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#include <stdio.h>
#include <math.h>
struct perlin
{
int p[512];
};
static const int s_permutation[] = { 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 double fade (double t)
{
return t * t * t * (t * (t * 6 - 15) + 10);
}
static double lerp (double t, double a, double b)
{
return a + t * (b - a);
}
static double grad (int hash, double x, double y, double z)
{
int h = hash & 15; // CONVERT LO 4 BITS OF HASH CODE
double u = h < 8 || h == 12 || h == 13 ? x : y, // INTO 12 GRADIENT DIRECTIONS.
v = h < 4 || h == 12 || h == 13 ? y : z;
return ((h & 1) == 0 ? u : -u) + ((h & 2) == 0 ? v : -v);
}
double perlin_noise (struct perlin *this, double x, double y, double z)
{
int X = (int) floor (x) & 255, // FIND UNIT CUBE THAT
Y = (int) floor (y) & 255, // CONTAINS POINT.
Z = (int) floor (z) & 255;
x -= floor (x); // FIND RELATIVE X,Y,Z
y -= floor (y); // OF POINT IN CUBE.
z -= floor (z);
double u = fade (x), // COMPUTE FADE CURVES
v = fade (y), // FOR EACH OF X,Y,Z.
w = fade (z);
int A = this->p[X] + Y, AA = this->p[A] + Z, AB = this->p[A + 1] + Z, // HASH COORDINATES OF
B = this->p[X + 1] + Y, BA = this->p[B] + Z, BB = this->p[B + 1] + Z; // THE 8 CUBE CORNERS,
return lerp (w, lerp (v, lerp (u, grad (this->p[AA], x, y, z), // AND ADD
grad (this->p[BA], x - 1, y, z)), // BLENDED
lerp (u, grad (this->p[AB], x, y - 1, z), // RESULTS
grad (this->p[BB], x - 1, y - 1, z))), // FROM 8
lerp (v, lerp (u, grad (this->p[AA + 1], x, y, z - 1), // CORNERS
grad (this->p[BA + 1], x - 1, y, z - 1)), // OF CUBE
lerp (u, grad (this->p[AB + 1], x, y - 1, z - 1),
grad (this->p[BB + 1], x - 1, y - 1, z - 1))));
}
void perlin_init (struct perlin *this)
{
int i;
for (i = 0; i < 256; i++)
{
this->p[256 + i] = this->p[i] = s_permutation[i];
}
}
/* exemple certainement faux ou inutile, car je sais pas de quoi il s'agit... */
int main (void)
{
struct perlin myperlin = { {0} };
perlin_init (&myperlin);
{
int i;
for (i = 0; i < 10; i++)
{
double val = perlin_noise (&myperlin, 12.34, 56.78, 90.12);
printf ("val = %f\n", val);
}
}
return 0;
} |
