Get started with Play Games Services for C and C++

This guide describes how to set up a native C or C++ game project to use the Play Games Services v2 Native SDK and integrate the Sign-in service. Sign-in integration is required in order to integrate other Play Games Services features into your game and to integrate Play Games Services into your backend game server.

Supported features

The Play Games Services v2 Native SDK is in beta and only supports the Sign-in service. It doesn't yet support other Play Games Services features.

API reference documentation

The header files for the SDK contain reference documentation for the APIs. The header files are located in the include folder in the SDK files, which are available after you sync your project with SDK repository.

Requirements

A game project that uses native C or C++ as the primary programming language.
Your game project and development environment must have the Gradle build system set up.

Before you start

You must set up Play Games Services in Google Play Console.

Set up your game project

Complete the following steps to set up your game project.

Update CMakeLists.txt

In your CMakeLists.txt file, add the following code:

  find_package(com.google.android.gms.games.v2.c REQUIRED CONFIG)

  // link games_static for -DANDROID_STL=c++_static or default
  // link games_shared for -DANDROID_STL=c++_shared
  target_link_libraries(
    app PUBLIC com.google.android.gms.games.v2.c::games_static)

Update build.gradle

In your app-level build.gradle file do the following:

Make sure the prefab build feature is enabled.
Add the dependency for the Play Games Services v2 Native SDK:
- com.google.android.gms:play-services-games-v2-native-c:17.0.0-beta1

Here's an example:

  android {
    ...
    buildFeatures {
      prefab true
    }
    ...
  }
  dependencies {
    ...
    implementation "com.google.android.gms:play-services-games-v2-native-c:17.0.0-beta1"
  }

Update AndroidManifest.xml

In your AndroidManifest.xml file, define your Play Games Services project ID. You can do so by adding the following lines to the file:

<manifest>
  <application>
    <meta-data android:name="com.google.android.gms.games.APP_ID"
               android:value="@string/game_services_project_id"/>
  </application>
</manifest>

Create a string resource for your project ID. This allows your game to access the ID at build time. To create the resource, create the file project_root/app/src/main/res/values/games-ids.xml, and add the following:
```
<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="game_services_project_id"
            translatable="false">add your Project ID here</string>
</resources>
```
Build and test your game. If successful, when you launch your game it displays a sign-in prompt or a successful sign-in banner.

Get the player ID

Your game can access player information for a signed in player by retrieving their player ID. You can retrieve a player ID by calling the GetPlayerID function, which is demonstrated in the following example.

#include <assert.h>
#include "gni/gni.h"
#include "gni/gni_task.h"
#include "pgs/pgs_play_games.h"
#include "pgs/pgs_players_client.h"

// A callback for a GniTask returned from PgsPlayersClient_getCurrentPlayerId.
void OnGetCurrentPlayerIdCompleteCallback(GniTask *task, void *user_data) {

   if (!GniTask_isSuccessful(task)) {
      const char *error_message = nullptr;
      GniTask_getErrorMessage(task, &error_message);

      // Log error message here.

      GniString_destroy(error_message);
      GniTask_destroy(task);
      return;
   }

   const char *result = nullptr;
   PgsPlayersClient_getCurrentPlayerId_getResult(task, &result);

   // Log player id here.

   GniString_destroy(result);
   GniTask_destroy(task);
}

// Gets the player ID.
void GetPlayerId(jobject main_activity) {
   static const PgsPlayersClient *players_client =
           PgsPlayGames_getPlayersClient(main_activity);

   GniTask *get_current_player_id_task =
           PgsPlayersClient_getCurrentPlayerId(players_client);
   assert(get_current_player_id_task != nullptr);
   GniTask_addOnCompleteCallback(get_current_player_id_task,
                                 OnGetCurrentPlayerIdCompleteCallback,
                                 nullptr);
}

// Entry point for our test app
void TestPGSNative(JNIEnv *env, jobject main_activity) {
   JavaVM *java_vm;
   env->GetJavaVM(&java_vm);

   GniCore_init(java_vm, main_activity);

   GetPlayerId(main_activity);
}

If a player declines the initial Play Games Services sign-in prompt that is automatically displayed when your game launches, they may change their mind during the game session. You can re-launch the sign-in prompt by calling PgsGamesSignInClient_signIn as long as no players are currently signed in.

Game server authorization

Once a player successfully signs into to Play Games Services, your game client can request a server authorization code that your backend game server can use to securely communicate with Play Games Services. This allows your game server to retrieve, update, and store data for the signed in player. You can retrieve the server authorization code by calling the PgsGamesSignInClient_requestServerSideAccess function.

For more information, see the server access guide.