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/*=========================================================================
Program: Visualization Toolkit
Module: vtkPerlinNoise.cxx
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
#include "vtkPerlinNoise.h"
#include "vtkObjectFactory.h"
#include <math.h>
vtkStandardNewMacro(vtkPerlinNoise);
// These functions are from Greg Ward's recursive implementation in
// Graphics Gems II. I've kept the names the same for instructional
// purposes, and only changed things where optimizations could be made
// or where correctness fixes were necessary.
static double hermite(double p0, double p1,
double r0, double r1, double t)
{
double tt = t*t;
return (p0*((2.0*t - 3.0)*tt + 1.0) +
p1*(-2.0*t + 3.0)*tt +
r0*((t-2.0)*t+1.0)*t +
r1*(t-1.0)*tt);
}
// assumes 32 bit ints, but so it seems does VTK
static double frand(unsigned int s)
{
s = (s<<13) ^ s;
s = (s*(s*s*15731 + 789221)+1376312589)&VTK_INT_MAX;
return 1.0 - double(s)/(VTK_INT_MAX/2 + 1);
}
static void rand3abcd(int x, int y, int z, double outv[4])
{
outv[0] = frand(67*x + 59*y + 71*z);
outv[1] = frand(73*x + 79*y + 83*z);
outv[2] = frand(89*x + 97*y + 101*z);
outv[3] = frand(103*x + 107*y + 109*z);
}
static void interpolate(double f[4], int i, int n,
int xlim[3][2], double xarg[2])
{
double f0[4], f1[4];
if (n == 0)
{
rand3abcd(xlim[0][i&1], xlim[1][(i>>1) & 1], xlim[2][i>>2], f);
return;
}
n--;
interpolate(f0, i, n, xlim, xarg);
interpolate(f1, i | (1<<n), n, xlim, xarg);
f[0] = (1.0 - xarg[n])*f0[0] + xarg[n]*f1[0];
f[1] = (1.0 - xarg[n])*f0[1] + xarg[n]*f1[1];
f[2] = (1.0 - xarg[n])*f0[2] + xarg[n]*f1[2];
f[3] = hermite(f0[3], f1[3], f0[n], f1[n], xarg[n]);
}
static void perlinNoise(double x[3], double noise[4])
{
double xarg[3];
int xlim[3][2];
xlim[0][0] = int(floor(x[0]));
xlim[1][0] = int(floor(x[1]));
xlim[2][0] = int(floor(x[2]));
xlim[0][1] = xlim[0][0] + 1;
xlim[1][1] = xlim[1][0] + 1;
xlim[2][1] = xlim[2][0] + 1;
xarg[0] = x[0] - xlim[0][0];
xarg[1] = x[1] - xlim[1][0];
xarg[2] = x[2] - xlim[2][0];
interpolate(noise, 0, 3, xlim, xarg);
}
vtkPerlinNoise::vtkPerlinNoise()
{
this->Frequency[0] = 1.0;
this->Frequency[1] = 1.0;
this->Frequency[2] = 1.0;
this->Phase[0] = 0.0;
this->Phase[1] = 0.0;
this->Phase[2] = 0.0;
this->Amplitude = 1.0;
}
double vtkPerlinNoise::EvaluateFunction(double x[3])
{
double xd[3];
double noise[4];
xd[0] = x[0]*this->Frequency[0] - this->Phase[0]*2.0;
xd[1] = x[1]*this->Frequency[1] - this->Phase[1]*2.0;
xd[2] = x[2]*this->Frequency[2] - this->Phase[2]*2.0;
perlinNoise(xd, noise);
return noise[3]*this->Amplitude;
}
// Evaluate PerlinNoise gradient.
void vtkPerlinNoise::EvaluateGradient(double* vtkNotUsed(x), // Was x[3]
double n[3])
{
// contrary to the paper, the vector computed as a byproduct of
// the Perlin Noise computation isn't a gradient; it's a tangent.
// Doing this right will take some work.
n[0] = 0.0;
n[1] = 0.0;
n[2] = 0.0;
}
void vtkPerlinNoise::PrintSelf(ostream& os, vtkIndent indent)
{
this->Superclass::PrintSelf(os,indent);
os << indent << "Amplitude: " << this->Amplitude << "\n";
os << indent << "Frequency: ("
<< this->Frequency[0] << ", "
<< this->Frequency[1] << ", "
<< this->Frequency[2] << ")\n";
os << indent << "Phase: ("
<< this->Phase[0] << ", "
<< this->Phase[1] << ", "
<< this->Phase[2] << ")\n";
}
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