更改类 Unreal C++ 其他部分的值答案

【问题标题】：Changing values in other parts of a class Unreal C++更改类 Unreal C++ 其他部分的值
【发布时间】：2017-08-07 10:13:35
【问题描述】：

基本上，我想增加一个对象的 Z 轴每个刻度。我可以在蓝图中做到这一点，但我似乎无法弄清楚如何从滴答声中访问类的开始播放部分并增加 ActorLocation。

    // 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);

    // ...
}

【问题讨论】：

标签： c++ unreal-engine4

【解决方案1】：

在UMoveUp:BeginPlay() 中，您可以设置初始值。它只被调用一次，当actor被生成时。你想用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 值可以（并且将会）随着时间而改变，而且它还取决于游戏（视觉）设置和用户的 PC。使用DeltaTime 可确保无论帧率如何都能获得相同的体验。

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

【讨论】：