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Hey HN,

I’ve been building BREP.io, a parametric CAD system that runs entirely in the browser.

https://BREP.io

https://github.com/mmiscool/BREP.io

The core idea is applying a B-Rep-style topology layer on top of a 3D mesh representation.

Instead of treating the mesh as the model itself, the mesh is just the geometric carrier. On top of that, there’s an explicit topology layer that tracks: - Faces as structured surface regions - Edges as shared boundaries - Vertex connectivity and adjacency - Ownership relationships between elements

The mesh handles rendering and geometric evaluation. The topology layer handles structure.

This separation makes it possible to: - Perform parametric edits against stable topological entities - Run boolean operations while preserving structural relationships - Maintain a consistent model even as geometry changes

It’s been an interesting exercise in bridging two worlds: the performance and simplicity of mesh engines, and the structured consistency of boundary representation modeling.

If you’re into CAD kernels, computational geometry, or browser-based engineering tools, I’d love feedback especially on architectural tradeoffs when layering topology over meshes.

Happy to answer questions about how it works.

- mmiscool