One-man band: Glenn Corpes on how old skool tricks kept Ground Effect under 10MB

One-man band: Glenn Corpes on how old skool tricks kept Ground Effect under 10MB
When it comes to the canon of British game programmers, we'd be happy to second Glenn Corpes' application into the hall of fame.

From his early work at Bullfrog (Magic Carpet, Populous, Syndicate, Theme Park, Dungeon Keeper), he moved to EA following Bullfrog's purchase, and he's since worked as an independent at Lost Toys, as well as freelancing for Kuju and back at EA.

Now however the programmer is flexing his wings as a one-man band with his soon-to-be released Ground Effect flight racer.

We caught up with Glenn to find out what he thought about the iPhone as a piece of gaming hardware, his tricks for getting the most out of it, as well as his views on pricing.

Pocket Gamer: Why did you get interested in iPhone?

Glenn Corpes: It been over twenty years since I've been entirely responsible for a game. I've really enjoyed working in the biggest of game development teams but programming has changed.

As a graphics specialist, I had a lot of input into the look of the games I've worked on but it's been a long time since I'd had significant input into gameplay. This was mostly because others were employed to handle that stuff, but also partly because the ideas running around my head were for a different type of game.

But as I was losing interest in all but a few of the biggest new titles, casual gaming was becoming more and more important. The games that interested me the most were downloadable or browser-based. When Apple announced the App Store it seemed like it might be exactly the level playing field I'd been hoping for, and even though this game has taken me a year to release, the App Store still isn't dominated by big publishers.

I also have to confess that after a short period of arguing that "My Nokia does all of that and more", I fell in love with the iPhone and wanted to code it as soon as I started using one.

How does it compare to all the other platforms you've worked on over the years?

Programming for consoles always required several thousand pounds worth of hardware on a desk in an office for insurance reasons. Windows development always seemed to need a big, ugly PC with a noisy, fast, up-to-date graphic card.

It's great that for iPhone, the development hardware consists of nothing but my MacBook, an iPhone and the standard USB cable.

I also love the idea that I can program anywhere. Of course in reality I do 99 percent of development at a desk, with a big second monitor, a keyboard and mouse plugged into that MacBook, but for some reason the idea of being able to work anywhere still appeals.

As for the actual programming, it's halfway between Windows and console development. My Windows experience is proving very useful as there are already several different combinations of performance and features to worry about.

Embarrassingly, the hardest part of switching to Mac was several months of hitting the wrong keys while editing code. This was exacerbated by the fact that I also have a Windows version of the game. I had to adapt to switching back and forth. Luckily the Windows version is low spec enough to run on a virtual machine on my mac.

I should point out however that the Windows version of the has proved invaluable. It has the game's level editor built in, which means my kids have been able to design levels, and the other programmer who helped out was able to work on the game without even owning a Mac.

How did the idea for Ground Effect and Ekranoplan vehicles come about?

Many year ago, I worked on a racing game at Bullfrog called Hi-Octane. It was fun but a lot of us enjoyed it more before the power-ups and guns went in. Previously it had been a pure racing experience. Ever since then I've wanted to do a racing game focusing on the feel of controlling a vehicle skimming above an open landscape.

When I started the project, I tried to explain this to my non-gaming girlfriend but "You know, standard sci-fi hover car thingies" meant nothing to her. In an attempt to explain we spent some time on YouTube looking up Ekranoplans, WIGs and ground effect craft, with which I've been fascinated by (on an occasional basis) for a long time. It struck me that basing the game on semi-realistic vehicles went very well with what I wanted to achieve.

So, Ground Effect is a pure arcade racer in which your vehicle interacts with the level in a unique way thanks to the cushion of air beneath your craft.

Why do you think this type of game will work on iPhone?

The iPhone seems to be a platform where simple ideas flourish. Games that do a few things very well often seem to work better than those that try to squeeze a full blown console experience into the palm of your hand. Most people don't want to read instructions or commit to a serious block of time.

Ground Effect uses standard iPhone driving controls: accelerometer (or touch) steering, auto-acceleration, a brake pedal and a boost pedal.

Progressing through the game is all about learning the levels and mastering those controls. My primary goal has been to make piloting your Ekranoplan feel as rewarding as possible. I'm very pleased with how it's turned out and feel I've managed to create a unique mix of relaxation and tension.

What old skool tricks have you been using to push the 3D graphics?

The standard iPhone and iPod touch have impressive 3D hardware for a phone but the driver isn't very advanced. On pure polygon pushing it's roughly equivalent to where PCs were around ten years ago.

The speed of the CPU and the amount of the memory are rather more impressive. This means that the best approach is not to have as simple-as-possible graphic engine drawing pre-optimised objects. There are all sorts of opportunities for sneaky level of detail systems where the CPU has a bit of a think about what it asks the hardware to draw. This is also very efficient in terms of generating geometry on-the-fly with the CPU.

These are all techniques that haven't been used for a few years on consoles and PCs.

The graphics hardware also has the ability to apply two textures to a triangle at once. This fixed function multi texture was common on PCs for a few years but then it was quickly replaced by pixel shaders. As far as I can tell it's not used much on iPhone games but is a huge performance win. Luckily I happened to have the relevant experience.

There are also tricks such as fractal generation and load time calculation of lighting which mean that despite lots of huge, detailed levels, Ground Effect is under 10MB, meaning it can be downloaded over 3G.

What will you be doing in terms of social networking?

I always wanted Ground Effect to take things beyond online scoreboards by allowing players to download each other's best time replays and race against them. At least one of the social networking APIs seems like it might support this. I will be looking to adding social networking support when I'm sure I can do this.

As an indie developer, what are your views on App Store pricing, and do you know how much Ground Effect will cost?

I think it's a shame so many developers sink to 99c/59p. It's also slightly depressing so many iPhone/iPod touch users refuse to buy anything for over the minimum price. Ground Effect will be less than $5/£3 but I'm still deciding exactly how much.

Thanks to Glenn for his time.

You can follow process with respect to Ground Effect via his development blog.
Contributing Editor

A Pocket Gamer co-founder, Jon is Contributing Editor at PG.biz which means he acts like a slightly confused uncle who's forgotten where he's left his glasses. As well as letters and cameras, he likes imaginary numbers and legumes.


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