--- ray/src/rt/raytrace.c	1996/04/17 14:06:35	2.26
+++ ray/src/rt/raytrace.c	2015/05/21 15:28:24	2.67
@@ -1,59 +1,59 @@
-/* Copyright (c) 1996 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char RCSid[] = "$Id: raytrace.c,v 2.67 2015/05/21 15:28:24 greg Exp $";
 #endif
-
 /*
  *  raytrace.c - routines for tracing and shading rays.
  *
- *     8/7/85
+ *  External symbols declared in ray.h
  */
 
-#include  "ray.h"
+#include "copyright.h"
 
-#include  "octree.h"
-
+#include  "ray.h"
+#include  "source.h"
 #include  "otypes.h"
-
 #include  "otspecial.h"
+#include  "random.h"
+#include  "pmap.h"
 
 #define  MAXCSET	((MAXSET+1)*2-1)	/* maximum check set size */
 
-extern CUBE  thescene;			/* our scene */
-extern int  maxdepth;			/* maximum recursion depth */
-extern double  minweight;		/* minimum ray weight */
-extern int  do_irrad;			/* compute irradiance? */
-extern COLOR  ambval;			/* ambient value */
+RNUMBER  raynum = 0;		/* next unique ray number */
+RNUMBER  nrays = 0;		/* number of calls to localhit */
 
-extern COLOR  cextinction;		/* global extinction coefficient */
-extern COLOR  salbedo;			/* global scattering albedo */
-extern double  seccg;			/* global scattering eccentricity */
-extern double  ssampdist;		/* scatter sampling distance */
-
-unsigned long  raynum = 0;		/* next unique ray number */
-unsigned long  nrays = 0;		/* number of calls to localhit */
-
-static FLOAT  Lambfa[5] = {PI, PI, PI, 0.0, 0.0};
+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 */
 
-static int  raymove(), checkset(), checkhit();
-
-#define  MAXLOOP	128		/* modifier loop detection */
-
 #define  RAYHIT		(-1)		/* return value for intercepted ray */
 
+static int raymove(FVECT  pos, OBJECT  *cxs, int  dirf, RAY  *r, CUBE  *cu);
+static int checkhit(RAY  *r, CUBE  *cu, OBJECT  *cxs);
+static void checkset(OBJECT  *os, OBJECT  *cs);
 
-rayorigin(r, ro, rt, rw)		/* start new ray from old one */
-register RAY  *r, *ro;
-int  rt;
-double  rw;
+
+int
+rayorigin(		/* start new ray from old one */
+	RAY  *r,
+	int  rt,
+	const RAY  *ro,
+	const COLOR rc
+)
 {
+	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;
@@ -66,6 +66,10 @@ double  rw;
 		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++;
@@ -82,34 +86,72 @@ double  rw;
 		copycolor(r->albedo, ro->albedo);
 		r->gecc = ro->gecc;
 		r->slights = ro->slights;
-		r->rweight = ro->rweight * rw;
 		r->crtype = ro->crtype | (r->rtype = rt);
 		VCOPY(r->rorg, ro->rop);
+		r->rweight = ro->rweight * rw;
+						/* 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);
+		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);
+						/* ambient in photon map? */
+	if (r->crtype & AMBIENT && photonMapping)
+		return(-1);
+	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);
 }
 
 
-rayclear(r)			/* clear a ray for (re)evaluation */
-register RAY  *r;
+void
+rayclear(			/* clear a ray for (re)evaluation */
+	RAY  *r
+)
 {
 	r->rno = raynum++;
 	r->newcset = r->clipset;
+	r->hitf = rayhit;
+	r->robj = OVOID;
 	r->ro = NULL;
-	r->rot = FHUGE;
+	r->rox = NULL;
+	r->rt = r->rot = FHUGE;
 	r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
+	r->uv[0] = r->uv[1] = 0.0;
 	setcolor(r->pcol, 1.0, 1.0, 1.0);
 	setcolor(r->rcol, 0.0, 0.0, 0.0);
-	r->rt = 0.0;
 }
 
 
-raytrace(r)			/* trace a ray and compute its value */
-RAY  *r;
+void
+raytrace(			/* trace a ray and compute its value */
+	RAY  *r
+)
 {
-	extern int  (*trace)();
-
 	if (localhit(r, &thescene))
 		raycont(r);		/* hit local surface, evaluate */
 	else if (r->ro == &Aftplane) {
@@ -118,15 +160,17 @@ RAY  *r;
 	} 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 */
 }
 
 
-raycont(r)			/* check for clipped object and continue */
-register RAY  *r;
+void
+raycont(			/* check for clipped object and continue */
+	RAY  *r
+)
 {
 	if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) ||
 			!rayshade(r, r->ro->omod))
@@ -134,32 +178,31 @@ register RAY  *r;
 }
 
 
-raytrans(r)			/* transmit ray as is */
-register RAY  *r;
+void
+raytrans(			/* transmit ray as is */
+	RAY  *r
+)
 {
 	RAY  tr;
 
-	if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
-		VCOPY(tr.rdir, r->rdir);
-		rayvalue(&tr);
-		copycolor(r->rcol, tr.rcol);
-		r->rt = r->rot + tr.rt;
-	}
+	rayorigin(&tr, TRANS, r, NULL);		/* always continue */
+	VCOPY(tr.rdir, r->rdir);
+	rayvalue(&tr);
+	copycolor(r->rcol, tr.rcol);
+	r->rt = r->rot + tr.rt;
 }
 
 
-rayshade(r, mod)		/* shade ray r with material mod */
-register RAY  *r;
-int  mod;
+int
+rayshade(		/* shade ray r with material mod */
+	RAY  *r,
+	int  mod
+)
 {
-	static int  depth = 0;
-	int  gotmat;
-	register OBJREC  *m;
-					/* check for infinite loop */
-	if (depth++ >= MAXLOOP)
-		objerror(r->ro, USER, "possible modifier loop");
+	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)) {
@@ -168,66 +211,68 @@ int  mod;
 		}
 		******/
 					/* hack for irradiance calculation */
-		if (do_irrad && !(r->crtype & ~(PRIMARY|TRANS))) {
+		if (do_irrad && !(r->crtype & ~(PRIMARY|TRANS)) &&
+				m->otype != MAT_CLIP &&
+				(ofun[m->otype].flags & (T_M|T_X))) {
 			if (irr_ignore(m->otype)) {
-				depth--;
 				raytrans(r);
 				return(1);
 			}
 			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() */
 	}
-	depth--;
-	return(gotmat);
+	return(0);			/* no material! */
 }
 
 
-rayparticipate(r)			/* compute ray medium participation */
-register RAY  *r;
+void
+rayparticipate(			/* compute ray medium participation */
+	RAY  *r
+)
 {
 	COLOR	ce, ca;
-	double	dist;
 	double	re, ge, be;
 
 	if (intens(r->cext) <= 1./FHUGE)
 		return;				/* no medium */
-	if ((dist = r->rot) >= FHUGE)
-		dist = 2.*thescene.cusize;	/* what to use for infinity? */
-	re = dist*colval(r->cext,RED);
-	ge = dist*colval(r->cext,GRN);
-	be = dist*colval(r->cext,BLU);
+	re = r->rot*colval(r->cext,RED);
+	ge = r->rot*colval(r->cext,GRN);
+	be = r->rot*colval(r->cext,BLU);
 	if (r->crtype & SHADOW) {		/* no scattering for sources */
 		re *= 1. - colval(r->albedo,RED);
 		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,
-		colval(r->albedo,RED)*colval(ambval,RED)*(1.-colval(ce,RED)),
-		colval(r->albedo,GRN)*colval(ambval,GRN)*(1.-colval(ce,GRN)),
-		colval(r->albedo,BLU)*colval(ambval,BLU)*(1.-colval(ce,BLU)));
-	addcolor(r->rcol, ca);			/* ambient in scattering */
+	
+	/* PMAP: indirect inscattering accounted for by volume photons? */
+	if (!volumePhotonMapping) {
+		setcolor(ca,
+			colval(r->albedo,RED)*colval(ambval,RED)*(1.-colval(ce,RED)),
+			colval(r->albedo,GRN)*colval(ambval,GRN)*(1.-colval(ce,GRN)),
+			colval(r->albedo,BLU)*colval(ambval,BLU)*(1.-colval(ce,BLU)));
+		addcolor(r->rcol, ca);			/* ambient in scattering */
+	}
+	
 	srcscatter(r);				/* source in scattering */
 }
 
 
-raytexture(r, mod)			/* get material modifiers */
-RAY  *r;
-int  mod;
+void
+raytexture(			/* get material modifiers */
+	RAY  *r,
+	OBJECT  mod
+)
 {
-	static int  depth = 0;
-	register OBJREC  *m;
-					/* check for infinite loop */
-	if (depth++ >= MAXLOOP)
-		objerror(r->ro, USER, "modifier loop");
+	OBJREC  *m;
 					/* execute textures and patterns */
 	for ( ; mod != OVOID; mod = m->omod) {
 		m = objptr(mod);
@@ -243,18 +288,20 @@ int  mod;
 			objerror(r->ro, USER, errmsg);
 		}
 	}
-	depth--;			/* end here */
 }
 
 
-raymixture(r, fore, back, coef)		/* mix modifiers */
-register RAY  *r;
-OBJECT  fore, back;
-double  coef;
+int
+raymixture(		/* mix modifiers */
+	RAY  *r,
+	OBJECT  fore,
+	OBJECT  back,
+	double  coef
+)
 {
 	RAY  fr, br;
 	int  foremat, backmat;
-	register int  i;
+	int  i;
 					/* bound coefficient */
 	if (coef > 1.0)
 		coef = 1.0;
@@ -263,19 +310,26 @@ double  coef;
 					/* compute foreground and background */
 	foremat = backmat = 0;
 					/* foreground */
-	copystruct(&fr, r);
-	if (coef > FTINY)
+	fr = *r;
+	if (coef > FTINY) {
+		fr.rweight *= coef;
+		scalecolor(fr.rcoef, coef);
 		foremat = rayshade(&fr, fore);
+	}
 					/* background */
-	copystruct(&br, r);
-	if (coef < 1.0-FTINY)
+	br = *r;
+	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)
+	if (backmat ^ foremat) {
+		if (backmat && coef > FTINY)
 			raytrans(&fr);
-		else
+		else if (foremat && coef < 1.0-FTINY)
 			raytrans(&br);
+	}
 					/* mix perturbations */
 	for (i = 0; i < 3; i++)
 		r->pert[i] = coef*fr.pert[i] + (1.0-coef)*br.pert[i];
@@ -298,9 +352,10 @@ double  coef;
 
 
 double
-raydist(r, flags)		/* compute (cumulative) ray distance */
-register RAY  *r;
-register int  flags;
+raydist(		/* compute (cumulative) ray distance */
+	const RAY  *r,
+	int  flags
+)
 {
 	double  sum = 0.0;
 
@@ -312,13 +367,40 @@ register int  flags;
 }
 
 
+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]);
+}
+
+
 double
-raynormal(norm, r)		/* compute perturbed normal for ray */
-FVECT  norm;
-register RAY  *r;
+raynormal(		/* compute perturbed normal for ray */
+	FVECT  norm,
+	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
@@ -347,15 +429,17 @@ register RAY  *r;
 }
 
 
-newrayxf(r)			/* get new tranformation matrix for ray */
-RAY  *r;
+void
+newrayxf(			/* get new tranformation matrix for ray */
+	RAY  *r
+)
 {
 	static struct xfn {
 		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
@@ -383,8 +467,10 @@ RAY  *r;
 }
 
 
-flipsurface(r)			/* reverse surface orientation */
-register RAY  *r;
+void
+flipsurface(			/* reverse surface orientation */
+	RAY  *r
+)
 {
 	r->rod = -r->rod;
 	r->ron[0] = -r->ron[0];
@@ -396,15 +482,34 @@ register RAY  *r;
 }
 
 
-localhit(r, scene)		/* check for hit in the octree */
-register RAY  *r;
-register CUBE  *scene;
+void
+rayhit(			/* standard ray hit test */
+	OBJECT  *oset,
+	RAY  *r
+)
 {
+	OBJREC  *o;
+	int	i;
+
+	for (i = oset[0]; i > 0; i--) {
+		o = objptr(oset[i]);
+		if ((*ofun[o->otype].funp)(o, r))
+			r->robj = oset[i];
+	}
+}
+
+
+int
+localhit(		/* check for hit in the octree */
+	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;
@@ -415,14 +520,15 @@ register CUBE  *scene;
 		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;
@@ -445,32 +551,32 @@ register CUBE  *scene;
 		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);
 	}
 	cxset[0] = 0;
 	raymove(curpos, cxset, sflags, r, scene);
-	return(r->ro != NULL & r->ro != &Aftplane);
+	return((r->ro != NULL) & (r->ro != &Aftplane));
 }
 
 
 static int
-raymove(pos, cxs, dirf, r, cu)		/* 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;
+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 */
+	RAY  *r,
+	CUBE  *cu
+)
 {
 	int  ax;
 	double  dt, t;
 
 	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);
@@ -536,43 +642,40 @@ register CUBE  *cu;
 			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
-checkhit(r, cu, cxs)		/* check for hit in full cube */
-register RAY  *r;
-CUBE  *cu;
-OBJECT  *cxs;
+static int
+checkhit(		/* check for hit in full cube */
+	RAY  *r,
+	CUBE  *cu,
+	OBJECT  *cxs
+)
 {
 	OBJECT  oset[MAXSET+1];
-	register OBJREC  *o;
-	register int  i;
 
 	objset(oset, cu->cutree);
-	checkset(oset, cxs);			/* eliminate double-checking */
-	for (i = oset[0]; i > 0; i--) {
-		o = objptr(oset[i]);
-		(*ofun[o->otype].funp)(o, r);
-	}
-	if (r->ro == NULL)
+	checkset(oset, cxs);			/* avoid double-checking */
+
+	(*r->hitf)(oset, r);			/* test for hit in set */
+
+	if (r->robj == OVOID)
 		return(0);			/* no scores yet */
 
 	return(incube(cu, r->rop));		/* hit OK if in current cube */
 }
 
 
-static
-checkset(os, cs)		/* modify checked set and set to check */
-register OBJECT  *os;			/* os' = os - cs */
-register OBJECT  *cs;			/* cs' = cs + os */
+static void
+checkset(		/* modify checked set and set to check */
+	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;