Isoform

Research spike for an AI-native, human-usable parametric CAD geometry core.

The question: can an implicit (F-rep/CSG) core keep stable, CAD-meaningful references to faces, edges and vertices while producing exact output, and does it do better at this than a B-rep kernel? See docs/research-plan.md for the hypotheses, the edit suite and the results.

Try it: the playground runs the kernel in your browser (WebAssembly, one thread; the chat panel needs the native server, see below).

Layout

Project	What
Isoform.Document	Feature graph, canonical text format (git-diffable), content hash, edits as data
Isoform.Geometry	Analytic surfaces (plane, cylinder, sphere, cone, torus), CSG fields with ownership, swept profiles, exact rolling-ball fillets, smooth blends
Isoform.Meshing	Adaptive, feature-preserving dual contouring with a resolution guarantee
Isoform.Modeling	Regeneration, topology, references, diagnostics: the backend-neutral API
Isoform.Build	Build methods: a design made of exact plates and tubes, with STEP, DXF, cut list, bill of materials and a certified verification report (the demo)
Isoform.Occt	OCCT B-rep baseline behind the same API
Isoform.Playground	The kernel in the browser (WebAssembly): document editor and 3D view
Isoform.Server	The playground with the kernel running natively: a localhost server, the page's worker protocol over WebSocket, and the chat panel's Claude agent
native/Isoform.Occt	Small C ABI over OpenCASCADE used by Isoform.Occt

Features

Block, hole, plane cut; extrude and revolve of line-and-arc sketches; linear, circular and mirror patterns; fillet and chamfer (also on faces shared with earlier fillets, on swept edges and after a shell); shell; offset; smooth join and cut. Every face is named after the feature that made it, and keeps that name through edits.

Build and test

Requires the .NET 10 SDK.

dotnet test tests/Isoform.Tests        # core: needs nothing else

The OCCT baseline is optional. It needs an OpenCASCADE 8.0 build, CMake ≥ 3.21 and a C++17 compiler:

# installed OCCT (folder with OpenCASCADEConfig.cmake)
cmake -S native/Isoform.Occt -B native/build -DOpenCASCADE_DIR=<occt-install>/cmake
# or a plain OCCT build folder (inc/ and win64/vc14/{lib,bin})
cmake -S native/Isoform.Occt -B native/build -DOCCT_ROOT=<occt-build>

cmake --build native/build --config Release
dotnet test tests/Isoform.Occt.Tests

Playground

The kernel compiled to WebAssembly, running in the browser: edit the document, see the part regenerate, hover a face for its name, click two faces to get the edge to fillet, read the diagnostics.

dotnet run --project src/Isoform.Playground     # http://localhost:5240, interpreted: fine for small parts

For a faster build, compiled ahead of time (needs dotnet workload install wasm-tools once):

dotnet publish src/Isoform.Playground -c Release -o out/playground
python -m http.server 8137 -d out/playground/wwwroot   # or any static file server

The page needs no network: three.js r160 is vendored in wwwroot/vendor/three. In the browser the kernel runs on one thread, so it is several times slower than on the desktop.

For the kernel at desktop speed, on all cores, run the page from the native server:

dotnet run -c Release --project src/Isoform.Server  # http://localhost:5250
dotnet run -c Release --project src/Isoform.Server -- --port 5260 --root <published wwwroot>

It serves the published playground (out/playground/wwwroot, else the page's sources) on localhost only, and runs the kernel natively behind a WebSocket at /kernel, a session per connection, speaking the same protocol as the page's workers. The page uses it when the server served it, or when ?kernel=ws://localhost:5250/kernel points at one (a page from another origin needs --allow-origin <origin>: other sites cannot reach the kernel); the status line says native or wasm. Without a server, or with ?kernel=wasm, the page runs the kernel in WebAssembly as before, so a shared link works from any static host.

With the server, the Chat panel lets you ask Claude for changes ("make the plate 120 long"): the server runs Claude (claude-opus-5-5, through the official Anthropic SDK) with the MCP tool set on the page's document, and its edits come back as one history entry, shown in the agent view and undone like any other. The API key is read from the server's environment only; the page never sees it:

export ANTHROPIC_API_KEY=...                       # PowerShell: $env:ANTHROPIC_API_KEY = "..."
dotnet run -c Release --project src/Isoform.Server

Without a key the server says so at start and the chat answers that it has none; in WebAssembly the panel is inert.

About

Made by Bas Automation Services: Autodesk Inventor add-ins and CAD automation from Rotterdam.

Licence

MPL-2.0. OpenCASCADE is LGPL-2.1 with an exception and is linked dynamically. The vendored three.js is MIT (its licence).