Learning AndEngine: Design and create Android games with the simple but powerful tool AndEngine

Go to http://developer.android.com/sdk/. If you are on Windows, click on the Download Eclipse ADT with the Android SDK for Windows button. If you are using a different operating system, the page should autodetect it and offer you the link for your OS. In case it doesn't detect it correctly, there is a link called VIEW ALL DOWNLOADS AND SIZES that will expand a list of available platforms. Choose the right platform for you. Be careful when choosing 32-bit or 64-bit software. If you are running a 32-bit Java on a 64-bit system, choose the 32-bit software. Accept the license agreement and save the file to your hard drive. The examples in this chapter are from the 32-bit version for Windows.

The downloaded file will be a ZIP archive called something like adt-bundle-windows-x86-20131030.zip. The filename indicates the selected platform and the date of release. To install the software, simply unpack the archive to any folder.

You should find the following in the folder where you have unpacked the archive:

First, run the SDK Manager.exe file. It might take a while to start, and it doesn't show any splash screen. You will be presented with a window similar to the one in the following screenshot:

Check for any packages that have updates available. Note that you only need the latest SDK, which at the time this book was written was SDK 19 for Android 4.4. The latest version is always bundled with the Android SDK. You should also check the Google USB Driver option.

Optionally, you can install the Android emulator system images for older Android versions. This is useful for testing. However, AndEngine can't be deployed to an Android emulator with Android versions 2.x. For now, do not install anything else but the updates and the USB driver. Install the selected packages and close the SDK manager. The installation might take a while, because the packages are downloaded from the Internet.

Now, run the Eclipse IDE. From the eclipse folder, run the eclipse.exe file. After the splash, the first thing you will see is the workspace selection window. This is shown in the following screenshot:

If you have never worked with Eclipse, note that a workspace is both a virtual space on your screen (the layout) and a directory where your projects and some metadata that Eclipse keeps about your projects are stored. Choose any directory you want, but make sure it is one with easy access. You can have multiple workspaces. If you check the Use this as the default and do not ask again checkbox, you will be working with this workspace by default and this dialog box won't appear again at the start.

After the start, close the Welcome screen and you will be presented with the Eclipse default layout. Parts of the layout can be dragged and dropped to different locations. Also, you can have different perspectives (presets of the opened windows and tabs) for each workspace. We will be using the Java perspective for most of the time but we will also use Dalvik Debug Monitor Server (DDMS) and the Debug perspective for debugging and tuning our application. The perspectives are available by navigating to Window | Open Perspective.

Stay in the Java perspective, but go to Window | Show View | Other… and search for LogCat, as shown in the following screenshot:

LogCat is a log console. The Android system has a logging system that allows developers to print categorized text messages to LogCat from their apps. This is very useful for game developers because the text output to the screen can be very limited. The ADT takes care of getting the LogCat output from the connected Android device.

The Eclipse IDE can be a bit difficult to grasp from the start. However, as a Java developer, you have probably used it before or have used a similar one. Most of the IDEs nowadays are very similar. Try to familiarize yourself with Eclipse before proceeding to the next step.

Android uses OpenGL ES to display accelerated graphics. OpenGL ES is a free API for full-function 2D and 3D graphics on embedded systems. There are several versions of OpenGL ES, namely versions 1.x, 2.x, and recently 3.x.

A repository can also contain multiple branches. Think of a branch as an alternative version of the project. AndEngine is split into three branches. The GLES1 branch uses OpenGL ES 1.0 and it is the oldest. I don't recommend using it. GLES2 is newer and GLES2-AnchorCenter is the newest. They both use OpenGL ES 2. Use the GLES2-AnchorCenter branch if you haven't used AndEngine before. The GLES2-AnchorCenter branch's biggest difference from the GLES2 branch is the fact that point [0, 0] is now in the lower-left corner of the screen. This is the same as in OpenGL and that's why it's recommended.

For the purpose of this book, we are going to exclusively use the GLES2-AnchorCenter branch.

AndEngine is split into a main project simply called AndEngine and many extensions called, for example, AndEngineMultiplayerExtension, which are dependent on the main project. Each project resides in its own repository.

For our game, we need the main AndEngine project and a 2D physics extension called AndEnginePhysicsBox2DExtension. This extension adds a very popular 2D physics simulation framework called Box2D to AndEngine. A lot of popular games use this framework.

There is also a repository called AndEngineExamples. It is not an extension but an application that includes all of the other AndEngine libraries and extensions and illustrates their use.

You can download the sources from Nicolas Gramlich's original repository at https://github.com/nicolasgramlich/.

However, there is a danger that the codes will be changed any time in the future. For that reason, I recommend to download the sources from my forked repository, which is guaranteed to work with the sources in this book.

The easiest way is to download the complete repository as a ZIP archive, which can be done with the help of the following steps:

In Eclipse, navigate to File | Import and choose Existing Projects into Workspace (under the General folder). Browse to your workspace directory. You should see two projects. Check them both and import them by clicking on the Finish button. This is shown in the following screenshot:

If you have installed the ADT bundle with Android SDK 19, you should see no errors. In case there are errors, try cleaning and building all projects again. Simply click on the Project drop-down menu in Eclipse's main menu and select the Clean… option while having the Build Automatically option checked.

It is possible that when you were installing the ADT bundle, it contained a different SDK version from 19, or maybe you are, for some other reason, using a different version. In that case, you will see messages like the following in the console:

[2014-01-14 15:36:11 - AndEngine] Unable to resolve target 'android-19'

Right-click on the project, select the Properties option, and then choose the Android option. Make sure that the Android SDK version of your choice (or simply the latest) is selected. This is shown in the following screenshot. You will probably have to clean the project to make the error disappear. We have to do this because the project was saved with SDK 19 selected. Do it for both projects.