Vehicle collision damage is completely insane - again

[RosieMcCattail]

Changed damage calculation to be impulse based, instead of being based on deformation energy. Damage is generally lowered across the board for larger vehicles.

as per #5926

This is madness. This has sometimes (it has been tweaked back and forth many times before) happened before, but with the new code - I don't know what to say, even

This is from hitting two ordinary passenger cars in a 19 ton rolling tank at 32!!!!!!!!! KM/H!! For the parts that are relatively deep into the vehicle!

I've had a military grade plating go to magenta health by rolling over TWO corrosive zombies - that's it, just two zombies. Can you even imagine a tank having its armor peel off from smashing into bears or some such?

I'm asking for at least some input, please, this is absolutely nuts, the vehicle is like made of glass, minor bumps into zombies (without killing them) constantly lead to platings going yellow, I have to repair the car almost every time I auto-drive it to any place.

[scarf005]

that's certainly weird, thought #5926 made vehicles more durable. also pinging @Retagin for input

[RosieMcCattail]

That's not wierd in and of itself, considering that in many years of me playing different branches of Cata I've seen vehicles go from almost completely invulnerable to breaking in two from hitting a bush (I remember many years ago my armored bla bla super duper death mobile literally dropped a tile in the middle of it from hitting one military supply crate - the frame just went pop and everything on it followed suit). It's not that it's wierd, it's that IMO you (not you personally) have cranked it a little but farther than 11 this time. And then I cooled down and searched the PRs for vehicles and saw that vehicle code has been (again) rewritten with the stated result of making vehicles sturdier. Well, here's my input on that, please consider tweaking it more

sidenote - answering your question in another thread that I got asked not to derail - yes, the government has decided that its citizens would be better off not using Discord anymore. Unfortunately, I don't know the ramifications of using VPN for unencrypted traffic and loggin into places, so I decided to not risk it until I find out.

[Retagin]

The vehicle damage system is still messed up in base premise. Simulating out believable damage from a collision requires alot more data than the game has or that we would ever really want to put in there, because it quickly starts becoming a finite element analysis program.
I would like to think what I did was effectively emergency first aid, mostly focused on preventing scenery objects from causing tanks and APCs to explode.

The maximum damage that a collision with a creature can inflict is based on the creatures max health, with some modifications from armor and if you have a ram. This has the obvious issue that as evolution goes up and creature inevitably have their hitpoint values skyrocket, that they will be dangerous to hit. This also makes cars thrown by hulks or other monsters incredibly dangerous.
The alternative is once again to effectively make a finite element analysis program to determine how much damage each collision deals. Mass is not consistently done across monsters, no elasticity, material properties, etc.

Vehicles to vehicle collisions get the worst of this. There is not currently good data or variables in the game to determine collision time or distance which are required to actually do collisions well. I toned down and mitigated shock damage, but to be frank shock damage likely needs to be completely overhauled or removed.
The values the game uses don't lend themselves well to simulating collisions, but at the same time asking modders to add in full proper engineering specs of materials/vparts they add is also probably not going to happen.

As far as critter collisions causing to much damage goes, the immediate answer that pops into my head (and what my noggin was whispering to me while writing the collision damage PR) is that most of the vehicle parts need to be modified/buffed. The damage resistance/soak values for many of those parts is either too low for what it should be (looking at you military composite armor) or has no damage soak at all.
For vehicle collisions, overhauling shock would help I think, but actually getting the simulation to do what we want it to do either requires some very bad estimates, alot of magic numbers, and 2-3 step convergent solver, OR having people add alot more real world material properties to things. I have no idea which would be better.

[RosieMcCattail]

Even if there is good input for the equations that does not mean vehicles should be porcelain made, and I still suspect there are things that could be improved without that data, like damage propagation and plating actually protecting stuff beneath it, which it currently probably maybe does, but you can see the result above.
I've tested ramming a bit at 6 km/h and it's fine, you can plow through a whole city worth of zeds with little to no damage, that does not mean you'll kill them all but they'll get shoved out of the way and you'll get where you wanted to get, so it's fine.
I think part of the reason is the comparative HP/damage reduction values on military/heavy duty stuff is way way low, I can understand hatchbacks breaking up when hitting gigantic masses of bones that the jugs are, but a tank-like thing should not.

The plating certainly does its job poorly, like the first thing to go when I hit a jug are my mirrors which obviously have tiny HP but they're located in the 3rd row of tiles, batteries suffer too, in general all low hp components get killed, which just means the plating isn't protecting parts from damage like it says it should. I don't think there's any reliable way to simulate concussion damage rocking the inside of the vehicle so I suggest toning down damage propagation significantly.

As for damage being linked to monster HP, that's funny, because I play at 150% moster resilience, that should explain some stuff. However, raising monster HP should be a challenge to the player, not make vehicles into a porcelain vase, so unless vehicle HP gets linked to monster resilience I don't really think it's that great of an idea.

Oh and also as a faraway plan consider that normal (not giant size zombies) probably can't reach stuff that's on the roof? Like a normal zombie should not be able to smash solar panels of a giant truck just by smashing its sides.

[Retagin]

The changes I made with my prior PR included negating shock damage under a certain velocity (6 m/s. Yes its very fast, but the game tries to accelerate the vehicle to the full speed it would get to, then hit things so pushing things requires a couple workarounds.), actually making armor apply to shock damage, capping terrain/critter shock damage and a few other things that escape me at the moment.

Tying critter collision damage to HP instead of mass was mostly a holdover from how collisions with terrain work, and it provided an upper limit to how much damage should be feasibly applicable without magicking up collision time or distance numbers (Would be adding finite element analysis lite to the game, especially for vehicle to vehicle. I know a bit of fortran and have extensive experience with APDL Mechanical. Its doable with C++, I just don't think it would add enough to warrant the extra overhead.)
Something I am thinking about is increasing the damage applicable to the colliding objects equal to the critters max HP + resistances, but this would result in vehicle collisions with characters almost always being lethal which is not ideal.

Shock damage is Funky (not in a good way), and is especially bad in vehicle to vehicle collisions. Vehicle to vehicle collisions have been generally reigned in somewhat, but shock damage grabing the full initial damage (now minus damage resistance of the impacted part and reduced by impacting with a part with a ram flag!) and then propagating it out hitting part on the vehicle with Damage/(distance ^2) can cause vehicles to instantly pulp over certain sizes. It now discards low results ( 5> damage iirc) but will still result in every part in the vehicle slowly taking a beating.
What I would like to do is base maximum transferable shock damage on a vehicle parts stiffness, but we still dont have a consistant stand in for that. Some objects that should be very stiff have high resistance with low hitpoints, but sometimes things that are just difficult to damage (modded goo parts, etc) are also given high damage resistance. I may give it a try at some point, but life and job stuff have currently caught up with me, and I am still working on iexamine action stuff.

As for vehicle parts, .50 BMG in game does 100 damage and 44 armor pierce and IRL has (generally, buba can always make a hotter load) 18,000J of energy out the barrel. .308 Does 21 damage with 12 AP, with around 3,600J out the barrel. The heaviest vehicle armor we have in the game is the military composite which is notably light military vehicle armor, not tank armor and has DR all 70, cut 95, and stab 88. Military composite armor is from my understanding a stand in for APC armor and equivalent (MBTs would have a modern Chobham armor equivalent, which can bounce 120mm cannon fire). APCs and the like tend be penned by 12.5mm (.50 BMG) and up, and not really by smaller caliber projectiles.
Ballistic projectiles are notably better at penetrating armor than most ways of hurting the guy-you-dont-like-over-there. It would make sense for the MCA to have a resistance bullet:75 or something equivalent, but a cut:200 bash:150 stab:150 thermal:50 (Made up numbers, but should still be rather high). Modern high strength materials are incredibly difficult to damage.
The kind of cut damage that you would need to do to instantly cut a person in half just wont do much to 2-3" composite of aluminum, steel and ceramic. A sledge hammer blow that will fold someone in half and kill them will make a loud noise and lightly dent a truck frame. Wont do anything to a thick metal plate.

I am also the kind of person who looks at the plate armor stats and gets grumpy that a 10 strength character can get cut damage through plate armor with a sword. Stuff should make you pretty much immune to the BS. argle bargle.

I might poke at this somewhat, but I am in california with my dying grandfather for the rest of the week.

[RosieMcCattail]

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[Retagin]

What speed were you traveling?

Related note, I am working through a material update PR that has a bunch of follow through changes involved. I am adding a few physical characteristics as optional loads, which will be used to make vehicle collisions less always explody.

[RosieMcCattail]

I WASN'T travelling. The thing threw that sedan at me.

[JohnnyJosda]

How is it in the newer distributions now?