src/rt/source.c

/* Copyright (c) 1990 Regents of the University of California */

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

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

#include  "ray.h"

#include  "octree.h"

#include  "source.h"

#include  "otypes.h"

#include  "cone.h"

#include  "face.h"

#include  "random.h"


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

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

static CONTRIB  *srccnt;                /* source contributions in direct() */
static CNTPTR  *cntord;                 /* source ordering in direct() */


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

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

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

                m = objptr(o->omod);

                if (!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 (source == NULL)
                        source = (SRCREC *)malloc(sizeof(SRCREC));
                else
                        source = (SRCREC *)realloc((char *)source,
                                        (unsigned)(nsources+1)*sizeof(SRCREC));
                if (source == NULL)
                        goto memerr;

                newsource(&source[nsources], o);

                if (m->otype == MAT_GLOW) {
                        source[nsources].sflags |= SPROX;
                        source[nsources].sl.prox = m->oargs.farg[3];
                        if (o->otype == OBJ_SOURCE)
                                source[nsources].sflags |= SSKIP;
                } else if (m->otype == MAT_SPOT) {
                        source[nsources].sflags |= SSPOT;
                        source[nsources].sl.s = makespot(m);
                }
                nsources++;
        }
        if (nsources <= 0) {
                error(WARNING, "no light sources found");
                return;
        }
        srccnt = (CONTRIB *)malloc(nsources*sizeof(CONTRIB));
        cntord = (CNTPTR *)malloc(nsources*sizeof(CNTPTR));
        if (srccnt != NULL && cntord != NULL)
                return;
        /* fall through */
memerr:
        error(SYSTEM, "out of memory in marksources");
}


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

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


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

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


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

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

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

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

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

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

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

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

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

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


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

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

        if (r->ro != NULL) {
                for (i = 0; i < 3; i++)
                        r->ron[i] = -r->rdir[i];
                r->rod = 1.0;
                r->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 double  pow();
        register int  sn;
        int  nshadcheck, ncnts;
        double  prob, ourthresh, hwt, test2, hit2;
        RAY  sr;
                        /* NOTE: srccnt and cntord global so no recursion */
        if (nsources <= 0)
                return;         /* no sources?! */
                                                /* compute number to check */
        nshadcheck = pow((double)nsources, shadcert) + .5;
                                                /* modify threshold */
        ourthresh = shadthresh / r->rweight;
                                                /* potential contributions */
        for (sn = 0; sn < nsources; sn++) {
                cntord[sn].sno = sn;
                cntord[sn].brt = 0.0;
                                                /* get source ray */
                if ((srccnt[sn].dom = srcray(&sr, r, sn)) == 0.0)
                        continue;
                VCOPY(srccnt[sn].dir, sr.rdir);
                                                /* compute coefficient */
                (*f)(srccnt[sn].val, p, srccnt[sn].dir, srccnt[sn].dom);
                cntord[sn].brt = bright(srccnt[sn].val);
                if (cntord[sn].brt <= 0.0)
                        continue;
                                                /* compute intersection */
                if (!( source[sn].sflags & SDISTANT ?
                                sourcehit(&sr) :
                                (*ofun[source[sn].so->otype].funp)
                                (source[sn].so, &sr) )) {
                        sprintf(errmsg,
                                "aiming failure for light source \"%s\"",
                                        source[sn].so->oname);
                        error(WARNING, errmsg);
                        continue;
                }
                                                /* compute contribution */
                raycont(&sr);
                multcolor(srccnt[sn].val, sr.rcol);
                cntord[sn].brt = bright(srccnt[sn].val);
        }
                                                /* sort contributions */
        qsort(cntord, nsources, sizeof(CNTPTR), cntcmp);
        {                                       /* find last */
                register int  l, m;

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


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

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

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


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

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

                                                /* otherwise treat as source */
        } else {
                                                /* check for behind */
                if (r->rod < 0.0)
                        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);
                                                /* assign distance */
                r->rt = r->rot;
        }
}
Revision:	1.27
Committed:	Mon Dec 17 14:38:12 1990 UTC (33 years, 4 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.26:	+16 -18 lines
Log Message:	minor cleanup in srcray()
#	User	Rev	Content
1	greg	1.25	/* Copyright (c) 1990 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 "source.h"
18
19			#include "otypes.h"
20
21			#include "cone.h"
22
23			#include "face.h"
24
25			#include "random.h"
26
27
28			extern double dstrsrc; /* source distribution amount */
29	greg	1.4	extern double shadthresh; /* relative shadow threshold */
30	greg	1.12	extern double shadcert; /* shadow testing certainty */
31	greg	1.1
32	greg	1.4	SRCREC source = NULL; / our list of sources */
33	greg	1.1	int nsources = 0; /* the number of sources */
34
35	greg	1.25	static CONTRIB srccnt; / source contributions in direct() */
36			static CNTPTR cntord; / source ordering in direct() */
37	greg	1.1
38	greg	1.25
39	greg	1.1	marksources() /* find and mark source objects */
40			{
41			register OBJREC o, m;
42			register int i;
43
44			for (i = 0; i < nobjects; i++) {
45
46			o = objptr(i);
47
48			if (o->omod == OVOID)
49			continue;
50
51			m = objptr(o->omod);
52
53	greg	1.24	if (!islight(m->otype))
54	greg	1.1	continue;
55
56	greg	1.6	if (m->oargs.nfargs != (m->otype == MAT_GLOW ? 4 :
57			m->otype == MAT_SPOT ? 7 : 3))
58	greg	1.1	objerror(m, USER, "bad # arguments");
59
60	greg	1.6	if (m->otype == MAT_GLOW &&
61			o->otype != OBJ_SOURCE &&
62			m->oargs.farg[3] <= FTINY)
63	greg	1.1	continue; /* don't bother */
64
65	greg	1.4	if (source == NULL)
66			source = (SRCREC *)malloc(sizeof(SRCREC));
67			else
68			source = (SRCREC )realloc((char )source,
69			(unsigned)(nsources+1)*sizeof(SRCREC));
70			if (source == NULL)
71	greg	1.25	goto memerr;
72	greg	1.1
73	greg	1.4	newsource(&source[nsources], o);
74	greg	1.1
75	greg	1.6	if (m->otype == MAT_GLOW) {
76			source[nsources].sflags \|= SPROX;
77			source[nsources].sl.prox = m->oargs.farg[3];
78			if (o->otype == OBJ_SOURCE)
79			source[nsources].sflags \|= SSKIP;
80			} else if (m->otype == MAT_SPOT) {
81			source[nsources].sflags \|= SSPOT;
82			source[nsources].sl.s = makespot(m);
83			}
84	greg	1.1	nsources++;
85			}
86	greg	1.25	if (nsources <= 0) {
87			error(WARNING, "no light sources found");
88			return;
89			}
90			srccnt = (CONTRIB )malloc(nsourcessizeof(CONTRIB));
91			cntord = (CNTPTR )malloc(nsourcessizeof(CNTPTR));
92			if (srccnt != NULL && cntord != NULL)
93			return;
94			/* fall through */
95			memerr:
96			error(SYSTEM, "out of memory in marksources");
97	greg	1.1	}
98
99
100			newsource(src, so) /* add a source to the array */
101	greg	1.4	register SRCREC *src;
102	greg	1.1	register OBJREC *so;
103			{
104			double cos(), tan(), sqrt();
105			double theta;
106			FACE *f;
107			CONE *co;
108			int j;
109			register int i;
110
111			src->sflags = 0;
112	greg	1.6	src->nhits = 1; src->ntests = 2; /* start probability = 1/2 */
113	greg	1.1	src->so = so;
114
115			switch (so->otype) {
116			case OBJ_SOURCE:
117			if (so->oargs.nfargs != 4)
118			objerror(so, USER, "bad arguments");
119			src->sflags \|= SDISTANT;
120			VCOPY(src->sloc, so->oargs.farg);
121			if (normalize(src->sloc) == 0.0)
122			objerror(so, USER, "zero direction");
123			theta = PI/180.0/2.0 * so->oargs.farg[3];
124			if (theta <= FTINY)
125			objerror(so, USER, "zero size");
126			src->ss = theta >= PI/4 ? 1.0 : tan(theta);
127			src->ss2 = 2.0PI (1.0 - cos(theta));
128			break;
129			case OBJ_SPHERE:
130			VCOPY(src->sloc, so->oargs.farg);
131			src->ss = so->oargs.farg[3];
132			src->ss2 = PI * src->ss * src->ss;
133			break;
134			case OBJ_FACE:
135			/* get the face */
136			f = getface(so);
137			/* find the center */
138			for (j = 0; j < 3; j++) {
139			src->sloc[j] = 0.0;
140			for (i = 0; i < f->nv; i++)
141			src->sloc[j] += VERTEX(f,i)[j];
142			src->sloc[j] /= f->nv;
143			}
144			if (!inface(src->sloc, f))
145			objerror(so, USER, "cannot hit center");
146			src->ss = sqrt(f->area / PI);
147			src->ss2 = f->area;
148			break;
149			case OBJ_RING:
150			/* get the ring */
151			co = getcone(so, 0);
152			VCOPY(src->sloc, CO_P0(co));
153			if (CO_R0(co) > 0.0)
154			objerror(so, USER, "cannot hit center");
155			src->ss = CO_R1(co);
156			src->ss2 = PI * src->ss * src->ss;
157			break;
158			default:
159			objerror(so, USER, "illegal material");
160			}
161			}
162
163
164	greg	1.6	SPOT *
165			makespot(m) /* make a spotlight */
166			register OBJREC *m;
167			{
168			extern double cos();
169			register SPOT *ns;
170
171			if ((ns = (SPOT *)malloc(sizeof(SPOT))) == NULL)
172			error(SYSTEM, "out of memory in makespot");
173			ns->siz = 2.0PI (1.0 - cos(PI/180.0/2.0 * m->oargs.farg[3]));
174			VCOPY(ns->aim, m->oargs.farg+4);
175			if ((ns->flen = normalize(ns->aim)) == 0.0)
176			objerror(m, USER, "zero focus vector");
177			return(ns);
178			}
179
180
181	greg	1.1	double
182			srcray(sr, r, sn) /* send a ray to a source, return domega */
183			register RAY sr; / returned source ray */
184			RAY r; / ray which hit object */
185			register int sn; /* source number */
186			{
187			register double norm = NULL; / plane normal */
188			double ddot; /* (distance times) cosine */
189			FVECT vd;
190			double d;
191			register int i;
192
193	greg	1.4	if (source[sn].sflags & SSKIP)
194	greg	1.1	return(0.0); /* skip this source */
195
196			rayorigin(sr, r, SHADOW, 1.0); /* ignore limits */
197
198			sr->rsrc = sn; /* remember source */
199			/* get source direction */
200	greg	1.4	if (source[sn].sflags & SDISTANT)
201	greg	1.1	/* constant direction */
202	greg	1.4	VCOPY(sr->rdir, source[sn].sloc);
203	greg	1.1	else { /* compute direction */
204			for (i = 0; i < 3; i++)
205	greg	1.4	sr->rdir[i] = source[sn].sloc[i] - sr->rorg[i];
206	greg	1.1
207	greg	1.4	if (source[sn].so->otype == OBJ_FACE)
208			norm = getface(source[sn].so)->norm;
209			else if (source[sn].so->otype == OBJ_RING)
210			norm = getcone(source[sn].so,0)->ad;
211	greg	1.1
212	greg	1.2	if (norm != NULL && (ddot = -DOT(sr->rdir, norm)) <= FTINY)
213	greg	1.1	return(0.0); /* behind surface! */
214			}
215			if (dstrsrc > FTINY) {
216			/* distribute source direction */
217			for (i = 0; i < 3; i++)
218	greg	1.4	vd[i] = dstrsrc * source[sn].ss * (1.0 - 2.0*frandom());
219	greg	1.1
220			if (norm != NULL) { /* project offset */
221			d = DOT(vd, norm);
222			for (i = 0; i < 3; i++)
223			vd[i] -= d * norm[i];
224			}
225			for (i = 0; i < 3; i++) /* offset source direction */
226			sr->rdir[i] += vd[i];
227
228	greg	1.4	} else if (source[sn].sflags & SDISTANT)
229	greg	1.1	/* already normalized */
230	greg	1.4	return(source[sn].ss2);
231	greg	1.1
232			if ((d = normalize(sr->rdir)) == 0.0)
233			/* at source! */
234			return(0.0);
235
236	greg	1.4	if (source[sn].sflags & SDISTANT)
237	greg	1.1	/* domega constant */
238	greg	1.4	return(source[sn].ss2);
239	greg	1.1
240	greg	1.6	/* check proximity */
241	greg	1.27	if (source[sn].sflags & SPROX &&
242			d > source[sn].sl.prox)
243			return(0.0);
244			/* compute dot product */
245			if (norm != NULL)
246			ddot /= d;
247			else
248			ddot = 1.0;
249	greg	1.6	/* check angle */
250	greg	1.27	if (source[sn].sflags & SSPOT) {
251			if (source[sn].sl.s->siz < 2.0PI
252	greg	1.6	(1.0 + DOT(source[sn].sl.s->aim,sr->rdir)))
253	greg	1.27	return(0.0);
254			d += source[sn].sl.s->flen; /* adjust length */
255	greg	1.1	}
256	greg	1.27	/* compute domega */
257			return(ddotsource[sn].ss2/(dd));
258	greg	1.1	}
259
260
261			sourcehit(r) /* check to see if ray hit distant source */
262			register RAY *r;
263			{
264			int first, last;
265			register int i;
266
267			if (r->rsrc >= 0) { /* check only one if aimed */
268			first = last = r->rsrc;
269			} else { /* otherwise check all */
270			first = 0; last = nsources-1;
271			}
272			for (i = first; i <= last; i++)
273	greg	1.4	if (source[i].sflags & SDISTANT)
274	greg	1.1	/*
275			* Check to see if ray is within
276			* solid angle of source.
277			*/
278	greg	1.4	if (2.0PI (1.0 - DOT(source[i].sloc,r->rdir))
279			<= source[i].ss2) {
280			r->ro = source[i].so;
281			if (!(source[i].sflags & SSKIP))
282	greg	1.1	break;
283			}
284
285			if (r->ro != NULL) {
286			for (i = 0; i < 3; i++)
287			r->ron[i] = -r->rdir[i];
288			r->rod = 1.0;
289	greg	1.26	r->rox = NULL;
290	greg	1.1	return(1);
291			}
292			return(0);
293			}
294
295
296	greg	1.4	static int
297			cntcmp(sc1, sc2) /* contribution compare (descending) */
298	greg	1.9	register CNTPTR sc1, sc2;
299	greg	1.4	{
300			if (sc1->brt > sc2->brt)
301			return(-1);
302			if (sc1->brt < sc2->brt)
303			return(1);
304			return(0);
305			}
306
307
308			direct(r, f, p) /* add direct component */
309			RAY r; / ray that hit surface */
310			int (f)(); / direct component coefficient function */
311			char p; / data for f */
312			{
313	greg	1.12	extern double pow();
314	greg	1.4	register int sn;
315	greg	1.12	int nshadcheck, ncnts;
316	greg	1.10	double prob, ourthresh, hwt, test2, hit2;
317	greg	1.4	RAY sr;
318	greg	1.25	/* NOTE: srccnt and cntord global so no recursion */
319	greg	1.22	if (nsources <= 0)
320	greg	1.25	return; /* no sources?! */
321	greg	1.12	/* compute number to check */
322			nshadcheck = pow((double)nsources, shadcert) + .5;
323	greg	1.8	/* modify threshold */
324			ourthresh = shadthresh / r->rweight;
325	greg	1.4	/* potential contributions */
326			for (sn = 0; sn < nsources; sn++) {
327	greg	1.9	cntord[sn].sno = sn;
328			cntord[sn].brt = 0.0;
329	greg	1.4	/* get source ray */
330			if ((srccnt[sn].dom = srcray(&sr, r, sn)) == 0.0)
331			continue;
332			VCOPY(srccnt[sn].dir, sr.rdir);
333			/* compute coefficient */
334			(*f)(srccnt[sn].val, p, srccnt[sn].dir, srccnt[sn].dom);
335	greg	1.9	cntord[sn].brt = bright(srccnt[sn].val);
336	greg	1.15	if (cntord[sn].brt <= 0.0)
337	greg	1.4	continue;
338			/* compute intersection */
339			if (!( source[sn].sflags & SDISTANT ?
340			sourcehit(&sr) :
341			(*ofun[source[sn].so->otype].funp)
342	greg	1.25	(source[sn].so, &sr) )) {
343			sprintf(errmsg,
344			"aiming failure for light source \"%s\"",
345			source[sn].so->oname);
346			error(WARNING, errmsg);
347	greg	1.4	continue;
348	greg	1.25	}
349	greg	1.4	/* compute contribution */
350	greg	1.19	raycont(&sr);
351	greg	1.4	multcolor(srccnt[sn].val, sr.rcol);
352	greg	1.9	cntord[sn].brt = bright(srccnt[sn].val);
353	greg	1.4	}
354			/* sort contributions */
355	greg	1.9	qsort(cntord, nsources, sizeof(CNTPTR), cntcmp);
356	greg	1.13	{ /* find last */
357			register int l, m;
358
359			sn = 0; ncnts = l = nsources;
360			while ((m = (sn + ncnts) >> 1) != l) {
361			if (cntord[m].brt > 0.0)
362			sn = m;
363			else
364			ncnts = m;
365			l = m;
366			}
367			}
368	greg	1.12	/* accumulate tail */
369			for (sn = ncnts-1; sn > 0; sn--)
370			cntord[sn-1].brt += cntord[sn].brt;
371			/* start with prob=.5 */
372			hit2 = 0.5; test2 = 1.0;
373	greg	1.10	/* test for shadows */
374	greg	1.12	for (sn = 0; sn < ncnts; sn++) {
375	greg	1.10	/* check threshold */
376	greg	1.12	if ((sn+nshadcheck>=ncnts ? cntord[sn].brt :
377	greg	1.27	cntord[sn].brt-cntord[sn+nshadcheck].brt)
378			< ourthresh*bright(r->rcol))
379	greg	1.4	break;
380			/* get statistics */
381	greg	1.9	hwt = (double)source[cntord[sn].sno].nhits /
382			(double)source[cntord[sn].sno].ntests;
383	greg	1.4	test2 += hwt;
384	greg	1.9	source[cntord[sn].sno].ntests++;
385	greg	1.4	/* test for hit */
386			rayorigin(&sr, r, SHADOW, 1.0);
387	greg	1.9	VCOPY(sr.rdir, srccnt[cntord[sn].sno].dir);
388	greg	1.19	sr.rsrc = cntord[sn].sno;
389	greg	1.4	if (localhit(&sr, &thescene) &&
390	greg	1.9	sr.ro != source[cntord[sn].sno].so) {
391	greg	1.4	/* check for transmission */
392	greg	1.19	raycont(&sr);
393	greg	1.5	if (bright(sr.rcol) <= FTINY)
394	greg	1.4	continue; /* missed! */
395	greg	1.9	(*f)(srccnt[cntord[sn].sno].val, p,
396			srccnt[cntord[sn].sno].dir,
397			srccnt[cntord[sn].sno].dom);
398			multcolor(srccnt[cntord[sn].sno].val, sr.rcol);
399	greg	1.4	}
400			/* add contribution if hit */
401	greg	1.9	addcolor(r->rcol, srccnt[cntord[sn].sno].val);
402	greg	1.4	hit2 += hwt;
403	greg	1.9	source[cntord[sn].sno].nhits++;
404	greg	1.4	}
405	greg	1.7	/* weighted hit rate */
406			hwt = hit2 / test2;
407	greg	1.20	#ifdef DEBUG
408	greg	1.12	sprintf(errmsg, "%d tested, %d untested, %f hit rate\n",
409			sn, ncnts-sn, hwt);
410			eputs(errmsg);
411	greg	1.4	#endif
412			/* add in untested sources */
413	greg	1.12	for ( ; sn < ncnts; sn++) {
414	greg	1.9	prob = hwt * (double)source[cntord[sn].sno].nhits /
415			(double)source[cntord[sn].sno].ntests;
416			scalecolor(srccnt[cntord[sn].sno].val, prob);
417			addcolor(r->rcol, srccnt[cntord[sn].sno].val);
418	greg	1.4	}
419			}
420
421
422	greg	1.1	#define wrongsource(m, r) (m->otype!=MAT_ILLUM && \
423			r->rsrc>=0 && \
424	greg	1.4	source[r->rsrc].so!=r->ro)
425	greg	1.1
426			#define badambient(m, r) ((r->crtype&(AMBIENT\|SHADOW))==AMBIENT && \
427	greg	1.6	!(r->rtype&REFLECTED) && /* hack! */\
428			!(m->otype==MAT_GLOW&&r->rot>m->oargs.farg[3]))
429	greg	1.1
430			#define passillum(m, r) (m->otype==MAT_ILLUM && \
431	greg	1.4	!(r->rsrc>=0&&source[r->rsrc].so==r->ro))
432	greg	1.1
433
434			m_light(m, r) /* ray hit a light source */
435			register OBJREC *m;
436			register RAY *r;
437			{
438			/* check for over-counting */
439			if (wrongsource(m, r) \|\| badambient(m, r))
440			return;
441			/* check for passed illum */
442			if (passillum(m, r)) {
443
444			if (m->oargs.nsargs < 1 \|\| !strcmp(m->oargs.sarg[0], VOIDID))
445			raytrans(r);
446			else
447			rayshade(r, modifier(m->oargs.sarg[0]));
448
449			/* otherwise treat as source */
450			} else {
451	greg	1.16	/* check for behind */
452			if (r->rod < 0.0)
453			return;
454	greg	1.1	/* get distribution pattern */
455			raytexture(r, m->omod);
456			/* get source color */
457			setcolor(r->rcol, m->oargs.farg[0],
458			m->oargs.farg[1],
459			m->oargs.farg[2]);
460			/* modify value */
461			multcolor(r->rcol, r->pcol);
462	greg	1.21	/* assign distance */
463			r->rt = r->rot;
464	greg	1.1	}
465			}