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perlin.c
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perlin.c
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#include "perlin.h"
#include <math.h>
static int perm[256] = {
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
};
static inline float perm_ref(int index) {
return perm[index & 0xff];
}
static inline float fade(float t) {
return t * t * t * (t * (t * 6.0f - 15.0f) + 10.0f);
}
static inline float lerp(float t, float a, float b) {
return a + t * (b - a);
}
static inline float grad3d(int hash, float x, float y, float z) {
int h = hash & 0xf;
float u = h < 8 ? x : y;
float v = h < 4 ? y : (h == 12 || h == 14 ? x : z);
return ((h & 1) ? u : -u) + ((h & 2) ? v : -v);
}
float perlin_noise_3d(float x, float y, float z) {
float floor_x = floorf(x);
float floor_y = floorf(y);
float floor_z = floorf(z);
int ix = floor_x;
int iy = floor_y;
int iz = floor_z;
x -= floor_x;
y -= floor_y;
z -= floor_z;
float u = fade(x);
float v = fade(y);
float w = fade(z);
int ia = perm_ref(ix ) + iy;
int ib = perm_ref(ix+1) + iy;
int iaa = perm_ref(ia ) + iz;
int iba = perm_ref(ib ) + iz;
int iab = perm_ref(ia+1) + iz;
int ibb = perm_ref(ib+1) + iz;
return lerp(w, lerp(v, lerp(u, grad3d(perm_ref(iaa ), x , y , z ),
grad3d(perm_ref(iba ), x-1, y , z )),
lerp(u, grad3d(perm_ref(iab ), x , y-1, z ),
grad3d(perm_ref(ibb ), x-1, y-1, z ))),
lerp(v, lerp(u, grad3d(perm_ref(iaa+1), x , y , z-1),
grad3d(perm_ref(iba+1), x-1, y , z-1)),
lerp(u, grad3d(perm_ref(iab+1), x , y-1, z-1),
grad3d(perm_ref(ibb+1), x-1, y-1, z-1))));
}
float perlin_fbm_3d(float x, float y, float z, int octave) {
float f = 0.0f;
float w = 0.5f;
for (int i = 0; i < octave; i++) {
f += w * perlin_noise_3d(x, y, z);
x *= 2.0f;
y *= 2.0f;
z *= 2.0f;
w *= 0.5f;
}
return f;
}