Making our own surface, but result is an invalid surface?

Rhino Developer
1

Hi,
We have been doing some work with a RhinoCommon plugin to try and make this shape with a single Nurbs surface.

And as far as I can tell we are making it correctly…
But when it is added into Rhino it is reporting as an Invalid polysurface, and we are not sure why.
We are a little unclear about if we have the Knots in the V direction correct.
Or if it is something to do with the fact we have 2 location (2,0,z) and (-2,0,z) where there are a number of points on top of each other.

barset.3dm (24.4 KB)

Any guidance here would be greatly appreciated.

2

Please change the category to “Developer” as you are working with a RhinoCommon plug-in, not the open-source 3dm reading/writing library openNURBS.

Secondly, it would be nice if you could share some code. Also, before adding any geometry you can do the following:

GeometryBase geo; // any geometry, including Surface, NurbsSurface, etc.
String error;
if (!geo.IsValidWithLog(out error))
    RhinoApp.WriteLine("Surface invalid because: {0}", error);
else
    doc.Add(geo);
3

ProngBar.zip (6.7 KB)

Hi,
So here is a simplified version of our plugin that is making this geometry.
So the IsValidWithLog is actually returning true (Valid)
But the geometry in Rhino is showing as invalid.

4

Gordon,

Here is the error repported by openNURBS:

ON_Brep.m_T[7].m_type = ON_BrepTrim::seam but m_iso is not N/E/W/S_iso.

Does this help?