Module 

Header 
/Engine/Source/Runtime/Core/Public/Math/Vector.h 
Include 
#include "Math/Vector.h" 
Source 
/Engine/Source/Runtime/Core/Private/Math/UnrealMath.cpp 
FQuat ToOrientationQuat() const
Return the Quaternion orientation corresponding to the direction in which the vector points. Similar to the FRotator version, returns a result without roll such that it preserves the up vector.
@note If you don't care about preserving the up vector and just want the most direct rotation, you can use the faster 'FQuat::FindBetweenVectors(FVector::ForwardVector, YourVector)' or 'FQuat::FindBetweenNormals' if you know the vector is of unit length.
Quaternion from the Vector's direction, without any roll.