How to convert Rhino
to BREP?

Rhinoceros (typically abbreviated Rhino, or Rhino3D) is a commercial 3D computer graphics and computer-aided design (CAD) application software. Rhinoceros geometry is based on the NURBS mathematical model, which focuses on producing mathematically precise representation of curves and freeform surfaces in computer graphics (as opposed to polygon mesh-based applications).

Rhinoceros is used in processes of computer-aided design (CAD), computer-aided manufacturing (CAM), rapid prototyping, 3D printing and reverse engineering in industries including architecture, industrial design (e.g. automotive design, watercraft design), product design (e.g. jewelry design) as well as for multimedia and graphic design.

The Rhinoceros file format (.3DM) is useful for the exchange of NURBS geometry. The Rhino developers started the openNURBS Initiative to provide computer graphics software developers the tools to accurately transfer 3-D geometry between applications. An open-source toolkit, openNURBS includes the 3DM file format specification, documentation, C++ source code libraries and .NET 2.0 assemblies to read and write the file format, on supported platforms (Windows, Windows x64, Mac, and Linux).

A Brep file is a 3D model stored in the boundary representation (also known as B-rep). The Brep format is a part of Open CASCADE Technology (OCCT).

The Brep structure is made up of two major components:

• topological components such as faces, vertices, and edges;
• links between components such as surfaces, points, and curves.

It comprises three-dimensional data such as vertices, edges, wires, faces, shells, solids, compounds, edge and face triangulations, polylines on triangulations, space location, and orientation.