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;
        double  maxrad2;
        int  nsflags;
        double  d1;
        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);
                        if (!commonbeam(&ourspot, &theirspot, nsloc))
                                return(-1);             /* no overlap */
                }
        } else {                                /* local source */
                multp3(nsloc, source[sn].sloc, pm);
                for (i = 0; i < 3; i++)
                        ourspot.aim[i] = ocent[i] - nsloc[i];
                if ((d1 = normalize(ourspot.aim)) == 0.)
                        return(-1);             /* at source!! */
                if (source[sn].sflags & SPROX && d1 > source[sn].sl.prox)
                        return(-1);             /* too far away */
                ourspot.siz = 2.*PI*(1. - d1/sqrt(d1*d1+maxrad2));
                ourspot.flen = 0.;
                if (source[sn].sflags & SSPOT) {
                        copystruct(&theirspot, source[sn].sl.s);
                        multv3(theirspot.aim, source[sn].sl.s->aim, pm);
                        if (!commonspot(&ourspot, &theirspot, nsloc))
                                return(-1);     /* no overlap */
                        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 = (*sfun[op->otype].of->getdisk)(oc, op);
        if (!(source[sn].sflags & SVIRTUAL))
                return(rad2);           /* all done for normal source */
                                /* check for correct side of relay surface */
        roffs = (*sfun[source[sn].so->otype].of->getpleq)(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 = (*sfun[op->otype].of->getpleq)(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  nok, nhit;
        register int  i, n;
                                /* return if pretesting disabled */
        if (vspretest <= 0)
                return(f);
                                /* get surface normal */
        (*sfun[o->otype].of->getpleq)(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 {
                n = or2/dist2(oc,source[sn].sloc)*vspretest + .5;
                for (i = 0; i < 3; i++)
                        offsdir[i] = source[sn].sloc[i] - oc[i];
                infront = DOT(onorm, offsdir) > 0.;
        }
        if (n < 1) n = 1;
                                /* sample */
        or = sqrt(or2);
        ssn = 7*n;
        nhit = nok = 0;
        while (n-- > 0) {
                                        /* get sample point */
                do {
                        if (--ssn < 0)
                                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) == 0.0)
                        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)
                        continue;
                nhit++;
        }
                                /* interpret results */
        if (nhit == 0)
                return(f | SSKIP);      /* 0% hit rate:  totally occluded */
        if (nhit == nok)
                return(f & ~SFOLLOW);   /* 100% hit rate:  no occlusion */
        return(f);              /* no comment */
}
        

#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:	1.8
Committed:	Tue Jun 25 08:52:04 1991 UTC (34 years, 4 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.7:	+34 -15 lines
Log Message:	improved presampling
#	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	1.6	FVECT nsloc, nsnorm, ocent;
119			double maxrad2;
120	greg	1.3	int nsflags;
121			double d1;
122	greg	1.1	SPOT theirspot, ourspot;
123			register int i;
124	greg	1.3
125	greg	1.6	nsflags = source[sn].sflags \| (SVIRTUAL\|SSPOT\|SFOLLOW);
126	greg	1.1	/* get object center and max. radius */
127	greg	1.6	maxrad2 = getdisk(ocent, op, sn);
128			if (maxrad2 <= FTINY) /* too small? */
129			return(-1);
130	greg	1.1	/* get location and spot */
131	greg	1.4	if (source[sn].sflags & SDISTANT) { /* distant source */
132			if (source[sn].sflags & SPROX)
133	greg	1.5	return(-1); /* should never get here! */
134	greg	1.4	multv3(nsloc, source[sn].sloc, pm);
135	greg	1.6	VCOPY(ourspot.aim, ocent);
136			ourspot.siz = PI*maxrad2;
137			ourspot.flen = 0.;
138	greg	1.4	if (source[sn].sflags & SSPOT) {
139			copystruct(&theirspot, source[sn].sl.s);
140			multp3(theirspot.aim, source[sn].sl.s->aim, pm);
141	greg	1.6	if (!commonbeam(&ourspot, &theirspot, nsloc))
142	greg	1.5	return(-1); /* no overlap */
143	greg	1.1	}
144			} else { /* local source */
145	greg	1.4	multp3(nsloc, source[sn].sloc, pm);
146	greg	1.6	for (i = 0; i < 3; i++)
147			ourspot.aim[i] = ocent[i] - nsloc[i];
148			if ((d1 = normalize(ourspot.aim)) == 0.)
149			return(-1); /* at source!! */
150			if (source[sn].sflags & SPROX && d1 > source[sn].sl.prox)
151			return(-1); /* too far away */
152			ourspot.siz = 2.PI(1. - d1/sqrt(d1*d1+maxrad2));
153			ourspot.flen = 0.;
154	greg	1.4	if (source[sn].sflags & SSPOT) {
155			copystruct(&theirspot, source[sn].sl.s);
156			multv3(theirspot.aim, source[sn].sl.s->aim, pm);
157	greg	1.6	if (!commonspot(&ourspot, &theirspot, nsloc))
158			return(-1); /* no overlap */
159			ourspot.flen = theirspot.flen;
160	greg	1.1	}
161	greg	1.4	if (source[sn].sflags & SFLAT) { /* behind source? */
162			multv3(nsnorm, source[sn].snorm, pm);
163	greg	1.6	if (checkspot(&ourspot, nsnorm) < 0)
164	greg	1.5	return(-1);
165	greg	1.1	}
166			}
167	greg	1.7	/* pretest visibility */
168			nsflags = vstestvis(nsflags, op, ocent, maxrad2, sn);
169			if (nsflags & SSKIP)
170			return(-1); /* obstructed */
171			/* it all checks out, so make it */
172	greg	1.6	if ((i = newsource()) < 0)
173	greg	1.1	goto memerr;
174	greg	1.6	source[i].sflags = nsflags;
175			VCOPY(source[i].sloc, nsloc);
176	greg	1.3	if (nsflags & SFLAT)
177	greg	1.6	VCOPY(source[i].snorm, nsnorm);
178			source[i].ss = source[sn].ss; source[i].ss2 = source[sn].ss2;
179			if ((source[i].sl.s = (SPOT *)malloc(sizeof(SPOT))) == NULL)
180			goto memerr;
181			copystruct(source[i].sl.s, &ourspot);
182	greg	1.3	if (nsflags & SPROX)
183	greg	1.6	source[i].sl.prox = source[sn].sl.prox;
184			source[i].sa.svnext = sn;
185			source[i].so = op;
186			return(i);
187	greg	1.1	memerr:
188			error(SYSTEM, "out of memory in makevsrc");
189			}
190
191
192	greg	1.6	double
193			getdisk(oc, op, sn) /* get visible object disk */
194			FVECT oc;
195			OBJREC *op;
196			register int sn;
197			{
198			double rad2, roffs, offs, d, rd, rdoto;
199			FVECT rnrm, nrm;
200			/* first, use object getdisk function */
201			rad2 = (*sfun[op->otype].of->getdisk)(oc, op);
202			if (!(source[sn].sflags & SVIRTUAL))
203			return(rad2); /* all done for normal source */
204			/* check for correct side of relay surface */
205			roffs = (*sfun[source[sn].so->otype].of->getpleq)(rnrm, source[sn].so);
206			rd = DOT(rnrm, source[sn].sloc); /* source projection */
207			if (!(source[sn].sflags & SDISTANT))
208			rd -= roffs;
209			d = DOT(rnrm, oc) - roffs; /* disk distance to relay plane */
210			if ((d > 0.) ^ (rd > 0.))
211			return(rad2); /* OK if opposite sides */
212			if (d*d >= rad2)
213			return(.0); /* no relay is possible */
214			/* we need a closer look */
215			offs = (*sfun[op->otype].of->getpleq)(nrm, op);
216			rdoto = DOT(rnrm, nrm);
217			if (dd >= rad2(1.-rdoto*rdoto))
218			return(0.); /* disk entirely on projection side */
219			/* should shrink disk but I'm lazy */
220			return(rad2);
221			}
222
223
224	greg	1.7	int
225			vstestvis(f, o, oc, or2, sn) /* pretest source visibility */
226			int f; /* virtual source flags */
227			OBJREC o; / relay object */
228			FVECT oc; /* relay object center */
229			double or2; /* relay object radius squared */
230			register int sn; /* target source number */
231	greg	1.1	{
232	greg	1.7	RAY sr;
233			FVECT onorm;
234			FVECT offsdir;
235			double or, d;
236	greg	1.8	int infront;
237			int ssn;
238	greg	1.7	int nok, nhit;
239			register int i, n;
240			/* return if pretesting disabled */
241			if (vspretest <= 0)
242			return(f);
243			/* get surface normal */
244			(*sfun[o->otype].of->getpleq)(onorm, o);
245			/* set number of rays to sample */
246	greg	1.8	if (source[sn].sflags & SDISTANT) {
247	greg	1.7	n = (2./3.PIPI)or2/(thescene.cusizethescene.cusize)*
248			vspretest + .5;
249	greg	1.8	infront = DOT(onorm, source[sn].sloc) > 0.;
250			} else {
251	greg	1.7	n = or2/dist2(oc,source[sn].sloc)*vspretest + .5;
252	greg	1.8	for (i = 0; i < 3; i++)
253			offsdir[i] = source[sn].sloc[i] - oc[i];
254			infront = DOT(onorm, offsdir) > 0.;
255			}
256	greg	1.7	if (n < 1) n = 1;
257			/* sample */
258	greg	1.8	or = sqrt(or2);
259			ssn = 7*n;
260	greg	1.7	nhit = nok = 0;
261			while (n-- > 0) {
262	greg	1.8	/* get sample point */
263			do {
264			if (--ssn < 0)
265			return(f); /* too small a target! */
266			for (i = 0; i < 3; i++)
267			offsdir[i] = or*(1. -
268			2.urand(931i+5827+ssn));
269			for (i = 0; i < 3; i++)
270			sr.rorg[i] = oc[i] + offsdir[i];
271			d = DOT(offsdir,onorm);
272			if (infront)
273			for (i = 0; i < 3; i++) {
274			sr.rorg[i] -= (d-.0001)*onorm[i];
275			sr.rdir[i] = -onorm[i];
276			}
277			else
278			for (i = 0; i < 3; i++) {
279			sr.rorg[i] -= (d+.0001)*onorm[i];
280			sr.rdir[i] = onorm[i];
281			}
282			rayorigin(&sr, NULL, PRIMARY, 1.0);
283			} while (!(*ofun[o->otype].funp)(o, &sr));
284			/* check against source */
285	greg	1.7	samplendx++;
286			if (srcray(&sr, NULL, sn) == 0.0)
287			continue;
288			sr.revf = srcvalue;
289			rayvalue(&sr);
290			if (bright(sr.rcol) <= FTINY)
291			continue;
292			nok++;
293			/* check against obstructions */
294			srcray(&sr, NULL, sn);
295			rayvalue(&sr);
296			if (bright(sr.rcol) <= FTINY)
297			continue;
298			nhit++;
299	greg	1.1	}
300	greg	1.7	/* interpret results */
301			if (nhit == 0)
302			return(f \| SSKIP); /* 0% hit rate: totally occluded */
303			if (nhit == nok)
304			return(f & ~SFOLLOW); /* 100% hit rate: no occlusion */
305			return(f); /* no comment */
306	greg	1.1	}
307	greg	1.7
308	greg	1.4
309			#ifdef DEBUG
310	greg	1.6	virtverb(sn, fp) /* print verbose description of virtual source */
311			register int sn;
312	greg	1.4	FILE *fp;
313			{
314			register int i;
315
316			fprintf(fp, "%s virtual source %d in %s %s\n",
317	greg	1.6	source[sn].sflags & SDISTANT ? "distant" : "local",
318			sn, ofun[source[sn].so->otype].funame,
319			source[sn].so->oname);
320	greg	1.4	fprintf(fp, "\tat (%f,%f,%f)\n",
321	greg	1.6	source[sn].sloc[0], source[sn].sloc[1], source[sn].sloc[2]);
322	greg	1.4	fprintf(fp, "\tlinked to source %d (%s)\n",
323	greg	1.6	source[sn].sa.svnext, source[source[sn].sa.svnext].so->oname);
324			if (source[sn].sflags & SFOLLOW)
325	greg	1.4	fprintf(fp, "\talways followed\n");
326			else
327			fprintf(fp, "\tnever followed\n");
328	greg	1.6	if (!(source[sn].sflags & SSPOT))
329	greg	1.4	return;
330			fprintf(fp, "\twith spot aim (%f,%f,%f) and size %f\n",
331	greg	1.6	source[sn].sl.s->aim[0], source[sn].sl.s->aim[1],
332			source[sn].sl.s->aim[2], source[sn].sl.s->siz);
333	greg	1.4	}
334			#endif