noise1.cpp

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// $Id: noise1.cpp 751 2006-03-31 15:43:49Z alex $
// noise1.cpp
//
// Author  : Mike
// Purpose : Implemetation of low level noise function calls.
//           It uses a quadratic B-Spline instead of the cubic Hermite interpolant 
//           implied by Perlin. Also note that DNoise is just the x, y, and z 
//           derivatives of Noise (which are also B-Splines).
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 */

// Version : 1.0
// Started : 20/01/96

#include "camtypes.h"
#include "macros.h"
#include "vector3d.h"
#include "noisebas.h"
#include "noise1.h"

#define TABLEWIDTH 50                       // we can reduce this at the expense
#define MAXPTS     (TABLEWIDTH*TABLEWIDTH)  // of randomness.

/**************************************************************************************
>   NoiseGen1::NoiseGen1()
***************************************************************************************/

NoiseGen1::NoiseGen1()
{
    RTable=NULL;
}

/**************************************************************************************
>   NoiseGen1::~NoiseGen1()
***************************************************************************************/

NoiseGen1::~NoiseGen1()
{
    if (RTable!=NULL)
    {
        free((void*)RTable);
        RTable=NULL;
    }
}

/**************************************************************************************

>   virtual BOOL NoiseGen1::Initialise()

    Aurthor:    Mike
    Created:    07/07/96
    Purpose:    Initialise all the data tables we need to get this noise generator
                going. This particular table holds random float values in the range
                [0..1]

***************************************************************************************/

BOOL NoiseGen1::Initialise()
{
    // allocate some space big enough
    RTable = (float*)malloc(MAXPTS * sizeof(float));
    if (RTable==NULL)
        return FALSE;

    // create the table
    SeedTable(0);
    return TRUE;
}


/**************************************************************************************

>   void NoiseGen1::SeedTable(UINT32 seed)

    Aurthor:    Mike
    Created:    07/07/96
    Inputs:     seed = the seed to use as an initial value in our random number table
    Purpose:    Seed the random number table we use.

***************************************************************************************/

void NoiseGen1::SeedTable(UINT32 seed)
{
    if (RTable!=NULL)
    {
        // seed the random number generator for consitency
        srand(seed);
        // now create those random impulses!
        // ok I'm assuming rand() will be compiled in and not a opsys level call.
        for (INT32 i=0; i<MAXPTS; i++)
            RTable[i] = (float)rand() / ((float)RAND_MAX);
    }
}


/**************************************************************************************

>   double NoiseGen1::VNoise1D(const Vector3D &p, double scale)

    Author:     Mike_Kenny (Xara Group Ltd) <camelotdev@xara.com>
    Created:    27/01/97
    Inputs:     p = a three dimensional vector
                scale = a scaling factor
    Returns:    A double f, 0<=f<=1.0

    Notes:      Uses 2d quadratic B-Spline smoothing

                1d quadratic bsplines are defined as...

                    C0 = 1 - 2u +  u^2
                    C1 = 1 + 2u - 2u^2
                    C2 =           u^2

                    v = (C0*p0 + C1*p1 + C2*p2)/2       0<=u<=1

                Note, this spline is a none-interpolating spline, i.e. it tends towards
                the points but never passes through any! This doesn't matter to us as 
                we're interpolating random impulses. 
                To make our tile cyclic, wrap coordinates at the edges.
                Also note, give points { p0,p1,p2 } the curve lives in the region [p0,p1]
                i.e. it is does not cover all p0..p2. To get segment [p1,p2] you'll
                need { p1,p2,p3 }
                Calculating the cyclic curve through p0,p1,p2,p3
                fit...
                  [p0,p1] = CF{ p0,p1,p2 }
                  [p1,p2] = CF{ p1,p2,p3 }
                  [p2,p3] = CF{ p2,p3,p0 }
                  [P3,P0] = CF{ p3,p0,p1 }
                i.e. 4 input points = 4 curves = 4 intervals 

***************************************************************************************/

double NoiseGen1::VNoise1D(const Vector3D &p, double scale)
{
    float  x2, x1, x0, y2, y1, y0, xf, yf;
    float  p00, p01, p02;
    INT32    ax, bx, cx;
    INT32    ay, by, cy;
    INT32    samplerange;

    // multiplying by TABLEWIDTH rather than (TABLEWIDTH-1)
    // forces a wrapping as our range is 0..TABLEWIDTH-1
    samplerange = (INT32)(scale); // *TABLEWIDTH);

    if (samplerange<1)
        return 0.0;
    
    // essentially ignore p.z (the calling routine sets it to 0)
    xf = ((float)p.x) * samplerange;
    yf = ((float)p.y) * samplerange;
    
    // index the 9 random impulses we'll used for (xf,yf)
    ax = (INT32)floor(xf);
    ay = (INT32)floor(yf);

    // calculate the 2d bspline blending coefs
    xf = xf - ax;               // u        (i.e. fract(p.x) 0..1)
    yf = yf - ay;               // v        (i.e. fract(p.y) 0..1)
    x1 = xf * xf;               // u^2
    y1 = yf * yf;               // v^2
    x2 = 0.5f * x1;             // u^2/2
    y2 = 0.5f * y1;             // v^2/2
    x1 = 0.5f + xf - x1;        // 0.5 + u - u^2
    y1 = 0.5f + yf - y1;        // 0.5 + v - v^2
    x0 = 0.5f - xf + x2;        // 0.5 - u + u^2/2
    y0 = 0.5f - yf + y2;        // 0.5 - v + v^2/2

    // get the next neighbours
    bx = ax + 1;
    by = ay + 1;
    cx = bx + 1;
    cy = by + 1;

    // do a potential double modulus as follows...
    //
    // 0 1 2 3 4 5 6 7 8 9  a b c d e f       index into impulse table
    // 0 1 2 3 4 5 6 7 0 1  2 3 4 5 6 7  ...  samplerange == 8
    // 0 1 2 3 4 0 1 2 0 1  2 3 4 0 1 2  ...   tablewidth == 5
    // ^               ^
    // notice the important symmetry of the values at either end of sample range
    // this gives tileable noise.

    ax = ax % samplerange;      // all 0 if samplerange == 1
    ay = ay % samplerange;
    bx = bx % samplerange;
    by = by % samplerange;
    cx = cx % samplerange;
    cy = cy % samplerange;

    if (samplerange==1)         // do something at zero if poss
        cx=cy=1;        

    if (TABLEWIDTH<samplerange)
    {
        // if our random impulse table is smaller than samplerange
        // then we need to mod into it.
        ax = ax % TABLEWIDTH;
        ay = ay % TABLEWIDTH;
        bx = bx % TABLEWIDTH;
        by = by % TABLEWIDTH;
        cx = cx % TABLEWIDTH;
        cy = cy % TABLEWIDTH;
    }

    ay*=TABLEWIDTH;
    by*=TABLEWIDTH;
    cy*=TABLEWIDTH;

    // read and interpolate the impulse values
    p00 = RTable[ax+ay];
    p01 = RTable[bx+ay];
    p02 = RTable[cx+ay];

    xf  = y0 * (x0*p00 + x1*p01 + x2*p02);

    p00 = RTable[ax+by];
    p01 = RTable[bx+by];
    p02 = RTable[cx+by];

    xf += y1 * (x0*p00 + x1*p01 + x2*p02);

    p00 = RTable[ax+cy];
    p01 = RTable[bx+cy];
    p02 = RTable[cx+cy];

    xf += y2 * (x0*p00 + x1*p01 + x2*p02);
    
    return (double)xf;
}


/*
double NoiseGen1::VNoise1D(const Vector3D &p, double scale)
{
    float  x2, x1, x0, y2, y1, y0, xf, yf;
    float  p00, p01, p02;
    INT32    ax, bx, cx;
    INT32    ay, by, cy;
    INT32    width;

    width = (INT32)(scale);
    
    // essentially ignore p.z (the calling routine sets it to 0)
    xf = ((float)p.x) * width;
    yf = ((float)p.y) * width;
    
    // index the 9 random impulses we'll used for (xf,yf)
    ax = (INT32)floor(xf);
    ay = (INT32)floor(yf);
    bx = ax+1;
    by = ay+1;
    cx = bx+1;
    cy = by+1;

    // modulo the width we're using
    if (cx>=width)
    {
        cx-=width;
        if (bx>=width)
        {
            bx-=width;
            if (ax>=width)
                ax-=width;
        }
    }

    if (cy>=width)
    {
        cy-=width;
        if (by>=width)
        {
            by-=width;
            if (ay>=width)
                ay-=width;
        }
    }

    // calculate the 2d bspline blending coefs

    xf = xf - ax;               // u        (i.e. fract(p.x) 0..1)
    yf = yf - ay;               // v        (i.e. fract(p.y) 0..1)
    x1 = xf * xf;               // u^2
    y1 = yf * yf;               // v^2
    x2 = 0.5f * x1;             // u^2/2
    y2 = 0.5f * y1;             // v^2/2
    x1 = 0.5f + xf - x1;        // 0.5 + u - u^2
    y1 = 0.5f + yf - y1;        // 0.5 + v - v^2
    x0 = 0.5f - xf + x2;        // 0.5 - u + u^2/2
    y0 = 0.5f - yf + y2;        // 0.5 - v + v^2/2

    ay*=TABLEWIDTH;
    by*=TABLEWIDTH;
    cy*=TABLEWIDTH;

    // read and interpolate the impulse values
    p00 = RTable[ax+ay];
    p01 = RTable[bx+ay];
    p02 = RTable[cx+ay];

    xf  = y0 * (x0*p00 + x1*p01 + x2*p02);

    p00 = RTable[ax+by];
    p01 = RTable[bx+by];
    p02 = RTable[cx+by];

    xf += y1 * (x0*p00 + x1*p01 + x2*p02);

    p00 = RTable[ax+cy];
    p01 = RTable[bx+cy];
    p02 = RTable[cx+cy];

    xf += y2 * (x0*p00 + x1*p01 + x2*p02);
    
    return (double)xf;
}
*/

/**************************************************************************************

>   Vector3D NoiseGen1::VNoise3D(const Vector3D &v)

    Purpose:    Vector-valued version of "Noise"

***************************************************************************************/

Vector3D NoiseGen1::VNoise3D(const Vector3D &p)
{
    return Vector3D(0,0,0);
}

---