UBlueprintSpringMathLibrary::VelocitySpringCharacterUpdate

function Engine Blueprint Since 5.7

#include "Kismet/BlueprintSpringMathLibrary.h"

Access: public Specifiers: staticBlueprintCallable

Description

Advances a character's position toward a target velocity using a velocity spring that tracks an intermediate velocity moving at a capped maximum acceleration. Unlike SpringCharacterUpdate, larger jumps in TargetVelocity take proportionally longer to reach because acceleration is clamped by MaxAcceleration.

Caveats & Gotchas

• Marked UE_EXPERIMENTAL(5.7, "SpringMath is experimental") — behaviour and defaults may change in later engine versions.
• InOutVelocity, InOutVelocityIntermediate, and InOutAcceleration are all caller-owned state that must persist between calls — resetting any of them to zero mid-sequence produces a visible pop in motion.
• MaxAcceleration defaults to 1.0, which is very low for world-unit velocities (cm/s) — leaving it at the default typically makes the character feel like it never reaches TargetVelocity; tune it to the scale of your movement speeds.

Signature

static void VelocitySpringCharacterUpdate(UPARAM(ref) FVector& InOutPosition, UPARAM(ref) FVector& InOutVelocity, UPARAM(ref) FVector& InOutVelocityIntermediate, UPARAM(ref) FVector& InOutAcceleration, const FVector& TargetVelocity, float DeltaTime, float SmoothingTime = 0.2f, float MaxAcceleration = 1.0f);

Parameters

Name	Type	Description	Default
InOutPosition	FVector&	The position of the character; updated in place each call.	—
InOutVelocity	FVector&	The velocity of the character. Must be stored and persisted by the caller between calls, usually starting at zero.	—
InOutVelocityIntermediate	FVector&	The intermediate target velocity of the character. Must be stored and persisted by the caller between calls, usually starting at zero.	—
InOutAcceleration	FVector&	The acceleration of the character. Must be stored and persisted by the caller between calls, usually starting at zero.	—
TargetVelocity	const FVector&	The target velocity of the character.	—
DeltaTime	float	The delta time to tick the character.	—
SmoothingTime	float	The time over which to smooth velocity; it takes roughly this long for the character to reach the target velocity.	0.2f
MaxAcceleration	float	Caps the acceleration the intermediate velocity can apply each frame. A very large value makes this behave like SpringCharacterUpdate.	1.0f

Return Type

void

Example

Advance a character position with a clamped-acceleration velocity spring C++

FVector Position = GetActorLocation();
FVector Velocity = FVector::ZeroVector;
FVector VelocityIntermediate = FVector::ZeroVector;
FVector Acceleration = FVector::ZeroVector;

void AMyCharacter::Tick(float DeltaTime)
{
    Super::Tick(DeltaTime);
    UBlueprintSpringMathLibrary::VelocitySpringCharacterUpdate(
        Position, Velocity, VelocityIntermediate, Acceleration,
        DesiredVelocity, DeltaTime, 0.25f, 800.f);
    SetActorLocation(Position);
}

Version History

Introduced in: 5.7

Version	Status	Notes
5.7	experimental	SpringMath is experimental.

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