FMath::ExponentialSmoothingApprox
#include "Math/UnrealMathUtility.h"
Access: public
Specifiers: staticconstexpr
Description
Smooths a value towards a target using an exponential decay approximation. Uses InvExpApprox internally which is cheaper than a true exp() but still frame-rate independent.
Caveats & Gotchas
- • The approximation is accurate when InDeltaTime < InSmoothingTime. At very large delta times relative to InSmoothingTime the approximation diverges from true exponential — prefer CriticallyDampedSmoothing or SpringDamper when frames may stall.
- • When InSmoothingTime is zero (or near UE_KINDA_SMALL_NUMBER), the value is snapped immediately to InTargetValue without smoothing.
- • This function tracks velocity-independent targets only — it has no notion of target velocity. If your target is itself moving, use CriticallyDampedSmoothing to avoid permanent lag.
Signature
template< class T >
static constexpr void ExponentialSmoothingApprox(T& InOutValue, const T& InTargetValue, const float InDeltaTime, const float InSmoothingTime)Parameters
| Name | Type | Description | Default |
|---|---|---|---|
| InOutValue | T& | The value to be smoothed. Modified in place. | — |
| InTargetValue | const T& | The target value to smooth towards. | — |
| InDeltaTime | const float | Elapsed time since last update. | — |
| InSmoothingTime | const float | Timescale over which to smooth. Larger values mean more smoothed behaviour. Can be zero. | — |
Return Type
void Example
Smooth a rotation yaw towards a target each tick C++
void AMyPawn::Tick(float DeltaTime)
{
Super::Tick(DeltaTime);
FMath::ExponentialSmoothingApprox(CurrentYaw, TargetYaw, DeltaTime, 0.1f);
SetActorRotation(FRotator(0.f, CurrentYaw, 0.f));
}Tags
Version History
Introduced in: 4.20
| Version | Status | Notes |
|---|---|---|
| 5.6 | stable | — |
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