UBlueprintSpringMathLibrary::CriticalSpringDampVector

function Engine Blueprint Since 5.7

#include "Kismet/BlueprintSpringMathLibrary.h"

Access: public Specifiers: staticBlueprintCallable

Description

Interpolates InOutX towards TargetX using the motion of a critically damped spring, storing the resulting velocity back into InOutV. Commonly used to smooth a camera or follow-target position.

Caveats & Gotchas

• Marked UE_EXPERIMENTAL(5.7, "SpringMath is experimental") — behaviour and defaults may change in later engine versions.
• InOutX and InOutV must be persisted by the caller between calls (e.g. as member variables on an actor or component); each axis is damped independently, so uneven per-axis targets can produce a curved rather than straight-line approach.
• This is functionally equivalent in intent to UKismetMathLibrary::VectorSpringInterp but has a simpler parameter set with no exposed spring-state struct — use the KismetMathLibrary version if you need to reset or inspect spring state explicitly.

Signature

static void CriticalSpringDampVector(UPARAM(ref) FVector& InOutX, UPARAM(ref) FVector& InOutV, const FVector& TargetX, float DeltaTime, float SmoothingTime = 0.2f);

Parameters

Name	Type	Description	Default
InOutX	FVector&	The value to be damped; updated in place each call.	—
InOutV	FVector&	The velocity of the damped value; must be persisted by the caller between calls.	—
TargetX	const FVector&	The goal value to damp towards.	—
DeltaTime	float	Timestep in seconds.	—
SmoothingTime	float	Smoothing time for the spring. Larger values give more damped behaviour; 0 snaps InOutX to TargetX.	0.2f

Return Type

void

Example

Smooth a spring-arm target location C++

FVector SmoothedLocation = GetActorLocation();
FVector SmoothedVelocity = FVector::ZeroVector;

void AMyFollowCam::Tick(float DeltaTime)
{
    Super::Tick(DeltaTime);
    UBlueprintSpringMathLibrary::CriticalSpringDampVector(SmoothedLocation, SmoothedVelocity, TargetActor->GetActorLocation(), DeltaTime, 0.3f);
    SetActorLocation(SmoothedLocation);
}

Version History

Introduced in: 5.7

Version	Status	Notes
5.7	experimental	SpringMath is experimental.

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