I set out to find an explanation of the game mechanics behind "X is propelled away by the force of the blow!" and made some discoveries. Comments or additional information would be appreciated. I put this on the modding forum because the knockback mechanic is too weak to be practical for most fort/adventure players, but you guys might want to create knockback creatures and weapons.
1. Law of cartoon motionObjects in flight stay at the same elevation and velocity until they run out of momentum, at which point they fall straight down. This may change with soon-to-come updates (parabolic minecart paths).
2. Conservation of momentumRegardless of the source of the impulse, the distance a creature is propelled is related to its own weight. Most fleshy creatures have similar density, so we can use size instead of finding the weight. If a bronze colossus can kick a dwarf 2 tiles, it can kick a dog 4 tiles, a badger 8 tiles, or a albatross 15 tiles.
60000 x 2 = 30000 x 4 = 15000 x 8 = 8000 x 15 = 120000.
3. TerminologyMany players refer to units of distance or weight in the game as "Urists". Since momentum is mass x velocity, the units would be Urists^2/tick, which is a mouthful. From now on I am going to refer to these units as "Moruls", in honour of the Orc-golfing dwarf of forum legend. In the above example, the bronze colossus kick is 120000 moruls.
4. Minimum distance corollaryThe bronze colossus in the above example can't propel anything larger than size 120000 with a kick, since the distance would become less than 1 and the game appears to round distance down. This is true regardless of the source of the impulse.
5. Crossbow moddingIf you mod the [SHOOT_FORCE:1000] and [SHOOT_MAXVEL:1000] of a crossbow to 1000000 each, the impulse delivered to the target is around 350000 moruls (there is some random variation). This does scale linearly with changes to the force or maxvel, but is independant of the bolt weight. It appears that heavy bolts and light bolts have the same momentums when launched, but different velocities.
6. Maximum distance capAll forms of knockback/propelling are capped at a maximum distance of 50 tiles, except for the Throwing wrestling move which appears unlimited.
7. Throwing (wrestling move)Bronze colossuses can throw creatures at about 11000000 moruls, enough to throw a dwarf 183 tiles. Throwing appears to scale linearly with creature size, as a dwarf can throw a cat 6 tiles or a chicken 11 tiles (33000 = 11000000 * 20000000/60000). Throwing doesn't appear to change with the thrower's density or weight. Throwing doesn't scale with the size of your hands.
8. Chunky salsa ruleFollowing from step 7 experiments, the following effects were noted when a bronze colossus threw various creatures:
a) hippo-stunned but alive
b) saltwater crocodile-suffered falling damage "takes the full force of the impact"
c) cow-limb seperation instant death "slams into an obstacle and blows apart!"
Similar tests with a Troll throwing kea, chicken, cat, albatross, and badger suggest that if a creature is propelled a distance of 10 or less tiles, it is stunned but unharmed, whereas 11-20 tiles causes falling damage. If a creature was going to be tossed over 20 tiles distance, but a wall intervened, it will blow apart.
9. Punching/kickingPunching and kicking appears to scale linearly with the weight of the body part used as a weapon. If a creature can propel someone 21 tiles with a normal right hand, a left hand 10x smaller will propel them 2 tiles. The relationship between creature size and kick scaling is kind of strange and more research would be required. Ogres have a 3000 morul kicking power, 1/10 of what would be expected from linear scaling. Smaller creatures are untestably weak.
10. Strength and agilityStrength appears to scale propelling power from various sources both linearly with the strength value, but also linearly with any resulting changes in speed due to muscle mass. Propelling power doesn't scale directly with agility, but does scale with the resulting speed change. The double strength and double agility of vampires lead to a 1.8x increace in speed and 3.5x increase in propelling power in some subjects.
11. WeaponsWeapons really suck right now at propelling creatures. A bronze colossus can put out 6000 moruls with a platinum maul, or 2000 moruls with a platinum mace. Weapon knockback is linearly proportional to weapon weight and attack velocity. The weight of the weapon user doesn't scale the weapon's knockback. I couldn't find a relationship between weapon minsize and 2handedsize and knockback.
Weapon knockback scales very strangely with the size of the user, and more research would be required. In general, creatures over size 1000000 can knock things around with modestly boosted weapons or stats, whereas smaller creatures require ludicrous boosts to get any results.
Despite this, any creature holding a giant sperm whale corpse (301015 urists!) can hit other creatures with it for a 90000 morul knockback. Why a dwarf can throw a whale at a cat to knock it 18 tiles away, yet can only throw the cat itself 6 tiles, and can't even kick or hammer-golf the cat a single tile is beyond me.
12. Target body partIt appears that knockback only happens when a creature is struck in the upper body, lower body, or head.
13. ReferencesBronze colossus lower body & Platinum maul: Surprisingly bad weapons
http://www.bay12forums.com/smf/index.php?topic=105016.018 march 2012
Footkerchief's explanation
http://www.bay12forums.com/smf/index.php?topic=100687.msg3036876#msg303687626 feb 2012
also bug report
http://www.bay12games.com/dwarves/mantisbt/view.php?id=344Person Shredding Ammo
http://www.bay12forums.com/smf/index.php?topic=98930.012 jan 2012
Two-handed hammers, or "Teaching Goblins to Fly"
http://www.bay12forums.com/smf/index.php?topic=77912.020 feb 2011
Presenting: The Most Interesting Dwarf in the World
http://www.bay12forums.com/smf/index.php?topic=34933.msg591273#msg5912738 june 2009
Author
Topic: Knockdown (propelled by the blow!) SCIENCE (Read 8996 times)