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https://github.com/moparisthebest/minetest
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3d noise stuff
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@ -23,6 +23,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
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#define NOISE_MAGIC_X 1619
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#define NOISE_MAGIC_Y 31337
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#define NOISE_MAGIC_Z 52591
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#define NOISE_MAGIC_SEED 1013
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double cos_lookup[16] = {
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@ -50,6 +51,29 @@ double biLinearInterpolation(double x0y0, double x1y0, double x0y1, double x1y1,
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return linearInterpolation(u,v,ty);
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}
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double triLinearInterpolation(
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double v000, double v100, double v010, double v110,
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double v001, double v101, double v011, double v111,
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double x, double y, double z)
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{
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/*double tx = easeCurve(x);
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double ty = easeCurve(y);
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double tz = easeCurve(z);*/
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double tx = x;
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double ty = y;
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double tz = z;
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return(
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v000*(1-tx)*(1-ty)*(1-tz) +
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v100*tx*(1-ty)*(1-tz) +
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v010*(1-tx)*ty*(1-tz) +
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v110*tx*ty*(1-tz) +
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v001*(1-tx)*(1-ty)*tz +
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v101*tx*(1-ty)*tz +
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v011*(1-tx)*ty*tz +
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v111*tx*ty*tz
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);
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}
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double noise2d(int x, int y, int seed)
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{
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int n = (NOISE_MAGIC_X * x + NOISE_MAGIC_Y * y
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@ -59,30 +83,61 @@ double noise2d(int x, int y, int seed)
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return 1.0 - (double)n/1073741824;
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}
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double noise3d(int x, int y, int z, int seed)
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{
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int n = (NOISE_MAGIC_X * x + NOISE_MAGIC_Y * y + NOISE_MAGIC_Z * z
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+ NOISE_MAGIC_SEED * seed) & 0x7fffffff;
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n = (n>>13)^n;
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n = (n * (n*n*60493+19990303) + 1376312589) & 0x7fffffff;
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return 1.0 - (double)n/1073741824;
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}
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double noise2d_gradient(double x, double y, int seed)
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{
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// Calculate the integer coordinates
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int x0 = (x > 0.0 ? (int)x : (int)x - 1);
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int y0 = (y > 0.0 ? (int)y : (int)y - 1);
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// Calculate the remaining part of the coordinates
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double xl = x - (double)x0;
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double yl = y - (double)y0;
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// Calculate random cosine lookup table indices for the integer corners.
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// They are looked up as unit vector gradients from the lookup table.
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int n00 = (int)((noise2d(x0, y0, seed)+1)*8);
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int n10 = (int)((noise2d(x0+1, y0, seed)+1)*8);
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int n01 = (int)((noise2d(x0, y0+1, seed)+1)*8);
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int n11 = (int)((noise2d(x0+1, y0+1, seed)+1)*8);
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/* In this format, these fail to work on MSVC8 if n00 < 4
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double s = dotProduct(cos_lookup[n00], cos_lookup[(n00-4)%16], xl, yl);
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double u = dotProduct(-cos_lookup[n10], cos_lookup[(n10-4)%16], 1.-xl, yl);
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double v = dotProduct(cos_lookup[n01], -cos_lookup[(n01-4)%16], xl, 1.-yl);
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double w = dotProduct(-cos_lookup[n11], -cos_lookup[(n11-4)%16], 1.-xl, 1.-yl);*/
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// Make a dot product for the gradients and the positions, to get the values
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double s = dotProduct(cos_lookup[n00], cos_lookup[(n00+12)%16], xl, yl);
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double u = dotProduct(-cos_lookup[n10], cos_lookup[(n10+12)%16], 1.-xl, yl);
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double v = dotProduct(cos_lookup[n01], -cos_lookup[(n01+12)%16], xl, 1.-yl);
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double w = dotProduct(-cos_lookup[n11], -cos_lookup[(n11+12)%16], 1.-xl, 1.-yl);
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/*std::cout<<"x="<<x<<" y="<<y<<" x0="<<x0<<" y0="<<y0<<" xl="<<xl<<" yl="<<yl<<" n00="<<n00<<" n10="<<n01<<" s="<<s<<std::endl;
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std::cout<<"cos_lookup[n00]="<<(cos_lookup[n00])<<" cos_lookup[(n00-4)%16]="<<(cos_lookup[(n00-4)%16])<<std::endl;*/
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// Interpolate between the values
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return biLinearInterpolation(s,u,v,w,xl,yl);
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}
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double noise3d_gradient(double x, double y, double z, int seed)
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{
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// Calculate the integer coordinates
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int x0 = (x > 0.0 ? (int)x : (int)x - 1);
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int y0 = (y > 0.0 ? (int)y : (int)y - 1);
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int z0 = (z > 0.0 ? (int)z : (int)z - 1);
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// Calculate the remaining part of the coordinates
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double xl = x - (double)x0;
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double yl = y - (double)y0;
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double zl = y - (double)z0;
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// Get values for corners of cube
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double v000 = noise3d(x0, y0, z0, seed);
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double v100 = noise3d(x0+1, y0, z0, seed);
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double v010 = noise3d(x0, y0+1, z0, seed);
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double v110 = noise3d(x0+1, y0+1, z0, seed);
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double v001 = noise3d(x0, y0, z0+1, seed);
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double v101 = noise3d(x0+1, y0, z0+1, seed);
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double v011 = noise3d(x0, y0+1, z0+1, seed);
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double v111 = noise3d(x0+1, y0+1, z0+1, seed);
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// Interpolate
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return triLinearInterpolation(v000,v100,v010,v110,v001,v101,v011,v111,xl,yl,zl);
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}
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double noise2d_perlin(double x, double y, int seed,
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int octaves, double persistence)
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{
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@ -98,3 +153,18 @@ double noise2d_perlin(double x, double y, int seed,
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return a;
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}
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double noise3d_perlin(double x, double y, double z, int seed,
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int octaves, double persistence)
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{
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double a = 0;
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double f = 1.0;
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double g = 1.0;
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for(int i=0; i<octaves; i++)
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{
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a += g * noise3d_gradient(x*f, y*f, z*f, seed+i);
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f *= 2.0;
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g *= persistence;
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}
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return a;
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}
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@ -24,11 +24,16 @@ double easeCurve(double t);
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// Return value: -1 ... 1
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double noise2d(int x, int y, int seed);
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double noise3d(int x, int y, int z, int seed);
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double noise2d_gradient(double x, double y, int seed);
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double noise3d_gradient(double x, double y, double z, int seed);
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double noise2d_perlin(double x, double y, int seed,
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int octaves, double persistence);
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double noise3d_perlin(double x, double y, double z, int seed,
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int octaves, double persistence);
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#endif
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