Timeline in c++

How to use Timeline in C++

This example gives an idea about how to use timelines in C++.

YourClass.h

#include "Components/TimelineComponent.h"

UCLASS()
class YOURGAME_API AYourClass: public AActor {

protected:
    UPROPERTY()
    UTimelineComponent* MyTimeline;
 
    UPROPERTY()
    UCurveFloat* FloatCurve;

    UFUNCTION()
    void TimelineCallback(float val);
    
    UFUNCTION()
    void TimelineFinishedCallback();

    void PlayTimeline();

    UPROPERTY()
    TEnumAsByte<ETimelineDirection::Type> TimelineDirection;   

public:

    AYourClass();
};

YourClass.cpp

AYourClass::AYourClass()
{
    static ConstructorHelpers::FObjectFinder Curve(TEXT("/Game/Curves/C_MyCurve"));
    check(Curve.Succeeded());
    
    FloatCurve = Curve.Object;
}

void AYourClass::BeginPlay()
{
    FOnTimelineFloat onTimelineCallback;
    FOnTimelineEventStatic onTimelineFinishedCallback;

    Super::BeginPlay();
        
    if (FloatCurve != NULL)
    {
        MyTimeline = NewObject(this, FName("TimelineAnimation"));
        MyTimeline->CreationMethod = EComponentCreationMethod::UserConstructionScript; // Indicate it comes from a blueprint so it gets cleared when we rerun construction scripts
        this->BlueprintCreatedComponents.Add(MyTimeline); // Add to array so it gets saved
        MyTimeline->SetNetAddressable();    // This component has a stable name that can be referenced for replication

        MyTimeline->SetPropertySetObject(this); // Set which object the timeline should drive properties on
        MyTimeline->SetDirectionPropertyName(FName("TimelineDirection"));

        MyTimeline->SetLooping(false);
        MyTimeline->SetTimelineLength(5.0f);
        MyTimeline->SetTimelineLengthMode(ETimelineLengthMode::TL_LastKeyFrame);

        MyTimeline->SetPlaybackPosition(0.0f, false);

        //Add the float curve to the timeline and connect it to your timelines's interpolation function
        onTimelineCallback.BindUFunction(this, FName{ TEXT("TimelineCallback") });
        onTimelineFinishedCallback.BindUFunction(this, FName{ TEXT("TimelineFinishedCallback") });
        MyTimeline->AddInterpFloat(FloatCurve, onTimelineCallback);
        MyTimeline->SetTimelineFinishedFunc(onTimelineFinishedCallback);

        MyTimeline->RegisterComponent();
    }
}

void AYourClass::Tick(float deltaTime)
{
    Super::Tick(deltaTime);

    if (MyTimeline != NULL)
    {
        MyTimeline->TickComponent(deltaTime, ELevelTick::LEVELTICK_TimeOnly, NULL);
    }
}

void AYourClass::TimelineCallback(float interpolatedVal)
{
    // This function is called for every tick in the timeline.
}

void AYourClass::TimelineFinishedCallback()
{
    // This function is called when the timeline finishes playing.
}

void AYourClass::PlayTimeline()
{
    if (MyTimeline != NULL)
    {
        MyTimeline->PlayFromStart();
    }
}

If you need to get the value of another curve in your callback function, get the playback position of the timeline and use it to get the corresponding value on the other curve.

OtherFloatCurve->GetFloatValue(MyTimeline->GetPlaybackPosition());
OtherVectorCurve->GetVectorValue(42.0f);

You may want to add the curves to your existing timeline and bind a function to be called back instead.

Relevant API Documentation

• UTimelineComponent
• UFloatVector
• UCurveVector
• UCurveLinearColor

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