68 lines
2.7 KiB
Lua
68 lines
2.7 KiB
Lua
-- Elemental damage typing. Every hit that lands - melee, a bolt, a thrown
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-- weapon, a hazard tick, a status effect's damage-over-time - is tagged with
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-- one of the types below, and this module decides how much of it actually
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-- gets through. A defender's tier for a type comes from up to two places: its
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-- own base profile (bestiary data, e.g. a dragon's own hide) and whatever it
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-- has equipped (weapon/armor/ring/bow, e.g. a ring of cold resistance). The
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-- single best (most protective) tier across those sources wins - immune beats
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-- resist beats weak beats the normal default - so a found ring can cancel out
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-- an innate vulnerability, but nothing ever stacks two resists into a second
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-- discount or two weaknesses into a bigger penalty.
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local Resistances = {}
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Resistances.PHYSICAL = "physical"
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Resistances.FIRE = "fire"
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Resistances.COLD = "cold"
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Resistances.POISON = "poison"
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Resistances.LIGHTNING = "lightning"
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Resistances.ARCANE = "arcane"
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Resistances.TYPES = {
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Resistances.PHYSICAL, Resistances.FIRE, Resistances.COLD,
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Resistances.POISON, Resistances.LIGHTNING, Resistances.ARCANE,
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}
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Resistances.IMMUNE = "immune"
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Resistances.RESIST = "resist"
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Resistances.WEAK = "weak"
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Resistances.NORMAL = "normal"
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local RANK = { immune = 3, resist = 2, weak = 1, normal = 0 }
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-- Slots checked alongside an entity's own `resist` table, in a fixed order so
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-- the result never depends on Lua's unspecified pairs() iteration order.
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local EQUIP_SLOTS = { "weapon", "armor", "ring", "bow" }
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local function tierFrom(source, damageType)
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return source and source.resist and source.resist[damageType]
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end
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-- The single tier that governs `damageType` incoming against `entity`, folding
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-- in its own base profile and every equipped slot that carries one.
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function Resistances.tierOf(entity, damageType)
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local best = tierFrom(entity, damageType) or Resistances.NORMAL
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for _, slot in ipairs(EQUIP_SLOTS) do
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local tier = tierFrom(entity[slot], damageType)
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if tier and RANK[tier] > RANK[best] then
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best = tier
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end
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end
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return best
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end
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-- Scales a already-computed `amount` of `damageType` damage by `entity`'s
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-- tier for that type. Immune drops it to nothing outright rather than merely
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-- halving it, so it can floor damage below the "always at least 1" guarantee
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-- combat.lua's own minimum otherwise enforces.
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function Resistances.apply(entity, amount, damageType)
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if amount <= 0 then return amount end
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local tier = Resistances.tierOf(entity, damageType or Resistances.PHYSICAL)
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if tier == Resistances.IMMUNE then return 0 end
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if tier == Resistances.RESIST then return math.floor(amount / 2) end
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if tier == Resistances.WEAK then return math.floor(amount * 1.5) end
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return amount
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end
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return Resistances
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