Par thy Android – A short followup on “60 FPS to 500”

Last week we published a blog post briefly outlining several steps of optimization of a Haskell game. In the article, the last two steps, which referred to parallelism and concurrency respectively, were inverted, making it sound like the Android version was using the parallel library. This was not the case: parallelism was the last change to be introduced chronologically, and we had never tried that on Android.

There was also a mistake in the code that printed the FPS for the renderer (hard coded number of frames, leading to an error when it was changed from ‘every 10 frames’ to ‘every 20 frames’). All the figures for the renderer in the last post should be x2 (it will be fixed in the other article later on, and this remark removed.)

It turns out that, with parallel enabled, there is a substantial performance boost, reaching about 60 FPS in average for the renderer and the same number for the physics (between 80% and 100% faster than without parallel), making the game run at the performance we need for now. The tests are all being executed on a Galaxy Tab 2 with the stock OS. The game is printing output stats to the logcat (using a custom FFI function).

For those who might be thinking, after reading last week’s post, that the performance was too low on Android, I hope this comes as good news: by using par, and with just a few lines of code (Page 21 of Parallel and Concurrent Programming in Haskell), the speed nearly duplicates. We will still carry out other improvements anyway but, taking into account that all the optimisations were quite simple and we did not design the game to run fast but to be easy to read and understand, we consider this a success.

Next steps

This does not mark the end, but the beginning. Maybe not all games are possible, but now some are. It’s a foot in the door, nothing more. There’s still a lot of hard work to do. But this gives us all the opportunity to get into a market mainly dominated by a handful of languages, a chance to prove that FP has something useful to contribute to every user.

There are plans to apply the same changes to the opensource Haskanoid game (which, although using SDL1.2 instead of SDL2, suffers from similar issues), in the form of a step-by-step tutorial, so that people find it easier to evaluate each claim and don’t need to take our word for it. This may also be a good opportunity to scrutinize the testing procedure and provide better, detailed benchmarks, which at the present time are slightly hard to produce because each game input, and thus run, is unique.

We are bringing Haskell to mobile platforms. We are currently preparing out first Android game written in Haskell, and that’s why we need all your help. Please, let others know about what we are doing via Twitter and Facebook, so that they can be ready to try the game when it comes out. To all those who subscribed, followed, liked, sent supporting emails and donated via flattr, a very sincere, wholeheartedly thank you.

2 Comments

  1. michael

    As a professional Android developer I appreciate your efforts to prove that Haskell is a viable language on this platform.

    I find your story very inspiring. I have developed one game for Android too and developing another right now, so I would love to expore Haskell possibilities on Android too. Alas I lack knowledge of Linux platform and Debian flavor of it, which is mandatory to build working cross-compiler via Neurocyte solution it seems.

    I have read in your previous posts that it was easy for you and you experienced no problems whatsoever with it.

    I would be very grateful to you if you would have found time to write somewhat more elaborate tutorial on how to get Haskell development for Android up and running starting from which version of Debian is known to be best suited for it etc.

    Thank you for your efforts and good luck with your game!

    1. Ivan Perez

      Hi Michael,

      Thank you for your good wishes :)

      You are right: using Linux seems mandatory at the moment. Setting up the environment the first time was a bit of a challenge. We did run into a few problems, and some things took days of trial and error. Some steps are still manual, far from what Android Developers are used to with Eclipse. Hopefully, that will be improved in the near future. But, even now, it’s not awefully complicated either. Quite recently, someone requested assistance setting up the development environment, and a couple of days later he was already up and running. Once the environment is set up, recompiling and testing new changes is quite quick (compile haskell with cabal -> copy files -> compile android with ndk and ant -> install on device).

      The idea of a tutorial sounds great. As a matter of fact, we’ve been thinking of putting together a series of tutorials on game programming (from zero to the complete game published on github a couple of months ago), and making it run on Android could definitely be a part of the series.

      Good luck with your game!

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