Resistance

Based on game build 714014 | Last updated: 2026-03-03

Overview

The Resistance component enables an entity to declare resistance (typically immunity) to damage from entities or weapons carrying specific tags. It is commonly used to implement mechanics such as fireproofing (resistsfire), electric resistance, or boss immunities to certain weapon types. This component does not reduce damage values directly; instead, it flags resistance conditions and triggers events when damage is resisted.

Usage example

local inst = CreateEntity()
inst:AddComponent("resistance")

-- Grant resistance to fire-tagged attackers
inst.components.resistance:AddResistance("fire")

-- Grant resistance to weapons with the "electric" tag
inst.components.resistance:AddResistance("electric")

-- Optionally configure custom logic
inst.components.resistance:SetShouldResistFn(function(ent) return ent.components.health and ent.components.health:IsAlive() end)
inst.components.resistance:SetOnResistDamageFn(function(inst, damage, attacker)
    -- e.g., play sound, spawn FX
end)

Dependencies & tags

Components used: None identified
Tags: Adds and removes custom string tags (e.g., "fire", "electric"). No built-in tags are managed internally.

Properties

Property	Type	Default Value	Description
tags	table	{}	Map of resistance tags; keys and values are identical tag strings.
onresistdamage	function or nil	nil	Optional callback invoked when damage is resisted. Signature: fn(inst, damage_amount, attacker).
shouldresistfn	function or nil	nil	Optional predicate function that determines whether resistance should apply. Signature: fn(inst) -> boolean.

Main functions

AddResistance(tag)

• Description: Registers a tag as a source of damage that this entity resists.
• Parameters: tag (string) — the tag to resist (e.g., "fire", "boss").
• Returns: Nothing.

RemoveResistance(tag)

• Description: Removes a previously registered resistance tag.
• Parameters: tag (string) — the tag to remove from resistance.
• Returns: Nothing.

HasResistance(attacker, weapon)

• Description: Checks if the entity resists damage from the given attacker and/or weapon by comparing their tags against registered resistances.
• Parameters:
  • attacker (GO or nil) — the entity delivering the damage.
  • weapon (GO or nil) — the weapon used to deal damage (may be nil).
• Returns: true if any tag on attacker or weapon matches a registered resistance; otherwise false.
• Error states: Returns nil implicitly if no matching tag is found or if attacker is nil.

HasResistanceToTag(tag)

• Description: Checks if a specific tag is currently a registered resistance.
• Parameters: tag (string) — the tag to check.
• Returns: true if the tag is registered; otherwise false.

SetOnResistDamageFn(fn)

• Description: Sets the callback function executed when damage is successfully resisted.
• Parameters: fn (function or nil) — function to invoke with (inst, damage_amount, attacker). Pass nil to clear.
• Returns: Nothing.

SetShouldResistFn(fn)

• Description: Sets a predicate function that controls whether resistance should be applied in a given scenario (e.g., based on health state).
• Parameters: fn (function or nil) — function to invoke with (inst) and returning true/false. Pass nil to enable resistance unconditionally.
• Returns: Nothing.

ShouldResistDamage()

• Description: Evaluates the shouldresistfn to determine if resistance should currently be active.
• Parameters: None.
• Returns: true if shouldresistfn is nil or returns true; otherwise false.

ResistDamage(damage_amount, attacker)

• Description: Triggers the resistance action. Calls onresistdamage and fires the damageresisted event.
• Parameters:
  • damage_amount (number) — the amount of damage being resisted.
  • attacker (GO) — the entity responsible for the damage.
• Returns: Nothing.

GetDebugString()

• Description: Returns a human-readable string listing all registered resistance tags for debugging.
• Parameters: None.
• Returns: string — e.g., "Resists: fire, electric".

Events & listeners

• Pushes: damageresisted — fired when ResistDamage is called. Data payload: {damage_amount = number, attacker = GO}.