--- ray/src/rt/raytrace.c	2004/03/30 16:13:01	2.45
+++ ray/src/rt/raytrace.c	2012/06/01 19:17:17	2.64
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: raytrace.c,v 2.45 2004/03/30 16:13:01 schorsch Exp $";
+static const char RCSid[] = "$Id: raytrace.c,v 2.64 2012/06/01 19:17:17 greg Exp $";
 #endif
 /*
  *  raytrace.c - routines for tracing and shading rays.
@@ -13,16 +13,17 @@ static const char RCSid[] = "$Id: raytrace.c,v 2.45 20
 #include  "source.h"
 #include  "otypes.h"
 #include  "otspecial.h"
+#include  "random.h"
 
 #define  MAXCSET	((MAXSET+1)*2-1)	/* maximum check set size */
 
-unsigned long  raynum = 0;		/* next unique ray number */
-unsigned long  nrays = 0;		/* number of calls to localhit */
+RNUMBER  raynum = 0;		/* next unique ray number */
+RNUMBER  nrays = 0;		/* number of calls to localhit */
 
 static RREAL  Lambfa[5] = {PI, PI, PI, 0.0, 0.0};
 OBJREC  Lamb = {
 	OVOID, MAT_PLASTIC, "Lambertian",
-	{0, 5, NULL, Lambfa}, NULL,
+	{NULL, Lambfa, 0, 5}, NULL
 };					/* a Lambertian surface */
 
 OBJREC  Aftplane;			/* aft clipping plane object */
@@ -36,14 +37,22 @@ static void checkset(OBJECT  *os, OBJECT  *cs);
 
 extern int
 rayorigin(		/* start new ray from old one */
-	register RAY  *r,
-	register RAY  *ro,
+	RAY  *r,
 	int  rt,
-	double  rw
+	const RAY  *ro,
+	const COLOR rc
 )
 {
-	double	re;
-
+	double	rw, re;
+						/* assign coefficient/weight */
+	if (rc == NULL) {
+		rw = 1.0;
+		setcolor(r->rcoef, 1., 1., 1.);
+	} else {
+		rw = intens(rc);
+		if (rc != r->rcoef)
+			copycolor(r->rcoef, rc);
+	}
 	if ((r->parent = ro) == NULL) {		/* primary ray */
 		r->rlvl = 0;
 		r->rweight = rw;
@@ -56,6 +65,10 @@ rayorigin(		/* start new ray from old one */
 		r->gecc = seccg;
 		r->slights = NULL;
 	} else {				/* spawned ray */
+		if (ro->rot >= FHUGE) {
+			memset(r, 0, sizeof(RAY));
+			return(-1);		/* illegal continuation */
+		}
 		r->rlvl = ro->rlvl;
 		if (rt & RAYREFL) {
 			r->rlvl++;
@@ -75,21 +88,45 @@ rayorigin(		/* start new ray from old one */
 		r->crtype = ro->crtype | (r->rtype = rt);
 		VCOPY(r->rorg, ro->rop);
 		r->rweight = ro->rweight * rw;
-						/* estimate absorption */
+						/* estimate extinction */
 		re = colval(ro->cext,RED) < colval(ro->cext,GRN) ?
 				colval(ro->cext,RED) : colval(ro->cext,GRN);
 		if (colval(ro->cext,BLU) < re) re = colval(ro->cext,BLU);
-		if (re > 0.)
-			r->rweight *= exp(-re*ro->rot);
+		re *= ro->rot;
+		if (re > 0.1) {
+			if (re > 92.) {
+				r->rweight = 0.0;
+			} else {
+				r->rweight *= exp(-re);
+			}
+		}
 	}
 	rayclear(r);
-	return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
+	if (r->rweight <= 0.0)			/* check for expiration */
+		return(-1);
+	if (r->crtype & SHADOW)			/* shadow commitment */
+		return(0);
+	if (maxdepth <= 0 && rc != NULL) {	/* Russian roulette */
+		if (minweight <= 0.0)
+			error(USER, "zero ray weight in Russian roulette");
+		if (maxdepth < 0 && r->rlvl > -maxdepth)
+			return(-1);		/* upper reflection limit */
+		if (r->rweight >= minweight)
+			return(0);
+		if (frandom() > r->rweight/minweight)
+			return(-1);
+		rw = minweight/r->rweight;	/* promote survivor */
+		scalecolor(r->rcoef, rw);
+		r->rweight = minweight;
+		return(0);
+	}
+	return(r->rweight >= minweight && r->rlvl <= abs(maxdepth) ? 0 : -1);
 }
 
 
 extern void
 rayclear(			/* clear a ray for (re)evaluation */
-	register RAY  *r
+	RAY  *r
 )
 {
 	r->rno = raynum++;
@@ -119,16 +156,16 @@ raytrace(			/* trace a ray and compute its value */
 	} else if (sourcehit(r))
 		rayshade(r, r->ro->omod);	/* distant source */
 
-	rayparticipate(r);		/* for participating medium */
-
 	if (trace != NULL)
 		(*trace)(r);		/* trace execution */
+
+	rayparticipate(r);		/* for participating medium */
 }
 
 
 extern void
 raycont(			/* check for clipped object and continue */
-	register RAY  *r
+	RAY  *r
 )
 {
 	if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) ||
@@ -139,12 +176,12 @@ raycont(			/* check for clipped object and continue */
 
 extern void
 raytrans(			/* transmit ray as is */
-	register RAY  *r
+	RAY  *r
 )
 {
 	RAY  tr;
 
-	if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
+	if (rayorigin(&tr, TRANS, r, NULL) == 0) {
 		VCOPY(tr.rdir, r->rdir);
 		rayvalue(&tr);
 		copycolor(r->rcol, tr.rcol);
@@ -155,14 +192,14 @@ raytrans(			/* transmit ray as is */
 
 extern int
 rayshade(		/* shade ray r with material mod */
-	register RAY  *r,
+	RAY  *r,
 	int  mod
 )
 {
-	int  gotmat;
-	register OBJREC  *m;
+	OBJREC  *m;
+
 	r->rt = r->rot;			/* set effective ray length */
-	for (gotmat = 0; !gotmat && mod != OVOID; mod = m->omod) {
+	for ( ; mod != OVOID; mod = m->omod) {
 		m = objptr(mod);
 		/****** unnecessary test since modifier() is always called
 		if (!ismodifier(m->otype)) {
@@ -181,16 +218,16 @@ rayshade(		/* shade ray r with material mod */
 			if (!islight(m->otype))
 				m = &Lamb;
 		}
-					/* materials call raytexture */
-		gotmat = (*ofun[m->otype].funp)(m, r);
+		if ((*ofun[m->otype].funp)(m, r))
+			return(1);	/* materials call raytexture() */
 	}
-	return(gotmat);
+	return(0);			/* no material! */
 }
 
 
 extern void
 rayparticipate(			/* compute ray medium participation */
-	register RAY  *r
+	RAY  *r
 )
 {
 	COLOR	ce, ca;
@@ -206,10 +243,10 @@ rayparticipate(			/* compute ray medium participation 
 		ge *= 1. - colval(r->albedo,GRN);
 		be *= 1. - colval(r->albedo,BLU);
 	}
-	setcolor(ce,	re<=0. ? 1. : re>92. ? 0. : exp(-re),
-			ge<=0. ? 1. : ge>92. ? 0. : exp(-ge),
-			be<=0. ? 1. : be>92. ? 0. : exp(-be));
-	multcolor(r->rcol, ce);			/* path absorption */
+	setcolor(ce,	re<=FTINY ? 1. : re>92. ? 0. : exp(-re),
+			ge<=FTINY ? 1. : ge>92. ? 0. : exp(-ge),
+			be<=FTINY ? 1. : be>92. ? 0. : exp(-be));
+	multcolor(r->rcol, ce);			/* path extinction */
 	if (r->crtype & SHADOW || intens(r->albedo) <= FTINY)
 		return;				/* no scattering */
 	setcolor(ca,
@@ -227,7 +264,7 @@ raytexture(			/* get material modifiers */
 	OBJECT  mod
 )
 {
-	register OBJREC  *m;
+	OBJREC  *m;
 					/* execute textures and patterns */
 	for ( ; mod != OVOID; mod = m->omod) {
 		m = objptr(mod);
@@ -248,7 +285,7 @@ raytexture(			/* get material modifiers */
 
 extern int
 raymixture(		/* mix modifiers */
-	register RAY  *r,
+	RAY  *r,
 	OBJECT  fore,
 	OBJECT  back,
 	double  coef
@@ -256,7 +293,7 @@ raymixture(		/* mix modifiers */
 {
 	RAY  fr, br;
 	int  foremat, backmat;
-	register int  i;
+	int  i;
 					/* bound coefficient */
 	if (coef > 1.0)
 		coef = 1.0;
@@ -266,12 +303,18 @@ raymixture(		/* mix modifiers */
 	foremat = backmat = 0;
 					/* foreground */
 	fr = *r;
-	if (coef > FTINY)
+	if (coef > FTINY) {
+		fr.rweight *= coef;
+		scalecolor(fr.rcoef, coef);
 		foremat = rayshade(&fr, fore);
+	}
 					/* background */
 	br = *r;
-	if (coef < 1.0-FTINY)
+	if (coef < 1.0-FTINY) {
+		br.rweight *= 1.0-coef;
+		scalecolor(br.rcoef, 1.0-coef);
 		backmat = rayshade(&br, back);
+	}
 					/* check for transparency */
 	if (backmat ^ foremat) {
 		if (backmat && coef > FTINY)
@@ -302,8 +345,8 @@ raymixture(		/* mix modifiers */
 
 extern double
 raydist(		/* compute (cumulative) ray distance */
-	register RAY  *r,
-	register int  flags
+	const RAY  *r,
+	int  flags
 )
 {
 	double  sum = 0.0;
@@ -316,14 +359,40 @@ raydist(		/* compute (cumulative) ray distance */
 }
 
 
+extern void
+raycontrib(		/* compute (cumulative) ray contribution */
+	RREAL  rc[3],
+	const RAY  *r,
+	int  flags
+)
+{
+	double	eext[3];
+	int	i;
+
+	eext[0] = eext[1] = eext[2] = 0.;
+	rc[0] = rc[1] = rc[2] = 1.;
+
+	while (r != NULL && r->crtype&flags) {
+		for (i = 3; i--; ) {
+			rc[i] *= colval(r->rcoef,i);
+			eext[i] += r->rot * colval(r->cext,i);
+		}
+		r = r->parent;
+	}
+	for (i = 3; i--; )
+		rc[i] *= (eext[i] <= FTINY) ? 1. :
+				(eext[i] > 92.) ? 0. : exp(-eext[i]);
+}
+
+
 extern double
 raynormal(		/* compute perturbed normal for ray */
 	FVECT  norm,
-	register RAY  *r
+	RAY  *r
 )
 {
 	double  newdot;
-	register int  i;
+	int  i;
 
 	/*	The perturbation is added to the surface normal to obtain
 	 *  the new normal.  If the new normal would affect the surface
@@ -361,8 +430,8 @@ newrayxf(			/* get new tranformation matrix for ray */
 		struct xfn  *next;
 		FULLXF  xf;
 	}  xfseed = { &xfseed }, *xflast = &xfseed;
-	register struct xfn  *xp;
-	register RAY  *rp;
+	struct xfn  *xp;
+	const RAY  *rp;
 
 	/*
 	 * Search for transform in circular list that
@@ -373,7 +442,7 @@ newrayxf(			/* get new tranformation matrix for ray */
 		if (rp->rox == &xp->xf) {		/* xp in use */
 			xp = xp->next;			/* move to next */
 			if (xp == xflast) {		/* need new one */
-				xp = (struct xfn *)malloc(sizeof(struct xfn));
+				xp = (struct xfn *)bmalloc(sizeof(struct xfn));
 				if (xp == NULL)
 					error(SYSTEM,
 						"out of memory in newrayxf");
@@ -392,7 +461,7 @@ newrayxf(			/* get new tranformation matrix for ray */
 
 extern void
 flipsurface(			/* reverse surface orientation */
-	register RAY  *r
+	RAY  *r
 )
 {
 	r->rod = -r->rod;
@@ -424,15 +493,15 @@ rayhit(			/* standard ray hit test */
 
 extern int
 localhit(		/* check for hit in the octree */
-	register RAY  *r,
-	register CUBE  *scene
+	RAY  *r,
+	CUBE  *scene
 )
 {
 	OBJECT  cxset[MAXCSET+1];	/* set of checked objects */
 	FVECT  curpos;			/* current cube position */
 	int  sflags;			/* sign flags */
 	double  t, dt;
-	register int  i;
+	int  i;
 
 	nrays++;			/* increment trace counter */
 	sflags = 0;
@@ -443,14 +512,15 @@ localhit(		/* check for hit in the octree */
 		else if (r->rdir[i] < -1e-7)
 			sflags |= 0x10 << i;
 	}
-	if (sflags == 0)
-		error(CONSISTENCY, "zero ray direction in localhit");
+	if (!sflags) {
+		error(WARNING, "zero ray direction in localhit");
+		return(0);
+	}
 					/* start off assuming nothing hit */
 	if (r->rmax > FTINY) {		/* except aft plane if one */
 		r->ro = &Aftplane;
 		r->rot = r->rmax;
-		for (i = 0; i < 3; i++)
-			r->rop[i] = r->rorg[i] + r->rot*r->rdir[i];
+		VSUM(r->rop, r->rorg, r->rdir, r->rot);
 	}
 					/* find global cube entrance point */
 	t = 0.0;
@@ -473,8 +543,7 @@ localhit(		/* check for hit in the octree */
 		if (t >= r->rot)	/* clipped already */
 			return(0);
 					/* advance position */
-		for (i = 0; i < 3; i++)
-			curpos[i] += r->rdir[i]*t;
+		VSUM(curpos, curpos, r->rdir, t);
 
 		if (!incube(scene, curpos))	/* non-intersecting ray */
 			return(0);
@@ -490,8 +559,8 @@ raymove(		/* check for hit as we move */
 	FVECT  pos,			/* current position, modified herein */
 	OBJECT  *cxs,			/* checked objects, modified by checkhit */
 	int  dirf,			/* direction indicators to speed tests */
-	register RAY  *r,
-	register CUBE  *cu
+	RAY  *r,
+	CUBE  *cu
 )
 {
 	int  ax;
@@ -499,7 +568,7 @@ raymove(		/* check for hit as we move */
 
 	if (istree(cu->cutree)) {		/* recurse on subcubes */
 		CUBE  cukid;
-		register int  br, sgn;
+		int  br, sgn;
 
 		cukid.cusize = cu->cusize * 0.5;	/* find subcube */
 		VCOPY(cukid.cuorg, cu->cuorg);
@@ -565,16 +634,14 @@ raymove(		/* check for hit as we move */
 			ax = 2;
 		}
 	}
-	pos[0] += r->rdir[0]*t;
-	pos[1] += r->rdir[1]*t;
-	pos[2] += r->rdir[2]*t;
+	VSUM(pos, pos, r->rdir, t);
 	return(ax);
 }
 
 
 static int
 checkhit(		/* check for hit in full cube */
-	register RAY  *r,
+	RAY  *r,
 	CUBE  *cu,
 	OBJECT  *cxs
 )
@@ -595,12 +662,12 @@ checkhit(		/* check for hit in full cube */
 
 static void
 checkset(		/* modify checked set and set to check */
-	register OBJECT  *os,			/* os' = os - cs */
-	register OBJECT  *cs			/* cs' = cs + os */
+	OBJECT  *os,			/* os' = os - cs */
+	OBJECT  *cs			/* cs' = cs + os */
 )
 {
 	OBJECT  cset[MAXCSET+MAXSET+1];
-	register int  i, j;
+	int  i, j;
 	int  k;
 					/* copy os in place, cset <- cs */
 	cset[0] = 0;