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AnimNotify

Version Info

Added in v1.17.0

Use AnimNotify to control KawaiiPhysics external forces and Alpha during animations.

Overview​

KawaiiPhysics v1.21 and earlier provide these three types of AnimNotify:

ClassTypePurpose
UAnimNotify_KawaiiPhysicsAddExternalForceNotifyAdd force instantly
UAnimNotifyState_KawaiiPhysicsAddExternalForceNotifyStateApply force during interval
UAnimNotifyState_KawaiiPhysicsSetAlphaNotifyStateOverride Alpha during interval

The three types above are available in v1.21 and earlier. Additional multiplier and gust Notifies are covered in the planned-v1.22 section below.

View Source

AnimNotify vs AnimNotifyState​

  • AnimNotify: Triggers on a single frame. Use for instant impacts
  • AnimNotifyState: Operates during start-to-end interval. Use for continuous effects

AnimNotifyState External Force

External force application via AnimNotifyState

AnimNotify_KawaiiPhysicsAddExternalForce​

AnimNotify that adds external force instantly.

Parameters​

ParameterTypeCategoryDescription
AdditionalExternalForcesTArray<FInstancedStruct>ExternalForceArray of forces to add
FilterTagsFGameplayTagContainerExternalForceTags to filter application targets
bFilterExactMatchboolExternalForceWhether to filter by exact tag match

Use Cases​

  • Impact on jump landing
  • Recoil on attack hit
  • Instant wind or explosion

Setup Steps​

  1. Open Animation Sequence
  2. Right-click on Notifies track → Add Notify → KawaiiPhysics Add External Force
  3. Add force presets to AdditionalExternalForces
  4. Configure FilterTags as needed

AnimNotifyState_KawaiiPhysicsAddExternalForce​

AnimNotifyState that applies external force during the interval. Adds force at notify start and automatically removes it at end.

Parameters​

ParameterTypeCategoryDescription
AdditionalExternalForcesTArray<FInstancedStruct>ExternalForceArray of forces to add
FilterTagsFGameplayTagContainerExternalForceTags to filter application targets
bFilterExactMatchboolExternalForceWhether to filter by exact tag match

Use Cases​

  • Hair flowing during dash
  • Special effects during skill activation
  • Continuous environmental forces

Setup Steps​

  1. Open Animation Sequence
  2. Right-click on Notifies track → Add Notify State → KawaiiPhysics Add External Force
  3. Drag to set application interval
  4. Add force presets to AdditionalExternalForces

AnimNotifyState_KawaiiPhysicsSetAlpha​

AnimNotifyState that overrides KawaiiPhysics node's Alpha during the interval. Adjust KawaiiPhysics intensity using animation curve values.

Parameters​

Alpha Settings​

ParameterTypeCategoryDefaultDescription
SourceEKawaiiPhysicsSetAlphaSourceAlphaCurveAlpha source type
CurveNameFNameAlpha-Curve name when Source=Curve
DefaultAlphaIfNoCurvefloatAlpha1.0Fallback value when curve unavailable (0.0-1.0)
ConstantAlphafloatAlpha1.0Constant value when Source=Constant (0.0-1.0)

Filter Settings​

ParameterTypeCategoryDefaultDescription
FilterTagsFGameplayTagContainerFilter-Filter target nodes by tags
bFilterExactMatchboolFilterfalseWhether to filter by exact tag match

Alpha Source (EKawaiiPhysicsSetAlphaSource)​

ValueDescription
CurveUse animation float curve
ConstantUse constant value

Use Cases​

  • Reduce physics during specific motions
  • Vary physics influence with animation
  • Physics control during cutscenes

Using Curves​

  1. Add a float curve to Animation Sequence
  2. Set curve name (e.g., KawaiiPhysicsAlpha)
  3. Set the same name in AnimNotifyState's CurveName
  4. Control Alpha value (0.0-1.0) with the curve
// Curve example
Time 0.0: Alpha = 1.0 (full physics)
Time 0.5: Alpha = 0.0 (physics off)
Time 1.0: Alpha = 1.0 (full physics)
Warning When CurveName Is Not Set

If Source = Curve but CurveName is left unset (None), a warning is shown in the Message Log (Asset Check) during editor asset validation (e.g., when saving or loading the Animation Sequence).

AnimNotifyState(KawaiiPhysics_SetAlpha) CurveName is empty in <asset path>

Always set CurveName when using curve-based control. Note that if CurveName is set but the curve value cannot be retrieved (e.g., the animation does not contain a curve with that name), no warning is shown and DefaultAlphaIfNoCurve is used instead.

Using Constant Value​

// Set physics to 50% during interval
Source = EKawaiiPhysicsSetAlphaSource::Constant;
ConstantAlpha = 0.5f;

GameplayTag Filtering​

The external-force and Alpha Notifies above support node filtering by GameplayTag. The planned-v1.22 Trigger Gust uses different tags for Nodes and Shared Publisher targets.

Setup​

  1. Set KawaiiPhysicsTag on KawaiiPhysics node
// In Animation Blueprint's KawaiiPhysics node
KawaiiPhysicsTag = FGameplayTag::RequestGameplayTag("KawaiiPhysics.Hair");
  1. Set target tags in AnimNotify's FilterTags
  2. Specify match condition with bFilterExactMatch

Filter Behavior​

bFilterExactMatchBehavior
falseMatches specified tag and its children (parent tags also allowed)
trueExact match only

Example: Distinguishing Multiple KawaiiPhysics Nodes​

// GameplayTag hierarchy
KawaiiPhysics
├── Hair
│   ├── Front
│   └── Back
├── Skirt
└── Cape
// Apply force to Hair only
FilterTags.AddTag("KawaiiPhysics.Hair");
bFilterExactMatch = false; // Hair.Front, Hair.Back also targeted

// Apply force to Hair.Front only
FilterTags.AddTag("KawaiiPhysics.Hair.Front");
bFilterExactMatch = true; // Exact match only

Best Practices​

1. NotifyState Interval Settings​

  • Align start/end with natural animation breaks
  • Use Alpha curve near start/end to avoid abrupt changes

2. Performance Considerations​

  • Avoid triggering many AnimNotifies simultaneously
  • Keep complex force calculations minimal

3. Debugging​

  • Set bDrawDebug = true on force presets to visualize vectors
  • Verify behavior in Animation Editor preview

Settings Multiplier / Trigger Gust (planned for v1.22)​

Not officially released

This feature has not been officially released yet. It is planned for KawaiiPhysics v1.22. Specifications may change during development.

Overview​

You may want softer hair at a landing or looser clothing during an attack. If timing is driven only by gameplay events, revising the animation also requires adjusting when those calls occur.

The new Notifies record multiplier or gust timing on the animation. They help artists adjust the event time or interval. Use these alongside the existing external-force and Alpha Notifies described above.

Notify Types​

GoalType
Change motion for a duration after an eventKawaiiPhysics: Settings Multiplier (Pulse)
Apply multipliers during an action intervalNotifyState KawaiiPhysics: Settings Multiplier
Trigger a gust with the animationKawaiiPhysics: Trigger Gust

Adding Settings Multiplier (Pulse)​

  1. Open the Animation Sequence.
  2. Select the time when the effect should begin.
  3. Add KawaiiPhysics: Settings Multiplier (Pulse) on the Notify track (the following setting is an example).
  4. Set Stiffness in SettingsScale to 0.5; leave other scales at 1.
  5. Play and compare motion before and after the Notify.

Settings Multiplier (Pulse)​

Duration includes both fades. Zero or negative Duration does nothing. Pulse does not keep a stop handle; use NotifyState or an API for an event requiring early release.

Settings Multiplier NotifyState​

NotifyState applies SettingsScale over its interval. Curve uses the animation curve named by CurveName as weight.

Envelope accumulates NotifyTick FrameDeltaTime. It may drift from the interval with changed PlayRate, reverse playback, or scrubbing. Use Curve when the weight must follow animation time under those conditions. Missing curves default to weight 1, so check the curve name.

When a Montage is interrupted, or Curve mode ends, the current weight fades out over BlendOutTime. Check that interrupted playback returns as intended too.

Trigger Gust​

Add an enabled Procedural Wind to the target node's External Forces. Leaving Gust Direction at zero inherits direction and related settings from that wind.

Add KawaiiPhysics: Trigger Gust to the Notify track, set Strength, RiseTime, HoldTime, and DecayTime, then play the animation. Strength defaults to 0, which produces no gust.

For this mesh, use Gust Target=Kawaii Physics Nodes. To send to hair and clothing together, prepare a Kawaii Physics Shared Publisher, select Shared Publisher, and match SharedPublisherTag. Filter Tags and Gust Direction are not used in that mode.

Property and playback contracts

Related UE documentation​

  • Animation Notifies — Review Notify tracks, NotifyState intervals, and event firing conditions. (UE 5.8)