#gamedev #graphics #wavefront #obj #mtl

nobject-rs

A parser for wavefront Obj/Mtl files. Written with Nom.

4 stable releases

1.1.1 Jun 26, 2021
1.1.0 Jun 20, 2021
1.0.1 Jun 16, 2021
1.0.0 Jun 13, 2021

#7 in Data formats

MIT license

125KB
3.5K SLoC

Overview

nobject-rs is a library for parsing wavefront .obj and .mtl content. To this end, the crate exposes two methos:

  • load_obj
  • load_mtl

Both methods take the content of the respective files (.obj and .mtl), parse and then return a result with either some kind of parse error, or a struct containing the data.

Note that this crate leaves the responsibility of file I/O to the consuming application. For example, it's possible to specify file names as attributes in the material, or file names as material libraries in the obj file. This library will NOT attempt to open and parse those files. It is left to the consuming application/library to take the file information from the results of the parse methods, find and open the appropriate files, and then pass on the contents to be parsed.

Reference

Parsing is done based on the specification for Obj's and Mtl's found at:

Examples

Obj parsing

fn main() {
    let input =
    "
    o 1
    v -0.5 -0.5 0.5
    v -0.5 -0.5 -0.5
    v -0.5 0.5 -0.5
    v -0.5 0.5 0.5
    v 0.5 -0.5 0.5
    v 0.5 -0.5 -0.5
    v 0.5 0.5 -0.5
    v 0.5 0.5 0.5
    
    usemtl Default
    f 4 3 2 1
    f 2 6 5 1
    f 3 7 6 2
    f 8 7 3 4
    f 5 8 4 1
    f 6 7 8 5
    ";

    let res = nobject_rs::load_obj(&input).unwrap();
    let group = &res.groups["default"];
    let face_group = &res.faces["default"];
    assert_eq!(res.vertices.len(), 8);
    assert_eq!(group.material_name, "Default".to_string());
    assert_eq!(res.normals.len(), 0);
    assert_eq!(res.faces.len(), 1);
    assert_eq!(face_group.len(), 6);;
}

Mtl parsing

fn main() {
    let input =
    "newmtl frost_wind
    Ka 0.2 0.2 0.2
    Kd 0.6 0.6 0.6
    Ks 0.1 0.1 0.1
    d 1
    Ns 200
    illum 2
    map_d -mm 0.200 0.800 window.mps";

    let res = nobject_rs::load_mtl(&input).unwrap();
    assert_eq!(res.len(), 1);
}

Dependencies

~3MB
~63K SLoC