Module obj 

Wavefront OBJ format import and export.

This module provides conversion between OBJ files and 3MF Model structures.

OBJ Format

The Wavefront OBJ format is a text-based 3D geometry format. This implementation supports:

Supported features:

• v - Vertex positions (x, y, z)
• f - Faces (vertex indices, with automatic fan triangulation for polygons)
• g / o - Group/object directives (each creates a separate 3MF Object)
• usemtl - Material assignment (maps to per-triangle pid/p1/p2/p3)
• mtllib - Material library file reference (parsed via mtl module)

Ignored features:

• vt - Texture coordinates
• vn - Vertex normals

Material Import

When using ObjImporter::read_from_path, the importer resolves mtllib directives relative to the OBJ file’s directory. MTL Kd (diffuse color) maps to 3MF BaseMaterial display colors. Materials are collected into a single BaseMaterialsGroup resource.

When using ObjImporter::read, no MTL resolution is possible and materials are not imported (geometry-only mode for backward compatibility).

Examples

Importing OBJ with materials

use lib3mf_converters::obj::ObjImporter;
use std::path::Path;

let model = ObjImporter::read_from_path(Path::new("model.obj"))?;
println!("Imported model with {} build items", model.build.items.len());

Importing OBJ (geometry only)

use lib3mf_converters::obj::ObjImporter;
use std::fs::File;

let file = File::open("model.obj")?;
let model = ObjImporter::read(file)?;
println!("Imported model with {} build items", model.build.items.len());

Exporting OBJ

use lib3mf_converters::obj::ObjExporter;
use lib3mf_core::model::Model;
use std::fs::File;

let file = File::create("output.obj")?;
ObjExporter::write(&model, file)?;

Structs

ObjExporter

Exports 3MF Model structures to Wavefront OBJ files.

ObjImporter

Imports Wavefront OBJ files into 3MF Model structures.