Module fusion 

Autodesk Fusion design archives (.f3d).

A design is a ZIP archive with one folder per document (FusionAssetName[Active]/…). Most entries are compressed with Zstandard (ZIP method 93), a few are stored; Deflate is accepted too. The zip crate reads the directory; Zstandard entries are inflated with ruzstd (pure Rust) and checked against the stored size and CRC-32.

Entries used by TeamCraft (see mesh::f3d and docs/src/research/fusion-ogs-preview.md):

• OGS.BlobFolder/OGS/DefaultScene/world and stream_mesh_NNN: the display scene of Fusion’s graphics system with the triangles of every face (the 3D preview);
• Previews/big.png: the thumbnail Fusion rendered when saving.

Hostile input: an entry is inflated only when its stored size is within the caller’s limit, inflating stops one byte after that size, and the result must have exactly the stored size and CRC-32.

Structs

Archive

An opened design archive.

Constants

PREVIEW_PNG

The thumbnail Fusion stores.

SCENE_DIR

Folder of the display scene inside a document folder.

SCENE_WORLD

The scene graph of the display scene.

Functions

is_archive

Whether head (the first bytes of a file) starts a Fusion archive: a ZIP whose first entry is a Fusion document folder or manifest.