Surface normal


I found two ways to get the normal vector of a surface. One is working from the sample library however I do not understand the second one from the forum. Clement refers to “Normal.Z” however I cannot find in the Rhino Common docs.

From forum:

sample: IronPython

You mean these? -->

Yess, thank you!

Nathan, can you help me how I can set multiple type of objects in the filter? I would like to select Surface and Brep as well.

gs.GeometryFilter = Rhino.DocObjects.ObjectType.Surface (I put 24 but got syntax error)

You can OR them together like here:

Thank you,

another thing that I already have code to get the surface and I need to reference.
I have found a GetOneObject with Objref. Can I use that class and connect with NormalAt method?