非实文档中教程项目中的错误

Question

我第一次尝试学习C++/UE4，教程中提供的代码(在他们自己的文档中)会抛出错误。我如何解决这个问题和/或找到一个有效的教程？

我试图在https://docs.unrealengine.com/en-US/Programming/Tutorials/PlayerInput/index.html上完成本教程，但是步骤1中提供的代码会引发错误。

我已经尝试过“潜在的修复”，并在网上环顾四周，但没有发现任何可以修复错误的地方。

AMyPawn::AMyPawn() { //将此典当设置为调用Tick()每个帧。如果你不需要的话，你可以关掉它来提高性能。PrimaryActorTick.bCanEverTick =真；

// Set this pawn to be controlled by the lowest-numbered player
AutoPossessPlayer = EAutoReceiveInput::Player0;

// Create a dummy root component we can attach things to.
RootComponent = CreateDefaultSubobject<USceneComponent>(TEXT("RootComponent"));
// Create a camera and a visible object

UCameraComponent* OurCamera = CreateDefaultSubobject<UCameraComponent>(TEXT("OurCamera"));
OurVisibleComponent = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("OurVisibleComponent"));
// Attach our camera and visible object to our root component. Offset and rotate the camera.
OurCamera->SetupAttachment(RootComponent);
OurCamera->SetRelativeLocation(FVector(-250.0f, 0.0f, 250.0f));
OurCamera->SetRelativeRotation(FRotator(-45.0f, 0.0f, 0.0f));
OurVisibleComponent->SetupAttachment(RootComponent);

}

错误C2065 'UCameraComponent'：未声明的标识符

错误C2065 'OurCamera'：未声明的标识符

错误C2672 'UObject::CreateDefaultSubobject'：没有找到匹配的重载函数

错误C2974 'UObject::CreateDefaultSubobject'：“TReturnType”的无效模板参数，类型预期

错误命令“C：\Program\Epic Games\UE_4.22\Engine\Build\BatchFiles\Build.bat”SecondUnrealProjectEditor Win64 Win64 Development -WaitMutex -FromMsBuild“与代码5一起退出。请验证您是否有足够的权限运行此命令。

我期望代码运行时不会出现错误，因为我完全遵循了本教程(事实上，我已经复制粘贴了“工作”代码，以检查我没有意外地更改任何内容)。

Answer 1

第一个错误意味着编译器找不到UCameraComponent的声明，其他错误只是后续错误。

您需要在MyPawn.cpp中添加以下内容

#include "Camera/CameraComponent.h"

修复后，您将得到另一个错误，这一次，因为UStaticMeshComponent的声明丢失了。为此，您需要以下内容：

#include "Components/StaticMeshComponent.h"

错误消息是不同的，因为在第一种情况下，编译器希望实例化一个未知类型的对象，这是不可能的，而在后一种情况下，编译器希望将未知类型的UStaticMeshComponent指针分配给另一个已知类型USceneComponent的指针，而且它不知道UStaticMeshComponent可以转换为USceneComponent。

我同意教程忽略了这一点是很糟糕的，但是用正确的工具找一个缺失的包含是相当容易的。在Visual中，您只需在保存UCameraComponent时单击任何类型(例如，Ctrl )，它将直接转到声明中，或者它将向您显示具有潜在声明的文件列表。

在“虚幻”中，通常情况是，对于每个组件，包含文件都有该组件的名称，因此对于UCameraComponent，它是CameraComponent.h，它驻留在子文件夹Camera中。

Answer 2

我也遇到过这个问题。我已经完成了一些修改的教程。视频工作室2019 14.24.28315 UE4 4.24

MyPawn.h

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Pawn.h"
#include "Camera/CameraComponent.h"
#include "GameFramework/Character.h"
#include "MyPawn.generated.h"

UCLASS()
class HOWTO_PLAYERINPUT_API AMyPawn : public APawn
{
    GENERATED_BODY()

public:
    // Sets default values for this pawn's properties
    AMyPawn();

protected:
    // Called when the game starts or when spawned
    virtual void BeginPlay() override;

public: 
    // Called every frame
    virtual void Tick(float DeltaTime) override;

    // Called to bind functionality to input
    virtual void SetupPlayerInputComponent(class UInputComponent* PlayerInputComponent) override;

    UPROPERTY(EditAnywhere)
    USceneComponent* OurVisibleComponent;

    //Input functions
    void Move_XAxis(float AxisValue);
    void Move_YAxis(float AxisValue);
    void StartGrowing();
    void StopGrowing();

    //Input variables
    FVector CurrentVelocity;
    bool bGrowing;

};

MyPawn.cpp

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


#include "MyPawn.h"
#include "Camera/CameraComponent.h"
#include "Components/StaticMeshComponent.h"

// Sets default values
AMyPawn::AMyPawn()
{
    // Set this pawn to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
    PrimaryActorTick.bCanEverTick = true;

    // Set this pawn to be controlled by the lowest-numbered player
    AutoPossessPlayer = EAutoReceiveInput::Player0;

    // Create a dummy root component we can attach things to.
    RootComponent = CreateDefaultSubobject<USceneComponent>(TEXT("RootComponent"));
    // Create a camera and a visible object
    UPROPERTY(EditAnywhere)
    UCameraComponent* OurCamera = CreateDefaultSubobject<UCameraComponent>(TEXT("OurCamera"));
    OurVisibleComponent = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("OurVisibleComponent"));
    // Attach our camera and visible object to our root component. Offset and rotate the camera.
    OurCamera->SetupAttachment(RootComponent);
    OurCamera->SetRelativeLocation(FVector(-250.0f, 0.0f, 250.0f));
    OurCamera->SetRelativeRotation(FRotator(-45.0f, 0.0f, 0.0f));
    OurVisibleComponent->SetupAttachment(OurCamera);
    OurVisibleComponent->SetRelativeLocation(FVector(268.0f, 0.0f, -14.14f));
    OurVisibleComponent->SetRelativeRotation(FRotator(45.0f, 0.0f, 0.0f));


}

// Called when the game starts or when spawned
void AMyPawn::BeginPlay()
{
    Super::BeginPlay();

}

// Called every frame
void AMyPawn::Tick(float DeltaTime)
{
    Super::Tick(DeltaTime);

    // Handle growing and shrinking based on our "Grow" action

    float CurrentScale = OurVisibleComponent->GetComponentScale().X;
    if (bGrowing)
    {
        // Grow to double size over the course of one second
        CurrentScale += DeltaTime;
    }
    else
    {
        // Shrink half as fast as we grow
        CurrentScale -= (DeltaTime * 0.5f);
    }
    // Make sure we never drop below our starting size, or increase past double size.
    CurrentScale = FMath::Clamp(CurrentScale, 1.0f, 2.0f);
    OurVisibleComponent->SetWorldScale3D(FVector(CurrentScale));


    // Handle movement based on our "MoveX" and "MoveY" axes

    if (!CurrentVelocity.IsZero())
    {
        FVector NewLocation = GetActorLocation() + (CurrentVelocity * DeltaTime);
        SetActorLocation(NewLocation);
    }


}

// Called to bind functionality to input
void AMyPawn::SetupPlayerInputComponent(UInputComponent* PlayerInputComponent)
{
    Super::SetupPlayerInputComponent(PlayerInputComponent);

    // Respond when our "Grow" key is pressed or released.
    PlayerInputComponent->BindAction("Grow", IE_Pressed, this, &AMyPawn::StartGrowing);
    PlayerInputComponent->BindAction("Grow", IE_Released, this, &AMyPawn::StopGrowing);

    // Respond every frame to the values of our two movement axes, "MoveX" and "MoveY".
    PlayerInputComponent->BindAxis("MoveX", this, &AMyPawn::Move_XAxis);
    PlayerInputComponent->BindAxis("MoveY", this, &AMyPawn::Move_YAxis);

}

void AMyPawn::Move_XAxis(float AxisValue)
{
    // Move at 100 units per second forward or backward
    CurrentVelocity.X = FMath::Clamp(AxisValue, -1.0f, 1.0f) * 100.0f;
}

void AMyPawn::Move_YAxis(float AxisValue)
{
    // Move at 100 units per second right or left
    CurrentVelocity.Y = FMath::Clamp(AxisValue, -1.0f, 1.0f) * 100.0f;
}

void AMyPawn::StartGrowing()
{
    bGrowing = true;
}

void AMyPawn::StopGrowing()
{
    bGrowing = false;
}

我只是觉得疯狂的是，每次UE4更新的时候，基本上每个教程都会下地狱。*注:本教程完成后，我摸索了一下。我在UE4工作，没有花时间“正确”地写这段代码，所以如果有什么错误的风格/惯例，我很抱歉;)