from Hacker News

Fncad: Cad editor, like openscad but sdf

by FeepingCreature on 6/7/25, 10:13 PM with 5 comments

• by FeepingCreature on 6/7/25, 10:13 PM

  I (Sonnet 3.7 really) made a text-based CAD editor. It's like OpenSCAD but the backing abstraction is Signed Distance Fields, so that it can represent, for instance, smooth CSG.

  The mesher is very simple; just "subdivide an octree using interval arithmetic, put a mesh around it, then fit it to the surface using the SDF gradient." The intended usecase is for 3D printing, where slight errors don't matter and you can just throw triangles at the problem.

  Performance is okay, but not great. I blame JS. ;)

  This project is AI coded, but it's not vibe-coded: I designed the core abstractions deliberately, so all design problems are my own. The website, however, is near entirely Sonnet's work.

  Source is on Github: https://github.com/fnCAD/fnCAD

• by eternityforest on 6/8/25, 5:20 AM

  Looks pretty nice! I could see this being really nice for making customizable models, if it could import and alter step files, and had something like the customizer UI in FreeCAD.