--- ray/src/rt/noise3.c	1989/03/03 12:25:34	1.2
+++ ray/src/rt/noise3.c	1991/10/10 16:43:40	1.7
@@ -25,78 +25,76 @@ 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
 
-double  *noise3(), noise3coef(), argument(), frand();
+#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] = {"noise3a", "noise3b", "noise3c", "noise3"};
+static char  fnoise_name[] = "fnoise3";
+static char  hermite_name[] = "hermite";
+
+double  *noise3(), fnoise3(), argument(), frand();
+
 static long  xlim[3][2];
 static double  xarg[3];
 
 #define  EPSILON	.0001		/* error allowed in fractal */
 
-#define  frand3(x,y,z)	frand((long)((12.38*(x)-22.30*(y)-42.63*(z))/EPSILON))
+#define  frand3(x,y,z)	frand(17*(x)+23*(y)+29*(z))
 
-double  fnoise3();
 
-
-double
-l_noise3()			/* compute 3-dimensional noise function */
+static double
+l_noise3(nam)			/* compute a noise function */
+register char  *nam;
 {
-	return(noise3coef(D));
+	register int  i;
+	double  x[3];
+					/* get point */
+	x[0] = argument(1);
+	x[1] = argument(2);
+	x[2] = argument(3);
+					/* make appropriate call */
+	if (nam == fnoise_name)
+		return(fnoise3(x));
+	i = 4;
+	while (i--)
+		if (nam == noise_name[i])
+			return(noise3(x)[i]);
+	eputs(nam);
+	eputs(": called l_noise3!\n");
+	quit(1);
 }
 
 
 double
-l_noise3a()			/* compute x slope of noise function */
+l_hermite()			/* library call for hermite interpolation */
 {
-	return(noise3coef(A));
+	double  t;
+	
+	t = argument(5);
+	return( hermite(argument(1), argument(2),
+			argument(3), argument(4), t) );
 }
 
 
-double
-l_noise3b()			/* compute y slope of noise function */
+setnoisefuncs()			/* add noise functions to library */
 {
-	return(noise3coef(B));
-}
+	register int  i;
 
-
-double
-l_noise3c()			/* compute z slope of noise function */
-{
-	return(noise3coef(C));
+	funset(hermite_name, 5, ':', l_hermite);
+	funset(fnoise_name, 3, ':', l_noise3);
+	i = 4;
+	while (i--)
+		funset(noise_name[i], 3, ':', l_noise3);
 }
 
 
-double
-l_fnoise3()			/* compute fractal noise function */
-{
-	double  x[3];
-
-	x[0] = argument(1);
-	x[1] = argument(2);
-	x[2] = argument(3);
-
-	return(fnoise3(x));
-}
-
-
-static double
-noise3coef(coef)		/* return coefficient of noise function */
-int  coef;
-{
-	double  x[3];
-
-	x[0] = argument(1);
-	x[1] = argument(2);
-	x[2] = argument(3);
-
-	return(noise3(x)[coef]);
-}
-
-
 double *
 noise3(xnew)			/* compute the noise function */
 register double  xnew[3];
@@ -124,7 +122,7 @@ 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]);
@@ -135,10 +133,12 @@ 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]);
 	}
 }
 
@@ -153,56 +153,45 @@ register long  s;
 
 
 double
-l_hermite()			/* library call for hermite interpolation */
-{
-	double  t;
-	
-	t = argument(5);
-	return( hermite(argument(1), argument(2),
-			argument(3), argument(4), t) );
-}
-
-
-double
 fnoise3(p)			/* compute fractal noise function */
-register double  p[3];
+double  p[3];
 {
 	double  floor();
-	double  v[3], beg[3], fval[8], s, fc;
-	int  closing, branch;
+	long  t[3], v[3], beg[3];
+	double  fval[8], fc;
+	int  branch;
+	register long  s;
 	register int  i, j;
 						/* get starting cube */
-	for (i = 0; i < 3; i++)
-		beg[i] = floor(p[i]);
+	s = (long)(1.0/EPSILON);
+	for (i = 0; i < 3; i++) {
+		t[i] = s*p[i];
+		beg[i] = s*floor(p[i]);
+	}
 	for (j = 0; j < 8; j++) {
 		for (i = 0; i < 3; i++) {
 			v[i] = beg[i];
 			if (j & 1<<i)
-				v[i] += 1.0;
+				v[i] += s;
 		}
 		fval[j] = frand3(v[0],v[1],v[2]);
 	}
-	s = 1.0;
 						/* compute fractal */
 	for ( ; ; ) {
-		s *= 0.5;
+		fc = 0.0;
+		for (j = 0; j < 8; j++)
+			fc += fval[j];
+		fc *= 0.125;
+		if ((s >>= 1) == 0)
+			return(fc);		/* close enough */
 		branch = 0;
-		closing = 0;
 		for (i = 0; i < 3; i++) {	/* do center */
 			v[i] = beg[i] + s;
-			if (p[i] > v[i]) {
+			if (t[i] > v[i]) {
 				branch |= 1<<i;
-				if (p[i] - v[i] > EPSILON)
-					closing++;
-			} else if (v[i] - p[i] > EPSILON)
-				closing++;
+			}
 		}
-		fc = 0.0;
-		for (j = 0; j < 8; j++)
-			fc += fval[j];
-		fc = 0.125*fc + s*frand3(v[0],v[1],v[2]);
-		if (closing == 0)
-			return(fc);		/* close enough */
+		fc += s*EPSILON*frand3(v[0],v[1],v[2]);
 		fval[~branch & 7] = fc;
 		for (i = 0; i < 3; i++) {	/* do faces */
 			if (branch & 1<<i)
@@ -213,7 +202,7 @@ register double  p[3];
 			for (j = 0; j < 8; j++)
 				if (~(j^branch) & 1<<i)
 					fc += fval[j];
-			fc = 0.25*fc + s*frand3(v[0],v[1],v[2]);
+			fc = 0.25*fc + s*EPSILON*frand3(v[0],v[1],v[2]);
 			fval[~(branch^1<<i) & 7] = fc;
 			v[i] = beg[i] + s;
 		}
@@ -230,7 +219,7 @@ register double  p[3];
 				v[j] -= s;
 			fc = fval[branch & ~(1<<i)];
 			fc += fval[branch | 1<<i];
-			fc = 0.5*fc + s*frand3(v[0],v[1],v[2]);
+			fc = 0.5*fc + s*EPSILON*frand3(v[0],v[1],v[2]);
 			fval[branch^1<<i] = fc;
 			j = (i+1)%3;
 			v[j] = beg[j] + s;