mmg-wasm

MMG — the open-source surface and volume remeshers — compiled to WebAssembly with a typed JavaScript/TypeScript API. Mesh adaptation, isotropic/anisotropic remeshing, level-set discretization and 2D mesh generation in Node.js and the browser, no native binaries.

• All three modules in one ~1.1 MB wasm: mmg2d (planar), mmgs (surfaces), mmg3d (tetrahedral volumes) — MMG v5.8.0.
• ~350 typed functions generated from the upstream headers: the full in-memory Set_*/Get_* API (scalar and bulk typed-array variants), parameter control, and the mmg*lib/mmg*ls/mmg*mov entry points.
• File I/O through an in-memory filesystem: Medit .mesh/.sol, Gmsh .msh.
• Typed wrapper hides handles, return codes and pointer marshalling — failures throw JS Errors; dual ESM + CJS with TypeScript declarations.

Full documentation: https://loumalouomega.github.io/MMG-WASM/

Install

npm install @loumalouomega/mmg-wasm

Prebuilt WASM ships in the package — no Emscripten, CMake or compiler needed.

Quick start

Adapt the canonical MMG cube (12 vertices / 12 tetrahedra / 20 boundary triangles):

import initialize from '@loumalouomega/mmg-wasm';

const mmg = await initialize();
const { mmg3d } = mmg;

const h = mmg3d.init(); // allocates MMG5_pMesh (h.mesh) + MMG5_pSol (h.met)

mmg3d.setMeshSize(h.mesh, 12, 12, 0, 20, 0, 0);
vertices.forEach(([x, y, z], i) => mmg3d.setVertex(h.mesh, x, y, z, 0, i + 1));
tets.forEach(([a, b, c, d, ref], i) =>
  mmg3d.setTetrahedron(h.mesh, a, b, c, d, ref, i + 1));
tris.forEach(([a, b, c, ref], i) =>
  mmg3d.setTriangle(h.mesh, a, b, c, ref, i + 1));

mmg3d.setDparameter(h.mesh, h.met, mmg3d.DPARAM_hausd, 0.1);
mmg3d.remesh(h.mesh, h.met); // MMG3D_mmg3dlib

const { np, ne } = mmg3d.getMeshSize(h.mesh);
const { vertices: coords } = mmg3d.getVertices(h.mesh, np); // Float64Array
const { tetra } = mmg3d.getTetrahedra(h.mesh, ne);          // Int32Array
mmg3d.free(h);

CommonJS works too: const initialize = require('@loumalouomega/mmg-wasm').

File-based workflow (MEMFS)

const { mmg3d, FS } = await initialize();
FS.writeFile('/in.mesh', meshFileBytes);

const h = mmg3d.init();
mmg3d.loadMesh(h.mesh, '/in.mesh');
mmg3d.setDparameter(h.mesh, h.met, mmg3d.DPARAM_hausd, 0.01);
mmg3d.remesh(h.mesh, h.met);
mmg3d.saveMesh(h.mesh, '/out.mesh');
mmg3d.free(h);

const result = FS.readFile('/out.mesh'); // Uint8Array

API mapping

C functions map mechanically to module methods: MMG3D_Set_vertex → mmg.mmg3d.setVertex(...), MMG2D_Get_triangles → mmg.mmg2d.getTriangles(...). Entry points get aliases:

Module	remesh	levelset	move	generate
mmg3d	mmg3dlib	mmg3dls	mmg3dmov*	—
mmg2d	mmg2dlib	mmg2dls	mmg2dmov*	mmg2dmesh
mmgs	mmgslib	mmgsls	—	—

* Lagrangian motion requires MMG's optional elasticity library and is not functional in the WASM build.

Errors: Set_*/Get_*/load*/save* throw on failure; the entry points return MMG5_SUCCESS/MMG5_LOWFAILURE and throw only on MMG5_STRONGFAILURE. Parameter enums are constants on each module (mmg3d.DPARAM_hausd, mmg2d.IPARAM_verbose, ...).

Project structure

mmg/                  upstream MMG (git submodule, unmodified)
src/mmgjs_glue.c      fixed-arity shims for the variadic init/free functions
src/runtime.mjs       the single generic JS marshaller
scripts/              build + codegen (gen_js.py parses the MMG headers)
generated/            committed codegen output (exports, descriptor, .d.ts)
test/                 node:test suites + Playwright browser test
examples/browser/     self-contained browser demo
docs/ + mkdocs.yml    documentation site
dist/                 build output (published to npm; gitignored)

Building from source

git clone --recurse-submodules https://github.com/loumalouomega/MMG-WASM.git
cd MMG-WASM
npm run setup        # pinned Emscripten SDK -> .emsdk/
npm run build:wasm   # libmmg.a -> dist/mmg-core.{mjs,cjs,wasm} + entries
npm install && npm test

See Building from source for details (flags, debug builds, bumping the MMG version).

npm scripts

Script	Purpose
setup	install the pinned Emscripten SDK
build:wasm / build	full WASM build + dist assembly
gen	regenerate bindings from the MMG headers
test	Node tests (raw exports + typed API)
test:browser	headless-Chromium test via Playwright
docs:api / docs:build / docs:serve	documentation

Versioning

The package tracks upstream MMG (currently v5.8.0, pinned as a submodule); the wrapper has its own semver. Regenerated bindings mean new upstream API functions usually appear here with zero wrapper code.

Licensing — important

MMG is LGPL-3.0-or-later; mmg-wasm statically links it into the .wasm, and the whole package is distributed under LGPL-3.0-or-later. Using the npm package in a (proprietary) app is fine under the usual LGPL terms; see Licensing for the practical obligations and how relinking is satisfied.

This project is not affiliated with or endorsed by the Mmg consortium. If you use it in academic work, please cite the MMG papers (mmgtools.org).

Attribution

• MMG — C. Dapogny, C. Dobrzynski, P. Frey, A. Froehly and contributors.
• Built with Emscripten.