glm/glm/gtc/random.inl

//////////////////////////////////////////////////////////////////////////////////
// OpenGL Mathematics Copyright (c) 2005 - 2011 G-Truc Creation (www.g-truc.net)
//////////////////////////////////////////////////////////////////////////////////
// Created : 2011-09-19
// Updated : 2011-09-19
// Licence : This source is under MIT License
// File    : glm/gtc/random.inl
//////////////////////////////////////////////////////////////////////////////////

#include <ctime>
#include <cassert>

namespace glm{

template <> 
GLM_FUNC_QUALIFIER glm::half linearRand
(
	glm::half const & Min, 
	glm::half const & Max
)
{
	return glm::half(float(std::rand()) / float(RAND_MAX) * (float(Max) - float(Min)) + float(Min));
}
	
template <> 
GLM_FUNC_QUALIFIER float linearRand
(
	float const & Min, 
	float const & Max
)
{
	return float(std::rand()) / float(RAND_MAX) * (Max - Min) + Min;
}
	
template <> 
GLM_FUNC_QUALIFIER double linearRand
(
	double const & Min, 
	double const & Max
)
{
	return double(std::rand()) / double(RAND_MAX) * (Max - Min) + Min;
}
	
template <typename T>
GLM_FUNC_QUALIFIER detail::tvec2<T> linearRand
(
	detail::tvec2<T> const & Min, 
	detail::tvec2<T> const & Max
)
{
	return detail::tvec2<T>(
		linearRand(Min.x, Max.x),
		linearRand(Min.y, Max.y));
}
	
template <typename T>
GLM_FUNC_QUALIFIER detail::tvec3<T> linearRand
(
	detail::tvec3<T> const & Min, 
	detail::tvec3<T> const & Max
)
{
	return detail::tvec3<T>(
		linearRand(Min.x, Max.x),
		linearRand(Min.y, Max.y),
		linearRand(Min.z, Max.z));
}

template <typename T>
GLM_FUNC_QUALIFIER detail::tvec4<T> linearRand
(
	detail::tvec4<T> const & Min, 
	detail::tvec4<T> const & Max
)
{
	return detail::tvec4<T>(
		linearRand(Min.x, Max.x),
		linearRand(Min.y, Max.y),
		linearRand(Min.z, Max.z),
		linearRand(Min.w, Max.w));
}

template <typename genType> 
GLM_FUNC_QUALIFIER genType gaussRand
(
	genType const & Mean,	
	genType const & Deviation
)
{
    genType w, x1, x2;
	
    do
    {
        x1 = linearRand(genType(-1), genType(1));
        x2 = linearRand(genType(-1), genType(1));
		
        w = x1 * x1 + x2 * x2;
    } while(w > genType(1));
	
    return x2 * Deviation * Deviation * sqrt((genType(-2) * log(w)) / w) + Mean;
}

template <typename T>
GLM_FUNC_QUALIFIER detail::tvec2<T> gaussRand
(
	detail::tvec2<T> const & Mean, 
	detail::tvec2<T> const & Deviation
)
{
	return detail::tvec2<T>(
		gaussRand(Mean.x, Deviation.x),
		gaussRand(Mean.y, Deviation.y));
}
	
template <typename T>
GLM_FUNC_QUALIFIER detail::tvec3<T> gaussRand
(
	detail::tvec3<T> const & Mean, 
	detail::tvec3<T> const & Deviation
)
{
	return detail::tvec3<T>(
		gaussRand(Mean.x, Deviation.x),
		gaussRand(Mean.y, Deviation.y),
		gaussRand(Mean.z, Deviation.z));
}
	
template <typename T>
GLM_FUNC_QUALIFIER detail::tvec4<T> gaussRand
(
	detail::tvec4<T> const & Mean, 
	detail::tvec4<T> const & Deviation
)
{
	return detail::tvec4<T>(
		gaussRand(Mean.x, Deviation.x),
		gaussRand(Mean.y, Deviation.y),
		gaussRand(Mean.z, Deviation.z),
		gaussRand(Mean.w, Deviation.w));
}
	
template <typename T>
GLM_FUNC_QUALIFIER detail::tvec2<T> diskRand
(
	T const & Radius
)
{		
	detail::tvec2<T> Result(T(0));
	T LenRadius(T(0));
		
	do
	{
		Result = linearRand(detail::tvec2<T>(-Radius), detail::tvec2<T>(Radius));
		LenRadius = length(Result);
	}
	while(LenRadius > Radius);
		
	return Result;
}
	
template <typename T>
GLM_FUNC_QUALIFIER detail::tvec3<T> ballRand
(
	T const & Radius
)
{		
	detail::tvec3<T> Result(T(0));
	T LenRadius(T(0));
		
	do
	{
		Result = linearRand(detail::tvec3<T>(-Radius), detail::tvec3<T>(Radius));
		LenRadius = length(Result);
	}
	while(LenRadius > Radius);
		
	return Result;
}
	
template <typename T> 
GLM_FUNC_QUALIFIER detail::tvec2<T> circularRand
(
	T const & Radius
)
{
	T a = linearRand(T(0), T(6.283185307179586476925286766559f));
	return detail::tvec2<T>(cos(a), sin(a)) * Radius;		
}
	
template <typename T> 
GLM_FUNC_QUALIFIER detail::tvec3<T> sphericalRand
(
	T const & Radius
)
{
	T z = linearRand(T(-1), T(1));
	T a = linearRand(T(0), T(6.283185307179586476925286766559f));
	
	T r = sqrt(T(1) - z * z);
	
	T x = r * cos(a);
	T y = r * sin(a);
	
	return detail::tvec3<T>(x, y, z) * Radius;	
}

}//namespace glm