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Added low precision specializations of inversesqrt

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This commit is contained in:
Christophe Riccio 2013-09-15 13:36:05 +02:00
parent 741756f17d
commit 4bd84e1a0c
1 changed files with 48 additions and 0 deletions
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48
glm/core/func_exponential.inl
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@ -153,4 +153,52 @@ namespace _detail
VECTORIZE_VEC(inversesqrt)
template <>
GLM_FUNC_QUALIFIER lowp_vec1 inversesqrt(lowp_vec1 const & v)
{
float tmp(v.x);
float xhalf(0.5f * tmp);
uint i = *reinterpret_cast<uint*>(const_cast<lowp_vec1*>(&v));
i = 0x5f375a86 - (i >> 1);
tmp = *reinterpret_cast<float*>(i);
tmp = tmp * (1.5f - xhalf * tmp * tmp);
return lowp_vec1(tmp);
}
template <>
GLM_FUNC_QUALIFIER lowp_vec2 inversesqrt(lowp_vec2 const & v)
{
lowp_vec2 tmp(v);
lowp_vec2 xhalf(0.5f * tmp);
lowp_uvec2 i = *reinterpret_cast<lowp_uvec2*>(const_cast<lowp_vec2*>(&v));
i = lowp_uvec2(0x5f375a86) - (i >> lowp_uvec2(1));
tmp = *reinterpret_cast<lowp_vec2*>(&i);
tmp = tmp * (1.5f - xhalf * tmp * tmp);
return tmp;
}
template <>
GLM_FUNC_QUALIFIER lowp_vec3 inversesqrt(lowp_vec3 const & v)
{
lowp_vec3 tmp(v);
lowp_vec3 xhalf(0.5f * tmp);
lowp_uvec3 i = *reinterpret_cast<lowp_uvec3*>(const_cast<lowp_vec3*>(&v));
i = lowp_uvec3(0x5f375a86) - (i >> lowp_uvec3(1));
tmp = *reinterpret_cast<lowp_vec3*>(&i);
tmp = tmp * (1.5f - xhalf * tmp * tmp);
return tmp;
}
template <>
GLM_FUNC_QUALIFIER lowp_vec4 inversesqrt(lowp_vec4 const & v)
{
lowp_vec4 tmp(v);
lowp_vec4 xhalf(0.5f * tmp);
lowp_uvec4 i = *reinterpret_cast<lowp_uvec4*>(const_cast<lowp_vec4*>(&v));
i = lowp_uvec4(0x5f375a86) - (i >> lowp_uvec4(1));
tmp = *reinterpret_cast<lowp_vec4*>(&i);
tmp = tmp * (1.5f - xhalf * tmp * tmp);
return tmp;
}
}//namespace glm