So, if we go back to Dwarf Fortress for a bit...
What aspects of this complex discussion would need to be addressed in the game, and in what ways?
It's probably still possible to simplify the different factors into a few numbers and formulas that would make the simulation reasonably realistic, while still remaining comprehensible.
Here are some suggestions:
Global impulse, transferred by the contact between weapon and target.
This is on the largest scale, counting the entire duration of impact and the whole area of contact. No armor can counter the global impulse itself. However, a large mass dilutes the effects of impulse. A high global impulse can knock a target off his feet or send him flying, or give him damage just from being jostled inside his armor. Global impulse is simply the velocity times mass of the weapon (or a direct function of the strength of the user, and the effective length of the swing - which in turn is a function of the weapon)
works like global impulse, except it is regarded on the level of a body part
- basically a rigid body attached to the rest of the body by joints and muscles, and in particular covered by armor that is not rigidly connected to the armor of the rest of the body. Local impulse causes strain on the joints and muscles connecting the body part and may dislocate it or even tear it off. It also causes jostling of the body part (concussion or other internal damage). The only way armor can affect all this is by helping to keep limbs from being torn off. The jostling can be negated if the person is strong enough to hold the body part firm against the impulse.
is the impulse per surface area affected by the impact.
Here's where edged, pointed and blunt trauma differ. Armor serves largely to make this quantity smaller on the inside than the outside - spreading the impulse over a larger area. A sharp impact on a hard helm, padded on the inside, spreads the impulse over a large part of the skull - and the only damage suffered is from the local impulse (above). The point impulse on the outside of the armor is given by the weapon (blunt, spiked, pointy, edged, flanged), and this in turn determines whether the armor is damaged and/or penetrated. If it isn't penetrated, it spreads the impulse over a larger area on the inside: rigid armor extremely well, padded armor less so (allowing for bruises). If it is penetrated the area is the same, though some of the impact energy may be absorbed by the armor as it's damaged.
Sharpness has no effect on point impulse - even if the edge is ten times thinner on the microscopic scale, any armor (or skin) yields on impact enough to negate this, without necessarily sustaining any damage. Sharpness is about the microscopic jagged structures that tear at the material as they're passed over it. Sharpness merely lessens the threshold point impulse needed to penetrate armor or skin.
Damage properties of weapons:
Heft: A measure of weight and length combined, measuring how much power can be put into a stroke with this weapon. Could be a range, where a given weapon allows different swings. You need strength commensurate with the heft to use the weapon effectively.
Pointedness: How well the weapon concentrates force into a point or line. Low for blunt weapons, intermediate for swords (when slashing) and flanged maces, high for daggers, arrows and swords (when thrusting).
Sharpness: How sharp the edge/point is on a microscopic level.
Material properties of weapons/armor:
Hardness: How well a weapon holds an edge. How sharp it can be, and how fast it loses the sharpness when cutting. How well an armor stands up to cutting edges.
Toughness: Resistance to impulse(/force). How well a weapon stands up to parrying heavy blows without bending or breaking. How much point force an armor stands up to before denting.
Tensile strength: Resistance to being pulled apart.
Density: What it sounds like. Determines how thick a usable armor can be. Determines how light a usable sword can be. (Getting a weapon heavy enough is less of a problem)
(These are not quite realistic properties - an object can be fragile because it's too soft, or because it's too hard - but I think they're close enough to cover most cases and also allow for mythical materials)
The impulse (all three types) transferred between weapon and target will be lessened if the hit is oblique, and/or the target rolls with it. Punching a mosquito in flight does little good. Deflection can result from a poor hit, a nearly-successful parry, cleverly made armor or any combination, as well as the target being too small and light to absorb the hit properly.
So, a hit would be processed something like this:
Force of impact = heft - deflection
Outside point impulse = force of impact / weapon pointedness
Penetration = outside point impulse - armor toughness + max(sharpness - armor hardness, 0)
If no penetration:
Inside point impulse = force of impact / armor paddedness
Tissue damage = [probably a function of penetration and sharpness, as well as weapon type; out of scope for this thread though]
Jostle factor = (Force of impact - limb strength) / limb weight [including armor weight]
Global impulse = Force of impact / total mass of target
Oh, and if your armor menaces with spikes of obsidian, attackers may as well have the above applied in reverse...
The above deals with slashing, blunt and piercing damage, that is when the damage comes from a single instantaneous impact. Examples:
Fall onto a stone floor: Large impact force, very low pointedness, 0 sharpness. Damage mostly from jostling (concussion, damages to joints and spine) and blunt at the point of impact, unless wearing hard armor there
Sword slash to chain-mailed torso: Medium impact force, medium pointedness, high sharpness. Armor has high hardness. Let's say there's no penetration. Result: Same local impulse comes through, but blunt, and spread over a larger area. Probably bruises
Sword thrust to chain-mailed torso: Medium impact force, high pointedness, high sharpness. Some penetration; armor padding factor ineffectual. Sharpness applied to the body (ow).
Wooden club to aluminum helmet: Medium impact force, low pointedness, 0 sharpness. No penetration, padding effectively negates inside point impulse. Jostle factor: High, because head+helmet mass is low. Light concussion.
Apart from single-impact damage types, there are opposed-force damage types:
Crushing damage: A body part stuck between two other objects. Door closes on foot. Drawbridge descends on head. Colossus flattens against wall. In these cases, there's no deflection, no jostling. Armor toughness only applies if the armor is rigid all around.
Shearing damage: Body part caught between two more or less sharp objects. Giant cave lobster got your leg. Goblin combat scissors. Like crushing, except some sharpness applies.
Tearing damage: Something pulling two body parts in different direction. Wrestling. Picked up by head by giant eagle. Applies like local impulse; armor only helps in weakest-link manner (plate mail treated as its backing). Tensile strength used.
Rending damage: Something sharp's been forced into you or your armor, and is now being tugged violently. Bear claws. Dragged across spikes after spectral chariot. Normal rules to penetrate in the first place, tensile strength applied to see if armor rips open.
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Topic: Blunt weapons should ignore armour (Read 11043 times)