Get Started with Play Games Services for C++ on Android

Before you begin

This developer guide will show you how to compile and run a C++ game on Android that uses the Google Play Game services API. Before you begin, download and configure the following requirements:

This developer guide uses the Android Native Development Kit (NDK). If you are unfamiliar with the NDK, refer to the NDK documentation and samples before continuing.

Step 1: Set up your environment

  1. Download the Android SDK and the Android NDK and extract them to your machine. In your environment, set SDK_ROOT to the location of your Android SDK folder and NDK_ROOT to the location of your Android NDK folder.
  2. Download the C++ sample games. This developer guide refers to the location of the samples on your machine as SAMPLES_DIR.
  3. Download the Google Play Games services C++ SDK. Extract the SDK onto your development machine. In your environment, set the variable NDK_MODULE_PATH to point to the directory above the gpg-cpp-sdk directory. You should have the following directory structure:
  4. Open Eclipse. If you have not already done so, tell Eclipse where you installed the NDK by clicking Preferences > Android > NDK.
  5. Import the Google Play services library project into your Eclipse workspace.

    1. In Eclipse, click File > Import > Android > Existing Android Code into Workspace.
    2. Select SDK_ROOT/extras/google/google_play_services/libproject/google-play-services_lib where SDK_ROOT is the location of your Android SDK.
    3. Click Finish.
  6. Import the minimalist sample project into your Eclipse workspace.

    1. In Eclipse, click File > Import > Android > Existing Android Code into Workspace.
    2. Select SAMPLES_DIR/samples-android/minimalist.
    3. Click Finish.
  7. Right click the MinimalistActivity project and click Properties. Under Android, scroll down to the Library section and make sure the google-play-services_lib project is correctly referenced. If not, remove the reference and add it again from your workspace.

Eclipse will automatically compile the Java and Android sources of your project; however, the native code in the jni folder needs to be compiled separately. To do this manually, navigate to the jni folder and run ndk-build. Remember to do this after you make any changes inside the jni folder.

Your project should now compile, though it will not work yet. You must first configure your game in the Google Play Console.

Step 2: Set up the game in the Google Play Console

Create an entry for your game in the Google Play Console. This enables Games services for your application, and creates an OAuth 2.0 client ID, if you don't already have one.

  1. Create an entry for your game by following the steps described in Setting Up Google Play Games Services.
  2. In AndroidManifest.xml, change the package attribute of the <manifest> tag to the package name you chose when setting up the Google Play Console. You may have to fix some references throughout the project after making this change (particularly to the generated R class).
  3. Open res/values/ids.xml and place your App ID there. Note that the App ID is not the same as the client ID; it is the number next to the name of your game in the Game Details page of the Google Play Console.

Step 3: Run the sample

In order to run the sample you will need a physical Android device or an emulator with Google Play services installed:

  1. Run ndk-build to compile the native code.
  2. In Eclipse, click Run > Run As > Android Application and run the sample on your device.
  3. When the sample opens, tap anywhere on the scren. You should see a Google Play Games logo appear. If you have correctly configured your app, you will be prompted to sign in.

Optional: Building Automatically with Eclipse

The following steps show you how to configure Eclipse to automatically run ndk-build when you make changes to files in the jni folder.

  1. Right-click the MinimalistActivity project and click Properties. In the Properties window, select the Builders pane.
  2. Click New to add a new Builder and select Program then click OK.
  3. In the Name field, enter 'NDK Builder'.
  4. Under Location click Browse File System and navigate to the NDK_ROOT directory and select the ndk-build command.
  5. Under Working Directory click Browse Workspace and select the MinimalistActivity project folder.
  6. Click the Refresh tab. Make sure the Refresh resources upon completion box is checked.
  7. Select the Specific resources radio button and then click Specify Resources. In the resulting dialog, select the jni folder under MinimalActivity.
  8. Click Apply and then OK to finish creating your Builder.

Now every time you edit a file within the jni folder, Eclipse will run ndk-build and print the output to the Eclipse Console.