57 lines
1.4 KiB
C++
57 lines
1.4 KiB
C++
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#include <cmath>
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#include <algorithm>
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#include <random>
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#include "noise/perlin.hpp"
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PerlinNoise::PerlinNoise() : seed(0) {
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initializeGradients();
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}
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PerlinNoise::PerlinNoise(int seed) : seed(seed) {
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initializeGradients();
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}
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void PerlinNoise::initializeGradients() {
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std::mt19937 gen(seed);
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std::uniform_real_distribution<float> dis(0.0, 2 * M_PI);
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for (int i = 0; i < 256; ++i) {
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float angle = dis(gen);
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grad[i] = Vector2(cos(angle), sin(angle));
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}
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}
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Vector2 PerlinNoise::randoGradient(int ix, int iy) {
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uint32_t hash = ix * 7385451 ^ iy * 19349663;
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return grad[hash & 0xFF];
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}
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float PerlinNoise::dotGridGradient(int ix, int iy, float x, float y) {
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Vector2 gradient = randoGradient(ix, iy);
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Vector2 d(x - (float)ix, y - (float)iy);
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return d.getX() * gradient.getX() + d.getY() * gradient.getY();
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}
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float PerlinNoise::interpolate(float a, float a1, float w) {
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return (a1 - a) * (3.0 - w * 2.0) * w * w + a;
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}
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float PerlinNoise::noise(float x, float y) {
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int x0 = (int)x;
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int y0 = (int)y;
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int x1 = x0 + 1;
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int y1 = y0 + 1;
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Vector2 s(x - (float)x0, y - (float)y0);
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Vector2 n(dotGridGradient(x0, y0, x, y), dotGridGradient(x1, y0, x, y));
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float ix0 = interpolate(n.getX(), n.getY(), s.getX());
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n = Vector2(dotGridGradient(x0, y1, x, y), dotGridGradient(x1, y1, x, y));
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float ix1 = interpolate(n.getX(), n.getY(), s.getX());
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return interpolate(ix0, ix1, s.getY());
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}
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