I am a long time Rhino user and developer and have successfully used the OpenNurbs sdk a couple of years ago in VS2008. I recently upgraded to VS2013 and need to extract some curve information from a Rhino 5 (fully patched) model.
I installed the Rhino3dmIO Nuget package as per https://github.com/mcneel/rhinocommon/wiki/Rhino3dmIO-Toolkit-(OpenNURBS-build) and was able to open my 3dm file, iterate through all the objects and find the curve I was looking for. However when I try to call curve.Length() I get
System.EntryPointNotFoundException was unhandled
_message=Unable to find an entry point named ‘ON_Curve_GetLength’ in DLL ‘rhino3dmio_native’.
Message=Unable to find an entry point named ‘ON_Curve_GetLength’ in DLL ‘rhino3dmio_native’.
at UnsafeNativeMethods.ON_Curve_GetLength(IntPtr pCurve, Double& length, Double fractional_tol, Interval sub_domain, Boolean ignoreSubDomain)
at Rhino.Geometry.Curve.GetLength(Double fractionalTolerance)