Ballistics in OFP?

[Risasi 0]

Okay. I'm sure this information can be found elsewhere, but for the life of me I cannot find it. I've searched for over an hour now.

What about physics for ballistics modeling? Do we have to account for windage and elevation? i.e. When one shoots his rifle does the bullet travel in an arc rather than a laser like straight line?

I think it does for OFP:E, but I just assumed it does the same in OFP for PC. An answer would be appreciated.

Regards

[SeppSchrot 0]

Gravity is taken into account as is the time for the flight so you have to aim higher for distance shots and the impact does not occur immediatly. Of course, the primary factor is the velocity of the projectile.

With a fast vehicle and slow traveling visible projectile, you can even chase it or even catch it up.

(The engine might differ between small rifle rounds and the big ones from tank guns/launchers. But affected by gravity are both kinds.)

Based on my observation, wind is not taken into account. I'am not aware of any loss of speed due to air friction either.

There are two mods, FFUR and WGL. Both of them add very visible tracers to most ammo. You can observer the flightpath better with these.

[six6six 0]

Wind is taken into account, its just most of the time, only snipers will be firing far enough and tank shells are to heavy to be affected that much.

[Pulverizer 1]

Wrong. Wind does not affect projectiles in OFP nor ArmA. Not without user-made scripts.

Even when you see lateral shift it's not caused by wind but probably due to the game seeing that the gun is not upright or some bug related to sloped terrain. You can tell because it does affect some particle effects and the parachutes. Why would wind to any direction always push the rounds to the east when you fire from a certain position for example? Why doesn't it ever affect rounds fired on flat ground such as an airfield even though it affects smoke nades on the very same place and time?

---

Air friction does slow the rounds in OFP. You can prove this easily by shooting below the horizon from high ground and monitoring the velocity. If there was no air friction the round would actually accelerate but it does slow down:

Event handler to catch a bullet:

this addEventHandler ["Fired", {nearestObject [(_this select 0),(_this select 4)] exec "fired.sqs"}]

;fired.sqs to output velocity =

#l

_v=velocity _this

_x=_v select 0; _y=_v select 1; _z=_v select 2

_v=sqrt(_x*_x+_y*_y+_z*_z)

player sidechat format["v = %1",_v]

?_v>0: goto "l"

[sanctuary 19]

Additionally to that, in OFP there is a small dispersion from any weapon you can fire with, but it has nothing to do with winds, it is due to the dispersion value that is defined for each weapons in the config (by example the BIS M16 has dispersion=0.0002; in single shot and dispersion=0.0004; in burst).

By changing those values you could obtain high dispersion weapons like with JAM , so you could have longer firefights to compensate with the OFP "flat" grounds that feature no natural obstacle and hard cover.

(The AI could be affected by its own dispersion with the aiDispersionCoefX and aiDispersionCoefY values)

[Risasi 0]

Wow, thanks for the info. I wasn't expecting so many quick answers.

Okay, so its not using true flight physics. Too bad, that would have been mucho sweet. I'd go build my own virtual island just to get some long range target practice in. Ammunition is getting pretty expensive nowadays.

Quote[/b] ] (by example the BIS M16 has dispersion=0.0002; in single shot and dispersion=0.0004; in burst).

When you say dispersion I assume you are speaking of the inherent inaccuracies found in projectile weapons? I assume that .0002 is at some arbitrary distance? Like say 1, 10, or 100 yards? Wow, if so I wish my AR's were that accurate...

[sanctuary 19]

Quote[/b] ]When you say dispersion I assume you are speaking of the inherent inaccuracies found in projectile weapons? I assume that .0002 is at some arbitrary distance? Like say 1, 10, or 100 yards? Wow, if so I wish my AR's were that accurate...

The dispersion value actually means that your bullet will not go exactly in the direction you are firing.

The default values for the BIS m16 are so smal that you do not really see the effect and so you "think" that the bullet actually go where you are aiming, but try some higher values and you will see the real effect of the dispersion value.

In other games this effect is called "cone of fire" as it is way more noticable (their dispersion value being way higher thatn in vanilla OFP).

[Risasi 0]

Yep, that's what I thought you meant Sanctuary.

Your "cone of fire" is quite common in real firearms. Depending upon such variables as rifle design, bullet design, consistency in bullet load, and a whole bunch of other boring stuff.

And if your .0002 is as tight as I think it is, the weapons in OFP are crazy insane accurate. But what the hey, it is just a game after all.

Thanks for all the info though, helps me set my expectations.

Risasi out (who is still waiting for his copy to arrive from Amazon)

[Pulverizer 1]

Ah, of course there's dispersion, forgot to mention it since there's hardly any by default. You don't want to play with the original stuff anyways except for nostalgia's sake so it's not a problem

I think it should only be called dispersion in OFP. Cone of fire or expanding ring is usually used to describe the non-existant ballistics in shooters like CS or Rainbow Six where you shoot "laser" bullets through your lens (you are actually a floating camera with underslung hands in these games).

In OFP, the bullet actually originates from the barrel of the gun model and it has a velocity which is changed during flight by air friction and gravity. When you run so that the gun is pointing to your left, that's where the bullets will go. Where as in most other semi-realistic games, you move and the laser deviates to some random direction centered around the crosshair.

[Risasi 0]

FYI; I was play testing WGL 5.12 on Everon w/ WGL re-texturing.

I was taking pot shots at a squad of men in some buildings. A few of them had hit the dirt when I started shooting. I noticed my bullet was kicking up dirt in front and to the left of them. So I had to count for elevation, AND adjust for windage.

So I was a little stoked when I saw that. Thanks WGL.