OpenSkp.Fragments 1.3.0

OpenSkp.Fragments

Direct SketchUp (.skp) → ThatOpen Fragments (.frag) export — EXPERIMENTAL.

Converts an OpenSkp InstancedScene directly to ThatOpen's own FlatBuffers-based .frag binary format (https://github.com/ThatOpen/engine_fragment) — the format their @thatopen/fragments/@thatopen/components viewer stack actually loads and streams. Skips the common .skp → IFC (text) → web-ifc WASM → .frag round trip through IFC's verbose ASCII STEP format entirely.

Ships as its own package, separate from the core OpenSkp package, because it needs Google.FlatBuffers — the core package has zero external dependencies, and this mirrors Python's own opt-in pip install openskp[fragments] extra instead of forcing every OpenSkp.NET consumer to take a transitive dependency they don't need.

Usage

using OpenSkp;
using OpenSkp.Fragments;

byte[] skpBytes = File.ReadAllBytes("model.skp");
var scene = SkpFile.BuildInstancedScene(skpBytes);

FragmentsExport.ExportFragments(scene, "model.frag");
// or, in memory:
byte[] fragBytes = FragmentsExport.ToFragments(scene);

Status — stated plainly

Export only (no .frag → InstancedScene reader yet), matching the TypeScript port's own scope, not Python's/C++'s fuller read+write one (TypeScript has no read side either — not a gap unique to .NET). GUID/name-is-generated/layer-hidden fidelity matches Python's/C++'s in full: InstancedNode/InstancedScene in the core OpenSkp package carry real per-instance source GUIDs (from the source file's own attribute dictionaries), a generated-name flag, and the source file's real per-layer visibility state — a duplicated real GUID (openskp#290 — SketchUp's own Copy/Array tools can carry one plugin-authored GUID to several distinct physical instances) gets the same synthetic- fallback treatment as a missing one, so IDs stay unique either way.

Non-uniform scale and mirrored (negative-determinant) instance transforms ARE fully supported: Fragments' Transform struct has no scale field at all, so this module bakes each instance's scale/mirror into its own geometry variant before writing. Instances sharing the exact same (definition, scale) combination still dedupe onto one shared Shell.

See the core OpenSkp README for the full cross-language picture, and openskp.export.fragments (the Python original this was ported from) for the complete rationale and real-loader verification history.

License

MIT — see LICENSE.