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