src/rt/virtuals.c

/* Copyright (c) 1991 Regents of the University of California */

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

/*
 * Routines for simulating virtual light sources
 *      Thus far, we only support planar mirrors.
 */

#include  "ray.h"

#include  "octree.h"

#include  "otypes.h"

#include  "source.h"

#include  "random.h"


double  getdisk();

static OBJECT  *vobject;                /* virtual source objects */
static int  nvobjects = 0;              /* number of virtual source objects */


markvirtuals()                  /* find and mark virtual sources */
{
        register OBJREC  *o;
        register int  i;
                                        /* check number of direct relays */
        if (directrelay <= 0)
                return;
                                        /* find virtual source objects */
        for (i = 0; i < nobjects; i++) {
                o = objptr(i);
                if (!issurface(o->otype) || o->omod == OVOID)
                        continue;
                if (!isvlight(objptr(o->omod)->otype))
                        continue;
                if (sfun[o->otype].of == NULL ||
                                sfun[o->otype].of->getpleq == NULL)
                        objerror(o, USER, "illegal material");
                if (nvobjects == 0)
                        vobject = (OBJECT *)malloc(sizeof(OBJECT));
                else
                        vobject = (OBJECT *)realloc((char *)vobject,
                                (unsigned)(nvobjects+1)*sizeof(OBJECT));
                if (vobject == NULL)
                        error(SYSTEM, "out of memory in addvirtuals");
                vobject[nvobjects++] = i;
        }
        if (nvobjects == 0)
                return;
#ifdef DEBUG
        fprintf(stderr, "found %d virtual source objects\n", nvobjects);
#endif
                                        /* append virtual sources */
        for (i = nsources; i-- > 0; )
                addvirtuals(i, directrelay);
                                        /* done with our object list */
        free((char *)vobject);
        nvobjects = 0;
}


addvirtuals(sn, nr)             /* add virtuals associated with source */
int  sn;
int  nr;
{
        register int  i;
                                /* check relay limit first */
        if (nr <= 0)
                return;
        if (source[sn].sflags & SSKIP)
                return;
                                /* check each virtual object for projection */
        for (i = 0; i < nvobjects; i++)
                                        /* vproject() calls us recursively */
                vproject(objptr(vobject[i]), sn, nr-1);
}


vproject(o, sn, n)              /* create projected source(s) if they exist */
OBJREC  *o;
int  sn;
int  n;
{
        register int  i;
        register VSMATERIAL  *vsmat;
        MAT4  proj;
        int  ns;

        if (o == source[sn].so) /* objects cannot project themselves */
                return;
                                /* get virtual source material */
        vsmat = sfun[objptr(o->omod)->otype].mf;
                                /* project virtual sources */
        for (i = 0; i < vsmat->nproj; i++)
                if ((*vsmat->vproj)(proj, o, &source[sn], i))
                        if ((ns = makevsrc(o, sn, proj)) >= 0) {
#ifdef DEBUG
                                virtverb(ns, stderr);
#endif
                                addvirtuals(ns, n);
                        }
}


int
makevsrc(op, sn, pm)            /* make virtual source if reasonable */
OBJREC  *op;
register int  sn;
MAT4  pm;
{
        FVECT  nsloc, nsnorm, ocent, v;
        double  maxrad2, d;
        int  nsflags;
        SPOT  theirspot, ourspot;
        register int  i;

        nsflags = source[sn].sflags | (SVIRTUAL|SSPOT|SFOLLOW);
                                        /* get object center and max. radius */
        maxrad2 = getdisk(ocent, op, sn);
        if (maxrad2 <= FTINY)                   /* too small? */
                return(-1);
                                        /* get location and spot */
        if (source[sn].sflags & SDISTANT) {             /* distant source */
                if (source[sn].sflags & SPROX)
                        return(-1);             /* should never get here! */
                multv3(nsloc, source[sn].sloc, pm);
                VCOPY(ourspot.aim, ocent);
                ourspot.siz = PI*maxrad2;
                ourspot.flen = 0.;
                if (source[sn].sflags & SSPOT) {
                        copystruct(&theirspot, source[sn].sl.s);
                        multp3(theirspot.aim, source[sn].sl.s->aim, pm);
                        d = ourspot.siz;
                        if (!commonbeam(&ourspot, &theirspot, nsloc))
                                return(-1);     /* no overlap */
                        if (ourspot.siz < d-FTINY) {    /* it shrunk */
                                d = beamdisk(v, op, &ourspot, nsloc);
                                if (d <= FTINY)
                                        return(-1);
                                if (d < maxrad2) {
                                        maxrad2 = d;
                                        VCOPY(ocent, v);
                                }
                        }
                }
        } else {                                /* local source */
                multp3(nsloc, source[sn].sloc, pm);
                for (i = 0; i < 3; i++)
                        ourspot.aim[i] = ocent[i] - nsloc[i];
                if ((d = normalize(ourspot.aim)) == 0.)
                        return(-1);             /* at source!! */
                if (source[sn].sflags & SPROX && d > source[sn].sl.prox)
                        return(-1);             /* too far away */
                ourspot.siz = 2.*PI*(1. - d/sqrt(d*d+maxrad2));
                ourspot.flen = 0.;
                if (source[sn].sflags & SSPOT) {
                        copystruct(&theirspot, source[sn].sl.s);
                        multv3(theirspot.aim, source[sn].sl.s->aim, pm);
                        d = ourspot.siz;
                        if (!commonspot(&ourspot, &theirspot, nsloc))
                                return(-1);     /* no overlap */
                        if (ourspot.siz < d-FTINY) {    /* it shrunk */
                                d = spotdisk(v, op, &ourspot, nsloc);
                                if (d <= FTINY)
                                        return(-1);
                                if (d < maxrad2) {
                                        maxrad2 = d;
                                        VCOPY(ocent, v);
                                }
                        }
                        ourspot.flen = theirspot.flen;
                }
                if (source[sn].sflags & SFLAT) {        /* behind source? */
                        multv3(nsnorm, source[sn].snorm, pm);
                        if (checkspot(&ourspot, nsnorm) < 0)
                                return(-1);
                }
        }
                                        /* pretest visibility */
        nsflags = vstestvis(nsflags, op, ocent, maxrad2, sn);
        if (nsflags & SSKIP)
                return(-1);     /* obstructed */
                                        /* it all checks out, so make it */
        if ((i = newsource()) < 0)
                goto memerr;
        source[i].sflags = nsflags;
        VCOPY(source[i].sloc, nsloc);
        if (nsflags & SFLAT)
                VCOPY(source[i].snorm, nsnorm);
        source[i].ss = source[sn].ss; source[i].ss2 = source[sn].ss2;
        if ((source[i].sl.s = (SPOT *)malloc(sizeof(SPOT))) == NULL)
                goto memerr;
        copystruct(source[i].sl.s, &ourspot);
        if (nsflags & SPROX)
                source[i].sl.prox = source[sn].sl.prox;
        source[i].sa.svnext = sn;
        source[i].so = op;
        return(i);
memerr:
        error(SYSTEM, "out of memory in makevsrc");
}


double
getdisk(oc, op, sn)             /* get visible object disk */
FVECT  oc;
OBJREC  *op;
register int  sn;
{
        double  rad2, roffs, offs, d, rd, rdoto;
        FVECT  rnrm, nrm;
                                /* first, use object getdisk function */
        rad2 = getmaxdisk(oc, op);
        if (!(source[sn].sflags & SVIRTUAL))
                return(rad2);           /* all done for normal source */
                                /* check for correct side of relay surface */
        roffs = getplaneq(rnrm, source[sn].so);
        rd = DOT(rnrm, source[sn].sloc);        /* source projection */
        if (!(source[sn].sflags & SDISTANT))
                rd -= roffs;
        d = DOT(rnrm, oc) - roffs;      /* disk distance to relay plane */
        if ((d > 0.) ^ (rd > 0.))
                return(rad2);           /* OK if opposite sides */
        if (d*d >= rad2)
                return(0.);             /* no relay is possible */
                                /* we need a closer look */
        offs = getplaneq(nrm, op);
        rdoto = DOT(rnrm, nrm);
        if (d*d >= rad2*(1.-rdoto*rdoto))
                return(0.);             /* disk entirely on projection side */
                                /* should shrink disk but I'm lazy */
        return(rad2);
}


int
vstestvis(f, o, oc, or2, sn)            /* pretest source visibility */
int  f;                 /* virtual source flags */
OBJREC  *o;             /* relay object */
FVECT  oc;              /* relay object center */
double  or2;            /* relay object radius squared */
register int  sn;       /* target source number */
{
        RAY  sr;
        FVECT  onorm;
        FVECT  offsdir;
        double  or, d;
        int  infront;
        int  ssn;
        int  nhit, nok;
        register int  i, n;
                                /* return if pretesting disabled */
        if (vspretest <= 0)
                return(f);
                                /* get surface normal */
        getplaneq(onorm, o);
                                /* set number of rays to sample */
        if (source[sn].sflags & SDISTANT) {
                n = (2./3.*PI*PI)*or2/(thescene.cusize*thescene.cusize)*
                                vspretest + .5;
                infront = DOT(onorm, source[sn].sloc) > 0.;
        } else {
                for (i = 0; i < 3; i++)
                        offsdir[i] = source[sn].sloc[i] - oc[i];
                n = or2/DOT(offsdir,offsdir)*vspretest + .5;
                infront = DOT(onorm, offsdir) > 0.;
        }
        if (n < 1) n = 1;
#ifdef DEBUG
        fprintf(stderr, "pretesting source %d in object %s with %d rays\n",
                        sn, o->oname, n);
#endif
                                /* sample */
        or = sqrt(or2);
        ssn = 25*n;
        nhit = nok = 0;
        while (n-- > 0) {
                                        /* get sample point */
                do {
                        if (--ssn < 0) {
#ifdef DEBUG
                                fprintf(stderr, "\ttoo hard to hit\n");
#endif
                                return(f);      /* too small a target! */
                        }
                        for (i = 0; i < 3; i++)
                                offsdir[i] = or*(1. -
                                                2.*urand(931*i+5827+ssn));
                        for (i = 0; i < 3; i++)
                                sr.rorg[i] = oc[i] + offsdir[i];
                        d = DOT(offsdir,onorm);
                        if (infront)
                                for (i = 0; i < 3; i++) {
                                        sr.rorg[i] -= (d-.0001)*onorm[i];
                                        sr.rdir[i] = -onorm[i];
                                }
                        else
                                for (i = 0; i < 3; i++) {
                                        sr.rorg[i] -= (d+.0001)*onorm[i];
                                        sr.rdir[i] = onorm[i];
                                }
                        rayorigin(&sr, NULL, PRIMARY, 1.0);
                } while (!(*ofun[o->otype].funp)(o, &sr));
                                        /* check against source */
                samplendx++;
                if (srcray(&sr, NULL, sn) == 0.)
                        continue;
                sr.revf = srcvalue;
                rayvalue(&sr);
                if (bright(sr.rcol) <= FTINY)
                        continue;
                nok++;
                                        /* check against obstructions */
                srcray(&sr, NULL, sn);
                rayvalue(&sr);
                if (bright(sr.rcol) > FTINY)
                        nhit++;
                if (nhit > 0 && nhit < nok) {
#ifdef DEBUG
                        fprintf(stderr, "\tpartially occluded\n");
#endif
                        return(f);              /* need to shadow test */
                }
        }
        if (nhit == 0) {
#ifdef DEBUG
                fprintf(stderr, "\t0%% hit rate\n");
#endif
                return(f | SSKIP);      /* 0% hit rate:  totally occluded */
        }
#ifdef DEBUG
        fprintf(stderr, "\t100%% hit rate\n");
#endif
        return(f & ~SFOLLOW);           /* 100% hit rate:  no occlusion */
}
        

#ifdef DEBUG
virtverb(sn, fp)        /* print verbose description of virtual source */
register int  sn;
FILE  *fp;
{
        register int  i;

        fprintf(fp, "%s virtual source %d in %s %s\n",
                        source[sn].sflags & SDISTANT ? "distant" : "local",
                        sn, ofun[source[sn].so->otype].funame,
                        source[sn].so->oname);
        fprintf(fp, "\tat (%f,%f,%f)\n",
                source[sn].sloc[0], source[sn].sloc[1], source[sn].sloc[2]);
        fprintf(fp, "\tlinked to source %d (%s)\n",
                source[sn].sa.svnext, source[source[sn].sa.svnext].so->oname);
        if (source[sn].sflags & SFOLLOW)
                fprintf(fp, "\talways followed\n");
        else
                fprintf(fp, "\tnever followed\n");
        if (!(source[sn].sflags & SSPOT))
                return;
        fprintf(fp, "\twith spot aim (%f,%f,%f) and size %f\n",
                        source[sn].sl.s->aim[0], source[sn].sl.s->aim[1],
                        source[sn].sl.s->aim[2], source[sn].sl.s->siz);
}
#endif
Revision:	1.11
Committed:	Tue Jun 25 15:48:11 1991 UTC (32 years, 10 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.10:	+9 -9 lines
Log Message:	another minor bug in vstestvis()
#	User	Rev	Content
1	greg	1.1	/* Copyright (c) 1991 Regents of the University of California */
2
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* Routines for simulating virtual light sources
9			* Thus far, we only support planar mirrors.
10			*/
11
12			#include "ray.h"
13
14	greg	1.7	#include "octree.h"
15
16	greg	1.3	#include "otypes.h"
17
18	greg	1.1	#include "source.h"
19
20	greg	1.7	#include "random.h"
21	greg	1.1
22
23	greg	1.7	double getdisk();
24
25	greg	1.1	static OBJECT vobject; / virtual source objects */
26			static int nvobjects = 0; /* number of virtual source objects */
27
28
29			markvirtuals() /* find and mark virtual sources */
30			{
31			register OBJREC *o;
32			register int i;
33			/* check number of direct relays */
34			if (directrelay <= 0)
35			return;
36			/* find virtual source objects */
37			for (i = 0; i < nobjects; i++) {
38			o = objptr(i);
39	greg	1.3	if (!issurface(o->otype) \|\| o->omod == OVOID)
40	greg	1.1	continue;
41			if (!isvlight(objptr(o->omod)->otype))
42			continue;
43	greg	1.3	if (sfun[o->otype].of == NULL \|\|
44			sfun[o->otype].of->getpleq == NULL)
45			objerror(o, USER, "illegal material");
46	greg	1.1	if (nvobjects == 0)
47			vobject = (OBJECT *)malloc(sizeof(OBJECT));
48			else
49			vobject = (OBJECT )realloc((char )vobject,
50			(unsigned)(nvobjects+1)*sizeof(OBJECT));
51			if (vobject == NULL)
52			error(SYSTEM, "out of memory in addvirtuals");
53			vobject[nvobjects++] = i;
54			}
55			if (nvobjects == 0)
56			return;
57	greg	1.4	#ifdef DEBUG
58			fprintf(stderr, "found %d virtual source objects\n", nvobjects);
59			#endif
60	greg	1.1	/* append virtual sources */
61			for (i = nsources; i-- > 0; )
62	greg	1.7	addvirtuals(i, directrelay);
63	greg	1.1	/* done with our object list */
64			free((char *)vobject);
65			nvobjects = 0;
66			}
67
68
69	greg	1.4	addvirtuals(sn, nr) /* add virtuals associated with source */
70			int sn;
71	greg	1.1	int nr;
72			{
73			register int i;
74			/* check relay limit first */
75			if (nr <= 0)
76			return;
77	greg	1.7	if (source[sn].sflags & SSKIP)
78			return;
79	greg	1.1	/* check each virtual object for projection */
80			for (i = 0; i < nvobjects; i++)
81	greg	1.3	/* vproject() calls us recursively */
82	greg	1.4	vproject(objptr(vobject[i]), sn, nr-1);
83	greg	1.1	}
84
85
86	greg	1.4	vproject(o, sn, n) /* create projected source(s) if they exist */
87	greg	1.3	OBJREC *o;
88	greg	1.4	int sn;
89	greg	1.3	int n;
90			{
91			register int i;
92			register VSMATERIAL *vsmat;
93			MAT4 proj;
94	greg	1.4	int ns;
95
96			if (o == source[sn].so) /* objects cannot project themselves */
97			return;
98	greg	1.3	/* get virtual source material */
99			vsmat = sfun[objptr(o->omod)->otype].mf;
100			/* project virtual sources */
101			for (i = 0; i < vsmat->nproj; i++)
102	greg	1.4	if ((*vsmat->vproj)(proj, o, &source[sn], i))
103			if ((ns = makevsrc(o, sn, proj)) >= 0) {
104			#ifdef DEBUG
105	greg	1.6	virtverb(ns, stderr);
106	greg	1.4	#endif
107	greg	1.3	addvirtuals(ns, n);
108	greg	1.4	}
109	greg	1.3	}
110
111
112	greg	1.4	int
113			makevsrc(op, sn, pm) /* make virtual source if reasonable */
114	greg	1.1	OBJREC *op;
115	greg	1.4	register int sn;
116	greg	1.1	MAT4 pm;
117			{
118	greg	1.9	FVECT nsloc, nsnorm, ocent, v;
119			double maxrad2, d;
120	greg	1.3	int nsflags;
121	greg	1.1	SPOT theirspot, ourspot;
122			register int i;
123	greg	1.3
124	greg	1.6	nsflags = source[sn].sflags \| (SVIRTUAL\|SSPOT\|SFOLLOW);
125	greg	1.1	/* get object center and max. radius */
126	greg	1.6	maxrad2 = getdisk(ocent, op, sn);
127			if (maxrad2 <= FTINY) /* too small? */
128			return(-1);
129	greg	1.1	/* get location and spot */
130	greg	1.4	if (source[sn].sflags & SDISTANT) { /* distant source */
131			if (source[sn].sflags & SPROX)
132	greg	1.5	return(-1); /* should never get here! */
133	greg	1.4	multv3(nsloc, source[sn].sloc, pm);
134	greg	1.6	VCOPY(ourspot.aim, ocent);
135			ourspot.siz = PI*maxrad2;
136			ourspot.flen = 0.;
137	greg	1.4	if (source[sn].sflags & SSPOT) {
138			copystruct(&theirspot, source[sn].sl.s);
139			multp3(theirspot.aim, source[sn].sl.s->aim, pm);
140	greg	1.9	d = ourspot.siz;
141	greg	1.6	if (!commonbeam(&ourspot, &theirspot, nsloc))
142	greg	1.9	return(-1); /* no overlap */
143			if (ourspot.siz < d-FTINY) { /* it shrunk */
144			d = beamdisk(v, op, &ourspot, nsloc);
145			if (d <= FTINY)
146			return(-1);
147			if (d < maxrad2) {
148			maxrad2 = d;
149			VCOPY(ocent, v);
150			}
151			}
152	greg	1.1	}
153			} else { /* local source */
154	greg	1.4	multp3(nsloc, source[sn].sloc, pm);
155	greg	1.6	for (i = 0; i < 3; i++)
156			ourspot.aim[i] = ocent[i] - nsloc[i];
157	greg	1.9	if ((d = normalize(ourspot.aim)) == 0.)
158	greg	1.6	return(-1); /* at source!! */
159	greg	1.9	if (source[sn].sflags & SPROX && d > source[sn].sl.prox)
160	greg	1.6	return(-1); /* too far away */
161	greg	1.9	ourspot.siz = 2.PI(1. - d/sqrt(d*d+maxrad2));
162	greg	1.6	ourspot.flen = 0.;
163	greg	1.4	if (source[sn].sflags & SSPOT) {
164			copystruct(&theirspot, source[sn].sl.s);
165			multv3(theirspot.aim, source[sn].sl.s->aim, pm);
166	greg	1.9	d = ourspot.siz;
167	greg	1.6	if (!commonspot(&ourspot, &theirspot, nsloc))
168			return(-1); /* no overlap */
169	greg	1.9	if (ourspot.siz < d-FTINY) { /* it shrunk */
170			d = spotdisk(v, op, &ourspot, nsloc);
171			if (d <= FTINY)
172			return(-1);
173			if (d < maxrad2) {
174			maxrad2 = d;
175			VCOPY(ocent, v);
176			}
177			}
178	greg	1.6	ourspot.flen = theirspot.flen;
179	greg	1.1	}
180	greg	1.4	if (source[sn].sflags & SFLAT) { /* behind source? */
181			multv3(nsnorm, source[sn].snorm, pm);
182	greg	1.6	if (checkspot(&ourspot, nsnorm) < 0)
183	greg	1.5	return(-1);
184	greg	1.1	}
185			}
186	greg	1.7	/* pretest visibility */
187			nsflags = vstestvis(nsflags, op, ocent, maxrad2, sn);
188			if (nsflags & SSKIP)
189			return(-1); /* obstructed */
190			/* it all checks out, so make it */
191	greg	1.6	if ((i = newsource()) < 0)
192	greg	1.1	goto memerr;
193	greg	1.6	source[i].sflags = nsflags;
194			VCOPY(source[i].sloc, nsloc);
195	greg	1.3	if (nsflags & SFLAT)
196	greg	1.6	VCOPY(source[i].snorm, nsnorm);
197			source[i].ss = source[sn].ss; source[i].ss2 = source[sn].ss2;
198			if ((source[i].sl.s = (SPOT *)malloc(sizeof(SPOT))) == NULL)
199			goto memerr;
200			copystruct(source[i].sl.s, &ourspot);
201	greg	1.3	if (nsflags & SPROX)
202	greg	1.6	source[i].sl.prox = source[sn].sl.prox;
203			source[i].sa.svnext = sn;
204			source[i].so = op;
205			return(i);
206	greg	1.1	memerr:
207			error(SYSTEM, "out of memory in makevsrc");
208			}
209
210
211	greg	1.6	double
212			getdisk(oc, op, sn) /* get visible object disk */
213			FVECT oc;
214			OBJREC *op;
215			register int sn;
216			{
217			double rad2, roffs, offs, d, rd, rdoto;
218			FVECT rnrm, nrm;
219			/* first, use object getdisk function */
220	greg	1.9	rad2 = getmaxdisk(oc, op);
221	greg	1.6	if (!(source[sn].sflags & SVIRTUAL))
222			return(rad2); /* all done for normal source */
223			/* check for correct side of relay surface */
224	greg	1.9	roffs = getplaneq(rnrm, source[sn].so);
225	greg	1.6	rd = DOT(rnrm, source[sn].sloc); /* source projection */
226			if (!(source[sn].sflags & SDISTANT))
227			rd -= roffs;
228			d = DOT(rnrm, oc) - roffs; /* disk distance to relay plane */
229			if ((d > 0.) ^ (rd > 0.))
230			return(rad2); /* OK if opposite sides */
231			if (d*d >= rad2)
232	greg	1.9	return(0.); /* no relay is possible */
233	greg	1.6	/* we need a closer look */
234	greg	1.9	offs = getplaneq(nrm, op);
235	greg	1.6	rdoto = DOT(rnrm, nrm);
236			if (dd >= rad2(1.-rdoto*rdoto))
237			return(0.); /* disk entirely on projection side */
238			/* should shrink disk but I'm lazy */
239			return(rad2);
240			}
241
242
243	greg	1.7	int
244			vstestvis(f, o, oc, or2, sn) /* pretest source visibility */
245			int f; /* virtual source flags */
246			OBJREC o; / relay object */
247			FVECT oc; /* relay object center */
248			double or2; /* relay object radius squared */
249			register int sn; /* target source number */
250	greg	1.1	{
251	greg	1.7	RAY sr;
252			FVECT onorm;
253			FVECT offsdir;
254			double or, d;
255	greg	1.8	int infront;
256			int ssn;
257	greg	1.11	int nhit, nok;
258	greg	1.7	register int i, n;
259			/* return if pretesting disabled */
260			if (vspretest <= 0)
261			return(f);
262			/* get surface normal */
263	greg	1.9	getplaneq(onorm, o);
264	greg	1.7	/* set number of rays to sample */
265	greg	1.8	if (source[sn].sflags & SDISTANT) {
266	greg	1.7	n = (2./3.PIPI)or2/(thescene.cusizethescene.cusize)*
267			vspretest + .5;
268	greg	1.8	infront = DOT(onorm, source[sn].sloc) > 0.;
269			} else {
270			for (i = 0; i < 3; i++)
271			offsdir[i] = source[sn].sloc[i] - oc[i];
272	greg	1.9	n = or2/DOT(offsdir,offsdir)*vspretest + .5;
273	greg	1.8	infront = DOT(onorm, offsdir) > 0.;
274			}
275	greg	1.7	if (n < 1) n = 1;
276	greg	1.9	#ifdef DEBUG
277			fprintf(stderr, "pretesting source %d in object %s with %d rays\n",
278			sn, o->oname, n);
279			#endif
280	greg	1.7	/* sample */
281	greg	1.8	or = sqrt(or2);
282	greg	1.9	ssn = 25*n;
283	greg	1.11	nhit = nok = 0;
284	greg	1.7	while (n-- > 0) {
285	greg	1.8	/* get sample point */
286			do {
287	greg	1.9	if (--ssn < 0) {
288			#ifdef DEBUG
289			fprintf(stderr, "\ttoo hard to hit\n");
290			#endif
291	greg	1.8	return(f); /* too small a target! */
292	greg	1.9	}
293	greg	1.8	for (i = 0; i < 3; i++)
294			offsdir[i] = or*(1. -
295			2.urand(931i+5827+ssn));
296			for (i = 0; i < 3; i++)
297			sr.rorg[i] = oc[i] + offsdir[i];
298			d = DOT(offsdir,onorm);
299			if (infront)
300			for (i = 0; i < 3; i++) {
301			sr.rorg[i] -= (d-.0001)*onorm[i];
302			sr.rdir[i] = -onorm[i];
303			}
304			else
305			for (i = 0; i < 3; i++) {
306			sr.rorg[i] -= (d+.0001)*onorm[i];
307			sr.rdir[i] = onorm[i];
308			}
309			rayorigin(&sr, NULL, PRIMARY, 1.0);
310			} while (!(*ofun[o->otype].funp)(o, &sr));
311			/* check against source */
312	greg	1.7	samplendx++;
313	greg	1.9	if (srcray(&sr, NULL, sn) == 0.)
314	greg	1.7	continue;
315			sr.revf = srcvalue;
316			rayvalue(&sr);
317			if (bright(sr.rcol) <= FTINY)
318			continue;
319	greg	1.11	nok++;
320	greg	1.7	/* check against obstructions */
321			srcray(&sr, NULL, sn);
322			rayvalue(&sr);
323	greg	1.11	if (bright(sr.rcol) > FTINY)
324			nhit++;
325			if (nhit > 0 && nhit < nok) {
326	greg	1.9	#ifdef DEBUG
327	greg	1.11	fprintf(stderr, "\tpartially occluded\n");
328	greg	1.9	#endif
329	greg	1.11	return(f); /* need to shadow test */
330			}
331	greg	1.1	}
332	greg	1.9	if (nhit == 0) {
333			#ifdef DEBUG
334			fprintf(stderr, "\t0%% hit rate\n");
335			#endif
336	greg	1.7	return(f \| SSKIP); /* 0% hit rate: totally occluded */
337	greg	1.9	}
338			#ifdef DEBUG
339			fprintf(stderr, "\t100%% hit rate\n");
340			#endif
341			return(f & ~SFOLLOW); /* 100% hit rate: no occlusion */
342	greg	1.1	}
343	greg	1.7
344	greg	1.4
345			#ifdef DEBUG
346	greg	1.6	virtverb(sn, fp) /* print verbose description of virtual source */
347			register int sn;
348	greg	1.4	FILE *fp;
349			{
350			register int i;
351
352			fprintf(fp, "%s virtual source %d in %s %s\n",
353	greg	1.6	source[sn].sflags & SDISTANT ? "distant" : "local",
354			sn, ofun[source[sn].so->otype].funame,
355			source[sn].so->oname);
356	greg	1.4	fprintf(fp, "\tat (%f,%f,%f)\n",
357	greg	1.6	source[sn].sloc[0], source[sn].sloc[1], source[sn].sloc[2]);
358	greg	1.4	fprintf(fp, "\tlinked to source %d (%s)\n",
359	greg	1.6	source[sn].sa.svnext, source[source[sn].sa.svnext].so->oname);
360			if (source[sn].sflags & SFOLLOW)
361	greg	1.4	fprintf(fp, "\talways followed\n");
362			else
363			fprintf(fp, "\tnever followed\n");
364	greg	1.6	if (!(source[sn].sflags & SSPOT))
365	greg	1.4	return;
366			fprintf(fp, "\twith spot aim (%f,%f,%f) and size %f\n",
367	greg	1.6	source[sn].sl.s->aim[0], source[sn].sl.s->aim[1],
368			source[sn].sl.s->aim[2], source[sn].sl.s->siz);
369	greg	1.4	}
370			#endif