Smoothing Visual Jitter During State Corrections

In this lesson, you will learn how to mask the jarring "snap" that occurs when a server overrides a local client's predicted movement, ensuring your character’s motion remains fluid even when corrections are necessary.

The Conflict of Authority

When you implement Client-Side Prediction, your local client moves instantly to provide responsiveness. However, if the server calculates a different position—perhaps due to a collision or latency variance—it sends a correction. If you simply teleport the character to the server’s coordinate, the player experiences a "visual stutter" or jitter. To fix this, we decouple the actual collision-capable mesh location from the visual mesh location.

Implementing Visual Blending

Instead of forcing the Actor's root component to snap to the server's authoritative position, we allow the Actor to snap instantly (to maintain physical integrity) while the Mesh Component performs a smooth transition.

We achieve this by storing the "error" (the delta between the old location and the corrected location) and applying a decay function over time to the mesh's relative offset.

// Inside your Character class or Movement Component
void AMyCharacter::OnServerCorrection(FVector ServerLocation)
{
    // 1. Calculate the offset between current visual pos and new server pos
    FVector ErrorOffset = GetActorLocation() - ServerLocation;
    
    // 2. Snap the logical actor immediately to satisfy physics
    SetActorLocation(ServerLocation);
    
    // 3. Offset the visual mesh back to the previous position
    GetMesh()->SetRelativeLocation(ErrorOffset);
}

void AMyCharacter::Tick(float DeltaTime)
{
    // 4. Smoothly interpolate the mesh offset back to zero
    FVector CurrentOffset = GetMesh()->GetRelativeLocation();
    FVector NewOffset = FMath::VInterpTo(CurrentOffset, FVector::ZeroVector, DeltaTime, InterpSpeed);
    
    GetMesh()->SetRelativeLocation(NewOffset);
}

Why This Works

By offsetting the visual mesh in the opposite direction of the snap, we create a frame where the character appears to be in the "old" position. Over the next few frames, the FMath::VInterpTo function gradually pulls the mesh back to the actor's root. The result is a smooth glide toward the correct position rather than an instant, frame-perfect jump that breaks player immersion.

Key Takeaway: Never snap the visual representation directly; instead, snap the physical state and interpolate the visual mesh offset to hide the correction.