Hi Sam,

Indeed Rhino3dmIO is open-source, but that supports only reading and writing of the open 3dm file format and “simple” geometry operations that are part of the OpenNURBS library. The more advanced geometry operations, like `Mesh.CreateFromBrep`

are only supported *inside* Rhino, because this uses the closed-source part. These more advanced operations also include brep and mesh booleans, curve intersections, closest-point finding, etc. etc.

So yes, you can use the 3dm file format and the whole geometry data structure + simple operations that comes with Rhino3dmIO, but you can’t use the more advanced functions. Think of the McNeel perspective: if they would open-source Rhino completely, another company could use their algorithms for these advanced functions and Rhino sales would most probably be affected. These algorithms are typically developed and fine-tuned over years.