Set up v2 Native C or C++

This document helps you set up your C++ project for v2 Native C or C++ and verify the authentication service.

Before you start

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

App prerequisites

Make sure that your app's build file uses the following values:

A minSdkVersion of 19 or higher
A compileSdkVersion of 28 or higher

Set up your game project

Complete the following steps to set up your game project.

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 v2 Native SDK (beta):
- com.google.android.gms:play-services-games-v2-native-c:21.0.0-beta1

Here's an example:

  android {
    ...
    buildFeatures {
      prefab true
    }
    ...
  }
  dependencies {
    ...
    implementation "com.google.android.gms:play-services-games-v2-native-c:21.0.0-beta1"
  }

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 AndroidManifest.xml

To define your Play Games Services project ID in your AndroidManifest.xml file, add the following lines:

<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, the game displays a sign-in prompt or a successful sign-in banner.

Get the player ID

Your game can access player information for an authenticated player by retrieving their player ID. You can retrieve a player ID by calling the GetPlayerId function, as 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 authenticated.

Game server authorization

Once a player successfully authenticates 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 authenticated player. You can retrieve the server authorization code by calling the PgsGamesSignInClient_requestServerSideAccess function.

For more information, see the server access guide.