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 (source[ns].sflags & SDISTANT)
                                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 */
}


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|SVIRTUAL)) == 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->rox = NULL;
                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 int  (*trace)();
        register int  sn;
        register CONTRIB  *scp;
        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;
                scp = srccnt + sn;
                scp->sno = sr.rsrc;
                                                /* compute coefficient */
                (*f)(scp->coef, p, sr.rdir, si.dom);
                cntord[sn].brt = bright(scp->coef);
                if (cntord[sn].brt <= 0.0)
                        continue;
                VCOPY(scp->dir, sr.rdir);
                                                /* compute potential */
                sr.revf = srcvalue;
                rayvalue(&sr);
                copycolor(scp->val, sr.rcol);
                multcolor(scp->val, scp->coef);
                cntord[sn].brt = bright(scp->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;
                scp = srccnt + cntord[sn].sndx;
                                                /* test for hit */
                rayorigin(&sr, r, SHADOW, 1.0);
                VCOPY(sr.rdir, scp->dir);
                sr.rsrc = scp->sno;
                source[scp->sno].ntests++;      /* keep statistics */
                if (localhit(&sr, &thescene) &&
                                ( sr.ro != source[scp->sno].so ||
                                source[scp->sno].sflags & SFOLLOW )) {
                                                /* follow entire path */
                        raycont(&sr);
                        if (trace != NULL)
                                (*trace)(&sr);  /* trace execution */
                        if (bright(sr.rcol) <= FTINY)
                                continue;       /* missed! */
                        copycolor(scp->val, sr.rcol);
                        multcolor(scp->val, scp->coef);
                }
                                                /* add contribution if hit */
                addcolor(r->rcol, scp->val);
                nhits++;
                source[scp->sno].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++) {
                scp = srccnt + cntord[sn].sndx;
                prob = hwt * (double)source[scp->sno].nhits /
                                (double)source[scp->sno].ntests;
                scalecolor(scp->val, prob);
                addcolor(r->rcol, scp->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, makespot(m), 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:	2.8
Committed:	Sat Nov 14 13:58:23 1992 UTC (31 years, 5 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.7:	+2 -2 lines
Log Message:	minor generalizations
#	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	2.8	if (source[ns].sflags & SDISTANT)
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	2.5	sourcehit(r) /* check to see if ray hit distant source */
187			register RAY *r;
188			{
189			int first, last;
190			register int i;
191
192			if (r->rsrc >= 0) { /* check only one if aimed */
193			first = last = r->rsrc;
194			} else { /* otherwise check all */
195			first = 0; last = nsources-1;
196			}
197			for (i = first; i <= last; i++)
198			if ((source[i].sflags & (SDISTANT\|SVIRTUAL)) == SDISTANT)
199			/*
200			* Check to see if ray is within
201			* solid angle of source.
202			*/
203			if (2.0PI (1.0 - DOT(source[i].sloc,r->rdir))
204			<= source[i].ss2) {
205			r->ro = source[i].so;
206			if (!(source[i].sflags & SSKIP))
207			break;
208			}
209
210			if (r->ro != NULL) {
211			for (i = 0; i < 3; i++)
212			r->ron[i] = -r->rdir[i];
213			r->rod = 1.0;
214			r->rox = NULL;
215			return(1);
216			}
217			return(0);
218			}
219
220
221	greg	1.4	static int
222			cntcmp(sc1, sc2) /* contribution compare (descending) */
223	greg	1.9	register CNTPTR sc1, sc2;
224	greg	1.4	{
225			if (sc1->brt > sc2->brt)
226			return(-1);
227			if (sc1->brt < sc2->brt)
228			return(1);
229			return(0);
230			}
231
232
233			direct(r, f, p) /* add direct component */
234			RAY r; / ray that hit surface */
235			int (f)(); / direct component coefficient function */
236			char p; / data for f */
237			{
238	greg	1.42	extern int (*trace)();
239	greg	1.4	register int sn;
240	greg	2.7	register CONTRIB *scp;
241	greg	1.45	SRCINDEX si;
242	greg	1.12	int nshadcheck, ncnts;
243	greg	1.29	int nhits;
244	greg	1.45	double prob, ourthresh, hwt;
245	greg	1.4	RAY sr;
246	greg	1.25	/* NOTE: srccnt and cntord global so no recursion */
247	greg	1.22	if (nsources <= 0)
248	greg	1.25	return; /* no sources?! */
249	greg	1.4	/* potential contributions */
250	greg	1.45	initsrcindex(&si);
251			for (sn = 0; srcray(&sr, r, &si); sn++) {
252			if (sn >= maxcntr) {
253			maxcntr = sn + MAXSPART;
254			srccnt = (CONTRIB )realloc((char )srccnt,
255			maxcntr*sizeof(CONTRIB));
256			cntord = (CNTPTR )realloc((char )cntord,
257			maxcntr*sizeof(CNTPTR));
258	greg	1.48	if (srccnt == NULL \| cntord == NULL)
259	greg	1.45	error(SYSTEM, "out of memory in direct");
260			}
261			cntord[sn].sndx = sn;
262	greg	2.7	scp = srccnt + sn;
263			scp->sno = sr.rsrc;
264	greg	1.4	/* compute coefficient */
265	greg	2.7	(*f)(scp->coef, p, sr.rdir, si.dom);
266			cntord[sn].brt = bright(scp->coef);
267	greg	1.15	if (cntord[sn].brt <= 0.0)
268	greg	1.4	continue;
269	greg	2.7	VCOPY(scp->dir, sr.rdir);
270	greg	1.35	/* compute potential */
271			sr.revf = srcvalue;
272			rayvalue(&sr);
273	greg	2.7	copycolor(scp->val, sr.rcol);
274			multcolor(scp->val, scp->coef);
275			cntord[sn].brt = bright(scp->val);
276	greg	1.4	}
277			/* sort contributions */
278	greg	1.45	qsort(cntord, sn, sizeof(CNTPTR), cntcmp);
279	greg	1.13	{ /* find last */
280			register int l, m;
281
282	greg	1.45	ncnts = l = sn;
283			sn = 0;
284	greg	1.13	while ((m = (sn + ncnts) >> 1) != l) {
285			if (cntord[m].brt > 0.0)
286			sn = m;
287			else
288			ncnts = m;
289			l = m;
290			}
291			}
292	greg	2.2	if (ncnts == 0)
293			return; /* no contributions! */
294	greg	1.12	/* accumulate tail */
295			for (sn = ncnts-1; sn > 0; sn--)
296			cntord[sn-1].brt += cntord[sn].brt;
297	greg	1.45	/* compute number to check */
298			nshadcheck = pow((double)ncnts, shadcert) + .5;
299			/* modify threshold */
300			ourthresh = shadthresh / r->rweight;
301	greg	1.10	/* test for shadows */
302	greg	1.29	nhits = 0;
303	greg	1.12	for (sn = 0; sn < ncnts; sn++) {
304	greg	1.10	/* check threshold */
305	greg	1.12	if ((sn+nshadcheck>=ncnts ? cntord[sn].brt :
306	greg	1.27	cntord[sn].brt-cntord[sn+nshadcheck].brt)
307			< ourthresh*bright(r->rcol))
308	greg	1.4	break;
309	greg	2.7	scp = srccnt + cntord[sn].sndx;
310	greg	1.4	/* test for hit */
311			rayorigin(&sr, r, SHADOW, 1.0);
312	greg	2.7	VCOPY(sr.rdir, scp->dir);
313			sr.rsrc = scp->sno;
314			source[scp->sno].ntests++; /* keep statistics */
315	greg	1.4	if (localhit(&sr, &thescene) &&
316	greg	2.7	( sr.ro != source[scp->sno].so \|\|
317			source[scp->sno].sflags & SFOLLOW )) {
318	greg	1.33	/* follow entire path */
319	greg	1.19	raycont(&sr);
320	greg	1.42	if (trace != NULL)
321			(trace)(&sr); / trace execution */
322	greg	1.5	if (bright(sr.rcol) <= FTINY)
323	greg	1.4	continue; /* missed! */
324	greg	2.7	copycolor(scp->val, sr.rcol);
325			multcolor(scp->val, scp->coef);
326	greg	1.4	}
327			/* add contribution if hit */
328	greg	2.7	addcolor(r->rcol, scp->val);
329	greg	1.29	nhits++;
330	greg	2.7	source[scp->sno].nhits++;
331	greg	1.4	}
332	greg	1.29	/* surface hit rate */
333			if (sn > 0)
334			hwt = (double)nhits / (double)sn;
335			else
336			hwt = 0.5;
337	greg	1.20	#ifdef DEBUG
338	greg	1.12	sprintf(errmsg, "%d tested, %d untested, %f hit rate\n",
339			sn, ncnts-sn, hwt);
340			eputs(errmsg);
341	greg	1.4	#endif
342			/* add in untested sources */
343	greg	1.12	for ( ; sn < ncnts; sn++) {
344	greg	2.7	scp = srccnt + cntord[sn].sndx;
345			prob = hwt * (double)source[scp->sno].nhits /
346			(double)source[scp->sno].ntests;
347			scalecolor(scp->val, prob);
348			addcolor(r->rcol, scp->val);
349	greg	1.1	}
350	greg	2.4	}
351
352
353			/****************************************************************
354			* The following macros were separated from the m_light() routine
355			* because they are very nasty and difficult to understand.
356			*/
357
358			/* wrongillum *
359			*
360			* We cannot allow an illum to pass to another illum, because that
361			* would almost certainly constitute overcounting.
362			* However, we do allow an illum to pass to another illum
363			* that is actually going to relay to a virtual light source.
364			*/
365
366			#define wrongillum(m, r) (!(source[r->rsrc].sflags&SVIRTUAL) && \
367			objptr(source[r->rsrc].so->omod)->otype==MAT_ILLUM)
368
369			/* wrongsource *
370			*
371			* This source is the wrong source (ie. overcounted) if we are
372			* aimed to a different source than the one we hit and the one
373			* we hit is not an illum which should be passed.
374			*/
375
376			#define wrongsource(m, r) (r->rsrc>=0 && source[r->rsrc].so!=r->ro && \
377			(m->otype!=MAT_ILLUM \|\| wrongillum(m,r)))
378
379			/* distglow *
380			*
381			* A distant glow is an object that sometimes acts as a light source,
382			* but is too far away from the test point to be one in this case.
383			*/
384
385			#define distglow(m, r) (m->otype==MAT_GLOW && \
386			r->rot > m->oargs.farg[3])
387
388			/* badcomponent *
389			*
390			* We must avoid counting light sources in the ambient calculation,
391			* since the direct component is handled separately. Therefore, any
392			* ambient ray which hits an active light source must be discarded.
393			* The same is true for stray specular samples, since the specular
394			* contribution from light sources is calculated separately.
395			*/
396
397			#define badcomponent(m, r) (r->crtype&(AMBIENT\|SPECULAR) && \
398			!(r->crtype&SHADOW \|\| r->rod < 0.0 \|\| \
399			distglow(m, r)))
400
401			/* overcount *
402			*
403			* All overcounting possibilities are contained here.
404			*/
405
406			#define overcount(m, r) (badcomponent(m,r) \|\| wrongsource(m,r))
407
408			/* passillum *
409			*
410			* An illum passes to another material type when we didn't hit it
411			* on purpose (as part of a direct calculation), or it is relaying
412			* a virtual light source.
413			*/
414
415			#define passillum(m, r) (m->otype==MAT_ILLUM && \
416			(r->rsrc<0 \|\| source[r->rsrc].so!=r->ro \|\| \
417			source[r->rsrc].sflags&SVIRTUAL))
418
419			/* srcignore *
420			*
421			* The -di flag renders light sources invisible, and here is the test.
422			*/
423
424			#define srcignore(m, r) (directinvis && !(r->crtype&SHADOW) && \
425			!distglow(m, r))
426
427
428			m_light(m, r) /* ray hit a light source */
429			register OBJREC *m;
430			register RAY *r;
431			{
432			/* check for over-counting */
433			if (overcount(m, r))
434			return;
435			/* check for passed illum */
436			if (passillum(m, r)) {
437			if (m->oargs.nsargs < 1 \|\| !strcmp(m->oargs.sarg[0], VOIDID))
438			raytrans(r);
439			else
440			rayshade(r, modifier(m->oargs.sarg[0]));
441			return;
442			}
443			/* otherwise treat as source */
444			/* check for behind */
445			if (r->rod < 0.0)
446			return;
447			/* check for invisibility */
448			if (srcignore(m, r))
449			return;
450			/* check for outside spot */
451	greg	2.8	if (m->otype==MAT_SPOT && spotout(r, makespot(m), r->rot>=FHUGE))
452	greg	2.4	return;
453			/* get distribution pattern */
454			raytexture(r, m->omod);
455			/* get source color */
456			setcolor(r->rcol, m->oargs.farg[0],
457			m->oargs.farg[1],
458			m->oargs.farg[2]);
459			/* modify value */
460			multcolor(r->rcol, r->pcol);
461	greg	1.1	}