> Do For Duration

USCFlowDoForDuration

Available in: C++ and Blueprint. UBlueprintAsyncActionBase, BlueprintType, proxy pin Action. Module StillCookingCore, header Flow/SCFlowDoForDuration.h. Category StillCooking|Flow. Built on FSCFlowDuration. Placeable on an event graph only, like every Flow node.

Drives an alpha from 0 to 1 over Duration seconds, firing On Update every frame and then Completed. Unlike a hand-written Alpha += DeltaTime / Duration loop, it delivers the final update at alpha 1 instead of skipping it when the last frame overshoots.

DoForDuration(...)

• C++ call — USCFlowDoForDuration::DoForDuration(WorldContextObject, Duration, Curve, bUseUnscaledTime, bTickWhenPaused), then Activate()
• Blueprint node — Do For Duration

The first On Update lands on the first tick after activation, one delta in — the alpha starts at DeltaTime / Duration, not at 0. A paused drive without Tick When Paused banks no time: it freezes, and resumes one update per frame on unpause. The two advanced pins are independent — what each one decides.

The final-frame guarantee

The last On Update is guaranteed to land at the end of the drive: with no curve, at an alpha of exactly 1. The update goes out before the completion test, so the frame that reaches or overshoots the duration still delivers, at raw progress clamped to 1.

The guarantee attaches to raw progress, not to the delivered alpha. With a curve set, the last update carries the curve’s value at time 1 — whatever its author drew there. A curve ending at 0.5 delivers 0.5 last; a curve that overshoots past 1 and settles back delivers its overshoot on the way and its final value at the end. The curve’s output is not clamped: clamping it would silently flatten an overshoot its author drew on purpose.

The Curve pin

The drive’s raw 0..1 progress is looked up on the curve and the result is what On Update receives. The node holds the asset and consults it every frame while the asset is valid; a curve collected before the drive ends degrades the lookup to the identity rather than reading a dead asset.

A curve built in code works the same as an asset, with the delegate binding and Activate() that any node driven from C++ needs:

TStrongObjectPtr<UCurveFloat> Curve(NewObject<UCurveFloat>());
Curve->FloatCurve.AddKey(0.f, 0.f);
Curve->FloatCurve.AddKey(1.f, 0.5f);

USCFlowDoForDuration* Node = USCFlowDoForDuration::DoForDuration(World, /*Duration*/ 1.f, Curve.Get());
Node->OnUpdate.AddDynamic(Listener, &UMyListener::HandleUpdate);       // UFUNCTION() void HandleUpdate(float Alpha, float DeltaTime)
Node->Completed.AddDynamic(Listener, &UMyListener::HandleCompleted);   // UFUNCTION() void HandleCompleted(bool bCompletedFully)
Node->Activate();
// the last delivered alpha is 0.5 — the curve's value at one — not 1

Functions

Outputs

Completed does not fire when the world is torn down under the drive.

In Blueprint the node’s data pins are Alpha and Delta Time, from On Update. On the Completed path they still hold the last values delivered — why Completed carries no reason.

Messages

One, on LogStillCooking: an Error when the world context resolved no world, after which nothing fires. Its exact wording is with the message every Flow node can write.

Pitfalls

• Read Alpha as the value to apply, not as a fraction of time. With a curve, Alpha is the curve’s output and can exceed 1.
• A second Activate() on the same node is ignored. Call Do For Duration again for a new drive.
• Cancelling from inside the update callback. On the C++ core, a Cancel() issued from inside the update lambda — directly, or through the node’s Cancel called from On Update — destroys that lambda while it is still on the stack. A Cancel from inside On Update works today only because the node’s own handler reads nothing after that point; a future change could break it. In C++, make the cancelling statement the last one that touches a capture. Details in C++ Flow cores.