Home » MODDING HQ 1.13 » v1.13 Coding Talk » Lower bullet damage with distance
Lower bullet damage with distance[message #292548] Sat, 22 October 2011 01:15 Go to next message
usrbid

 
Messages:1580
Registered:December 2008
Not sure if NCTH does that already, bullets will do less damage the more they travel through air.

There are a variety of factors, but I think it can be simplified that a bullet should gradually do less damage based on how far the impact area is from the shooter.

For example at the weapon's maximum range, the one displayed when you hover over the weapon, the damage could be 75% or 66%. At double the distance this could drop to 50% or 25%. This is a little extreme in real life but should make the effect noticeable in game.

Another positive effect is that sniper rifles with a huge range will distinguish themselves in game as their damage is not reduced compared to other weapons.

I had this idea while I was slaughtering gangsters in the UC subway like cattle with hollow point pistols. I was able to one shot kill bad guys way beyond the gun's range dropping enemies like flies in a circle around me, it felt surreal.


Re: Lower bullet damage with distance[message #294064] Wed, 23 November 2011 23:23 Go to previous messageGo to next message
Cell

 
Messages:669
Registered:February 2011
User deleted
Re: Lower bullet damage with distance[message #294073] Thu, 24 November 2011 11:22 Go to previous messageGo to next message
Inkompetent

 
Messages:31
Registered:November 2011
Location: Sweden
Acceleration through free-fall is pretty irrelevant. We fight at pretty much flat terrain, so potential energy (bullet's position above ground) is such a tiny, tiny decimal it can be discarded for the purposes of bullet damage.

The bullet's drag factor (i.e. how fast it decelerates due to air resistance and drag) and muzzle velocity are the two interesting base factors.

Then of course one will have to multiply that in some way with the bullet's estimated penetration-capability and damage against soft tissue.

It can be done as simply or complex as one want really.

Essentially we could use the current damage system, and just include the drag factor to mess with long range damage.
Re: Lower bullet damage with distance[message #294076] Thu, 24 November 2011 13:28 Go to previous messageGo to next message
usrbid

 
Messages:1580
Registered:December 2008
Yo Monade, the amount of damage a bullet does depends on (as far as I know):
- bullet weight
- bullet speed (at a specific distance)
- bullet shape
- target medium

From weight and speed you will (probably) be able to calculate the energy the bullet has. However as far as I know the energy is not the best measure to determine damage. There is something called the Taylor KO Index (look on Google), which is better in predicting effect on impact.

The weight, speed, and energy for most bullets you can find on Wiki (or on the package when you purchase them e.g. Hornady is good about that).

For example shooting a typical 9mm and 45 ACP under same conditions, it is quite possible the 9mm will have more energy compared to the 45 (I haven't verified that), however from experience the 45 will have more destructive effects (I believe because the bullet is bigger and heavier).


A hollow point will penetrate less compared to a full metal jacket. For example shooting a 45 HP and FMJ under same conditions the FMJ will travel further in the medium.

Here is why energy alone is not a good measure. A 9mm FMJ will travel ~4 feet through ballistic medium (no denium in front), while a 45 FMJ will make it (I guess) ~18 inches (maybe more, but not 4 feet). The 9mm travels further because the bullet is smaller and there is less friction to slow it down.

However a front to back pass through is not as desirable. Depending what organs (if any) were damaged, this can be survivable. A 45 HP will lose all its energy inside the medium and cause a tremendous temporary stretch cavity and leave a huge wound channel which in turn speeds up blood loss.


Bullet speed at muzzle (right in front of the gun) is determined by the barrel length (using same bullets). Too short of a barrel doesn't allow all energy from the powder to be transferred on the bullet. Too long of a barrel (unlikely case) will eventually slow down the bullet due to friction in the barrel.

For example shooting a 45 ACP through a 5 inch barrel will have the usual 890 ft/s at muzzle, shooting through a 3 inch barrel can make the speed drop below 800 ft/s. US soldiers in Iraq prefer 20 inch barrels for 5.56 NATO as the longer barrel gives the bullet more speed / destructive power.


Bullet speed at target is influenced almost entirely by air resistance, which in turn needs humidity, barometric pressure etc. For example most modern firearms e.g. Glock, H&K USP will discharge safely completely submerged in water, however the bullet travels about 2 1/2 feet in water.

Another example, the faster a bullet goes the more air resistance it will encounter. Speeding up a bullet to somewhere between 3,000 to 4,000 ft/s will result in the bullet disintegrating in mid air, it breaks up into pieces (assuming normal bullets, not tungsten core). That's why small arms ordinance typically doesn't go beyond ~3,000 ft/s.


Bullet drop is mostly an aiming challenge. The more a bullet drops, the higher you need to aim (or adjust the sights). For example 7.62x39 WP has a drop of ~40 inches (don't know the exact number) at 300 yards. However if you compensate for the drop by aiming higher, the bullet will hurt the target, no difference.

How much a bullet drops depends on its weight and the energy it has. Heavier and slower bullets will drop more.


The shape of the tip of the bullet will influence how much air resistance a bullet has. This is why hunting rounds are typically polymere (plastic) filled hollow points as you want good flight characteristics but destructive power at target. The plastic tip is no significant hinderance for hollow point expansion.

The shape of the nose of the bullet, the area immediately following the very tip, also determines air resistance. This "curvature" of the bullet is called ogive. This is why rifle bullets are shaped differently than handgun ammunition, because rifle bullets are designed to better deal with traveling through air over long distances.

The shape of the tail of the bullet will influence stability (wobble) and how well the projectile deals with "closing up the air" behind it, which is called drag. Basically the bullet makes a hole as it travels through the air which creates a (partial) vacuum at its end, which "pulls" the bullet back and slows it down. A boat tail design is typically used for long range high accuracy target engagement as the boat tail (look it up on Wiki) stabilizes the bullet and bleeds of drag well.


Let me know if you have questions.


Re: Lower bullet damage with distance[message #294078] Thu, 24 November 2011 15:50 Go to previous messageGo to next message
Sam Hotte

 
Messages:2031
Registered:March 2009
Location: Middle of Germany
AFAIU all the stuff "how does any projectile transfer its energy to the target" is done already in MAM. So no need to duplicate this, IMO.
I do not know, if MAM considers range in its calculation ("how much energy has been lost flying between muzzle and target due to mainly so called air resistance?"). If not, there - the time of impact on target - is the right place to consider it if you want to have it as complex as MAM.

If you stick to the more simplified current damage system AFAIK "bullet drop" of NCTH is the part that considers range restrictions due to air resistance. I guess that range currently just influences CTH.
You would need something added like "for every tile the bullets goes over effective range its potential damage is reduced by x".
That'd be it, IMHO.

[Updated on: Thu, 24 November 2011 17:32] by Moderator

Re: Lower bullet damage with distance[message #294081] Thu, 24 November 2011 16:00 Go to previous messageGo to next message
Inkompetent

 
Messages:31
Registered:November 2011
Location: Sweden
MAM does consider range. Bullets in MAM loses energy over distance, meaning you need minimum 7.62x51/54mm for any longer range shots.

How is damage-falloff set up in that case though? Per ammo type per gun I suppose?
Re: Lower bullet damage with distance[message #294083] Thu, 24 November 2011 17:44 Go to previous messageGo to next message
Cell

 
Messages:669
Registered:February 2011
User deleted
Re: Lower bullet damage with distance[message #294084] Thu, 24 November 2011 17:46 Go to previous messageGo to next message
Sam Hotte

 
Messages:2031
Registered:March 2009
Location: Middle of Germany
I do not know how MAM takes the distance a particular bullet has covered into account.
But since you know that MAM does consider it, Monade no longer needs to make up his mind about physics *here*: Just use MAM (and improve its calculations if needed).
The more complex physics about what a bullet really does and how it applies its energy to inflict damage to flesh and bones are already there. To me it seems more logical to dig into MAM and eventually improve it if one wants to have the complex physics in JA2 ...
Re: Lower bullet damage with distance[message #294085] Thu, 24 November 2011 17:50 Go to previous messageGo to next message
Cell

 
Messages:669
Registered:February 2011
User deleted
Re: Lower bullet damage with distance[message #294088] Thu, 24 November 2011 20:21 Go to previous messageGo to next message
Sam Hotte

 
Messages:2031
Registered:March 2009
Location: Middle of Germany
Monade
The point is just we have no dynamical calculation of damage loss with distance.


But we have a dynamical calculation of Damage: MAM. (Let's assume for the discussion MAM would be a physically accurate calculation of each bullets damage depending on weight, form and shape, material etc. - and impact energy)
The only significant influence range has is a loss of impact energy.
MAM already calculates impact energy - but the energy loss the projectile suffers on its way is not calculated dynamically yet.(at least within effective range its not).

So what you need/want is a dynamically calculation of eneergy loss during the flight path. OK.
Given the fact that we do not have a weather and environmental simulation, we could take the very educated guess that the fluid "air" the bullet is flying through is the same in every part of the current tactical secter in game: Humidity, temperature etc. will not be different between two adjacent tiles and they will not change during the (very short) time period our bullet is on its way.
(So BTW your question about the impact of pressure, wind, temperature etc. is answered: They do not have impact in the game as they do not change during a gun fight - so you can take any values you see fit and being reasonable.)

After all, the only factors that then have significant influence on the calculation of a bullets drag (-> http://en.wikipedia.org/wiki/Drag_(physics) ) are its geometry and material and of course its initial speed.
And all those factors should be included in MAM for a good part at least. Cause Geometry of the projectile and its material determine things like tumbling, penetration, deformation etc.

That's why my POV is: If you want dynamically influence of range on damage, start at the point where damage is calculated dynamically; that's much easier than looking at the things from the IMHO wrong end (no offense intended).
Smile

[Updated on: Thu, 24 November 2011 20:26] by Moderator

Re: Lower bullet damage with distance[message #294089] Thu, 24 November 2011 20:56 Go to previous messageGo to next message
Cell

 
Messages:669
Registered:February 2011
User deleted
Re: Lower bullet damage with distance[message #294098] Fri, 25 November 2011 01:27 Go to previous messageGo to next message
Sam Hotte

 
Messages:2031
Registered:March 2009
Location: Middle of Germany
Monade
You missunderstood what i meant with air resistance i want to know a basic value which is equal in all terrains/sectors in-game, something which affect the bullet as soon as its leaves the barrel and therefore the damage on impact as well as range.

Do not think i misunderstood this point: this basic value in the drag formula is the drag coefficient multiplied by the bullet's area that is prone to airflow. And those values are directly derived from the projectile's geometric shape (IIRC mainly sharpness and diameter of ogive and length) and velocity.

Quote:
From what was said above additional: What i really want is that damage and range will disappear in UDB/EDB or BobbyRays. And only appear when pressing "F" on tile x or over target y (left-inferior corner of tactical window)

Have you already considered impact on gameplay of this "wish"? It would make gun comparison a very, very tedious work, nearly impossible for somebody not being familiar with guns and different calibres.
Re: Lower bullet damage with distance[message #294100] Fri, 25 November 2011 02:05 Go to previous messageGo to next message
Cell

 
Messages:669
Registered:February 2011
User deleted
Re: Lower bullet damage with distance[message #294106] Fri, 25 November 2011 06:55 Go to previous messageGo to next message
usrbid

 
Messages:1580
Registered:December 2008
Monade
Wow thanks Dieter


No problem, any time.

Monade
what if the bullet is a Ricochet?


I am not super sure but I believe the current code doesn't support ricochets. In real life ricocheting does happen more frequently than one would expect e.g. deflection of stone or metal plate and the bullet is still dangerous e.g. you can find a couple NoobTube vids where the shooter gets minor injuries. Personally I ignore ricochets as the chance the bullet comes back at the shooter is abysmal.

Monade
Aiming with subsonic ammunition at distances around 200 is something special than aiming with supersonic isnt it? As said the bullet drop is drastic compared to supersonic.


A heavy bullet will drop more compared to a lighter one given the same speed. That is also why hunting ammunition tries to be as fast as the bullet supports before disintegrating to make the bullet travel further in less time which in turn minimizes bullet drop and makes aiming easier.

This vid explains something else (how to zero your AR sights) but it visualizes very well how aiming and bullet drop works and will help you to actually see what we are talking about.

Monade
One thing at the end: Air resitance is defiend by alot of parameters (wind, temperature, pressure...) which average value could be used for this?


In principle you can use any values you like e.g. averages at sea level, as the differences are almost negligable at shorter distances e.g. less than a mile, meaning air does a somewhat bad job trying to slow down a bullet. This is because a bullet travels comperatively slow e.g. to atmospheric entry where you need to become creative managing air resistance, and air is comparatively thin e.g. to water.

Monade
Can someone place a complete formula best with an example? Bullet x fired from weapon y has z engery left after xyz tiles.


You can get this information either from the Wiki (each caliber has the muzzle velocity and energy) for a "default" barrel length (usually 16 inch) or from the ammunition manufacturer (on their Web site or on the box the bullets come in). Here is something from Hornady for example. This is one of the free on-line calculator resources.

To get the velocity at a specific distance, there are many on-line ballistic calculators. You enter the bullet characteristics and shooting conditions, and the calculator will produce the data for a specific range.

Edit: None of the stuff on JBM is currently working, come back after the weekend, I am sure they are going to fix it soon, they have been providing this service for over a decade, must be a technical glitch.

[Updated on: Fri, 25 November 2011 07:18] by Moderator



Re: Lower bullet damage with distance[message #294107] Fri, 25 November 2011 07:20 Go to previous messageGo to next message
Cell

 
Messages:669
Registered:February 2011
User deleted
Re: Lower bullet damage with distance[message #294112] Fri, 25 November 2011 09:46 Go to previous messageGo to next message
usrbid

 
Messages:1580
Registered:December 2008
Monade
The vaccum behind the bullet has more affect on velocity than air resistance?


Probably not. The partial vacuum, or lower air pressure, behind the bullet will have *some* effect on slowing the bullet down by itself.

More importantly the vacuum will create a turbulence making the bullet "wobble" in mid air. The more unstable a bullet is during its flight path, the less well the nose of the bullet deals with "parting" the air, essentially resulting in higher air resistance.

Monade
Yes online ballistic calculators are nice but what about a formula? I meant something like we have in game to calculate damage/force/energy on x tiles. That is what the topic is about or not - "Lower bullet damage with distance"? So what about a formula?


Maybe you will get lucky and some of the on-line calculators will use a Java Script (.js) file to do the calculation on the client computer (as opposed to executing the calculation on the server and only sending the text result to the client browser).

Maybe some of the on-line calculators will provide their formulas to the user to demonstrate the quality of their calculation.

If we get really lucky, maybe someone will just post it here on the board.

If you feel like it, you can look through some of the on-line calculators and do some research to find a formula.


Re: Lower bullet damage with distance[message #294127] Fri, 25 November 2011 15:31 Go to previous messageGo to next message
Sam Hotte

 
Messages:2031
Registered:March 2009
Location: Middle of Germany
Monade
[Well you said its already included in MAM. Thats to 50% true its a static value BUT the point is its not dynamic calculated in-game for travelled range now. Either with MAM or latest raw 1.13. Therefore i thought you missunderstood something.

Then the missunderstanding seems to be on your side, because i claimed that the information of the geometric shape of different bullets should already be in MAM avaialable so that you would be able to derive the drag thingy from it.
But never mind, this is JFTR.

Quote:
So back to topic and back to drag coefficient. Can someone place a complete formula best with an example?

There is a typical Cd (Cw) of a small, non-rifle calibre bullet at subsonic speed given in wikipedia.
You could start with that and a calibre like 9x19mm.

As for air density I'd use basic barometric values (0
Re: Lower bullet damage with distance[message #294155] Sat, 26 November 2011 18:07 Go to previous messageGo to next message
Cell

 
Messages:669
Registered:February 2011
User deleted
Re: Lower bullet damage with distance[message #294156] Sat, 26 November 2011 18:45 Go to previous messageGo to next message
Sam Hotte

 
Messages:2031
Registered:March 2009
Location: Middle of Germany
Monade
Sam_Hotte
As for air density I'd use basic barometric values (0
Re: Lower bullet damage with distance[message #294359] Thu, 01 December 2011 16:14 Go to previous messageGo to next message
Cell

 
Messages:669
Registered:February 2011
User deleted
Re: Lower bullet damage with distance[message #294387] Fri, 02 December 2011 12:11 Go to previous messageGo to next message
Cell

 
Messages:669
Registered:February 2011
User deleted
Re: Lower bullet damage with distance[message #294424] Sat, 03 December 2011 16:30 Go to previous messageGo to next message
Cell

 
Messages:669
Registered:February 2011
User deleted
Re: Lower bullet damage with distance[message #294490] Mon, 05 December 2011 19:05 Go to previous message
Cell

 
Messages:669
Registered:February 2011
User deleted
Previous Topic: Self-Transforming Items (Pre-Project Discussion)
Next Topic: How does % condition of the silencer work?
Goto Forum:
  


Current Time: Sat Jan 20 01:13:15 EET 2018

Total time taken to generate the page: 0.01555 seconds