Firing Cone

[Tenshi]

I remember reading about the issues people had with firing and all of the explanations of accuracy based on accounts of the way the game works...one made mention to the fact that bullets dont leave the gun in a cone but in a cylinder. I couldnt find the thread so i started a new one.

Thought it might be useful to someone to know that that isnt exactly true. At the time i thought "that cant be right". I realised that in fact the bullets are projected in parallel through perspective distorted space. Which means that they do go through the world in a cylindrical pattern...but the space they travel through has already been perspective distorted. So the result is that the bullets DO cone out reletive to the environment.

This might be obvious to some but it might be useful to someone.

[NoseKi||s]

Re: Firing Cone

Wow.. it took me a while to get your point but i think you're on to something there :)

I read the post about the cylider shaped bullet spread too and i was baffled because it didn't sem to fit into what i saw in the game (when u use a mounted MG, the bullets trails do seem to spread out in a cone rather than in a cylinder shape).

So to put it in other words (don't know how accurate this is with my bad enlish): the "lateral" distance between two bullets leaving your barrel doesn't grow as the bullets fly on their trajectory. It only seems so because the world around the bullets gets "narrower" as they fly into the distance.

On the other hand, that would require that the perspective distortion would not apply to the bullets :S
So maybe the light trails we see have little to do with where the bullets actually fly.

Anyway.. Ppl have been complaining about this feature in BF2. Some ppl would like it to be point-and-click with no deviations, no firing cones, with linear bullet trajectories and no bullet travel time... In my opinnion, what we have now is much more entertaining.. The best point-and-clickers still have the best chance of getting the most kills but the randomness in accuracy gives some chance to those non-leet players too.

There's no easy way of simulating the process of lining up your front and rear sights in computer games, and if there was, i think it would propably just make the game frustrating.

[dadog]

Re: Firing Cone

very so, when i play as US and defend the sub flag in i fire the hj10 at the tank car etc and they kill me after i fire the round and it does not go out at all! or sometimes 10 seconeds later

[evilzucchini]

Re: Firing Cone

I have read what you have written about 5 times and really am not sure what you are talking about.

However, if the bullets fire out in a cylinder and not a cone, it would be just as easy to hit someone far away as it is up close. Deviation would mean nothing when relative to distance. . .which would be a stupid way to make the game.

However, considering I find it much more difficult to hit people at distance, even when they are standing still and I am using a sniper rifle, I would have to argue that it MUST be a cone shaped deviation.

[NoseKi||s]

Re: Firing Cone

This is a crappy illustration of what the different daviations would mean in terms of hitting the target.


U see that with a cone you have the same chance of hitting a far away target whether you actually aim on it or miss a little (given that the bullets spread equally in the cone). With a cylinder, aiming carefully makes more difference.

The drawback of the cylinder shape is that your chances of hitting don't grow when the target is brought closer (but it is easier to aim better as the target gets bigger). This also explains the times u thought u shot a full clip
at a terget 1 meter from you and missed most of the shots :P.

And by the way, with a cone-shaped deviation it wouldn't be just as easy to hit a far away target as it is to hit a target close to you.

Let's say that the target is so far away that his head appears 2 pixels wide on your screen. This would mean that it's impossible to aim in the middle of those no matter how hard you try. Then you use the RMB to zoom and !blam! the head appears 7 pixels wide now and you can aim on it perfectly.

What i'm saying here is that IF it is a cylinder deviation, it would put the emphasis on aiming even more so than a cone deviation.. I think that wouldn't be a "stupid way to make the game", I think it would be a good compromise between a mercyless point&click and normal firing cone.

[evilzucchini]

Re: Firing Cone

Nosekill,

If the bullet leaves your gun in a cone shape, the deivation from the axis of fire is going to increase with distance (assuming the deviation on the horizontal and vertical axes from the axis of fire are non-zero).

If it leaves your gun in a cylinder shape, the deviation from the axis of fire is constant (if you exclude bullet drop. However, bullet drop effects both cylinder and conical firing patterns so it can effectively be removed from the equation) regardless of the distance you are firing.

This would actually make hitting distance objects easier because your deviation does not get exaggerated with distance while in the conical firing pattern your deviation is directly proportional to the distance.

Keeping the conical shape as opposed to the cylindrical shape puts more emphasis on reducing your deviation as much as possible. So I don't think it is a good compromise, I think it makes shooting at distance easy.

[NoseKi||s]

Re: Firing Cone

Goody.. so we agree on how the different deviations would work. Thanks for clearing it out for the others too :)

Yes. Cylinder deviation makes it easier to hit far away targets assuming that you always aim very accurately. Which, in my opinnion, is justifiable in a game like this.

With a cone deviation, the chances of hitting the target at a certain distance would be the same no matter how far from the center line of the cone (aiming point) the target is, as long as it is entirely inside the cone.

Still we don't know which method (or maybe a combination of both) is in practice in BF2, so it's hard to make any final conclusions about this.

My point is that the game is working nicely and i'm seeing things in the game that make me believe it's a cone-shaped deviation. And most of all, i like the idea of a cone-shaped deviation that puts the emphasis on careful aiming but still doesn't turn the game in to a "whack a mole" with a military theme :) I dont't think it's too easy to shoot from a distance in bf2

[vbl]

Re: Firing Cone

Can either of these explain why shooting from the prone position against a prone target (both laying on the ground) is almost impossible with Full Auto/Burst but easy with Single Shot? Even tapping full auto with a carbine rarely hits when shooting close to, and parallel with, the ground. It's almost like the ground is "eating" the projectiles.

[Tenshi]

Re: Firing Cone

No there is only one system here

If you understand how dx does the transforms it makes sense.

Its hard to explain ...even with pictures. But ill try...


There are a few transforms that take place in the rendering pipeline. The first takes the coord system of the object and transforms those to world coords. The Second takes the world coord system and transfroms it to make the player the center...so it rotates and positions the world around the player. Simple.

The last one is a bit abstract but is very simple.

Next, directx creates a viewing fustrum. This is just a pyramid shape where the point is the player. Its extends into the game world. Then dx creates far and near clipping planes. Everything outside of this fustrum is removed.

So what your left with is a pyramid shape with the top cut off.

Next is the odd bit. It takes that shape (and all the geometry in it) and does the final transform. Is turns this shape into a square prism. The result is that near things are made bigger and far things are made smaller. This is the perspective transform.

The parallel bullets are fired through this perspective distorted space.

Mathematically, this bullet path is pressumably simple...but the space it travels through is distored. So the path of the bullets is actually conical.

Does that make sense?

I pressume this is why it appears that the bullets are fired in a tube but travel in a cone.

[Tenshi]

Re: Firing Cone

This dissapeared of the front page in like 20 mins...bump

[skitzo]

Re: Firing Cone

Well, inaccuracy is caused from the constant recoil. OK example time, say that you have a gun. You fire the gun and the recoil makes you jerk the gun. Since you had the gun on the target, by shooting and jerking, your at least alittle off the target. On full auto, you keep firing, so the first bullet is gonna be the most accurate. The constant jerks make you keep getting off target and when you aren't even being able to lineup with the target again, then you won't be able to get back on target. Of course the bullet is straight(not including shotguns) but the constant jerking keeps you off. Of course(to the starter of the topic) there is bullet drop because gravity is present. Gravities rules are that whatever goes up comes down. I agree with you alittle bit. I don't agree that the bullet leaves the barrel in a cone fashion as in a shotgun. Mainly you have to put the thing firing the weapon into view. A human could have problems holding the gun, therefore it struggles to keep it up overtime or if its really heavy, then you would struggle from the weight from the start. Your arm shakes(unless supported), now this will cause you to not be exactly right on the target, but its so small a deviant that you shouldn't worry about it. Now this little deviant could grow depending on distance. Mainly it will keep going straight, but again you wont't be exactly on target. This emphasizes on long range(not with snipers). Over distance on a target that is fairly small, by shooting just alittle off target by the shaking of the arm, that could mean that you missed the person entirey. Snipers are different because with the scope, you can see a person as if he was right up close to you.Therefore the deviant created does not matter because the sniper is enabled to see where the bullet will hit.

This topic is a more or less situation. Half and half.

Edit: Wait this is ingame or is it not? I didn't know if you were talking about real-life or not. If it is than I wouldn't know much because I can't play till Christmas.

[Tenshi]

Re: Firing Cone

The point is that someone said that the bullets leave the gun in parallel. Thats absurd. Ill explain why.

In a hypothetical game (without gravity). Say we make a machine gun. In our game the bullets leave the gun all travelling in parallel. So the possible path of bullets forms a cylinder. This cylinder has a maximum and minimum size. When you fire the gun, the cylinder starts smaller and gets bigger the longer the trigger is held.

So how big should we make the maximum size?

We test the gun by firing at a dude 100m away. We know we are pointing the gun directly at the center of the target. The first bullet hits dead on because the cylinder is very thin.

Lets say we want 50% chance of hitting the dude at full auto. So logically, the cylinder should be big enough so that half the bullets miss the target. Lets say the target is 6ft tall, that means the cylinder should reach a maximim diameter (during full auto) of something like 4ft (say). Thats fine...

...except now lets try to shoot a guy 1 meter away...in full auto the bullets are leaving the gun in a 4 foot wide cylinder. Thats bigger than the character youre playing as. You aim your gun at the dude 1m away...still 50% of the bullets will miss him. Yet hes only 1m away...that dosent make sense.

Thats totally unrealistic and naff for gameplay.

Here you have a gun thats 50% accurate at 100m and 50% accurate at 1m.

[NoseKi||s]

Re: Firing Cone

...except now lets try to shoot a guy 1 meter away...in full auto the bullets are leaving the gun in a 4 foot wide cylinder. Thats bigger than the character youre playing as. You aim your gun at the dude 1m away...still 50% of the bullets will miss him. Yet hes only 1m away...that dosent make sense.

This exactly is one of the things that make me believe it really is a cylinder deviation it the game. When firing the PKM while standing for example, u can really miss most of the shots towards a guy that is standing just 1-2m away from you.

[Tenshi]

Re: Firing Cone

can you shoot round corners?

[WarGimp]

Re: Firing Cone

Oi NoseKi||s... good rational, but you're forgetting something about conical deviation.

It's a probability cone, not an even random spread. The difference is subtle, but very important to your argument. Let me try ta walk ya through this (I'm a bit zoned ATM, tho... fair warning ).

If you know anything about probabilities, you know all about bell curves. Since there's a random chance for a bullet to travel down any path in the cone, you will get a bell curve forming as you fire. The peak of the curve will be dead center on your sights.

In short, the better your aim the better your probability of hitting the target via the cone model.

You can prove this to yourself, if you like. Just oull out any weapon and fire it at a wall for awhile. Go fairly close to it, but not too close. About 12 feet should do. Aim at some part of the texture to help gadge the effects. Try to time your shots to let your gun settle or additive deviation will polute the experiment.

Now, if your graphics are set to high, you should be able to notice that there are more bullet holes twards the center of your aim. There will be spread, and you might get some counter intitive results, but if you do it long enough you'll see what I mean.

You can also prove the existance of the cone model by backing up a bit and repeating. There will be more total spread.

As I say, good thinking. Ya just missed something.