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Fix singularity in quaternion to euler angle roll conversion#1019

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Merged
christophe-lunarg merged 1 commit into from
Nov 21, 2020
Merged

Fix singularity in quaternion to euler angle roll conversion #1019

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8 changes: 7 additions & 1 deletion glm/gtc/quaternion.inl
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,13 @@ namespace glm
template<typename T, qualifier Q>
GLM_FUNC_QUALIFIER T roll(qua<T, Q> const& q)
{
return static_cast<T>(atan(static_cast<T>(2) * (q.x * q.y + q.w * q.z), q.w * q.w + q.x * q.x - q.y * q.y - q.z * q.z));
T const y = static_cast<T>(2) * (q.x * q.y + q.w * q.z);
T const x = q.w * q.w + q.x * q.x - q.y * q.y - q.z * q.z;

if(all(equal(vec<2, T, Q>(x, y), vec<2, T, Q>(0), epsilon<T>()))) //avoid atan2(0,0) - handle singularity - Matiis
return static_cast<T>(0);

return static_cast<T>(atan(y, x));
}

template<typename T, qualifier Q>
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