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///////////////////////////////////////////////////////////////////////////////////////////////////
// OpenGL Mathematics Copyright (c) 2005 - 2013 G-Truc Creation (www.g-truc.net)
///////////////////////////////////////////////////////////////////////////////////////////////////
// Created : 2006-01-04
// Updated : 2011-10-14
// Licence : This source is under MIT License
// File : glm/gtx/fast_square_root.inl
///////////////////////////////////////////////////////////////////////////////////////////////////
namespace glm
{
// fastSqrt
template <typename genType>
GLM_FUNC_QUALIFIER genType fastSqrt
(
genType const & x
)
{
GLM_STATIC_ASSERT(detail::type<genType>::is_float, "'fastSqrt' only accept floating-point input");
return genType(1) / fastInverseSqrt(x);
}
VECTORIZE_VEC(fastSqrt)
// fastInversesqrt
template <typename genType>
GLM_FUNC_QUALIFIER genType fastInverseSqrt
(
genType const & x
)
{
genType tmp = x;
float xhalf = 0.5f * float(tmp);
uint i = *(uint*)&x;
i = 0x5f375a86 - (i >> 1);
//x = *(float*)&i;
//x = *((float*)(char*)&i);
tmp = detail::uif(i).f;
tmp = tmp * (1.5f - xhalf * tmp * tmp);
return genType(tmp);
}
VECTORIZE_VEC(fastInverseSqrt)
// fastLength
template <typename genType>
GLM_FUNC_QUALIFIER genType fastLength
(
genType const & x
)
{
return abs(x);
}
template <typename valType>
GLM_FUNC_QUALIFIER valType fastLength
(
detail::tvec2<valType> const & x
)
{
valType sqr = x.x * x.x + x.y * x.y;
return fastSqrt(sqr);
}
template <typename valType>
GLM_FUNC_QUALIFIER valType fastLength
(
detail::tvec3<valType> const & x
)
{
valType sqr = x.x * x.x + x.y * x.y + x.z * x.z;
return fastSqrt(sqr);
}
template <typename valType>
GLM_FUNC_QUALIFIER valType fastLength
(
detail::tvec4<valType> const & x
)
{
valType sqr = x.x * x.x + x.y * x.y + x.z * x.z + x.w * x.w;
return fastSqrt(sqr);
}
// fastDistance
template <typename genType>
GLM_FUNC_QUALIFIER genType fastDistance
(
genType const & x,
genType const & y
)
{
return fastLength(y - x);
}
// fastNormalize
template <typename genType>
GLM_FUNC_QUALIFIER genType fastNormalize
(
genType const & x
)
{
return x > genType(0) ? genType(1) : -genType(1);
}
template <typename valType>
GLM_FUNC_QUALIFIER detail::tvec2<valType> fastNormalize
(
detail::tvec2<valType> const & x
)
{
valType sqr = x.x * x.x + x.y * x.y;
return x * fastInverseSqrt(sqr);
}
template <typename valType>
GLM_FUNC_QUALIFIER detail::tvec3<valType> fastNormalize
(
detail::tvec3<valType> const & x
)
{
valType sqr = x.x * x.x + x.y * x.y + x.z * x.z;
return x * fastInverseSqrt(sqr);
}
template <typename valType>
GLM_FUNC_QUALIFIER detail::tvec4<valType> fastNormalize
(
detail::tvec4<valType> const & x
)
{
valType sqr = x.x * x.x + x.y * x.y + x.z * x.z + x.w * x.w;
return x * fastInverseSqrt(sqr);
}
}//namespace glm
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