UE5 C++ 定时器 案例练习

一.这里参照 官方案例

Quick Start Guide to Variables Timers and Events in Unreal Engine CPP | 虚幻引擎 5.6 文档 | Epic Developer Community

二.

UPrimitiveComponent 是涉及渲染的组件，三角面的渲染几何等等。渲染线程它不能用U开头的东西，它会在这里把数据转换为F开头的结构体，把数据传递给渲染现场。

 * PrimitiveComponents are SceneComponents that contain or generate some sort of geometry, generally to be rendered or used as collision data.。

// Fill out your copyright notice in the Description page of Project Settings.#pragma once#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "CountdownActor.generated.h"UCLASS()
class THIRDLEARN_API ACountdownActor : public AActor
{GENERATED_BODY()public:	// Sets default values for this actor's propertiesACountdownActor();class UTextRenderComponent* CountdownText;
protected:// Called when the game starts or when spawnedvirtual void BeginPlay() override;void UpdateTimeDisplay();void AdvanceTimer();void CountdownHasFinished();public:	// Called every framevirtual void Tick(float DeltaTime) override;
protected:int32 CountdonwTime = 3;FTimerHandle CountTimer;};

UpdateTimeDisplay()更新，在BeginPlay一开始的时候就更新一次，并设置好定时器。

定时器，AdvanceTimer 减少计时，更新显示的位置。并判断是否要消除计时器，再最后清楚的时候，更新文本。

// Fill out your copyright notice in the Description page of Project Settings.#include "CountdownActor.h"
#include "Components/TextRenderComponent.h"// Sets default values
ACountdownActor::ACountdownActor()
{// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.PrimaryActorTick.bCanEverTick = false;CountdownText = CreateDefaultSubobject<UTextRenderComponent>("CountdownTime");CountdownText->SetHorizontalAlignment(EHTA_Center);CountdownText->SetWorldSize(150);RootComponent = CountdownText;CountdonwTime = 3;
}// Called when the game starts or when spawned
void ACountdownActor::BeginPlay()
{Super::BeginPlay();UpdateTimeDisplay();GetWorldTimerManager().SetTimer(CountTimer, this, &ACountdownActor::AdvanceTimer, 1.0f, true);
}// Called every frame
void ACountdownActor::Tick(float DeltaTime)
{Super::Tick(DeltaTime);}void ACountdownActor::UpdateTimeDisplay()
{CountdownText->SetText(FText::FromString(FString::FromInt(FMath::Max(CountdonwTime, 0))));
}void ACountdownActor::AdvanceTimer()
{--CountdonwTime;UpdateTimeDisplay();if (CountdonwTime < 0){GetWorldTimerManager().ClearTimer(CountTimer);CountdownHasFinished();}
}void ACountdownActor::CountdownHasFinished()
{CountdownText->SetText(FText::FromString(TEXT("GO")));
}// Called every frame
void ACountdownActor::Tick(float DeltaTime)
{Super::Tick(DeltaTime);}void ACountdownActor::UpdateTimeDisplay()
{CountdownText->SetText(FText::FromString(FString::FromInt(FMath::Max(CountdonwTime,0))));
}void ACountdownActor::AdvanceTimer()
{ --CountdonwTime;
}void ACountdownActor::CountdownHasFinished()
{CountdownText->SetText(FText::FromString(TEXT("GO")));
}