uncad-model

The neutral entity model for 2D CAD drawings: what a drawing is once it has been taken out of its file format.

Every entity carries a reference ID, a provenance and a confidence — so that anything built on the model can say where a value came from and how far it can be trusted, including "unknown".

This crate is pure data: types and serialization, plus the coordinate arithmetic the format defines on an entity's own fields, which every consumer needs alike -- the placement an INSERT applies to its block (Affine2), the coordinate system an entity is written in (Ocs), the arc a polyline vertex's bulge describes (BulgeArc), the point at a parameter on an ellipse or a NURBS curve (EllipseEntity::point_at, Nurbs), and how far an arc or an ellipse runs (ArcEntity::sweep, EllipseEntity::sweep) -- the unit a $INSUNITS code names (Units), and the wireframe of a 3DSOLID's or a REGION's ACIS body from its SAT text or its SAB bytes (acis::wireframe, acis::wireframe_sab). It reads no file, renders nothing, and has no native dependencies.

Dependencies

The dependency tree is permissive-only (MIT / Apache-2.0 / BSD). This crate depends on no parser, no renderer and no native code, so anything that needs only to describe a drawing can depend on it alone.

Status

0.x. The crate provides:

• Entities — Entity and one struct per kind, each carrying a reference ID, a provenance and a confidence, with a three-state Ref for every reference and plain Point2D / Point3D.
• Tables — Tables: layers, block definitions, dimension styles, mline styles, and the layouts with their plot settings.
• Placement — Affine2, the transform a block reference applies to its block, composed across nested references; InsertEntity::world_transform places a mirror copy's block too.
• Palette and diagnostics — the ACI colour table and the reader diagnostics a drawing carries.
• Serialization — CadDatabase::to_json, a direct serde form that round-trips.

The design rules are in docs/principles.md.

golden/ is a test-only crate (not published): synthetic drawing specs, a DXF writer for them, and property checks, usable as a dev-dependency.

License

MIT