PVG Interview with Pocket Physics designer “0xtob”

There is an exciting and vibrant DS homeberw development scene, with more and more people interested in writing their own indie programs and games for the system. Over the past few years, a handful of coding pros have delivered some very impressive homebrew games and applications (also check out our interview with the maker of Phidias, a homebrew paint program). One of these talented DS programmers is 0xtob, a fellow DS lover from Germany that took it upon himself to code up some nifty DS apps including Pocket Physics, a neat little sandbox game that allows you to draw shapes and play with them using the rules of gravity. Think of it as a cross between Line Rider and the upcoming Crayon Physics Deluxe for the PC. 0xtob was nice enough to give us some insight about the current state of DS homebrew and his experience with it:

PVG: Your Pocket Physics DS application is a neat and impressive program. Is it tough to work with physics on the DS? How well can the system cope with physics?

0xtob: For simulating physics, I’m using the Box2D library. The author is spending a lot of time finding the most efficient algorithms for physics simulation and has really done fantastic work! Still, it’s a hard task for the DS, because the main CPU (66MHz ARM9) is rather weak and has no FPU (Floating Point Unit), which is why I had to change Box2D to use fixed point math instead.

PVG: What’s the most challenging aspect of developing DS homebrew applications?

0xtob: You mean besides finding the time for it? Well, the DS as an embedded system has a lot of limitations, like the rather slow CPU and limited amount of memory. One of the most challenging, but also fun, aspects of homebrew coding is that you are forced to write efficient code. You really have to think about how to get your algorithms to be fast and memory efficient.

PVG: From your experience, is there anything homebrew developers can’t do on the DS at this time?

0xtob: The homebrew and hacking communities have done an excellent job on the DS, and by now all the hardware has been completely figured out, so we can really use the DS to its full potential, and even beyond that: there is a homebrew FAT driver (libfat) that allows accessing the file system of the card you’re running homebrew from, so you can exchange files between your DS and your PC, which is something that you cannot do with commercial games. Also, there are homebrew hardware devices like the DSerial, which is a serial interface that can be used for connecting the DS to hardware like GPS receivers or MIDI keyboards, or the DSMotion, which adds Wiimote-like motion sensing to the DS.

PVG: What’s your advice for wanna-be DS programmers; where should they start?

0xtob: First get a homebrew adapter card, if you haven’t got one already. There’s a wealth of great homebrew applications and games, and even if you don’t code, such a card is well worth the money. I’d recommend a slot-1 card, because they are the easiest to use. You should have some experiene in C or C++. If you don’t, start writing C/C++ code on the PC fist; don’t learn DS coding and C/C++ at the same time! To get started with DS coding, follow a tutorial like Patater’s Introduction to DS programming or the Dev-Scene tutorials. But don’t read too much! Play around with the examples that come with DevkitPro; they show you how to use the hardware. Then just think of some easy project and start coding it. If you don’t know how to do something, look it up or ask. The DS homebrew community is very newbie-friendly. Join the forum or come to the IRC channel #dsdev on Blitzed.

PVG: Do you have plans for other DS homebrew projects in the future, or is there something you would like to do?

0xtob: Sure, I have a couple of ideas, mostly for music apps. I think it would be fun to make something like Electroplankton, but with more freedom and customization. Also, Wii homebrew is forthcoming, which is definitely going to be very exciting. But first of all, I want to finish Pocket Physics and make some progress on NitroTracker.

PVG: Any other DS homebrew games / applications that you would recommend?

0xtob: There’s too much great stuff to list here. Just browse the Dev-Scene Homebrew Catalog for a broad overview and visit the various homebrew news sites for the latest releases.

As you can see, the DS homebrew scene presents a great opportunity for wanna-be developers to get a taste for the hardware. Plus, the community is full of friendly and knowledgeable folks like 0xtob who can assist newcomers with their own projects. Sure, it takes time, effort, and lots of smartly-written code, but the end result is worth it. Thanks again to 0xtob for his work and for sharing his thoughts with us. If you are still curious about Pocket Physics, check out this demo of the program in motion: