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[Melting Sky]

There is a question I have been trying to figure for a while now which is how does DF determine when an appendage is severed. I've done some of my own VERY primitive testing on the subject just using the arena, and I noticed some trends but have no idea how the math behind it works. Has anyone properly figured this one out?

My observations pointed to a couple of likely mechanics that are involved but this is all based on watching only the most basic of injury trends in the battle logs between various different sized creatures and how their limbs respond to being struck with edged weapons with radically different properties.

I noticed a few things. To begin with only edged weapons appear to sever body parts.

Another thing I noted is that the relative size of the contact area of the blade and the size of the appendage being struck seems to be used in some fashion to determine if the blade is wide enough to cut the body part completely off. The smaller the creature and body part was, the smaller the contact area the weapon could possess and still have a chance to cut the appendage off.

The other thing that seemed to matter was the penetration of the attack. The blade seemed to need to cut both deeply enough and widely enough for the limb to come off. It also seemed like it mattered if the body part was already damaged or not but that may have just been me seeing trends that aren't there in a small group of random results.

If people have already done some real dwarven Science! on this subject I would love a link to it.

[scamtank]

All bodyparts are shaped like x cm³ cubes, the amount depending on the creature's total body volume and the bodypart's RELSIZE. If the edged implement has enough energy behind it, enough penetration depth and a wide enough contact area, it will sever the thing.

If the contact area is smaller than the width of the bodypart, it just ruins all tissue layers without taking the bodypart off. If the penetration is less than the thickness of the bodypart, the open wound stops at that certain depth and the remaining strike energy carries on as blunt force that may still crack bones. If the bodypart itself consists of nothing but rigid, breakable tissues, even a strong enough blunt strike can snap it right off. Creatures made of stone come to mind.

There isn't much nuance in common situations because contact areas, weapon sizes and material weaknesses tend towards "way way overkill".

[Melting Sky]

Thanks for the heads up. It seems like my guesswork was roughly on target. So does the game take into consideration how damaged the limb already is when determining if the blade passes all the way through it or not? I ask because one of the creatures I did a lot of testing on was a Bronze Colossus and despite running a great many battles using various weapons I never once saw a colossus lose a limb on the first strike. It was always after the body part had been hit multiple times that it finally came off. It could be that in the 30 or so fights ran I simply never had a dwarf get lucky on the first shot to a given appendage but it does seem a bit anomalous.

[Urist Da Vinci]

Body parts do accumulate damage, and it might take some time to hack through a solid metal limb. You could use the equations for a colossus arm. I should update the calculator for creature body parts. Main reason why that hasn't happened is that the list could be rather long and repetitive.

Scamtank covered most of the points.

I would add that flexible skin/fat/muscle layers, which bypass blunt damage rather than being destroyed, can't be severed by blunt damage. This allows the bones to be smashed without the limb popping off. I suppose repeated pounding with a morningstar (which has a small amount of edge attack) would eventually sever a person's arm in DF - untested.

Also the head and lower body are somewhat special in that you have to destroy the spine "organ" within before the container part is severed. This is mostly driven by the random chance for which organ is hit.

[Melting Sky]

I would add that flexible skin/fat/muscle layers, which bypass blunt damage rather than being destroyed, can't be severed by blunt damage. This allows the bones to be smashed without the limb popping off. I suppose repeated pounding with a morningstar (which has a small amount of edge attack) would eventually sever a person's arm in DF - untested.

I've actually done a load of arena testing with that particular weapon due to the fact that it is highly unique in the sort of damage it does and it came up in another thread. I originally believed it was impossible for it to sever anything but teeth but then I realized this was simply because I had been doing all my tests on organic creatures that can feel pain. The injuries that morningstars cause tend to be so severe that the creatures collapse and are killed long before that little bit of edged damage can add up enough to actually sever a body part. You have to use it on something like a bronze colossus to see a morningstar sever large appendages. It only occurs after pages and pages of combat.

[Urist Da Vinci]

I would add that flexible skin/fat/muscle layers, which bypass blunt damage rather than being destroyed, can't be severed by blunt damage. This allows the bones to be smashed without the limb popping off. I suppose repeated pounding with a morningstar (which has a small amount of edge attack) would eventually sever a person's arm in DF - untested.

I've actually done a load of arena testing with that particular weapon due to the fact that it is highly unique in the sort of damage it does and it came up in another thread. I originally believed it was impossible for it to sever anything but teeth but then I realized this was simply because I had been doing all my tests on organic creatures that can feel pain. The injuries that morningstars cause tend to be so severe that the creatures collapse and are killed long before that little bit of edged damage can add up enough to actually sever a body part. You have to use it on something like a bronze colossus to see a morningstar sever large appendages. It only occurs after pages and pages of combat.

Tested in the arena with a horde of allied human morningstar users vs a single human husk. The husk quickly ended up as a heavily pulped (but still going!) limbless head/upper body/lower body. Theory confirmed.

[Melting Sky]

Tested in the arena with a horde of allied human morningstar users vs a single human husk. The husk quickly ended up as a heavily pulped (but still going!) limbless head/upper body/lower body. Theory confirmed.

Good to know. I had never actually tested it with an organic creature that could survive the beating for long enough to lose a limb. All my testing was done with Colossi and standard organic units. I assume this means that any edged weapon can eventually sever appendages since the morning star is about as extreme an example as you can get with its tiny contact area and poor penetration.

[scamtank]

So you can deepen existing wounds with new attacks? Huh. I've been wondering about that.

[GavJ]

Do you know how the game determines attack type and severity for flying objects?
Specifically, I am interested in knowing how to choose the most appropriate ammo for different circumstances (or overall if it's all the same except for density or something) for minecart shotguns.

Like, does a silver bar do roughly the same amount and type of damage as a flying silver serrated disc (I don't know if they weigh the same, let's say they do)? Etc.?

[Urist Da Vinci]

Do you know how the game determines attack type and severity for flying objects?
Specifically, I am interested in knowing how to choose the most appropriate ammo for different circumstances (or overall if it's all the same except for density or something) for minecart shotguns.

Like, does a silver bar do roughly the same amount and type of damage as a flying silver serrated disc (I don't know if they weigh the same, let's say they do)? Etc.?

Rough steps:
1. A flying object is a projectile. These are seperate in memory from the attacking creature, and record things like velocity, position, and direction. We get the velocity. Things like traps also use fake projectile data.
2a. If the item has defined attacks (i.e. a trap component, weapon, or certain tools) then one of those is chosen.
2b. If the item doesn't have attacks, treat it as a misc weapon with contact area that depends on size, except that we check the sharpness (melee misc weapons assume zero sharpness i.e. blunt).

So the serrated disc has the potential to sever parts if shotgunned from a minecart.

[Putnam]

I think the "chooses from attacks" also works with the minecart itself for collisions.

[GavJ]

2a. If the item has defined attacks (i.e. a trap component, weapon, or certain tools) then one of those is chosen.

Does that mean that hurling live animals with, say, syndrome venom bite attacks would effectively cause them to randomly insta-bite and infect people they hit as they hurtle past at 100 mph?

Or that if you hurl dragons or clowns, you basically have a mortar (chance of area effect attacks upon impact with creatures)?

[Urist Da Vinci]

2a. If the item has defined attacks (i.e. a trap component, weapon, or certain tools) then one of those is chosen.

Does that mean that hurling live animals with, say, syndrome venom bite attacks would effectively cause them to randomly insta-bite and infect people they hit as they hurtle past at 100 mph?

Or that if you hurl dragons or clowns, you basically have a mortar (chance of area effect attacks upon impact with creatures)?

Nope to both questions. Living creatures are units, not items. Units can slam into eachother, but this only seems to transfer momentum without damage. If you fall on someone from high up, they slam into the floor fast enough to take falling/collision damage.

Dead corpse or body part items no longer have attacks, and are therefore blunt misc weapons.

ONLY trap components, weapons, ammo, or tools can have raws like [ATTACK:EDGE:20000:4000:slash:slashes:NO_SUB:1250]

[Zorbeltuss]

As you said weapons fired from traps have a set speed, but how about Projectile weapons, will the projectiles have that speed, its max speed or something other than that?

/Zorbeltuss

[GavJ]

As you said weapons fired from traps have a set speed, but how about Projectile weapons, will the projectiles have that speed, its max speed or something other than that?

/Zorbeltuss

Well I know that minecart shotguns depend on the cart's speed. 50 impulse ramps = about 75 range, 10 impulse ramps = about 25 range for the same cargo.
Dunno about a moving marksdwarf or other such silliness.