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Contributor's Guide

Scott Hunter edited this page · 102 revisions

We are a community that encourages contributions. Join us. Here's how.

Get Started

Get the Code

Short version:

  • No commit access? Fork and clone cesium.
  • Commit access? Clone cesium and make all changes in a branch.


  • Setup Git if it isn't already (link).
    • Make sure your SSH keys are configured (linux | mac | windows).
    • Double-check your settings for name and email: git config --get-regexp user.*.
    • Recommended Git settings:
      • git config --global push.default simple - when running git push, only push the current branch (default in Git 2.0).
      • git config --global pull.rebase preserve - when pulling remote changes, rebase your local changes on top of the remote changes, to avoid unnecessary merge commits.
      • git config --global fetch.prune true - when fetching remote changes, remove any remote branches that no longer exist on the remote.
  • Have commit access to cesium?
    • No
      • Fork cesium.
      • Create a local repo of your fork, e.g., git clone
    • Yes
      • Create a local cesium repo, e.g., git clone
      • Make changes in a branch, e.g., git checkout -b myFeature.

Build the Code


  • Install Java on your system.
  • Install Node.js on your system.

From the root Cesium directory, run:

./Tools/apache-ant-1.8.2/bin/ant combine generateDocumentation
node server.js

Then browse to http://localhost:8080/.


  • Cesium uses Ant for builds. Ant is included in the Cesium repo, but it requires that Java be installed.
  • Node.js is also required by the build.
  • In the future, build functionality will move to Node.js and the need for Java will be removed.

For a default developer build, run Ant from the root Cesium directory:

./Tools/apache-ant-1.8.2/bin/ant build

To generate HTML documentation, run:

./Tools/apache-ant-1.8.2/bin/ant generateDocumentation

To run the HTTP server for testing, run:

node server.js

To allow other machines to connect to your HTTP server for testing, run:

node server.js --public

For all build options, see Build Targets below.

Set up Eclipse

We encourage contributors to use their IDE of choice, but many of us use Eclipse. Here's how we set it up.

  • Install Java if it isn't already.
  • Download the Eclipse IDE for Java Developers. Extract to a directory of your choice. Run it.

  • Install additional Eclipse components: JavaScript Development Tools and Eclipse Web Developer Tools.

    • Help - Install New Software. Work with: select Mars from the list.
    • Expand Programming Languages, check JavaScript Development Tools.
    • Expand Web, XML, Java EE and OSGi Enterprise Development, check Eclipse Web Developer Tools.
    • Next, Next, Accept, Finish, wait, No (we have more to install).

The Java Development Tools installation dialog

  • Install the JSHint plugin:
    • Help - Install New Software. Work with:
    • Check JSHint. Next, Next, Accept, Finish, wait, OK, wait, Restart.

The JSHint installation dialog

  • Run Eclipse. Close the Welcome page.

  • Window - Preferences:

    • General - Editors - Text Editors. Check Insert spaces for tabs. Apply.
    • Web - CSS Files - Editor. Switch the radio button to "Indent using spaces". Change Indentation size to 4. Apply.
    • Web - HTML Files - Editor. Switch the radio button to "Indent using spaces". Change Indentation size to 4. OK.

Configuring "Insert spaces for tabs"

  • Import Cesium into your workspace: File - Import, General - Existing Projects into Workspace, Next. Fill in the path to the root Cesium directory, Finish.

  • Click the "Open Perspective" button in the upper right and select JavaScript. You can then right-click on the Java perspective and close it.

  • Window - Show View - Console.

Also consider the Optional Eclipse Configuration options below.

Next Steps

At this point you are ready to contribute. Continue reading below for more details on the developer setup, or read about Cesium's architecture; check out the roadmap; join the forum; and start hacking.

Become an Expert

This section has additional information on our development tools.

Build Targets

The following targets can be built:

  • build - A fast, developer-oriented build that prepares the source tree for use as standard Asynchronous Module Definition (AMD) modules, suitable for running tests and most examples (some Sandcastle examples require running combine). This runs automatically when saving files in Eclipse.
  • combine - Runs build, plus uses Node.js to run the RequireJS optimizer to combine Cesium and the Almond AMD loader to produce all-in-one files in the Build/Cesium directory that expose the entire Cesium API attached to a single global Cesium object. This version is useful if you don't want to use the modules directly with a standard AMD loader.
  • minify - Runs combine, plus minifies Cesium.js using UglifyJS2 for a smaller deployable file.
  • combineRelease - Runs combine, plus uses the optimizer to remove debugging code that validates function input and throws DeveloperErrors.
  • minifyRelease - Runs minify, and removes debugging code.
  • buildApps - Builds the example applications (such as Cesium Viewer) to produce self-contained, minified, deployable versions in the Build directory.
  • generateDocumentation - Generates HTML documentation in Build/Documentation using JSDoc 3. This step requires npm install to be run first.
  • release - A full release build that creates a shippable product, including building apps and generating documentation.
  • instrumentForCoverage - Runs JSCoverage on the source tree to allow running tests with coverage information. Use the link in index.html. Currently Windows only.
  • jsHint - Runs JSHint on the entire source tree. If you use Eclipse, see below for how to run JSHint automatically as you develop.
  • runServer - Launches a Node.js HTTP server on http://localhost:8080/ for easy access to the tests, examples, and documentation. This also provides proxying for tile server providers that don't yet support CORS for retrieving tiles, which is required for use as textures. To change the port, pass -DrunServer.port=X, where X is the desired port.
    • You can also run the server by running node server.js. Pass --help for usage instructions.
  • runPublicServer - The same as runServer with the -DrunServer.public=true argument to allow for external connections.
  • makeZipFile - Builds a zip file containing all release files. This includes the source tree (suitable for use from an AMD-aware application), plus the combined and minified Cesium.js files, the generated documentation, the test suite, and the example applications (in both built and source form).
  • clean - Removes all generated build artifacts.
  • cloc - Runs CLOC to count the lines of code on the Source and Specs directories. This requires Perl to execute.
  • sortRequires - Alphabetically sorts the list of required modules in every js file.

Specify the target(s) at the command line:

./Tools/apache-ant-1.8.2/bin/ant [target-name] [another-target-name] ...

For example, to run an un-minified build and generate the documentation:

./Tools/apache-ant-1.8.2/bin/ant combine generateDocumentation

Optional Eclipse Configuration

These steps are optional depending on your preference.

GLSL Plugin

If you edit WebGL shader files (.glsl) with Eclipse, install GLShaders for GLSL syntax highlighting. First exit Eclipse, then download GLShaders and extract into Eclipse's dropins directory.

The Eclipse dropins directory


Most of us use Git from the command-line, but there is also Eclipse integration:

  • Window - Preferences: Team - Git - Configuration

    • Verify Location in User Settings tab is set to .gitconfig in the default repository directory.
    • Verify Location in Systems Settings tab is set to {Installed/Git/Location}/etc/gitconfig.
  • Right click on Cesium in the Script Explorer. Team - Share project. Select Git, Next. Check Use or create repository in parent directory of project. Finish.

Eclipse Tips

  • Use Ctrl-Shift-R to search and open files in the workspace.

The Open Resource dialog

  • Use Ctrl-Shift-F to auto format selected code.

Test Tips

  • To debug an individual test (spec), open the browser's debugger, e.g., Ctrl-Shift-I in Chrome, and click debug to the far right of the test.

Then, to step into the test, step into stepIntoThis()


Contribute Code


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