cadmpeg-codec-f3d

cadmpeg-codec-f3d decodes Autodesk Fusion .f3d archives into CadIr and encodes supported CadIr documents back to .f3d. The codec covers ZIP container metadata, ASM B-rep topology, analytic and cached NURBS geometry, body transforms, design and sketch records, construction history, and appearances.

Support level: L4 on the cadmpeg support ladder.

Install

cargo add cadmpeg-codec-f3d cadmpeg-ir

Decode

use cadmpeg_codec_f3d::F3dCodec;
use cadmpeg_ir::{Codec, DecodeOptions};
use std::fs::File;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut input = File::open("part.f3d")?;
    let result = F3dCodec.decode(&mut input, &DecodeOptions::default())?;

    for loss in &result.report.losses {
        eprintln!("{:?}: {}", loss.severity, loss.message);
    }
    println!("{} bodies", result.ir.model.bodies.len());
    Ok(())
}

The result contains the decoded CadIr and a DecodeReport. Check report.losses before using geometry from files that may contain unsupported record forms. Set DecodeOptions::container_only when you need archive metadata without B-rep decoding. F3dCodec::inspect returns the classified ZIP entries and B-rep header facts.

Encode

use cadmpeg_codec_f3d::F3dCodec;
use cadmpeg_ir::{Codec, DecodeOptions, Encoder};
use std::fs::File;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut input = File::open("part.f3d")?;
    let mut result = F3dCodec.decode(&mut input, &DecodeOptions::default())?;

    // Edit supported fields in result.ir.

    let mut output = File::create("part-edited.f3d")?;
    F3dCodec.encode(&result.ir, &mut output)?;
    Ok(())
}

Decode retains the source archive and records a semantic baseline. Encoding an unchanged result replays the original bytes. After supported edits, encoding patches the retained archive and preserves unmodified entries and records. Encoding a CadIr without retained F3D source data creates a canonical archive for the supported source-less profile.

Data model and support

The decoder selects the .smbh history stream, or the first .smb when no .smbh exists. The Design body map selects every B-rep blob contributing bodies to the document model. The decoder frames their SAB record slices and builds each topology chain from bodies through vertices and points. ASM model-space lengths become millimetres in CadIr; directions, ratios, angles, knots, weights, and UV parameters retain their native scale.

Analytic carriers include planes, cylinders, cones, spheres, tori, lines, circles, and ellipses. The codec also reads cached NURBS surfaces, 3D curves, and pcurves, selected procedural definitions, source attributes, design joins, sketch entities, typed ASM history, and Protein appearances.

Records that prevent faithful transfer appear in DecodeReport::losses. Referenced carrier bytes that remain useful for passthrough are stored as UnknownRecord values. If SAB framing or geometry decoding fails, the result contains container metadata and retained source data with blocking geometry and topology losses.

Display meshes, complete component structure, assembly constraints, and replayable feature history are outside current support. The format-support matrix lists decode and encode coverage.

Documentation

Requires Rust 1.88 or later. Licensed under Apache-2.0.