Worldcore

Worldcore is a multi-player 3D game engine for the web, running on Croquet. It is modular, extensible, and cross-platform.

In this monorepo you will find

• the packages making up Worldcore itself
• example apps
• and tutorials

Packages

Worldcore consists of multiple packages, which all live in this repository under packages/:

• @croquet/worldcore-kernel: provides the core functionality, and re-exports all of Croquet's exports (packages/kernel)
• @croquet/worldcore-*: optional packages (packages/*)
• @croquet/worldcore: combines all of the above in a single package for convenience (packages/full)

Prerequisites:

• git https://git-scm.com/download/
• node https://nodejs.org/en/download/

We use git to manage our source code. To verify installation worked, type the command line git --version and you should see output similar to this:

git --version
=> git version 2.37.1

The exact version does not matter. Similarly for Node, which we use for our build tools:

node --version
=> v16.20.0

Preparation

We use Lerna to manage the packages in this monorepo.

Clone the Worldcore repo:

git clone https://github.com/croquet/worldcore.git

Install build tools (e.g. lerna):

cd worldcore
npm i
npx lerna bootstrap

Run and modify an example

• Execute these commands (we do not show the output here, only the commands):

  cd worldcore/tutorials/tutorial01
  npm start
  

  This command will not stop until you press ctrl-c. It will continually rebuild files as you edit them.

• Open http://localhost:1234/ in a web browser to see the "tutorial1" example app

Modify and test Worldcore packages

To test a locally modified Worldcore package, we need to make an example use the version you modified locally, rather than the released version specified in its package.json. This is the main purpose of lerna. Instead of installing packages from npm in node_modules, it will link your local version of the package into node_modules.

Assuming you did not do the lerna bootstrap step above, but used a regular npm i, you would have this structure in the node_modules/@croquet directory, containing the officially published Worldcore packages:

ls -lF tutorials/tutorial01/node_modules/\@croquet/
=> croquet/
=> worldcore/
=> worldcore-kernel/
=> worldcore-rapier/
=> worldcore-three/
=> worldcore-widget/
=> worldcore-widget2/

But if you bootstrap the repo using lerna:

npx lerna clean
npx lerna bootstrap

... then the node_modules/@croquet directory will use the local worldcore via symlink:

ls -lF tutorials/tutorial01/node_modules/\@croquet/
=> worldcore@ -> ../../../../packages/full

which in turn links to all the individual local worldcore packages

ls -lF packages/full/node_modules/@croquet
=> worldcore-kernel@ -> ../../../kernel
=> worldcore-rapier@ -> ../../../rapier
=> worldcore-three@ -> ../../../three
=> worldcore-widget@ -> ../../../widget
=> worldcore-widget2@ -> ../../../widget2

Now when you modify something in e.g. packages/three and rebuild tutorial01, it will use your version of the packages, rather than the released versions.

Publish Worldcore packages

We use lerna with "fixed" versioning, meaning each package will have the same version.

1. (NB: skip this step for a prerelease) For each modified package:

   • update CHANGELOG.md with the next release version

2. If you have updated any dependencies (e.g., of the kernel on the Croquet library), make sure all packages have the latest dependencies

    lerna clean
    lerna bootstrap
   

3. Commit everything (the next step needs a clean repo)

4. Bump the version (NB: for a prerelease, use an alternative command as explained below)

    npx lerna version --no-push
   

   This will allow you to select the next version number, and update all packages to that version, as well as their dependencies (which includes demos, examples, and tutorials, as listed in lerna.json).

   We use --no-push to get a chance to roll back if needed (undo the version commit and delete the tag).

5. Push to git

    git push
   

6. Log into npm (only needed once for each computer; requires that you have npm credentials for the Croquet organization)

    npm login
   

7. Publish to npm

    npx lerna publish from-package
   

Prereleases

For prereleases we don't update the CHANGELOG.md files, and step 4 is adjusted to specify that private packages are not to be updated, and setting a prerelease id of "alpha" or "beta":

npx lerna version --no-push --no-private --preid alpha
or
npx lerna version --no-push --no-private --preid beta

and selecting one of the pre* options from the list.

When publishing a prerelease, it will be tagged "pre" (as opposed to the default "latest") as specified in lerna.json. This will cause the prereleases to not be installed automatically, because the regular npm i command will only use the latest tag. To install the latest pre-release, people would use e.g. npm i @croquet/worldcore@pre