External Forces Parameters

Parameters related to externally applied forces.

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Gravity

Gravity

Gravity - Gravity vector applied to bones.

Property	Value
Type	FVector
Default	(0, 0, 0)
Category	Force

// Apply downward gravity
Gravity = FVector(0, 0, -1.0f);

bUseLegacyGravity

Legacy Gravity Method - Specifies the Gravity application method.

Property	Value
Type	bool
Default	false
Category	Force

Value	Description
true	Legacy compatible (adds 0.5 * Gravity * dt^2 to position)
false	AnimDynamics compatible (adds Gravity * dt to velocity, then updates position)

bUseDefaultGravityZProjectSetting

Use Project Setting Gravity - Flag to multiply Gravity vector by the project setting's DefaultGravityZ (absolute value).

Property	Value
Type	bool
Default	false
Category	Force

bUseWorldSpaceGravity

World Space Gravity - Flag for whether to handle gravity in world coordinate system.

Property	Value
Type	bool
Default	true
Category	Force

Wind

bEnableWind

Enable Wind - Flag for whether to receive influence from WindDirectionalSource as external force.

Property	Value
Type	bool
Default	false
Category	Force

WindScale

Wind Scale - Influence degree of wind from WindDirectionalSource. Used for compatibility with Cloth and SpeedTree.

Property	Value
Type	float
Default	1.0
Edit Condition	bEnableWind == true
Category	Force

note

WindScale is only effective when bEnableWind is true.

WindDirectionNoiseAngle

Wind Direction Noise - Noise (angle) applied to wind direction from WindDirectionalSource. Adds randomness to the wind direction to soften mechanical-looking sway.

Property	Value
Type	float
Default	0.0
Unit	Degrees
Range	0 or higher
Edit Condition	bEnableWind == true
Category	Force

Simple External Force

SimpleExternalForce

Simple External Force Vector - Allows applying force in any direction.

Property	Value
Type	FVector
Default	(0, 0, 0)
Category	Force|External Force

bUseWorldSpaceSimpleExternalForce

World Space External Force - Flag for whether to handle simple external force in world coordinate system.

Property	Value
Type	bool
Default	true
Category	Force|External Force

External Force Presets

ExternalForces

External Force Presets (Instanced Struct) - External force presets. Custom presets can be added in C++.

UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Force|External Force",
    meta = (BaseStruct = "/Script/KawaiiPhysics.KawaiiPhysics_ExternalForce", ExcludeBaseStruct))
TArray<FInstancedStruct> ExternalForces;

CustomExternalForces (Experimental)

Custom External Forces (Instanced Property) - Custom presets can be added in BP/C++.

UPROPERTY(EditAnywhere, BlueprintReadWrite, Instanced, Category = "Force|External Force",
    meta=(DisplayName="CustomExternalForces(EXPERIMENTAL)"))
TArray<TObjectPtr<UKawaiiPhysics_CustomExternalForce>> CustomExternalForces;

warning

This feature is highly experimental. It may not work properly unless you click on the AnimNode or compile the Animation Blueprint.

Tag

KawaiiPhysicsTag

Filtering Tag - GameplayTag for filtering, used with ExternalForce, etc.

Property	Value
Type	FGameplayTag
Category	Tag

// Apply external force using tag
FGameplayTagContainer FilterTags;
FilterTags.AddTag(FGameplayTag::RequestGameplayTag("KawaiiPhysics.Hair"));
UKawaiiPhysicsLibrary::AddExternalForcesToComponent(MeshComp, ExternalForces, Owner, FilterTags);

Runtime Control / Blueprint API

External forces can be added and removed dynamically from Blueprint (AddExternalForce / AddExternalForcesToComponent / RemoveExternalForcesFromComponent). See the following for steps and signatures.

• How-to flow: Runtime Control
• Full function list: UKawaiiPhysicsLibrary

Related Pages

This page is the reference for external-force parameters. For actual usage, see the following guides.

• Wind and External Forces — basic usage of wind, gravity, and external forces (introductory)
• External Force Presets — details of the Basic / Curve / Gravity / Wind presets
• Custom Gravity — customizing gravity direction
• AnimNotify — controlling external forces during animation