text: #include "scalar_constants.hpp"
  
  namespace glm
  {
  	template<typename T, qualifier Q>
  	GLM_FUNC_QUALIFIER T angle(qua<T, Q> const& x)
  	{
  		if (abs(x.w) > cos_one_over_two<T>())
  		{
  			return asin(sqrt(x.x * x.x + x.y * x.y + x.z * x.z)) * static_cast<T>(2);
  		}
  
  		return acos(x.w) * static_cast<T>(2);
  	}
  
  	template<typename T, qualifier Q>
  	GLM_FUNC_QUALIFIER vec<3, T, Q> axis(qua<T, Q> const& x)
  	{
  		T const tmp1 = static_cast<T>(1) - x.w * x.w;
  		if(tmp1 <= static_cast<T>(0))
  			return vec<3, T, Q>(0, 0, 1);
  		T const tmp2 = static_cast<T>(1) / sqrt(tmp1);
  		return vec<3, T, Q>(x.x * tmp2, x.y * tmp2, x.z * tmp2);
  	}
  
  	template<typename T, qualifier Q>
  	GLM_FUNC_QUALIFIER qua<T, Q> angleAxis(T const& angle, vec<3, T, Q> const& v)
  	{
  		T const a(angle);
  		T const s = glm::sin(a * static_cast<T>(0.5));
  
  		return qua<T, Q>(glm::cos(a * static_cast<T>(0.5)), v * s);
  	}
  }//namespace glm
  