--- ray/src/rt/ambcomp.c	1998/12/16 18:14:57	2.8
+++ ray/src/rt/ambcomp.c	2005/04/13 23:00:59	2.13
@@ -1,33 +1,21 @@
-/* Copyright (c) 1998 Silicon Graphics, Inc. */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ SGI";
+static const char	RCSid[] = "$Id: ambcomp.c,v 2.13 2005/04/13 23:00:59 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 */
-
-
 static int
 ambcmp(d1, d2)				/* decreasing order */
 AMBSAMP  *d1, *d2;
@@ -46,12 +34,13 @@ AMBSAMP  *d1, *d2;
 {
 	register int  c;
 
-	if (c = d1->t - d2->t)
+	if ( (c = d1->t - d2->t) )
 		return(c);
 	return(d1->p - d2->p);
 }
 
 
+int
 divsample(dp, h, r)			/* sample a division */
 register AMBSAMP  *dp;
 AMBHEMI  *h;
@@ -84,9 +73,9 @@ RAY  *r;
 	rayvalue(&ar);
 	ndims--;
 	addcolor(dp->v, ar.rcol);
-					/* be conservative and use rot */
-	if (ar.rot > FTINY && ar.rot < FHUGE)
-		dp->r += 1.0/ar.rot;
+					/* use rt to improve gradient calc */
+	if (ar.rt > FTINY && ar.rt < FHUGE)
+		dp->r += 1.0/ar.rt;
 					/* (re)initialize error */
 	if (dp->n++) {
 		b2 = bright(dp->v)/dp->n - bright(ar.rcol);
@@ -153,17 +142,17 @@ FVECT  pg, dg;
 		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);
@@ -202,7 +191,7 @@ 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);
@@ -228,11 +217,12 @@ FVECT  pg, dg;
 	return(arad);
 oopsy:
 	if (div != NULL)
-		free((char *)div);
+		free((void *)div);
 	return(0.0);
 }
 
 
+void
 inithemi(hp, r, wt)		/* initialize sampling hemisphere */
 register AMBHEMI  *hp;
 RAY  *r;
@@ -240,11 +230,10 @@ double  wt;
 {
 	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;
+	i = ambacc > FTINY ? 3 : 1;	/* minimum number of samples */
+	if (hp->nt < i)
+		hp->nt = i;
 	hp->np = PI * hp->nt + 0.5;
 					/* make axes */
 	VCOPY(hp->uz, r->ron);
@@ -261,6 +250,7 @@ double  wt;
 }
 
 
+void
 comperrs(da, hp)		/* compute initial error estimates */
 AMBSAMP  *da;		/* assumes standard ordering */
 register AMBHEMI  *hp;
@@ -311,6 +301,7 @@ register AMBHEMI  *hp;
 }
 
 
+void
 posgradient(gv, da, hp)				/* compute position gradient */
 FVECT  gv;
 AMBSAMP  *da;			/* assumes standard ordering */
@@ -367,6 +358,7 @@ register AMBHEMI  *hp;
 }
 
 
+void
 dirgradient(gv, da, hp)				/* compute direction gradient */
 FVECT  gv;
 AMBSAMP  *da;			/* assumes standard ordering */