124 lines
4.1 KiB
Lua
124 lines
4.1 KiB
Lua
-- Carry weight. Every item kind has a physical weight (gear scales a little
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-- with its power, the way a heavier blade hits harder); a carrier's capacity
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-- grows with level, the same knob progression.lua turns for hp. Exceeding
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-- capacity does not block a pickup outright - it slows the carrier down
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-- instead (see Entity:effectiveSpeed), and a wide overage on top of that also
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-- costs defense, the same shape a status.lua debuff takes (see
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-- Entity:effectiveDefense). Nothing here is persisted: weight is entirely a
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-- function of entity.inventory and entity.level, both already serialized, so
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-- a save/load round trip recomputes the identical tier for free.
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--
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-- Monsters are never excluded from these checks (there is no species flag to
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-- opt out), but their inventory is always empty in practice - abilities.lua
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-- and combat.lua never stash loot on a monster - so in play this only ever
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-- matters for the player.
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local Items = require("items")
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local Encumbrance = {}
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Encumbrance.BASE_CAPACITY = 12
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Encumbrance.CAPACITY_PER_LEVEL = 4
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Encumbrance.BURDENED_MULT = 1.5
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Encumbrance.LIGHT = "light"
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Encumbrance.BURDENED = "burdened"
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Encumbrance.OVERLOADED = "overloaded"
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Encumbrance.BURDENED_SPEED_PENALTY = -20
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Encumbrance.OVERLOADED_SPEED_PENALTY = -45
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Encumbrance.OVERLOADED_DEFENSE_PENALTY = -2
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-- Base weight per item kind, before any power-scaling below. Kinds absent
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-- here (gold, keys) default to a flat 1 rather than 0: even a featherweight
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-- trinket takes up some of the pack, and a strictly-zero-weight kind would
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-- let a hoard of them carry for free.
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local BASE_WEIGHT = {
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[Items.POTION] = 2,
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[Items.SCROLL] = 1,
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[Items.WEAPON] = 6,
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[Items.ARMOR] = 9,
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[Items.RING] = 1,
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[Items.FOOD] = 3,
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[Items.KEY] = 1,
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[Items.TOME] = 4,
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[Items.AMULET] = 2,
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[Items.BOW] = 7,
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[Items.AMMO] = 1,
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[Items.GOLD] = 0,
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[Items.GEM] = 1,
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[Items.CHARM] = 2,
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[Items.KIT] = 3,
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[Items.HERB] = 1,
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[Items.CONTRACT] = 1,
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}
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-- Kinds whose power rating (a straightforward proxy for how much metal went
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-- into them) adds a little extra weight on top of the flat base.
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local POWER_SCALES = {
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[Items.WEAPON] = true,
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[Items.ARMOR] = true,
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[Items.BOW] = true,
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}
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-- Kinds that stack into one inventory slot via a `count`/`amount` field, so
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-- their weight must scale with the stack rather than being charged once.
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local STACK_FIELD = {
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[Items.AMMO] = "count",
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[Items.GOLD] = "amount",
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}
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function Encumbrance.itemWeight(item)
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local weight = BASE_WEIGHT[item.kind] or 1
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if POWER_SCALES[item.kind] then
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weight = weight + (item.power or 0) // 3
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end
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local stackField = STACK_FIELD[item.kind]
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if stackField then
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weight = weight * (item[stackField] or 1)
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end
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return weight
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end
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-- Loose inventory plus whatever is currently worn or wielded: a sword on
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-- your belt weighs exactly as much as one in your pack.
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function Encumbrance.carriedWeight(entity)
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local total = 0
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for _, item in ipairs(entity.inventory) do
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total = total + Encumbrance.itemWeight(item)
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end
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for _, slot in ipairs({ "weapon", "armor", "ring", "bow" }) do
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local equipped = entity[slot]
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if equipped then total = total + Encumbrance.itemWeight(equipped) end
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end
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return total
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end
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function Encumbrance.capacityFor(entity)
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return Encumbrance.BASE_CAPACITY + (entity.level or 1) * Encumbrance.CAPACITY_PER_LEVEL
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end
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function Encumbrance.tierFor(entity)
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local carried = Encumbrance.carriedWeight(entity)
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local capacity = Encumbrance.capacityFor(entity)
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if carried <= capacity then return Encumbrance.LIGHT end
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if carried <= capacity * Encumbrance.BURDENED_MULT then return Encumbrance.BURDENED end
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return Encumbrance.OVERLOADED
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end
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function Encumbrance.speedPenalty(entity)
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local tier = Encumbrance.tierFor(entity)
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if tier == Encumbrance.BURDENED then return Encumbrance.BURDENED_SPEED_PENALTY end
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if tier == Encumbrance.OVERLOADED then return Encumbrance.OVERLOADED_SPEED_PENALTY end
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return 0
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end
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function Encumbrance.defensePenalty(entity)
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if Encumbrance.tierFor(entity) == Encumbrance.OVERLOADED then
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return Encumbrance.OVERLOADED_DEFENSE_PENALTY
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end
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return 0
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end
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return Encumbrance
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