Nickname: I have two. My original nick on IRC and when I was playing in Q1 clans was Gaffer but I am known as Experimental in Tribes.

Irrational Title: Senior Programmer

Qualifications: I've started and not finished about three degrees, basically Mathematics and Computing. I've got a pretty good background but I still want to finish it. I recently did some really nice Mathematics study at ANU when we were prototyping Tribes, which has come in quite handy. Other than that I have no real formal qualifications. I worked at Auran just after Dark Reign in 98, 99, that was pretty cool, Mostly did 3D engine programming. Then I kind of choofed down to Sydney ran my own business and did contract programming during the .com bubble in North Sydney for a brief while and then I flew down here around about the start of 2001.

Previous Games: Freedom Force. I did the physics and movement for that, plus the sound programming. Before working at Irratonal I did some work on the Sage engine, which has become the Jet Engine over at Auran. I joined just after they shipped Dark Reign and if I stuck around I could have made a train game. So that's why I left *laughs* Look, I'm sure they are going financially great it's just that I didn't find it all that exciting.

Batman?

Hardest moment in development of any game you have worked on: Probably when Sierra came down and we had to crunch. They came down and gave us a sort of a visit last milestone, and we were right in the middle of resolving a lot of issues with Classic T1 versus Tribes2. There were a whole lot of issues like how much we wanted it to be like T1. A lot of conflict going on about it and resolving that, getting through it and putting in some new things. Getting through that was probably the toughest moment. That's about the same time I changed nicks from gaffer to experimental after the new "experimental" physics I was working on.

What where the Sierra heads like:
They were great actually, they were really cool. I kind of spent time with Chris and Rich, all the guys were great.

First gaming System: My first PC gaming system was a 286 AT around about 1989. I also played a lot of what my mates played on the Amiga, Atari ST and C64. My earliest gaming experience was an Atari 2600 around '84.

Favorite Game of all time: That's almost impossible, um Zelda Wind Waker and Metroid Prime. More oldschool stuff would be UFO Enemy unknown, the original Prince of Persia and out of this world / another world.

What are you currently playing: Nothing at the moment. I want to get Viewtiful Joe, its this weird crazy Japanese platformer. I want to play Prince of Persia and Viewtiful Joe pretty much, maybe the new F-Zero. The most recent game I got was Soul Caliber and it's exactly like the first one, you got to have friends to play it with, so I don't play it that much.

Gaming at home: An old Dual P3 500. Gamecube for gaming and I do the internet thing on the PC. I want to get a Mac, cant stand PC's I want to go home to a G4 Mac laptop, one of those PowerBooks. Actually I don't care as long as it's not a PC *laughs* Mac OS 10 is fantastic. I should show you my desktop, I've jiggered it up so that it looks just like Mac OS 10, just with object dock, it's really cool. You got to kind of tune it and stuff but its fantastic, I only really run 10 programs and out of that only 3 or 4 regularly so it's just perfect. Hide the taskbar, and all your icons. Just get rid of them and then you've got a Mac, almost, pretty sad really. *laughs*

Single player or multi-player or co-op: On PC's generally multiplayer, I haven't done much lately, I played return to Return to Wolfenstein when it first came out and that was interesting. I never got into the Counterstrike "whack a mole" sort of genre, I was pretty seriously into Quake. I was one of the early Q1 shareware guys. We where clanning and having matches and going "Oh the full game ruined it all the maps are too big and you know going on about all that" that's was about 95,96 I was pretty seriously into that. I started hearing Quake noises when I went out at night and stuff like that, pretty messed up. I played Diablo after that and finished single player and started doing the MP and it pretty laggy and bad overall. But aside from that I just kind of went, I'm not going to let myself get addicted to this again. You see the Multiplayer addiction and you go, I want to do something else. Since then I haven't really done any serious PC gaming, mostly consoles. You can pick up a console game, it grabs you for 2 or 3 weeks and then you're done. Which is kinda sad because I wish I could keep playing games like Wind Waker because it's a fantastic game. There are cool games like Monkey ball, it's a cool physics based game but it really starts annoying you after about a week of playing it, There's no replay there, really.

Could you please give us a brief run down on what a physics engine is and what Havok and Karma are?
There are actually 3 engines. There is the standard Unreal, which is how guys move around in Unreal and that's like 1995. We recently found a bug in it where it applied half the gravity per frame instead of full gravity, so they compensate by instead of 9.8mr/s its like 18. In Unreal, I am not kidding you, it's very funny. We use that as little as possible because we dont like it very much. Its really only used when you drop ammo or when you shoot guns. I wrote a system called Fusion completely from scratch to replace the unreal movement physics. Fusion replaces character movement and nothing else, that's all its for.
Havok is about objects rotating and spinning around and joints and vehicles and all those kinds of things, it can do the stuff we need to do but it has um. Sort of like if I fire a bullet and its going fast enough and the games ticking over at 100fps, in one instance it will be on one side of the wall and the other instance will be on the other side of the wall, and it won't ever have actually discretely touched the wall, that's called tunneling. Havok is more about low energy; low speed and we had to set up our system in a custom way so that we could stop tunneling. Effectively that means that the player is 2 spheres. You kind of sweep their volume along from their start to end position on the frame. So instead of just checking point A and point B, we sweep the whole thing from point A to Point B and you search for anything in-between.

So fusion is your home brew system?
Totally, it is completely written from scratch. It is so custom not only did we rewrite the entire movement system with jetting etc .we completely rewrote collision detection as well, because the collision detection was absolutely terrible. Stuff like sticking and jittering could occur in the prototype and we couldnt get skiing feeling exactly the way that we wanted it.

That is one of the things that happens in Tribes 2, the ski bug.
We actually had that in the prototype, and it was very frequent. in fact I am sure that it was much more frequent than the ski bug in T2. It was so bad and there was just no way to fix it,that it was probably the deciding point in us writing a new system. I've only just finished it and it's been very difficult to kind of stretch out the deadline, which you can do because it's so critical to the game. The amount of refinement changes and works with the designers was huge. It's not just like, you hold down jet and you get a constant force up, there's a lot of crazy stuff going on there. We didn't actually have anything that we could copy that from, we never wanted to copy from T1 although we sort of looked at the feel of T1. Mike [Michael Johnston] obviously knows that pretty well, but it was always a fresh implementation under the hood.

Can you break it down, what is Fusion, what is havok and what is unreal?
So to break it down, if you're in a vehicle or Ragdoll its Havok. If you're a character moving around its fusion and its only Fusion, and if you're firing projectiles it's Unreal. We try to use the unreal stuff as little as possible.

What is the Havok ragroll like compared to Karma?
The Havok ragdoll is great. You just put it in and it works. Sierra paid a fortune getting it in and it's just fantastic we've got actual support for it. Guys at Havok are setting it up for us. It just sort of slotted in and worked perfectly. We love it.

Thanks for your time Glen.