# SudDFace surface geometry

Hello ,
with openurbs sdk ,
how I can get the nurbs_surface definition from a SubDFace , and also the nurbs curve from a SubDEdge ?

thanks
Laurent

toNUrbs command, and dupedge command

Hi @eraud,

`ON_SubD::BrepForm` is not implemented in standalone openNURBS.

– Dale

Hello Dale ,

yes , I can see into opennurbs SDK :

//virtual
bool ON_SubD::HasBrepForm() const
{
return false;
}

//virtual
ON_Brep* ON_SubD::BrepForm( ON_Brep* destination_brep) const
{
return nullptr;
}

and when I use the method ,

class ON_NurbsSurface& nurbs_surface
) const

or

class ON_BezierSurface& bezier_surface
) const

I never get the surface because I always have the same way with :

``````if ( false == qft.m_bIsCubicPatch )
return false;
``````

I try with a plane and sphere transform to SubD with rhino7

with Rhino , I can export to iges-step these subd , can you tell me if you have a function into opennurbs SDK , for getting the nurbs_surface-curve definition or not ?

thanks
Laurent

No we do not, sorry.

– Dale

Hello Dale ,

as with rhino7 , you can export to step these subd , is it possible to know the algorithm that you use for getting the nurbs definition I will implement the same way ?

thanks
Laurent