Generation of perlin noise structures
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PerlinNoise.cpp
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123
PerlinNoise.cpp
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#include "PerlinNoise.hpp"
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Point vector_product(Point u, Point v) {
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Point u_v(0,0,0);
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u_v.x = u.y* v.z - u.z * v.y;
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u_v.y = u.z* v.x - u.x * v.z;
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u_v.z = u.x* v.y - u.y * v.x;
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return u_v;
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}
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PerlinNoise::PerlinNoise() : ImplicitSurface(Point(0,0,0)) {
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// permutation vector (source : http://mrl.nyu.edu/~perlin/noise/)
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p = {
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151,160,137,91,90,15,131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,
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8,99,37,240,21,10,23,190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,
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35,11,32,57,177,33,88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,
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134,139,48,27,166,77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,
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55,46,245,40,244,102,143,54, 65,25,63,161,1,216,80,73,209,76,132,187,208, 89,
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18,169,200,196,135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,
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250,124,123,5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,
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189,28,42,223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167,
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43,172,9,129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,
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97,228,251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,
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107,49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,
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138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180 };
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// Duplication of the permutation vector.
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p.insert(p.end(), p.begin(), p.end());
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}
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PerlinNoise::PerlinNoise(unsigned int seed) : ImplicitSurface(Point(0,0,0)) {
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p.resize(256);
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// Fill p with values from 0 to 255
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std::iota(p.begin(), p.end(), 0);
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// Initialize a random engine with seed
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std::default_random_engine engine(seed);
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// Shuffle using the above random engine
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std::shuffle(p.begin(), p.end(), engine);
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// Duplicate the permutation vector
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p.insert(p.end(), p.begin(), p.end());
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}
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double PerlinNoise::operator() (double x, double y, double z) const {
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return z - noise(x, y, 0);
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}
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double PerlinNoise::noise(double _x, double _y, double _z) const {
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int X = (int) floor(_x) & 255;
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int Y = (int) floor(_y) & 255;
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int Z = (int) floor(_z) & 255;
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_x -= floor(_x);
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_y -= floor(_y);
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_z -= floor(_z);
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double u = fade(_x);
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double v = fade(_y);
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double w = fade(_z);
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int A = p[X] + Y;
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int AA = p[A] + Z;
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int AB = p[A + 1] + Z;
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int B = p[X + 1] + Y;
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int BA = p[B] + Z;
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int BB = p[B + 1] + Z;
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double res = lerp(
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w,
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lerp(
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v,
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lerp(u, grad(p[AA], _x, _y, _z), grad(p[BA], _x-1, _y, _z)),
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lerp(u, grad(p[AB], _x, _y-1, _z), grad(p[BB], _x-1, _y-1, _z))
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),
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lerp(
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v,
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lerp(
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u,
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grad(p[AA+1], _x, _y, _z-1),
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grad(p[BA+1], _x-1, _y, _z-1)
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),
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lerp(
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u,
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grad(p[AB+1], _x, _y-1, _z-1),
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grad(p[BB+1], _x-1, _y-1, _z-1)
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)
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)
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);
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return (res + 1.0)/2.0;
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}
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double PerlinNoise::noise(double _x, double _y) const {
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return noise(_x, _y, 0);
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}
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double PerlinNoise::fade(double t) const {
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return t * t * t * (t * (t * 6 - 15) + 10);
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}
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double PerlinNoise::lerp(double t, double a, double b) const {
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return a + t * (b-a);
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}
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double PerlinNoise::grad(int hash, double x, double y, double z) const {
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int h = hash & 15;
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// Convert lower 4 bits of hash into 12 gradient directions
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double u = h < 8 ? x : y,
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v = h < 4 ? y : h == 12 || h == 14 ? x : z;
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return ((h & 1) == 0 ? u : -u) + ((h & 2) == 0 ? v : -v);
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}
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Point PerlinNoise::normal_vector(double x, double y) {
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double n_x_y = noise(x, y, 0);
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double n_dx_y = noise(x + 0.01, y, 0);
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double n_x_dy = noise(x, y + 0.01, 0);
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Point product = vector_product(
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Point(0.01, 0, n_dx_y - n_x_y),
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Point(0, 0.01, (n_x_dy - n_x_y))
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);
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return product;
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}
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23
PerlinNoise.hpp
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23
PerlinNoise.hpp
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@ -0,0 +1,23 @@
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/**
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* Perlin Noise implementation for the ground (header file)
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**/
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#include "Implicit.hpp"
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#include <cmath>
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#include <random>
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#include <vector>
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#include <algorithm>
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class PerlinNoise : public ImplicitSurface {
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std::vector<int> p;
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public:
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PerlinNoise();
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PerlinNoise(unsigned int seed);
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double operator() (double _x, double _y, double _z) const;
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double noise(double x, double y) const;
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Point normal_vector(double x, double y);
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private:
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double noise(double x, double y, double z) const;
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double fade(double t) const;
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double lerp(double t, double a, double b) const;
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double grad(int hash, double x, double y, double z) const;
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};
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