Projectile and ricochet physics simulation, anyone?

[Nuke Dukem]

Disclaimer: OP is not a ballistics, physics, mathematics, networking or any other type of engineer/specialist, so don't grill him too hard if he is spouting nonsense. Thank you.

So, I've recently had this simple idea, but don't know if there are any games (I'm thinking mainly combat simulators similar to the ARMA or SWAT series) that somewhat simulate the physics of projectiles, mainly for close-quarters battles? There aren't any that I know of, but I've never been one to play everything that comes out on the market. Edit: I know about bullet drop and that it's a thing, what I have in mind is more about "stuff bouncing off stuff".

What I'm picturing in my head is a physics implementation that handles bullets and fragmentation grenades, for example:

• For bullets, depending on the ammo type, caliber, angle, velocity, etc. and the material of the surface that the projectile hits, it may ricochet or break down into several fragments. In case of fragmentation, a randomized dispersion pattern is employed with each fragment following its own vector. If and when it collides with another surface, it further reduces its velocity but may ricochet once more until velocity hits zero. If there are too many fragments (think multiple miniguns being fired at once) to compute at once without significantly slowing down the game, the number of fragments and bounces may be lowered.
• For grenades, the situation would be mostly the same as a bullet being fragmented, but probably using a higher number of fragments upon detonation. "Splash damage" must also be accounted for, naturally, but this is not the main idea.
• For a bullet that hits enemy bodies, depending on ammo characteristics, enemy armor, body part hit etc. the bullet may penetrate the body and exit in a straightforward manner with lower velocity, enter one body part and exit another or not exit at all.

The possibilities are endless, as they say, but this is what I can see being used to add a bit of RNG spice to a single-player tactical shooter. Now I say single-player because I image it would be a nightmare to properly sync hundreds or thousands of fragments per seconds across anything other that LAN gaming.

What do you guys think?

 

[droopyRO]

Neah, devs care only about microtransactions, skins and profit. They don't care about gameplay. The days of Rogue Spear, Ghost Recon and even STALKER that had bullet penetration are long gone ...

 

[Vayra86]

Yes, ricochet is not uncommon to the shooter. Quite a few have it, the implementation varies though, the most recent I remember is Cyberpunk even if the implementation is vague. I also remember a few games where weapons upgrades would add ricochet. Also, bullet physics like altitude drop over distance are implemented in games such as Battlefield and bullet penetration was also seen in various games but yes, more older games than new. I believe Metro also has a few of these things.

 

[JWNoctis]

I think Cortex Command, for all its other faults, did something along these lines, but in 2D.

This sort of detailed simulation might make for...something interesting, yes.

 

[Vario]

Disclaimer: OP is not a ballistics, physics, mathematics, networking or any other type of engineer/specialist, so don't grill him too hard if he is spouting nonsense. Thank you.

So, I've recently had this simple idea, but don't know if there are any games (I'm thinking mainly combat simulators similar to the ARMA or SWAT series) that somewhat simulate the physics of projectiles, mainly for close-quarters battles? There aren't any that I know of, but I've never been one to play everything that comes out on the market.

What I'm picturing in my head is a physics implementation that handles bullets and fragmentation grenades, for example:

• For bullets, depending on the ammo type, caliber, angle, velocity, etc. and the material of the surface that the projectile hits, it may ricochet or break down into several fragments. In case of fragmentation, a randomized dispersion pattern is employed with each fragment following its own vector. If and when it collides with another surface, it further reduces its velocity but may ricochet once more until velocity hits zero. If there are too many fragments (think multiple miniguns being fired at once) to compute at once without significantly slowing down the game, the number of fragments and bounces may be lowered.
• For grenades, the situation would be mostly the same as a bullet being fragmented, but probably using a higher number of fragments upon detonation. "Splash damage" must also be accounted for, naturally, but this is not the main idea.
• For a bullet that hits enemy bodies, depending on ammo characteristics, enemy armor, body part hit etc. the bullet may penetrate the body and exit in a straightforward manner with lower velocity, enter one body part and exit another or not exit at all.

The possibilities are endless, as they say, but this is what I can see being used to add a bit of RNG spice to a single-player tactical shooter. Now I say single-player because I image it would be a nightmare to properly sync hundreds or thousands of fragments per seconds across anything other that LAN gaming.

What do you guys think?

Nearest I've seen is Sniper Elite series.

 

[Dr. Dro]

Yep, I can vouch for the Sniper Elite games in higher difficulties, it has some of the most accurate ballistic simulations. Very challenging to play - I prefer the linear bang bang shooty difficulties

Shame Rebellion went greedy with the new zombie game. But the mainline SE games are still pretty awesome, at least up to sniper elite 4.

 

[Nuke Dukem]

Yes, ricochet is not uncommon to the shooter. Quite a few have it, the implementation varies though, the most recent I remember is Cyberpunk even if the implementation is vague. I also remember a few games where weapons upgrades would add ricochet. Also, bullet physics like altitude drop over distance are implemented in games such as Battlefield and bullet penetration was also seen in various games but yes, more older games than new. I believe Metro also has a few of these things.

Yeah, I didn't specifically mention bullet drop because I know this much exists and what I'm thinking is more about close-quarters battle. Maybe I should've mentioned it explicitly. I'll add that in.

Nearest I've seen is Sniper Elite series.

Thank you, I forgot to mention that! I've never played those but I've seen gameplay and know what it's about. Just the slow-mo cinematics I had in mind at one moment!

Think about it - you raid a dilapidated building to take down some terrorists, crap hits the fan, someone lobs a frag grenade at you, you dodge it by jumping in the adjacent room, thinking you're safe, only to see a big red "MISSION FAILED" screen two seconds later. A slow-motion cinematic then plays, showing you that the wall between you and that grenade had two bricks missing and a single grenade fragment had the fortune of flying through one of the holes and hitting you dead in the noggin. Fun stuff!

If big studios haven't aren't using stuff like this anywhere, perhaps they don't find it would prove to be popular. I'm not going to argue with that, most people probably won't care. However I can see niche games or mods handling this.

 

[Dr. Dro]

If you never played, pick up Sniper Elite V2 remastered as a starting point. It's a pretty great game. I also have fond memories of Sniper Elite 3. Been years... should replay sometime

 

[Count von Schwalbe]

Wouldn't be that hard in a multiplayer game. AoE effects are already modeled (grenades), so it would be a matter of applying that to every bullet impact. Probably a logic where an impact angle greater than, say, 60 degrees only causes spalling. This would take the form of a small AoE effect with RNG to decide if damage was taken.

At lower angles it would be a matter of mirroring the vector, applying a few degrees of randomness to the angle, and reducing damage (and increasing drop, if modeled).

The terminal ballistics would be much harder. Bullets are weird, especially long narrow rifle bullets.

Spoiler: A little gross

I heard a story of someone shot in the upper left shoulder, and the bullet exited their body above their right hip, on the front. The bullet turned both down and around. IIRC it was a US soldier in Afghanistan, shot by an AK.

There is a lot of arguments about how bullets actually incapacitate people, over and above the basic "made a hole". It is not an exact science, let alone being easy to simulate.

 

[lilhasselhoffer]

So...the closest "thing" is Havok physics near as I can tell. Now that I've said that...I'm going to recommend you a game that's about 5 years out of vintage, perpetually beta, and should give you something closer to what you need. Warframe.

Most guns are either hitscan or single projectile...until you break out the mods. Slap on a penetration mod, and you can shoot through enemies...the catch being it's basically a projectile sized protrusion of defined size....so instead of an energy calculation you get hit+3 meters which can be anywhere between 1 and 10 enemies. The other catch is bouncing projectiles. There's an old school flak cannon style projectile launcher you can use to charge up, then turn a hallway into a swiss cheese factory. Best of all, none of this is really physics based...it's largely RNG. This means the flak cannon is basically a bouncy random thing...along with all ricochet calculations. As such...less than useful to do something like a trick shot and more a random splash of free damage


This sounds like glowing endorsement...but please take it with a huge grain of salt. The game itself is vast as the ocean and shallow as a puddle. The tutorial sucks. You do get free to play...but you'll need slots to start carrying gear so be warned that you'll quickly hit the limits of what "free" really offers.


Now that I've said my piece...what about the other stuff?
Stug - throws globs of toxic goo very dependent on physics
Drakgoon - "shotgun" type bouncing projectile launcher
Kuva Bramma - Think Rambo. Bomb glued to arrow, dependent upon physics
Literally anything else - slap on a penetration mod

My only caution in Warframe is that the movement+kill loop is 30 seconds of perfect. The surrounding hours of grind, RNG rewards, potentially not knowing what to do, and frustration about FOMO is what...should compel new players to decide early how deep the game can get its hooks into you.

 

[Macro Device]

the most recent I remember is Cyberpunk even if the implementation is vague.

It's unrealistic to put it mildly. Rather a cheat mechanic allowing for easy kills than something at least lowkey sane. You just hide in a random bush and shoot with close to no aiming and still a lot of damage output to be seen.

 

[ty_ger]

For single-player, sure. For multi-player, it probably should be avoided. There are too many netcode/timing issues and also exploiting netcode could be a problem. Imagine a cheat which eliminates or amplifies the area damage. How would you police that?

 

[unwind-protect]

I need a library that computes projectile paths taking into account:

• Drop over distance
• Slowdown, including the complications during the transonic phase when the projectile does from supersonic to subsonic. Physics go kinda crazy there

Differential equations come in here, so a library that doesn't just iterate would be nice to have.

 

[Nuke Dukem]

Wouldn't be that hard in a multiplayer game. AoE effects are already modeled (grenades), so it would be a matter of applying that to every bullet impact. Probably a logic where an impact angle greater than, say, 60 degrees only causes spalling. This would take the form of a small AoE effect with RNG to decide if damage was taken.

At lower angles it would be a matter of mirroring the vector, applying a few degrees of randomness to the angle, and reducing damage (and increasing drop, if modeled).

AoE as in Age Of Empires?

I'm not sure you and I have quite the same thing in mind regarding the actual particles, randomness and synchronization, but I'm not going to argue about it, it's not that important.

The terminal ballistics would be much harder. Bullets are weird, especially long narrow rifle bullets.

Spoiler: A little gross

I heard a story of someone shot in the upper left shoulder, and the bullet exited their body above their right hip, on the front. The bullet turned both down and around. IIRC it was a US soldier in Afghanistan, shot by an AK.

There is a lot of arguments about how bullets actually incapacitate people, over and above the basic "made a hole". It is not an exact science, let alone being easy to simulate.

I've heard and read similar stories regarding certain calibers and ammo, that's exactly why I had that in mind.

My logic with simulating that (without simulating bone and organ structure) would be something like:

• hit arm -> 66% chance of exit, vector is 0-15% off in a random direction
• hit leg -> 33% chance of exit, vector is 0-15% off in a random direction
• hit torso -> 50% chance of exit, point of exit is randomly selected from a point in a radius drawn around the point of entry, vector is random
• hit head -> 25% chance of exit, vector is 0-15% off in a random direction

Rudimentary, I know, but it's a start.

something something Warframe. something

... The surrounding hours of grind, RNG rewards.... how deep the game can get its hooks into you.

Anything multiplayer I try to avoid like the plague for the time being. Last time I played online was 4 years ago when I was in COVID quarantine. Started out with a little... in the end it turned out I'd clocked in ~400 hours in 7 weeks, 5 of those going to work and having something resembling a life. That's a me problem, however -- thank you for the suggestion

 

[Frick]

What do you guys think?

Neah, devs care only about microtransactions, skins and profit. They don't care about gameplay. The days of Rogue Spear, Ghost Recon and even STALKER that had bullet penetration are long gone ...

I think this is one of those times when stuff like that simply isn't very interesting unless it's a very specific game.

PLUS, do you also want accurate bullet wounds? Because that is what follows with accurate bullet physics, and that is very much not fun. Otherwise why would you want to simulate fragmentation?

 

[ty_ger]

AoE : Area of Effect
Splash damage, for example.

 

[Nuke Dukem]

AoE : Area of Effect
Splash damage, for example.

One of those times when not event with the Internet would I have guessed, thanks.

PLUS, do you also want accurate bullet wounds? Because that is what follows with accurate bullet physics, and that is very much not fun. Otherwise why would you want to simulate fragmentation?

A little quick to jump to conclusions, aren't we?

 

[lilhasselhoffer]

AoE as in Age Of Empires?

I'm not sure you and I have quite the same thing in mind regarding the actual particles, randomness and synchronization, but I'm not going to argue about it, it's not that important.



I've heard and read similar stories regarding certain calibers and ammo, that's exactly why I had that in mind.

My logic with simulating that (without simulating bone and organ structure) would be something like:

• hit arm -> 66% chance of exit, vector is 0-15% off in a random direction
• hit leg -> 33% chance of exit, vector is 0-15% off in a random direction
• hit torso -> 50% chance of exit, point of exit is randomly selected from a point in a radius drawn around the point of entry, vector is random
• hit head -> 25% chance of exit, vector is 0-15% off in a random direction

Rudimentary, I know, but it's a start.



Anything multiplayer I try to avoid like the plague for the time being. Last time I played online was 4 years ago when I was in COVID quarantine. Started out with a little... in the end it turned out I'd clocked in ~400 hours in 7 weeks, 5 of those going to work and having something resembling a life. That's a me problem, however -- thank you for the suggestion

Point 1, Warframe doesn't require anybody else. If you are willing to grind, you can have all your friends move on...and still effectively play the game.

Point 2....Rivens.
Let me be less obtuse. Warframe introduced a mechanic whereby you can get a "Riven" to modify a gun. It's basically an RNG surprise box, consisting of 2-3 good things and 0-1 bad thing. One of these bad things can be projectile flight speed. If you don't already see where I'm going then you're going to regret it. Somebody got a -90% projectile speed modifier, and there are a few mods that naturally slow projectile flight. This is the fun part...slap them on a gun that produces about 20 projectiles and go to town. Because the projectiles fall at gravity's speed, you can literally create a swarm of bullets that will break the fourth wall an kill your computer. Think FPS tank, slideshow, then crash. Note that these are simple and stupid projectiles...which aren't even yet bouncing everywhere.


What you are now asking is that upon contact with a body the projectile takes a new and semi-random direction, that the projectile itself might not need said calculation if "there are too many" bodies already being calculated, that the projectiles themselves now have to be non-hitscan...because this would effectively make fragmentation and scattering of just a few bodies in a scene require instantaneous values for up to multiple bounces, and that all of this is going to somehow fit into a burst of netcode that won't crash your computer.


....maybe if you could dedicate like 90% of processing to the physics, 2% to the graphics, and 8% everything else. Think every single bullet doing its own threaded calculations...just to prevent a crash due to having too much. That's...well, Superhot without the time cheat.

 

[bonehead123]

large caliber jacketed hollow points...'nuff said

 

[Count von Schwalbe]

AoE as in Age Of Empires?

Area of Effect. So each bullet impact would have the same simulation as a grenade blast, but tiny.

Grenades would also have a much larger area of danger, but with a percentage chance of not getting hit at all. IRL, the US M67 fragmentation grenade kills with blast effect up to 5m, but has casualty effect up to 15m. So damage dealt up close, and less damage with chance of no damage a little further away.

In terms of simulation, I wouldn't show each fragment, except in a game like SE where you can do slo-mo. Just RNG for damage taken or not, in addition to the regular effects of the grenade, and a bullet impact would simply smaller version of the same thing.

Generally speaking, grenades only have a large performance impact when there are visible particle effects, not from the damage calculations. Unless you are in a voxel world game...