Example Node.js glTF conversion script, using three.js.

FOO2GLTF.js

#!/usr/bin/env node

const fs = require('fs');
const path = require('path');
const THREE = require('three');
const program = require('commander');
const Canvas = require('canvas');
const { Blob, FileReader } = require('vblob');

// Patch global scope to imitate browser environment.
global.window = global;
global.Blob = Blob;
global.FileReader = FileReader;
global.THREE = THREE;
global.document = {
  createElement: (nodeName) => {
    if (nodeName !== 'canvas') throw new Error(`Cannot create node ${nodeName}`);
    const canvas = new Canvas(256, 256);
    // This isn't working — currently need to avoid toBlob(), so export to embedded .gltf not .glb.
    // canvas.toBlob = function () {
    //   return new Blob([this.toBuffer()]);
    // };
    return canvas;
  }
};

// https://github.com/mrdoob/three.js/issues/9562
require('three/examples/js/exporters/GLTFExporter');

program
  .version('0.0.1')
  .usage('[options] <file>')
  .option('-o, --output <file>', 'output filename', String)
  // .option('-b, --binary', 'use binary (.glb) format (default false)')
  .option('-m, --myoption', 'my custom option (default 1.0)', Number)
  .parse(process.argv);

program.binary = !!program.binary;
program.myoption = program.myoption || 1;

const inputPath = program.args[0];
if (!inputPath) { program.help(); }

if (!program.output) {
  program.output = path.basename(inputPath, '.foo');
  program.output += program.binary ? '.glb' : '.gltf';
}

console.log(' → input: %j', program.args);
console.log(' → output: %j', program.output);
console.log(' → binary: %j', program.binary);
console.log(' → my custom option: %j', program.myoption);

console.log(`Loading "${inputPath}"`);
let mesh = new THREE.Mesh(...); // (load or create mesh here)

console.log('Converting to glTF');
const exporter = new THREE.GLTFExporter();
exporter.parse(mesh, (content) => {

  console.log(`Writing to ${program.output}`);
  if (typeof content === 'object') content = JSON.stringify(content);
  fs.writeFileSync(program.output, content);

}, {binary: program.binary});

@sanghiad if you mean a three.js THREE.Mesh instance, then, sort of. A glTF file may have multiple meshes in it, or a combination of meshes and other things (materials, animations, lights, etc.). The typical way to turn all of that into three.js objects, including THREE.Mesh where appropriate, is THREE.GLTFLoader.

If you mean turning a glTF file into some other file type, I would recommend using Blender or other 3D software to do conversions.

@donmccurdy @mrdoob Really useful to work with Three outside of the browser. To get the above gist working in Node 18 a couple of tweaks are needed. Node 14 introduced a native Blob object and vblob exports global.Blob if present. However, the vblob FileReader expects a VBlob class to work properly. Workaround to force use of VBlob is to set global.Blob=null before importing the vblob module. But I guess this workaround may introduce issues if you rely on the Node Blob class for other purposes. Issue filed here: karikera/vblob#1