Melee integration

USDFMeleeHitSenderComponent is an optional bridge between a melee contact your game already detected and an SDF destructible. It detects nothing itself.

Setup

1. Add SDF Melee Hit Sender to the Actor that swings — usually the character, sometimes the weapon Actor.
2. Configure HitSettings.
3. Call Begin SDF Melee Swing when the damage window opens.
4. Call Send SDF Melee Hit for each contact your trace detects.
5. Call End SDF Melee Swing when the window closes.

No timer and no tick are used. The swing window is explicit state.

Hit settings

FSDFMeleeHitSettings:

Property	Default	Meaning
Damage	25.0	Conventional damage written into the payload
DestructionPower	Light	Capability gate of the swing
ImpulseStrength	500.0	Impulse magnitude written into the payload
DamageType	none	Optional engine damage type
GameplayTags	empty	Tags carried through to listeners
bRequireActiveSwing	true	Delivery is allowed only between Begin and End
bSuppressRepeatedActorsPerSwing	true	One Actor receives at most one hit per swing

Different attacks need different values: set HitSettings from your attack data just before Begin SDF Melee Swing, or use several sender components.

The swing concept

Begin Swing   -> opens the window, clears per-target history, returns a stable swing id
Submit Contact -> Send SDF Melee Hit, once per detected contact
              -> at most one delivery per Actor for this swing
End Swing     -> closes the window
Next swing    -> history is reset again

Begin SDF Melee Swing accepts an optional requested id and returns the active swing id. Is Melee Swing Active and Get Active Swing Id expose the current state.

This matters because a multi-trace weapon typically reports the same crate three or four times in one animation. Without suppression, a crate with 100 health would take 75 damage instead of 25 from a single swing.

Sending a contact

Send SDF Melee Hit takes:

Parameter	Notes
TargetActor	Optional when HitResult already contains an Actor
HitResult	Your trace or overlap result; supplies impact point and normal
AttackDirection	Points from the attacker toward the target
InstigatorController	Controller credited with the hit
DamageCauser	Usually the character or the weapon Actor
Weapon	Any UObject; SDF does not interpret it
RandomSeed	-1 to generate one

It returns FSDFMeleeDeliveryResult:

Field	Meaning
bDelivered	The hit reached a destructible
bSuppressedAsDuplicate	Same Actor, same swing
bRejectedBecauseSwingInactive	No swing window was open
bTargetSupportsDestruction	The target implements the destructible contract
Target	The Actor that was addressed
SentHit	The exact payload that was built
DestructionResult	The target’s own evaluation

Non-destructible targets

Hitting a wall, an enemy or anything that does not implement the destructible contract is safe: the result reports bTargetSupportsDestruction = false and nothing else happens. You do not need to filter your traces before calling.

Blueprint example

Inside your character Blueprint:

AnimNotify: DamageWindowStart
    -> SDF Melee Hit Sender -> Begin SDF Melee Swing

Weapon trace produced a Hit Result
    -> SDF Melee Hit Sender -> Send SDF Melee Hit
         Target Actor        = Hit Result -> Hit Actor
         Hit Result          = Hit Result
         Attack Direction    = normalize(Target Location - Attacker Location)
         Instigator          = Get Controller
         Damage Causer       = self
         Weapon              = EquippedWeapon
         Random Seed         = -1
    -> break the returned result to log or react

AnimNotify: DamageWindowEnd
    -> SDF Melee Hit Sender -> End SDF Melee Swing

C++ example

// Damage window opens
MeleeSender->BeginMeleeSwing();

// For each detected contact
const FVector AttackDirection =
    (HitResult.GetActor()->GetActorLocation() - GetActorLocation()).GetSafeNormal();

const FSDFMeleeDeliveryResult Delivery = MeleeSender->SendMeleeHit(
    HitResult.GetActor(),
    HitResult,
    AttackDirection,
    GetController(),
    this,
    EquippedWeapon,
    /* RandomSeed */ -1);

if (Delivery.DestructionResult.bDestructionTriggered)
{
    // React: hit stop, camera shake, resource award...
}

// Damage window closes
MeleeSender->EndMeleeSwing();

Listening to deliveries

OnMeleeHitDelivered broadcasts the full FSDFMeleeDeliveryResult for every call, which is a convenient single place to drive hit stop, controller rumble or combat log entries without wiring them at every call site.

Common mistakes

Symptom	Cause
Nothing breaks, bRejectedBecauseSwingInactive is true	Begin SDF Melee Swing was never called, or End fired too early
One swing removes several times the expected damage	bSuppressRepeatedActorsPerSwing was disabled
Debris flies toward the attacker	AttackDirection is reversed
Delivered but Outcome is Rejected	The swing’s DestructionPower is below the profile’s MinimumDestructionPower