From: Perttu Ahola <celeron55@gmail.com>
Date: Sat, 26 Feb 2011 18:16:47 +0000 (+0200)
Subject: 3d noise stuff
X-Git-Url: http://81.2.79.47:8989/gitweb/?a=commitdiff_plain;h=48a772b3c6388cbe7f9003557f27cc2cf51b8fe8;p=zefram%2Fminetest%2Fminetest_engine.git

3d noise stuff
---

diff --git a/src/noise.cpp b/src/noise.cpp
index a98dd588..7b651dbb 100644
--- a/src/noise.cpp
+++ b/src/noise.cpp
@@ -23,6 +23,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #define NOISE_MAGIC_X 1619
 #define NOISE_MAGIC_Y 31337
+#define NOISE_MAGIC_Z 52591
 #define NOISE_MAGIC_SEED 1013
 
 double cos_lookup[16] = {
@@ -50,6 +51,29 @@ double biLinearInterpolation(double x0y0, double x1y0, double x0y1, double x1y1,
     return linearInterpolation(u,v,ty);
 }
 
+double triLinearInterpolation(
+		double v000, double v100, double v010, double v110,
+		double v001, double v101, double v011, double v111,
+		double x, double y, double z)
+{
+    /*double tx = easeCurve(x);
+    double ty = easeCurve(y);
+    double tz = easeCurve(z);*/
+    double tx = x;
+    double ty = y;
+    double tz = z;
+	return(
+		v000*(1-tx)*(1-ty)*(1-tz) +
+		v100*tx*(1-ty)*(1-tz) +
+		v010*(1-tx)*ty*(1-tz) +
+		v110*tx*ty*(1-tz) +
+		v001*(1-tx)*(1-ty)*tz +
+		v101*tx*(1-ty)*tz +
+		v011*(1-tx)*ty*tz +
+		v111*tx*ty*tz
+	);
+}
+
 double noise2d(int x, int y, int seed)
 {
 	int n = (NOISE_MAGIC_X * x + NOISE_MAGIC_Y * y
@@ -59,30 +83,61 @@ double noise2d(int x, int y, int seed)
 	return 1.0 - (double)n/1073741824;
 }
 
+double noise3d(int x, int y, int z, int seed)
+{
+	int n = (NOISE_MAGIC_X * x + NOISE_MAGIC_Y * y + NOISE_MAGIC_Z * z
+			+ 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)
 {
+	// Calculate the integer coordinates
 	int x0 = (x > 0.0 ? (int)x : (int)x - 1);
 	int y0 = (y > 0.0 ? (int)y : (int)y - 1);
+	// Calculate the remaining part of the coordinates
 	double xl = x - (double)x0;
 	double yl = y - (double)y0;
+	// Calculate random cosine lookup table indices for the integer corners.
+	// They are looked up as unit vector gradients from the lookup table.
 	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);
-	/* In this format, these fail to work on MSVC8 if n00 < 4
-	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);*/
+	// Make a dot product for the gradients and the positions, to get the values
 	double s = dotProduct(cos_lookup[n00], cos_lookup[(n00+12)%16], xl, yl);
 	double u = dotProduct(-cos_lookup[n10], cos_lookup[(n10+12)%16], 1.-xl, yl);
 	double v = dotProduct(cos_lookup[n01], -cos_lookup[(n01+12)%16], xl, 1.-yl);
 	double w = dotProduct(-cos_lookup[n11], -cos_lookup[(n11+12)%16], 1.-xl, 1.-yl);
-	/*std::cout<<"x="<<x<<" y="<<y<<" x0="<<x0<<" y0="<<y0<<" xl="<<xl<<" yl="<<yl<<" n00="<<n00<<" n10="<<n01<<" s="<<s<<std::endl;
-	std::cout<<"cos_lookup[n00]="<<(cos_lookup[n00])<<" cos_lookup[(n00-4)%16]="<<(cos_lookup[(n00-4)%16])<<std::endl;*/
+	// Interpolate between the values
 	return biLinearInterpolation(s,u,v,w,xl,yl);
 }
 
+double noise3d_gradient(double x, double y, double z, int seed)
+{
+	// Calculate the integer coordinates
+	int x0 = (x > 0.0 ? (int)x : (int)x - 1);
+	int y0 = (y > 0.0 ? (int)y : (int)y - 1);
+	int z0 = (z > 0.0 ? (int)z : (int)z - 1);
+	// Calculate the remaining part of the coordinates
+	double xl = x - (double)x0;
+	double yl = y - (double)y0;
+	double zl = y - (double)z0;
+	// Get values for corners of cube
+	double v000 = noise3d(x0, y0, z0, seed);
+	double v100 = noise3d(x0+1, y0, z0, seed);
+	double v010 = noise3d(x0, y0+1, z0, seed);
+	double v110 = noise3d(x0+1, y0+1, z0, seed);
+	double v001 = noise3d(x0, y0, z0+1, seed);
+	double v101 = noise3d(x0+1, y0, z0+1, seed);
+	double v011 = noise3d(x0, y0+1, z0+1, seed);
+	double v111 = noise3d(x0+1, y0+1, z0+1, seed);
+	// Interpolate
+	return triLinearInterpolation(v000,v100,v010,v110,v001,v101,v011,v111,xl,yl,zl);
+}
+
 double noise2d_perlin(double x, double y, int seed,
 		int octaves, double persistence)
 {
@@ -98,3 +153,18 @@ double noise2d_perlin(double x, double y, int seed,
 	return a;
 }
 
+double noise3d_perlin(double x, double y, double z, 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 * noise3d_gradient(x*f, y*f, z*f, seed+i);
+		f *= 2.0;
+		g *= persistence;
+	}
+	return a;
+}
+
diff --git a/src/noise.h b/src/noise.h
index c069046c..63974e86 100644
--- a/src/noise.h
+++ b/src/noise.h
@@ -24,11 +24,16 @@ double easeCurve(double t);
  
 // Return value: -1 ... 1
 double noise2d(int x, int y, int seed);
+double noise3d(int x, int y, int z, int seed);
 
 double noise2d_gradient(double x, double y, int seed);
+double noise3d_gradient(double x, double y, double z, int seed);
 
 double noise2d_perlin(double x, double y, int seed,
 		int octaves, double persistence);
 
+double noise3d_perlin(double x, double y, double z, int seed,
+		int octaves, double persistence);
+
 #endif