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Author Topic: Combat mechanics: thickness/mass?  (Read 523 times)

kiwiphoenix

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Combat mechanics: thickness/mass?
« on: April 14, 2019, 09:30:23 am »

Hello, modding crowd.

Been trying to implement a more distinctively tiered system of armour to my current project.
Specifically, am struggling to implement a flexible armour that when made of iron can catch light steel projectiles but is penetrated by heavier ones.

Have been trawling for info on combat mechanics, and found several useful formulae and tools.
But something seems... off. Can't find much regarding how armour size/thickness/mass plays into things, which is kind of critical.
After all, it's well known that big enough creatures can have adamantine-proof megasocks.


As things stand, the formulae on the wiki say that my armour should take 85 momentum to fracture. But in tests, I'm seeing full penetration with as little as 7.
That literally doesn't seem sufficient to penetrate the skull and into the brain, but still sails through iron mesh that on paper should stand up to blows up to 12x harder.


Does anyone happen to know the mechanics well enough to fill in these blanks?
« Last Edit: April 15, 2019, 11:47:07 am by kiwiphoenix »
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Sver

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Re: Combat mechanics: thickness/mass?
« Reply #1 on: April 14, 2019, 12:19:39 pm »

With what meager info I could gather, the thickness of a single armorpiece matters very little within a sane range - that range implying the weight of the armorpiece does not immobilize the wearer. The reason for it is that an armorpiece is treated as a single layer, and most of the combat mechanics are only concerned with the degree of damage a layer suffers (e.g. bruised, dented, fractured etc.) and not its thickness. In the end, it is much more efficient to have, say, two breastplates over each other (which would require removing the [SHAPED] tag) than one breastplate modded to be twice as thick - because, with two breastplates, the outer one will soak most of the damage until it is broken, and only then the second one will be exposed to damage.

The exact values where layer thickness actually starts to matter for penetration depth at least start at 75 and above, I presume. Judging by the fact that the muscle tissue is about this thick, and appears to be capable of preventing damage to the bone sometimes.

Could you share your calculations on fracture momentum?
Also, what materials were used in testing? In general, the most important factor in layer damage is the relative strength of materials.
« Last Edit: April 14, 2019, 01:09:23 pm by Sver »
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DF Combat Reworked
The force pulls neck, doing nothing! Also, armor matters, weapons are distinct, organs hurt and other stuff.

peasant cretin

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Re: Combat mechanics: thickness/mass?
« Reply #2 on: April 14, 2019, 11:19:42 pm »

Dunno if the 2013 How is armor thickness/weight determined? thread was being referenced here. If so, ignore. If not, click.

kiwiphoenix

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Re: Combat mechanics: thickness/mass?
« Reply #3 on: April 15, 2019, 11:44:14 am »

...the thickness of a single armorpiece matters very little within a sane range... combat mechanics are only concerned with the degree of damage a layer suffers...
Hm. Unfortunate, but it is a very Dwarf Fortress-y kind of problem to have. Sometimes I forget that this game doesn't actually model the universe down to a molecular level.
...much more efficient to have, say, two breastplates over each other...
Yeah, but I want any changes to apply equally to random NPCs. In fact, it's a major goal for baddies to be much more dangerous; wars should be tense and tragic, rather than goblinite harvests.
...exact values where layer thickness actually starts to matter for penetration depth at least start at 75 and above...
That would explain why low-velocity shots are still able to punch through even LAYER_SIZE 30 armour, but can't touch the brain: skin, fat, and >100 thickness of muscle and bone collectively do the job that a single layer of iron can't.
Thanks for the input!

Could you share your calculations on fracture momentum? What materials were used in testing?
Yeah, of course. If you're interested, here's the nitty-gritty:
Spoiler (click to show/hide)
So as far as I can tell from the existing research, this armour should at least be able to stop small steel darts. But in practice, that's not the case at all, which just does my head in.
Either something major has been overlooked, or I've fucked up something simple. Given both DF and myself, either is possible.


How is armor thickness/weight determined?
Hadn't seen it, thanks for the link - always fun to see other peoples' tinkering. Was referencing that idea, though, yeah, since it proves that penetration depth is being calculated at some point.
The thread's main takeaway was to play around with COVERAGE>100. Never been a fan of that solution, though. Enjoy using COVERAGE 97-99, to simulate joints/weak links/etc, and generally ensure that battle is never completely safe.
Guess it is an option, though, if all else fails. It'd be less jarring for armour to have no gaps than for it to part like butter against slightly stronger materials.
« Last Edit: April 15, 2019, 12:08:35 pm by kiwiphoenix »
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Sver

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Re: Combat mechanics: thickness/mass?
« Reply #4 on: April 15, 2019, 01:34:42 pm »

Yeah, but I want any changes to apply equally to random NPCs. In fact, it's a major goal for baddies to be much more dangerous; wars should be tense and tragic, rather than goblinite harvests.

The main handicap goblins suffer from when facing an average player's militia is not the items, though - it's the skill difference first and material difference second. Steel will always beat iron; and a dwarf who is near-Legendary in all combat skills will slay average invading troops (who appear to have Competent level in a weapon skill of choice and Novice in all other combat skills) by dozens, additionally helped by the dwarven ability to trance (makes dodging and scoring hits much easier).
If it's not too much of a shameless self-insert, I offer you to take a look at my mod, particularly at the increased cost for armor and weapons and the skill boost for invaders. The former forces the player to be much more considerate with their units and resources. The latter makes it so the invaders quickly become more adjusted as they fight you - and may gain some hardened veterans to return next siege; additionally, there are more worldgen veterans who are actually skilled like ones.
Also, you might be interested in this method of boosting invaders by limiting their weapon and armor options to only include things that work well together: same method can be used to create invaders who only wear really protective armors.


So as far as I can tell from the existing research, this armour should at least be able to stop small steel darts. But in practice, that's not the case at all, which just does my head in.
Either something major has been overlooked, or I've fucked up something simple. Given both DF and myself, either is possible.

Hm. I suspect, the Area value is the most vague here, when it comes to armor. I don't actually think that the LAYER_SIZE value affects it, although, the wiki suggests otherwise. I also recall that the Area in question is always taken from the smallest value: in such a test, that would be the contact area of a blowdart, which equals 1.
Regardless, as far as my observations go, a material with higher shear values always reliably breaks a material with lower shear values - the only exception being really small velocities and/or really large contact areas on weapons, and even then the layer gets quickly broken after multiple hits.
« Last Edit: April 15, 2019, 02:28:42 pm by Sver »
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DF Combat Reworked
The force pulls neck, doing nothing! Also, armor matters, weapons are distinct, organs hurt and other stuff.

kiwiphoenix

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Re: Combat mechanics: thickness/mass?
« Reply #5 on: April 15, 2019, 04:01:32 pm »

The main handicap goblins suffer from when facing an average player's militia is not the items, though - it's the skill difference first and material difference second.
Yeah... perhaps didn't phrase it right, but that's exactly the point. The reason for my armour fixation is that most of the other major factors are pretty straightforward to tinker with. But when it comes to equipment, all the variables come together in an arcane mess that I cannot begin figure out. So designing things that interact in vaguely sane ways (eg believable weights, believable injuries, no real-world tool-grade metal able to effortlessly lightsabre through any other) just comes down to tweaking numbers and reloading the arena for hours at a time. As you already know, by the looks of things.

If it's not too much of a shameless self-insert...
Hahaha, with this much effort put in, reckon you've earned the right to a bit of self-promotion! Included a lot of little details that I never even thought of. Thanks, will definitely take a closer look...

So, I'm just starting to muck about with DF after a couple years away, while it looks like you've already learned your way around v0.44 modding. May I ask if you ever worked out a trick for getting new equipment to function as intended? Or does it just come down to reloading the arena until the insanity comes down to an acceptable level?

I don't actually think that the LAYER_SIZE value affects it...
Seems that way from my own tests, too. Even when the iron plate was bumped up past 30kg, that 80g steel dart was still tearing spleens left and right.
...in such a test, that would be the contact area of a blowdart, which equals 1.
Funnily enough, even a contact area of 1 would still leave 20.8 momentum threshold according to the wiki formulae.
...as far as my observations go, a material with higher shear values always reliably breaks a material with lower shear values...
Hm. Might just end up smoothing out the strength disparities between different metals, then. Was really hoping to avoid that, because it sounds like a bastard and a half to actually sit down and do, but if the alternative is Steel Über Alles...
« Last Edit: April 15, 2019, 04:03:41 pm by kiwiphoenix »
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Hetsin

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Re: Combat mechanics: thickness/mass?
« Reply #6 on: April 15, 2019, 04:16:31 pm »

Well, I noticed that your calculated momentum is a bit off, if the wiki is correct.

Quote
Ranged Weapon Momentum: M = (w_density*w_size)/10^5 * min(105*(SHOOT_FORCE/20)/(w_density*w_size), SHOOT_MAXVEL/10)

Bow and Crossbow Momentum: M = (w_density*150)/10^5 * min(10^5/(w_density*3), 20)
If 20 is smaller because the ammunition is density 1666 or less, M = w_density*3/100 = w_density*0.03
If 20 is larger because the ammunition is density 1667 or larger, M = 50

If your shoot force is 1 million and Max vel is 100, Max vel will always be the minimum. So your momentum is 7850*150/10^5*10=117.75. Since that's less then the cap of shoot force/20, then it's the final result, if I didn't mess up somewhere.
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kiwiphoenix

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Re: Combat mechanics: thickness/mass?
« Reply #7 on: April 16, 2019, 02:57:50 pm »

The attack momentum formula used is... written in v0.40, but it's probably still true in v0.44.
...or I've fucked up something simple...
...if the wiki is correct.
Bwahahahaha, well, bollocks. Looks like I was using an outdated formula.

If your shoot force is 1 million and Max vel is 100, Max vel will always be the minimum. So your momentum is 7850*150/10^5*10=117.75. Since that's less then the cap of shoot force/20, then it's the final result, if I didn't mess up somewhere.
Funny thing is, though, both the v0.40 formula and the (more complicated and so presumably more accurate) wiki one both happen to align when given size 10 vel 100 iron.
Looks like you plugged in a size 150, which is totally reasonable, since I never actually said otherwise.
In fact, you perfectly illustrated the confusion. Size 150 (M=117) should theoretically punch through while size 10 (M=8) is stopped, which would be perfect.

Did notic that if one plays with the inputs a bit, the results of the new and old formulae don't always line up - and are often separated by a factor of 10. Welp, that'll teach me to trawl old forum posts instead of just taking the wiki at face value, haha. Thanks for pointing that out!
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