UE 使用 UCustomMeshComponent 绘制圆

UCustomMeshComponent 只能支持简单的自定mesh，这种Mesh并不支持贴图材质。官方的API也只有简单的三个函数而已。

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ACustomSphereActor 是我自定义的辅助Actor

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

#pragma once

#include "CoreMinimal.h"
#include "CustomMeshComponent.h"
#include "GameFramework/Actor.h"

#include "Materials/Material.h"

#include "CustomPanelActor.generated.h"

UCLASS()
class CUSTOMLINEPLUGINS_API ACustomPanelActor : public AActor
{
    GENERATED_BODY()
    
public: 
    // Sets default values for this actor's properties
    ACustomPanelActor();

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

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

public:
    UPROPERTY(VisibleAnywhere)
    UCustomMeshComponent* MeshComponent;

    UPROPERTY(EditAnywhere,BlueprintReadOnly,Category = "Custom")
    UMaterial* Material;

    UPROPERTY(EditAnywhere,BlueprintReadOnly,Category = "Custom")
    FVector ReocrdPos;
public:
    
    UFUNCTION(BlueprintCallable, Category = "Custom")
    void Create();
    UFUNCTION(BlueprintCallable, Category = "Custom")
    void Update(float Len);
    UFUNCTION(BlueprintCallable, Category = "Custom")
    void CreateSmallSphere(FVector Location,FString Name,float Scale);
    
private:
    int num=180;
    TArray<FVector>  Points;
    TArray<FCustomMeshTriangle> Meshvertices;
};

#include "CustomPanelActor.h"
#include "CustomMeshPanelActor.h"
#include "CustomSphereActor.h"

// Sets default values
ACustomPanelActor::ACustomPanelActor()
{
    // 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;
    MeshComponent = CreateDefaultSubobject<UCustomMeshComponent>(TEXT("CustomMeshComponentZ"));
}

// Called when the game starts or when spawned
void ACustomPanelActor::BeginPlay()
{
    Super::BeginPlay();
    ReocrdPos=GetActorLocation();
    Create();
}

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

void ACustomPanelActor::Create()
{
    float angle = 360.0f / num;
    FVector dir = FVector::Zero();
    FVector forward = FVector::ForwardVector;

    Points.Add(ReocrdPos);
    //CreateSmallSphere(ReocrdPos,"AA_"+FString::FromInt(0),0.2f);
    for (int i = 1; i < num+1; i++)
    {
        FVector vec = FVector(0,0,angle * i);
        FQuat rot=FQuat::MakeFromEuler(vec);
        dir = rot * forward;
        Points.Add(ReocrdPos+dir);

       // CreateSmallSphere(ReocrdPos+dir,"AA_"+FString::FromInt(i),0.2f);
    }
    
     for (int i = 0; i < num; i++)
    {
        FCustomMeshTriangle temp;
        temp.Vertex0 = Points[num-1==i?1:2+i];
        temp.Vertex1 = Points[num-1==i?i:1+i];
        temp.Vertex2 = Points[0];
        Meshvertices.Add(temp);
    }
    MeshComponent->AddCustomMeshTriangles(Meshvertices);
    
    if(Material!=NULL)
    {
        UMaterialInterface* InterfacePtr = reinterpret_cast<UMaterialInterface*>(Material);
        MeshComponent->SetMaterial(0,InterfacePtr);
    }
}

void ACustomPanelActor::Update(float Len)
{
    float angle = 360.0f / num;
    FVector dir = FVector::Zero();
    FVector forward = FVector::ForwardVector;

    Points[0]=ReocrdPos;
    for (int i = 1; i < num+1; i++)
    {
        FVector vec = FVector(0,0,angle * i);
        FQuat rot=FQuat::MakeFromEuler(vec);
        dir = rot * forward*Len;
        Points[i]=(ReocrdPos+dir);
    }
    
    for (int i = 0; i < num; i++)
    {
        FCustomMeshTriangle temp;
        temp.Vertex0 = Points[num-1==i?1:2+i];
        temp.Vertex1 = Points[num-1==i?i:1+i];
        temp.Vertex2 = Points[0];
        Meshvertices[i]=temp;
    }
    MeshComponent->SetCustomMeshTriangles(Meshvertices);
}


void ACustomPanelActor::CreateSmallSphere(FVector Location,FString Name,float Scale=0.3f)
{
    Location=ReocrdPos+Location;
    ACustomSphereActor* Temp=GetWorld()->SpawnActor<ACustomSphereActor>(ACustomSphereActor::StaticClass(),Location, FRotator(0.0f));
    Temp->SetActorScale3D(FVector(Scale,Scale,Scale));
    Temp->SetActorLabel(Name);
    //#if WITH_EDITOR 
    //ACustomSphereActor* temp = GetWorld()->SpawnActor<ACustomSphereActor>(ACustomSphereActor::StaticClass(), Location, FRotator(0.f));
    //  ACustomSphereActor* Temp = GetWorld()->SpawnActor<ACustomSphereActor>(Location, FRotator(0.f));
    //#endif
}