================================================================================

 SUPERTUXKART

================================================================================



--------------------------------------------------------------------------------
 SYSTEM REQUIREMENTS
--------------------------------------------------------------------------------

To run SuperTuxKart on Android, you need a device that meets following
requirements:

- Android 4.4 or later
- Processor compatible with armv7 or x86
- GPU that supports OpenGL ES 3.0
- 1 GB RAM (STK uses ~150 MB in minimal configuration)
- 300 MB of free space on internal storage
- Touch screen or external keyboard



--------------------------------------------------------------------------------
 COMPILATION
--------------------------------------------------------------------------------

The build scripts are designed to run under linux. They may work under cygwin
after some tweaks, but atm. only linux is supported.

Dependencies list (may be incomplete):

    autoconf, automake, make, python, ant, imagemagick, cmake, vorbis-tools

Additionally some dependencies for optimize_data script:

    advancecomp, libjpeg-progs, optipng

Before compilation you must download the package with dependencies from:
https://github.com/supertuxkart/dependencies
and extract it to stk-code/lib. It contains sources of libraries that are used
in STK, but are not availiable in stk-code repository (curl, freetype, openal).

You need also Android SDK for android-19 platform (the API for Android 4.4) and
Android NDK (versions r12b and r13b have been tested).

You need to create proper "android-sdk" and "android-ndk" symlinks in the
directory with Android project, so that the compilation script will have access
to the SDK and NDK.

These paths can be also set in SDK_PATH and NDK_PATH environmental variables.

Before running the compilation, run the generate_assets script, so that
selected assets will be copied to "assets" directory, and then included in the
apk file.

You can select different karts and tracks by setting KARTS and TRACKS variables
in the generate_assets.sh script at the beginning of file.

When you are creating the assets directory manually, note that the
directories.txt file is urgently needed and it is used by the application for
extracting assets.

If the assets directory is already prepared, you can run "./make.sh" command to
build the project and create an apk file. Note that all arguments are passed to
the make command, so that you can run "./make.sh -j5" for multi-threaded build.

If you want to prepare a package for particular architecture, you can choose it
by setting the COMPILE_ARCH environmental variable. At this stage, supported
architectures are "armv7", "x86" and "aarch64". The default is "armv7".

You can choose build type by setting BUILD_TYPE environment variable to "debug"
or "release". The default is debug build. Note that if you choose release build,
you have to manually sign the apk with your key and run zipalign.

Basically if all dependencies are installed in the system, it should be enough
to just run:

    export SDK_PATH=/path/to/your/android/sdk
    export NDK_PATH=/path/to/your/android/ndk
    ./generate_assets.sh
    ./make.sh -j5



--------------------------------------------------------------------------------
 RELEASE BUILD
--------------------------------------------------------------------------------

Making a release build is similar to typical compilation, but there are few
additional things to do. 

You have to change version numbers. This is important, because assets manager
in STK checks these numbers and detects if already extracted data files are
up to date. So that when you will install new STK version, this will force new 
data extraction automatically.

So that you have to:

1. Change "data/supertuxkart.git" to "data/supertuxkart.VERSION_NUMBER"

2. Open "src/utils/constants.cpp" and change:

    const char STK_VERSION[] = "git";
      
   to
    
    const char STK_VERSION[] = "VERSION_NUMBER";
      
   where "VERSION_NUMBER" is for example "0.9.3" or "git20170409" or whatever.
    
3. You can also update these lines in "android/AndroidManifest.xml":
    android:versionCode="1"
    android:versionName="1.0"


Before compilation you have to set:

    export BUILD_TYPE=release

and then you make standard compilation with:

    ./generate_assets.sh
    ./make.sh -j5
    

The compiled apk is unsigned, so you have to sign it with your key. To sign it,
you have to run:

    jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 -keystore \
        my-release-key.keystore SuperTuxKart-release-unsigned.apk alias_name
        
and then:

    zipalign -v 4 SuperTuxKart-release-unsigned.apk SuperTuxKart-release.apk



--------------------------------------------------------------------------------
 KNOWN ISSUES
--------------------------------------------------------------------------------

1.  It's not possible to compile STK for Android < 4.4 due to missing GLES 3.0
    functions. It is technically possible to do - check GLES context version, 
    load OpenGL functions dynamically using EGL, and if they are not loaded 
    properly, then fallback to GLES 2.0.

2.  It never ocurred for me, but it's possible that EGL context is lost in some
    cases. SuperTuxKart is not designed to re-create all textures at any moment,
    so this is a "Wontfix", at least for now.

3.  We use "exit(0)" at the end of main function. We shouldn't do it and we
    should just return from the main function. But STK uses some global
    variables and their values are remembered when the game is restarted. We
    should properly clear them or re-initialize on startup. Using the "exit(0)"
    is not-that-bad workaround, but it may cause a crash on exit sometimes.
    It seems to affect only Android 5.0. More information about the crash:
    https://code.google.com/p/android/issues/detail?id=160824

4.  STK crashes on Qualcomm with Adreno 305 when trying to draw menu interface.
    Backtrace shows glDrawElements function, and internally crashed in vbo
    allocation.

5.  STK crashes on startup on some devices when aarch64 build is made using
    Android r13 NDK. The r13 version has rather big modifications (it uses clang
    instead of gcc by default). This is probably a bug in NDK/compiler/OS, but
    for this reason using NDK r12 for 64-bit arm compilation is preferred.

6.  Angelscript doesn't have full support for aarch64 builds, so that scripting
    won't work on this platform.
    
7.  Turning left/right using accelerometer is available, but at this stage the
    default screen orientation is not automatically detected and user must 
    manually choose if he needs "phone" or "tablet" accelerometer.
