src/rt/source.c

/* Copyright (c) 1991 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  i;
        register OBJREC  *o, *m;
        register int  ns;
                                        /* initialize dispatch table */
        initstypes();
                                        /* find direct sources */
        for (i = 0; i < nobjects; i++) {
        
                o = objptr(i);

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

                m = objptr(o->omod);

                if (!islight(m->otype))
                        continue;
        
                if (m->oargs.nfargs != (m->otype == MAT_GLOW ? 4 :
                                m->otype == MAT_SPOT ? 7 : 3))
                        objerror(m, USER, "bad # arguments");

                if (m->otype == MAT_GLOW &&
                                o->otype != OBJ_SOURCE &&
                                m->oargs.farg[3] <= FTINY)
                        continue;                       /* don't bother */

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

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

                setsource(&source[ns], o);

                if (m->otype == MAT_GLOW) {
                        source[ns].sflags |= SPROX;
                        source[ns].sl.prox = m->oargs.farg[3];
                        if (o->otype == OBJ_SOURCE)
                                source[ns].sflags |= SSKIP;
                } else if (m->otype == MAT_SPOT) {
                        source[ns].sflags |= SSPOT;
                        if ((source[ns].sl.s = makespot(m)) == NULL)
                                goto memerr;
                        if (source[ns].sflags & SFLAT &&
                                !checkspot(source[ns].sl.s,source[ns].snorm)) {
                                objerror(o, WARNING,
                                        "invalid spotlight direction");
                                source[ns].sflags |= SSKIP;
                        }
                }
        }
        if (nsources <= 0) {
                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 */
    FVECT  vd;
    register SRCREC  *srcp;
    register int  i;

    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) {     /* check location */
                        for (i = 0; i < 3; i++)
                            vd[i] = srcp->sl.s->aim[i] - sr->rorg[i];
                        d = DOT(sr->rdir,vd);
                        if (d <= FTINY)
                                continue;
                        d = DOT(vd,vd) - d*d;
                        if (PI*d > srcp->sl.s->siz)
                                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 (srcp->sl.s->siz < 2.0*PI *
                                (1.0 + DOT(srcp->sl.s->aim,sr->rdir)))
                        continue;
                                        /* adjust solid angle */
                si->dom *= d*d;
                d += srcp->sl.s->flen;
                si->dom /= d*d;
        }
        return(1);                      /* sample OK */
    }
    return(0);                  /* no more samples */
}


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

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


static int
cntcmp(sc1, sc2)                        /* contribution compare (descending) */
register CNTPTR  *sc1, *sc2;
{
        if (sc1->brt > sc2->brt)
                return(-1);
        if (sc1->brt < sc2->brt)
                return(1);
        return(0);
}


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

                ncnts = l = sn;
                sn = 0;
                while ((m = (sn + ncnts) >> 1) != l) {
                        if (cntord[m].brt > 0.0)
                                sn = m;
                        else
                                ncnts = m;
                        l = m;
                }
        }
        if (ncnts == 0)
                return;         /* no contributions! */
                                                /* accumulate tail */
        for (sn = ncnts-1; sn > 0; sn--)
                cntord[sn-1].brt += cntord[sn].brt;
                                                /* compute number to check */
        nshadcheck = pow((double)ncnts, shadcert) + .5;
                                                /* modify threshold */
        ourthresh = shadthresh / r->rweight;
                                                /* test for shadows */
        nhits = 0;
        for (sn = 0; sn < ncnts; sn++) {
                                                /* check threshold */
                if ((sn+nshadcheck>=ncnts ? cntord[sn].brt :
                                cntord[sn].brt-cntord[sn+nshadcheck].brt)
                                < ourthresh*bright(r->rcol))
                        break;
                                                /* test for hit */
                rayorigin(&sr, r, SHADOW, 1.0);
                VCOPY(sr.rdir, srccnt[cntord[sn].sndx].dir);
                sr.rsrc = srccnt[cntord[sn].sndx].sno;
                source[sr.rsrc].ntests++;       /* keep statistics */
                if (localhit(&sr, &thescene) &&
                                ( sr.ro != source[sr.rsrc].so ||
                                source[sr.rsrc].sflags & SFOLLOW )) {
                                                /* follow entire path */
                        raycont(&sr);
                        if (trace != NULL)
                                (*trace)(&sr);  /* trace execution */
                        if (bright(sr.rcol) <= FTINY)
                                continue;       /* missed! */
                        copycolor(srccnt[cntord[sn].sndx].val, sr.rcol);
                        multcolor(srccnt[cntord[sn].sndx].val,
                                        srccnt[cntord[sn].sndx].coef);
                }
                                                /* add contribution if hit */
                addcolor(r->rcol, srccnt[cntord[sn].sndx].val);
                nhits++;
                source[sr.rsrc].nhits++;
        }
                                        /* surface hit rate */
        if (sn > 0)
                hwt = (double)nhits / (double)sn;
        else
                hwt = 0.5;
#ifdef DEBUG
        sprintf(errmsg, "%d tested, %d untested, %f hit rate\n",
                        sn, ncnts-sn, hwt);
        eputs(errmsg);
#endif
                                        /* add in untested sources */
        for ( ; sn < ncnts; sn++) {
                sr.rsrc = srccnt[cntord[sn].sndx].sno;
                prob = hwt * (double)source[sr.rsrc].nhits /
                                (double)source[sr.rsrc].ntests;
                scalecolor(srccnt[cntord[sn].sndx].val, prob);
                addcolor(r->rcol, srccnt[cntord[sn].sndx].val);
        }
}
Revision:	2.2
Committed:	Thu Jan 9 09:53:00 1992 UTC (33 years, 10 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.1:	+2 -0 lines
Log Message:	added preemptive measure to avoid pow(0,0) call in direct()
#	User	Rev	Content
1	greg	1.42	/* Copyright (c) 1991 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	1.33	int i;
45	greg	1.1	register OBJREC o, m;
46	greg	1.36	register int ns;
47	greg	1.35	/* initialize dispatch table */
48			initstypes();
49			/* find direct sources */
50	greg	1.1	for (i = 0; i < nobjects; i++) {
51
52			o = objptr(i);
53
54	greg	1.35	if (!issurface(o->otype) \|\| o->omod == OVOID)
55	greg	1.1	continue;
56
57			m = objptr(o->omod);
58
59	greg	1.24	if (!islight(m->otype))
60	greg	1.1	continue;
61
62	greg	1.6	if (m->oargs.nfargs != (m->otype == MAT_GLOW ? 4 :
63			m->otype == MAT_SPOT ? 7 : 3))
64	greg	1.1	objerror(m, USER, "bad # arguments");
65
66	greg	1.6	if (m->otype == MAT_GLOW &&
67			o->otype != OBJ_SOURCE &&
68			m->oargs.farg[3] <= FTINY)
69	greg	1.1	continue; /* don't bother */
70
71	greg	1.35	if (sfun[o->otype].of == NULL \|\|
72			sfun[o->otype].of->setsrc == NULL)
73			objerror(o, USER, "illegal material");
74
75	greg	1.36	if ((ns = newsource()) < 0)
76	greg	1.25	goto memerr;
77	greg	1.1
78	greg	1.37	setsource(&source[ns], o);
79	greg	1.1
80	greg	1.6	if (m->otype == MAT_GLOW) {
81	greg	1.36	source[ns].sflags \|= SPROX;
82			source[ns].sl.prox = m->oargs.farg[3];
83	greg	1.6	if (o->otype == OBJ_SOURCE)
84	greg	1.36	source[ns].sflags \|= SSKIP;
85	greg	1.6	} else if (m->otype == MAT_SPOT) {
86	greg	1.36	source[ns].sflags \|= SSPOT;
87			if ((source[ns].sl.s = makespot(m)) == NULL)
88	greg	1.33	goto memerr;
89	greg	1.38	if (source[ns].sflags & SFLAT &&
90			!checkspot(source[ns].sl.s,source[ns].snorm)) {
91			objerror(o, WARNING,
92			"invalid spotlight direction");
93			source[ns].sflags \|= SSKIP;
94			}
95	greg	1.6	}
96	greg	1.1	}
97	greg	1.25	if (nsources <= 0) {
98			error(WARNING, "no light sources found");
99			return;
100			}
101	greg	1.33	markvirtuals(); /* find and add virtual sources */
102	greg	1.45	/* allocate our contribution arrays */
103	greg	1.48	maxcntr = nsources + MAXSPART; /* start with this many */
104	greg	1.45	srccnt = (CONTRIB )malloc(maxcntrsizeof(CONTRIB));
105			cntord = (CNTPTR )malloc(maxcntrsizeof(CNTPTR));
106	greg	1.48	if (srccnt == NULL \| cntord == NULL)
107	greg	1.33	goto memerr;
108			return;
109	greg	1.25	memerr:
110			error(SYSTEM, "out of memory in marksources");
111	greg	1.1	}
112
113
114	greg	1.45	srcray(sr, r, si) /* send a ray to a source, return domega */
115	greg	1.1	register RAY sr; / returned source ray */
116			RAY r; / ray which hit object */
117	greg	1.45	SRCINDEX si; / source sample index */
118	greg	1.1	{
119	greg	1.45	double d; /* distance to source */
120			FVECT vd;
121			register SRCREC *srcp;
122			register int i;
123	greg	1.1
124	greg	1.45	rayorigin(sr, r, SHADOW, 1.0); /* ignore limits */
125	greg	1.1
126	greg	1.47	while ((d = nextssamp(sr, si)) != 0.0) {
127	greg	1.45	sr->rsrc = si->sn; /* remember source */
128			srcp = source + si->sn;
129			if (srcp->sflags & SDISTANT) {
130			if (srcp->sflags & SSPOT) { /* check location */
131	greg	1.1	for (i = 0; i < 3; i++)
132	greg	1.45	vd[i] = srcp->sl.s->aim[i] - sr->rorg[i];
133	greg	1.40	d = DOT(sr->rdir,vd);
134	greg	1.41	if (d <= FTINY)
135	greg	1.45	continue;
136	greg	1.40	d = DOT(vd,vd) - d*d;
137	greg	1.45	if (PI*d > srcp->sl.s->siz)
138			continue;
139	greg	1.40	}
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			if (srcp->sl.s->siz < 2.0PI
149			(1.0 + DOT(srcp->sl.s->aim,sr->rdir)))
150			continue;
151			/* adjust solid angle */
152			si->dom = dd;
153			d += srcp->sl.s->flen;
154			si->dom /= d*d;
155	greg	1.1	}
156	greg	1.45	return(1); /* sample OK */
157			}
158			return(0); /* no more samples */
159	greg	1.1	}
160
161
162	greg	1.35	srcvalue(r) /* punch ray to source and compute value */
163			RAY *r;
164	greg	1.1	{
165	greg	1.35	register SRCREC *sp;
166	greg	1.1
167	greg	1.35	sp = &source[r->rsrc];
168			if (sp->sflags & SVIRTUAL) { /* virtual source */
169			/* check intersection */
170			if (!(*ofun[sp->so->otype].funp)(sp->so, r))
171			return;
172			raycont(r); /* compute contribution */
173			return;
174	greg	1.1	}
175	greg	1.35	/* compute intersection */
176			if (sp->sflags & SDISTANT ? sourcehit(r) :
177			(*ofun[sp->so->otype].funp)(sp->so, r)) {
178			if (sp->sa.success >= 0)
179			sp->sa.success++;
180			raycont(r); /* compute contribution */
181			return;
182	greg	1.1	}
183	greg	1.35	if (sp->sa.success < 0)
184			return; /* bitched already */
185			sp->sa.success -= AIMREQT;
186			if (sp->sa.success >= 0)
187			return; /* leniency */
188			sprintf(errmsg, "aiming failure for light source \"%s\"",
189			sp->so->oname);
190			error(WARNING, errmsg); /* issue warning */
191	greg	1.1	}
192
193
194	greg	1.4	static int
195			cntcmp(sc1, sc2) /* contribution compare (descending) */
196	greg	1.9	register CNTPTR sc1, sc2;
197	greg	1.4	{
198			if (sc1->brt > sc2->brt)
199			return(-1);
200			if (sc1->brt < sc2->brt)
201			return(1);
202			return(0);
203			}
204
205
206			direct(r, f, p) /* add direct component */
207			RAY r; / ray that hit surface */
208			int (f)(); / direct component coefficient function */
209			char p; / data for f */
210			{
211	greg	1.42	extern int (*trace)();
212	greg	1.12	extern double pow();
213	greg	1.4	register int sn;
214	greg	1.45	SRCINDEX si;
215	greg	1.12	int nshadcheck, ncnts;
216	greg	1.29	int nhits;
217	greg	1.45	double prob, ourthresh, hwt;
218	greg	1.4	RAY sr;
219	greg	1.25	/* NOTE: srccnt and cntord global so no recursion */
220	greg	1.22	if (nsources <= 0)
221	greg	1.25	return; /* no sources?! */
222	greg	1.4	/* potential contributions */
223	greg	1.45	initsrcindex(&si);
224			for (sn = 0; srcray(&sr, r, &si); sn++) {
225			if (sn >= maxcntr) {
226			maxcntr = sn + MAXSPART;
227			srccnt = (CONTRIB )realloc((char )srccnt,
228			maxcntr*sizeof(CONTRIB));
229			cntord = (CNTPTR )realloc((char )cntord,
230			maxcntr*sizeof(CNTPTR));
231	greg	1.48	if (srccnt == NULL \| cntord == NULL)
232	greg	1.45	error(SYSTEM, "out of memory in direct");
233			}
234			cntord[sn].sndx = sn;
235	greg	1.46	srccnt[sn].sno = sr.rsrc;
236	greg	1.4	/* compute coefficient */
237	greg	1.46	(*f)(srccnt[sn].coef, p, sr.rdir, si.dom);
238	greg	1.34	cntord[sn].brt = bright(srccnt[sn].coef);
239	greg	1.15	if (cntord[sn].brt <= 0.0)
240	greg	1.4	continue;
241	greg	1.45	VCOPY(srccnt[sn].dir, sr.rdir);
242	greg	1.35	/* compute potential */
243			sr.revf = srcvalue;
244			rayvalue(&sr);
245	greg	1.34	copycolor(srccnt[sn].val, sr.rcol);
246			multcolor(srccnt[sn].val, srccnt[sn].coef);
247	greg	1.9	cntord[sn].brt = bright(srccnt[sn].val);
248	greg	1.4	}
249			/* sort contributions */
250	greg	1.45	qsort(cntord, sn, sizeof(CNTPTR), cntcmp);
251	greg	1.13	{ /* find last */
252			register int l, m;
253
254	greg	1.45	ncnts = l = sn;
255			sn = 0;
256	greg	1.13	while ((m = (sn + ncnts) >> 1) != l) {
257			if (cntord[m].brt > 0.0)
258			sn = m;
259			else
260			ncnts = m;
261			l = m;
262			}
263			}
264	greg	2.2	if (ncnts == 0)
265			return; /* no contributions! */
266	greg	1.12	/* accumulate tail */
267			for (sn = ncnts-1; sn > 0; sn--)
268			cntord[sn-1].brt += cntord[sn].brt;
269	greg	1.45	/* compute number to check */
270			nshadcheck = pow((double)ncnts, shadcert) + .5;
271			/* modify threshold */
272			ourthresh = shadthresh / r->rweight;
273	greg	1.10	/* test for shadows */
274	greg	1.29	nhits = 0;
275	greg	1.12	for (sn = 0; sn < ncnts; sn++) {
276	greg	1.10	/* check threshold */
277	greg	1.12	if ((sn+nshadcheck>=ncnts ? cntord[sn].brt :
278	greg	1.27	cntord[sn].brt-cntord[sn+nshadcheck].brt)
279			< ourthresh*bright(r->rcol))
280	greg	1.4	break;
281			/* test for hit */
282			rayorigin(&sr, r, SHADOW, 1.0);
283	greg	1.45	VCOPY(sr.rdir, srccnt[cntord[sn].sndx].dir);
284			sr.rsrc = srccnt[cntord[sn].sndx].sno;
285			source[sr.rsrc].ntests++; /* keep statistics */
286	greg	1.4	if (localhit(&sr, &thescene) &&
287	greg	1.45	( sr.ro != source[sr.rsrc].so \|\|
288			source[sr.rsrc].sflags & SFOLLOW )) {
289	greg	1.33	/* follow entire path */
290	greg	1.19	raycont(&sr);
291	greg	1.42	if (trace != NULL)
292			(trace)(&sr); / trace execution */
293	greg	1.5	if (bright(sr.rcol) <= FTINY)
294	greg	1.4	continue; /* missed! */
295	greg	1.45	copycolor(srccnt[cntord[sn].sndx].val, sr.rcol);
296			multcolor(srccnt[cntord[sn].sndx].val,
297			srccnt[cntord[sn].sndx].coef);
298	greg	1.4	}
299			/* add contribution if hit */
300	greg	1.45	addcolor(r->rcol, srccnt[cntord[sn].sndx].val);
301	greg	1.29	nhits++;
302	greg	1.45	source[sr.rsrc].nhits++;
303	greg	1.4	}
304	greg	1.29	/* surface hit rate */
305			if (sn > 0)
306			hwt = (double)nhits / (double)sn;
307			else
308			hwt = 0.5;
309	greg	1.20	#ifdef DEBUG
310	greg	1.12	sprintf(errmsg, "%d tested, %d untested, %f hit rate\n",
311			sn, ncnts-sn, hwt);
312			eputs(errmsg);
313	greg	1.4	#endif
314			/* add in untested sources */
315	greg	1.12	for ( ; sn < ncnts; sn++) {
316	greg	1.45	sr.rsrc = srccnt[cntord[sn].sndx].sno;
317			prob = hwt * (double)source[sr.rsrc].nhits /
318			(double)source[sr.rsrc].ntests;
319			scalecolor(srccnt[cntord[sn].sndx].val, prob);
320			addcolor(r->rcol, srccnt[cntord[sn].sndx].val);
321	greg	1.1	}
322			}