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Quake 3 Physics



So I played a lot of Quake 3 over the weekend, which is a fast-paced multiplayer shoot 'em up from id software. I hadn't played it in a long time, and I found an interesting phenomenon in the game physics that, while I had always used and known existed, I had never examined scientifically.

The term is bunnyhopping, which refers to the act of jumping everywhere you go in the game. The idea, in the game, works as follows:

1.) The player designating movement in a certain direction increases velocity in that direction.

2.) This is constrained, on the ground, by friction.

3.) While in the air, friction is negligible.

4.) Therefore, designating movement in a direction while in the air gains velocity unrestrained by friction.

5.) Minimizing contact with the ground by jumping at the precise moment of impact with the ground allows a net gain in velocity every time.

As speed makes one harder to hit, there is an obvious tactical advantage here, which is why most Quake games degenerate into characters moving so fast as to be unrecognizable. Quake pros, of course, can hit anybody at a hundred yards while moving the speed of an F-16. (I am not a Quake pro)

What is interesting about this is I am told by my friends on the cross country team that to maintain velocity in real life differs from inclined planes to flat ones. On flat ones, one should maximize the number of small, quick steps one takes to gain velocity, while when going up or down hills, one should (as one might in Quake) take long bounding strides to avoid contact with the ground to preserve velocity.

The difference of course, lies in the fact that the Quake designates movement for the player is arbitrary at heart. In real life, one needs friction to apply a force from the foot to the ground, angling it so that forward movement can be attained, whereas in the Quake engine, a forward velocity is simply given.


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I really like the application of physics to video games. That's a pretty cool idea, especially considering a good amount of video games neglect physics. Come to think of it, the physics of Super Mario sounds like an interesting investigation...I might have to look into that.

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I learned something new today -- great analysis of running, and given how much I run as part of our crossfit workouts, I'm looking forward to giving the stride variation a try!

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