namespace glm { template<typename T, qualifier Q> GLM_FUNC_QUALIFIER T angle(qua<T, Q> const& x) { 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