/// Get the link coordinate system, expressed relative to Body2 (spherical side).
/// This represents the 'main' reference of the link: reaction forces
/// and reaction torques are reported in this coordinate system.
public override ChCoordsys GetLinkRelativeCoords()
{
ChVector pos1 = Body2.TransformPointParentToLocal(Body1.TransformPointLocalToParent(m_pos1));
ChMatrix33 <double> A = new ChMatrix33 <double>(0);
ChVector u = (m_pos2 - pos1).GetNormalized();
ChVector w = Body2.TransformDirectionParentToLocal(Body1.TransformDirectionLocalToParent(m_dir1));
ChVector v = ChVector.Vcross(w, u);
A.Set_A_axis(u, v, w);
return(new ChCoordsys(pos1, A.Get_A_quaternion()));
}