UE（虚幻）学习（四）第一个C++类来控制小球移动来理解蓝图和脚本如何工作

UE5视频看了不少，但基本都是蓝图如何搞，或者改一下属性，理解UE系统现有组件使用的。一直对C++脚本和蓝图之间的关系不是很理解，看到一个视频讲的很好，我也做笔记记录一下。

我的环境是UE5.3.2.

创建UE空项目

我们创建一个空项目
在这里插入图片描述

创建类MyPlayer

进入项目后，我们直接创建一个C++类。
在这里插入图片描述
因为是从基础理解，所以就选择更基础的Pawn类，不使用Character类。

我起名字MyPlayer类。确定后就提示会

之前创建的是蓝图项目，创建类后就包含源码了，需要关闭UE重新进入。

进入后我们就可以看到自己建立的类了。
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如果你看不到C++Classes，请掉右边的Settings，并勾选Show C++ Classes。

这里我重新创建了类名BallPlayer，不喜欢之前的MyPlayer的名字，就不附上截图了。

查看新生成的文件

我们用VS打开项目，可以看到.h和.cpp文件，内容如下：

BallPlayer.h

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

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Pawn.h"
#include "BallPlayer.generated.h"

UCLASS()
class MYPROJECT4_API ABallPlayer : public APawn
{
	GENERATED_BODY()

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

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;

};

BallPlayer.cpp

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


#include "BallPlayer.h"

// Sets default values
ABallPlayer::ABallPlayer()
{
 	// 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;

}

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

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

}

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

}

UE的类前面自动添加了A字母。继承于APawn。

修改代码

下面我们添加一些代码：
BallPlayer.h文件中添加了三个组件：模型Mesh，弹簧，相机。
Mesh就是我们控制看到的小球（UStaticMeshComponent），弹簧（USpringArmComponent）就是用来控制相机和小球之间的距离，相机（UCameraComponent）就是我们的画面视角。

然后MoveForce和JumpForce是控制的物理力大小。

方法：
MoveRight是用来处理左右移动的
MoveForward是用来处理前后移动的
Jump是跳跃

这里注意下头文件，引用的文件要写在#include "BallPlayer.generated.h"的前面。

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

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Pawn.h"
#include "Camera/CameraComponent.h"
#include "GameFramework/SpringArmComponent.h"

#include "BallPlayer.generated.h"


UCLASS()
class MYPROJECT4_API ABallPlayer : public APawn
{
	GENERATED_BODY()

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

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

	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Components")
	UStaticMeshComponent* MeshMain;

	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Components")
	USpringArmComponent* SpringArmMain;

	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Components")
	UCameraComponent* CameraMain;

	UPROPERTY(EditAnywhere,BlueprintReadWrite)
	float MoveForce = 500.00f;

	UPROPERTY(EditAnywhere, BlueprintReadWrite)
	float JumpForce = 500.00f;

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

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

	void MoveRight(float value);
	void MoveForward(float value);
	void Jump();
};

我们再来看CPP文件
构造函数中我们看到创建了Mesh，SpringArm和Camera。
SetupAttachment的作用是设置父对象，例如SprintArm的父对象是Mesh。相机是最子层。

SetupPlayerInputComponent函数中绑定了按键，我们后面再截图上来。
BindAction，BindAxis 分别对应了不同的操作。

当键盘按下的时候，就进入（MoveRight，MoveForward，Jump）3个函数进行前后左右跳跃处理。

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


#include "BallPlayer.h"
#include "Camera/CameraComponent.h"
#include "GameFramework/SpringArmComponent.h"


// Sets default values
ABallPlayer::ABallPlayer()
{
 	// Set this pawn to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
	PrimaryActorTick.bCanEverTick = false;
	MeshMain = CreateDefaultSubobject<UStaticMeshComponent>("Mesh");
	SpringArmMain = CreateDefaultSubobject<USpringArmComponent>("SpringArm");
	CameraMain = CreateDefaultSubobject<UCameraComponent>("Camera");

	RootComponent = MeshMain;
	SpringArmMain->SetupAttachment(MeshMain);
	CameraMain->SetupAttachment(SpringArmMain);

	MeshMain->SetSimulatePhysics(true);
	SpringArmMain->bUsePawnControlRotation = true;
}

// Called when the game starts or when spawned
void ABallPlayer::BeginPlay()
{
	Super::BeginPlay();
	MoveForce *= MeshMain->GetMass();
	JumpForce *= MeshMain->GetMass();
}

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

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

	//映射按键
	InputComponent->BindAction("Jump", IE_Pressed, this, &ABallPlayer::Jump);
	InputComponent->BindAxis("MoveForward", this,  &ABallPlayer::MoveForward);
	InputComponent->BindAxis("MoveRight", this,  &ABallPlayer::MoveRight);
}

void ABallPlayer::MoveRight(float value)
{
	const FVector right = CameraMain->GetRightVector() * MoveForce * value;
	MeshMain->AddForce(right);
}

void ABallPlayer::MoveForward(float value)
{
	const FVector forward = CameraMain->GetForwardVector() * MoveForce * value;
	MeshMain->AddForce(forward);
}

void ABallPlayer::Jump()
{
	MeshMain->AddImpulse(FVector(0, 0, JumpForce));
}