added noise.*

src/noise.cpp

+/*
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include <math.h>
+#include "noise.h"
+
+#define NOISE_MAGIC_X 1619
+#define NOISE_MAGIC_Y 31337
+#define NOISE_MAGIC_SEED 1013
+
+double cos_lookup[16] = {
+	1.0,0.9238,0.7071,0.3826,0,-0.3826,-0.7071,-0.9238,
+	1.0,-0.9238,-0.7071,-0.3826,0,0.3826,0.7071,0.9238
+};
+
+double dotProduct(double vx, double vy, double wx, double wy){
+    return vx*wx+vy*wy;
+}
+ 
+double easeCurve(double t){
+    return 6*pow(t,5)-15*pow(t,4)+10*pow(t,3);
+}
+ 
+double linearInterpolation(double x0, double x1, double t){
+    return x0+(x1-x0)*t;
+}
+ 
+double biLinearInterpolation(double x0y0, double x1y0, double x0y1, double x1y1, double x, double y){
+    double tx = easeCurve(x);
+    double ty = easeCurve(y);
+    double u = linearInterpolation(x0y0,x1y0,tx);
+    double v = linearInterpolation(x0y1,x1y1,tx);
+    return linearInterpolation(u,v,ty);
+}
+
+double noise2d(int x, int y, int seed)
+{
+	int n = (NOISE_MAGIC_X * x + NOISE_MAGIC_Y * y
+			+ NOISE_MAGIC_SEED * seed) & 0x7fffffff;
+	n = (n>>13)^n;
+	n = (n * (n*n*60493+19990303) + 1376312589) & 0x7fffffff;
+	return 1.0 - (double)n/1073741824;
+}
+
+double noise2d_gradient(double x, double y, int seed)
+{
+	int x0 = (x > 0.0 ? (int)x : (int)x - 1);
+	int y0 = (y > 0.0 ? (int)y : (int)y - 1);
+	double xl = x-x0;
+	double yl = y-y0;
+	int n00 = (int)((noise2d(x0, y0, seed)+1)*8);
+	int n10 = (int)((noise2d(x0+1, y0, seed)+1)*8);
+	int n01 = (int)((noise2d(x0, y0+1, seed)+1)*8);
+	int n11 = (int)((noise2d(x0+1, y0+1, seed)+1)*8);
+	double s = dotProduct(cos_lookup[n00], cos_lookup[(n00-4)%16], xl, yl);
+	double u = dotProduct(-cos_lookup[n10], cos_lookup[(n10-4)%16], 1.-xl, yl);
+	double v = dotProduct(cos_lookup[n01], -cos_lookup[(n01-4)%16], xl, 1.-yl);
+	double w = dotProduct(-cos_lookup[n11], -cos_lookup[(n11-4)%16], 1.-xl, 1.-yl);
+	return biLinearInterpolation(s,u,v,w,xl,yl);
+}
+
+double noise2d_perlin(double x, double y, int seed,
+		int octaves, double persistence)
+{
+	double a = 0;
+	double f = 1.0;
+	double g = 1.0;
+	for(int i=0; i<octaves; i++)
+	{
+		a += g * noise2d_gradient(x*f, y*f, seed+i);
+		f *= 2.0;
+		g *= persistence;
+	}
+	return a;
+}
+

src/noise.h

+/*
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef NOISE_HEADER
+#define NOISE_HEADER
+
+// Return value: -1 ... 1
+double noise2d(int x, int y, int seed);
+
+double noise2d_gradient(double x, double y, int seed);
+
+double noise2d_perlin(double x, double y, int seed,
+		int octaves, double persistence);
+
+#endif
+