## Minecraft On Jetson Tk1

Call me crazy, but with an NVIDIA Jetson TK1 in my hands, the first thing I wanted to try running was Minecraft. The real Minecraft, not the "Pocket Edition" Minecraft that normally runs on ARM processors. It took me a few days to figure out how to make it happen, but I've now got it running at a very playable 25-30Hz at 1920x1080. Hopefully the instructions below can get it working for you, too.

Just to be clear, you will need to have purchased a Minecraft license to get this running. Also, this is not a simple hack. Please don't attempt this unless you have some intermediate linux knowledge and understand the commands you are running.

### Install Java

First, Minecraft requires Java. I found you must use Oracle's Java for reasonable performance--it is 10x faster than OpenJDK Java (2-3fps vs 25-30fps). Maybe OpenJDK will see this and use it to tune their implementation.

Following these webupd8 instructions to install Java worked perfectly for me:

sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
sudo apt-get install oracle-java7-installer


Then, make sure to update your JAVA_HOME directory. I put this into my .bashrc:

JAVA_HOME=/usr/lib/jvm/java-7-oracle
PATH=${PATH}:${JAVA_HOME}/bin


### Build LWJGL

Next, Minecraft requires LWJGL. Compiling it requires only one small edit to the code and I was grateful to follow in the footsteps of this developer's instructions.

These are the packages I needed installed: (Oct 2014 update--added libxt-dev)

sudo apt-get install git ant
sudo apt-get install libxcursor-dev # X cursor management library (development files)
sudo apt-get install libxxf86vm-dev # X11 XFree86 video mode extension library (development headers)
sudo apt-get install libxrandr-dev  # X11 RandR extension library (development headers)
sudo apt-get install libxt-dev      # X11 Toolkit Intrinsics library (development headers)


Get the LWJGL source from Github:

git clone https://github.com/LWJGL/lwjgl.git


Before we compile, there is a bug in the LWJGL linux build that we need to fix first. In the file platform_build/linux_ant/build.xml you need to change this line (near the top):

<property name="libs32" value="-L/usr/X11R6/lib -L/usr/X11/lib -lm -lX11 -lXext -lXcursor -lXrandr -lXxf86vm -lpthread -L${java.home}/lib/i386 -ljawt" />  to be this instead: (just changing the i386 to arm) <property name="libs32" value="-L/usr/X11R6/lib -L/usr/X11/lib -lm -lX11 -lXext -lXcursor -lXrandr -lXxf86vm -lpthread -L${java.home}/lib/arm -ljawt" />


These are some compilation flags that ant passes to gcc when compiling. There isn't any $JAVA_HOME/lib/i386 directory on Jetson. Instead the compiler needs to look in $JAVA_HOME/lib/arm. We'll just fix this locally while LWJGL works on Issue 74.

Finally, due to a different "apt" binary in both the java sdk and in /usr/bin, there needs to be something done for your path while you build with ant. The following worked for me.

cd lwjgl
env PATH=${JAVA_HOME}/bin:${PATH} ant


The above should build a libs/linux/liblwjgl.so native shared library.

### Build OpenAL

For a while, I thought this would be all I needed for LWJGL and I was confused as to why sound did not work. But, LWJGL doesn't actually build libopenal.so, it just packages up an x86 shared library. See https://github.com/LWJGL/lwjgl/tree/master/libs/linux

So, we must build OpenAL. For this, I needed to get cmake.

sudo apt-get install cmake


wget http://kcat.strangesoft.net/openal-releases/openal-soft-1.15.1.tar.bz2
tar xvjf openal-soft-1.15.1.tar.bz2
cd openal-soft-1.15.1/build/
cmake ..
make


This should create a build/libopenal.so.1.15.1 native shared library.

Now, find a convenient location to store your LWJGL and OpenAL libraries. Copy the libraries you've created to that location. Note that libopenal.so changes names to drop the version number.

For example: (adjust paths as needed)

mkdir -p ~/Minecraft/Natives
cp ~/Dev/openal-soft-1.15.1/build/libopenal.so.1.15.1 ~/Minecraft/Natives/libopenal.so
cp ~/Dev/lwjgl/libs/linux/liblwjgl.so ~/Minecraft/Natives


### Preliminary Run of Minecraft

Find the latest Linux Minecraft.jar from https://minecraft.net/download and save that in the ~/Minecraft directory. Run this via java -jar Minecraft.jar and try to start a game from the launcher window. It should download all the files necessary into the ~/.minecraft directory in order to run the latest version of Minecraft. But, it will complain when it can't find the arm native libraries. Just quit after you try to launch a game and it fails.

During this process you should see a lot of output to your terminal. One piece is the java commandline it uses to start the game from the launcher. I'm sure this commandline will change in the future, so make note of this and if you are running a version of Minecraft different than 1.7.10, you will need to adjust.

I've created a gist here that has the commandline that I'm using. (Oct 2014 update--added Version 1.8 support)

Basically, all I did was change the -Djava.library.path to point to our native libraries and add the last part of the commandline starting with --username. This last bit is not listed in the terminal output. These are additional parameters that I only found via a google search. Again, I'm sure these options will change going forward. As versions change, perhaps we can work together to maintain these commandlines via the gist link above. Who knows, perhaps Mojang will see this and decide to include arm native libs--wouldn't that be great?

Note that you will have to replace xxx and yyy in the commandline

      --username xxx \
--accessToken "yyy" \


xxx is your username that you used to register Minecraft. The yyy token is from the ~/.minecraft/launcher_profiles.json "clientToken". It is a long string that should have been setup when you did the first run of minecraft.

### Run Minecraft

Copy the commandline to ~/Minecraft/run.sh and chmod +x run.sh. Running that file should allow Minecraft to find the native files and run on your TK1.

Enjoy!