Called by the base class to enable the derived transform to fully implement surface picking.
HRESULT retVal = object.OnSurfacePick(OutPoint, ulInputIndex, InVec);
OutPoint [in, ref]
Type: const CDXDBnds
Coordinates of the point in the transform output space to use for surface picking.
ulInputIndex [out, ref]
Type: unsigned long
Index of the input that was hit.
InVec [out, ref]
Point on the input that was hit, in terms of the input coordinate space.