NVIDIA Opens USD BRep's CAD Kernel to Developers Under Apache 2.0
NVIDIA open sourced its NURBS boundary-representation CAD kernel under Apache 2.0, giving developers an exact-geometry solid modeling library that reads and writes OpenUSD natively.
- NVIDIA open sourced USD BRep, a NURBS boundary-representation solid modeling kernel, under Apache 2.0.
- Ships SMLib, a mature kernel based on the Piegl and Tiller NLib NURBS library used in commercial CAD for decades.
- Covers booleans, fillets, chamfers, shells, sweeps, intersectors, mass properties, and healing in C++ and Python.
- Native OpenUSD import and export plus STEP, IGES, and JT via bundled OpenCASCADE conversion.
- Pitched at AI-to-CAD: exact geometry fed to neural nets instead of triangle meshes or opaque feature trees.
- A Rust port called solidcore appeared within a day of release.
NVIDIA releases its SMLib CAD kernel under Apache 2.0
NVIDIA has published USD BRep, an Apache 2.0 project that packages the SMLib solid-modeling kernel with native OpenUSD support. The standalone C++ and Python library gives developers source access to NURBS-based boundary-representation modeling previously used in commercial CAD products.
The engine under the model
A boundary-representation kernel describes a solid through connected faces, edges, and vertices. NURBS equations define curved surfaces precisely, while the kernel maintains the topology connecting them. It also performs operations such as cutting holes, joining bodies, rounding edges, offsetting faces, and hollowing solids.
Commercial CAD systems commonly rely on proprietary kernels such as Siemens Parasolid and Dassault Systèmes ACIS. Those products require commercial agreements and restrict access to their implementations. USD BRep adds a permissively licensed option that teams can embed, inspect, and modify.
SMLib builds on NLib, a NURBS curve and surface library developed by Wayne Tiller and Les Piegl, co-authors of The NURBS Book. NVIDIA’s project documentation describes SMLib as a kernel for integration into other 3D applications, with support for exact surfaces, polygonal geometry, and OpenUSD data exchange.
Inside SMLib’s operation set
The public C++ headers expose a broad modeling API. Functions in SmApiBrep.h include SmApiBoolean, SmApiFilletEdges, SmApiVariableRadiusFillet, SmApiShellBrepFull, and SmApiStitch, alongside non-manifold sweep and Boolean variants.
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