How to start to contribute to Babylon.js

How to start


Development Ecosystem in Web is becoming more and more difficult to chose due to the diversity of tools and Frameworks. If you want to get started on BJS, we chose to support a set of tools to simplify your first steps with it. This can also be use on a daily basis for your contribution development.

This document will introduce everything from the tools installation to debugging in BJS. Thid is meant to be OS agnostic to allow developping the same way on Windows, Mac and Linux.


Git Client

If you do not already have a git client, you can install one from Git.

Hint: if you are developping on Windows, I would recommand using cmder as your command line host (the full install is worth it and embed a git client).


Once done, you can open a command line and configure git globally:

git config --global "John Doe"
git config --global

NodeJS and NPM

The second step is to install nodejs and its package manager. This will be your best friends and the platform helping achieving a X-platform dev experience:

Typescript and Gulp

Once both git and npm are installed in your environment, please install in global the both major BJS dev dependencies by launching those command lines:

  1. npm install -g typescript
  2. npm install -g gulp

They are respectively for dealing with the Typescript language and the build tools used in the project.

Hint: if you are developping on Windows, I would recommand using cmder as your command line host (the full install is worth it).

Visual Studio Code

TRying to be Opens source and OS agnostic, we chose to support VSCode which offer the quickest approach to get started. For the ones amongst you with already another choice, it is worth giving it a try and see what it brings as the heavy integration has been managed for you.

You can install VSCode from their site:

Once install, a few pluggins will help you having the best experience. You can search for them in the extension tab (Ctrl+Shift+d):

  1. Debugger for Chrome (also installing chrome will help but I guess this is already done)
  2. Shader language support for VS Code (syntax highlighting ang autocompletion in glsl shader)

Finally, I would recommand adding a few shortcuts to your environment. Follow the guide:

  1. To configure keyboard shortcuts the way you want, go to the menu under File > Preferences > Keyboard Shortcuts. (Code > Preferences > Keyboard Shortcuts on Mac)
  2. In the left side, add:
    // Place your key bindings in this file to overwrite the defaults
    { "key": "ctrl+shift+alt+s",         "command": "workbench.action.files.saveFiles" },
    { "key": "ctrl+shift+alt+k",         "command": "workbench.action.tasks.terminate" },
    { "key": "ctrl+shift+alt+t",         "command": "workbench.action.tasks.test" },
    { "key": "ctrl+shift+alt+l",         "command": "workbench.action.tasks.showLog" },
    { "key": "ctrl+shift+alt+r",         "command": "workbench.action.tasks.runTask" }

This will make the main commands quicker to access. Do not hesitate to adapt the bindings to your Preferences.



You are now all setup, and only a few steps from debugging. You now need to clone the project from github. Open a command line, move to the folder that will contain bjs and type:

git clone

You could clone your own fork of babylon in the same way by using its own git repository url:

git clone {yourrepo}
git remote add upstream

Adding the upstream will help syncing back your fork.

Then navigate to the BJS folder and install the BJS required node modules through npm:

cd BabylonJS/Tools/Gulp
npm install

You are good to go !!!


Open VSCode on the newly created BabylonJS folder and launch the test task. To do so, 3 solutions:

  1. Use the shortcut to run a task (Ctrl+Shift+p) and begin to type test. You should be on run test task, so hit enter.
  2. Use the shortcut you previously bind to the command in your keyboard bindings (default is Ctrl+Alf+Shift+t)
  3. Open a terminal on Tools/Gulp and run gulp run

This has been hijacked for your convenience and will watch all the files you are modifying as well as web serve the files for development purpose. As you noticed in the VSCode installation you can easily hook it to a keyboard shortcut.

Once the task is launched you can kill it by repsectively:

  1. Use the shortcut to run a task (Ctrl+Shift+p) and begin to type terminate. You should be on Terminate Running Task task, so hit enter.
  2. Use the shortcut you previously bind to the command in your keyboard bindings (default is Ctrl+Alf+Shift+k)
  3. In the terminal press Ctrl+c

In the VSCode debug tab, chose the section you want to debug and launch the debugger (the test task needs to be running).

This will debug alls the TS and js in chrome and stop on your breakpoints setup in those files in VSCode. This debugs all the code from src, materialsLibrary, procceduralTexturesLibrary, postprocessLibrary...

Hint: If another chrome sesssion already runs in remote debug on port 9222 the debugger will fail to attach as the port is already open. You will have to close the other remote debug first.

The main entry points in BJS are:

  1. Playground: http://localhost:1338/Playground/index-local.html
  2. Materials Library: http://localhost:1338/materialsLibrary/index.html
  3. Post Process Library: http://localhost:1338/postProcessLibrary/index.html
  4. Procedural Textures Library: http://localhost:1338/proceduralTexturesLibrary/index.html
  5. Inspector: http://localhost:1338/inspector/index.html
  6. Local Dev: http://localhost:1338/localDev/index.html

All of those allows debugging the source code of bjs directly from typescript.


If you wish testing the fully compiled version instead of independant files simply append ?dist=true in the different urls.

You could also test against the minified version by choosing ?dist=min. this will work on all the referenced URLs.

Edit Code

Once the test task (gulp run) has been launched through gulp or VSCode, any TS or shader file save will automatically rebuild the associated js. Simply reload your browser to see the changes in effect and begin to debug your new code.

Hint: You may need to refresh the code before adding back a new breakpoint.

Local Dev

In order to simplify the quick testing and development. You can copy paste playgrounds code in the devLocal/src/index.js file . The entire devLocal/src folder is git ignored and is meant to be your local test folder.

You can launch it through: Local Dev: http://localhost:1338/localDev/index.html

From there you can easily add breakpoint in your playground js or the BJS ts files for debugging.

Adding in the url ?dist=true or ?dist=min will help testing against the built files.

As using only one test file is annoying, feel free to add index.1.js, index.2.js... and so on. In VSCode, copy pasting the file in the same folder results in creating the next available slot in the folder e.g. copy pasting index.1.js will create index.2.js.

To launch index.{number}.js simply append in the url sample={number} so for launching index.3.js against the unminified released files, use: http://localhost:1338/localDev/index.html?dist=true&sample=3

This should help playing andd debugging locally.


The main gulpfile in Tools/Gulp contains a lot of helpfull tasks. So first open a terminal (Ctrl+`) in VScode or your favorite terminal. Navigate to the Tools/Gulp folder and you are ready to run the following commands.

  • gulp run launches all the watchers and a web server (this is map to the test command in VSCode)
  • gulp webserver launches the webserver only.
  • gulp watch launches the watchers only.
  • gulp typescript-all generates all the distribution files in the dist/preview release folder (This is map to the build command in VSCode Ctrl+Shift+b).
  • gulp typescript generates the BJS distribution files.
  • gulp typescript-libraries generates all the library (materials, procedural textures...) files in the dist/preview release folder.
  • gulp loaders generates all the loaders files in the dist/preview release folder.
  • gulp serializers generates all the serializers files in the dist/preview release folder.
  • gulp materialsLibrary generates all the materials files in the dist/preview release folder.
  • gulp proceduralTexturesLibrary generates all the procedural textures files in the dist/preview release folder.
  • gulp postProcessesLibrary generates all the post processes files in the dist/preview release folder.
  • gulp canvas2D generates the canvas2D files in the dist/preview release folder.
  • gulp inspector generates the inspector files in the dist/preview release folder.
  • gulp deployLocalDev regenerates your localDev/src/index.js from the template.
  • gulp build-custom will generate your own version of babylon.js. You can specify which modules you want with custom.config.json in /Tools/Gulp folder.