--- ray/src/rt/source.c	1993/04/06 17:55:51	2.11
+++ ray/src/rt/source.c	1998/08/10 18:37:56	2.28
@@ -1,7 +1,7 @@
-/* Copyright (c) 1993 Regents of the University of California */
+/* Copyright (c) 1998 Silicon Graphics, Inc. */
 
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static char SCCSid[] = "$SunId$ SGI";
 #endif
 
 /*
@@ -18,6 +18,14 @@ static char SCCSid[] = "$SunId$ LBL";
 
 #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()
  */
@@ -68,6 +76,9 @@ 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)
@@ -128,7 +139,7 @@ SRCINDEX  *si;			/* source sample index */
 	sr->rsrc = si->sn;			/* remember source */
 	srcp = source + si->sn;
 	if (srcp->sflags & SDISTANT) {
-		if (srcp->sflags & SSPOT && spotout(sr, srcp->sl.s, 1))
+		if (srcp->sflags & SSPOT && spotout(sr, srcp->sl.s))
 			continue;
 		return(1);		/* sample OK */
 	}
@@ -138,7 +149,7 @@ SRCINDEX  *si;			/* source sample index */
 		continue;
 						/* check angle */
 	if (srcp->sflags & SSPOT) {
-		if (spotout(sr, srcp->sl.s, 0))
+		if (spotout(sr, srcp->sl.s))
 			continue;
 					/* adjust solid angle */
 		si->dom *= d*d;
@@ -152,7 +163,7 @@ SRCINDEX  *si;			/* source sample index */
 
 
 srcvalue(r)			/* punch ray to source and compute value */
-RAY  *r;
+register RAY  *r;
 {
 	register SRCREC  *sp;
 
@@ -161,7 +172,9 @@ 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 */
@@ -169,9 +182,12 @@ 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;
@@ -180,6 +196,9 @@ 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");
 }
 
 
@@ -208,6 +227,7 @@ register RAY  *r;
 			}
 
 	if (r->ro != NULL) {
+		r->robj = objndx(r->ro);
 		for (i = 0; i < 3; i++)
 			r->ron[i] = -r->rdir[i];
 		r->rod = 1.0;
@@ -299,8 +319,10 @@ char  *p;			/* data for f */
 						/* 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)
@@ -317,6 +339,7 @@ char  *p;			/* data for f */
 				source[scp->sno].sflags & SFOLLOW )) {
 						/* follow entire path */
 			raycont(&sr);
+			rayparticipate(&sr);
 			if (trace != NULL)
 				(*trace)(&sr);	/* trace execution */
 			if (bright(sr.rcol) <= FTINY)
@@ -329,13 +352,13 @@ char  *p;			/* data for f */
 		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
@@ -344,12 +367,87 @@ char  *p;			/* data for f */
 		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);
 	}
 }
 
 
+srcscatter(r)			/* 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 */
+			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)
+				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.
@@ -371,6 +469,7 @@ static int weaksrcmod(obj) int obj;	/* efficiency boos
 return(o->otype==MAT_ILLUM|o->otype==MAT_GLOW);}
 
 #define  illumblock(m, r)	(!(source[r->rsrc].sflags&SVIRTUAL) && \
+				r->rod > 0.0 && \
 				weaksrcmod(source[r->rsrc].so->omod))
 
 /* wrongsource *
@@ -390,9 +489,9 @@ return(o->otype==MAT_ILLUM|o->otype==MAT_GLOW);}
  * (Glows with negative radii should NEVER participate in illumination.)
  */
 
-#define  distglow(m, r)		(m->otype==MAT_GLOW && \
+#define  distglow(m, r, d)	(m->otype==MAT_GLOW && \
 				m->oargs.farg[3] >= -FTINY && \
-				r->rot > m->oargs.farg[3])
+				d > m->oargs.farg[3])
 
 /* badcomponent *
  *
@@ -405,15 +504,8 @@ return(o->otype==MAT_ILLUM|o->otype==MAT_GLOW);}
 
 #define  badcomponent(m, r)	(r->crtype&(AMBIENT|SPECULAR) && \
 				!(r->crtype&SHADOW || r->rod < 0.0 || \
-					distglow(m, r)))
+		/* not 100% correct */	distglow(m, r, r->rot)))
 
-/* overcount *
- *
- * All overcounting possibilities are contained here.
- */
-
-#define  overcount(m, r)	(badcomponent(m,r) || wrongsource(m,r))
-
 /* passillum *
  *
  * An illum passes to another material type when we didn't hit it
@@ -430,8 +522,8 @@ return(o->otype==MAT_ILLUM|o->otype==MAT_GLOW);}
  * The -dv flag is normally on for sources to be visible.
  */
 
-#define  srcignore(m, r)	(!directvis && !(r->crtype&SHADOW) && \
-				!distglow(m, r))
+#define  srcignore(m, r)	!(directvis || r->crtype&SHADOW || \
+				distglow(m, r, raydist(r,PRIMARY)))
 
 
 m_light(m, r)			/* ray hit a light source */
@@ -439,26 +531,27 @@ register OBJREC  *m;
 register RAY  *r;
 {
 						/* check for over-counting */
-	if (overcount(m, r))
-		return;
+	if (badcomponent(m, r))
+		return(1);
+	if (wrongsource(m, r))
+		return(1);
 						/* check for passed illum */
 	if (passillum(m, r)) {
-		if (m->oargs.nsargs < 1 || !strcmp(m->oargs.sarg[0], VOIDID))
-			raytrans(r);
-		else
-			rayshade(r, modifier(m->oargs.sarg[0]));
-		return;
+		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;
+		return(1);
 						/* check for invisibility */
 	if (srcignore(m, r))
-		return;
+		return(1);
 						/* check for outside spot */
-	if (m->otype==MAT_SPOT && spotout(r, makespot(m), r->rot>=FHUGE))
-		return;
+	if (m->otype==MAT_SPOT && spotout(r, makespot(m)))
+		return(1);
 						/* get distribution pattern */
 	raytexture(r, m->omod);
 						/* get source color */
@@ -467,4 +560,5 @@ register RAY  *r;
 			  m->oargs.farg[2]);
 						/* modify value */
 	multcolor(r->rcol, r->pcol);
+	return(1);
 }