public FQuat(FVector Axis, float AngleRad)
{
float half_a = 0.5f * AngleRad;
float s, c;
FMath.SinCos(out s, out c, half_a);
X = s * Axis.X;
Y = s * Axis.Y;
Z = s * Axis.Z;
W = c;
//DiagnosticCheckNaN();
}