112 lines
3.1 KiB
C++
112 lines
3.1 KiB
C++
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#include "PerlinNoise.h"
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PerlinNoise::PerlinNoise()
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{
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persistence = 0;
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frequency = 0;
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amplitude = 0;
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octaves = 0;
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randomseed = 0;
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}
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PerlinNoise::PerlinNoise(double _persistence, double _frequency, double _amplitude, int _octaves, int _randomseed)
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{
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persistence = _persistence;
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frequency = _frequency;
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amplitude = _amplitude;
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octaves = _octaves;
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randomseed = 2 + _randomseed * _randomseed;
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}
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void PerlinNoise::Set(double _persistence, double _frequency, double _amplitude, int _octaves, int _randomseed)
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{
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persistence = _persistence;
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frequency = _frequency;
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amplitude = _amplitude;
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octaves = _octaves;
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randomseed = 2 + _randomseed * _randomseed;
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}
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double PerlinNoise::GetHeight(double x, double y) const
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{
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return amplitude * Total(x, y);
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}
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double PerlinNoise::Total(double i, double j) const
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{
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//properties of one octave (changing each loop)
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double t = 0.0f;
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double _amplitude = 1;
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double freq = frequency;
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for(int k = 0; k < octaves; k++)
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{
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t += GetValue(j * freq + randomseed, i * freq + randomseed) * _amplitude;
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_amplitude *= persistence;
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freq *= 2;
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}
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return t;
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}
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double PerlinNoise::GetValue(double x, double y) const
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{
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int Xint = (int)x;
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int Yint = (int)y;
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double Xfrac = x - Xint;
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double Yfrac = y - Yint;
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//noise values
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double n01 = Noise(Xint-1, Yint-1);
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double n02 = Noise(Xint+1, Yint-1);
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double n03 = Noise(Xint-1, Yint+1);
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double n04 = Noise(Xint+1, Yint+1);
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double n05 = Noise(Xint-1, Yint);
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double n06 = Noise(Xint+1, Yint);
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double n07 = Noise(Xint, Yint-1);
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double n08 = Noise(Xint, Yint+1);
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double n09 = Noise(Xint, Yint);
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double n12 = Noise(Xint+2, Yint-1);
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double n14 = Noise(Xint+2, Yint+1);
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double n16 = Noise(Xint+2, Yint);
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double n23 = Noise(Xint-1, Yint+2);
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double n24 = Noise(Xint+1, Yint+2);
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double n28 = Noise(Xint, Yint+2);
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double n34 = Noise(Xint+2, Yint+2);
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//find the noise values of the four corners
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double x0y0 = 0.0625*(n01+n02+n03+n04) + 0.125*(n05+n06+n07+n08) + 0.25*(n09);
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double x1y0 = 0.0625*(n07+n12+n08+n14) + 0.125*(n09+n16+n02+n04) + 0.25*(n06);
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double x0y1 = 0.0625*(n05+n06+n23+n24) + 0.125*(n03+n04+n09+n28) + 0.25*(n08);
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double x1y1 = 0.0625*(n09+n16+n28+n34) + 0.125*(n08+n14+n06+n24) + 0.25*(n04);
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//interpolate between those values according to the x and y fractions
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double v1 = Interpolate(x0y0, x1y0, Xfrac); //interpolate in x direction (y)
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double v2 = Interpolate(x0y1, x1y1, Xfrac); //interpolate in x direction (y+1)
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double fin = Interpolate(v1, v2, Yfrac); //interpolate in y direction
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return fin;
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}
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double PerlinNoise::Interpolate(double x, double y, double a) const
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{
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double negA = 1.0 - a;
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double negASqr = negA * negA;
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double fac1 = 3.0 * (negASqr) - 2.0 * (negASqr * negA);
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double aSqr = a * a;
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double fac2 = 3.0 * aSqr - 2.0 * (aSqr * a);
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return x * fac1 + y * fac2; //add the weighted factors
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}
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double PerlinNoise::Noise(int x, int y) const
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{
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int n = x + y * 57;
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n = (n << 13) ^ n;
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int t = (n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff;
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return 1.0 - double(t) * 0.931322574615478515625e-9;/// 1073741824.0);
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}
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