cad2d-ir 0.2.0

Intermediate representation (IR) and importers for 2D CAD formats

cad2d-ir

cad2d-ir is an intermediate representation (IR) for 2D CAD data, with a common importer API and DXF conversion support.

The goal is to provide a stable, machine-friendly format for:

• CAD ingestion pipelines
• geometric post-processing
• round-trip conversion workflows

Status

The project currently supports:

• IR entities: LINE, CIRCLE, ARC, POINT, ELLIPSE, LWPOLYLINE, SPLINE, TEXT, MTEXT, INSERT, HATCH, and DIMENSION
• DXF import and export
• Native DWG import through the optional ezdwg adapter
• Native JWW import through the optional ezjww adapter
• Native SXF SFC/P21 import through the optional ezsxf adapter
• Structured importer diagnostics, statistics, and source provenance

DWG and JWW are converted from their native parser models rather than through an intermediate DXF. SFC dimensions are regrouped from the ezsxf drawing model into semantic IR dimensions with their rendered world-space geometry attached. P21 uses the same backend-neutral drawing model; its current semantic-flattening boundary is explicitly diagnosed.

See ir_schema.json for the canonical schema.

Installation

With pip

pip install cad2d-ir

Install one adapter or all adapters with:

pip install "cad2d-ir[dwg]"
pip install "cad2d-ir[jww]"
pip install "cad2d-ir[sxf]"
pip install "cad2d-ir[all]"

For development (uv)

uv sync
uv sync --all-extras  # when working with all native CAD adapters
uv run pytest

CLI

# Validate IR JSON
cad2d-ir validate examples/ir/minimal.json

# DXF -> IR
cad2d-ir dxf2ir examples/dxf/simple_line.dxf -o /tmp/out.json --pretty

# Auto-detected DXF/DWG/JWW/SFC/P21 -> IR
cad2d-ir import drawing.JWW -o /tmp/drawing.json --pretty
cad2d-ir import drawing.dwg -o /tmp/drawing.json --pretty
cad2d-ir import drawing.p21 -o /tmp/drawing.json --pretty

# Explicit adapter and approximation resolution
cad2d-ir import drawing.jww --format jww --curve-segments 128 -o /tmp/drawing.json

# IR -> DXF
cad2d-ir ir2dxf examples/ir/minimal.json -o /tmp/out.dxf

Structured importer diagnostics and export warnings are printed to stderr. --lenient skips malformed source entities and reports them instead of failing the whole import.

Python API

from cad2d_ir import convert_file_to_ir, convert_ir_to_dxf_text

to_ir = convert_file_to_ir("drawing.dwg")
print(to_ir.document["source"]["format"])  # dwg
print(to_ir.statistics["converted_entity_counts"])
for diagnostic in to_ir.diagnostics:
    print(diagnostic.code, diagnostic.message)

to_dxf = convert_ir_to_dxf_text(to_ir.document)
print(len(to_dxf.warnings))

Lower-level conversion functions (dxf_to_ir, ir_to_dxf) are also available.

Repository layout

src/cad2d_ir/
  api.py             # public high-level API
  cli.py             # CLI entrypoint
  schema.py          # schema loading + validation
  codecs/dxf.py      # DXF <-> IR conversion
  importers/         # common importer contract and format adapters
  data/ir_schema.json
ir_schema.json       # canonical schema source
tests/
examples/
docs/

Compatibility and limitations

• constraints are preserved in IR but omitted when exporting to DXF.
• JWW DIMENSION records are preserved as GENERIC dimensions; generic dimensions are omitted with a warning on DXF export rather than being mislabeled as linear dimensions.
• JWW CIRCLE_SOLID boundaries are approximated as polyline HATCH loops. The chosen segment count is recorded in approximation and reported as a diagnostic.
• DWG drawing units are currently reported as unknown because ezdwg does not expose the DWG unit header. Non-zero Z geometry is projected to XY with a diagnostic.
• DWG block bodies are reconstructed when ezdwg exposes an owner handle. Block base points are not exposed and are recorded as unresolved metadata with [0, 0] as the IR table value.
• SFC dimensions remain semantic DIMENSION entities. Other SFC curves are emitted as polylines with explicit approximation records.
• P21 currently exposes generic STEP entities plus flattened drawing primitives in ezsxf; the adapter preserves the primitives and emits SXF_P21_SEMANTICS_FLATTENED rather than claiming semantic dimensions.
• HATCH currently focuses on polyline-style loops.

Development

uv run pytest -q
uv run cad2d-ir --help

See:

• CONTRIBUTING.md
• docs/API.md
• docs/IMPORTERS.md
• docs/SCHEMA_NOTES.md

License

MIT (LICENSE)