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//
// Copyright (C) : Please refer to the COPYRIGHT file distributed
// with this source distribution.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
///////////////////////////////////////////////////////////////////////////////
#include <math.h>
#include "RandGen.h"
#include "PseudoNoise.h"
static const unsigned NB_VALUE_NOISE = 512;
real *PseudoNoise::_values;
PseudoNoise::PseudoNoise ()
{
}
void
PseudoNoise::init (long seed)
{
_values = new real[NB_VALUE_NOISE];
RandGen::srand48(seed);
for (unsigned int i=0; i<NB_VALUE_NOISE; i++)
_values[i] = -1.0 + 2.0 * RandGen::drand48();
}
real
PseudoNoise::linearNoise (real x)
{
int i = x*NB_VALUE_NOISE;
real x1=_values[i%NB_VALUE_NOISE], x2=_values[(i+1)%NB_VALUE_NOISE];
real t=x*real(NB_VALUE_NOISE)-real(i);
return x1*(1-t)+x2*t;
}
real
LanczosWindowed(real t)
{
if (fabs(t)>2) return 0;
if (fabs(t)<M_EPSILON) return 1.0;
return sin(M_PI*t)/(M_PI*t) * sin(M_PI*t/2.0)/(M_PI*t/2.0);
}
real
PseudoNoise::smoothNoise (real x)
{
int i = x*NB_VALUE_NOISE;
real t=x*real(NB_VALUE_NOISE)-real(i);
if (i - 1 < 0)
{
int plus=-i/NB_VALUE_NOISE;
i=i+NB_VALUE_NOISE*(plus+2);
t=(x+plus+2)*real(NB_VALUE_NOISE)-real(i);
}
real x1=_values[i%NB_VALUE_NOISE], x2=_values[(i+1)%NB_VALUE_NOISE];
real x0=_values[(i-1)%NB_VALUE_NOISE], x3=_values[(i+2)%NB_VALUE_NOISE];
real y0=LanczosWindowed(-1-t);
real y1=LanczosWindowed(-t);
real y2=LanczosWindowed(1-t);
real y3=LanczosWindowed(2-t);
// cerr<<"x0="<<x0<<" x1="<<x1<<" x2="<<x2<<" x3="<<x3<<endl;
// cerr<<"y0="<<y0<<" y1="<<y1<<" y2="<<y2<<" y3="<<y3<<" :";
return (x0*y0+x1*y1+x2*y2+x3*y3)/(y0+y1+y2+y3);
}
real
PseudoNoise::turbulenceSmooth (real x, unsigned nbOctave)
{
real y=0;
real k=1.0;
for (unsigned i=0; i<nbOctave; i++)
{
y=y+k*smoothNoise(x*k);
k=k/2.0;
}
return y;
}
real
PseudoNoise::turbulenceLinear (real x, unsigned nbOctave)
{
real y=0;
real k=1.0;
for (unsigned i=0; i<nbOctave; i++)
{
y=y+k*linearNoise(x*k);
k=k/2.0;
}
return y;
}
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