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5.在编辑器中运行

  1. 虚幻编辑器 中,按下 Compile 按钮即可加载代码修改。

    CompileFromEditor.png

  2. 需要将 CollidingPawn 的一个实例放入世界场景。类保存在 内容浏览器“C++ Classes/HowTo_Components/CollidingPawn”路径下。

    ClassInContentBrowser.png

    LevelEditorBeforePlay.png

  3. 按下 Play 按钮后,使用 WASD 键移动球体,使用鼠标转向,与场景中的对象(如此例中的桌子或椅子,或放置在场景中的其他物理对象)发生碰撞和滑动。按下空格键还可以在球体上生成火焰(或消除已生成的火焰)!

    CollidingAndOnFire.png


虚幻引擎 4 中有各种类型的 组件 - 我们此处对常见组件的仅仅是停留在表面而已。尝试探索内置的组件或自行编写吧!它们灵活且功能强大,有助于使项目代码整洁有序,便于重复使用。

完成代码

CollidingPawn.h

// 版权所有 1998-2017 Epic Games, Inc. 保留所有权利。

#pragma once

#include "GameFramework/Pawn.h"
#include "CollidingPawn.generated.h"

UCLASS()
class HOWTO_COMPONENTS_API ACollidingPawn : public APawn
{
    GENERATED_BODY()

public:
    // 设置该 pawn 属性的默认值
    ACollidingPawn();

    // 游戏开始时或生成时调用
    virtual void BeginPlay() override;

    // 每帧调用
    virtual void Tick( float DeltaSeconds ) override;

    // 调用后将功能绑定到输入
    virtual void SetupPlayerInputComponent(class UInputComponent* InputComponent) override;

    UParticleSystemComponent* OurParticleSystem;
    class UCollidingPawnMovementComponent* OurMovementComponent;

    virtual UPawnMovementComponent* GetMovementComponent() const override;

    void MoveForward(float AxisValue);
    void MoveRight(float AxisValue);
    void Turn(float AxisValue);
    void ParticleToggle();
};

CollidingPawn.cpp

// 版权所有 1998-2017 Epic Games, Inc. 保留所有权利。

#include "HowTo_Components.h"
#include "CollidingPawn.h"
#include "CollidingPawnMovementComponent.h"

// 设置默认值
ACollidingPawn::ACollidingPawn()
{
    // 将此 pawn 设为每帧调用 Tick()。不需要时可将此关闭,以提高性能。
    PrimaryActorTick.bCanEverTick = true;

    // 我们的根组件是对物理作出反应的球体
    USphereComponent* SphereComponent = CreateDefaultSubobject<USphereComponent>(TEXT("RootComponent"));
    RootComponent = SphereComponent;
    SphereComponent->InitSphereRadius(40.0f);
    SphereComponent->SetCollisionProfileName(TEXT("Pawn"));

    // 创建并放置一个网格体组件,以便了解球体的所在位置
    UStaticMeshComponent* SphereVisual = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("VisualRepresentation"));
    SphereVisual->AttachTo(RootComponent);
    static ConstructorHelpers::FObjectFinder<UStaticMesh> SphereVisualAsset(TEXT("/Game/StarterContent/Shapes/Shape_Sphere.Shape_Sphere"));
    if (SphereVisualAsset.Succeeded())
    {
        SphereVisual->SetStaticMesh(SphereVisualAsset.Object);
        SphereVisual->SetRelativeLocation(FVector(0.0f, 0.0f, -40.0f));
        SphereVisual->SetWorldScale3D(FVector(0.8f));
    }

    // 创建一个可启用或停用的粒子系统
    OurParticleSystem = CreateDefaultSubobject<UParticleSystemComponent>(TEXT("MovementParticles"));
    OurParticleSystem->AttachTo(SphereVisual);
    OurParticleSystem->bAutoActivate = false;
    OurParticleSystem->SetRelativeLocation(FVector(-20.0f, 0.0f, 20.0f));
    static ConstructorHelpers::FObjectFinder<UParticleSystem> ParticleAsset(TEXT("/Game/StarterContent/Particles/P_Fire.P_Fire"));
    if (ParticleAsset.Succeeded())
    {
        OurParticleSystem->SetTemplate(ParticleAsset.Object);
    }

    // 使用弹簧臂让摄像机运动平稳而自然。
    USpringArmComponent* SpringArm = CreateDefaultSubobject<USpringArmComponent>(TEXT("CameraAttachmentArm"));
    SpringArm->AttachTo(RootComponent);
    SpringArm->RelativeRotation = FRotator(-45.f, 0.f, 0.f);
    SpringArm->TargetArmLength = 400.0f;
    SpringArm->bEnableCameraLag = true;
    SpringArm->CameraLagSpeed = 3.0f;

    // 创建一个摄像机,将其附着到弹簧臂
    UCameraComponent* Camera = CreateDefaultSubobject<UCameraComponent>(TEXT("ActualCamera"));
    Camera->AttachTo(SpringArm, USpringArmComponent::SocketName);

    // 掌控默认玩家
    AutoPossessPlayer = EAutoReceiveInput::Player0;

    // 创建移动组件的一个实例,并告知其更新根组件。
    OurMovementComponent = CreateDefaultSubobject<UCollidingPawnMovementComponent>(TEXT("CustomMovementComponent"));
    OurMovementComponent->UpdatedComponent = RootComponent;
}

// 游戏开始时或生成时调用
void ACollidingPawn::BeginPlay()
{
    Super::BeginPlay();

}

// 每帧调用
void ACollidingPawn::Tick( float DeltaTime )
{
    Super::Tick( DeltaTime );

}

// 调用后将功能绑定到输入
void ACollidingPawn::SetupPlayerInputComponent(class UInputComponent* InputComponent)
{
    Super::SetupPlayerInputComponent(InputComponent);

    InputComponent->BindAction("ParticleToggle", IE_Pressed, this, &ACollidingPawn::ParticleToggle);

    InputComponent->BindAxis("MoveForward", this, &ACollidingPawn::MoveForward);
    InputComponent->BindAxis("MoveRight", this, &ACollidingPawn::MoveRight);
    InputComponent->BindAxis("Turn", this, &ACollidingPawn::Turn);
}

UPawnMovementComponent* ACollidingPawn::GetMovementComponent() const
{
    return OurMovementComponent;
}

void ACollidingPawn::MoveForward(float AxisValue)
{
    if (OurMovementComponent && (OurMovementComponent->UpdatedComponent == RootComponent))
    {
        OurMovementComponent->AddInputVector(GetActorForwardVector() * AxisValue);
    }
}

void ACollidingPawn::MoveRight(float AxisValue)
{
    if (OurMovementComponent && (OurMovementComponent->UpdatedComponent == RootComponent))
    {
        OurMovementComponent->AddInputVector(GetActorRightVector() * AxisValue);
    }
}

void ACollidingPawn::Turn(float AxisValue)
{
    FRotator NewRotation = GetActorRotation();
    NewRotation.Yaw += AxisValue;
    SetActorRotation(NewRotation);
}

void ACollidingPawn::ParticleToggle()
{
    if (OurParticleSystem && OurParticleSystem->Template)
    {
        OurParticleSystem->ToggleActive();
    }
}

CollidingPawnMovementComponent.h

// 版权所有 1998-2017 Epic Games, Inc. 保留所有权利。

#pragma once

#include "GameFramework/PawnMovementComponent.h"
#include "CollidingPawnMovementComponent.generated.h"

/**
 * 
 */
UCLASS()
class HOWTO_COMPONENTS_API UCollidingPawnMovementComponent : public UPawnMovementComponent
{
    GENERATED_BODY()

public:
    virtual void TickComponent(float DeltaTime, enum ELevelTick TickType, FActorComponentTickFunction *ThisTickFunction) override;  
};

CollidingPawnMovementComponent.cpp

// 版权所有 1998-2017 Epic Games, Inc. 保留所有权利。

#include "HowTo_Components.h"
#include "CollidingPawnMovementComponent.h"

void UCollidingPawnMovementComponent::TickComponent(float DeltaTime, enum ELevelTick TickType, FActorComponentTickFunction *ThisTickFunction)
{
    Super::TickComponent(DeltaTime, TickType, ThisTickFunction);

    // 确保所有内容仍然有效,并允许移动。
    if (!PawnOwner || !UpdatedComponent || ShouldSkipUpdate(DeltaTime))
    {
        return;
    }

    // 获取(然后清除)在 ACollidingPawn::Tick 设置的移动矢量。
    FVector DesiredMovementThisFrame = ConsumeInputVector().GetClampedToMaxSize(1.0f) * DeltaTime * 150.0f;
    if (!DesiredMovementThisFrame.IsNearlyZero())
    {
        FHitResult Hit;
        SafeMoveUpdatedComponent(DesiredMovementThisFrame, UpdatedComponent->GetComponentRotation(), true, Hit);

        // 如碰到物体,尝试沿其滑动
        if (Hit.IsValidBlockingHit())
        {
            SlideAlongSurface(DesiredMovementThisFrame, 1.f - Hit.Time, Hit.Normal, Hit);
        }
    }
};