src/rt/source.c

/* Copyright (c) 1995 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"

#include  "random.h"

extern double  ssampdist;               /* scatter sampling distance */

/*
 * 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 (m->oargs.farg[0] <= FTINY && m->oargs.farg[1] <= FTINY &&
                                m->oargs.farg[2] <= 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))
                        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))
                        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 */
register 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;
                if (!rayshade(r, r->ro->omod))  /* compute contribution */
                        goto nomat;
                rayparticipate(r);
                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++;
                if (!rayshade(r, r->ro->omod))  /* compute contribution */
                        goto nomat;
                rayparticipate(r);
                return;
        }
                                        /* we missed our mark! */
        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 */
        return;
nomat:
        objerror(r->ro, USER, "material not found");
}


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 */
        for (nhits = 0, hwt = 0.0, sn = 0; sn < ncnts;
                        hwt += (double)source[scp->sno].nhits /
                                (double)source[scp->sno].ntests,
                        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 */
                        if (!raycont(&sr))
                                objerror(sr.ro, USER, "material not found");
                        rayparticipate(&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++;
        }
                                        /* source hit rate */
        if (hwt > FTINY)
                hwt = (double)nhits / hwt;
        else
                hwt = 0.5;
#ifdef DEBUG
        sprintf(errmsg, "%d tested, %d untested, %f conditional 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;
                if (prob > 1.0)
                        prob = 1.0;
                scalecolor(scp->val, prob);
                addcolor(r->rcol, scp->val);
        }
}


srcscatter(r)                   /* compute source scattering into ray */
register RAY  *r;
{
        int  oldsampndx;
        int  nsamps;
        RAY  sr;
        SRCINDEX  si;
        double  t, lastt, d;
        COLOR  cumval, ctmp;
        int  i, j;

        if (r->slights == NULL || r->slights[0] == 0 || r->gecc >= 1.-FTINY)
                return;
        if (ssampdist <= FTINY || (nsamps = r->rot/ssampdist + .5) < 1)
                nsamps = 1;
        oldsampndx = samplendx;
        samplendx = random()&0x7fff;            /* randomize */
        for (i = r->slights[0]; i > 0; i--) {   /* for each source */
                setcolor(cumval, 0., 0., 0.);
                lastt = r->rot;
                for (j = nsamps; j-- > 0; ) {   /* for each sample position */
                        samplendx++;
                        t = r->rot * (j+frandom())/nsamps;
                        sr.rorg[0] = r->rorg[0] + r->rdir[0]*t;
                        sr.rorg[1] = r->rorg[1] + r->rdir[1]*t;
                        sr.rorg[2] = r->rorg[2] + r->rdir[2]*t;
                        sr.rmax = 0.;
                        initsrcindex(&si);      /* sample ray to this source */
                        si.sn = r->slights[i];
                        nopart(&si, &sr);
                        if (!srcray(&sr, NULL, &si) ||
                                        sr.rsrc != r->slights[i])
                                continue;               /* no path */
                        copycolor(sr.cext, r->cext);
                        sr.albedo = r->albedo;
                        sr.gecc = r->gecc;
                        rayvalue(&sr);                  /* eval. source ray */
                        if (bright(sr.rcol) <= FTINY)
                                continue;
                                                        /* compute fall-off */
                        d = lastt - t;
                        setcolor(ctmp,  1.-d*colval(r->cext,RED),
                                        1.-d*colval(r->cext,GRN),
                                        1.-d*colval(r->cext,BLU));
                        multcolor(cumval, ctmp);
                        lastt = t;
                        if (r->gecc <= FTINY)           /* compute P(theta) */
                                d = 1.;
                        else {
                                d = DOT(r->rdir, sr.rdir);
                                d = sqrt(1. + r->gecc*r->gecc - 2.*r->gecc*d);
                                d = (1. - r->gecc*r->gecc) / (d*d*d);
                        }
                                                        /* other factors */
                        d *= si.dom * r->albedo * r->rot / (4.*PI*nsamps);
                        multcolor(sr.rcol, r->cext);
                        scalecolor(sr.rcol, d);
                        addcolor(cumval, sr.rcol);
                }
                                                /* final fall-off */
                setcolor(ctmp,  1.-lastt*colval(r->cext,RED),
                                1.-lastt*colval(r->cext,GRN),
                                1.-lastt*colval(r->cext,BLU));
                multcolor(cumval, ctmp);
                addcolor(r->rcol, cumval);      /* sum into ray result */
        }
        samplendx = oldsampndx;
}


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

/* illumblock *
 *
 * 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.
 * We also prevent an illum from passing to a glow; this provides a
 * convenient mechanism for defining detailed light source
 * geometry behind (or inside) an effective radiator.
 */

static int weaksrcmod(obj) int obj;     /* efficiency booster function */
{register OBJREC *o = objptr(obj);
return(o->otype==MAT_ILLUM|o->otype==MAT_GLOW);}

#define  illumblock(m, r)       (!(source[r->rsrc].sflags&SVIRTUAL) && \
                                r->rod > 0.0 && \
                                weaksrcmod(source[r->rsrc].so->omod))

/* 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 that should be passed.
 */

#define  wrongsource(m, r)      (r->rsrc>=0 && source[r->rsrc].so!=r->ro && \
                                (m->otype!=MAT_ILLUM || illumblock(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.
 * (Glows with negative radii should NEVER participate in illumination.)
 */

#define  distglow(m, r, d)      (m->otype==MAT_GLOW && \
                                m->oargs.farg[3] >= -FTINY && \
                                d > 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 || \
                /* not 100% correct */  distglow(m, r, r->rot)))

/* 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 -dv flag is normally on for sources to be visible.
 */

#define  srcignore(m, r)        !(directvis || r->crtype&SHADOW || \
                                distglow(m, r, raydist(r,PRIMARY)))


m_light(m, r)                   /* ray hit a light source */
register OBJREC  *m;
register RAY  *r;
{
                                                /* check for over-counting */
        if (badcomponent(m, r))
                return(1);
        if (wrongsource(m, r))
                return(1);
                                                /* check for passed illum */
        if (passillum(m, r)) {
                if (m->oargs.nsargs && strcmp(m->oargs.sarg[0], VOIDID))
                        return(rayshade(r, modifier(m->oargs.sarg[0])));
                raytrans(r);
                return(1);
        }
                                        /* otherwise treat as source */
                                                /* check for behind */
        if (r->rod < 0.0)
                return(1);
                                                /* check for invisibility */
        if (srcignore(m, r))
                return(1);
                                                /* check for outside spot */
        if (m->otype==MAT_SPOT && spotout(r, makespot(m)))
                return(1);
                                                /* 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);
        return(1);
}
Revision:	2.21
Committed:	Mon Dec 11 15:00:24 1995 UTC (28 years, 4 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.20:	+6 -10 lines
Log Message:	fixed bug in srcscatter() for source subsampling
#	User	Rev	Content
1	greg	2.17	/* Copyright (c) 1995 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	2.19	#include "random.h"
22
23			extern double ssampdist; /* scatter sampling distance */
24
25	greg	1.35	/*
26			* Structures used by direct()
27			*/
28	greg	1.1
29	greg	1.35	typedef struct {
30	greg	1.45	int sno; /* source number */
31	greg	1.35	FVECT dir; /* source direction */
32			COLOR coef; /* material coefficient */
33			COLOR val; /* contribution */
34			} CONTRIB; /* direct contribution */
35	greg	1.1
36	greg	1.35	typedef struct {
37	greg	1.45	int sndx; /* source index (to CONTRIB array) */
38	greg	1.35	float brt; /* brightness (for comparison) */
39			} CNTPTR; /* contribution pointer */
40	greg	1.1
41	greg	1.25	static CONTRIB srccnt; / source contributions in direct() */
42			static CNTPTR cntord; / source ordering in direct() */
43	greg	1.45	static int maxcntr = 0; /* size of contribution arrays */
44	greg	1.1
45	greg	1.25
46	greg	1.1	marksources() /* find and mark source objects */
47			{
48	greg	2.3	int foundsource = 0;
49	greg	1.33	int i;
50	greg	1.1	register OBJREC o, m;
51	greg	1.36	register int ns;
52	greg	1.35	/* initialize dispatch table */
53			initstypes();
54			/* find direct sources */
55	greg	1.1	for (i = 0; i < nobjects; i++) {
56
57			o = objptr(i);
58
59	greg	1.35	if (!issurface(o->otype) \|\| o->omod == OVOID)
60	greg	1.1	continue;
61
62			m = objptr(o->omod);
63
64	greg	1.24	if (!islight(m->otype))
65	greg	1.1	continue;
66
67	greg	1.6	if (m->oargs.nfargs != (m->otype == MAT_GLOW ? 4 :
68			m->otype == MAT_SPOT ? 7 : 3))
69	greg	1.1	objerror(m, USER, "bad # arguments");
70
71	greg	1.6	if (m->otype == MAT_GLOW &&
72			o->otype != OBJ_SOURCE &&
73			m->oargs.farg[3] <= FTINY)
74	greg	1.1	continue; /* don't bother */
75	greg	2.16	if (m->oargs.farg[0] <= FTINY && m->oargs.farg[1] <= FTINY &&
76			m->oargs.farg[2] <= FTINY)
77			continue; /* don't bother */
78	greg	1.1
79	greg	1.35	if (sfun[o->otype].of == NULL \|\|
80			sfun[o->otype].of->setsrc == NULL)
81			objerror(o, USER, "illegal material");
82
83	greg	1.36	if ((ns = newsource()) < 0)
84	greg	1.25	goto memerr;
85	greg	1.1
86	greg	1.37	setsource(&source[ns], o);
87	greg	1.1
88	greg	1.6	if (m->otype == MAT_GLOW) {
89	greg	1.36	source[ns].sflags \|= SPROX;
90			source[ns].sl.prox = m->oargs.farg[3];
91	greg	2.8	if (source[ns].sflags & SDISTANT)
92	greg	1.36	source[ns].sflags \|= SSKIP;
93	greg	1.6	} else if (m->otype == MAT_SPOT) {
94	greg	1.36	source[ns].sflags \|= SSPOT;
95			if ((source[ns].sl.s = makespot(m)) == NULL)
96	greg	1.33	goto memerr;
97	greg	1.38	if (source[ns].sflags & SFLAT &&
98			!checkspot(source[ns].sl.s,source[ns].snorm)) {
99			objerror(o, WARNING,
100			"invalid spotlight direction");
101			source[ns].sflags \|= SSKIP;
102			}
103	greg	1.6	}
104	greg	2.3	if (!(source[ns].sflags & SSKIP))
105			foundsource++;
106	greg	1.1	}
107	greg	2.3	if (!foundsource) {
108	greg	1.25	error(WARNING, "no light sources found");
109			return;
110			}
111	greg	1.33	markvirtuals(); /* find and add virtual sources */
112	greg	1.45	/* allocate our contribution arrays */
113	greg	1.48	maxcntr = nsources + MAXSPART; /* start with this many */
114	greg	1.45	srccnt = (CONTRIB )malloc(maxcntrsizeof(CONTRIB));
115			cntord = (CNTPTR )malloc(maxcntrsizeof(CNTPTR));
116	greg	1.48	if (srccnt == NULL \| cntord == NULL)
117	greg	1.33	goto memerr;
118			return;
119	greg	1.25	memerr:
120			error(SYSTEM, "out of memory in marksources");
121	greg	1.1	}
122
123
124	greg	1.45	srcray(sr, r, si) /* send a ray to a source, return domega */
125	greg	1.1	register RAY sr; / returned source ray */
126			RAY r; / ray which hit object */
127	greg	1.45	SRCINDEX si; / source sample index */
128	greg	1.1	{
129	greg	1.45	double d; /* distance to source */
130			register SRCREC *srcp;
131	greg	1.1
132	greg	1.45	rayorigin(sr, r, SHADOW, 1.0); /* ignore limits */
133	greg	1.1
134	greg	1.47	while ((d = nextssamp(sr, si)) != 0.0) {
135	greg	1.45	sr->rsrc = si->sn; /* remember source */
136			srcp = source + si->sn;
137			if (srcp->sflags & SDISTANT) {
138	greg	2.18	if (srcp->sflags & SSPOT && spotout(sr, srcp->sl.s))
139	greg	2.4	continue;
140	greg	1.45	return(1); /* sample OK */
141	greg	1.40	}
142	greg	1.45	/* local source */
143	greg	1.6	/* check proximity */
144	greg	1.45	if (srcp->sflags & SPROX && d > srcp->sl.prox)
145			continue;
146	greg	1.6	/* check angle */
147	greg	1.45	if (srcp->sflags & SSPOT) {
148	greg	2.18	if (spotout(sr, srcp->sl.s))
149	greg	1.45	continue;
150			/* adjust solid angle */
151			si->dom = dd;
152			d += srcp->sl.s->flen;
153			si->dom /= d*d;
154	greg	1.1	}
155	greg	1.45	return(1); /* sample OK */
156			}
157			return(0); /* no more samples */
158	greg	1.1	}
159
160
161	greg	1.35	srcvalue(r) /* punch ray to source and compute value */
162	greg	2.15	register RAY *r;
163	greg	1.1	{
164	greg	1.35	register SRCREC *sp;
165	greg	1.1
166	greg	1.35	sp = &source[r->rsrc];
167			if (sp->sflags & SVIRTUAL) { /* virtual source */
168			/* check intersection */
169			if (!(*ofun[sp->so->otype].funp)(sp->so, r))
170			return;
171	greg	2.15	if (!rayshade(r, r->ro->omod)) /* compute contribution */
172			goto nomat;
173	greg	2.19	rayparticipate(r);
174	greg	1.35	return;
175	greg	1.1	}
176	greg	1.35	/* compute intersection */
177			if (sp->sflags & SDISTANT ? sourcehit(r) :
178			(*ofun[sp->so->otype].funp)(sp->so, r)) {
179			if (sp->sa.success >= 0)
180			sp->sa.success++;
181	greg	2.15	if (!rayshade(r, r->ro->omod)) /* compute contribution */
182			goto nomat;
183	greg	2.19	rayparticipate(r);
184	greg	1.35	return;
185	greg	1.1	}
186	greg	2.15	/* we missed our mark! */
187	greg	1.35	if (sp->sa.success < 0)
188			return; /* bitched already */
189			sp->sa.success -= AIMREQT;
190			if (sp->sa.success >= 0)
191			return; /* leniency */
192			sprintf(errmsg, "aiming failure for light source \"%s\"",
193			sp->so->oname);
194			error(WARNING, errmsg); /* issue warning */
195	greg	2.15	return;
196			nomat:
197			objerror(r->ro, USER, "material not found");
198	greg	1.1	}
199
200
201	greg	2.5	sourcehit(r) /* check to see if ray hit distant source */
202			register RAY *r;
203			{
204			int first, last;
205			register int i;
206
207			if (r->rsrc >= 0) { /* check only one if aimed */
208			first = last = r->rsrc;
209			} else { /* otherwise check all */
210			first = 0; last = nsources-1;
211			}
212			for (i = first; i <= last; i++)
213			if ((source[i].sflags & (SDISTANT\|SVIRTUAL)) == SDISTANT)
214			/*
215			* Check to see if ray is within
216			* solid angle of source.
217			*/
218			if (2.0PI (1.0 - DOT(source[i].sloc,r->rdir))
219			<= source[i].ss2) {
220			r->ro = source[i].so;
221			if (!(source[i].sflags & SSKIP))
222			break;
223			}
224
225			if (r->ro != NULL) {
226			for (i = 0; i < 3; i++)
227			r->ron[i] = -r->rdir[i];
228			r->rod = 1.0;
229			r->rox = NULL;
230			return(1);
231			}
232			return(0);
233			}
234
235
236	greg	1.4	static int
237			cntcmp(sc1, sc2) /* contribution compare (descending) */
238	greg	1.9	register CNTPTR sc1, sc2;
239	greg	1.4	{
240			if (sc1->brt > sc2->brt)
241			return(-1);
242			if (sc1->brt < sc2->brt)
243			return(1);
244			return(0);
245			}
246
247
248			direct(r, f, p) /* add direct component */
249			RAY r; / ray that hit surface */
250			int (f)(); / direct component coefficient function */
251			char p; / data for f */
252			{
253	greg	1.42	extern int (*trace)();
254	greg	1.4	register int sn;
255	greg	2.7	register CONTRIB *scp;
256	greg	1.45	SRCINDEX si;
257	greg	1.12	int nshadcheck, ncnts;
258	greg	1.29	int nhits;
259	greg	1.45	double prob, ourthresh, hwt;
260	greg	1.4	RAY sr;
261	greg	1.25	/* NOTE: srccnt and cntord global so no recursion */
262	greg	1.22	if (nsources <= 0)
263	greg	1.25	return; /* no sources?! */
264	greg	1.4	/* potential contributions */
265	greg	1.45	initsrcindex(&si);
266			for (sn = 0; srcray(&sr, r, &si); sn++) {
267			if (sn >= maxcntr) {
268			maxcntr = sn + MAXSPART;
269			srccnt = (CONTRIB )realloc((char )srccnt,
270			maxcntr*sizeof(CONTRIB));
271			cntord = (CNTPTR )realloc((char )cntord,
272			maxcntr*sizeof(CNTPTR));
273	greg	1.48	if (srccnt == NULL \| cntord == NULL)
274	greg	1.45	error(SYSTEM, "out of memory in direct");
275			}
276			cntord[sn].sndx = sn;
277	greg	2.7	scp = srccnt + sn;
278			scp->sno = sr.rsrc;
279	greg	1.4	/* compute coefficient */
280	greg	2.7	(*f)(scp->coef, p, sr.rdir, si.dom);
281			cntord[sn].brt = bright(scp->coef);
282	greg	1.15	if (cntord[sn].brt <= 0.0)
283	greg	1.4	continue;
284	greg	2.7	VCOPY(scp->dir, sr.rdir);
285	greg	1.35	/* compute potential */
286			sr.revf = srcvalue;
287			rayvalue(&sr);
288	greg	2.7	copycolor(scp->val, sr.rcol);
289			multcolor(scp->val, scp->coef);
290			cntord[sn].brt = bright(scp->val);
291	greg	1.4	}
292			/* sort contributions */
293	greg	1.45	qsort(cntord, sn, sizeof(CNTPTR), cntcmp);
294	greg	1.13	{ /* find last */
295			register int l, m;
296
297	greg	1.45	ncnts = l = sn;
298			sn = 0;
299	greg	1.13	while ((m = (sn + ncnts) >> 1) != l) {
300			if (cntord[m].brt > 0.0)
301			sn = m;
302			else
303			ncnts = m;
304			l = m;
305			}
306			}
307	greg	2.2	if (ncnts == 0)
308			return; /* no contributions! */
309	greg	1.12	/* accumulate tail */
310			for (sn = ncnts-1; sn > 0; sn--)
311			cntord[sn-1].brt += cntord[sn].brt;
312	greg	1.45	/* compute number to check */
313			nshadcheck = pow((double)ncnts, shadcert) + .5;
314			/* modify threshold */
315			ourthresh = shadthresh / r->rweight;
316	greg	1.10	/* test for shadows */
317	greg	2.13	for (nhits = 0, hwt = 0.0, sn = 0; sn < ncnts;
318			hwt += (double)source[scp->sno].nhits /
319			(double)source[scp->sno].ntests,
320			sn++) {
321	greg	1.10	/* check threshold */
322	greg	1.12	if ((sn+nshadcheck>=ncnts ? cntord[sn].brt :
323	greg	1.27	cntord[sn].brt-cntord[sn+nshadcheck].brt)
324			< ourthresh*bright(r->rcol))
325	greg	1.4	break;
326	greg	2.7	scp = srccnt + cntord[sn].sndx;
327	greg	1.4	/* test for hit */
328			rayorigin(&sr, r, SHADOW, 1.0);
329	greg	2.7	VCOPY(sr.rdir, scp->dir);
330			sr.rsrc = scp->sno;
331			source[scp->sno].ntests++; /* keep statistics */
332	greg	1.4	if (localhit(&sr, &thescene) &&
333	greg	2.7	( sr.ro != source[scp->sno].so \|\|
334			source[scp->sno].sflags & SFOLLOW )) {
335	greg	1.33	/* follow entire path */
336	greg	2.15	if (!raycont(&sr))
337			objerror(sr.ro, USER, "material not found");
338	greg	2.19	rayparticipate(&sr);
339	greg	1.42	if (trace != NULL)
340			(trace)(&sr); / trace execution */
341	greg	1.5	if (bright(sr.rcol) <= FTINY)
342	greg	1.4	continue; /* missed! */
343	greg	2.7	copycolor(scp->val, sr.rcol);
344			multcolor(scp->val, scp->coef);
345	greg	1.4	}
346			/* add contribution if hit */
347	greg	2.7	addcolor(r->rcol, scp->val);
348	greg	1.29	nhits++;
349	greg	2.7	source[scp->sno].nhits++;
350	greg	1.4	}
351	greg	2.13	/* source hit rate */
352			if (hwt > FTINY)
353			hwt = (double)nhits / hwt;
354	greg	1.29	else
355			hwt = 0.5;
356	greg	1.20	#ifdef DEBUG
357	greg	2.13	sprintf(errmsg, "%d tested, %d untested, %f conditional hit rate\n",
358	greg	1.12	sn, ncnts-sn, hwt);
359			eputs(errmsg);
360	greg	1.4	#endif
361			/* add in untested sources */
362	greg	1.12	for ( ; sn < ncnts; sn++) {
363	greg	2.7	scp = srccnt + cntord[sn].sndx;
364			prob = hwt * (double)source[scp->sno].nhits /
365			(double)source[scp->sno].ntests;
366	greg	2.13	if (prob > 1.0)
367			prob = 1.0;
368	greg	2.7	scalecolor(scp->val, prob);
369			addcolor(r->rcol, scp->val);
370	greg	2.19	}
371			}
372
373
374			srcscatter(r) /* compute source scattering into ray */
375			register RAY *r;
376			{
377	greg	2.20	int oldsampndx;
378	greg	2.19	int nsamps;
379			RAY sr;
380			SRCINDEX si;
381			double t, lastt, d;
382			COLOR cumval, ctmp;
383			int i, j;
384
385			if (r->slights == NULL \|\| r->slights[0] == 0 \|\| r->gecc >= 1.-FTINY)
386			return;
387			if (ssampdist <= FTINY \|\| (nsamps = r->rot/ssampdist + .5) < 1)
388			nsamps = 1;
389	greg	2.20	oldsampndx = samplendx;
390			samplendx = random()&0x7fff; /* randomize */
391	greg	2.19	for (i = r->slights[0]; i > 0; i--) { /* for each source */
392			setcolor(cumval, 0., 0., 0.);
393			lastt = r->rot;
394			for (j = nsamps; j-- > 0; ) { /* for each sample position */
395			samplendx++;
396			t = r->rot * (j+frandom())/nsamps;
397			sr.rorg[0] = r->rorg[0] + r->rdir[0]*t;
398			sr.rorg[1] = r->rorg[1] + r->rdir[1]*t;
399			sr.rorg[2] = r->rorg[2] + r->rdir[2]*t;
400			sr.rmax = 0.;
401	greg	2.21	initsrcindex(&si); /* sample ray to this source */
402			si.sn = r->slights[i];
403			nopart(&si, &sr);
404			if (!srcray(&sr, NULL, &si) \|\|
405			sr.rsrc != r->slights[i])
406			continue; /* no path */
407	greg	2.19	copycolor(sr.cext, r->cext);
408			sr.albedo = r->albedo;
409			sr.gecc = r->gecc;
410			rayvalue(&sr); /* eval. source ray */
411			if (bright(sr.rcol) <= FTINY)
412			continue;
413			/* compute fall-off */
414			d = lastt - t;
415			setcolor(ctmp, 1.-d*colval(r->cext,RED),
416			1.-d*colval(r->cext,GRN),
417			1.-d*colval(r->cext,BLU));
418			multcolor(cumval, ctmp);
419			lastt = t;
420			if (r->gecc <= FTINY) /* compute P(theta) */
421			d = 1.;
422			else {
423			d = DOT(r->rdir, sr.rdir);
424			d = sqrt(1. + r->geccr->gecc - 2.r->gecc*d);
425			d = (1. - r->geccr->gecc) / (dd*d);
426			}
427			/* other factors */
428			d = si.dom r->albedo * r->rot / (4.PInsamps);
429			multcolor(sr.rcol, r->cext);
430			scalecolor(sr.rcol, d);
431			addcolor(cumval, sr.rcol);
432			}
433			/* final fall-off */
434			setcolor(ctmp, 1.-lastt*colval(r->cext,RED),
435			1.-lastt*colval(r->cext,GRN),
436			1.-lastt*colval(r->cext,BLU));
437			multcolor(cumval, ctmp);
438			addcolor(r->rcol, cumval); /* sum into ray result */
439	greg	1.1	}
440	greg	2.20	samplendx = oldsampndx;
441	greg	2.4	}
442
443
444			/****************************************************************
445			* The following macros were separated from the m_light() routine
446			* because they are very nasty and difficult to understand.
447			*/
448
449	greg	2.11	/* illumblock *
450	greg	2.4	*
451			* We cannot allow an illum to pass to another illum, because that
452			* would almost certainly constitute overcounting.
453			* However, we do allow an illum to pass to another illum
454			* that is actually going to relay to a virtual light source.
455	greg	2.11	* We also prevent an illum from passing to a glow; this provides a
456			* convenient mechanism for defining detailed light source
457			* geometry behind (or inside) an effective radiator.
458	greg	2.4	*/
459
460	greg	2.11	static int weaksrcmod(obj) int obj; /* efficiency booster function */
461			{register OBJREC *o = objptr(obj);
462			return(o->otype==MAT_ILLUM\|o->otype==MAT_GLOW);}
463	greg	2.4
464	greg	2.11	#define illumblock(m, r) (!(source[r->rsrc].sflags&SVIRTUAL) && \
465	greg	2.12	r->rod > 0.0 && \
466	greg	2.11	weaksrcmod(source[r->rsrc].so->omod))
467
468	greg	2.4	/* wrongsource *
469			*
470			* This source is the wrong source (ie. overcounted) if we are
471			* aimed to a different source than the one we hit and the one
472	greg	2.11	* we hit is not an illum that should be passed.
473	greg	2.4	*/
474
475			#define wrongsource(m, r) (r->rsrc>=0 && source[r->rsrc].so!=r->ro && \
476	greg	2.11	(m->otype!=MAT_ILLUM \|\| illumblock(m,r)))
477	greg	2.4
478			/* distglow *
479			*
480			* A distant glow is an object that sometimes acts as a light source,
481			* but is too far away from the test point to be one in this case.
482	greg	2.11	* (Glows with negative radii should NEVER participate in illumination.)
483	greg	2.4	*/
484
485	greg	2.17	#define distglow(m, r, d) (m->otype==MAT_GLOW && \
486	greg	2.10	m->oargs.farg[3] >= -FTINY && \
487	greg	2.17	d > m->oargs.farg[3])
488	greg	2.4
489			/* badcomponent *
490			*
491			* We must avoid counting light sources in the ambient calculation,
492			* since the direct component is handled separately. Therefore, any
493			* ambient ray which hits an active light source must be discarded.
494			* The same is true for stray specular samples, since the specular
495			* contribution from light sources is calculated separately.
496			*/
497
498			#define badcomponent(m, r) (r->crtype&(AMBIENT\|SPECULAR) && \
499			!(r->crtype&SHADOW \|\| r->rod < 0.0 \|\| \
500	greg	2.17	/* not 100% correct */ distglow(m, r, r->rot)))
501	greg	2.4
502			/* passillum *
503			*
504			* An illum passes to another material type when we didn't hit it
505			* on purpose (as part of a direct calculation), or it is relaying
506			* a virtual light source.
507			*/
508
509			#define passillum(m, r) (m->otype==MAT_ILLUM && \
510			(r->rsrc<0 \|\| source[r->rsrc].so!=r->ro \|\| \
511			source[r->rsrc].sflags&SVIRTUAL))
512
513			/* srcignore *
514			*
515	greg	2.10	* The -dv flag is normally on for sources to be visible.
516	greg	2.4	*/
517
518	greg	2.17	#define srcignore(m, r) !(directvis \|\| r->crtype&SHADOW \|\| \
519			distglow(m, r, raydist(r,PRIMARY)))
520	greg	2.4
521
522			m_light(m, r) /* ray hit a light source */
523			register OBJREC *m;
524			register RAY *r;
525			{
526			/* check for over-counting */
527	greg	2.12	if (badcomponent(m, r))
528	greg	2.14	return(1);
529	greg	2.17	if (wrongsource(m, r))
530	greg	2.14	return(1);
531	greg	2.4	/* check for passed illum */
532			if (passillum(m, r)) {
533	greg	2.14	if (m->oargs.nsargs && strcmp(m->oargs.sarg[0], VOIDID))
534			return(rayshade(r, modifier(m->oargs.sarg[0])));
535			raytrans(r);
536			return(1);
537	greg	2.4	}
538			/* otherwise treat as source */
539			/* check for behind */
540			if (r->rod < 0.0)
541	greg	2.14	return(1);
542	greg	2.4	/* check for invisibility */
543			if (srcignore(m, r))
544	greg	2.14	return(1);
545	greg	2.4	/* check for outside spot */
546	greg	2.18	if (m->otype==MAT_SPOT && spotout(r, makespot(m)))
547	greg	2.14	return(1);
548	greg	2.4	/* get distribution pattern */
549			raytexture(r, m->omod);
550			/* get source color */
551			setcolor(r->rcol, m->oargs.farg[0],
552			m->oargs.farg[1],
553			m->oargs.farg[2]);
554			/* modify value */
555			multcolor(r->rcol, r->pcol);
556	greg	2.14	return(1);
557	greg	1.1	}