This project is part of the @thi.ng/umbrella monorepo.

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Wavefront OBJ parser (& exporter soon). This is a support package for @thi.ng/geom.

• Geometry split into declared objects & groups by default (can be disabled)
• Full support for n-gon faces, polylines
• Optional n-gon face tessellation into triangles
• Support for relative (negative) vertex references
• Optional vertex, normal & UV transforms (e.g. convert Y-up / Z-up, flip UVs)
• Skip parsing/processing of UVs and/or normals
• Per group mtllib and usemtl references
• Per group smooth flags
• Optionally retained comments (e.g. for additional metadata parsing)
• Fast (~100 verts, normals & faces per millisecond, MBP2015, Node 13.10)

• OBJ export
• MTL parser

ALPHA - bleeding edge / work-in-progress

Search or submit any issues for this package

yarn add @thi.ng/geom-io-obj

ES module import:

<script type="module" src="https://cdn.skypack.dev/@thi.ng/geom-io-obj"></script>

Skypack documentation

For Node.js REPL:

# with flag only for < v16
node --experimental-repl-await

> const geomIoObj = await import("@thi.ng/geom-io-obj");

Package sizes (gzipped, pre-treeshake): ESM: 1.03 KB

• @thi.ng/api
• @thi.ng/errors
• @thi.ng/vectors

Generated API docs

TODO

See api.ts for details about resulting data structure. Also see tests for more.

import { parseObj } from "@thi.ng/geom-io-obj";

const src = `
# test cube

v 1.0000 1.0000 1.0000
v 1.0000 1.0000 0.0000
v 1.0000 0.0000 0.0000
v 1.0000 0.0000 1.0000
v 0.0000 1.0000 0.0000
v 0.0000 1.0000 1.0000
v 0.0000 0.0000 1.0000
v 0.0000 0.0000 0.0000

# quad faces
f 4 3 2 1
f 8 7 6 5
f 6 1 2 5
f 8 3 4 7
f 7 4 1 6
f 3 8 5 2
`;

// parse with defaults
const model = parseObj(src);

console.log(model.vertices);
// [
//   [ 1, 1, 1 ],
//   [ 1, 1, 0 ],
//   [ 1, 0, 0 ],
//   [ 1, 0, 1 ],
//   [ 0, 1, 0 ],
//   [ 0, 1, 1 ],
//   [ 0, 0, 1 ],
//   [ 0, 0, 0 ]
// ]

// vertex indices now zero-based (instead of 1-based in OBJ)
console.log(model.objects[0].groups[0].faces);
// [
//   { v: [ 3, 2, 1, 0 ] },
//   { v: [ 7, 6, 5, 4 ] },
//   { v: [ 5, 0, 1, 4 ] },
//   { v: [ 7, 2, 3, 6 ] },
//   { v: [ 6, 3, 0, 5 ] },
//   { v: [ 2, 7, 4, 1 ] }
// ]

Benchmark uses a quad-mesh model with 143,423 vertices, same number of normals and 142,802 quad faces (filesize 43.7MB).

benchmarking: parse
        warmup... 7299.40ms (5 runs)
        executing...
        total: 13795.25ms, runs: 10
        mean: 1379.52ms, median: 1379.91ms, range: [1356.43..1431.49]
        q1: 1362.21ms, q3: 1415.23ms
        sd: 1.77%

benchmarking: parse w/ tessellation
        warmup... 7752.45ms (5 runs)
        executing...
        total: 15170.43ms, runs: 10
        mean: 1517.04ms, median: 1540.89ms, range: [1425.28..1616.09]
        q1: 1487.29ms, q3: 1551.26ms
        sd: 3.35%

Karsten Schmidt

If this project contributes to an academic publication, please cite it as:

@misc{thing-geom-io-obj,
  title = "@thi.ng/geom-io-obj",
  author = "Karsten Schmidt",
  note = "https://thi.ng/geom-io-obj",
  year = 2016
}

© 2016 - 2021 Karsten Schmidt // Apache Software License 2.0