Welcome to symthic forums! We would love if you'd register!
You don't have to be expert in bit baking, everyone is more than welcome to join our community.

You are not logged in.

Hey! If this is your first visit on symthic.com, also check out our weapon damage charts.
Currently we have charts for Battlefield 3, Call of Duty: Black Ops 2, Medal of Honor: Warfighter and Call of Duty: Modern Warfare 3

  • "tttt1010" started this thread

Posts: 23

Date of registration
: Apr 28th 2017

Platform: PC

Reputation modifier: 1

  • Send private message

1

Saturday, June 3rd 2017, 10:51am

Help with bullet drag?

I'm looking at how bullet drag works in BF1 and according to weapon info,

  • Bullet slows down at Bullet_Velocity˛ * Drag m/s



However, isn't drag a force so the unit should be meter/s^2? The drag coefficient for most guns is 0.0025.
Using the selbslader 1916 as an example, 0.0025*800^2=1,600. That means velocity is 800-1600 m/s = -800m/s? That can't be right.


NoctyrneSAGA

PvF 2017 Champion

(9,607)

Posts: 6,965

Date of registration
: Apr 3rd 2012

Platform: PC

Battlelog:

Reputation modifier: 19

  • Send private message

2

Saturday, June 3rd 2017, 11:23am

I don't see any reason why the realistic drag formula wouldn't be used over the simplified one. It wouldn't really be any more complicated to set up in game either way. Bullet positions aren't solved analytically, they're integrated frame by frame from velocity, which is integrated from acceleration.

The numbers make sense too. Just use the drag equation and F=ma, then just solve for acceleration and roll everything that isn't velocity into a single constant, drag.

Instantaneous acceleration = v^2 * drag

For G98, that would be 880^2 * 0.0025 for the first frame, or 1936m/s^2 acceleration, which seems really high, but remember it's applied over a short time. At 60 frames per second, that would be around 32m/s less for the next frame.

For the second frame we'd have 848^2 * 0.0025, which is 1798m/s^2, and -30m/s in the next frame.

For the third frame we have 818^2 * 0.0025, 1673m/s^2, and -28m/s in the next frame.

The bullet would have a velocity of ~790m/s on the fourth frame. I'm stopping here, but the math would keep repeating for each frame.

To get position we just multiply the velocity in the frame by the delta (1/60 for 60fps) and then sum them.

So first frame gives a travel distance of 14.667m, second 14.133, third 13.633, fourth 13.1667, etc.

Summing those we get a travel distance of around 55.6m, for an average velocity of 834m/s for the first four frames. The more frames we calculate for, the more average velocity will be reduced by drag.
Data Browser

Passive Spotting is the future!

With this, I'll rid MGO3 of infestation. Sans bad gameplay MGO3 will be torn asunder. And then it shall be free. People will suffer, of course - a phantom pain.

Reddit and Konami will rewrite the records... And I will be demonized in human memory. But... The thirst for good gameplay that I have planted will infest MGO3. No one can stop it now. The Rebalance Mod will unleash that thirst unto the future.


Are you a scrub?

If it flies, it dies™.

  • "tttt1010" started this thread

Posts: 23

Date of registration
: Apr 28th 2017

Platform: PC

Reputation modifier: 1

  • Send private message

3

Saturday, June 3rd 2017, 3:53pm

thanks

Posts: 274

Date of registration
: Jun 21st 2012

Platform: PC

Location: Moscow, Russia

Reputation modifier: 7

  • Send private message

4

Saturday, June 3rd 2017, 9:47pm

There is also a superb post by Miffyli, with awesome graphical explanation of how bullet drag affects bullet drop.
Sorry for my bad english - it's not my native language and I have difficulties with acquiring speaking/writing practice in my country. If I accidently insult you or say something wrong - I'm sorry, you can feel free to correct me.

This post by "samsmith150" (Saturday, July 29th 2017, 1:49pm) has been deleted by user "Miffyli" (Saturday, July 29th 2017, 2:07pm) with the following reason: ad