使用UProceduralMeshComponent可以自由的用三角星来绘制三维图形

1. 在actor的构造函数中添加UProceduralMeshComponent组件

mesh = CreateDefaultSubobject<UProceduralMeshComponent>(TEXT("mesh"));
Material = LoadObject<UMaterial>(NULL, TEXT("/Game/VertexColorMaterial"), NULL, LOAD_None, NULL);

2. 绘制矩形

void AMyActor::MeshDrawRect(FVector2D Position, FVector2D Size, FLinearColor color)
{TArray<FVector> vertices;vertices.Add(FVector(0, Position.X, Position.Y));vertices.Add(FVector(0, Position.X + Size.X, Position.Y));vertices.Add(FVector(0, Position.X + Size.X, Position.Y + Size.Y));vertices.Add(FVector(0, Position.X, Position.Y));vertices.Add(FVector(0, Position.X + Size.X, Position.Y + Size.Y));vertices.Add(FVector(0, Position.X, Position.Y + Size.Y));TArray<int32> Triangles;for (int i = 0; i < vertices.Num(); i++){ Triangles.Add(i);}TArray<FLinearColor> vertexColors;for (int i = 0; i < vertices.Num(); i++){vertexColors.Add(color);}if (m_bIsRotate){mesh->CreateMeshSection_LinearColor(m_nIndex, MeshRotation(vertices, m_centerRotate, m_degreeRotate), Triangles, normals, UV0, vertexColors, tangents, true);}else{mesh->CreateMeshSection_LinearColor(m_nIndex, vertices, Triangles, normals, UV0, vertexColors, tangents, true);}mesh->SetMaterial(m_nIndex++, Material);
}

3. 绘制圆形

void AMyActor::MeshDrawCircle(FVector2D center, int radius, int NumSegments, FLinearColor color)
{if (NumSegments == 0)NumSegments = 360.0;float SegmentLength = 360.0 / NumSegments;TArray<FVector> vertices;for (float i = 0; i < 360.0; i += SegmentLength){FVector2D PositionA(cos(i * PI / 180.0) * radius + center.X, sin(i * PI / 180.0) * radius + center.Y);FVector2D PositionB(cos((i + SegmentLength) * PI / 180.0) * radius + center.X, sin((i + SegmentLength) * PI / 180.0) * radius + center.Y);vertices.Add(FVector(0, center.X, center.Y));vertices.Add(FVector(0, PositionA.X, PositionA.Y));vertices.Add(FVector(0, PositionB.X, PositionB.Y));}TArray<int32> Triangles;for (int i = 0; i < vertices.Num(); i++){Triangles.Add(i);}TArray<FLinearColor> vertexColors;for (int i = 0; i < vertices.Num(); i++){vertexColors.Add(color);}mesh->CreateMeshSection_LinearColor(m_nIndex, vertices, Triangles, normals, UV0, vertexColors, tangents, true);mesh->SetMaterial(m_nIndex++, Material);
}