Posted: 01-06-05 In: Interviews By: Munro2 |


Havok physics is at the heart of the eagerly awaited Half Life 2 from Valve Software. Physics gameplay is considered one of the key new departures in the sequel and is an integral part of the game experience.

Halflife2.net: How was your relationship with Valve during the development of Half-Life 2? Do you plan on working with them in the future?

Havok: Valve were one of the earliest users of our technology, and were able to give us great feedback throughout their development of Half-Life2. They really understood what it could do, and its limitations. With Valve’s input, for example, we completely re-implemented our constraints system. We certainly hope to continue working with Valve.

Halflife2.net: How long did it take to develop the Havok 2 Engine?

Havok: The Havok 2 engine is simply the latest iteration of our physics engine. Development started on our physics as early as 1999, and we have been refining / rewriting parts of it ever since based on the feedback from our customers. Our product development team has had approximately 10 engineers working on the core physics for the last 4 years.

Halflife2.net: Was Havok 2 developed primarily for games? Or did you have other purposes in mind?

Havok: Havok 2 was developed as a games solution from the start. The design decisions we took during its development were all based on this assumption. For example, wherever we can get away with it we will happily sacrifice accuracy for speed. Havok is used outside of games though – for example the team responsible for the Burly Brawl scene in Matrix Reloaded used Havok to pre-visualize and simulate the motion of the Agent Smiths.

Halflife2.net: Did you have to change/add anything in the engine specifically for Valve?

Havok: Sure. We listen carefully to what our customers tell us because ultimately it’s about the game and how fun / cool it is. For Valve, for example, we did extra work on constraints (improved the ragdoll simulation).

Halflife2.net: Is there any truth to the rumours of legal issues between yourself and Valve?

Havok: I don’t know what the rumours are, but our relationship with Valve has always been a good one.

Halflife2.net: What makes the Havok engine itself unique (other than the games that use it)?

Havok: Well, the games that use it are the key to why the engine is unique. Every time we’re used in a game by one of our clients the engine improves further based on the feedback from the client. We’re now in over 100 games – that’s a lot of games experience that’s built into the engine. Sure, we could talk about features and performance and all that but ultimately the most important thing is: does Havok understand what it takes to make game physics work? We’re still learning but we’ve more experience of this than any other provider out there.

Halflife2.net: How many full time engineers work for Havok? What is the breakdown in terms of education, e.g., how many have Bachelors degrees, how many have advanced degrees? What would you look for in a programmer if they applied for a job?

Havok: There are currently 26 full time engineers working for Havok all with Bachelor Degrees, mostly in computer science, computer engineering, or mathematics. We have PhDs and Masters degrees too (but none of these were in physics). You don’t need to have a higher degree in physics to work on a physics engine. We look for people with a love of programming, who get stuff done, and get as excited as we get about what we do.

Halflife2.net: Did the release of the stolen files from Valve have any effect on Havok (the company and/or the engine)

Havok: Like everyone else, we double and triple checked all our own security measures – that’s about it.

Halflife2.net: What are your plans to advance your character animation technology in the future? Do you plan to move beyond ragdoll physics and support full physics based character simulation?

Havok: I think ragdoll physics are starting to become quite commonplace, especially in first person shooters. With our help, our clients are starting to go beyond the common ragdoll effects you see in games today. We’re looking at more realistic ragdoll modelling, and also how to expose the power of the ragdoll simulation to the character animators to give them much more control over the dynamics.

Halflife2.net: Have your engineers been working on real-time fluid dynamics for smoke/gaseous effects, and/or water? If so, how can these effects can enhance gameplay for both casual and hardcore gamers? If not, are fluids on the agenda for future versions? Is there any chance we'll see them in the near future?

Havok: We have looked at these in the past, but nobody we have worked with has really come up with a good way to incorporate these into gameplay, with the possible exception of the use of a simple buoyancy effect.
We are only just coming into a time where physics is being used generally by games to enhance gameplay. I think in the near future we will see this become more prevalent, as game designers start to explore the possibilities physics presents more.

Halflife2.net: Does the Havok engine have any sort of support for sound simulation, i.e supporting sound dynamics and interaction, superposition, etc. of sound waves with other objects? And if not, how easily it would be to implement into the Havok engine?

Havok: We don’t simulate anywhere near the frequency needed to synthesise sound, so we don’t do wave superposition etc. For details of what you can achieve, you should see Brian Sharpe’s (from Ion Storm) talk at GDC this year. They have been using the Havok engine as the basis for physically based sound effects.

Halflife2.net: How many lines of code is the engine?

Havok: That depends – on what platform? Do you count assembly / microcode? Do you count the tools used to create content, or the debuggers…? Lines of code are somewhat meaningless as a metric – remember that on consoles in particular we try to keep the engine as small as possible because of the limited memory of those systems. We’re an embedded software component, so we have to be fast, tight, efficient and robust.

Halflife2.net: Do you plan on supporting the Independent Game Developers in some way? Offering the Havok 1 engine for a low price or by designing a separate engine for Indy developers possibly?

Havok: Hey, we’d love to. We’re all indy developers at heart!! But, all our resources are focussed on delivering good software and fantastic support to our clients to help them deliver games. So right now we’ve no plans this.

Halflife2.net: To what extent can mod developers change or modify the Havok settings/engine?

Havok: This is up to Valve, They choose what level of functionality to expose. The physics will of course be customizable and tweakable but Valve have worked hard to make sure it is as easy as possible to harness the creative potential of the physics. We’re incredibly excited to see what the mod guys are going to create with the Half Life 2 engine.

Thank you to those at Havok for spending the time to answer these questions.