Game Development with Unity from an Android Point of View

Developing mobile games with Unity has become more and more popular these years, and Unity developers often need to tackle OS specific challenges.

Through this talk you will discover how to work with Unity as an Android Developer. You will see how to build Unity plugins using the JNI and Java/Kotlin, which is the most efficient way to link Unity with the Android framework.

Every Unity project can be exported as an Android Studio project with a Gradle support. You’ll also see how you can integrate Unity inside a native Android Java/Kotlin application, or how to get a full control of the build process so you can benefit from the best of both worlds.

Transcript

1. Game Development with Unity from an Android Point of View Place your screenshot here Julien Salvi .droidconGreece 19
2. Android addict since Froyo Always looking for the best IPA! You can find me at @JulienSalvi Julien Salvi Senior Android Engineer @ Innovorder
3. × Game Development on Android × Building Unity Plugins × Unity from Android Studio × What’s next?
4. 1. Game Development on Android A global overview
5. Place your screenshot here Major Game engines for Android
6. “More than 50% of new mobile games are made with unity!”
7. Place your screenshot here Trusted by many studios
8. × Available on Windows and Mac (soon on Linux) × 2D, 3D games or AR/VR apps × Fast prototyping, fast scripting × Supporting most of the 3D and 2D formats Great Asset Store! Game development on Android Building Android apps with Unity
9. × OpenGL and Vulkan support × Bridge to native platforms × Android Studio project export × Java and Kotlin support Game development on Android Building Android apps with Unity
10. 2. Building Unity Plugins Android to the rescue!
11. Building Unity plugins Game Developers with Unity × Build apps with C# scripts × Control the rendering pipeline × Cross-platform shader compilation Bring the best experience at a high frame rate!
12. For our fellow Unity developers
13. “Building Plugins for Unity” 13
14. × Build your plugin using Java/Kotlin or C/C++ × Android plugins might be: .jar, .aar or .so × Add Java or Kotlin classes directly into your Unity Project Build an Android Plugin for Unity
15. Android Plugin for Unity For example let us build a player plugin for Unity Call player methods from Unity
16. Unity They are best friends! Let’s eat some C# and C++! 16
17. J N I Java / Kotlin code C/C++ code Plugin
18. public class PlayerBridge { private Context ctx; public PlayerBridge(Context ctx) {} public void addSubtitles(String path) {} public void doOnMainThread(boolean playWhenReady) {} public int getTrackCount() {} } Android Plugin for Unity
19. Calling a JAVA/Kotlin object from Unity AndroidJavaObject localMediaPlayer = null; using (AndroidJavaClass javaUnityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer")) { using (currentActivity = javaUnityPlayer.GetStatic<AndroidJavaObject>("currentActivity")) { localMediaPlayer = new AndroidJavaObject("my/plugin/vr/PlayerBridge", currentActivity); if (localMediaPlayer != null) { // Do some work with your java object outside the Android UI thread localMediaPlayer.Call("addSubtitles", subtitleURL); int count = localMediaPlayer.Call<int>("getTrackCount"); currentActivity.Call("runOnUiThread", new AndroidJavaRunnable(() => { // Do some work on Android UI thread localMediaPlayer.Call("doOnMainThread", true); })); } } }
20. Function inside your plugin Define the plugin function in your Unity script extern "C" { float FooPluginFunction (); } C/C++ Plugin [DllImport ("PluginName")] private static extern float FooPluginFunction ();
21. Better performances when you call your Java plugin through the JNI Important: JVM loading jint JNI_OnLoad(JavaVM* vm, void* reserved) { JNIEnv* jni_env = 0; vm->AttachCurrentThread(&jni_env, 0); return JNI_VERSION_1_6; } Java and C/C++ Plugin
22. JNI method for calling a method in a Java class JNIEXPORT jobject JNICALL Java_com_example_NativeClass_nativeMethod(JNIEnv* env) { jclass cls_JavaClass = env->FindClass("com/your/java/Class"); // find class definition jmethodID mid_JavaClass = env->GetMethodID (cls_JavaClass, "<init>", "()V"); // find constructor method jobject obj_JavaClass = env->NewObject(cls_JavaClass, mid_JavaClass); // create object instance return env->NewGlobalRef(obj_JavaClass); // return object with a global reference } Java and C/C++ Plugin
23. static void UNITY_INTERFACE_API OnRenderEvent(int eventID) { switch((GLEvent)eventID) { case Initialize : InitMediaSurface(); break; case Shutdown : mediaSurface->Shutdown(); mediaSurface = NULL; break; case Update: mediaSurface->Update(); break; case Resize: mediaSurface->ResizeTexture(); break; } } Java and C/C++ Plugin static void UNITY_INTERFACE_API OnRenderEvent(int eventID); enum GLEvent { Initialize = 0, Shutdown = 1, Update = 2, Resize = 3 }; Sending event to the native surface
24. Set a native callback and dispatch an event to the native plugin from Unity // Set the native callback from Unity _inptr_native_callback_delegate = Marshal.GetFunctionPointerForDelegate(NativeCallback); // Native method from the plugin CINEVR_AndroidNative_SetNativeCallback(_inptr_native_callback_delegate); Java and C/C++ Plugin // Get native callback from the plugin to queue for Unity's renderer to invoke IntPtr _renderFunc = CINEVR_AndroidNative_GetRenderEventFunc(); // Dispatch the event to native plugin GL.IssuePluginEvent(_renderFunc, GLEventType.Initialize);
25. Your C++ method in your JNI plugin JNIEXPORT jstring JNICALL Java_js_NativePlugin_getHiString(JNIEnv * env, jobject obj) { return env->NewStringUTF("Hi .droidconGreece! Hope you have fun"); } C/C++ from Java or Kotlin
26. From Kotlin C/C++ from Java or Kotlin external fun getHiString(): String From Java public native String getHiString(); From Kotlin init { System.loadLibrary("sample-jni") } From Java static { System.loadLibrary("sample-jni"); }
27. × Support available from 2018.2 × Add your files in a dedicated folder in the Asset Folder × Build with Gradle only × Use the AndroidJavaObject class to call methods in your plugin Building Unity Plugins Using Java or Kotlin source files as plugins
28. × Enable Custom Gradle Templates property on the Player window × Override the generated mainTemplate.gradle file × You can also provide your own settings.gradle file Building Unity Plugins Add Gradle dependencies to your Unity project
29. 3. Unity from Android Studio Your turn Android devs!
30. That’s what we want!
31. × Export your Unity project with Gradle or IL2CPP as Build System × Enable Symlink Sources if you have Java or Kotlin source files Unity from Android Studio Exporting a Unity Project
32. × Have a full control of the build workflow × Easily add Android code × Easy library management × Modify generated code Unity from Android Studio Exporting a Unity Project
33. UnityPlayerActivity overview public class UnityPlayerActivity extends Activity { protected UnityPlayer mUnityPlayer; // don't change it, referenced from native code @Override protected void onCreate(Bundle savedInstanceState) { requestWindowFeature(Window.FEATURE_NO_TITLE); super.onCreate(savedInstanceState); getWindow().setFormat(PixelFormat.RGBX_8888); // <-- This makes xperia play happy mUnityPlayer = new UnityPlayer(this); setContentView(mUnityPlayer); mUnityPlayer.requestFocus(); } }
34. Override the UnityPlayerActivity public class OverrideExample extends UnityPlayerActivity { @Override protected String updateUnityCommandLineArguments(String cmdLine) { if (Utils.preferVulkan()) return Utils.appendCommandLineArgument(cmdLine, "-force-vulkan"); else if (Utils.preferES2()) return Utils.appendCommandLineArgument(cmdLine, "-force-gles20"); else return cmdLine; // let Unity pick the Graphics API based on PlayerSettings } }
35. 4. What’s Next? \ (•◡•) /
36. What’s next? Linux support is coming soon Better Gradle integration Better performances
37. And that’s it?
38. Of course not!
39. Unity as a LiBrary!
40. What’s next? Unity as a Library × Available with Unity 2019.3 × Add Unity content (AR/VR, 2D/3D games) directly to your Android apps × Proper library integration
42. public class MainUnityActivity extends OverrideUnityActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); goBackBtn.setOnClickListener(v -> { showMainActivity(); }); sendMsgBtn.setOnClickListener(v -> { UnitySendMessage("Cube", "ChangeColor", "yellow"); }); finishBtn.setOnClickListener(v -> { finish(); }); } } Override the OverrideUnityActivity
43. What’s next? Unity as a Library limitations × Fullscreen rendering only × Only one instance of the Unity runtime is supported × You may need to adapt your plugins to work properly
44. What’s next? Unity as a library 01 02 03 https://blogs.unity3d.com/2019/06/17/add-features-powered-by -unity-to-native-mobile-apps Unity as a Library https://forum.unity.com/threads/using-unity-as-a-library-in-nat ive-ios-android-apps.685195/ Using Unity as a library in native iOS/Android apps https://forum.unity.com/threads/integration-unity-as-a-library- in-native-android-app.685240/ Integration Unity as a library in native Android app
45. Want to know more? https://developer.android.com/game Android Game Development https://medium.com/@cinemur/73ec7e83dd5c ExoPlayer for building powerful VR players on Cardboard and GearVR https://docs.unity3d.com/Manual/PluginsForAndroid.html Building Unity Plugins for Android
46. THANKS! Have fun with Android and Unity! Any questions?