71 lines
2.6 KiB
C
71 lines
2.6 KiB
C
#include "perlin.h"
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#include "../vec.h"
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static uint32_t seed = 0;
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static const uint8_t hash[] = { 208,34,231,213,32,248,233,56,161,78,24,140,71,48,140,254,245,255,247,247,40,
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185,248,251,245,28,124,204,204,76,36,1,107,28,234,163,202,224,245,128,167,204,
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9,92,217,54,239,174,173,102,193,189,190,121,100,108,167,44,43,77,180,204,8,81,
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70,223,11,38,24,254,210,210,177,32,81,195,243,125,8,169,112,32,97,53,195,13,
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203,9,47,104,125,117,114,124,165,203,181,235,193,206,70,180,174,0,167,181,41,
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164,30,116,127,198,245,146,87,224,149,206,57,4,192,210,65,210,129,240,178,105,
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228,108,245,148,140,40,35,195,38,58,65,207,215,253,65,85,208,76,62,3,237,55,89,
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232,50,217,64,244,157,199,121,252,90,17,212,203,149,152,140,187,234,177,73,174,
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193,100,192,143,97,53,145,135,19,103,13,90,135,151,199,91,239,247,33,39,145,
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101,120,99,3,186,86,99,41,237,203,111,79,220,135,158,42,30,154,120,67,87,167,
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135,176,183,191,253,115,184,21,233,58,129,233,142,39,128,211,118,137,139,255,
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114,20,218,113,154,27,127,246,250,1,8,198,250,209,92,222,173,21,88,102,219 };
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void set_perlin_2d_seed(uint32_t s) {
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seed = s;
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}
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static int32_t noise2(int x, int y)
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{
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int tmp = hash[(y + seed) % 256];
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return hash[(tmp + x) % 256];
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}
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static float lin_inter(float x, float y, float s)
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{
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return x + s * (y-x);
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}
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static float smooth_inter(float x, float y, float s)
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{
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return lin_inter(x, y, s * s * (3-2*s));
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}
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static float noise2d(float x, float y)
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{
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int32_t x_int = (int32_t)x;
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int32_t y_int = (int32_t)y;
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float x_frac = x - (float)x_int;
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float y_frac = y - (float)y_int;
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int32_t s = noise2(x_int, y_int);
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int32_t t = noise2(x_int + 1, y_int);
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int32_t u = noise2(x_int, y_int + 1);
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int v = noise2(x_int + 1, y_int + 1);
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float low = smooth_inter((float)s, (float)t, x_frac);
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float high = smooth_inter((float)u, (float)v, x_frac);
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return smooth_inter(low, high, y_frac);
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}
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/* https://gist.github.com/nowl/828013 */
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float sample_perlin_2d(t_fvec2 position, float frequency, uint8_t octaves) {
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t_fvec2 a = m_vec_scale(position, frequency);
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float amp = 1.0;
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float fin = 0;
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float div = 0.0;
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for(uint8_t i = 0; i < octaves; i++)
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{
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div += 256 * amp;
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fin += noise2d(a.x, a.y) * amp;
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amp /= 2;
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a = m_vec_scale(a, 2);
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}
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return fin/div;
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}
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