Hit Feedback: Structure and Implementation

This chapter starts from design theory, breaks down hit feedback in action games by sensory dimension, and uses melee attacks as a complete case study for target acquisition, hit validation, and two-sided feedback presentation.

3.1 The Components of Hit Feedback in Action Games

Classification Method

I usually classify hit feedback by sensory dimension, breaking it into visual, auditory, haptic, and control dimensions.

Visual Dimension

Category	Concrete Methods
Character animation	Anticipation and silhouette before attack, attack trajectory and weapon trail, recovery and inertia after attack
Hit feedback	Hit Stop / hit pause / hit freeze, tuned based on weapon weight, sharpness, and impact force
Hit reaction	Hit displacement and hit stun through reaction animation
Visual effects	Contact-point VFX such as blood, sparks, and dust, usually emitted opposite the hit direction
Environmental interaction	Ground or grass disturbance
Screen effects	Full-screen vignette and post-processing effects
Camera	Camera shake, aligned with the attack direction and scaled by damage; dolly, zoom, or special camera shots

Auditory Dimension

Category	Concrete Methods
SFX layering	Swing layer, impact layer with material differentiation and stronger low frequency for heavy hits, and reverb layer for spatial echo
Dynamic feedback	Pitch variation and special handling for critical hits

Haptic and Control Dimension

Category	Concrete Methods
Controller vibration	Vibration hierarchy through intensity, directionality, and damping
Input and timing	Input buffering, which caches player input before the current action ends and chains into the next action by priority
Hit Stop	Hit Stop changes the rhythm of the player’s button input

3.2 Melee Attack Example: Target Acquisition, Hit Validation, and Presentation

3.2.1 Attack Startup and Target Capture

1. Trigger phase

   The player’s left mouse input (IA_LightAttack) activates the light attack Ability. The system starts the LightAttack ComboGraph and immediately executes the GetLightAttackTarget function to search for targets.

2. Broad-phase filtering

   A Sphere Overlap is executed around the character with radius x, collecting all Pawn Actors within range except the player. If no result is found, the function exits.

3. Fine-grained filtering (three-step filtering)

   Step	Content
   Tag check	Removes Actors that do not contain the Attackable Tag, filtering out allies and non-interactive objects. Remaining targets are added to the HitActors array.
   Distance validation	Removes targets farther than AttackAttachMinDist (the actual in-project name; semantically it represents the maximum effective attack-magnetism range).
   Best-target selection	Selects the Actor closest to the player as the final Target Actor.

Future Optimization — Weighted Target-Scoring System

Cost = (distance × W₁) + (angular deviation from camera center × W₂) + (stick direction deviation × W₃) + (enemy special state cost × W₄)

The target with the lowest cost becomes the final lock-on target. Alternatively, the terms can be normalized and inverted into positive scores before selecting the highest score.

3.2.2 Handling the OnHit Event

When ComboGraphCollision detects that the weapon detection volume overlaps an object, it broadcasts the On Hit Registered event and executes the following logic:

1. Target filtering

   The Hit Actor is extracted from the Hit Result and checked for the Attackable Tag. Only Actors with this Tag, namely enemies, continue into the subsequent logic. Otherwise, the flow terminates immediately.

2. Damage and event dispatch

   After the target is validated, the Report Damage Event function is called with the victim, instigator, and damage value.

3. GAS event payload construction

   Make GameplayEventData builds the event payload, and Ability Target Data from Hit Result converts the physical collision result into a data format GAS can consume.

4. Sending the Gameplay Event

   An event carrying the Event.Montage Tag is sent to the player itself (Self), notifying GAS that an attack has landed and triggering presentation-layer hit feedback.

5. Resource refill: mana gain on hit

   A GE Spec instance is created from GE_Mana_Regen. The Assign Tag Set by Caller Magnitude node dynamically sets the recovery value through the SetByCaller.Mana Tag. This avoids hard-coding the value inside the GE and allows different combo stages to tune the recovery amount independently.

6. UI update

   Show Mana UI is called so the UI can read the latest Attribute value and refresh the HUD mana bar.

3.2.3 Attribute and Tag Propagation After OnHit

After the character sends the Event.Montage Tag to itself, ComboGraph captures the event and executes the corresponding logic:

1. Activates GE_Damage_Melee (GameplayEffect), which internally activates GE_HitReaction_Melee and modifies the Health Attribute. The value is Set by Caller, namely -5.0 as configured in ComboGraph.
2. Activates GE_Cost_LightAttack to consume stamina for this attack stage.

GE_HitReaction_Melee grants the target Actor, the hit enemy, the Event.Character.BeingHit.Melee Tag, which activates that Actor’s hit-reaction GameplayAbility.

Benefits of This Design

• Dynamic damage: through SetByCaller, one GE instance can handle dynamic damage values, making later tuning easier.
• Attacker/victim decoupling: hit reactions are triggered through Tags, following dependency inversion. The victim’s own GAS logic determines how it responds, allowing different monsters to implement polymorphic reactions.
• Low coupling: damage, cost, and state validation are separated, making future Buff extensions easier.

3.2.4 Player-Side Hit Feedback Implementation

After the player character receives the Event.Montage signal, it executes GameplayCues to present player-side hit feedback:

GameplayCue	Effect
Blood splash VFX	Blood VFX at the impact point
Spark VFX	Weapon collision sparks
Impact-point feedback VFX	Visual feedback at the Impact Point
Hit SFX	Character-side audio feedback for a landed hit

Note

In ComboGraph, different player-side feedback can be configured visually for each attack animation.

3.2.5 Enemy-Side Hit Feedback Implementation

After the target character receives the Event.Character.BeingHit.Melee signal, it executes GA_HitReaction_Enemy_Melee, which is triggered by the specified Tag.

The current GA contains the following hit feedback elements:

Effect	Description
Camera shake	Camera Shake
SFX playback	Hit reaction sound
Slow motion	Brief time dilation
Hit Stop	Frame freeze to emphasize impact force
Hit reaction animation	Hit stun and displacement