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Clamp function
From Unreal Wiki, The Unreal Engine Documentation Site
Clamp is math function provided by the Object(RTNP, U1, UT, U2, U2XMP, UE2Runtime, UT2003, UT2004, UDK, UT3) class.
Limits V to the interval of [A, B]. Exactly speaking, A will be returned if V is smaller than A, B will be returned if V is larger than B, otherwise V is returned.
This also applies if A is larger than B. So if V is larger than B, but smaller than A, the value of A is returned even though V is actually between the two values.