castiron

Compile a CADbuildr foundation design into geometry by casting its DAG into IronStream solids via the ironstream Python binding.

castiron is the end-to-end Python path: foundation (Python) → compile() → IronStream kernel (Rust, via the Python binding) → a file on disk. It is the offline, in-process counterpart to foundation's show() — no broker, no network, no kernel-api.

from cadbuildr.foundation import Part, Sketch, Point, Line, Polygon, Extrusion
from castiron import compile

class Cube(Part):
    def __init__(self, size=20):
        s = Sketch(self.xy())
        p1, p2, p3, p4 = Point(s,0,0), Point(s,size,0), Point(s,size,size), Point(s,0,size)
        poly = Polygon([Line(p1,p2), Line(p2,p3), Line(p3,p4), Line(p4,p1)])
        self.add_operation(Extrusion(poly, size))

manifest = compile(Cube(20), format="stl")
print(manifest.files)   # ['.cadbuildr/build/<dag-hash>/cube.stl']

compile() accepts a foundation Part/Assembly (or an already-serialized DAG dict from foundation.dag_utils.show_dag) and writes stl, step, or json (glTF-like mesh). Output is content-addressed by DAG hash, so a repeated build is a cache hit:

<out_dir>/<dag_hash>/<part_name>.<ext>
<out_dir>/<dag_hash>/manifest.json

How it works

Two pieces (see src/castiron/):

1. dag.py — the DAG tool: parses foundation's CompilerInputDAG, inverts the numeric type table to type names, and topologically orders the nodes.
2. nodes.py — the conversion functions: one handler per foundation node type, each emitting IronStream binding calls (make_polygon → make_face → make_prism, make_revol, booleans, …). placement.py maps 2D sketch coordinates into 3D world space.

Adding a node type = writing one handler and registering it in HANDLERS.

Status

Handlers exist for every foundation node type. Against the kernel-truck fixture corpus, 64/70 compile to geometry and 5 more are legitimately sketch-only or empty designs (no solid) — 69/70 accounted for.

Covered: parameters; points/lines/arcs/splines/3D points; closed shapes (polygon, rectangle, square, hexagon, circle, ellipse, custom); sketches / planes / frames (quaternion placement); Extrusion, Hole, Lathe, Sphere; Mirror, Scale, Shell, Stitch; Loft / SurfaceLoft / Sweep / MultiSectionSweep / Helix3D (mesh skinning via ironstream.solid_from_mesh); sheet-metal base + edge flange (other bends forward the flange, matching the Rust reference); Assembly (multi-part, frame-chained placement); and SVGShape (path flattening).

Approximations / gaps, in order of fidelity cost:

• Fillet / Chamfer / Draft / FullRound forward the solid unchanged — the IronStream kernel exposes no edge-blend op yet (neither does the Rust reference).
• Sheet-metal bends (Tab/Hem/Miter/Unfold) forward the base flange; no bend deformation.
• SVGShape flattens <path> data as a single loop (multi-subpath holes and self-intersecting art are approximate); SVG <text> needs a font engine and is unsupported.

Development

Install alongside the sibling repos (ironstream-python, cadbuildr-foundation):

uv pip install -e .
pytest