Table of Contents

Running Optcarrot

Running the Demo

Start by installing the TruffleRuby JVM Standalone.

You also need to install SDL2:

  • brew install sdl2 on macOS
  • sudo yum install SDL2-devel for RedHat-based Linux
  • sudo apt-get install libsdl2-dev for Debian-based Linux

Then clone the optcarrot repository:

git clone
cd optcarrot

Then you can play the Lan Master game.

On Linux:

ruby --jvm bin/optcarrot --print-fps --sdl2 --audio=none examples/Lan_Master.nes

On macOS, you need an extra flag, --vm.XstartOnFirstThread, for the GUI to appear:

ruby --jvm --vm.XstartOnFirstThread bin/optcarrot --print-fps --sdl2 --audio=none examples/Lan_Master.nes

Note: --audio=none is used since the audio is not nice at non-60FPS speeds.

To play, use keys 17 (not on numpad) to scale the screen, X for OK/turn right, S for turn left, arrows to move around, and Q to quit.

More information can be found in this blog post.

Here is a recording of a talk running the demo on TruffleRuby and MRI.

Running on Other Ruby implementations

You can also run it on MRI for comparison. You will need to install the FFI gem with:

gem install --user ffi
ruby bin/optcarrot --print-fps --sdl2 --audio=none examples/Lan_Master.nes

You can also run it on JRuby if desired:

jruby bin/optcarrot --print-fps --sdl2 --audio=none examples/Lan_Master.nes

Running as a Benchmark from the TruffleRuby Repository

If you have a local checkout of TruffleRuby, you can also use the version of OptCarrot under bench/optcarrot. See the Benchmarking documentation for details.