Core Concepts

This page explains how ElysImpact’s pipeline works end-to-end, from calling PlayResponse to each handler completing.

The Pipeline

PlayResponse(Asset, Context)
       │
       ▼
UERP_ImpactSubsystem::CreateSession
       │
       ├─ Channel filter (muted? → drop)
       ├─ Feel Profile suppression check
       ├─ Combined intensity computation
       │     ContextOverride × AssetMultiplier × GlobalScale × ChannelScale × DI curve
       ├─ Choreography role assignment
       ├─ Dramatic Intensity accumulation
       │
       ▼
UERP_ImpactSession::Start
       │
       └─ For each Handler (concurrent):
             ├─ Pre-conditions (enabled? ExecutionChance? distance? tags?)
             ├─ StartDelay timer
             └─ Handler::Play_Internal

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Response Assets

UERP_ImpactResponseAsset is a UDataAsset. Open it in the editor to configure:

Property	Description
Handlers	List of inline handlers (EditInlineNew — configured directly in the asset)
IntensityMultiplier	Scales the combined intensity for all handlers in this asset
Channels	GameplayTag set — used for muting and per-channel intensity
DramaticContribution	How much this response contributes to the target’s DI accumulator
ChoreographyGroup	Tag-based area-response role system (see Choreography below)

Creating a Response Asset

1. Content Browser → right-click → Miscellaneous → Data Asset → UERP_ImpactResponseAsset
2. Add handlers via the + button in the Handlers array
3. Expand each handler to configure its properties

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Handlers

A handler is an EditInlineNew UObject that performs exactly one effect. Handlers run concurrently within a session — a Camera Shake and a Sound Effect in the same asset both start at the same time (subject to their individual StartDelay).

Common Handler Properties

All handlers share these base properties (on the UERP_ImpactHandler base class):

Property	Description
bEnabled	Toggle without removing the handler
ExecutionChance	Probability [0..1] that this handler fires on any given play
StartDelay	Seconds to wait before playing (within the session)
IntensityScale	Per-handler intensity multiplier
IntensityRandomRange	Adds random [-Range, +Range] to final intensity
IntensityOverLifetime	Optional curve: scales intensity over the handler’s duration
MaxPlayDistance	Beyond this distance from the camera, the handler is silenced
LODDistanceFade	Distance at which intensity starts fading
TargetTagRequirement	Handler only fires if target has these GameplayTags
SourceTagRequirement	Handler only fires if source has these GameplayTags
bQuantizeToBeat	Defers play to the next ElysMusicEngine beat division
BeatDivision	Which beat division to quantize to

Session Isolation

When a session is created, each handler template from the asset is duplicated (DuplicateObject) so concurrent sessions never share mutable state. You can play the same asset on 10 actors simultaneously — each gets its own handler instances.

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Intensity

The final intensity passed to each handler is:

CombinedIntensity = Context.IntensityOverride
                  × Asset.IntensityMultiplier
                  × Subsystem.GlobalIntensity
                  × ChannelIntensity (lowest among asset’s channels)
                  × DICurve(NormalizedDI)
                  × FeelProfile.GlobalIntensityScale

After choreography role assignment:

• Secondary role: × ChoreographyGroup.SecondaryIntensityScale
• Tertiary role: × ChoreographyGroup.TertiaryIntensityScale

Each handler then applies its own IntensityScale and curve on top.

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Impact Context

FERP_ImpactContext carries rich event data through the pipeline:

Field	Type	Description
Target	TWeakObjectPtr<AActor>	Actor receiving the response (required)
Source	TWeakObjectPtr<AActor>	Actor triggering the response (optional)
Instigator	TWeakObjectPtr<AController>	Controller responsible (optional)
EventTag	FGameplayTag	Semantic label (e.g., Impact.Hit.Heavy)
Magnitude	float	Raw value (damage, force…) — affects DI accumulation
ImpactPoint	FVector	World position of the impact
ImpactNormal	FVector	Surface normal at impact
IntensityOverride	float	Per-call intensity multiplier (default 1.0)
bSkipReplication	bool	If true, skip network propagation

Build a context manually or use the helper functions:

// Minimal
FERP_ImpactContext Context = UERP_ImpactStatics::MakeImpactContext(TargetActor, 1.f);

// From a hit result
FERP_ImpactContext Context = UERP_ImpactStatics::MakeImpactContextFromHit(HitResult, Damage);

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Dramatic Intensity

The DI system makes repeated responses feel progressively more impactful:

1. Each PlayResponse call accumulates DI on the target actor: CurrentDI += Magnitude × Asset.DramaticContribution
2. DI decays over time (exponential decay driven by DecayRate)
3. Normalized DI [0..1] is fed through the Feel Profile’s DramaticIntensityCurve
4. The curve output multiplies the combined intensity

Default behavior (no Feel Profile): linear scale from 1× at DI=0 to 2× at DI=1.

Read and reset DI from Blueprint:

Get Dramatic Intensity → (WorldContext, Actor) → float [0..1]
Reset Dramatic Intensity → (WorldContext, Actor)

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Choreography

When many actors are hit simultaneously, Choreography prevents visual overload by assigning roles:

• Primary: Full intensity — the most important response (usually the player’s target)
• Secondary: Reduced intensity (SecondaryIntensityScale, default 0.6)
• Tertiary: Minimal intensity (TertiaryIntensityScale, default 0.3)

Configure on the Response Asset’s ChoreographyGroup:

Property	Description
GroupTag	Unique tag identifying this choreography group
PrimaryLockDuration	Seconds before another actor can claim the Primary role
MaxSecondaryCount	Max concurrent Secondary responses
SecondaryIntensityScale	Intensity multiplier for Secondary
TertiaryIntensityScale	Intensity multiplier for Tertiary

Set the same GroupTag on all response assets that should compete for roles within an area.

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Sessions

A UERP_ImpactSession is a UObject that:

• Owns the duplicated handler instances
• Tracks handler completion
• Fires OnComplete when all handlers finish
• Is removed from ActiveSessions on the next subsystem tick

Sessions are GC-managed — they live as long as the subsystem holds a reference. You rarely need to interact with sessions directly.

To stop a session early:

UERP_ImpactStatics::StopSession(this, Session);
UERP_ImpactStatics::StopAllOnActor(this, TargetActor);

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Next Steps

Browse Handler Reference for all available effects.

Configure intensity scaling in Feel Profiles.

Organize your responses with Channels.