Mesh.IsPointInside() persistent bug

I’m not sure what your mesh looks like. The algorithm simply creates a line from the test point to a point know to be outside of the mesh. An intersection is run on this line with the mesh and if the number of intersections is an odd number, true is returned. I’m sure there is a more robust approach, but that is what we currently have implemented.

You could try the same test with the MeshLine intersect routine in RhinoCommon.