c++ - 更改类的其他部分的值 Unreal C++

Question

基本上，我想在对象的每个刻度上增加 Z 轴。我可以在 Blueprint 中做到这一点，但我似乎无法弄清楚如何从滴答和增量 ActorLocation 访问类的开始播放部分。

    // Fill out your copyright notice in the Description page of Project Settings.

#include "MoveUp.h"
#include "GameFramework/Actor.h"


// Sets default values for this component's properties
UMoveUp::UMoveUp()
{
    // Set this component to be initialized when the game starts, and to be ticked every frame.  You can turn these features
    // off to improve performance if you don't need them.
    PrimaryComponentTick.bCanEverTick = true;

    // ...
}


// Called when the game starts
void UMoveUp::BeginPlay()
{
    Super::BeginPlay();
    AActor* Owner = GetOwner();
    FVector ActorLocation = FVector(0.f,0.f,200.f);
    Owner->SetActorLocation(ActorLocation, false) ;
}


// Called every frame
void UMoveUp::TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction)
{
    Super::TickComponent(DeltaTime, TickType, ThisTickFunction);

    // ...
}

Answer 1

在UMoveUp:BeginPlay()中，您可以设置初始值。它只在 actor 生成时被调用一次。你想使用 TickComponent:

// Called every frame
void UMoveUp::TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction)
{
    Super::TickComponent(DeltaTime, TickType, ThisTickFunction);

    // this could be "cached" as private property - better performance
    auto owner = GetOwner();  

    // now we need to actually move by Delta * base value
    // note that we are ignoring actor's rotation
    auto newActorLocation = owner->GetActorLocation() + FVector(0.f,0.f,200.f) * DeltaTime;  

    owner->SetActorLocation(newActorLocation, false);
}

使用 DeltaTime 很重要，因为您的 FPS 值会(并且会)随时间变化，而且它还取决于游戏(视觉)设置和用户的 PC。无论帧率如何，使用 DeltaTime 确保相同的体验。

另一种可能的方法是使用 UPrimitiveComponent::AddForce(...) ( UE Docs )。这是一种更基于物理学的方法，适用于更复杂的模拟。