Android

Technical information

Flax is compiled for Linux platform using Android NDK and build with Android SDK. Supported are system version Android 7 or newer (platform API level 24). Flax uses Vulkan for rendering graphics on Android (min. Vulkan 1.0).

Android Setup

Follow these steps to setup your development PC for building game for Android platform. In case of problems, please follow official documentation of Android platform.

Install Open JDK (https://jdk.java.net/15 and set JAVA_HOME to jdk root folder)
Download and install Android Studio (https://developer.android.com/studio)
Open Android Studio and complete the setup (install it to the default location or custom one and set ANDROID_SDK to SDK root folder)
Install NDK (via Android SDK side-by-side or manually via https://developer.android.com/ndk/downloads/index.html and set ANDROID_NDK to install location)
(when using Flax from Launcher) Install Android Platform Tools for Editor installation via Flax Launcher

Build options

See Game Cooker window.

Property

Description

Output

The builded game output folder (relative to the project).

Show Output

If checked, after building the output folder will be shown in an Explorer.

Configuration Mode

Game building mode. Possible options:

Option	Description
Release	The release build ready for shipment.
Debug	The debug build for testing and profiling. Most of the code optimizations are disabled for the best debugging experience.
Development	The development build for testing and profiling but is more optimized for runtime than Debug build.

Platform settings

See Android Platform Settings asset.

Property	Description
Package Name	The application package name (eg. `com.company.product`). Custom tokens: `${PROJECT_NAME}`, `${COMPANY_NAME}`.
Permissions	The application permissions list (eg. `android.media.action.IMAGE_CAPTURE`). Added to the generated manifest file.
Override Icon	Custom icon texture to use for the application (overrides the default one).

C++ Debugging

Install C++ Android development tools via Visual Studio Installer
Build game for android to .apk and install it on the device
Regenerate scripts projects files
Set startup project to one named Android
Edit that project properties: Debugging -> Package To Launch set your apk path in Package to Launch and set Additional Symbol Search Paths to game cooker output location folder with libFlaxGame.so file for the target arch ARM64 (<output>/app/jniLibs/arm64-v8a)
Run the Android project with a debugger on an device

Optionally you can install apk manually and attach to it with

Use Debug -> Attach to Android Process
Once debugger is attached you can insert breakpoints and debug the game code

Android adb logs collecting

Debug and Devlopment builds are using low-level Android logger to output engine and game logs directly to the adb. Use .\adb.exe -d logcat Flax:I *:S to listen for game logs on device.

Vulkan debugging

Build Debug build
Copy libVkLayer_khronos_validation.so (optionally other validation libs) from NDK/sources/third_party/vulkan/src/build-android/jniLibs/arm64-v8a to output Gradle project libs folder (<output>/app/jniLibs/arm64-v8a)
Monitor adb output log with Vulkan Validation layer logs
Note that game performance will be lower (esp. CPU) due to additional validation of the GPU commands

Additional notes

Flax exposes Gamepad for Android device at index 0 which can be used to vibrate the device or read the Back key pressed by the user during gameplay
To enable device vibrations add android.permission.VIBRATE to the permissions list in Android Platform Settings asset
To enable device network state reading add android.permission.ACCESS_NETWORK_STATE to the permissions list in Android Platform Settings asset