Import STEP CAD files (.step/.stp) in the editor and at runtime. Pure C#, no native plugins: exact NURBS tessellation, assemblies, colors and units – ready-to-use prefabs.Bring CAD models into Unity – from SolidWorks, CATIA or any other CAD system that exports STEP.Drag a .step or .stp file into your project just as you would with an fbx. Complete assembly structure, names, colors and correctly scaled, watertight meshes. Or load STEP files at runtime with a single line of code. Tested on PC, Android and WebGL - should work for any other platform, too.100% C#, NO NATIVE PLUGINSSTEP Importer is written entirely in C#. No native DLLs, no external CAD kernel and no third-party licenses – it is not tied to Windows and is easy to ship with your application. Full source code is included.HIGH-QUALITY TESSELLATIONThe exact CAD geometry (B-rep) is converted to triangles with adjustable quality.EDITOR IMPORT- Quality presets (Low to Very High) or custom tolerances- Import report with statistics and warnings- Extract and remap materials, generate lightmap UVs, add mesh colliders- Progress bar with cancel for large filesRUNTIME LOADING- GameObject model = await StepLoader.LoadAsync(path);- Loading from files, memory or URLs, with progress and cancellation- Reading and tessellation run on background threads, objects are created over several frames – your app stays responsive- Destroying the model frees all its meshes and materials automatically- STEP Model Loader component: load files without writing codeVALIDATED WITH REAL CAD DATATested with the public NIST CAD test models (AP203 and AP242 exports from CATIA, NX, Creo and SolidWorks) and real-world parts, assemblies and city models.Ideal for digital twins, industrial and product visualization, configurators, AR/VR training, simulation and engineering tools.Note: STEP Importer reads STEP files. Native CAD formats (e.g. .sldprt, .catpart) can be exported as STEP from the CAD system. Product manufacturing information (dimensions, tolerances) is not displayed.- File format: STEP (ISO 10303-21), .step / .stp- Schemas: AP203, AP214 (automotive design), AP242 editions 1–3- Surfaces: plane, cylinder, cone, sphere, torus, B-spline / NURBS (rational, periodic), surface of revolution, surface of linear extrusion, offset surface- Curves: line, circle, ellipse, B-spline / NURBS, polyline, trimmed, surface and seam curves- Topology: manifold solids, solids with voids, faceted B-reps, shell-based surface models- AP242 tessellated geometry (triangulated faces, strips, fans)- Assemblies with nested sub-assemblies, instance names and transforms; repeated parts share meshes- Colors and transparency per solid, shell or face; hidden geometry and layers are respected- Automatic unit conversion (mm, cm, m, inch, …) to meters and Z-up to Y-up conversion- Tessellation: quality presets or custom chord / angle tolerance, watertight meshes, exact normals, adaptive refinement, multithreaded- Editor: ScriptedImporter, inspector with import report, material extraction / remapping, lightmap UVs, mesh colliders, read/write option- Runtime API: StepLoader (sync, async, URL), STEP Model Loader component, StepModelInfo (statistics, warnings), progress, cancellation, automatic cleanup- Engine-independent, thread-safe reader API (StepReader) for custom pipelines- Performance example: 20 MB STEP file with 7,500 faces imported in under 2 seconds (desktop PC)- No native code, no external dependencies; full C# source code with assembly definitions (namespace CHAssets.StepImporter)- Includes documentation and a runtime loading sample scene- Tested with Unity 2022.3 to Unity 6 on PC, WebGL, and Android - other Platforms should work, tooAI (LLMs) assisted during research, development and documentation.
