occt-import-js

The emscripten interface for OpenCascade import functionalities. It runs entirely in the browser, and allows you to import step files and access the result in JSON format.

See it in action in Online 3D Viewer.

How to install?

You can get occt-import-js from npm:

npm install occt-import-js

How to use?

The library runs in the browser and as a node.js module as well.

You will need two files from the dist folder: occt-import-js.js and occt-import-js.wasm. The wasm file is loaded runtime by the js file.

Use from the browser

First, include the occt-import-js.js file in your website.

<script type="text/javascript" src="occt-import-js.js"></script>

After that, download the model file, and pass them to occt-import-js.

occtimportjs ().then (async function (occt) {
	let fileUrl = '../test/testfiles/simple-basic-cube/cube.stp';
	let response = await fetch (fileUrl);
	let buffer = await response.arrayBuffer ();
	let fileBuffer = new Uint8Array (buffer);
	let result = occt.ReadStepFile (fileBuffer);
	console.log (result);
});

Use as a node.js module

You should require the occt-import-js module in your script.

let fs = require ('fs');
const occtimportjs = require ('occt-import-js')();

occtimportjs.then ((occt) => {
	let fileUrl = '../test/testfiles/simple-basic-cube/cube.stp';
	let fileContent = fs.readFileSync (fileUrl);
	let result = occt.ReadStepFile (fileContent);
	console.log (result);
});

Processing the result

The result of the import is a JSON object. The success field tells if the import was successful. The meshes object is an array of three.js compatible mesh objects.

{
    "success": true,
    "meshes": [
        {
            "attributes": {
                "position": {
                    "array": [...]
                },
                "normal": {
                    "array": [...]
                }
            },
            "index": {
                "array": [...]
            }
        }
    ]
}

How to build on Windows?

A set of batch scripts are prepared for building on Windows.

1. Install Prerequisites

Install CMake (3.6 minimum version is needed). Make sure that the cmake executable is in the PATH.

2. Install Emscripten SDK

Run the Emscripten setup script.

tools\setup_emscripten_win.bat

3. Compile the WASM library

Run the release build script.

tools\build_wasm_win_release.bat

4. Build the native project (optional)

If you want to debug the code, it's useful to build a native project. To do that, just use cmake to generate the project of your choice.

How to run locally?

To run the demo and the examples locally, you have to start a web server. Run npm install from the root directory, then run npm start and visit http://localhost:8080.

tkvw/occt-import-js