http://www.racesimcentral.net/
about physics model:
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Greenawalt: Forza Motorsport is a pure simulation engine wrapped in an
accessible motorsport-based game world. With realistic assists, fantastic
tactile control, and player feedback, gamers will be able to pick up and
play. However, because of the depth of the physics, the player can continue
to learn about the car and travel the path of mastery as a racing car
driver. Every car is a new experience. Weight and friction transition
realistically, allowing great racers to express themselves through their
driving. Meanwhile, we've employed realistic traction and anti-spin assists
that will allow inexperienced drivers to compete and be successful.
Our tire and suspension model is extremely realistic. We partnered with Toyo
tires to get real-world data on production and race tires to model in the
game. Our tire model exhibits pressure, wear, heat, and load sensitivity.
Tire friction is also affected by the *** groove and marbles on the road.
We worked with an engineer from Ferrari's F1 program to completely simulate
real-world suspensions. When configured to simulate a double "A" arm
suspension, the track decreases as the suspension compresses and negative
camber is introduced. In turn, the camber and weight affect the tire heat
and thus pressure. Most consoles simply do not have the power to compute
what we're computing for the physics and still render a game.
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influences:
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Xbox.com: Were there any racing games that inspired your team? If so, what
were they?
Greenawalt: Obviously, the GT series has been a huge influence on this team.
Personally speaking, the original Gran Turismo was the only reason I bought
my first console. Without that game, several of us probably wouldn't have
become involved in this industry. Polyphony has created a great series.
I'm sure many will see the influence of SEGA's classic Ferrari 355 coin-op
game in our E3 presentation. We have a 355 machine with a triple-screen set
up in the lobby of our office. The art lead and I still love to play the old
Sportcar GT game for the PC. It was a great blend of simulation and
accessible fun. It also had really cool cars and real-world tracks.
A few team members participate in PC online racing sim leagues for Papyrus'
Grand Prix Legends and NASCAR Racing 2003. These games have a small, but
fanatical following. Some of these communities have created third-party
telemetry and replay analyzer programs as well as huge content mod packs.
Recently, one of my buddies showed me an online league based on a version of
F1 2004 that was mod-ed to have FIA GT and ALMS cars and tracks. That looked
pretty fun . but extremely challenging. These hard-core communities are a
better source of inspiration than any game could be.
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about AI:
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Xbox.com: Realistic artificial intelligence seems difficult to achieve in
games. How is the development team ensuring the quality of the single-player
experience?
Greenawalt: Everyone talks about A.I. in racing games. Rather than spitting
out features, let me simply frame our approach and let you draw your own
conclusions. You know when I was saying that we've assembled a team of
all-stars? I wasn't kidding. We actually have several high-level developers
working on our A.I. alone. Our main A.I. developer is new to games, but
incredibly experienced in A.I. He's a PhD A.I. developer from Microsoft's
research division. In the past, he's worked on robots and learning A.I.
systems. He's teaming with our research division in Cambridge, England, to
approach A.I. from a completely different angle.
It's really cool to see a group approaching this problem from a completely
new angle. Rather than giving the A.I. different car physics, a predestined
spline, and random seed to mix it up, these guys are creating thinking A.I.
that drive Forza Motorsport's remarkably complex physics engine. Even our
A.I. difficulty levels are based on learning artificial intelligence.
Lower-difficulty A.I. makes human-like mistakes, such as late braking and
late apex-ing.
It's sort of hypnotic to watch the A.I. learn. I'll tune a new car and give
it over to the developer to train the A.I. driver. The A.I. driver then
takes over the car and starts putting together laps. The laps get better and
better as the A.I. tests out the new car's limits. After a couple of laps,
the A.I. is putting together really fast times in the exact same car physics
the player drives. What's even more amazing is that the A.I. doesn't have to
relearn on other tracks. It just applies what it knows about the car's
abilities and starts churning out hot-laps on the new track.
If you don't work in this industry, you might not understand how
unprecedented this is. Every other racing game I've seen has used slightly
different physics and predestined splines for the A.I. The artificial
intelligence in Forza Motorsport is truly intelligent.
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damage:
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Xbox.com: How will physics and damage modeling affect gameplay?
Greenawalt: The on-track experience is a simulation. However, we have
customizable levels of difficulty, in the form of damage, assists, and
opponent skill, that allow you to alter your experience.
Forza Motorsport features performance-affecting damage. However, realistic
damage can be extremely punishing. Therefore, we've integrated damage into
the difficulty system. You can play with fully simulated damage, limited
damage, or simply cosmetic damage.
Challenging yourself will increase the rewards for winning. With the
difficulty settings at default, I expect most players to be able to pick up
and play the game successfully. Meanwhile, they are encouraged and armed to
grow their racing skills.
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customization:
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Xbox.com: To what extent will players be able to customize their vehicles?
Greenawalt: The upgrades fall into three buckets: appearance upgrades,
performance upgrades, and performance tuning.
The cars, from more than 60 manufacturers, include some hot sport compact
cars like the Dodge SRT4 and Nissan 350Z. We've licensed real-world body
kits for the hot tuner cars. These are the appearance upgrades. Based on the
number of kits we've created, we have several billion possible visual car
permutations. Of course, we are a simulator, so each of these kits has
weight and aero components to them as well. We also have an extremely
powerful paint job editor. This editor allows you to place decals and vinyl
primitives all over the car. You're not limited to specific shapes and
locations, so you can go ahead and freestyle.
As for tuning and performance upgrades, let's just say, you've never been
able to do the level of tuning available in Forza Motorsport-ignition
timing, boost pressure, fuel ratio, not to mention the standard tire
pressure, camber, caster, toe, gear ratios . In the upgrade category, Forza
Motorsport includes everything you need to transform your stock performance
car into an absolute track monster. And, of course, all of the parts are
based directly on real-world upgrades you'd find on the track, from
cat-bypass and cat-back exhaust to centrifugal superchargers, large surface
area intercoolers, cold air intake, and triple-plate
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