I/O

Tools for bringing geometry into the scene from disk, exporting the scene to standard CAD formats, and annotating XCAF assembly documents with structured metadata. Use these when loading existing BREPs or neutral-format files, shipping deliverables, or stamping part numbers and materials onto an assembly.

Tools

• read_brep · import_file · export_scene · set_assembly_metadata

read_brep

Add a .brep file from disk to the scene as a new body.

Server: Swift + Node

Parameters

Returns: The updated scene manifest entry for the new body, including its assigned bodyId and bounding info. Returns an error if the file does not exist or fails to parse (and allowInvalid is false).

A file that parses but holds nothing with a bounding box (an empty or null shape) is also an error. The bounding box is read before the scene is written, so this case leaves the scene untouched rather than registering a body whose reported extent would have to be invented.

Example

// tool call arguments
{ "inputPath": "/Users/me/output/part.brep", "bodyId": "part", "color": [0.7, 0.7, 0.8] }

// example result
{ "bodyId": "part", "name": "part", "path": "/Users/me/output/part.brep" }

Notes: Set allowInvalid: true when loading a mesh-reconstructed solid that has open shells or non-manifold edges; the shape is added as-is so you can immediately call validate_geometry to inspect its defects or measure_deviation to certify it against a reference mesh. The validity gate is re-applied on the next export_scene call. On the Swift server a body whose file name (<id>.brep) another body already has, compared without regard to case, is refused instead of overwriting that body’s file.

import_file

Multi-format CAD import (STEP / IGES / BREP / STL / OBJ). Adds the imported shape as a single body.

Server: Swift (STL / OBJ mesh formats are Swift-only)

Parameters

Returns: The scene manifest entries for all bodies added, each with its bodyId. Returns an error if the format is unrecognised or import fails.

Example

// tool call arguments
{ "inputPath": "/Users/me/models/bracket.step", "format": "step", "idPrefix": "bracket" }

// example result
{ "added": [{ "bodyId": "bracket_0", "name": "bracket_0" }] }

Notes: Like read_brep, allowInvalid: true bypasses the write-gate so you can load a loose-face or open-shell STEP file produced by a reconstruction tool and immediately measure it with measure_deviation or validate_geometry. STEP assemblies with multiple solids produce one body per solid, each prefixed with idPrefix. On the Swift server a body whose file name (<id>.brep) another body already has, compared without regard to case, is refused instead of overwriting that body’s file.

BREP (.brep / .brp) is a single shape, so it imports as one body. On the Swift server it loads in-process via Shape.loadBREP. On the Node server it is routed to the occtkit load-brep verb (occtkit’s import verb itself has no BREP loader), so import_file is a single entry point for every format on both servers (you don’t need to fall back to read_brep for BREP).

Mesh formats (STL / OBJ) load in-process on the Swift server as a raw triangulated shell (Shape.loadSTL / Shape.loadOBJ, no sew/heal so an open scan skin isn’t distorted). Because a mesh shell isn’t a valid solid, the write-gate is skipped automatically for these formats (you don’t need allowInvalid). This is the front door for a reference scan / STL skin, import it, then certify a reconstruction against it with measure_deviation or cross_section_compare.

export_scene

Export the current scene (or a named subset of bodies) to STEP / IGES / BREP / STL / OBJ / glTF / GLB.

Server: Swift + Node

Parameters

Returns: Confirmation with the written outputPath and the list of body IDs exported. Returns an error if no scene bodies exist or the path is not writable.

Example

// tool call arguments
{ "format": "step", "outputPath": "/Users/me/output/assembly.step" }

// example result
{ "outputPath": "/Users/me/output/assembly.step", "exported": ["base", "bracket", "lid"] }

Notes: glb produces a single binary glTF bundle suitable for web viewers. Use bodyIds to isolate a subassembly without removing bodies from the scene. Internally this runs a one-shot templated script via occtkit on both the Swift and Node servers.

set_assembly_metadata

Write XCAF document- or component-level metadata onto an OCAF document and save as binary .xbf. Mirrors occtkit set-metadata.

Server: Swift + Node

Parameters

metadata sub-fields (all optional within the object):

Returns: Confirmation with the written outputPath. Returns an error if the input file cannot be read or the output path is not writable.

Example

// tool call arguments
{
  "inputPath": "/Users/me/output/assembly.step",
  "outputPath": "/Users/me/output/assembly_meta.xbf",
  "scope": "document",
  "metadata": {
    "title": "Mounting Bracket",
    "partNumber": "MB-0042",
    "revision": "B",
    "material": "6061-T6 Aluminium",
    "drawnBy": "E. Lynch-Bell",
    "customAttrs": { "project": "OCCTMCP-demo" }
  }
}

// example result
{ "outputPath": "/Users/me/output/assembly_meta.xbf" }

Notes: The output is always .xbf (binary OCAF format), regardless of the input format. To target a specific sub-component, set scope: "component" and provide componentId (zero-based index into the XCAF shape tree). Use inspect_assembly (see Introspection & measurement) to discover component indices first. An .xbf input (such as a previous output) is read with the OCAF reader and keeps its earlier metadata. An empty file, a file without the binary OCAF BINFILE header, or a body the reader rejects returns an error naming the cause.