Platform-independent piecewise constant distribution. More...

#include <PRNGDistribution.hpp>

Classes
struct	param_type
	Parameter set for the distribution. More...

Public Types
using	result_type = RealType
	The type of values produced by the distribution.

Public Member Functions
	PiecewiseConstantDistribution ()
	Default constructor. Creates uniform distribution over [0, 1).

template<typename InputIteratorB , typename InputIteratorW >
	PiecewiseConstantDistribution (InputIteratorB first_b, InputIteratorB last_b, InputIteratorW first_w)
	Constructs from interval boundaries and density weights.

template<typename UnaryOperation >
	PiecewiseConstantDistribution (std::initializer_list< RealType > bl, UnaryOperation fw)
	Constructs from interval boundaries and weight function.

template<typename UnaryOperation >
	PiecewiseConstantDistribution (size_t nw, RealType xmin, RealType xmax, UnaryOperation fw)
	Constructs with evenly-spaced intervals and weight function.

	PiecewiseConstantDistribution (const param_type &param)
	Constructs from a parameter set.

void	reset ()
	Resets the distribution state.

std::vector< RealType >	intervals () const
	Returns the interval boundaries.

std::vector< double >	densities () const
	Returns the density values.

param_type	param () const
	Gets the current parameter set.

void	param (const param_type &param)
	Sets new parameters for the distribution.

result_type	min () const
	Gets the minimum value that can be generated.

result_type	max () const
	Gets the maximum value that can be generated.

template<typename Generator >
result_type	operator() (Generator &g)
	Generates the next random value using stored parameters.

template<typename Generator >
result_type	operator() (Generator &g, const param_type &param)
	Generates the next random value using provided parameters.

Friends
bool	operator== (const PiecewiseConstantDistribution &lhs, const PiecewiseConstantDistribution &rhs)

bool	operator!= (const PiecewiseConstantDistribution &lhs, const PiecewiseConstantDistribution &rhs)

Detailed Description

template<typename RealType = double>
class Infinity::Engine::PiecewiseConstantDistribution< RealType >

Platform-independent piecewise constant distribution.

Produces real values from a distribution defined by a piecewise constant density function. The range is divided into intervals, each with a constant probability density, allowing you to approximate arbitrary probability distributions or create custom probability landscapes for procedural generation.

This distribution is extremely useful for creating non-uniform spatial distributions, modeling multi-modal data, approximating complex probability distributions, or implementing custom probability functions that can't be expressed with standard distributions.

Template Parameters

RealType Floating point type (float or double)

Example usage:

PRNG rng(12345);
 
// Three intervals with different densities
std::vector<float> intervals = {0.0f, 1.0f, 2.0f, 3.0f};
std::vector<double> densities = {0.5, 2.0, 0.5};  // Middle interval more likely
PiecewiseConstantDistribution<float> dist(
    intervals.begin(), intervals.end(),
    densities.begin()
);
float value = dist(rng);
 
// Biome distribution: different probabilities in different elevation ranges
PiecewiseConstantDistribution<float> elevation(
    {0.0f, 100.0f, 500.0f, 1000.0f},  // Interval boundaries
    [](float x) { return x < 250.0f ? 1.0 : 0.3; }  // Lower elevations more common
);
 
// Resource density map with hot spots
auto density_fn = [](double x) {
    return (x > 0.3 && x < 0.7) ? 5.0 : 1.0;  // High density in middle
};
PiecewiseConstantDistribution<double> resources(10, 0.0, 1.0, density_fn);

Note: Densities are automatically normalized to integrate to 1.; Returns values within the specified interval range.; Each interval has constant density - use PiecewiseLinearDistribution for smooth transitions.; Useful for approximating empirical distributions or complex PDFs.

Member Typedef Documentation

◆ result_type

template<typename RealType = double>

using Infinity::Engine::PiecewiseConstantDistribution< RealType >::result_type = RealType

The type of values produced by the distribution.

Constructor & Destructor Documentation

◆ PiecewiseConstantDistribution() [1/5]

template<typename RealType = double>

Infinity::Engine::PiecewiseConstantDistribution< RealType >::PiecewiseConstantDistribution ( )

inline

Default constructor. Creates uniform distribution over [0, 1).

◆ PiecewiseConstantDistribution() [2/5]

template<typename RealType = double>

template<typename InputIteratorB , typename InputIteratorW >

Infinity::Engine::PiecewiseConstantDistribution< RealType >::PiecewiseConstantDistribution	(	InputIteratorB	first_b,
		InputIteratorB	last_b,
		InputIteratorW	first_w
	)

inline

Constructs from interval boundaries and density weights.

Template Parameters

InputIteratorB	Iterator type for boundaries
InputIteratorW	Iterator type for weights

Parameters

first_b	Iterator to first boundary
last_b	Iterator past last boundary
first_w	Iterator to first weight

◆ PiecewiseConstantDistribution() [3/5]

template<typename RealType = double>

template<typename UnaryOperation >

Infinity::Engine::PiecewiseConstantDistribution< RealType >::PiecewiseConstantDistribution	(	std::initializer_list< RealType >	bl,
		UnaryOperation	fw
	)

inline

Constructs from interval boundaries and weight function.

Template Parameters

UnaryOperation Function type

Parameters

bl	Initializer list of interval boundaries
fw	Weight function

◆ PiecewiseConstantDistribution() [4/5]

template<typename RealType = double>

template<typename UnaryOperation >

Infinity::Engine::PiecewiseConstantDistribution< RealType >::PiecewiseConstantDistribution	(	size_t	nw,
		RealType	xmin,
		RealType	xmax,
		UnaryOperation	fw
	)

inline

Constructs with evenly-spaced intervals and weight function.

Template Parameters

UnaryOperation Function type

Parameters

nw	Number of intervals
xmin	Minimum boundary
xmax	Maximum boundary
fw	Weight function

◆ PiecewiseConstantDistribution() [5/5]

template<typename RealType = double>

Infinity::Engine::PiecewiseConstantDistribution< RealType >::PiecewiseConstantDistribution ( const param_type & param )

inlineexplicit

Constructs from a parameter set.

Parameters

param The distribution parameters

Member Function Documentation

◆ densities()

template<typename RealType = double>

std::vector< double > Infinity::Engine::PiecewiseConstantDistribution< RealType >::densities ( ) const

inline

Returns the density values.

◆ intervals()

template<typename RealType = double>

std::vector< RealType > Infinity::Engine::PiecewiseConstantDistribution< RealType >::intervals ( ) const

inline

Returns the interval boundaries.

◆ max()

template<typename RealType = double>

result_type Infinity::Engine::PiecewiseConstantDistribution< RealType >::max ( ) const

inline

Gets the maximum value that can be generated.

◆ min()

template<typename RealType = double>

result_type Infinity::Engine::PiecewiseConstantDistribution< RealType >::min ( ) const

inline

Gets the minimum value that can be generated.

◆ operator()() [1/2]

template<typename RealType = double>

template<typename Generator >

result_type Infinity::Engine::PiecewiseConstantDistribution< RealType >::operator() ( Generator & g )

inline

Generates the next random value using stored parameters.

Template Parameters

Generator The random number generator type (e.g., PRNG)

Parameters

g	The random number generator

Returns: A random value according to the piecewise constant distribution

◆ operator()() [2/2]

template<typename RealType = double>

template<typename Generator >

result_type Infinity::Engine::PiecewiseConstantDistribution< RealType >::operator()	(	Generator &	g,
		const param_type &	param
	)

inline

Generates the next random value using provided parameters.

Uses a two-step process:

Select an interval based on cumulative probabilities (binary search)
Generate uniform value within the selected interval

This ensures the density within each interval is constant while different intervals can have different probabilities of selection.

Template Parameters

Generator The random number generator type (e.g., PRNG)

Parameters

g	The random number generator
param	The distribution parameters to use for this generation

Returns: A random value from the piecewise constant distribution

◆ param() [1/2]

template<typename RealType = double>

param_type Infinity::Engine::PiecewiseConstantDistribution< RealType >::param ( ) const

inline

Gets the current parameter set.

◆ param() [2/2]

template<typename RealType = double>

void Infinity::Engine::PiecewiseConstantDistribution< RealType >::param ( const param_type & param )

inline

Sets new parameters for the distribution.

◆ reset()

template<typename RealType = double>

void Infinity::Engine::PiecewiseConstantDistribution< RealType >::reset ( )

inline

Resets the distribution state.

No-op for piecewise constant distribution as it maintains no internal state.

Friends And Related Symbol Documentation

◆ operator!=

template<typename RealType = double>

bool operator!=	(	const PiecewiseConstantDistribution< RealType > &	lhs,
		const PiecewiseConstantDistribution< RealType > &	rhs
	)

friend

◆ operator==

template<typename RealType = double>

bool operator==	(	const PiecewiseConstantDistribution< RealType > &	lhs,
		const PiecewiseConstantDistribution< RealType > &	rhs
	)

friend

Classes

Public Types

Public Member Functions

Friends

Detailed Description

Member Typedef Documentation

◆ result_type

Constructor & Destructor Documentation

◆ PiecewiseConstantDistribution() [1/5]

◆ PiecewiseConstantDistribution() [2/5]

◆ PiecewiseConstantDistribution() [3/5]

◆ PiecewiseConstantDistribution() [4/5]

◆ PiecewiseConstantDistribution() [5/5]

Member Function Documentation

◆ densities()

◆ intervals()

◆ max()

◆ min()

◆ operator()() [1/2]

◆ operator()() [2/2]

◆ param() [1/2]

◆ param() [2/2]

◆ reset()

Friends And Related Symbol Documentation

◆ operator!=

◆ operator==