--- ray/src/rt/source.c	1991/08/13 12:16:37	1.43
+++ ray/src/rt/source.c	2005/04/15 04:44:51	2.49
@@ -1,63 +1,89 @@
-/* Copyright (c) 1991 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char RCSid[] = "$Id: source.c,v 2.49 2005/04/15 04:44:51 greg Exp $";
 #endif
-
 /*
  *  source.c - routines dealing with illumination sources.
  *
- *     8/20/85
+ *  External symbols declared in source.h
  */
 
 #include  "ray.h"
-
-#include  "octree.h"
-
 #include  "otypes.h"
-
+#include  "rtotypes.h"
 #include  "source.h"
-
 #include  "random.h"
 
+extern double  ssampdist;		/* scatter sampling distance */
+
+#ifndef MAXSSAMP
+#define MAXSSAMP	16		/* maximum samples per ray */
+#endif
+
 /*
  * 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  sno;		/* source number */
+	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 */
 
+static int cntcmp(const void *p1, const void *p2);
 
-marksources()			/* find and mark source objects */
+
+extern OBJREC *			/* find an object's actual material */
+findmaterial(register OBJREC *o)
 {
+	while (!ismaterial(o->otype)) {
+		if (o->otype == MOD_ALIAS && o->oargs.nsargs) {
+			OBJECT  aobj;
+			OBJREC  *ao;
+			aobj = lastmod(objndx(o), o->oargs.sarg[0]);
+			if (aobj < 0)
+				objerror(o, USER, "bad reference");
+			ao = objptr(aobj);
+			if (ismaterial(ao->otype))
+				return(ao);
+		}
+		if (o->omod == OVOID)
+			return(NULL);
+		o = objptr(o->omod);
+	}
+	return(o);		/* mixtures will return NULL */
+}
+
+
+extern void
+marksources(void)			/* find and mark source objects */
+{
+	int  foundsource = 0;
 	int  i;
 	register OBJREC  *o, *m;
 	register int  ns;
 					/* initialize dispatch table */
 	initstypes();
 					/* find direct sources */
-	for (i = 0; i < nobjects; i++) {
+	for (i = 0; i < nsceneobjs; i++) {
 	
 		o = objptr(i);
 
 		if (!issurface(o->otype) || o->omod == OVOID)
 			continue;
-
-		m = objptr(o->omod);
-
-		if (!islight(m->otype))
-			continue;
+					/* find material */
+		m = findmaterial(objptr(o->omod));
+		if (m == NULL || !islight(m->otype))
+			continue;	/* not source modifier */
 	
 		if (m->oargs.nfargs != (m->otype == MAT_GLOW ? 4 :
 				m->otype == MAT_SPOT ? 7 : 3))
@@ -67,6 +93,9 @@ marksources()			/* find and mark source objects */
 				o->otype != OBJ_SOURCE &&
 				m->oargs.farg[3] <= FTINY)
 			continue;			/* don't bother */
+		if (m->oargs.farg[0] <= FTINY && m->oargs.farg[1] <= FTINY &&
+				m->oargs.farg[2] <= FTINY)
+			continue;			/* don't bother */
 
 		if (sfun[o->otype].of == NULL ||
 				sfun[o->otype].of->setsrc == NULL)
@@ -80,7 +109,7 @@ marksources()			/* find and mark source objects */
 		if (m->otype == MAT_GLOW) {
 			source[ns].sflags |= SPROX;
 			source[ns].sl.prox = m->oargs.farg[3];
-			if (o->otype == OBJ_SOURCE)
+			if (source[ns].sflags & SDISTANT)
 				source[ns].sflags |= SSKIP;
 		} else if (m->otype == MAT_SPOT) {
 			source[ns].sflags |= SSPOT;
@@ -93,15 +122,22 @@ marksources()			/* find and mark source objects */
 				source[ns].sflags |= SSKIP;
 			}
 		}
+#if  SHADCACHE
+		initobscache(ns);
+#endif
+		if (!(source[ns].sflags & SSKIP))
+			foundsource++;
 	}
-	if (nsources <= 0) {
+	if (!foundsource) {
 		error(WARNING, "no light sources found");
 		return;
 	}
 	markvirtuals();			/* find and add virtual sources */
-	srccnt = (CONTRIB *)malloc(nsources*sizeof(CONTRIB));
-	cntord = (CNTPTR *)malloc(nsources*sizeof(CNTPTR));
-	if (srccnt == NULL || cntord == NULL)
+				/* 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:
@@ -109,94 +145,71 @@ memerr:
 }
 
 
-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 */
+extern void
+freesources(void)			/* free all source structures */
 {
-	double  ddot;			/* (distance times) cosine */
-	FVECT  vd;
-	double  d;
-	register int  i;
+	if (nsources > 0) {
+#if SHADCACHE
+		while (nsources--)
+			freeobscache(&source[nsources]);
+#endif
+		free((void *)source);
+		source = NULL;
+		nsources = 0;
+	}
+	if (maxcntr <= 0)
+		return;
+	free((void *)srccnt);
+	srccnt = NULL;
+	free((void *)cntord);
+	cntord = NULL;
+	maxcntr = 0;
+}
 
-	if (source[sn].sflags & SSKIP)
-		return(0.0);			/* skip this source */
 
-	rayorigin(sr, r, SHADOW, 1.0);		/* ignore limits */
+extern int
+srcray(				/* send a ray to a source, return domega */
+	register RAY  *sr,		/* returned source ray */
+	RAY  *r,			/* ray which hit object */
+	SRCINDEX  *si			/* source sample index */
+)
+{
+    double  d;				/* distance to source */
+    register SRCREC  *srcp;
 
-	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];
+    rayorigin(sr, r, SHADOW, 1.0);		/* ignore limits */
 
-		if (source[sn].sflags & SFLAT &&
-			(ddot = -DOT(sr->rdir, source[sn].snorm)) <= FTINY)
-			return(0.0);		/* behind surface! */
+    while ((d = nextssamp(sr, si)) != 0.0) {
+	sr->rsrc = si->sn;			/* remember source */
+	srcp = source + si->sn;
+	if (srcp->sflags & SDISTANT) {
+		if (srcp->sflags & SSPOT && spotout(sr, srcp->sl.s))
+			continue;
+		return(1);		/* sample OK */
 	}
-	if (dstrsrc > FTINY) {
-					/* distribute source direction */
-		dimlist[ndims] = sn + 8831;
-		peano(vd, 3, urand(ilhash(dimlist,ndims+1)+samplendx), .01);
-		for (i = 0; i < 3; i++)
-			vd[i] = dstrsrc * source[sn].ss * (1. - 2.*vd[i]);
-		if (source[sn].sflags & SFLAT) {	/* project offset */
-			d = DOT(vd, source[sn].snorm);
-			for (i = 0; i < 3; i++)
-				vd[i] -= d * source[sn].snorm[i];
-		}
-		for (i = 0; i < 3; i++)		/* offset source direction */
-			sr->rdir[i] += vd[i];
-						/* normalize */
-		d = normalize(sr->rdir);
-
-	} else if (!(source[sn].sflags & SDISTANT))
-						/* normalize direction */
-		d = normalize(sr->rdir);
-
-	if (source[sn].sflags & SDISTANT) {
-		if (source[sn].sflags & SSPOT) {	/* check location */
-			for (i = 0; i < 3; i++)
-				vd[i] = source[sn].sl.s->aim[i] - sr->rorg[i];
-			d = DOT(sr->rdir,vd);
-			if (d <= FTINY)
-				return(0.0);
-			d = DOT(vd,vd) - d*d;
-			if (PI*d > source[sn].sl.s->siz)
-				return(0.0);
-		}
-		return(source[sn].ss2);		/* domega constant */
-	}
-						/* check direction */
-	if (d == 0.0)
-		return(0.0);
+				/* local source */
 						/* check proximity */
-	if (source[sn].sflags & SPROX &&
-			d > source[sn].sl.prox)
-		return(0.0);
-						/* compute dot product */
-	if (source[sn].sflags & SFLAT)
-		ddot /= d;
-	else
-		ddot = 1.0;
+	if (srcp->sflags & SPROX && d > srcp->sl.prox)
+		continue;
 						/* 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 */
+	if (srcp->sflags & SSPOT) {
+		if (spotout(sr, srcp->sl.s))
+			continue;
+					/* adjust solid angle */
+		si->dom *= d*d;
+		d += srcp->sl.s->flen;
+		si->dom /= d*d;
 	}
-						/* compute domega */
-	return(ddot*source[sn].ss2/(d*d));
+	return(1);			/* sample OK */
+    }
+    return(0);			/* no more samples */
 }
 
 
-srcvalue(r)			/* punch ray to source and compute value */
-RAY  *r;
+extern void
+srcvalue(			/* punch ray to source and compute value */
+	register RAY  *r
+)
 {
 	register SRCREC  *sp;
 
@@ -205,7 +218,9 @@ RAY  *r;
 					/* check intersection */
 		if (!(*ofun[sp->so->otype].funp)(sp->so, r))
 			return;
-		raycont(r);		/* compute contribution */
+		if (!rayshade(r, r->ro->omod))	/* compute contribution */
+			goto nomat;
+		rayparticipate(r);
 		return;
 	}
 					/* compute intersection */
@@ -213,9 +228,12 @@ RAY  *r;
 			(*ofun[sp->so->otype].funp)(sp->so, r)) {
 		if (sp->sa.success >= 0)
 			sp->sa.success++;
-		raycont(r);		/* compute contribution */
+		if (!rayshade(r, r->ro->omod))	/* compute contribution */
+			goto nomat;
+		rayparticipate(r);
 		return;
 	}
+					/* we missed our mark! */
 	if (sp->sa.success < 0)
 		return;			/* bitched already */
 	sp->sa.success -= AIMREQT;
@@ -224,13 +242,104 @@ RAY  *r;
 	sprintf(errmsg, "aiming failure for light source \"%s\"",
 			sp->so->oname);
 	error(WARNING, errmsg);		/* issue warning */
+	return;
+nomat:
+	objerror(r->ro, USER, "material not found");
 }
 
 
 static int
-cntcmp(sc1, sc2)			/* contribution compare (descending) */
-register CNTPTR  *sc1, *sc2;
+transillum(			/* check if material is transparent illum */
+	OBJECT	obj
+)
 {
+	OBJREC *m = findmaterial(objptr(obj));
+	
+	if (m == NULL)
+		return(1);
+	if (m->otype != MAT_ILLUM)
+		return(0);
+	return(!m->oargs.nsargs || !strcmp(m->oargs.sarg[0], VOIDID));
+}
+
+
+extern int
+sourcehit(			/* check to see if ray hit distant source */
+	register RAY  *r
+)
+{
+	int  glowsrc = -1;
+	int  transrc = -1;
+	int  first, last;
+	register int  i;
+
+	if (r->rsrc >= 0) {		/* check only one if aimed */
+		first = last = r->rsrc;
+	} else {			/* otherwise check all */
+		first = 0; last = nsources-1;
+	}
+	for (i = first; i <= last; i++) {
+		if ((source[i].sflags & (SDISTANT|SVIRTUAL)) != SDISTANT)
+			continue;
+		/*
+		 * Check to see if ray is within
+		 * solid angle of source.
+		 */
+		if (2.*PI*(1. - DOT(source[i].sloc,r->rdir)) > source[i].ss2)
+			continue;
+					/* is it the only possibility? */
+		if (first == last) {
+			r->ro = source[i].so;
+			break;
+		}
+		/*
+		 * If it's a glow or transparent illum, just remember it.
+		 */
+		if (source[i].sflags & SSKIP) {
+			glowsrc = i;
+			continue;
+		}
+		if (transillum(source[i].so->omod)) {
+			transrc = i;
+			continue;
+		}
+		r->ro = source[i].so;	/* otherwise, use first hit */
+		break;
+	}
+	/*
+	 * Do we need fallback?
+	 */
+	if (r->ro == NULL) {
+		if (transrc >= 0 && r->crtype & (AMBIENT|SPECULAR))
+			return(0);	/* avoid overcounting */
+		if (glowsrc >= 0)
+			r->ro = source[glowsrc].so;
+		else
+			return(0);	/* nothing usable */
+	}
+	/*
+	 * Make assignments.
+	 */
+	r->robj = objndx(r->ro);
+	for (i = 0; i < 3; i++)
+		r->ron[i] = -r->rdir[i];
+	r->rod = 1.0;
+	r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
+	r->uv[0] = r->uv[1] = 0.0;
+	r->rox = NULL;
+	return(1);
+}
+
+
+static int
+cntcmp(				/* contribution compare (descending) */
+	const void *p1,
+	const void *p2
+)
+{
+	register const CNTPTR  *sc1 = (const CNTPTR *)p1;
+	register const CNTPTR  *sc2 = (const CNTPTR *)p2;
+
 	if (sc1->brt > sc2->brt)
 		return(-1);
 	if (sc1->brt < sc2->brt)
@@ -239,51 +348,64 @@ register CNTPTR  *sc1, *sc2;
 }
 
 
-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 void
+direct(					/* add direct component */
+	RAY  *r,			/* ray that hit surface */
+	srcdirf_t *f,			/* direct component coefficient function */
+	void  *p			/* data for f */
+)
 {
-	extern int  (*trace)();
-	extern double  pow();
 	register int  sn;
+	register CONTRIB  *scp;
+	SRCINDEX  si;
 	int  nshadcheck, ncnts;
 	int  nhits;
-	double  dom, prob, ourthresh, hwt;
+	double  prob, ourthresh, hwt;
 	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 ((dom = srcray(&sr, r, sn)) == 0.0)
-			continue;
-		VCOPY(srccnt[sn].dir, sr.rdir);
+	initsrcindex(&si);
+	for (sn = 0; srcray(&sr, r, &si); sn++) {
+		if (sn >= maxcntr) {
+			maxcntr = sn + MAXSPART;
+			srccnt = (CONTRIB *)realloc((void *)srccnt,
+					maxcntr*sizeof(CONTRIB));
+			cntord = (CNTPTR *)realloc((void *)cntord,
+					maxcntr*sizeof(CNTPTR));
+			if ((srccnt == NULL) | (cntord == NULL))
+				error(SYSTEM, "out of memory in direct");
+		}
+		cntord[sn].sndx = sn;
+		scp = srccnt + sn;
+		scp->sno = sr.rsrc;
 						/* compute coefficient */
-		(*f)(srccnt[sn].coef, p, srccnt[sn].dir, dom);
-		cntord[sn].brt = bright(srccnt[sn].coef);
+		(*f)(scp->coef, p, sr.rdir, si.dom);
+		cntord[sn].brt = bright(scp->coef);
 		if (cntord[sn].brt <= 0.0)
 			continue;
+#if SHADCACHE
+						/* check shadow cache */
+		if (si.np == 1 && srcblocked(&sr)) {
+			cntord[sn].brt = 0.0;
+			continue;
+		}
+#endif
+		VCOPY(scp->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);
+		srcvalue(&sr);
+		copycolor(scp->val, sr.rcol);
+		multcolor(scp->val, scp->coef);
+		cntord[sn].brt = bright(scp->val);
 	}
 						/* sort contributions */
-	qsort(cntord, nsources, sizeof(CNTPTR), cntcmp);
+	qsort(cntord, sn, sizeof(CNTPTR), cntcmp);
 	{					/* find last */
 		register int  l, m;
 
-		sn = 0; ncnts = l = nsources;
+		ncnts = l = sn;
+		sn = 0;
 		while ((m = (sn + ncnts) >> 1) != l) {
 			if (cntord[m].brt > 0.0)
 				sn = m;
@@ -292,56 +414,284 @@ char  *p;			/* data for f */
 			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++) {
+	for (nhits = 0, hwt = 0.0, sn = 0; sn < ncnts;
+			hwt += (double)source[scp->sno].nhits /
+				(double)source[scp->sno].ntests,
+			sn++) {
 						/* check threshold */
 		if ((sn+nshadcheck>=ncnts ? cntord[sn].brt :
 				cntord[sn].brt-cntord[sn+nshadcheck].brt)
 				< ourthresh*bright(r->rcol))
 			break;
-						/* get statistics */
-		source[cntord[sn].sno].ntests++;
+		scp = srccnt + cntord[sn].sndx;
 						/* test for hit */
 		rayorigin(&sr, r, SHADOW, 1.0);
-		VCOPY(sr.rdir, srccnt[cntord[sn].sno].dir);
-		sr.rsrc = cntord[sn].sno;
+		VCOPY(sr.rdir, scp->dir);
+		sr.rsrc = scp->sno;
+						/* keep statistics */
+		if (source[scp->sno].ntests++ > 0xfffffff0) {
+			source[scp->sno].ntests >>= 1;
+			source[scp->sno].nhits >>= 1;
+		}
 		if (localhit(&sr, &thescene) &&
-				( sr.ro != source[cntord[sn].sno].so ||
-				source[cntord[sn].sno].sflags & SFOLLOW )) {
+				( sr.ro != source[scp->sno].so ||
+				source[scp->sno].sflags & SFOLLOW )) {
 						/* follow entire path */
 			raycont(&sr);
+			rayparticipate(&sr);
 			if (trace != NULL)
 				(*trace)(&sr);	/* trace execution */
-			if (bright(sr.rcol) <= FTINY)
+			if (bright(sr.rcol) <= FTINY) {
+#if SHADCACHE
+				if ((scp <= srccnt || scp[-1].sno != scp->sno)
+						&& (scp >= srccnt+ncnts-1 ||
+						    scp[1].sno != scp->sno))
+					srcblocker(&sr);
+#endif
 				continue;	/* missed! */
-			copycolor(srccnt[cntord[sn].sno].val, sr.rcol);
-			multcolor(srccnt[cntord[sn].sno].val,
-					srccnt[cntord[sn].sno].coef);
+			}
+			copycolor(scp->val, sr.rcol);
+			multcolor(scp->val, scp->coef);
 		}
 						/* add contribution if hit */
-		addcolor(r->rcol, srccnt[cntord[sn].sno].val);
+		addcolor(r->rcol, scp->val);
 		nhits++;
-		source[cntord[sn].sno].nhits++;
+		source[scp->sno].nhits++;
 	}
-					/* surface hit rate */
-	if (sn > 0)
-		hwt = (double)nhits / (double)sn;
+					/* source hit rate */
+	if (hwt > FTINY)
+		hwt = (double)nhits / hwt;
 	else
 		hwt = 0.5;
 #ifdef DEBUG
-	sprintf(errmsg, "%d tested, %d untested, %f hit rate\n",
+	sprintf(errmsg, "%d tested, %d untested, %f conditional hit rate\n",
 			sn, ncnts-sn, hwt);
 	eputs(errmsg);
 #endif
 					/* add in untested sources */
 	for ( ; sn < ncnts; sn++) {
-		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);
+		scp = srccnt + cntord[sn].sndx;
+		prob = hwt * (double)source[scp->sno].nhits /
+				(double)source[scp->sno].ntests;
+		if (prob > 1.0)
+			prob = 1.0;
+		scalecolor(scp->val, prob);
+		addcolor(r->rcol, scp->val);
 	}
+}
+
+
+extern void
+srcscatter(			/* compute source scattering into ray */
+	register RAY  *r
+)
+{
+	int  oldsampndx;
+	int  nsamps;
+	RAY  sr;
+	SRCINDEX  si;
+	double  t, d;
+	double  re, ge, be;
+	COLOR  cvext;
+	int  i, j;
+
+	if (r->slights == NULL || r->slights[0] == 0
+			|| r->gecc >= 1.-FTINY || r->rot >= FHUGE)
+		return;
+	if (ssampdist <= FTINY || (nsamps = r->rot/ssampdist + .5) < 1)
+		nsamps = 1;
+#if MAXSSAMP
+	else if (nsamps > MAXSSAMP)
+		nsamps = MAXSSAMP;
+#endif
+	oldsampndx = samplendx;
+	samplendx = random()&0x7fff;		/* randomize */
+	for (i = r->slights[0]; i > 0; i--) {	/* for each source */
+		for (j = 0; j < nsamps; j++) {	/* for each sample position */
+			samplendx++;
+			t = r->rot * (j+frandom())/nsamps;
+							/* extinction */
+			re = t*colval(r->cext,RED);
+			ge = t*colval(r->cext,GRN);
+			be = t*colval(r->cext,BLU);
+			setcolor(cvext,	re > 92. ? 0. : exp(-re),
+					ge > 92. ? 0. : exp(-ge),
+					be > 92. ? 0. : exp(-be));
+			if (intens(cvext) <= FTINY)
+				break;			/* too far away */
+			sr.rorg[0] = r->rorg[0] + r->rdir[0]*t;
+			sr.rorg[1] = r->rorg[1] + r->rdir[1]*t;
+			sr.rorg[2] = r->rorg[2] + r->rdir[2]*t;
+			sr.rmax = 0.;
+			initsrcindex(&si);	/* sample ray to this source */
+			si.sn = r->slights[i];
+			nopart(&si, &sr);
+			if (!srcray(&sr, NULL, &si) ||
+					sr.rsrc != r->slights[i])
+				continue;		/* no path */
+#if SHADCACHE
+			if (srcblocked(&sr))		/* check shadow cache */
+				continue;
+#endif
+			copycolor(sr.cext, r->cext);
+			copycolor(sr.albedo, r->albedo);
+			sr.gecc = r->gecc;
+			sr.slights = r->slights;
+			rayvalue(&sr);			/* eval. source ray */
+			if (bright(sr.rcol) <= FTINY) {
+#if SHADCACHE
+				srcblocker(&sr);	/* add blocker to cache */
+#endif
+				continue;
+			}
+			if (r->gecc <= FTINY)		/* compute P(theta) */
+				d = 1.;
+			else {
+				d = DOT(r->rdir, sr.rdir);
+				d = 1. + r->gecc*r->gecc - 2.*r->gecc*d;
+				d = (1. - r->gecc*r->gecc) / (d*sqrt(d));
+			}
+							/* other factors */
+			d *= si.dom * r->rot / (4.*PI*nsamps);
+			multcolor(sr.rcol, r->cext);
+			multcolor(sr.rcol, r->albedo);
+			scalecolor(sr.rcol, d);
+			multcolor(sr.rcol, cvext);
+			addcolor(r->rcol, sr.rcol);	/* add it in */
+		}
+	}
+	samplendx = oldsampndx;
+}
+
+
+/****************************************************************
+ * The following macros were separated from the m_light() routine
+ * because they are very nasty and difficult to understand.
+ */
+
+/* illumblock *
+ *
+ * We cannot allow an illum to pass to another illum, because that
+ * would almost certainly constitute overcounting.
+ * However, we do allow an illum to pass to another illum
+ * that is actually going to relay to a virtual light source.
+ * We also prevent an illum from passing to a glow; this provides a
+ * convenient mechanism for defining detailed light source
+ * geometry behind (or inside) an effective radiator.
+ */
+
+static int
+weaksrcmat(OBJECT obj)		/* identify material */
+{
+	OBJREC *m = findmaterial(objptr(obj));
+	
+	if (m == NULL) return(0);
+	return((m->otype==MAT_ILLUM) | (m->otype==MAT_GLOW));
+}
+
+#define  illumblock(m, r)	(!(source[r->rsrc].sflags&SVIRTUAL) && \
+				r->rod > 0.0 && \
+				weaksrcmat(source[r->rsrc].so->omod))
+
+/* wrongsource *
+ *
+ * This source is the wrong source (ie. overcounted) if we are
+ * aimed to a different source than the one we hit and the one
+ * we hit is not an illum that should be passed.
+ */
+
+#define  wrongsource(m, r)	(r->rsrc>=0 && source[r->rsrc].so!=r->ro && \
+				(m->otype!=MAT_ILLUM || illumblock(m,r)))
+
+/* distglow *
+ *
+ * A distant glow is an object that sometimes acts as a light source,
+ * but is too far away from the test point to be one in this case.
+ * (Glows with negative radii should NEVER participate in illumination.)
+ */
+
+#define  distglow(m, r, d)	(m->otype==MAT_GLOW && \
+				m->oargs.farg[3] >= -FTINY && \
+				d > m->oargs.farg[3])
+
+/* badcomponent *
+ *
+ * We must avoid counting light sources in the ambient calculation,
+ * since the direct component is handled separately.  Therefore, any
+ * ambient ray which hits an active light source must be discarded.
+ * The same is true for stray specular samples, since the specular
+ * contribution from light sources is calculated separately.
+ */
+
+#define  badcomponent(m, r)	(r->crtype&(AMBIENT|SPECULAR) && \
+				!(r->crtype&SHADOW || r->rod < 0.0 || \
+		/* not 100% correct */	distglow(m, r, r->rot)))
+
+/* passillum *
+ *
+ * An illum passes to another material type when we didn't hit it
+ * on purpose (as part of a direct calculation), or it is relaying
+ * a virtual light source.
+ */
+
+#define  passillum(m, r)	(m->otype==MAT_ILLUM && \
+				(r->rsrc<0 || source[r->rsrc].so!=r->ro || \
+				source[r->rsrc].sflags&SVIRTUAL))
+
+/* srcignore *
+ *
+ * The -dv flag is normally on for sources to be visible.
+ */
+
+#define  srcignore(m, r)	!(directvis || r->crtype&SHADOW || \
+				distglow(m, r, raydist(r,PRIMARY)))
+
+
+extern int
+m_light(				/* ray hit a light source */
+	register OBJREC  *m,
+	register RAY  *r
+)
+{
+						/* check for over-counting */
+	if (badcomponent(m, r))
+		return(1);
+	if (wrongsource(m, r))
+		return(1);
+						/* check for passed illum */
+	if (passillum(m, r)) {
+		if (m->oargs.nsargs && strcmp(m->oargs.sarg[0], VOIDID))
+			return(rayshade(r,lastmod(objndx(m),m->oargs.sarg[0])));
+		raytrans(r);
+		return(1);
+	}
+					/* otherwise treat as source */
+						/* check for behind */
+	if (r->rod < 0.0)
+		return(1);
+						/* check for invisibility */
+	if (srcignore(m, r))
+		return(1);
+						/* check for outside spot */
+	if (m->otype==MAT_SPOT && spotout(r, makespot(m)))
+		return(1);
+						/* get distribution pattern */
+	raytexture(r, m->omod);
+						/* get source color */
+	setcolor(r->rcol, m->oargs.farg[0],
+			  m->oargs.farg[1],
+			  m->oargs.farg[2]);
+						/* modify value */
+	multcolor(r->rcol, r->pcol);
+	return(1);
 }