mpri-graphics-project/PerlinNoise.cpp

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#include "PerlinNoise.hpp"
Point vector_product(Point u, Point v) {
Point u_v(0,0,0);
u_v.x = u.y* v.z - u.z * v.y;
u_v.y = u.z* v.x - u.x * v.z;
u_v.z = u.x* v.y - u.y * v.x;
return u_v;
}
PerlinNoise::PerlinNoise() : ImplicitSurface(Point(0,0,0)) {
// permutation vector (source : http://mrl.nyu.edu/~perlin/noise/)
p = {
151,160,137,91,90,15,131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,
8,99,37,240,21,10,23,190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,
35,11,32,57,177,33,88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,
134,139,48,27,166,77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,
55,46,245,40,244,102,143,54, 65,25,63,161,1,216,80,73,209,76,132,187,208, 89,
18,169,200,196,135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,
250,124,123,5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,
189,28,42,223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167,
43,172,9,129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,
97,228,251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,
107,49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,
138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180 };
// Duplication of the permutation vector.
p.insert(p.end(), p.begin(), p.end());
}
PerlinNoise::PerlinNoise(unsigned int seed) : ImplicitSurface(Point(0,0,0)) {
p.resize(256);
// Fill p with values from 0 to 255
std::iota(p.begin(), p.end(), 0);
// Initialize a random engine with seed
std::default_random_engine engine(seed);
// Shuffle using the above random engine
std::shuffle(p.begin(), p.end(), engine);
// Duplicate the permutation vector
p.insert(p.end(), p.begin(), p.end());
}
double PerlinNoise::operator() (double x, double y, double z) const {
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return z - fBm(x, 0, y, 2, 0.3, 2.0);
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}
double PerlinNoise::noise(double _x, double _y, double _z) const {
int X = (int) floor(_x) & 255;
int Y = (int) floor(_y) & 255;
int Z = (int) floor(_z) & 255;
_x -= floor(_x);
_y -= floor(_y);
_z -= floor(_z);
double u = fade(_x);
double v = fade(_y);
double w = fade(_z);
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int A = p[X] + Z;
int AA = p[A] + Y;
int AB = p[A + 1] + Y;
int B = p[X + 1] + Z;
int BA = p[B] + Y;
int BB = p[B + 1] + Y;
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double res = lerp(
w,
lerp(
v,
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lerp(u, grad(p[AA], _x, _z, _y), grad(p[BA], _x-1, _z, _y)),
lerp(u, grad(p[AB], _x, _z-1, _y), grad(p[BB], _x-1, _z-1, _y))
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),
lerp(
v,
lerp(
u,
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grad(p[AA+1], _x, _z, _y-1),
grad(p[BA+1], _x-1, _z, _y-1)
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),
lerp(
u,
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grad(p[AB+1], _x, _z-1, _y-1),
grad(p[BB+1], _x-1, _z-1, _y-1)
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)
)
);
return (res + 1.0)/2.0;
}
double PerlinNoise::noise(double _x, double _y) const {
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return noise(_x, 0, _y);
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}
double PerlinNoise::fade(double t) const {
return t * t * t * (t * (t * 6 - 15) + 10);
}
double PerlinNoise::lerp(double t, double a, double b) const {
return a + t * (b-a);
}
double PerlinNoise::grad(int hash, double x, double y, double z) const {
int h = hash & 15;
// Convert lower 4 bits of hash into 12 gradient directions
double u = h < 8 ? x : y,
v = h < 4 ? y : h == 12 || h == 14 ? x : z;
return ((h & 1) == 0 ? u : -u) + ((h & 2) == 0 ? v : -v);
}
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double PerlinNoise::fBm(double x, double y, double z, int octaves, double
lacunarity, double gain) const {
double amplitude = 1.0;
double frequency = 1.0;
double sum = 0.0;
for(int i = 0; i < octaves; ++i)
{
// sum += amplitude * (1-abs(noise(x * frequency, y * frequency, z * frequency)));
sum += amplitude * noise(x * frequency, y * frequency, z * frequency);
amplitude *= gain;
frequency *= lacunarity;
}
return sum;
}
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Point PerlinNoise::normal_vector(double x, double y) {
double n_x_y = noise(x, y, 0);
double n_dx_y = noise(x + 0.01, y, 0);
double n_x_dy = noise(x, y + 0.01, 0);
Point product = vector_product(
Point(0.01, 0, n_dx_y - n_x_y),
Point(0, 0.01, (n_x_dy - n_x_y))
);
return product;
}
Point PerlinNoise::location_hint() const {
return location_hint(0, 0);
}
Point PerlinNoise::location_hint(double x, double z) const {
return Point(x, noise(x, z), z);
}