Reference Adapters Catia

Relevant source files

The following files were used as context for generating this wiki page:

• src/convert/adapters/catia/Adapter.py
• src/convert/adapters/catia/Container.py
• tests/convert/catia/CatiaTests.py
• re/Methodology.md
• src/convert/adapters/catia/Format.py

CATIA Format Adapter

The CATIA Format Adapter enables the Kit SDK to read and write CATIA V5 files. It handles the extraction of geometry, feature history, and assembly structures from .CATPart and .CATProduct containers. The adapter treats these files as CFBF (Compound File Binary Format) envelopes containing various binary streams and records.

Architecture Overview

The adapter consists of four primary components that implement the standard Kit adapter interface. These components handle metadata identification, source probing, document reading, and destination writing.

classDiagram
    class CatiaAdapter {
        +probe(Source) ProbeResult
        +read(Source, ReadOptions) CadDocument
        +write(CadDocument, Destination, WriteOptions) WriteResult
        +supports(CadDocument, Destination) bool
    }
    class CatiaMetadata {
        +info AdapterInfo
    }
    class CatiaReader {
        +read(Source, ReadOptions)
    }
    class CatiaWriter {
        +write(Doc, Target, Options)
    }
    class CatiaSupport {
        +CanSupport(Doc, Target)
    }
    CatiaAdapter --|> CatiaMetadata
    CatiaAdapter --|> CatiaReader
    CatiaAdapter --|> CatiaWriter
    CatiaAdapter --|> CatiaSupport

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The diagram shows the class hierarchy of the CATIA adapter, combining metadata, reading, writing, and support logic.

Container Structure

CATIA V5 files utilize the V5_CFV2 container format. This format organizes data into an outer directory and optional nested directories, each containing multiple data streams. The adapter parses these streams to identify the document type and extract payloads.

Supported Streams

Stream Name	Purpose	Role
1000_00000002_2	Primary Part Data	Feature History
1000_00000001_1	Primary Product Data	Assembly Structure
Format	Document Type Marker	Metadata
KitInterchange	Embedded Kit Manifest	Document
CATSummaryInformation	Version and Application Info	Metadata

Read Logic

The CatiaReader processes V5_CFV2 archives by detecting the document type and extracting native payloads. If a KitInterchange stream exists, it restores the neutral document from the embedded manifest.

flowchart TD
    A[Start Read] --> B{Manifest Present?}
    B -- Yes --> C[Read Embedded Document]
    B -- No --> D[Detect Document Type]
    D --> E[Identify OSMX Graphs]
    E --> F[Extract Brep/Tessellation]
    F --> G[Build CadDocument]
    C --> H[Apply Read Filters]
    H --> G

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The flow diagram illustrates the decision path between reading a native CATIA file and restoring an embedded Kit document.

Payload Identification

The adapter classifies binary streams based on signatures and declarations:

• OSMX: Native feature history or assembly structure.
• CGM: Native B-Rep geometry.
• MFBRP: B-Rep topology data.
• CGR: Native tessellation (SceneGraph/SurfacicReps).

Write Logic

The CatiaWriter supports three primary write modes based on the availability of the source document's own native data and the target configuration.

Write Modes

Mode	Description	Compatibility
exact_native_roundtrip	Replays original native bytes for unmodified documents.	native-exact
native_base_with_neutral_edits	Preserves native streams but adds a neutral manifest for edits.	native-base-neutral-overlay
generated_cfv2	Generates a new CFV2 container from scratch with embedded neutral data.	kit-neutral-only

Native Base Preservation

When native-base-neutral-overlay is active, the adapter appends a KitInterchange stream to an existing CATIA file. This preserves the original native features for CATIA while allowing Kit to store changes in a neutral format.

sequenceDiagram
    participant W as CatiaWriter
    participant D as Donor Bytes
    participant M as Manifest
    participant T as Target File
    W->>D: Load Native Base
    W->>M: Pack Neutral Document
    M->>M: Compress (Zlib Level 9)
    W->>D: Append Cfv2 Stream "KitInterchange"
    D->>T: Write Combined Bytes

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This sequence shows how the adapter overlays neutral Kit data onto native source-document bytes.

Semantic Validation

To ensure data integrity, the adapter calculates a catia.roundtrip_sha256 digest. This digest is a hash of the document's semantic content, excluding specific source-dependent metadata and the native envelope payloads themselves.

Implementation Details

The adapter uses standard Python libraries for low-level data handling:

• struct: For parsing binary headers and extent offsets.
• hashlib: For generating SHA256 digests of streams and manifests.
• zlib: For compressing and decompressing the embedded Kit manifest.

OSMX Graph Extraction

The adapter identifies native features by searching for OSMX markers within the container. It maps these graphs to FeatureStep and Body records in the CadDocument, allowing for basic structural representation of the part history.

Conclusion

The CATIA Format Adapter provides a robust bridge between CATIA V5 files and the Kit neutral model. By supporting both native byte replay and generated neutral carriers, it ensures maximum interoperability while preserving original proprietary data whenever possible.

Carrier and neutral-overlay modes preserve data but do not establish editable native CATIA features. Inspect the output attestation and require target-application acceptance; see Getting started.