CWE-ou-minkata/Sources/Plasma/PubUtilLib/plMath/hsNoiseFunc.cpp

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*==LICENSE==*/
#include "hsNoiseFunc.h"
#include "HeadSpin.h"

#include "hsGeometry3.h"

hsNoiseFunc::hsNoiseFunc() 
{
}

hsNoiseFunc::~hsNoiseFunc() 
{
}

void hsNoiseFunc::Seed(uint32_t s)
{
    srand(s);
}

hsTableNoise::hsTableNoise()
: fTable(nil), fTableLen(0)
{
}

hsTableNoise::~hsTableNoise()
{
    delete [] fTable;
}

void hsTableNoise::SetTable(int len, float* arr)
{
    fTableLen = len;

    delete [] fTable;
    if( !len )
    {
        fTable = nil;
        return;
    }

    fTable = new float[len+2];

    int i;
    for( i = 0; i < len; i++ )
        fTable[i] = arr[i];
    fTable[i++] = fTable[i-1];
    fTable[i++] = fTable[i-1];

}

float hsTableNoise::Noise(float lo, float hi, float t)
{
    hsAssert(fTableLen, "Badly initialized table noise function");

    float r = float(rand()) / float(RAND_MAX);
    r = lo + (hi - lo) * r;

    if( t < 0 )
        t = 0;
    else if( t > 1.f )
        t = 1.f;

    float tIdx = t * fTableLen;
    uint32_t idx = uint32_t(tIdx);
    float frac = tIdx - float(idx);
    hsAssert((idx >= 0)&&(idx <= fTableLen), "Noise parm t out of range [0..1]");

    float scale = fTable[idx] + (fTable[idx+1] - fTable[idx]) * frac;
    
    r *= scale;

    return r;
}

float hsTableNoise::NoisePoint(const hsPoint3& p, float lo, float hi, float t)
{
    hsAssert(fTableLen, "Badly initialized table noise function");

    uint32_t sX = *((uint32_t*)&p.fX);
    uint32_t sY = *((uint32_t*)&p.fY);
    uint32_t sZ = *((uint32_t*)&p.fZ);

    uint32_t sAll = ((((sX & 0x07800000) >> 16) | ((sX & 0x007fffff) >> 17)) << 20)
                | ((((sY & 0x07800000) >> 16) | ((sY & 0x007fffff) >> 17)) << 10)
                | ((((sZ & 0x07800000) >> 16) | ((sZ & 0x007fffff) >> 17))      );

    const uint32_t kExp = 0x3f800000;
    const uint32_t kMsk = 0x007fffff;

    const uint32_t kA = 1665636L;
    const uint32_t kC = 1013904223L;

    uint32_t iR = kA * sAll + kC;
    iR &= kMsk;
    iR |= kExp;

    float r = (*(float*)&iR) - 1.f;

    r = lo + (hi - lo) * r;

    if( t < 0 )
        t = 0;
    else if( t > 1.f )
        t = 1.f;

    float tIdx = t * fTableLen;
    uint32_t idx = uint32_t(tIdx);
    float frac = tIdx - float(idx);
    hsAssert((idx >= 0)&&(idx <= fTableLen), "Noise parm t out of range [0..1]");

    float scale = fTable[idx] + (fTable[idx+1] - fTable[idx]) * frac;
    
    r *= scale;

    return r;
}