Integrating Unity 3D game engine within an Android App

This project covers the process of integrating a game made with Unity within a native Android Application.

Objective

Integrate a Unity Game within an Android App, and establish a way for Communication / Data Transfer between the two, i.e.,

1. From the Android App, Start the game and Send an initial score to Unity.
2. Receive the score in Unity. Play the game and increment the score. Send the final score back to Android.
3. Back in Android, Get the score from Unity and finally display it.

Getting Started

Unity

I have made a simple game using Unity, in which the score increments on clicking the TAP button. On clicking the Finish button, the game ends. Then I exported the project using Gradle.

Android Studio

I then opened this project using Android Studio (Import Gradle Project). You can either convert this project into an Android Archive Library (AAR) and import it in your own Android Studio project or you can modify this project itself. I chose the latter option for this project. Unity creates the UnityPlayerActivity, containing the UnityPlayer, in Android. This class is used for all communications with Unity. I added more Activities to the Project, to execute the complete flow.

For more info: Detailed Guide to Embed Unity into Android

Communication / Data Transfer

1. Android (Java) -> Unity (C#)

In Android, start the UnityPlayerActivity from your Activity with an Intent and add data to this intent using putExtra

Intent intent = new Intent(this, UnityPlayerActivity.class);
intent.putExtra("arguments", 50);
startActivity(intent);

In Unity, retrieve the data from the Intent as shown below

int tap_count;

void Start () {
	AndroidJavaClass UnityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer"); 
	AndroidJavaObject currentActivity = UnityPlayer.GetStatic<AndroidJavaObject>	("currentActivity");

	AndroidJavaObject intent = currentActivity.Call<AndroidJavaObject>("getIntent");
	bool hasExtra = intent.Call<bool> ("hasExtra", "arguments");

	if (hasExtra) {
		AndroidJavaObject extras = intent.Call<AndroidJavaObject> ("getExtras");
		tap_count = extras.Call<int> ("getInt", "arguments");
	}
}

2. Unity (C#) -> Android (Java)

In Android, create a method in UnityPlayerActivity to receive data from Unity. This method can be directly called from Unity as shown in the next section

public void onGameFinish(int score) {
	Intent resultIntent = new Intent(this, ResultActivity.class);
    resultIntent.putExtra("score", score);
    startActivity(resultIntent);
}

In Unity, call the method defined in the UnityPlayerActivity with the arguments

currentActivity.Call("onGameFinish", tap_count);

Built With

• Unity 5.6.3
• Android Studio 2.3.3

License

This project is licensed under the MIT License - see the LICENSE file for details