This article helps you to get started on software development with the Doomsday Engine.


====== Before you begin ======

It is important to understand, that Doomsday is an open source project.  Doomsday is licensed under the [[http://www.gnu.org/licenses/gpl.html|GNU GPL v2 or later]] license.

To further that goal, we ask that all contributions use the following license:
  * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, see <http://www.gnu.org/licenses/>

If you do not wish to use the [[http://www.gnu.org/licenses/gpl.html|GPL]] or a compatible license like the [[http://www.opensource.org/licenses/mit-license.php|MIT]], [[http://www.opensource.org/licenses/bsd-license.php|New BSD]] or [[http://www.gnu.org/licenses/lgpl.html|LGPL]], then we can't accept your contribution.


===== Requirements =====


Check that Doomsday's [[requirements]] are fulfilled.


====== Tools needed ======


^ Tool^ Windows^ Mac OS X^ Ubuntu |
| **Git**| [[http://code.google.com/p/tortoisegit/|TortoiseGit]] is a nice Git client for Windows. It integrates with the Windows shell.| Git should be installed along with Xcode, but you can also get it from [[http://www.macports.org/|MacPorts]] or [[http://mxcl.github.com/homebrew/|Homebrew (Intel-only)]].| Available as a package (see distro). |
| **qmake**| [[http://qt.nokia.com|Qt web site]]| qt4-qmake, libqt4-dev |
| **Qt Creator** (optional)| [[http://qt.nokia.com|Qt web site]]| qtcreator |
| **Other tools**| | | [[build_tools_for_unix]] |



====== Accessing the deng source code repository ======


The deng source code is stored in a [[http://github.com/skyjake/Doomsday-Engine|Git repository on GitHub]]. You can browse the contents of the repository by visiting that link.


===== About Git =====

Git is an advanced distributed version control system. Before you do anything else, you should familiarize yourself with its basic functionality and operating principles. These should get you started:
  *  [[http://git-scm.com/documentation|Git documentation]]: tutorial, introduction for SVN users, user's manual, etc.
  *  [[http://www.youtube.com/watch?v=4XpnKHJAok8|Linus Torvard's talk about Git at Google]]


===== Setting up a working copy =====

To get a copy of the Doomsday source files to your own computer, you will first need to set up your working copy of the [[git_repository|deng repository]]. With Git being a distributed version control system, every working copy is actually a full, independent copy of the entire repository. Once you have your working copy set up, it will be configured to fetch changes from the GitHub Doomsday-Engine repository.

The first thing you will need to is to clone the deng repository:
  git clone https://github.com/skyjake/Doomsday-Engine.git //name-of-your-working-copy//

This will download the full repository (about 200MB) from GitHub, so it may take a while.

Next, you should make sure your repository configuration is good. To see all your Git configuration settings, type:
  git config -l

Your master branch should be tracking //origin//'s (= the GitHub repository) master branch:
  branch.master.remote=origin
  branch.master.merge=refs/heads/master
  remote.origin.url=https://github.com/skyjake/Doomsday-Engine.git
  remote.origin.fetch=+refs/heads/*:refs/remotes/origin/*

You may find it convenient to set a default branch for pulling changes:
  git config pull.default tracking

The options //user.name// and //user.email// should be set if you are going to commit changes to your repository.
  user.name=yourname
  user.email=your.email@some.domain


===== Getting new changes =====

To synchronize your copy of the repository with the origin, use the following command:
  git pull

This will fetch the new changes from the deng repository and merge them to your working copy.


===== Switching to another branch =====

Say you want to work on another branch, e.g., stable-1.10. You will first need to create a local branch that tracks the changes of the stable-1.10 branch in the deng repository:
  git checkout -t -b stable-1.10 origin/stable-1.10

This will also automatically switch to the new branch. In the config you now see:
  branch.stable-1.10.remote=origin
  branch.stable-1.10.merge=refs/heads/stable-1.10

This means your stable-1.10 is tracking the one in the //origin// repository.

Now you can switch between your branches with:
  git checkout master
  git checkout stable-1.10


====== Building Doomsday ======


//See:// [[compilation]]


====== See also ======

  *  [[deng_team]]
  *  [[developer_guidelines]]
  *  [[api_documentation]]