (*trace)();
        extern double  pow();
        register int  sn;
        SRCINDEX  si;
        int  nshadcheck, ncnts;
        int  nhits;
        double  prob, ourthresh, hwt;
        RAY  sr;
                        /* NOTE: srccnt and cntord global so no recursion */
        if (nsources <= 0)
                return;         /* no sources?! */
                                                /* potential contributions */
        initsrcindex(&si);
        for (sn = 0; srcray(&sr, r, &si); sn++) {
                if (sn >= maxcntr) {
                        maxcntr = sn + MAXSPART;
                        srccnt = (CONTRIB *)realloc((char *)srccnt,
                                        maxcntr*sizeof(CONTRIB));
                        cntord = (CNTPTR *)realloc((char *)cntord,
                                        maxcntr*sizeof(CNTPTR));
                        if (srccnt == NULL | cntord == NULL)
                                error(SYSTEM, "out of memory in direct");
                }
                cntord[sn].sndx = sn;
                srccnt[sn].sno = sr.rsrc;
                                                /* compute coefficient */
                (*f)(srccnt[sn].coef, p, sr.rdir, si.dom);
                cntord[sn].brt = bright(srccnt[sn].coef);
                if (cntord[sn].brt <= 0.0)
                        continue;
                VCOPY(srccnt[sn].dir, sr.rdir);
                                                /* compute potential */
                sr.revf = srcvalue;
                rayvalue(&sr);
                copycolor(srccnt[sn].val, sr.rcol);
                multcolor(srccnt[sn].val, srccnt[sn].coef);
                cntord[sn].brt = bright(srccnt[sn].val);
        }
                                                /* sort contributions */
        qsort(cntord, sn, sizeof(CNTPTR), cntcmp);
        {                                       /* find last */
                register int  l, m;

                ncnts = l = sn;
                sn = 0;
                while ((m = (sn + ncnts) >> 1) != l) {
                        if (cntord[m].brt > 0.0)
                                sn = m;
                        else
                                ncnts = m;
                        l = m;
                }
        }
        if (ncnts == 0)
                return;         /* no contributions! */
                                                /* accumulate tail */
        for (sn = ncnts-1; sn > 0; sn--)
                cntord[sn-1].brt += cntord[sn].brt;
                                                /* compute number to check */
        nshadcheck = pow((double)ncnts, shadcert) + .5;
                                                /* modify threshold */
        ourthresh = shadthresh / r->rweight;
                                                /* test for shadows */
        nhits = 0;
        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;
                                                /* test for hit */
                rayorigin(&sr, r, SHADOW, 1.0);
                VCOPY(sr.rdir, srccnt[cntord[sn].sndx].dir);
                sr.rsrc = srccnt[cntord[sn].sndx].sno;
                source[sr.rsrc].ntests++;       /* keep statistics */
                if (localhit(&sr, &thescene) &&
                                ( sr.ro != source[sr.rsrc].so ||
                                source[sr.rsrc].sflags & SFOLLOW )) {
                                                /* follow entire path */
                        raycont(&sr);
                        if (trace != NULL)
                                (*trace)(&sr);  /* trace execution */
                        if (bright(sr.rcol) <= FTINY)
                                continue;       /* missed! */
                        copycolor(srccnt[cntord[sn].sndx].val, sr.rcol);
                        multcolor(srccnt[cntord[sn].sndx].val,
                                        srccnt[cntord[sn].sndx].coef);
                }
                                                /* add contribution if hit */
                addcolor(r->rcol, srccnt[cntord[sn].sndx].val);
                nhits++;
                source[sr.rsrc].nhits++;
        }
                                        /* surface hit rate */
        if (sn > 0)
                hwt = (double)nhits / (double)sn;
        else
                hwt = 0.5;
#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++) {
                sr.rsrc = srccnt[cntord[sn].sndx].sno;
                prob = hwt * (double)source[sr.rsrc].nhits /
                                (double)source[sr.rsrc].ntests;
                scalecolor(srccnt[cntord[sn].sndx].val, prob);
                addcolor(r->rcol, srccnt[cntord[sn].sndx].val);
        }
}


/****************************************************************
 * The following macros were separated from the m_light() routine
 * because they are very nasty and difficult to understand.
 */

/* wrongillum *
 *
 * We cannot allow an illum to pass to another illum, because that
 * would almost certainly constitute overcounting.
 * However, we do allow an illum to pass to another illum
 * that is actually going to relay to a virtual light source.
 */

#define  wrongillum(m, r)       (!(source[r->rsrc].sflags&SVIRTUAL) && \
                        objptr(source[r->rsrc].so->omod)->otype==MAT_ILLUM)

/* wrongsource *
 *
 * This source is the wrong source (ie. overcounted) if we are
 * aimed to a different source than the one we hit and the one
 * we hit is not an illum which should be passed.
 */

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

/* distglow *
 *
 * A distant glow is an object that sometimes acts as a light source,
 * but is too far away from the test point to be one in this case.
 */

#define  distglow(m, r)         (m->otype==MAT_GLOW && \
                                r->rot > m->oargs.farg[3])

/* badcomponent *
 *
 * We must avoid counting light sources in the ambient calculation,
 * since the direct component is handled separately.  Therefore, any
 * ambient ray which hits an active light source must be discarded.
 * The same is true for stray specular samples, since the specular
 * contribution from light sources is calculated separately.
 */

#define  badcomponent(m, r)     (r->crtype&(AMBIENT|SPECULAR) && \
                                !(r->crtype&SHADOW || r->rod < 0.0 || \
                                        distglow(m, r)))

/* overcount *
 *
 * All overcounting possibilities are contained here.
 */

#define  overcount(m, r)        (badcomponent(m,r) || wrongsource(m,r))

/* passillum *
 *
 * An illum passes to another material type when we didn't hit it
 * on purpose (as part of a direct calculation), or it is relaying
 * a virtual light source.
 */

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

/* srcignore *
 *
 * The -di flag renders light sources invisible, and here is the test.
 */

#define  srcignore(m, r)        (directinvis && !(r->crtype&SHADOW) && \
                                !distglow(m, r))


m_light(m, r)                   /* ray hit a light source */
register OBJREC  *m;
register RAY  *r;
{
                                                /* check for over-counting */
        if (overcount(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]));
                return;
        }
                                        /* otherwise treat as source */
                                                /* check for behind */
        if (r->rod < 0.0)
                return;
                                                /* check for invisibility */
        if (srcignore(m, r))
                return;
                                                /* check for outside spot */
        if (m->otype==MAT_SPOT && spotout(r, (SPOT *)m->os, r->rot>=FHUGE))
                return;
                                                /* 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);
}
Revision:	2.4
Committed:	Fri Aug 28 14:07:41 1992 UTC (31 years, 8 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.3:	+115 -15 lines
Log Message:	fixed bug with virtual spotlight sources moved m_light() back to source.c
#	User	Rev	Content
1	greg	2.4	/* 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			* 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 "otypes.h"
18
19	greg	1.35	#include "source.h"
20	greg	1.1
21	greg	1.35	/*
22			* Structures used by direct()
23			*/
24	greg	1.1
25	greg	1.35	typedef struct {
26	greg	1.45	int sno; /* source number */
27	greg	1.35	FVECT dir; /* source direction */
28			COLOR coef; /* material coefficient */
29			COLOR val; /* contribution */
30			} CONTRIB; /* direct contribution */
31	greg	1.1
32	greg	1.35	typedef struct {
33	greg	1.45	int sndx; /* source index (to CONTRIB array) */
34	greg	1.35	float brt; /* brightness (for comparison) */
35			} CNTPTR; /* contribution pointer */
36	greg	1.1
37	greg	1.25	static CONTRIB srccnt; / source contributions in direct() */
38			static CNTPTR cntord; / source ordering in direct() */
39	greg	1.45	static int maxcntr = 0; /* size of contribution arrays */
40	greg	1.1
41	greg	1.25
42	greg	1.1	marksources() /* find and mark source objects */
43			{
44	greg	2.3	int foundsource = 0;
45	greg	1.33	int i;
46	greg	1.1	register OBJREC o, m;
47	greg	1.36	register int ns;
48	greg	1.35	/* initialize dispatch table */
49			initstypes();
50			/* find direct sources */
51	greg	1.1	for (i = 0; i < nobjects; i++) {
52
53			o = objptr(i);
54
55	greg	1.35	if (!issurface(o->otype) \|\| o->omod == OVOID)
56	greg	1.1	continue;
57
58			m = objptr(o->omod);
59
60	greg	1.24	if (!islight(m->otype))
61	greg	1.1	continue;
62
63	greg	1.6	if (m->oargs.nfargs != (m->otype == MAT_GLOW ? 4 :
64			m->otype == MAT_SPOT ? 7 : 3))
65	greg	1.1	objerror(m, USER, "bad # arguments");
66
67	greg	1.6	if (m->otype == MAT_GLOW &&
68			o->otype != OBJ_SOURCE &&
69			m->oargs.farg[3] <= FTINY)
70	greg	1.1	continue; /* don't bother */
71
72	greg	1.35	if (sfun[o->otype].of == NULL \|\|
73			sfun[o->otype].of->setsrc == NULL)
74			objerror(o, USER, "illegal material");
75
76	greg	1.36	if ((ns = newsource()) < 0)
77	greg	1.25	goto memerr;
78	greg	1.1
79	greg	1.37	setsource(&source[ns], o);
80	greg	1.1
81	greg	1.6	if (m->otype == MAT_GLOW) {
82	greg	1.36	source[ns].sflags \|= SPROX;
83			source[ns].sl.prox = m->oargs.farg[3];
84	greg	1.6	if (o->otype == OBJ_SOURCE)
85	greg	1.36	source[ns].sflags \|= SSKIP;
86	greg	1.6	} else if (m->otype == MAT_SPOT) {
87	greg	1.36	source[ns].sflags \|= SSPOT;
88			if ((source[ns].sl.s = makespot(m)) == NULL)
89	greg	1.33	goto memerr;
90	greg	1.38	if (source[ns].sflags & SFLAT &&
91			!checkspot(source[ns].sl.s,source[ns].snorm)) {
92			objerror(o, WARNING,
93			"invalid spotlight direction");
94			source[ns].sflags \|= SSKIP;
95			}
96	greg	1.6	}
97	greg	2.3	if (!(source[ns].sflags & SSKIP))
98			foundsource++;
99	greg	1.1	}
100	greg	2.3	if (!foundsource) {
101	greg	1.25	error(WARNING, "no light sources found");
102			return;
103			}
104	greg	1.33	markvirtuals(); /* find and add virtual sources */
105	greg	1.45	/* allocate our contribution arrays */
106	greg	1.48	maxcntr = nsources + MAXSPART; /* start with this many */
107	greg	1.45	srccnt = (CONTRIB )malloc(maxcntrsizeof(CONTRIB));
108			cntord = (CNTPTR )malloc(maxcntrsizeof(CNTPTR));
109	greg	1.48	if (srccnt == NULL \| cntord == NULL)
110	greg	1.33	goto memerr;
111			return;
112	greg	1.25	memerr:
113			error(SYSTEM, "out of memory in marksources");
114	greg	1.1	}
115
116
117	greg	1.45	srcray(sr, r, si) /* send a ray to a source, return domega */
118	greg	1.1	register RAY sr; / returned source ray */
119			RAY r; / ray which hit object */
120	greg	1.45	SRCINDEX si; / source sample index */
121	greg	1.1	{
122	greg	1.45	double d; /* distance to source */
123			register SRCREC *srcp;
124	greg	1.1
125	greg	1.45	rayorigin(sr, r, SHADOW, 1.0); /* ignore limits */
126	greg	1.1
127	greg	1.47	while ((d = nextssamp(sr, si)) != 0.0) {
128	greg	1.45	sr->rsrc = si->sn; /* remember source */
129			srcp = source + si->sn;
130			if (srcp->sflags & SDISTANT) {
131	greg	2.4	if (srcp->sflags & SSPOT && spotout(sr, srcp->sl.s, 1))
132			continue;
133	greg	1.45	return(1); /* sample OK */
134	greg	1.40	}
135	greg	1.45	/* local source */
136	greg	1.6	/* check proximity */
137	greg	1.45	if (srcp->sflags & SPROX && d > srcp->sl.prox)
138			continue;
139	greg	1.6	/* check angle */
140	greg	1.45	if (srcp->sflags & SSPOT) {
141	greg	2.4	if (spotout(sr, srcp->sl.s, 0))
142	greg	1.45	continue;
143			/* adjust solid angle */
144			si->dom = dd;
145			d += srcp->sl.s->flen;
146			si->dom /= d*d;
147	greg	1.1	}
148	greg	1.45	return(1); /* sample OK */
149			}
150			return(0); /* no more samples */
151	greg	1.1	}
152
153
154	greg	1.35	srcvalue(r) /* punch ray to source and compute value */
155			RAY *r;
156	greg	1.1	{
157	greg	1.35	register SRCREC *sp;
158	greg	1.1
159	greg	1.35	sp = &source[r->rsrc];
160			if (sp->sflags & SVIRTUAL) { /* virtual source */
161			/* check intersection */
162			if (!(*ofun[sp->so->otype].funp)(sp->so, r))
163			return;
164			raycont(r); /* compute contribution */
165			return;
166	greg	1.1	}
167	greg	1.35	/* compute intersection */
168			if (sp->sflags & SDISTANT ? sourcehit(r) :
169			(*ofun[sp->so->otype].funp)(sp->so, r)) {
170			if (sp->sa.success >= 0)
171			sp->sa.success++;
172			raycont(r); /* compute contribution */
173			return;
174	greg	1.1	}
175	greg	1.35	if (sp->sa.success < 0)
176			return; /* bitched already */
177			sp->sa.success -= AIMREQT;
178			if (sp->sa.success >= 0)
179			return; /* leniency */
180			sprintf(errmsg, "aiming failure for light source \"%s\"",
181			sp->so->oname);
182			error(WARNING, errmsg); /* issue warning */
183	greg	1.1	}
184
185
186	greg	1.4	static int
187			cntcmp(sc1, sc2) /* contribution compare (descending) */
188	greg	1.9	register CNTPTR sc1, sc2;
189	greg	1.4	{
190			if (sc1->brt > sc2->brt)
191			return(-1);
192			if (sc1->brt < sc2->brt)
193			return(1);
194			return(0);
195			}
196
197
198			direct(r, f, p) /* add direct component */
199			RAY r; / ray that hit surface */
200			int (f)(); / direct component coefficient function */
201			char p; / data for f */
202			{
203	greg	1.42	extern int (*trace)();
204	greg	1.12	extern double pow();
205	greg	1.4	register int sn;
206	greg	1.45	SRCINDEX si;
207	greg	1.12	int nshadcheck, ncnts;
208	greg	1.29	int nhits;
209	greg	1.45	double prob, ourthresh, hwt;
210	greg	1.4	RAY sr;
211	greg	1.25	/* NOTE: srccnt and cntord global so no recursion */
212	greg	1.22	if (nsources <= 0)
213	greg	1.25	return; /* no sources?! */
214	greg	1.4	/* potential contributions */
215	greg	1.45	initsrcindex(&si);
216			for (sn = 0; srcray(&sr, r, &si); sn++) {
217			if (sn >= maxcntr) {
218			maxcntr = sn + MAXSPART;
219			srccnt = (CONTRIB )realloc((char )srccnt,
220			maxcntr*sizeof(CONTRIB));
221			cntord = (CNTPTR )realloc((char )cntord,
222			maxcntr*sizeof(CNTPTR));
223	greg	1.48	if (srccnt == NULL \| cntord == NULL)
224	greg	1.45	error(SYSTEM, "out of memory in direct");
225			}
226			cntord[sn].sndx = sn;
227	greg	1.46	srccnt[sn].sno = sr.rsrc;
228	greg	1.4	/* compute coefficient */
229	greg	1.46	(*f)(srccnt[sn].coef, p, sr.rdir, si.dom);
230	greg	1.34	cntord[sn].brt = bright(srccnt[sn].coef);
231	greg	1.15	if (cntord[sn].brt <= 0.0)
232	greg	1.4	continue;
233	greg	1.45	VCOPY(srccnt[sn].dir, sr.rdir);
234	greg	1.35	/* compute potential */
235			sr.revf = srcvalue;
236			rayvalue(&sr);
237	greg	1.34	copycolor(srccnt[sn].val, sr.rcol);
238			multcolor(srccnt[sn].val, srccnt[sn].coef);
239	greg	1.9	cntord[sn].brt = bright(srccnt[sn].val);
240	greg	1.4	}
241			/* sort contributions */
242	greg	1.45	qsort(cntord, sn, sizeof(CNTPTR), cntcmp);
243	greg	1.13	{ /* find last */
244			register int l, m;
245
246	greg	1.45	ncnts = l = sn;
247			sn = 0;
248	greg	1.13	while ((m = (sn + ncnts) >> 1) != l) {
249			if (cntord[m].brt > 0.0)
250			sn = m;
251			else
252			ncnts = m;
253			l = m;
254			}
255			}
256	greg	2.2	if (ncnts == 0)
257			return; /* no contributions! */
258	greg	1.12	/* accumulate tail */
259			for (sn = ncnts-1; sn > 0; sn--)
260			cntord[sn-1].brt += cntord[sn].brt;
261	greg	1.45	/* compute number to check */
262			nshadcheck = pow((double)ncnts, shadcert) + .5;
263			/* modify threshold */
264			ourthresh = shadthresh / r->rweight;
265	greg	1.10	/* test for shadows */
266	greg	1.29	nhits = 0;
267	greg	1.12	for (sn = 0; sn < ncnts; sn++) {
268	greg	1.10	/* check threshold */
269	greg	1.12	if ((sn+nshadcheck>=ncnts ? cntord[sn].brt :
270	greg	1.27	cntord[sn].brt-cntord[sn+nshadcheck].brt)
271			< ourthresh*bright(r->rcol))
272	greg	1.4	break;
273			/* test for hit */
274			rayorigin(&sr, r, SHADOW, 1.0);
275	greg	1.45	VCOPY(sr.rdir, srccnt[cntord[sn].sndx].dir);
276			sr.rsrc = srccnt[cntord[sn].sndx].sno;
277			source[sr.rsrc].ntests++; /* keep statistics */
278	greg	1.4	if (localhit(&sr, &thescene) &&
279	greg	1.45	( sr.ro != source[sr.rsrc].so \|\|
280			source[sr.rsrc].sflags & SFOLLOW )) {
281	greg	1.33	/* follow entire path */
282	greg	1.19	raycont(&sr);
283	greg	1.42	if (trace != NULL)
284			(trace)(&sr); / trace execution */
285	greg	1.5	if (bright(sr.rcol) <= FTINY)
286	greg	1.4	continue; /* missed! */
287	greg	1.45	copycolor(srccnt[cntord[sn].sndx].val, sr.rcol);
288			multcolor(srccnt[cntord[sn].sndx].val,
289			srccnt[cntord[sn].sndx].coef);
290	greg	1.4	}
291			/* add contribution if hit */
292	greg	1.45	addcolor(r->rcol, srccnt[cntord[sn].sndx].val);
293	greg	1.29	nhits++;
294	greg	1.45	source[sr.rsrc].nhits++;
295	greg	1.4	}
296	greg	1.29	/* surface hit rate */
297			if (sn > 0)
298			hwt = (double)nhits / (double)sn;
299			else
300			hwt = 0.5;
301	greg	1.20	#ifdef DEBUG
302	greg	1.12	sprintf(errmsg, "%d tested, %d untested, %f hit rate\n",
303			sn, ncnts-sn, hwt);
304			eputs(errmsg);
305	greg	1.4	#endif
306			/* add in untested sources */
307	greg	1.12	for ( ; sn < ncnts; sn++) {
308	greg	1.45	sr.rsrc = srccnt[cntord[sn].sndx].sno;
309			prob = hwt * (double)source[sr.rsrc].nhits /
310			(double)source[sr.rsrc].ntests;
311			scalecolor(srccnt[cntord[sn].sndx].val, prob);
312			addcolor(r->rcol, srccnt[cntord[sn].sndx].val);
313	greg	1.1	}
314	greg	2.4	}
315
316
317			/****************************************************************
318			* The following macros were separated from the m_light() routine
319			* because they are very nasty and difficult to understand.
320			*/
321
322			/* wrongillum *
323			*
324			* We cannot allow an illum to pass to another illum, because that
325			* would almost certainly constitute overcounting.
326			* However, we do allow an illum to pass to another illum
327			* that is actually going to relay to a virtual light source.
328			*/
329
330			#define wrongillum(m, r) (!(source[r->rsrc].sflags&SVIRTUAL) && \
331			objptr(source[r->rsrc].so->omod)->otype==MAT_ILLUM)
332
333			/* wrongsource *
334			*
335			* This source is the wrong source (ie. overcounted) if we are
336			* aimed to a different source than the one we hit and the one
337			* we hit is not an illum which should be passed.
338			*/
339
340			#define wrongsource(m, r) (r->rsrc>=0 && source[r->rsrc].so!=r->ro && \
341			(m->otype!=MAT_ILLUM \|\| wrongillum(m,r)))
342
343			/* distglow *
344			*
345			* A distant glow is an object that sometimes acts as a light source,
346			* but is too far away from the test point to be one in this case.
347			*/
348
349			#define distglow(m, r) (m->otype==MAT_GLOW && \
350			r->rot > m->oargs.farg[3])
351
352			/* badcomponent *
353			*
354			* We must avoid counting light sources in the ambient calculation,
355			* since the direct component is handled separately. Therefore, any
356			* ambient ray which hits an active light source must be discarded.
357			* The same is true for stray specular samples, since the specular
358			* contribution from light sources is calculated separately.
359			*/
360
361			#define badcomponent(m, r) (r->crtype&(AMBIENT\|SPECULAR) && \
362			!(r->crtype&SHADOW \|\| r->rod < 0.0 \|\| \
363			distglow(m, r)))
364
365			/* overcount *
366			*
367			* All overcounting possibilities are contained here.
368			*/
369
370			#define overcount(m, r) (badcomponent(m,r) \|\| wrongsource(m,r))
371
372			/* passillum *
373			*
374			* An illum passes to another material type when we didn't hit it
375			* on purpose (as part of a direct calculation), or it is relaying
376			* a virtual light source.
377			*/
378
379			#define passillum(m, r) (m->otype==MAT_ILLUM && \
380			(r->rsrc<0 \|\| source[r->rsrc].so!=r->ro \|\| \
381			source[r->rsrc].sflags&SVIRTUAL))
382
383			/* srcignore *
384			*
385			* The -di flag renders light sources invisible, and here is the test.
386			*/
387
388			#define srcignore(m, r) (directinvis && !(r->crtype&SHADOW) && \
389			!distglow(m, r))
390
391
392			m_light(m, r) /* ray hit a light source */
393			register OBJREC *m;
394			register RAY *r;
395			{
396			/* check for over-counting */
397			if (overcount(m, r))
398			return;
399			/* check for passed illum */
400			if (passillum(m, r)) {
401			if (m->oargs.nsargs < 1 \|\| !strcmp(m->oargs.sarg[0], VOIDID))
402			raytrans(r);
403			else
404			rayshade(r, modifier(m->oargs.sarg[0]));
405			return;
406			}
407			/* otherwise treat as source */
408			/* check for behind */
409			if (r->rod < 0.0)
410			return;
411			/* check for invisibility */
412			if (srcignore(m, r))
413			return;
414			/* check for outside spot */
415			if (m->otype==MAT_SPOT && spotout(r, (SPOT *)m->os, r->rot>=FHUGE))
416			return;
417			/* get distribution pattern */
418			raytexture(r, m->omod);
419			/* get source color */
420			setcolor(r->rcol, m->oargs.farg[0],
421			m->oargs.farg[1],
422			m->oargs.farg[2]);
423			/* modify value */
424			multcolor(r->rcol, r->pcol);
425	greg	1.1	}