ATTN Nexrun, Warsow: speedhack/cheat possible!

[divVerent]

http://www.youtube.com/watch?v=xNRca0gSZQ0
http://rm.endoftheinternet.org/~nexuiz/yourecheater.avi

A speedhack, not exploiting a protocol flaw, but a very well-known flaw in Quakeworld-style movement physics (affecting Quakeworld, Quake 3, Quake Live, Warsow, CPMA, Defrag, and Nexrun).

It is the very same flaw you know as "bunnyhopping", except used in a mathematically perfect way, and bunnyhopping direction alternated every frame to get forward motion.

Regular Nexuiz player physics are not affected due to "sideways friction", that is, reducing the sideways component of the velocity to reduce the impact of Quakeworld bunnyhopping (which only is effective at speeds from 400 to less than 700 units per second due to this).

I won't port this cheat to any of the other mentioned engines, but it's quite simple and straightforward to do, so yes, Warsow developers should be aware of this too, and possibly devise countermeasures now (before people actually implement it for their engine).

[TVR]

Strafe-running/Strafe-jumping is an exploit that those modifications deliberately include.

Then again, Warsow is intended to allow every single exploit possible with ioquake3, graphical detail is low to entail use of the 333 fps exploit.

[divVerent]

A countermeasure against strafebot is in place in Nexuiz svn now.

Strafebot can of course be changed to work even with that countermeasure. However, it then looks like THIS:

http://www.youtube.com/watch?v=6jkGzeiiUiA

I think it's hard NOT to notice someone using it. When watching a demo, when spectating him, when watching him on the map, it's obvious in any case.

[Lee_Stricklin]

A countermeasure against strafebot is in place in Nexuiz svn now.

Strafebot can of course be changed to work even with that countermeasure. However, it then looks like THIS:

http://www.youtube.com/watch?v=6jkGzeiiUiA

I think it's hard NOT to notice someone using it. When watching a demo, when spectating him, when watching him on the map, it's obvious in any case.

LMAO Epic cheat FAIL

[Darcshadow7]

Lol owned.

[C.Brutail]

Interesting. Btw. how do you find these?

[divVerent]

I got the idea by mathematically analyzing strafe-wallhugging (supposedly a bug, but after my calculations, a direct consequence of QW style bunnyhopping physics).

BTW, improved my cheat client even more now. I got the following "useful for anyone" info by working on this cheat client:

- QW bunnyhopping is effective in Nexuiz in a speed range of 400 to 899 qu/sec. At higher speed, just holding forward is better. However, gaining any speed by bunnyhopping above 700qu/sec is something even FruitieX cannot do (but my cheat client can).
- test99 can be beat using the cheat client quite easily (the jump over the slime is REALLY simple with the cheat, and dodging the turrets is too).
- Even the new version of the cheat client is VERY detectable in demos. It also has a mode to just do circlestrafing but not alternate directions like wild, as you see on the youtube video - but its aimbot-like direction snapping that's synced to the showpressedkeys for the strafe keys would give it away quite easily too.

Due to the countermeasures now implemented, any use of a strafebot-like cheat can be easily detected by watching a demo from the cheater's point of view. Thus, strafebot is no danger to Nexuiz.

However, even though it is no danger to Nexuiz, I won't release the cheat client. The knowledge gained by writing this client will however be shared with anyone, just like this fact that bunnyhopping is effective in regular Nexuiz physics for speeds up to 850qu/sec, and that test99 is far from impossible

Interesting mathematical results:

1. Accelerating in some direction makes you slower because of sideways friction if:
sidewaysspeed^2 * (sidefric / maxspeed) < accel * forwardspeed
2. bunnyhopping can only be effective if:
speed >= maxspeed && speed * (1 - accelqw) <= maxspeed
(in Nexuiz: speed is >= 400 and <= 2000)
3. (1) and (2) together yield (speed * speed - maxspeed * maxspeed) * sidefric < accel * maxspeed * maxspeed, or speed <= maxspeed * sqrt(accel / sidefric + 1)
(in Nexuiz: speed is <= 899)
4. ideal bunnyhopping is bunnyhopping so that you JUST get full QW-style air acceleration.
5. higher cl_netfps allow slightly higher speeds when QW-bunnyhopping