--- ray/src/rt/noise3.c	1991/05/24 14:23:33	1.5
+++ ray/src/rt/noise3.c	2003/02/25 02:47:22	2.7
@@ -1,20 +1,17 @@
-/* Copyright (c) 1988 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char	RCSid[] = "$Id: noise3.c,v 2.7 2003/02/25 02:47:22 greg Exp $";
 #endif
-
 /*
  *  noise3.c - noise functions for random textures.
  *
  *     Credit for the smooth algorithm goes to Ken Perlin.
  *     (ref. SIGGRAPH Vol 19, No 3, pp 287-96)
- *
- *     4/15/86
- *     5/19/88	Added fractal noise function
  */
 
+#include "copyright.h"
 
+#include  <math.h>
+
 #define  A		0
 #define  B		1
 #define  C		2
@@ -25,21 +22,27 @@ static char SCCSid[] = "$SunId$ LBL";
 #define  rand3c(x,y,z)	frand(89*(x)+97*(y)+101*(z))
 #define  rand3d(x,y,z)	frand(103*(x)+107*(y)+109*(z))
 
-#define  hermite(p0,p1,r0,r1,t)  (	p0*((2.0*t-3.0)*t*t+1.0) + \
-					p1*(-2.0*t+3.0)*t*t + \
-					r0*((t-2.0)*t+1.0)*t + \
-					r1*(t-1.0)*t*t )
+#define  hpoly1(t)	((2.0*t-3.0)*t*t+1.0)
+#define  hpoly2(t)	(-2.0*t+3.0)*t*t
+#define  hpoly3(t)	((t-2.0)*t+1.0)*t
+#define  hpoly4(t)	(t-1.0)*t*t
 
-static char  *noise_name[4] = {"noise3a", "noise3b", "noise3c", "noise3"};
+#define  hermite(p0,p1,r0,r1,t)  (	p0*hpoly1(t) + \
+					p1*hpoly2(t) + \
+					r0*hpoly3(t) + \
+					r1*hpoly4(t) )
+
+static char  noise_name[4][8] = {"noise3x", "noise3y", "noise3z", "noise3"};
 static char  fnoise_name[] = "fnoise3";
 static char  hermite_name[] = "hermite";
 
 double  *noise3(), fnoise3(), argument(), frand();
+static  interpolate();
 
 static long  xlim[3][2];
 static double  xarg[3];
 
-#define  EPSILON	.0001		/* error allowed in fractal */
+#define  EPSILON	.001		/* error allowed in fractal */
 
 #define  frand3(x,y,z)	frand(17*(x)+23*(y)+29*(z))
 
@@ -61,7 +64,8 @@ register char  *nam;
 	while (i--)
 		if (nam == noise_name[i])
 			return(noise3(x)[i]);
-	eputs("Bad call to l_noise3()!\n");
+	eputs(nam);
+	eputs(": called l_noise3!\n");
 	quit(1);
 }
 
@@ -93,7 +97,6 @@ double *
 noise3(xnew)			/* compute the noise function */
 register double  xnew[3];
 {
-	extern double  floor();
 	static double  x[3] = {-100000.0, -100000.0, -100000.0};
 	static double  f[4];
 
@@ -116,7 +119,7 @@ interpolate(f, i, n)
 double  f[4];
 register int  i, n;
 {
-	double  f0[4], f1[4];
+	double  f0[4], f1[4], hp1, hp2;
 
 	if (n == 0) {
 		f[A] = rand3a(xlim[0][i&1],xlim[1][i>>1&1],xlim[2][i>>2]);
@@ -127,10 +130,12 @@ register int  i, n;
 		n--;
 		interpolate(f0, i, n);
 		interpolate(f1, i | 1<<n, n);
-		f[A] = (1.0-xarg[n])*f0[A] + xarg[n]*f1[A];
-		f[B] = (1.0-xarg[n])*f0[B] + xarg[n]*f1[B];
-		f[C] = (1.0-xarg[n])*f0[C] + xarg[n]*f1[C];
-		f[D] = hermite(f0[D], f1[D], f0[n], f1[n], xarg[n]);
+		hp1 = hpoly1(xarg[n]); hp2 = hpoly2(xarg[n]);
+		f[A] = f0[A]*hp1 + f1[A]*hp2;
+		f[B] = f0[B]*hp1 + f1[B]*hp2;
+		f[C] = f0[C]*hp1 + f1[C]*hp2;
+		f[D] = f0[D]*hp1 + f1[D]*hp2 +
+				f0[n]*hpoly3(xarg[n]) + f1[n]*hpoly4(xarg[n]);
 	}
 }
 
@@ -148,7 +153,6 @@ double
 fnoise3(p)			/* compute fractal noise function */
 double  p[3];
 {
-	double  floor();
 	long  t[3], v[3], beg[3];
 	double  fval[8], fc;
 	int  branch;