cad3d-ir-sldprt

cad3d-ir-sldprt imports SOLIDWORKS parts (.SLDPRT) and assemblies (.SLDASM) into cad3d-ir through sldkit. It does not read the Parasolid B-Rep: it takes the triangle meshes that SOLIDWORKS saved for its own display (DisplayLists), which sldkit returns as packed buffers, and writes them as one glTF binary with the same conventions as the STEP adapter. Document metadata (internal version, configuration names, custom properties, units) and the saved preview image come from sldkit's bounded metadata parse.

Assemblies are placed from what the file stores. The display stream keeps one record per component instance ahead of that instance's face tables, and the component list carries each instance's swTransform; the adapter joins the two and emits one glTF node per instance with its transform. On a four-valve FESTO manifold this reproduced the STEP export of the same assembly within a tenth of a millimetre (see cad3d_ir_sldprt.assembly).

The result is what SOLIDWORKS showed on screen when the file was saved: every visible face at the saved image quality, face outlines as edges, saved face colours as materials. Exact surfaces, dimensions and feature history are not available from this path.

The distribution depends on cad3d-ir and sldkit; the core distribution does not depend on this adapter or on sldkit.

Usage

from pathlib import Path

from cad3d_ir import DirectoryResourceWriter
from cad3d_ir.importers import ImportOptions
from cad3d_ir_sldprt import SldprtImporter

result = SldprtImporter().import_file(
    Path("bracket.SLDPRT"),
    options=ImportOptions(include_visualization_mesh=True, include_brep=False),
    resources=DirectoryResourceWriter("converted"),
)
preview = result.package.visualizations[0]  # geometry/<slug>-<key>.glb
print(preview.statistics["triangles"], preview.statistics["parts"])
for diagnostic in result.diagnostics:
    print(diagnostic.code, diagnostic.message)

cad3d-ir-sldprt bracket.SLDPRT converted/                 # manifest + GLB + preview image
cad3d-ir-sldprt bracket.SLDPRT converted/ --no-mesh       # metadata and preview only
cad3d-ir-sldprt frame.SLDASM converted/                   # placed component instances
cad3d-ir-sldprt frame.SLDASM converted/ --no-assemblies   # reject assemblies instead
cad3d-ir-sldprt bracket.SLDPRT converted/ --diagnostics report.json

What the package contains

• one SourceDocument (format="sldprt", version="SOLIDWORKS <year>" estimated from the internal version) whose properties carry the envelope, document kind, internal version, configuration names, flattened custom properties, the document length unit and the display streams;
• one part product definition with one configuration named after the document's first configuration (or Default);
• one body whose mesh representation (role="visualization", fidelity="derived", derivation.relation="tessellated") is the GLB, and a body appearance when the display data carries a saved colour;
• one package Visualization pointing at the same GLB, with triangles, line_segments, vertices, nodes, meshes and parts statistics;
• the saved preview image as a resource (preview/<slug>-<key>.png or .bmp, properties.role="preview-image"), referenced from metadata.preview_resource_id.

For an assembly the root product is an assembly, every component instance that the display stream records becomes its own part product with a configuration and (when it has geometry) a body, and the root configuration owns one Occurrence per instance with the component transform in package millimetres (visible=False for hidden components; suppressed components are left out). Face tables that cannot be joined to a placed instance, such as nested subassemblies, stay at their stored coordinates in a root body and are reported.

The GLB has one shared vertex set in millimetres, one TRIANGLES primitive per saved colour whose extras.ranges list [pick_id, first_index, index_count] per face table, and one LINES primitive with the face outlines. The pick id is the 1-based position of the face table in sldkit's mesh.parts. Node 0 converts package units to glTF metres and Y-up exactly as the STEP adapter does; SOLIDWORKS coordinates are passed through unchanged, so a part and the STEP exported from it land in the same place.

Options

ImportOptions (core): include_visualization_mesh writes the GLB (without it the package carries metadata, the preview image and an empty body); mesh_include_edges controls the outline primitive; strict turns a document without any display data into SldprtReadError; validate runs the package graph validation. The tessellation options do not apply: the mesh is the one SOLIDWORKS saved.

SldprtImporter(accept_assemblies=True, read_properties=True, include_preview=True, limit_profile="service"):

• accept_assemblies=False rejects .SLDASM documents with UnsupportedDocumentKindError. By default they are imported and placed.
• read_properties=False skips the metadata parse (a part still gets its kind and version from the display stream).
• include_preview=False leaves the preview image out.
• limit_profile is sldkit's limit profile (service is bounded for shared servers, desktop allows larger inputs).

Diagnostics

Other display.* diagnostics from sldkit are passed through as SLDPRT_DISPLAY_<CODE> with sldkit's severity and the original code in details.sldkit_code.

Current boundary

• Modern-container parts (SOLIDWORKS 2015 and later) and OLE2 parts whose display stream uses the __ZLB encoding yield meshes. OLE2 parts with the older __Zip encoding yield the preview image and metadata only.
• Drawings (.SLDDRW) are rejected. Assemblies are placed one level deep: nested subassemblies keep their stored coordinates and are reported, because their instance paths are not in the top-level component list.
• Configurations are not resolved: the display streams that SOLIDWORKS saved are returned, and a document with several mesh-bearing streams is flagged.
• Colours follow sldkit's saved precedence (body, feature, face); textures and appearances that SOLIDWORKS did not save with the display data are absent.
• The adapter is byte-faithful to sldkit: positions, normals and indices go into the GLB without conversion.

Tests

The test suite builds minimal SolidWorks documents in memory (the same frame and table grammar sldkit's own tests use) and ships no CAD file. Set CAD3D_IR_SLDPRT_SAMPLES to a directory of local .SLDPRT files to run the optional sample check.

License

cad3d-ir-sldprt is source-available under the PolyForm Noncommercial License 1.0.0, following sldkit, with separate commercial licenses from UnRobotics Inc. See LICENSE. The cad3d-ir core and cad3d-ir-step in the same repository remain MIT.

Required Notice: cad3d-ir-sldprt is licensed by UnRobotics Inc. (https://www.un-robotics.com/). Required Notice: cad3d-ir-sldprt is offered under PolyForm Noncommercial 1.0.0; separate commercial licenses are available.