UE5.3 C++ USTRUCT的规范使用和制作简单的画线插件

一.创造一个USTRUCT

1.首先需要创建一个，None。

#include "LineDataStruct.generated.h"

FTPAData里加入GENERATED_USTRUCT_BODY();

 //Topic=DDS_TPA_Data, 预测航迹线，单次事件
USTRUCT()
struct FTPAData
{GENERATED_USTRUCT_BODY();int16 header;                              // 包头int16 flag;                                // 标志位int64 timestamp;                           // 时间戳int16 validPointCount;                     // 轨迹有效点数  最大值1000，轨迹有效点数为N1时读取N1个轨迹点数据int16 reserved1;                           // 预留接口1int16 reserved2;                           // 预留接口2int16 reserved3;                           // 预留接口3int32 reserved4;                           // 预留接口4int32 reserved5;                           // 预留接口5FTPAData_Point TPAData_Point[1000];	// 轨迹点数组int16 checksum;                            // 校验值
};#pragma pack()

如果想让蓝图认识，需要加BlueprintType。如果想让变量能在蓝图中访问,可用Break/Make，需要使用UPROPERTY修饰符(BlueprintReadWrite)。

二.画线插件

不多废话，直接上代码

UCLASS()
class HMSLINESYSTEM_API UDrawLineSubsystem : public UGameInstanceSubsystem
{GENERATED_BODY()
public:void UpdateLinePath(int id,FVector First,FVector Second);//void UpdateLinePath2(int id,FVector First, FVector Second);//void LinePatch(FVector Fi);
private:void InitialGeoreference();
public:
private:ACesiumGeoreference* Georeference;//航迹线，航迹线idTMap<int8, ASplineActor*> LinePathMap;TMap<int8, ALinePatchActor*> LinePatchPathMap;UMaterialParameterCollectionInstance* M_ParamCollection;int num = 100.f;};

先介绍，这种简单一点的通过，UE自带的LinePatchComponent进行画线，给一头一尾就能画。将Cesium的点换为UE坐标系的点，再去画。

//void UpdateLinePath2(int id,FVector First, FVector Second);
void UDrawLineSubsystem::UpdateLinePath2(int id, FVector First, FVector Second)
{int32 tmpPathID = id;if (LinePatchPathMap.Find(tmpPathID)){if (!Georeference)InitialGeoreference();if (!Georeference) return;if (!First.IsZero()){//处理点位信息FVector tmpDataPosition = FVector(First);FVector FirstUELocation = Georeference->TransformLongitudeLatitudeHeightPositionToUnreal(tmpDataPosition);LinePatchPathMap[tmpPathID]->SetActorLocation(FirstUELocation);First = FirstUELocation;}if (!Second.IsZero()){//处理点位信息FVector tmpDataPosition = FVector(Second);FVector SecondUELocation = Georeference->TransformLongitudeLatitudeHeightPositionToUnreal(tmpDataPosition);Second = SecondUELocation;}LinePatchPathMap[tmpPathID]->CreateLine(First, Second);//M_ParamCollection->SetScalarParameterValue(FName("CollisionHeightLow"), CollisionRender.HightLow * 100.f);}else{ALinePatchActor* LinePatchActor = GetWorld()->SpawnActor<ALinePatchActor>();if (!LinePatchActor){UE_LOG(LogTemp, Error, TEXT("failed to spawn LinePathActor! UDrawLineSubsystem::UpdateLinePath2"));return;}else{LinePatchPathMap.Add(tmpPathID, LinePatchActor);}}
}

这个是画线的，把头和组件加上就行了。

#include "Components/LineBatchComponent.h"

// Sets default values
ALinePatchActor::ALinePatchActor()
{// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.PrimaryActorTick.bCanEverTick = true;SetRootComponent(CreateDefaultSubobject<USceneComponent>(TEXT("DefaultSceneRoot")));LineBatchComponent = CreateDefaultSubobject<ULineBatchComponent>(TEXT("LineBatchComponent"));LineBatchComponent->SetupAttachment(RootComponent);
}

void ALinePatchActor::CreateLine(FVector First, FVector Second)
{LineBatchComponent->Flush();LineBatchComponent->DrawLine(First, Second, FColor::Purple, 1.f, 50.f, 0); // Adjust the colors and thickness as needed
}

用UGameInstanceSubsystem做插件的好处，有很多。自己能管理生命周期，获取方便。

把模块和头加上就能从GameInstance里获得GameSubsystem,再转换为自己的system。

UDrawLineSubsystem* LineSystem = GetWorld()->GetGameInstance()->GetSubsystem<UDrawLineSubsystem>();