genesis-3d_engine/Engine/foundation/math/noise.h

/****************************************************************************
Copyright (c) 2006, Radon Labs GmbH
Copyright (c) 2011-2013,WebJet Business Division,CYOU
 
http://www.genesis-3d.com.cn

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
****************************************************************************/

#pragma once
#ifndef MATH_NOISE_H
#define MATH_NOISE_H
//------------------------------------------------------------------------------
/**
    @class Math::noise
    
    Perlin noise class.
    
    See http://mrl.nyu.edu/~perlin/noise/ for details.

*/
#include "core/types.h"

//------------------------------------------------------------------------------
namespace Math
{
class noise
{
public:
    /// generate noise value
    static float gen(float x, float y, float z);

private:
    /// compute fade curve
    static float fade(float t);
    /// lerp between a and b
    static float lerp(float t, float a, float b);
    /// convert into gradient direction
    static float grad(int hash, float x, float y, float z);

    static int perm[512];
};

int noise::perm[512] =  {60,137,91,90,15,
   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
   };

//------------------------------------------------------------------------------
/**
*/
inline
float
noise::fade(float t)
{
    return t * t * t * (t * (t * 6.0f - 15.0f) + 10.0f);
}

//------------------------------------------------------------------------------
/**
*/
inline
float
noise::lerp(float t, float a, float b)
{
    return a + t * (b - a);
}

//------------------------------------------------------------------------------
/**
*/
inline
float
noise::grad(int hash, float x, float y, float z)
{
    int h = hash & 15;
    float u = h < 8 ? x : y;
    float v = h < 4 ? y : ((h == 12) || (h==14)) ? x : z;
    return ((h & 1) == 0 ? u : -u) + ((h & 2) == 0 ? v : -v);
}

//------------------------------------------------------------------------------
/**
*/
inline
float
noise::gen(float x, float y, float z)
{
    float floorX = floorf(x);
    float floorY = floorf(y);
    float floorZ = floorf(z);

    // find unit cube that contains point
    int X = int(floorX) & 255;
    int Y = int(floorY) & 255;
    int Z = int(floorZ) & 255;

    // find relative x,y,z of point in cube
    x -= floorX;
    y -= floorY;
    z -= floorZ;

    // compute fade curves for x, y, z
    float u = fade(x);
    float v = fade(y);
    float w = fade(z);

    // hash coords of 8 cube corners
    int A  = perm[X] + Y;
    int AA = perm[A] + Z;
    int AB = perm[A+1] + Z;
    int B  = perm[X+1] + Y;
    int BA = perm[B] + Z;
    int BB = perm[B+1] + Z;

    // add blended results from 8 corners of cube
    return lerp(w, lerp(v, lerp(u, grad(perm[AA  ], x  , y  , z   ),
                                   grad(perm[BA  ], x-1, y  , z   )),
                           lerp(u, grad(perm[AB  ], x  , y-1, z   ),
                                   grad(perm[BB  ], x-1, y-1, z   ))),
                   lerp(v, lerp(u, grad(perm[AA+1], x  , y  , z-1 ),
                                   grad(perm[BA+1], x-1, y  , z-1 )),
                           lerp(u, grad(perm[AB+1], x  , y-1, z-1 ),
                                   grad(perm[BB+1], x-1, y-1, z-1 ))));
}

} // namespace Math
//------------------------------------------------------------------------------
#endif