--- ray/src/rt/ambcomp.c	1992/03/04 16:28:25	2.3
+++ ray/src/rt/ambcomp.c	2005/04/19 01:15:06	2.14
@@ -1,64 +1,67 @@
-/* Copyright (c) 1991 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char	RCSid[] = "$Id: ambcomp.c,v 2.14 2005/04/19 01:15:06 greg Exp $";
 #endif
-
 /*
  * Routines to compute "ambient" values using Monte Carlo
+ *
+ *  Declarations of external symbols in ambient.h
  */
 
+#include "copyright.h"
+
 #include  "ray.h"
 
 #include  "ambient.h"
 
 #include  "random.h"
 
-typedef struct {
-	short  t, p;		/* theta, phi indices */
-	COLOR  v;		/* value sum */
-	float  r;		/* 1/distance sum */
-	float  k;		/* variance for this division */
-	int  n;			/* number of subsamples */
-}  AMBSAMP;		/* ambient sample division */
 
-typedef struct {
-	FVECT  ux, uy, uz;	/* x, y and z axis directions */
-	short  nt, np;		/* number of theta and phi directions */
-}  AMBHEMI;		/* ambient sample hemisphere */
-
-extern double  sin(), cos(), sqrt();
-
-
-static int
-ambcmp(d1, d2)				/* decreasing order */
-AMBSAMP  *d1, *d2;
+int
+inithemi(			/* initialize sampling hemisphere */
+	register AMBHEMI  *hp,
+	RAY  *r,
+	COLOR ac, 
+	double  wt
+)
 {
-	if (d1->k < d2->k)
-		return(1);
-	if (d1->k > d2->k)
-		return(-1);
-	return(0);
+	int	ns;
+	double	d;
+	register int  i;
+					/* set number of divisions */
+	hp->nt = sqrt(ambdiv * wt / PI) + 0.5;
+	i = ambacc > FTINY ? 3 : 1;	/* minimum number of samples */
+	if (hp->nt < i)
+		hp->nt = i;
+	hp->np = PI * hp->nt + 0.5;
+					/* set number of super-samples */
+	ns = ambssamp * wt + 0.5;
+					/* assign coefficient */
+	d = 1.0/(hp->nt*hp->np + ns);	/* XXX weight not uniform if ns > 0 */
+	copycolor(hp->acoef, ac);
+	scalecolor(hp->acoef, d);
+					/* make axes */
+	VCOPY(hp->uz, r->ron);
+	hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
+	for (i = 0; i < 3; i++)
+		if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6)
+			break;
+	if (i >= 3)
+		error(CONSISTENCY, "bad ray direction in inithemi");
+	hp->uy[i] = 1.0;
+	fcross(hp->ux, hp->uy, hp->uz);
+	normalize(hp->ux);
+	fcross(hp->uy, hp->uz, hp->ux);
+	return(ns);
 }
 
 
-static int
-ambnorm(d1, d2)				/* standard order */
-AMBSAMP  *d1, *d2;
+int
+divsample(				/* sample a division */
+	register AMBSAMP  *dp,
+	AMBHEMI  *h,
+	RAY  *r
+)
 {
-	register int  c;
-
-	if (c = d1->t - d2->t)
-		return(c);
-	return(d1->p - d2->p);
-}
-
-
-divsample(dp, h, r)			/* sample a division */
-register AMBSAMP  *dp;
-AMBHEMI  *h;
-RAY  *r;
-{
 	RAY  ar;
 	int  hlist[3];
 	double  spt[2];
@@ -66,17 +69,22 @@ RAY  *r;
 	double  b2;
 	double  phi;
 	register int  i;
-
-	if (rayorigin(&ar, r, AMBIENT, AVGREFL) < 0)
+					/* assign coefficient */
+	if (ambacc <= FTINY)		/* no storage, so report accurately */
+		copycolor(ar.rcoef, h->acoef);
+	else				/* else lie for sake of cache */
+		setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
+	if (rayorigin(&ar, AMBIENT, r, ar.rcoef) < 0)
 		return(-1);
+	copycolor(ar.rcoef, h->acoef);	/* correct coefficient rtrace output */
 	hlist[0] = r->rno;
 	hlist[1] = dp->t;
 	hlist[2] = dp->p;
 	multisamp(spt, 2, urand(ilhash(hlist,3)+dp->n));
 	zd = sqrt((dp->t + spt[0])/h->nt);
 	phi = 2.0*PI * (dp->p + spt[1])/h->np;
-	xd = cos(phi) * zd;
-	yd = sin(phi) * zd;
+	xd = tcos(phi) * zd;
+	yd = tsin(phi) * zd;
 	zd = sqrt(1.0 - zd*zd);
 	for (i = 0; i < 3; i++)
 		ar.rdir[i] =	xd*h->ux[i] +
@@ -86,6 +94,7 @@ RAY  *r;
 	rayvalue(&ar);
 	ndims--;
 	addcolor(dp->v, ar.rcol);
+					/* use rt to improve gradient calc */
 	if (ar.rt > FTINY && ar.rt < FHUGE)
 		dp->r += 1.0/ar.rt;
 					/* (re)initialize error */
@@ -99,12 +108,48 @@ RAY  *r;
 }
 
 
+static int
+ambcmp(					/* decreasing order */
+	const void *p1,
+	const void *p2
+)
+{
+	const AMBSAMP	*d1 = (const AMBSAMP *)p1;
+	const AMBSAMP	*d2 = (const AMBSAMP *)p2;
+
+	if (d1->k < d2->k)
+		return(1);
+	if (d1->k > d2->k)
+		return(-1);
+	return(0);
+}
+
+
+static int
+ambnorm(				/* standard order */
+	const void *p1,
+	const void *p2
+)
+{
+	const AMBSAMP	*d1 = (const AMBSAMP *)p1;
+	const AMBSAMP	*d2 = (const AMBSAMP *)p2;
+	register int	c;
+
+	if ( (c = d1->t - d2->t) )
+		return(c);
+	return(d1->p - d2->p);
+}
+
+
 double
-doambient(acol, r, wt, pg, dg)		/* compute ambient component */
-COLOR  acol;
-RAY  *r;
-double  wt;
-FVECT  pg, dg;
+doambient(				/* compute ambient component */
+	COLOR  acol,
+	RAY  *r,
+	COLOR  ac,
+	double  wt,
+	FVECT  pg,
+	FVECT  dg
+)
 {
 	double  b, d;
 	AMBHEMI  hemi;
@@ -117,12 +162,11 @@ FVECT  pg, dg;
 					/* initialize color */
 	setcolor(acol, 0.0, 0.0, 0.0);
 					/* initialize hemisphere */
-	inithemi(&hemi, r, wt);
+	ns = inithemi(&hemi, r, ac, wt);
 	ndivs = hemi.nt * hemi.np;
 	if (ndivs == 0)
 		return(0.0);
-					/* set number of super-samples */
-	ns = ambssamp * wt + 0.5;
+					/* allocate super-samples */
 	if (ns > 0 || pg != NULL || dg != NULL) {
 		div = (AMBSAMP *)malloc(ndivs*sizeof(AMBSAMP));
 		if (div == NULL)
@@ -141,35 +185,37 @@ FVECT  pg, dg;
 			dp->n = 0;
 			if (divsample(dp, &hemi, r) < 0)
 				goto oopsy;
+			arad += dp->r;
 			if (div != NULL)
 				dp++;
-			else {
+			else
 				addcolor(acol, dp->v);
-				arad += dp->r;
-			}
 		}
-	if (ns > 0) {			/* perform super-sampling */
+	if (ns > 0 && arad > FTINY && ndivs/arad < minarad)
+		ns = 0;			/* close enough */
+	else if (ns > 0) {		/* else perform super-sampling */
 		comperrs(div, &hemi);			/* compute errors */
 		qsort(div, ndivs, sizeof(AMBSAMP), ambcmp);	/* sort divs */
 						/* super-sample */
 		for (i = ns; i > 0; i--) {
-			copystruct(&dnew, div);
+			dnew = *div;
 			if (divsample(&dnew, &hemi, r) < 0)
 				goto oopsy;
 							/* reinsert */
 			dp = div;
 			j = ndivs < i ? ndivs : i;
 			while (--j > 0 && dnew.k < dp[1].k) {
-				copystruct(dp, dp+1);
+				*dp = *(dp+1);
 				dp++;
 			}
-			copystruct(dp, &dnew);
+			*dp = dnew;
 		}
 		if (pg != NULL || dg != NULL)	/* restore order */
 			qsort(div, ndivs, sizeof(AMBSAMP), ambnorm);
 	}
 					/* compute returned values */
 	if (div != NULL) {
+		arad = 0.0;
 		for (i = ndivs, dp = div; i-- > 0; dp++) {
 			arad += dp->r;
 			if (dp->n > 1) {
@@ -201,7 +247,7 @@ FVECT  pg, dg;
 				for (i = 0; i < 3; i++)
 					dg[i] = 0.0;
 		}
-		free((char *)div);
+		free((void *)div);
 	}
 	b = 1.0/ndivs;
 	scalecolor(acol, b);
@@ -227,43 +273,17 @@ FVECT  pg, dg;
 	return(arad);
 oopsy:
 	if (div != NULL)
-		free((char *)div);
+		free((void *)div);
 	return(0.0);
 }
 
 
-inithemi(hp, r, wt)		/* initialize sampling hemisphere */
-register AMBHEMI  *hp;
-RAY  *r;
-double  wt;
+void
+comperrs(			/* compute initial error estimates */
+	AMBSAMP  *da,	/* assumes standard ordering */
+	register AMBHEMI  *hp
+)
 {
-	register int  i;
-					/* set number of divisions */
-	if (wt < (.25*PI)/ambdiv+FTINY) {
-		hp->nt = hp->np = 0;
-		return;			/* zero samples */
-	}
-	hp->nt = sqrt(ambdiv * wt / PI) + 0.5;
-	hp->np = PI * hp->nt + 0.5;
-					/* make axes */
-	VCOPY(hp->uz, r->ron);
-	hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
-	for (i = 0; i < 3; i++)
-		if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6)
-			break;
-	if (i >= 3)
-		error(CONSISTENCY, "bad ray direction in inithemi");
-	hp->uy[i] = 1.0;
-	fcross(hp->ux, hp->uy, hp->uz);
-	normalize(hp->ux);
-	fcross(hp->uy, hp->uz, hp->ux);
-}
-
-
-comperrs(da, hp)		/* compute initial error estimates */
-AMBSAMP  *da;		/* assumes standard ordering */
-register AMBHEMI  *hp;
-{
 	double  b, b2;
 	int  i, j;
 	register AMBSAMP  *dp;
@@ -310,10 +330,12 @@ register AMBHEMI  *hp;
 }
 
 
-posgradient(gv, da, hp)				/* compute position gradient */
-FVECT  gv;
-AMBSAMP  *da;			/* assumes standard ordering */
-register AMBHEMI  *hp;
+void
+posgradient(					/* compute position gradient */
+	FVECT  gv,
+	AMBSAMP  *da,			/* assumes standard ordering */
+	register AMBHEMI  *hp
+)
 {
 	register int  i, j;
 	double  nextsine, lastsine, b, d;
@@ -357,7 +379,7 @@ register AMBHEMI  *hp;
 		}
 		mag0 *= 2.0*PI / hp->np;
 		phi = 2.0*PI * (double)j/hp->np;
-		cosp = cos(phi); sinp = sin(phi);
+		cosp = tcos(phi); sinp = tsin(phi);
 		xd += mag0*cosp - mag1*sinp;
 		yd += mag0*sinp + mag1*cosp;
 	}
@@ -366,10 +388,12 @@ register AMBHEMI  *hp;
 }
 
 
-dirgradient(gv, da, hp)				/* compute direction gradient */
-FVECT  gv;
-AMBSAMP  *da;			/* assumes standard ordering */
-register AMBHEMI  *hp;
+void
+dirgradient(					/* compute direction gradient */
+	FVECT  gv,
+	AMBSAMP  *da,			/* assumes standard ordering */
+	register AMBHEMI  *hp
+)
 {
 	register int  i, j;
 	double  mag;
@@ -391,8 +415,8 @@ register AMBHEMI  *hp;
 			dp += hp->np;
 		}
 		phi = 2.0*PI * (j+.5)/hp->np + PI/2.0;
-		xd += mag * cos(phi);
-		yd += mag * sin(phi);
+		xd += mag * tcos(phi);
+		yd += mag * tsin(phi);
 	}
 	for (i = 0; i < 3; i++)
 		gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])/(hp->nt*hp->np);