参考：
https://docs.unrealengine.com/zh-CN/Programming/Tutorials/PlayerCamera/index.html
备注：
官方的例子直接拷贝代码，运行不过，需要稍微修改一下。
先上代码，再介绍一下步骤
.h文件
// Fill out your copyright notice in the Description page of Project Settings.
#pragma once
#include "CoreMinimal.h"
#include "GameFramework/Pawn.h"
#include "GameFramework/SpringArmComponent.h"
#include "Camera/CameraComponent.h"
#include "PawnWithCamera.generated.h"
UCLASS()
class PLUGINS_ME_API APawnWithCamera : public APawn
{
GENERATED_BODY()
public:
// Sets default values for this pawn's properties
APawnWithCamera();
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;
protected:
UPROPERTY(EditAnywhere)
USpringArmComponent* OurCameraSpringArm;
UCameraComponent* OurCamera;
//输入变量
FVector2D MovementInput;
FVector2D CameraInput;
float ZoomFactor;
bool bZoomingIn;
//输入函数
void MoveForward(float AxisValue);
void MoveRight(float AxisValue);
void PitchCamera(float AxisValue);
void YawCamera(float AxisValue);
void ZoomIn();
void ZoomOut();
};
.cpp文件
// Fill out your copyright notice in the Description page of Project Settings.
#include "PawnWithCamera.h"
// Sets default values
APawnWithCamera::APawnWithCamera()
{
// 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;
//创建组件
RootComponent = CreateDefaultSubobject<USceneComponent>(TEXT("RootComponent"));
OurCameraSpringArm = CreateDefaultSubobject<USpringArmComponent>(TEXT("CameraSpringArm"));
OurCameraSpringArm->SetupAttachment(RootComponent);
OurCameraSpringArm->SetRelativeLocationAndRotation(FVector(0.0f, 0.0f, 50.0f), FRotator(-60.0f, 0.0f, 0.0f));
OurCameraSpringArm->TargetArmLength = 400.f;
OurCameraSpringArm->bEnableCameraLag = true;
OurCameraSpringArm->CameraLagSpeed = 3.0f;
OurCamera = CreateDefaultSubobject<UCameraComponent>(TEXT("GameCamera"));
OurCamera->SetupAttachment(OurCameraSpringArm, USpringArmComponent::SocketName);
//控制默认玩家
AutoPossessPlayer = EAutoReceiveInput::Player0;
}
// Called when the game starts or when spawned
void APawnWithCamera::BeginPlay()
{
Super::BeginPlay();
}
// Called every frame
void APawnWithCamera::Tick(float DeltaTime)
{
Super::Tick(DeltaTime);
//按下ZoomIn按钮时放大，松开时恢复
{
if (bZoomingIn)
{
ZoomFactor += DeltaTime / 0.5f; //Zoom in over half a second
}
else
{
ZoomFactor -= DeltaTime / 0.25f; //缩小四分之一秒
}
ZoomFactor = FMath::Clamp<float>(ZoomFactor, 0.0f, 1.0f);
//基于ZoomFactor混合相机的FOV和SpringArm长度
OurCamera->FieldOfView = FMath::Lerp<float>(90.0f, 60.0f, ZoomFactor);
OurCameraSpringArm->TargetArmLength = FMath::Lerp<float>(400.0f, 300.0f, ZoomFactor);
}
//旋转Actor的Yaw，由于已与其附加，因此将转动相机
{
FRotator NewRotation = GetActorRotation();
NewRotation.Yaw += CameraInput.X;
SetActorRotation(NewRotation);
}
//旋转相机的Pitch，但进行限制，因此视觉固定朝下
{
FRotator NewRotation = OurCameraSpringArm->GetComponentRotation();
NewRotation.Pitch = FMath::Clamp(NewRotation.Pitch + CameraInput.Y, -80.0f, -15.0f);
OurCameraSpringArm->SetWorldRotation(NewRotation);
}
//根据"MoveX"和"MoveY"轴处理移动
{
if (!MovementInput.IsZero())
{
//以100单位/秒缩放移动输入轴值
MovementInput = MovementInput.GetSafeNormal() * 100.0f;
FVector NewLocation = GetActorLocation();
NewLocation += GetActorForwardVector() * MovementInput.X * DeltaTime;
NewLocation += GetActorRightVector() * MovementInput.Y * DeltaTime;
SetActorLocation(NewLocation);
}
}
}
// 调用以将功能与输入绑定
void APawnWithCamera::SetupPlayerInputComponent(class UInputComponent* PlayerInputComponent)
{
Super::SetupPlayerInputComponent(PlayerInputComponent);
//连接"ZoomIn"的事件
PlayerInputComponent->BindAction("ZoomIn", IE_Pressed, this, &APawnWithCamera::ZoomIn);
PlayerInputComponent->BindAction("ZoomIn", IE_Released, this, &APawnWithCamera::ZoomOut);
//连接四个轴的逐帧处理
PlayerInputComponent->BindAxis("MoveForward", this, &APawnWithCamera::MoveForward);
PlayerInputComponent->BindAxis("MoveRight", this, &APawnWithCamera::MoveRight);
PlayerInputComponent->BindAxis("CameraPitch", this, &APawnWithCamera::PitchCamera);
PlayerInputComponent->BindAxis("CameraYaw", this, &APawnWithCamera::YawCamera);
}
//输入函数
void APawnWithCamera::MoveForward(float AxisValue)
{
if (0.0f != AxisValue)
{
GEngine->AddOnScreenDebugMessage(-1, 0.5, FColor::Blue, "MoveForward AxisValue:" + FString::SanitizeFloat(AxisValue));
}
MovementInput.X = FMath::Clamp<float>(AxisValue, -1.0f, 1.0f);
}
void APawnWithCamera::MoveRight(float AxisValue)
{
MovementInput.Y = FMath::Clamp<float>(AxisValue, -1.0f, 1.0f);
}
void APawnWithCamera::PitchCamera(float AxisValue)
{
if (0.0f != AxisValue)
{
GEngine->AddOnScreenDebugMessage(-1, 0.5, FColor::Blue, "MoveForward PitchCamera:" + FString::SanitizeFloat(AxisValue));
}
CameraInput.Y = AxisValue;
}
void APawnWithCamera::YawCamera(float AxisValue)
{
if (0.0f != AxisValue)
{
GEngine->AddOnScreenDebugMessage(-1, 0.5, FColor::Blue, "MoveForward YawCamera:" + FString::SanitizeFloat(AxisValue));
}
CameraInput.X = AxisValue;
}
void APawnWithCamera::ZoomIn()
{
bZoomingIn = true;
}
void APawnWithCamera::ZoomOut()
{
bZoomingIn = false;
}
重点解读：
按键映射：
相机的移动操作都是在tick里面进行业务逻辑
关键代码解释一下：
ZoomFactor = FMath::Clamp<float>(ZoomFactor, 0.0f, 1.0f); 控制ZoomFactor的值在0.0到1.0之间
OurCamera->FieldOfView = FMath::Lerp<float>(90.0f, 60.0f, ZoomFactor); 60--90之间的线性差值，相当于摄像机的镜头拉近拉远
OurCameraSpringArm->TargetArmLength = FMath::Lerp<float>(400.0f, 300.0f, ZoomFactor); 弹簧拉近拉远
MovementInput.GetSafeNormal()：获取角色运动的方向，单位为1
初始化的函数在解释一下
//创建组件
RootComponent = CreateDefaultSubobject<USceneComponent>(TEXT("RootComponent"));
OurCameraSpringArm = CreateDefaultSubobject<USpringArmComponent>(TEXT("CameraSpringArm"));
OurCameraSpringArm->SetupAttachment(RootComponent);
OurCameraSpringArm->SetRelativeLocationAndRotation(FVector(0.0f, 0.0f, 50.0f), FRotator(-60.0f, 0.0f, 0.0f));
OurCameraSpringArm->TargetArmLength = 400.f;
OurCameraSpringArm->bEnableCameraLag = true;
OurCameraSpringArm->CameraLagSpeed = 3.0f;
OurCamera = CreateDefaultSubobject<UCameraComponent>(TEXT("GameCamera"));
OurCamera->SetupAttachment(OurCameraSpringArm, USpringArmComponent::SocketName);
//控制默认玩家
AutoPossessPlayer = EAutoReceiveInput::Player0;画个流程图：
根节点组件包含弹簧节点组件再包含摄像机节点组件。
最后使用的时候，记得把Pawn拖动进蓝图里面
在这里调整初始化的位置：
