Perlin Noise algorithms(备忘)

 

//---------------------------------------------------------------------------------------
// Perlin Noise data  (copyed form ogre ver1.6.1)
//---------------------------------------------------------------------------------------
int perlin[512] = 
{
    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,

    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
};

#define fade(t) ( (t) * (t) * (t) * (t) * ( (t) * ( (t) * 6 - 15 ) + 10) )
inline 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);
}


inline double noise3(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 = perlin[X  ]+Y, AA = perlin[A]+Z, AB = perlin[A+1]+Z,      // HASH COORDINATES OF
        B = perlin[X+1]+Y, BA = perlin[B]+Z, BB = perlin[B+1]+Z;      // THE 8 CUBE CORNERS,

    return lerp(w, lerp(v, lerp(u, grad(perlin[AA  ], x  , y  , z   ),  // AND ADD
                        grad(perlin[BA  ], x-1, y  , z   )), // BLENDED
                    lerp(u, grad(perlin[AB  ], x  , y-1, z   ),  // RESULTS
                        grad(perlin[BB  ], x-1, y-1, z   ))),// FROM  8
                lerp(v, lerp(u, grad(perlin[AA+1], x  , y  , z-1 ),  // CORNERS
                        grad(perlin[BA+1], x-1, y  , z-1 )), // OF CUBE
                    lerp(u, grad(perlin[AB+1], x  , y-1, z-1 ),
                        grad(perlin[BB+1], x-1, y-1, z-1 ))));
}