Generates multirate noise using a hierarchical tree structure. More...

#include "noise_generators.h"

Inheritance diagram for noise::MultirateGenerator:

Collaboration diagram for noise::MultirateGenerator:

Public Member Functions
	MultirateGenerator (std::mt19937 &rngEngine, RealType alpha, unsigned branches)
	Constructor to initialize the multirate generator.

RealType	getSample () override
	Generates a multirate noise sample.

void	skipSamples (std::size_t samples) noexcept
	Skips a number of samples in the noise sequence.

void	reset () noexcept
	Resets the noise generator state.

Detailed Description

Generates multirate noise using a hierarchical tree structure.

Definition at line 118 of file noise_generators.h.

Constructor & Destructor Documentation

◆ MultirateGenerator()

noise::MultirateGenerator::MultirateGenerator	(	std::mt19937 &	rngEngine,
		RealType	alpha,
		unsigned	branches
	)

Constructor to initialize the multirate generator.

Parameters

rngEngine	The random number engine to use for generation.
alpha	The scaling parameter that controls the noise properties.
branches	The number of branches in the tree structure.

Definition at line 24 of file noise_generators.cpp.

                                                                                                               :
        _rng_engine(rngEngine)
    {
        const RealType beta = -(alpha - 2) / 2.0;
        const int fint = static_cast<int>(std::floor(beta));
        const RealType ffrac = std::fmod(beta, 1.0);
 
        createTree(ffrac, fint, branches);
        // TODO: verify scale factor calculation (* 2.0 appears to be a bug)
        _scale = 1.0 / std::pow(10.0, (-alpha + 2.0) * 2.0);
    }

Member Function Documentation

◆ getSample()

RealType noise::MultirateGenerator::getSample ( )

overridevirtual

Generates a multirate noise sample.

Returns: A noise sample of type RealType.

Implements noise::NoiseGenerator.

Definition at line 135 of file noise_generators.h.

135{ return _topbranch->getSample() * _scale; }

◆ reset()

void noise::MultirateGenerator::reset ( )

noexcept

Resets the noise generator state.

Definition at line 91 of file noise_generators.cpp.

    {
        std::vector<FAlphaBranch*> branches;
        FAlphaBranch* branch = _topbranch.get();
 
        while (branch != nullptr)
        {
            branches.push_back(branch);
            branch = branch->getPre();
        }
 
        for (const auto& b : std::ranges::reverse_view(branches))
        {
            b->flush(1.0);
        }
    }

References noise::FAlphaBranch::flush(), and noise::FAlphaBranch::getPre().

Here is the call graph for this function:

◆ skipSamples()

void noise::MultirateGenerator::skipSamples ( std::size_t samples )

noexcept

Skips a number of samples in the noise sequence.

Parameters

samples The number of samples to skip.

Definition at line 37 of file noise_generators.cpp.

    {
        if (samples == 0)
        {
            return;
        }
 
        if (const int skip_branches = static_cast<int>(std::log10(static_cast<double>(samples))) - 1; skip_branches > 0)
        {
            std::vector<FAlphaBranch*> flushbranches;
            FAlphaBranch* branch = _topbranch.get();
 
            for (int i = 0; i < skip_branches && (branch != nullptr); ++i)
            {
                flushbranches.push_back(branch);
                branch = branch->getPre();
            }
 
            if (branch != nullptr)
            {
                const auto reduced_samples =
                    samples / static_cast<std::size_t>(std::pow(10.0, static_cast<double>(skip_branches)));
                for (std::size_t i = 0; i < reduced_samples; ++i)
                {
                    branch->getSample();
                }
            }
 
            for (const auto& fb : std::ranges::reverse_view(flushbranches))
            {
                fb->flush(1.0);
            }
        }
        else
        {
            for (std::size_t i = 0; i < samples; ++i)
            {
                _topbranch->getSample();
            }
        }
    }

References noise::FAlphaBranch::getPre(), and noise::FAlphaBranch::getSample().