function.js

const express = require('express');
const multer = require('multer');
const assert = require('fluent-assert');
const recast = require('@donmccurdy/recast');
const RecastConfig = require('./src/recast-config');

const PORT = process.env.PORT || 3000;

// ---------------------------------------- //

const app = express();

const upload = multer({ storage: multer.memoryStorage(), limits: {fileSize: '50mb'} })
  .fields([{ name: 'position', maxCount: 1 }, { name: 'index', maxCount: 1 }]);

// ---------------------------------------- //

app.use(function(req, res, next) {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Headers', 'Origin, X-Requested-With, Content-Type, Accept');
  next();
});

// ---------------------------------------- //

app.post('*', upload, (req, res) => {

  const files = req.files || {};
  if (!files.position || !files.index) return res.sendStatus(400);

  let config;

  // Validate configuration.
  try {

    config = RecastConfig.map((param) => {
      assert.ok(param.name, req.query[param.name]);
      const value = Number(req.query[param.name]);
      assert.number(param.name, value).range(param.min, param.max);
      return value;
    });

  } catch (e) {

    console.error(e);
    res.send({ok: false, message: e.message});
    return;

  }

  // Load input.
  try {

    // Buffer references. Buffer.prototype.buffer is an ArrayBuffer.
    const positionBuffer = files.position[0].buffer;
    const indexBuffer = files.index[0].buffer;

    const position = new Float32Array(
      positionBuffer.buffer,
      positionBuffer.byteOffset,
      positionBuffer.byteLength / Float32Array.BYTES_PER_ELEMENT
    );
    const index = new Uint32Array(
      indexBuffer.buffer,
      indexBuffer.byteOffset,
      indexBuffer.byteLength / Uint32Array.BYTES_PER_ELEMENT
    );

    console.log(`${position.length / 3} vertices, ${index.length / 3} faces.`);

    if (!position.length || !index.length) {
      throw new Error('No mesh data.');
    }

    console.time('recast::load');
    recast.load(position, index);
    console.timeEnd('recast::load');

  } catch (e) {

    console.error(e);
    res.send({ok: false, message: 'Invalid mesh.'});
    return;

  }

  // Construct navmesh.
  try {

    console.time('recast::build');
    const output = recast.build.apply(recast, config).replace(/@/g, '\n');
    console.timeEnd('recast::build');

    if (output.indexOf('v') === -1) {
      throw new Error('Empty navmesh.');
    }

    console.time('recast::send');
    res.send({ok: true, obj: output});
    console.timeEnd('recast::send');

  } catch (e) {

    console.error(e);
    res.send({ok: false, message: 'Failed to build navigation mesh.'});

  }

});

// ---------------------------------------- //

module.exports = app;

// ---------------------------------------- //