osgEarth::Random Class Reference

List of all members.

Public Types
enum	Method { METHOD_FAST }
Public Member Functions
	Random (Method method=METHOD_FAST)
	Random (unsigned seed, Method method=METHOD_FAST)
	Random (const Random &rhs)
void	reset ()
unsigned	next (unsigned mod)
double	next ()
Private Attributes
Method	_method
unsigned	_seed
unsigned	_next

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Detailed Description

Psuedo random number generator. Results are guaranteed to be consistent across machines given the same seed value.

Definition at line 30 of file Random.

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Member Enumeration Documentation

enum osgEarth::Random::Method

Enumerator:

METHOD_FAST

Definition at line 33 of file Random.

        {
            METHOD_FAST        // not great, but super-fast and cheap.
        };

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Constructor & Destructor Documentation

Random::Random

(

Random::Method

method = METHOD_FAST

)

Constructs a new random number generator. It is seeded with the system clock.

Parameters:

method

RNG method to use

Definition at line 41 of file Random.cpp.

                                    :
_method( method ),
_seed  ( (unsigned)::time(0L) )
{
    _next = _seed;
}

Random::Random	(	unsigned	seed,
		Random::Method	method = METHOD_FAST
	)

Constucts a new random number generator with a user-specified seed. The results are guaranteed to be globally consistent.

Parameters:

seed	RNG seed value
method	RNG method to use

Definition at line 48 of file Random.cpp.

                                                   :
_method( method ),
_seed  ( seed == 0 ? (unsigned)::time(0L) : seed ) // seed=0 => time-based
{
    _next = _seed;
}

Random::Random

(

const Random &

rhs

)

Copy constructor.

Definition at line 55 of file Random.cpp.

                                  :
_method( rhs._method ),
_seed  ( rhs._seed ),
_next  ( rhs._next )
{
    //nop
}

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Member Function Documentation

unsigned Random::next

(

unsigned

mod

)

Gets the next random number as an unsigned int.

Parameters:

mod	Modulus value. The result will fall within the range [0..mod)

Definition at line 70 of file Random.cpp.

{
    if ( _method == METHOD_FAST )
    {
        fast_rand( _next );
    }    
    return mod == UINT_MAX ? _next : _next % mod;
}

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double Random::next

(

)

Gets the next random number as a double in the range [0..1].

Definition at line 80 of file Random.cpp.

{
    return (double)next(UINT_MAX) / (double)UINT_MAX;
}

void Random::reset

(

)

Resets the PRNG to its initial state (initial seed).

Definition at line 64 of file Random.cpp.

{
    _next = _seed;
}

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Member Data Documentation

Method osgEarth::Random::_method [private]

Definition at line 76 of file Random.

unsigned osgEarth::Random::_next [private]

Definition at line 78 of file Random.

unsigned osgEarth::Random::_seed [private]

Definition at line 77 of file Random.

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

• /home/cube/sources/osgearth/src/osgEarth/Random
• /home/cube/sources/osgearth/src/osgEarth/Random.cpp