CrystalSpace

Public API Reference

CS::Math::Noise::Module::RidgedMulti Class Reference
[Generator Modules]

Noise module that outputs 3-dimensional ridged-multifractal noise. More...

#include <cstool/noise/module/ridgedmulti.h>

Inheritance diagram for CS::Math::Noise::Module::RidgedMulti:

List of all members.

Public Member Functions

double GetFrequency () const
 Returns the frequency of the first octave.
double GetLacunarity () const
 Returns the lacunarity of the ridged-multifractal noise.
CS::Math::Noise::NoiseQuality GetNoiseQuality () const
 Returns the quality of the ridged-multifractal noise.
int GetOctaveCount () const
 Returns the number of octaves that generate the ridged-multifractal noise.
int GetSeed () const
 Returns the seed value used by the ridged-multifractal-noise function.
virtual int GetSourceModuleCount () const
 Returns the number of source modules required by this noise module.
virtual double GetValue (double x, double y, double z) const
 Generates an output value given the coordinates of the specified input value.
 RidgedMulti ()
 Constructor.
void SetFrequency (double frequency)
 Sets the frequency of the first octave.
void SetLacunarity (double lacunarity)
 Sets the lacunarity of the ridged-multifractal noise.
void SetNoiseQuality (CS::Math::Noise::NoiseQuality noiseQuality)
 Sets the quality of the ridged-multifractal noise.
void SetOctaveCount (int octaveCount)
 Sets the number of octaves that generate the ridged-multifractal noise.
void SetSeed (int seed)
 Sets the seed value used by the ridged-multifractal-noise function.

Protected Member Functions

void CalcSpectralWeights ()
 Calculates the spectral weights for each octave.

Protected Attributes

double m_frequency
 Frequency of the first octave.
double m_lacunarity
 Frequency multiplier between successive octaves.
CS::Math::Noise::NoiseQuality m_noiseQuality
 Quality of the ridged-multifractal noise.
int m_octaveCount
 Total number of octaves that generate the ridged-multifractal noise.
double m_pSpectralWeights [RIDGED_MAX_OCTAVE]
 Contains the spectral weights for each octave.
int m_seed
 Seed value used by the ridged-multfractal-noise function.

Detailed Description

Noise module that outputs 3-dimensional ridged-multifractal noise.

moduleridgedmulti.png

This noise module, heavily based on the Perlin-noise module, generates ridged-multifractal noise. Ridged-multifractal noise is generated in much of the same way as Perlin noise, except the output of each octave is modified by an absolute-value function. Modifying the octave values in this way produces ridge-like formations.

Ridged-multifractal noise does not use a persistence value. This is because the persistence values of the octaves are based on the values generated from from previous octaves, creating a feedback loop (or that's what it looks like after reading the code.)

This noise module outputs ridged-multifractal-noise values that usually range from -1.0 to +1.0, but there are no guarantees that all output values will exist within that range.

Note:
For ridged-multifractal noise generated with only one octave, the output value ranges from -1.0 to 0.0.

Ridged-multifractal noise is often used to generate craggy mountainous terrain or marble-like textures.

This noise module does not require any source modules.

Octaves

The number of octaves control the amount of detail of the ridged-multifractal noise. Adding more octaves increases the detail of the ridged-multifractal noise, but with the drawback of increasing the calculation time.

An application may specify the number of octaves that generate ridged-multifractal noise by calling the SetOctaveCount() method.

Frequency

An application may specify the frequency of the first octave by calling the SetFrequency() method.

Lacunarity

The lacunarity specifies the frequency multipler between successive octaves.

The effect of modifying the lacunarity is subtle; you may need to play with the lacunarity value to determine the effects. For best results, set the lacunarity to a number between 1.5 and 3.5.

References & Acknowledgments

F. Kenton "Doc Mojo" Musgrave's texturing page - This page contains links to source code that generates ridged-multfractal noise, among other types of noise. The source file fractal.c contains the code I used in my ridged-multifractal class (see the RidgedMultifractal() function.) This code was written by F. Kenton Musgrave, the person who created MojoWorld. He is also one of the authors in Texturing and Modeling: A Procedural Approach (Morgan Kaufmann, 2002. ISBN 1-55860-848-6.)

Definition at line 127 of file ridgedmulti.h.


Constructor & Destructor Documentation

CS::Math::Noise::Module::RidgedMulti::RidgedMulti (  ) 

Constructor.

The default number of octaves is set to CS::Math::Noise::Module::DEFAULT_RIDGED_OCTAVE_COUNT.

The default frequency is set to CS::Math::Noise::Module::DEFAULT_RIDGED_FREQUENCY.

The default lacunarity is set to CS::Math::Noise::Module::DEFAULT_RIDGED_LACUNARITY.

The default seed value is set to CS::Math::Noise::Module::DEFAULT_RIDGED_SEED.


Member Function Documentation

void CS::Math::Noise::Module::RidgedMulti::CalcSpectralWeights (  )  [protected]

Calculates the spectral weights for each octave.

This method is called when the lacunarity changes.

double CS::Math::Noise::Module::RidgedMulti::GetFrequency (  )  const [inline]

Returns the frequency of the first octave.

Returns:
The frequency of the first octave.

Definition at line 150 of file ridgedmulti.h.

double CS::Math::Noise::Module::RidgedMulti::GetLacunarity (  )  const [inline]

Returns the lacunarity of the ridged-multifractal noise.

Returns:
The lacunarity of the ridged-multifractal noise.

The lacunarity is the frequency multiplier between successive octaves.

Definition at line 161 of file ridgedmulti.h.

CS::Math::Noise::NoiseQuality CS::Math::Noise::Module::RidgedMulti::GetNoiseQuality (  )  const [inline]

Returns the quality of the ridged-multifractal noise.

Returns:
The quality of the ridged-multifractal noise.

See CS::Math::Noise::NoiseQuality for definitions of the various coherent-noise qualities.

Definition at line 172 of file ridgedmulti.h.

int CS::Math::Noise::Module::RidgedMulti::GetOctaveCount (  )  const [inline]

Returns the number of octaves that generate the ridged-multifractal noise.

Returns:
The number of octaves that generate the ridged-multifractal noise.

The number of octaves controls the amount of detail in the ridged-multifractal noise.

Definition at line 185 of file ridgedmulti.h.

int CS::Math::Noise::Module::RidgedMulti::GetSeed (  )  const [inline]

Returns the seed value used by the ridged-multifractal-noise function.

Returns:
The seed value.

Definition at line 194 of file ridgedmulti.h.

virtual int CS::Math::Noise::Module::RidgedMulti::GetSourceModuleCount (  )  const [inline, virtual]

Returns the number of source modules required by this noise module.

Returns:
The number of source modules required by this noise module.

Implements CS::Math::Noise::Module::Module.

Definition at line 199 of file ridgedmulti.h.

virtual double CS::Math::Noise::Module::RidgedMulti::GetValue ( double  x,
double  y,
double  z 
) const [virtual]

Generates an output value given the coordinates of the specified input value.

Parameters:
x The x coordinate of the input value.
y The y coordinate of the input value.
z The z coordinate of the input value.
Returns:
The output value.
Precondition:
All source modules required by this noise module have been passed to the SetSourceModule() method.

Before an application can call this method, it must first connect all required source modules via the SetSourceModule() method. If these source modules are not connected to this noise module, this method raises a debug assertion.

To determine the number of source modules required by this noise module, call the GetSourceModuleCount() method.

Implements CS::Math::Noise::Module::Module.

void CS::Math::Noise::Module::RidgedMulti::SetFrequency ( double  frequency  )  [inline]

Sets the frequency of the first octave.

Parameters:
frequency The frequency of the first octave.

Definition at line 209 of file ridgedmulti.h.

void CS::Math::Noise::Module::RidgedMulti::SetLacunarity ( double  lacunarity  )  [inline]

Sets the lacunarity of the ridged-multifractal noise.

Parameters:
lacunarity The lacunarity of the ridged-multifractal noise.

The lacunarity is the frequency multiplier between successive octaves.

For best results, set the lacunarity to a number between 1.5 and 3.5.

Definition at line 223 of file ridgedmulti.h.

void CS::Math::Noise::Module::RidgedMulti::SetNoiseQuality ( CS::Math::Noise::NoiseQuality  noiseQuality  )  [inline]

Sets the quality of the ridged-multifractal noise.

Parameters:
noiseQuality The quality of the ridged-multifractal noise.

See CS::Math::Noise::NoiseQuality for definitions of the various coherent-noise qualities.

Definition at line 235 of file ridgedmulti.h.

void CS::Math::Noise::Module::RidgedMulti::SetOctaveCount ( int  octaveCount  )  [inline]

Sets the number of octaves that generate the ridged-multifractal noise.

Parameters:
octaveCount The number of octaves that generate the ridged-multifractal noise.
Precondition:
The number of octaves ranges from 1 to CS::Math::Noise::Module::RIDGED_MAX_OCTAVE.
Exceptions:
CS::Math::Noise::ExceptionInvalidParam An invalid parameter was specified; see the preconditions for more information.

The number of octaves controls the amount of detail in the ridged-multifractal noise.

The larger the number of octaves, the more time required to calculate the ridged-multifractal-noise value.

Definition at line 257 of file ridgedmulti.h.

void CS::Math::Noise::Module::RidgedMulti::SetSeed ( int  seed  )  [inline]

Sets the seed value used by the ridged-multifractal-noise function.

Parameters:
seed The seed value.

Definition at line 270 of file ridgedmulti.h.


Member Data Documentation

Frequency of the first octave.

Definition at line 283 of file ridgedmulti.h.

Frequency multiplier between successive octaves.

Definition at line 286 of file ridgedmulti.h.

Quality of the ridged-multifractal noise.

Definition at line 289 of file ridgedmulti.h.

Total number of octaves that generate the ridged-multifractal noise.

Definition at line 293 of file ridgedmulti.h.

Contains the spectral weights for each octave.

Definition at line 296 of file ridgedmulti.h.

Seed value used by the ridged-multfractal-noise function.

Definition at line 299 of file ridgedmulti.h.


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

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