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"

/*
 * 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;
                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;
                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");
                        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);
        }
}


/****************************************************************
 * 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:	2.18
Committed:	Tue Nov 7 12:40:32 1995 UTC (28 years, 5 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.17:	+3 -3 lines
Log Message:	changed spotlight struct so flen<0 for distant sources
#	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	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	greg	2.16	if (m->oargs.farg[0] <= FTINY && m->oargs.farg[1] <= FTINY &&
72			m->oargs.farg[2] <= FTINY)
73			continue; /* don't bother */
74	greg	1.1
75	greg	1.35	if (sfun[o->otype].of == NULL \|\|
76			sfun[o->otype].of->setsrc == NULL)
77			objerror(o, USER, "illegal material");
78
79	greg	1.36	if ((ns = newsource()) < 0)
80	greg	1.25	goto memerr;
81	greg	1.1
82	greg	1.37	setsource(&source[ns], o);
83	greg	1.1
84	greg	1.6	if (m->otype == MAT_GLOW) {
85	greg	1.36	source[ns].sflags \|= SPROX;
86			source[ns].sl.prox = m->oargs.farg[3];
87	greg	2.8	if (source[ns].sflags & SDISTANT)
88	greg	1.36	source[ns].sflags \|= SSKIP;
89	greg	1.6	} else if (m->otype == MAT_SPOT) {
90	greg	1.36	source[ns].sflags \|= SSPOT;
91			if ((source[ns].sl.s = makespot(m)) == NULL)
92	greg	1.33	goto memerr;
93	greg	1.38	if (source[ns].sflags & SFLAT &&
94			!checkspot(source[ns].sl.s,source[ns].snorm)) {
95			objerror(o, WARNING,
96			"invalid spotlight direction");
97			source[ns].sflags \|= SSKIP;
98			}
99	greg	1.6	}
100	greg	2.3	if (!(source[ns].sflags & SSKIP))
101			foundsource++;
102	greg	1.1	}
103	greg	2.3	if (!foundsource) {
104	greg	1.25	error(WARNING, "no light sources found");
105			return;
106			}
107	greg	1.33	markvirtuals(); /* find and add virtual sources */
108	greg	1.45	/* allocate our contribution arrays */
109	greg	1.48	maxcntr = nsources + MAXSPART; /* start with this many */
110	greg	1.45	srccnt = (CONTRIB )malloc(maxcntrsizeof(CONTRIB));
111			cntord = (CNTPTR )malloc(maxcntrsizeof(CNTPTR));
112	greg	1.48	if (srccnt == NULL \| cntord == NULL)
113	greg	1.33	goto memerr;
114			return;
115	greg	1.25	memerr:
116			error(SYSTEM, "out of memory in marksources");
117	greg	1.1	}
118
119
120	greg	1.45	srcray(sr, r, si) /* send a ray to a source, return domega */
121	greg	1.1	register RAY sr; / returned source ray */
122			RAY r; / ray which hit object */
123	greg	1.45	SRCINDEX si; / source sample index */
124	greg	1.1	{
125	greg	1.45	double d; /* distance to source */
126			register SRCREC *srcp;
127	greg	1.1
128	greg	1.45	rayorigin(sr, r, SHADOW, 1.0); /* ignore limits */
129	greg	1.1
130	greg	1.47	while ((d = nextssamp(sr, si)) != 0.0) {
131	greg	1.45	sr->rsrc = si->sn; /* remember source */
132			srcp = source + si->sn;
133			if (srcp->sflags & SDISTANT) {
134	greg	2.18	if (srcp->sflags & SSPOT && spotout(sr, srcp->sl.s))
135	greg	2.4	continue;
136	greg	1.45	return(1); /* sample OK */
137	greg	1.40	}
138	greg	1.45	/* local source */
139	greg	1.6	/* check proximity */
140	greg	1.45	if (srcp->sflags & SPROX && d > srcp->sl.prox)
141			continue;
142	greg	1.6	/* check angle */
143	greg	1.45	if (srcp->sflags & SSPOT) {
144	greg	2.18	if (spotout(sr, srcp->sl.s))
145	greg	1.45	continue;
146			/* adjust solid angle */
147			si->dom = dd;
148			d += srcp->sl.s->flen;
149			si->dom /= d*d;
150	greg	1.1	}
151	greg	1.45	return(1); /* sample OK */
152			}
153			return(0); /* no more samples */
154	greg	1.1	}
155
156
157	greg	1.35	srcvalue(r) /* punch ray to source and compute value */
158	greg	2.15	register RAY *r;
159	greg	1.1	{
160	greg	1.35	register SRCREC *sp;
161	greg	1.1
162	greg	1.35	sp = &source[r->rsrc];
163			if (sp->sflags & SVIRTUAL) { /* virtual source */
164			/* check intersection */
165			if (!(*ofun[sp->so->otype].funp)(sp->so, r))
166			return;
167	greg	2.15	if (!rayshade(r, r->ro->omod)) /* compute contribution */
168			goto nomat;
169	greg	1.35	return;
170	greg	1.1	}
171	greg	1.35	/* compute intersection */
172			if (sp->sflags & SDISTANT ? sourcehit(r) :
173			(*ofun[sp->so->otype].funp)(sp->so, r)) {
174			if (sp->sa.success >= 0)
175			sp->sa.success++;
176	greg	2.15	if (!rayshade(r, r->ro->omod)) /* compute contribution */
177			goto nomat;
178	greg	1.35	return;
179	greg	1.1	}
180	greg	2.15	/* we missed our mark! */
181	greg	1.35	if (sp->sa.success < 0)
182			return; /* bitched already */
183			sp->sa.success -= AIMREQT;
184			if (sp->sa.success >= 0)
185			return; /* leniency */
186			sprintf(errmsg, "aiming failure for light source \"%s\"",
187			sp->so->oname);
188			error(WARNING, errmsg); /* issue warning */
189	greg	2.15	return;
190			nomat:
191			objerror(r->ro, USER, "material not found");
192	greg	1.1	}
193
194
195	greg	2.5	sourcehit(r) /* check to see if ray hit distant source */
196			register RAY *r;
197			{
198			int first, last;
199			register int i;
200
201			if (r->rsrc >= 0) { /* check only one if aimed */
202			first = last = r->rsrc;
203			} else { /* otherwise check all */
204			first = 0; last = nsources-1;
205			}
206			for (i = first; i <= last; i++)
207			if ((source[i].sflags & (SDISTANT\|SVIRTUAL)) == SDISTANT)
208			/*
209			* Check to see if ray is within
210			* solid angle of source.
211			*/
212			if (2.0PI (1.0 - DOT(source[i].sloc,r->rdir))
213			<= source[i].ss2) {
214			r->ro = source[i].so;
215			if (!(source[i].sflags & SSKIP))
216			break;
217			}
218
219			if (r->ro != NULL) {
220			for (i = 0; i < 3; i++)
221			r->ron[i] = -r->rdir[i];
222			r->rod = 1.0;
223			r->rox = NULL;
224			return(1);
225			}
226			return(0);
227			}
228
229
230	greg	1.4	static int
231			cntcmp(sc1, sc2) /* contribution compare (descending) */
232	greg	1.9	register CNTPTR sc1, sc2;
233	greg	1.4	{
234			if (sc1->brt > sc2->brt)
235			return(-1);
236			if (sc1->brt < sc2->brt)
237			return(1);
238			return(0);
239			}
240
241
242			direct(r, f, p) /* add direct component */
243			RAY r; / ray that hit surface */
244			int (f)(); / direct component coefficient function */
245			char p; / data for f */
246			{
247	greg	1.42	extern int (*trace)();
248	greg	1.4	register int sn;
249	greg	2.7	register CONTRIB *scp;
250	greg	1.45	SRCINDEX si;
251	greg	1.12	int nshadcheck, ncnts;
252	greg	1.29	int nhits;
253	greg	1.45	double prob, ourthresh, hwt;
254	greg	1.4	RAY sr;
255	greg	1.25	/* NOTE: srccnt and cntord global so no recursion */
256	greg	1.22	if (nsources <= 0)
257	greg	1.25	return; /* no sources?! */
258	greg	1.4	/* potential contributions */
259	greg	1.45	initsrcindex(&si);
260			for (sn = 0; srcray(&sr, r, &si); sn++) {
261			if (sn >= maxcntr) {
262			maxcntr = sn + MAXSPART;
263			srccnt = (CONTRIB )realloc((char )srccnt,
264			maxcntr*sizeof(CONTRIB));
265			cntord = (CNTPTR )realloc((char )cntord,
266			maxcntr*sizeof(CNTPTR));
267	greg	1.48	if (srccnt == NULL \| cntord == NULL)
268	greg	1.45	error(SYSTEM, "out of memory in direct");
269			}
270			cntord[sn].sndx = sn;
271	greg	2.7	scp = srccnt + sn;
272			scp->sno = sr.rsrc;
273	greg	1.4	/* compute coefficient */
274	greg	2.7	(*f)(scp->coef, p, sr.rdir, si.dom);
275			cntord[sn].brt = bright(scp->coef);
276	greg	1.15	if (cntord[sn].brt <= 0.0)
277	greg	1.4	continue;
278	greg	2.7	VCOPY(scp->dir, sr.rdir);
279	greg	1.35	/* compute potential */
280			sr.revf = srcvalue;
281			rayvalue(&sr);
282	greg	2.7	copycolor(scp->val, sr.rcol);
283			multcolor(scp->val, scp->coef);
284			cntord[sn].brt = bright(scp->val);
285	greg	1.4	}
286			/* sort contributions */
287	greg	1.45	qsort(cntord, sn, sizeof(CNTPTR), cntcmp);
288	greg	1.13	{ /* find last */
289			register int l, m;
290
291	greg	1.45	ncnts = l = sn;
292			sn = 0;
293	greg	1.13	while ((m = (sn + ncnts) >> 1) != l) {
294			if (cntord[m].brt > 0.0)
295			sn = m;
296			else
297			ncnts = m;
298			l = m;
299			}
300			}
301	greg	2.2	if (ncnts == 0)
302			return; /* no contributions! */
303	greg	1.12	/* accumulate tail */
304			for (sn = ncnts-1; sn > 0; sn--)
305			cntord[sn-1].brt += cntord[sn].brt;
306	greg	1.45	/* compute number to check */
307			nshadcheck = pow((double)ncnts, shadcert) + .5;
308			/* modify threshold */
309			ourthresh = shadthresh / r->rweight;
310	greg	1.10	/* test for shadows */
311	greg	2.13	for (nhits = 0, hwt = 0.0, sn = 0; sn < ncnts;
312			hwt += (double)source[scp->sno].nhits /
313			(double)source[scp->sno].ntests,
314			sn++) {
315	greg	1.10	/* check threshold */
316	greg	1.12	if ((sn+nshadcheck>=ncnts ? cntord[sn].brt :
317	greg	1.27	cntord[sn].brt-cntord[sn+nshadcheck].brt)
318			< ourthresh*bright(r->rcol))
319	greg	1.4	break;
320	greg	2.7	scp = srccnt + cntord[sn].sndx;
321	greg	1.4	/* test for hit */
322			rayorigin(&sr, r, SHADOW, 1.0);
323	greg	2.7	VCOPY(sr.rdir, scp->dir);
324			sr.rsrc = scp->sno;
325			source[scp->sno].ntests++; /* keep statistics */
326	greg	1.4	if (localhit(&sr, &thescene) &&
327	greg	2.7	( sr.ro != source[scp->sno].so \|\|
328			source[scp->sno].sflags & SFOLLOW )) {
329	greg	1.33	/* follow entire path */
330	greg	2.15	if (!raycont(&sr))
331			objerror(sr.ro, USER, "material not found");
332	greg	1.42	if (trace != NULL)
333			(trace)(&sr); / trace execution */
334	greg	1.5	if (bright(sr.rcol) <= FTINY)
335	greg	1.4	continue; /* missed! */
336	greg	2.7	copycolor(scp->val, sr.rcol);
337			multcolor(scp->val, scp->coef);
338	greg	1.4	}
339			/* add contribution if hit */
340	greg	2.7	addcolor(r->rcol, scp->val);
341	greg	1.29	nhits++;
342	greg	2.7	source[scp->sno].nhits++;
343	greg	1.4	}
344	greg	2.13	/* source hit rate */
345			if (hwt > FTINY)
346			hwt = (double)nhits / hwt;
347	greg	1.29	else
348			hwt = 0.5;
349	greg	1.20	#ifdef DEBUG
350	greg	2.13	sprintf(errmsg, "%d tested, %d untested, %f conditional hit rate\n",
351	greg	1.12	sn, ncnts-sn, hwt);
352			eputs(errmsg);
353	greg	1.4	#endif
354			/* add in untested sources */
355	greg	1.12	for ( ; sn < ncnts; sn++) {
356	greg	2.7	scp = srccnt + cntord[sn].sndx;
357			prob = hwt * (double)source[scp->sno].nhits /
358			(double)source[scp->sno].ntests;
359	greg	2.13	if (prob > 1.0)
360			prob = 1.0;
361	greg	2.7	scalecolor(scp->val, prob);
362			addcolor(r->rcol, scp->val);
363	greg	1.1	}
364	greg	2.4	}
365
366
367			/****************************************************************
368			* The following macros were separated from the m_light() routine
369			* because they are very nasty and difficult to understand.
370			*/
371
372	greg	2.11	/* illumblock *
373	greg	2.4	*
374			* We cannot allow an illum to pass to another illum, because that
375			* would almost certainly constitute overcounting.
376			* However, we do allow an illum to pass to another illum
377			* that is actually going to relay to a virtual light source.
378	greg	2.11	* We also prevent an illum from passing to a glow; this provides a
379			* convenient mechanism for defining detailed light source
380			* geometry behind (or inside) an effective radiator.
381	greg	2.4	*/
382
383	greg	2.11	static int weaksrcmod(obj) int obj; /* efficiency booster function */
384			{register OBJREC *o = objptr(obj);
385			return(o->otype==MAT_ILLUM\|o->otype==MAT_GLOW);}
386	greg	2.4
387	greg	2.11	#define illumblock(m, r) (!(source[r->rsrc].sflags&SVIRTUAL) && \
388	greg	2.12	r->rod > 0.0 && \
389	greg	2.11	weaksrcmod(source[r->rsrc].so->omod))
390
391	greg	2.4	/* wrongsource *
392			*
393			* This source is the wrong source (ie. overcounted) if we are
394			* aimed to a different source than the one we hit and the one
395	greg	2.11	* we hit is not an illum that should be passed.
396	greg	2.4	*/
397
398			#define wrongsource(m, r) (r->rsrc>=0 && source[r->rsrc].so!=r->ro && \
399	greg	2.11	(m->otype!=MAT_ILLUM \|\| illumblock(m,r)))
400	greg	2.4
401			/* distglow *
402			*
403			* A distant glow is an object that sometimes acts as a light source,
404			* but is too far away from the test point to be one in this case.
405	greg	2.11	* (Glows with negative radii should NEVER participate in illumination.)
406	greg	2.4	*/
407
408	greg	2.17	#define distglow(m, r, d) (m->otype==MAT_GLOW && \
409	greg	2.10	m->oargs.farg[3] >= -FTINY && \
410	greg	2.17	d > m->oargs.farg[3])
411	greg	2.4
412			/* badcomponent *
413			*
414			* We must avoid counting light sources in the ambient calculation,
415			* since the direct component is handled separately. Therefore, any
416			* ambient ray which hits an active light source must be discarded.
417			* The same is true for stray specular samples, since the specular
418			* contribution from light sources is calculated separately.
419			*/
420
421			#define badcomponent(m, r) (r->crtype&(AMBIENT\|SPECULAR) && \
422			!(r->crtype&SHADOW \|\| r->rod < 0.0 \|\| \
423	greg	2.17	/* not 100% correct */ distglow(m, r, r->rot)))
424	greg	2.4
425			/* passillum *
426			*
427			* An illum passes to another material type when we didn't hit it
428			* on purpose (as part of a direct calculation), or it is relaying
429			* a virtual light source.
430			*/
431
432			#define passillum(m, r) (m->otype==MAT_ILLUM && \
433			(r->rsrc<0 \|\| source[r->rsrc].so!=r->ro \|\| \
434			source[r->rsrc].sflags&SVIRTUAL))
435
436			/* srcignore *
437			*
438	greg	2.10	* The -dv flag is normally on for sources to be visible.
439	greg	2.4	*/
440
441	greg	2.17	#define srcignore(m, r) !(directvis \|\| r->crtype&SHADOW \|\| \
442			distglow(m, r, raydist(r,PRIMARY)))
443	greg	2.4
444
445			m_light(m, r) /* ray hit a light source */
446			register OBJREC *m;
447			register RAY *r;
448			{
449			/* check for over-counting */
450	greg	2.12	if (badcomponent(m, r))
451	greg	2.14	return(1);
452	greg	2.17	if (wrongsource(m, r))
453	greg	2.14	return(1);
454	greg	2.4	/* check for passed illum */
455			if (passillum(m, r)) {
456	greg	2.14	if (m->oargs.nsargs && strcmp(m->oargs.sarg[0], VOIDID))
457			return(rayshade(r, modifier(m->oargs.sarg[0])));
458			raytrans(r);
459			return(1);
460	greg	2.4	}
461			/* otherwise treat as source */
462			/* check for behind */
463			if (r->rod < 0.0)
464	greg	2.14	return(1);
465	greg	2.4	/* check for invisibility */
466			if (srcignore(m, r))
467	greg	2.14	return(1);
468	greg	2.4	/* check for outside spot */
469	greg	2.18	if (m->otype==MAT_SPOT && spotout(r, makespot(m)))
470	greg	2.14	return(1);
471	greg	2.4	/* get distribution pattern */
472			raytexture(r, m->omod);
473			/* get source color */
474			setcolor(r->rcol, m->oargs.farg[0],
475			m->oargs.farg[1],
476			m->oargs.farg[2]);
477			/* modify value */
478			multcolor(r->rcol, r->pcol);
479	greg	2.14	return(1);
480	greg	1.1	}