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Perlin1D Class Reference

Encapsulates a perlin noise generator in one-dimension. More...

#include <Noise.h>

List of all members.

Public Types
enum	Interpolation { LINEAR, COSINE, CUBIC }
Public Methods
	Perlin1D (double persistence=0.5, int octaves=1, Interpolation interpolation=LINEAR)
	Construct a new perline noise generator.
void	setParameters (double persistence, int octaves)
	Set the noise parameters.
void	setInterpolation (Interpolation interpolation)
	Set the interpolation method.
void	setOffset (int idx)
	Set the offset into the noise functions.
void	randomize ()
	Randomize the offset.
double	_simpleRandom (int x) const
	A simple pseudo-random number regenator.
double	_getSmoothedNoise (int x)
	Get a weighted sum of adjacent random numbers to smooth the distribution.
double	_linearInterpolate (double a, double b, double x)
	Linear interpolation.
double	_cosineInterpolate (double a, double b, double x)
	Cosine interpolation.
double	_cubicInterpolate (double v0, double v1, double v2, double v3, double x)
	Cubic interpolation.
double	_getInterpolatedNoise (double x)
	Returns the noise value interpolated between the smoothed noise at successive points in the distribution.
double	getValue (double x)
	Get the noise vaule at a particular position.
std::vector< float >	generate (int n, bool periodic, double scale=1.0, double amplitude=1.0, double offset=0.0)
	Generate a list of noise values.

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Detailed Description

Encapsulates a perlin noise generator in one-dimension.

Many introductions to perlin noise and its uses are available online, via Google. Here's one such site:

http://freespace.virgin.net/hugo.elias/models/m_perlin.htm

Author:

Mark Rose <mrose@stm.lbl.gov>

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Member Enumeration Documentation

enum Perlin1D::Interpolation

Enumeration values: LINEAR  COSINE  CUBIC

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Constructor & Destructor Documentation

NAMESPACE_SIMDATA Perlin1D::Perlin1D (  double    persistence = 0.5, int    octaves = 1, Interpolation    interpolation = LINEAR )

Construct a new perline noise generator. Parameters: persistence  scale factor between succesive octaves octaves  number of octaves to generate interpolation  the method of interpolation between noise values

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Member Function Documentation

double Perlin1D::_cosineInterpolate (  double    a, double    b, double    x )  [inline]

Cosine interpolation. Parameters: a  the first value b  the second value x  the fraction from a to b (0-1) Returns: the interpolated value

double Perlin1D::_cubicInterpolate (  double    v0, double    v1, double    v2, double    v3, double    x )  [inline]

Cubic interpolation. Parameters: v0  value(i-1) v1  value(i) v2  value(i+1) v3  value(i+2) x  the fraction from v1 to v2 (0-1) Returns: the interpolated value

double Perlin1D::_getInterpolatedNoise (  double    x )

Returns the noise value interpolated between the smoothed noise at successive points in the distribution. Parameters: x  the point in the distribution Returns: the smoothed, interpolated noise value

double Perlin1D::_getSmoothedNoise (  int    x )  [inline]

Get a weighted sum of adjacent random numbers to smooth the distribution. Parameters: x  the central point for the weighted sum Returns: the weighted sum

double Perlin1D::_linearInterpolate (  double    a, double    b, double    x )  [inline]

Linear interpolation. Parameters: a  the first value b  the second value x  the fraction from a to b (0-1) Returns: the interpolated value

double Perlin1D::_simpleRandom (  int    x )  const [inline]

A simple pseudo-random number regenator. Parameters: x  the random seed. Returns: a pseudo-random number in the range 0-1.

std::vector< float > Perlin1D::generate (  int    n, bool    periodic, double    scale = 1.0, double    amplitude = 1.0, double    offset = 0.0 )

Generate a list of noise values. This is a convenience method to pregenerate a discrete perlin noise field. Both perioidic and aperiodic fields can be created (the former have the same value at the start and at the end). The noise field can be scaled in X and Y (e.g. time and amplitude), as well as offset so that the mean value is non-zero. Parameters: n  the number of noise values periodic  if true, the lists ends are blended to make them continuous scale  the scaling factor from the list index to the noise function amplitude  the noise amplitude offset  the noise offset

double Perlin1D::getValue (  double    x )

Get the noise vaule at a particular position. Parameters: x  the point in the distribution Returns: the noise value

void Perlin1D::randomize (    )

Randomize the offset. Subsequent noise will generally be uncorrelated to previously generated noise. Be aware that the random offset is in the range 10^9, so for large noise sets this property will break down.

void Perlin1D::setInterpolation (  Interpolation    interpolation )

Set the interpolation method. Parameters: interpolation  the method of interpolation between noise values

void Perlin1D::setOffset (  int    idx )

Set the offset into the noise functions. The offset can be used to reproducibly generate a given noise distribution, or to create independent finite noise distributions from the same generator.

void Perlin1D::setParameters (  double    persistence, int    octaves )

Set the noise parameters. Parameters: persistence  scale factor between succesive octaves octaves  number of octaves to generate

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The documentation for this class was generated from the following files:

• Noise.h
• Noise.cpp

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SimData version pre-0.4.0. For more information on SimData, visit the SimData Homepage. Generated on Tue Oct 14 12:06:42 2003, using Doxygen 1.2.18.