This package provides a tool to parse MNI OBJ mesh/surface files. Those are generally generated by CIVET as an output of extracting the white/grey matter from MRI data.
Both CIVET and this package are being developed and maintained by MCIN lab.

DEMO, see the examples folder of the repo.
DOCUMENTATION

Read more about the MNI OBJ file format here.

How to

In a npm project

$ npm install --save mniobjparser

Then use import (e.g. in a Rollup project):

import { MniObjParser } from 'mniobjparser';
...
var myParser = new MniObjParser();

In a stand alone webpage

<script src="mniobjparser/dist/mniobjparser.umd.js"></script>
<!-- OR the minified version -->
<script src="mniobjparser/dist/mniobjparser.umd.min.js"></script>

Then use it with a reference to its module:

var myParser = new mniobjparser.MniObjParser();

Then, no matter in what context you are using it, the following is the same. A MNI OBJ file is a (potentially very long) text file, and depending on your project you may waht to open such files from the local machine using a open file dialog or from a distant server with an AJAX request. This is your choice and this quick how to will not cover this part, so in the following we assume that your Javascript code already has access to the very long String content of a MNI OBJ file.

// parse the string content or the MNI OBJ file:
myParser.parse( largeMniObjString )

// Check if the parsing went ok:
if( !parser.isValid() ){
  alert("Invalid MNI OBJ file.\n" + "ERROR: " + parser.getErrorMessage());
  return;
}

// get the position of all the vertices as [x, y, z, x, y, z, ... ]
var positions = parser.getRawVertices();  // Float32Array

// get the index of the vertices involved in faces. These are the index from the "positions" array
// [index0, index1, index2, index0, index1, index2, ... ] , each are triangles
var indices = parser.getShapeRawIndices(); // Uint32Array

// get the list of normal vectors (unit) as [x, y, z, x, y, z, ... ]
var normals = parser.getRawNormals(); // Float32Array

// get all the colors per vertex as [r, g, b, a, r, g, b, a, ... ]
var colors = parser.getRawColors(); // Uint8Array

// get some material information, not mandatory to reconstruct the mesh
var surfaceProperties = parser.getSurfaceProperties(); // object

Then, using ThreeJS (or other) you can rebuild the mesh, just like in this example.