Returns in *pPointer the base pointer of the subresource of the mapped Direct3D resource pResource which corresponds to subResource. The value set in pPointer may change every time that pResource is mapped.
If pResource is of type ID3D10Buffer then subResource must be 0. If pResource is of any other type, then the value of subResource must come from the subresource calculation in D3D10CalcSubResource().