Project Reality Forums

Just something that some people were unaware of, as they may not have used sniper rifles much as of yet, but was quickly made apparent due to many initial frustrating misses at long range for those of us whom have.

valued-tom asked: Is it true there is a trajectory decay on bullets, and is there a maximum range the bullets can travel from the sniper rifle?
[DICE]Sanosuke answers: Yes. Bullets do not just fly in a straight line in BF2.

Bullets do have simple behavioral physics on them in BF2, so this may lend itself to your coding.

I believe all that means is that bullets will drop as they travel longer distances. Even DICE/EA aren't dumb enough to make bullets just dissapear.

Indeed, that is what I am saying. Bullet physics.

I don't think the phrase "bullet physics" applies to the mysterious disappearance of bullets!

I know, I was reffering to the interview. The guy asked if there was a maximum distance a bullet could travel, wich means when it reaches that distance it would dissapear. Which leaves me confused.... what's the point of this post. I believe there has always been bullet drop, it's a part of physics and a part of BF. The one thing that isn't in BF2 is lead... wich makes no sense at all with these longer view distances.

Well it's either that or I'm a shitty sniper. Noooo, has to be the bullet physics!

So are the physics going to be changed for Project Reality? I'm not sure if every weapon has this implemented into yet?

There sure as hell is lead in Battlefield 2. I have been a sniper 95% of the time thus far since two hours after the demo was announced, for hours and hours each night.

There is lead, and depending on the circumstances, it can be significant.

As for there always having been bullet drop.. there was a lot of debate as to whether there would be or not. Hell, there were debates about whether or not PR would have to add bullet-drop if BF2 didn't come with any, way back when the site was still new.

That is the point of the thread.

well either way if you close up the scope seems wrong. being up close and being prone extra should yield a 100% hit at a 19 meter shot. also the target was standing still i was aiming for the upper body so if there was bullet drop it must also bullet sway also..

Well if there is bullet sway how are we meant to know how much it is? Thats kinda thing if affected by the wind as there is no little wind pointer showing its direction and strength!

Bullet physics is not particularly sophisticated in BF2, like most FPS games. Each bullet is not modelled as an entity within the game with intrinsic kinetics - it is more of a laser projection with built in adjustments for simple kinetics.

Compare this to WWIIONLINE, online flight sims like Aces High or boxed sims like Il-2 where each round becomes a physical object when fired. This allows for much more complex physics - it's a shame the BF2 devs didn't include a proper model in their game.

Well I know 1 thing for sure and that a bullet will not drop 1 meter downwards at a range of 10 meters or so even with strong wind. Itâ$™s not like you are shooting 750 meters which would let a bullet drop about 30cm or so but rather the hitboxes in this engine that are not that accurate.

Ugly Duck wrote:I know, I was reffering to the interview. The guy asked if there was a maximum distance a bullet could travel, wich means when it reaches that distance it would dissapear. Which leaves me confused.... what's the point of this post. I believe there has always been bullet drop, it's a part of physics and a part of BF. The one thing that isn't in BF2 is lead... wich makes no sense at all with these longer view distances.

There's no lead? So that's why I can't hit shit...

Interesting stuff..

I did notice that bullets in BF2 seem to have some sort of seemingly arbitrary degradation of accuracy over distance. However, to be trully realistic, you would have to model a 'parabolic' curve for each bullet. That is, each bullet in fact rises first as it leaves the muzzle of the gun until it hits a high point on the curve and then begins to drop.

To digress slightly, wouldn't this sort of per-bullet physics modelling be very CPU expensive? Especially considering a huge 64 player fire-fight, and god forbid, calculating environmental effects on the trajectory of a bullet..

What if a sort of 'fuzzy' modelling were used for guns with a high rate-of-fire? Say the first bullet is accurately modelled and if the users cross hair stays within a threshold of movement, then the rest of the bullet trajectory is not calculated, rather used from the initial calculation.

To use some horrible pseudo-code in an attempt to clarify my terrible English:
if (threshold > MAX_THRESHOLD) { Trajectory = calculateTrajectory()} else { Trajectory }

Would this work as a method to optimize trajectory calculations or is it useless garbage..?

Dowding wrote:Bullet physics is not particularly sophisticated in BF2, like most FPS games. Each bullet is not modelled as an entity within the game with intrinsic kinetics - it is more of a laser projection with built in adjustments for simple kinetics.

Compare this to WWIIONLINE, online flight sims like Aces High or boxed sims like Il-2 where each round becomes a physical object when fired. This allows for much more complex physics - it's a shame the BF2 devs didn't include a proper model in their game.

I only have a very elementary understanding of computer game programming, so please forgive my stupidity. It is my understanding that every bullet is an entity in all computer games that use bullets and collision detection.. I like the idea of each bullet entity having physical characteristics, like weight, velocity.. It hurts my mind to think about implementing the interaction of a game world with the bullet entity...

Very interesting stuff though..

Dowding wrote:Bullet physics is not particularly sophisticated in BF2, like most FPS games. Each bullet is not modelled as an entity within the game with intrinsic kinetics - it is more of a laser projection with built in adjustments for simple kinetics.

Compare this to WWIIONLINE, online flight sims like Aces High or boxed sims like Il-2 where each round becomes a physical object when fired. This allows for much more complex physics - it's a shame the BF2 devs didn't include a proper model in their game.

There is a reason World War 2 Online looks like **** - our PC's can't handle that many calculations at once. There are thousands upon thousands of ballistics calculations every second you are in any sized battle in WW2 Online, due to the fact that all of these are modeled as actual entities, rather than simple "laser" calculations. Material penetrations based on angles, velocities, weight, density.. for every single piece of shrapnel, every round of ammunition, explosive waves, you name it.

If that sort of entity-based physics was implemented into Battlefield 2, we'd have a nearly unplayable game.

I love WW2 Online, in any case.

phyte wrote:However, to be trully realistic, you would have to model a 'parabolic' curve for each bullet. That is, each bullet in fact rises first as it leaves the muzzle of the gun until it hits a high point on the curve and then begins to drop.

Actually the bullet won't rise after the muzzle, and if does that's only because you're aiming higher to compensate for the drop. I've been on a 150m range with a Finnish assault rifle (a variant of the AK47), and at that range you really don't notice the you're aiming higher. The sight adjustment is quite small.

In a months time I will be shooting the 7.62 RK 62 on a army reserve "rehersal". I'm also going to be shooting with the bigger guns i.e. a 152 H 88-40 Howizer. Think about the 152mm granade shell, when it explodes it creates around 4000 fragments with an effective range of 50-150 meters.

These bad boys do aim high I've shot with 76mm, 105mm, 122mm and 155mm also. The absolut worse to shoot is with the 105mm gun, the strong pressure field it creates almost hurts. You try to be as small as possible but it still gets to you. WHAM!

The bullet does rise as it leaves the gun, well not really, but it does, kinda.

The bullet will travel in a path that is always dropping toward the ground because of gravity. A straight "line of sight" can be drawn from the front sight to the target. The bullet will cross this line 2 times, once as it rises and again as it falls. It will only be rising because the gun is pointed slightly up, as Maasika mentioned, because of the alignment of the sights or the design of the gun.

Depending on the round and the distance to the target, your point of aim on the target will probably be different in different situations. If the round has enough power (or the target is close enough) to reach the target before it crosses below the line of sight, you will need to aim where you'd expect to hit it, or possibly below. This is because the bullet hasn't been effected by gravity enough to have fallen below the line of sight yet - the point where you aimed to hit.

If the bullet is still rising in it's arc (or at it's apex) when it reaches the target, there's a chance you will shoot over the target, or at least hit higher than you intended... your headshot now sent the bullet right over his head.

Move the target out farther, or use a less powerful round, and the bullet will now be falling below the line of sight by the time it reaches the target (thanks to gravity)... you will need to aim higher that you'd expect in order to compensate for this, so the bullet will "drop" onto the point you want to hit.

There certainly is a parabolic arc in the path of a bullet... and from reading the interview quote in the first post, it looks like BF2 takes this into account. The question is - how accurate is the ballistic data they are using in the game? Has the data been adjusted for the ranges typically fired in the game? It's nothing for a sniper to be shooting a target 300-500 meters away in real life, but that sort of distance is pretty far in this game. I imagine there has to be some "fudge factor" in the ballistics here, because a 1,500 meter sniper shot in this game isn't likely.

I'm curious... has anyone figured out excatly what the scale of these maps translates to in real life? Sorry if it's an obvious question, it's something I haven't seen yet and I'm really curious to know if it's possible to figure it out somehow.

Okay, but that's a mere technicality.

The round will not rise in relation to the muzzle. It will only drop.

i read somewhere that heat can cause a bullet to rise on its way to a target, cant remember where though so dont quote me on that.

I don't think heat would be enough to counteract gravity.

For example, if you dropped some molten copper, would it momentarily float?

Remember that if you drop an unfired round from barrel height at the exact moment that a round exited the muzzle of that rifle, the two rounds would hit the ground at the same time (assuming a flat plane with unlimited length). The only difference between the two is that one would travel really, really far in that time.

Heat wouldn't counteract gravity, it would allow the bullet to be more deformable while flying through the air, and allow itself to "teardrop", the effect by which it would start to deform into a shape which causes less air resistance, and allow it to fly farther.