致命错误 LNK2019 C++，Ureal Engine Build

如何解决致命错误 LNK2019 C++，Ureal Engine Build

当我尝试为虚幻引擎 4.26 构建 cpp 代码时出现错误。我正在尝试添加到我的游戏功能中，以确定我玩游戏时的表面类型。这就是我添加 UDeterminSurfaceType 函数的原因。部分代码如下所示：

SurfaceType = UPhysicalMaterial::DetermineSurfaceType(Hit.PhysMaterial.Get());

        UParticleSystem* SelectedEffect = nullptr;
        switch (SurfaceType)
        {
        case SurfaceType1:
            SelectedEffect = FleshImpactEffect;
            break;
        case SurfaceType2:
            SelectedEffect = FleshImpactEffect;
            break;
        default:
            SelectedEffect = DefaultImpactEffect;
            break;
        }


        if (SelectedEffect)
        {
            UGameplayStatics::SpawnEmitterAtLocation(GetWorld(),SelectedEffect,Hit.ImpactPoint,Hit.ImpactNormal.Rotation());
        }

我知道事实尚未完善，我稍后会这样做。添加此行并构建项目后，出现 LNK2019 错误。

  Error LNK2019 unresolved external symbol "__declspec(dllimport) public: static enum 
  EPhysicalSurface __cdecl UPhysicalMaterial::DetermineSurfaceType(class UPhysicalMaterial const *)" 
  (__imp_?DetermineSurfaceType@UPhysicalMaterial@@SA?AW4EPhysicalSurface@@PEBV1@@Z) referenced in 
  function "public: virtual void __cdecl ASWeapon::Fire(void)" (?Fire@ASWeapon@@UEAAXXZ)

此错误意味着，我的 ASWeapon 类头文件中有一个名为“Fire”的方法，但它在您的 SWeapon.CPP 文件中不存在。因此，链接器为您的武器类创建一个 OBJ 文件，然后当它尝试将声明与实现相匹配时，它找不到实现，并且您会收到这个可爱的链接器错误。但是我已经在 CPP 和头文件中都有方法“Fire”。它是在此处创建的：

public: 

UFUNCTION(BlueprintCallable,Category = "Weapon")
virtual void Fire();

这是整个 SWeapon.cpp 代码：

static int32 DebugWeaponsDrawing = 0;
FAutoConsoleVariableRef CVARDebugWeaponDrawing(
TEXT("COOP.DebugWeapons"),DebugWeaponsDrawing,TEXT("Draw Debug Lines for Weapons"),ECVF_Cheat);

// Sets default values
ASWeapon::ASWeapon()
{
MeshComp = CreateDefaultSubobject<USkeletalMeshComponent>(TEXT("MeshComp"));
RootComponent = MeshComp;

MuzzleSocketName = "MuzzleSocket";
TracerTargetName = "Target";
}


void ASWeapon::Fire()
{
// urmarirea mapei din ochii pionului pana la locatia tintei

AActor* MyOwner = GetOwner();
if (MyOwner)
{
    FVector EyeLocation;
    FRotator EyeRotation;
    MyOwner->GetActorEyesViewPoint(EyeLocation,EyeRotation);

    FVector ShotDirection = EyeRotation.Vector();

    FVector TraceEnd = EyeLocation + (ShotDirection * 10000);

    FCollisionQueryParams QueryParams;
    QueryParams.AddIgnoredActor(MyOwner);
    QueryParams.AddIgnoredActor(this);
    QueryParams.bTraceComplex = true;

    // parametrul pentru particulele tintei
    FVector TracerEndPoint = TraceEnd;

    EPhysicalSurface SurfaceType = SurfaceType_Default;

    FHitResult Hit;
    if (GetWorld()->LineTraceSingleByChannel(Hit,EyeLocation,TraceEnd,ECC_Visibility,QueryParams))
    {
        // Blocare lovitura,cauzeaza daune

        AActor* HitActor = Hit.GetActor();

        UGameplayStatics::ApplyPointDamage(HitActor,20.0f,ShotDirection,Hit,MyOwner- 
        >GetInstigatorController(),this,DamageType);

        SurfaceType = UPhysicalMaterial::DetermineSurfaceType(Hit.PhysMaterial.Get());

        UParticleSystem* SelectedEffect = nullptr;
        switch (SurfaceType)
        {
        case SurfaceType1:
            SelectedEffect = FleshImpactEffect;
            break;
        case SurfaceType2:
            SelectedEffect = FleshImpactEffect;
            break;
        default:
            SelectedEffect = DefaultImpactEffect;
            break;
        }


        if (SelectedEffect)
        {
            UGameplayStatics::SpawnEmitterAtLocation(GetWorld(),Hit.ImpactNormal.Rotation());
        }

        TracerEndPoint = Hit.ImpactPoint;

    }

    if (DebugWeaponsDrawing > 0)
    {
        DrawDebugLine(GetWorld(),FColor::White,false,1.0f,1.0f);
    }

    PlayFireEffects(TracerEndPoint);
}

}


void ASWeapon::PlayFireEffects(FVector TraceEnd)
{
if (MuzzleEffect)
{
    UGameplayStatics::SpawnEmitterAttached(MuzzleEffect,MeshComp,MuzzleSocketName);
}

if (TracerEffect)
{
    FVector MuzzleLocation = MeshComp->GetSocketLocation(MuzzleSocketName);

    UParticleSystemComponent* TracerComp = UGameplayStatics::SpawnEmitterAtLocation(GetWorld(),TracerEffect,MuzzleLocation);
    if (TracerComp)
    {
        TracerComp->SetVectorParameter(TracerTargetName,TraceEnd);
    }

}

APawn* MyOwner = Cast<APawn>(GetOwner());
if (MyOwner)
{
    APlayerController* PC = Cast<APlayerController>(MyOwner->GetController());
    if (PC)
    {
        PC->ClientPlayCameraShake(FireCamShake);
    }
}
}

这是标题代码：

class USkeletalMeshComponent;
class UDamageType;
class UParticleSystem;

UCLASS()
class GAME_API ASWeapon : public AActor
{
GENERATED_BODY()

public: 
// Sets default values for this actor's properties
ASWeapon();

protected:

UPROPERTY(VisibleAnywhere,BlueprintReadOnly,Category = "Components")
USkeletalMeshComponent* MeshComp;

void PlayFireEffects(FVector TraceEnd);

UPROPERTY(EditDefaultsOnly,Category = "Weapon")
TSubclassOf<UDamageType> DamageType;

UPROPERTY(VisibleDefaultsOnly,Category = "Weapon")
FName MuzzleSocketName;

UPROPERTY(VisibleDefaultsOnly,Category = "Weapon")
FName TracerTargetName;

UPROPERTY(EditDefaultsOnly,Category = "Weapon")
UParticleSystem* MuzzleEffect;

UPROPERTY(EditDefaultsOnly,Category = "Weapon")
UParticleSystem* DefaultImpactEffect;

UPROPERTY(EditDefaultsOnly,Category = "Weapon")
UParticleSystem* FleshImpactEffect;

UPROPERTY(EditDefaultsOnly,Category = "Weapon")
UParticleSystem* TracerEffect;

UPROPERTY(EditDefaultsOnly,Category = "Weapon")
TSubclassOf<UCameraShakeBase> FireCamShake;


public: 

UFUNCTION(BlueprintCallable,Category = "Weapon")
virtual void Fire();
};

在添加表面类型检测器之前，其余代码运行良好。如果您知道如何解决此问题，我将不胜感激。

解决方法

我发现了问题。在 UE4.26 中，为 Physic Core 添加了一个新功能作为模块依赖项。我必须将此核心添加到 Game(your game name).build.cs 。 那是一行：

PublicDependencyModuleNames.AddRange(new string[] { "Core","CoreUObject","Engine","InputCore","PhysicsCore" });