Unity Android Application Integration

In this article we look at how to integrate an Unity and Android Project more specifically how to add Android View and Layouts on top of exiting Unity Views.

Unity Application

When a Unity app starts, UnityPlayerProxyActivity chooses which activity to instantiate: UnityPlayerActivity or UnityPlayerNativeActivity.

All three classes—UnityPlayerProxyActivity, UnityPlayerActivity, UnityPlayerNativeActivity—are compiled into a file called UnityPlayer.jar.

It chooses which class to instantiate based on the version of Android running on the device. Support for native activities was not added to Android until Gingerbread (API level 9) and so UnityPlayerNativeActivity is only instantiated if the device is running Gingerbread or higher.Otherwise, UnityPlayerActivity is instantiated.

Both UnityPlayerActivity and UnityPlayerNativeActivity are responsible for starting the Unity game engine and therby instantiating the views and coroutines.

Let us consider the following Unity Program ,which just starts a coroutine upon initialization. The scene contains no views or camera objects in the Unity Application just a GameObject

Let us add a script to the gameobject called AndroidUnityInterface.cs The script is reponsible for running the routines on Unity as well as communicating with the android Application.

enter image description here

using UnityEngine;
using System.Collections;

public class AndroidUnityInterface : MonoBehaviour {

	// Use this for initialization
	void Start () {
	
		Debug.LogError ("Starting the Android Unity Interface");
	}
	
	// Update is called once per frame
	void Update () {

		Debug.LogError ("Update the Android Unity Interface");
	
	}
}

This script will call the Start function while initialization and Update function is called at every frame.

Unity Project Build

Build the project for the Android platform.Open the Player settings and take note of the package name that you have chosen as your “Bundle Identifier as com.example.androidunityinterface and the Android API level (e.g., 4.3 “JellyBean”), as you will reuse these settings later.

The same package name will be used while creating the android application in the below section.

If we compile and run the application,we would observe the Default Unity View and in the android Logs we would be able to observe the Debug Log statements written in the Start and Update functions.

11-15 16:46:20.276    7766-7791/? E/Unity﹕ Starting the Android Unity Interface
    (Filename: ./artifacts/generated/common/runtime/UnityEngineDebug.gen.cpp Line: 56)
11-15 16:46:20.286    7766-7791/? E/Unity﹕ Update the Android Unity Interface
    (Filename: ./artifacts/generated/common/runtime/UnityEngineDebug.gen.cpp Line: 56)
11-15 16:46:20.321    7766-7791/? E/Unity﹕ Update the Android Unity Interface

Adding Android Views on Top of Unity

With Unity Android it is possible to extend the standard UnityPlayerActivity or UnityPlayerNativeActivity class (the primary Java class for the Unity Player on Android) enabling an application to override any and all of the basic interaction between Android OS and Unity Android.

Thus by extending the UnityPlayerNativeActivity we are manually instantiating the unity game engine.

Copying Unity Files

As mentioned in the above section the UnityPlayerNative class is found in the classes.jar file in Unity. This files needs to be added to android project.

The jar file can be found in Editor\Data\PlaybackEngines\androidplayer\release\bin path in Unity Installation directory.

We need to add this classes.jar file to the project.
we also need to copy unity libraries from following path from unity installation directory Editor\Data\PlaybackEngines\androidplayer\development\libs\armeabi-v7a to libs directory of the Android project.

Let first look at Android Application just instantiating the UnityGame Engine for the application in the above section.

We will be using Android-Studio for android application development

public class MainActivity extends UnityPlayerNativeActivity  {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        final long delay = 1000;//ms
        Handler handler = new Handler();

        Runnable runnable = new Runnable() {
            public void run() {
	            //gets the root default unity view
                ViewGroup rootView = (ViewGroup) MainActivity.this.findViewById(android.R.id.content);
                rootView.setKeepScreenOn(true);
            }
        }

        getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
        
        handler.postDelayed(runnable, delay);
        
    }

}

Native Events forwarding

we need to allow native events forwarding so that events(like touch) are forwarded from unity to android.This is done by specifying the ForwardNativeEventsToDalvik setting in the manifest (must be set to true)

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.androidunityinterface" >

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:screenOrientation="landscape"
            android:label="@string/app_name"
            android:configChanges="fontScale|keyboard|keyboardHidden|locale|mnc|mcc|navigation|orientation|screenLayout|uiMode|touchscreen"
            >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
            <meta-data
                android:name="unityplayer.ForwardNativeEventsToDalvik"
                android:value="true" />
        </activity>
    </application>

</manifest>

Copying Unity Files

Use your file explorer to browse to your Unity project directory, where there is a folder called “/Temp” containing a subfolder called “/StagingArea.”

StagingArea folder contains these set of files and directories (such as /res, /assets, /bin, AndroidManifest.xml,…) similar to a typical eclipse android directory.

Copy the contents of “/assets/” and “/libs” directories to corresponding directories in the AndroidProject.

Testing The application

we can now run the android application and expect the same result as just running the unity application.

11-15 19:17:39.881      535-578/com.example.androidunityinterface E/Unity﹕ Starting the Android Unity Interface
    UnityEngine.Debug:Internal_Log(Int32, String, Object)
    UnityEngine.Debug:LogError(Object)
    AndroidUnityInterface:Start()
    (Filename: ./artifacts/generated/common/runtime/UnityEngineDebug.gen.cpp Line: 56)
11-15 19:17:39.901      535-578/com.example.androidunityinterface E/Unity﹕ Update the Android Unity Interface
    UnityEngine.Debug:Internal_Log(Int32, String, Object)
    UnityEngine.Debug:LogError(Object)
    AndroidUnityInterface:Update()
    (Filename: ./artifacts/generated/common/runtime/UnityEngineDebug.gen.cpp Line: 56)
11-15 19:17:39.966      535-578/com.example.androidunityinterface E/Unity﹕ Update the Android Unity Interface
    UnityEngine.Debug:Internal_Log(Int32, String, Object)
    UnityEngine.Debug:LogError(Object)
    AndroidUnityInterface:Update()

Adding Android on Top of Unity Views

We can now add android views on top of the unity view programatically.

First Scan the view hierarchy recursively, starting from the root view of your main activity, and find the leaf view in the hierarchy.

    private View getLeafView(View view) {
        if (view instanceof ViewGroup) {
            ViewGroup vg = (ViewGroup)view;
            for (int i = 0; i < vg.getChildCount(); ++i) {
                View chview = vg.getChildAt(i);
                View result = getLeafView(chview);
                if (result != null)
                    return result;
            }
            return null;
        }
        else {

            Log.e("ZZ","Found leaf view");
            return view;
        }
    }

When you find the leaf view, get the parent of that view. Call this view leafParent for ease of reference.

Add your custom views as a child of the leafParent view, for example, a layout inflated from XML.

public class MainActivity extends UnityPlayerNativeActivity  {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        final long delay = 1000;//ms
        Handler handler = new Handler();

        Runnable runnable = new Runnable() {
            public void run() {
                ViewGroup rootView = (ViewGroup) MainActivity.this.findViewById(android.R.id.content);
                rootView.setKeepScreenOn(true);

                //get the topmost view
                View topMostView = getLeafView(rootView);
                // let's add a sibling to the leaf view
                ViewGroup leafParent = (ViewGroup)topMostView.getParent();

                //inflate the android view to be added
                View view = getLayoutInflater().inflate(R.layout.activity_main, null, false);
                view.setKeepScreenOn(true);

                //add the android view on top of unity view
                leafParent.addView(view, new LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT));
            }
        };

        getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
        handler.postDelayed(runnable, delay);

    }
    

Final Applicaiton

The “hello World” text is part of the android layout

enter image description here

The files for unity and android project can be found in the below bitbucket repository https://bitbucket.org/pi19404/unityandroidproject/

References

http://docs.unity3d.com/Manual/PluginsForAndroid.html
https://developer.vuforia.com/library/articles/Solution/How-To-Add-Views-Over-Unity-for-Android

Unity Android Application Integration