Lighing of procedural mesh is glitching

[muller230395]

Hello! I have some strange problems with procedural mesh lighting? What could it be?

Code for generating static maesh:

    TArray<FVector> vertices;
    TArray<int32> triangles;
    vertices.Add(FVector(986.384277f, 924.700989f, 0));
    vertices.Add(FVector(1024.00000, 921.248535, 0));
    vertices.Add(FVector(965.699890, 938.674500, 0));

    triangles.Add(0);
    triangles.Add(1);
    triangles.Add(2);

    TArray<FVector> normals;
    normals.Push(FVector(0, 0, 1));
    normals.Push(FVector(0, 0, 1));
    normals.Push(FVector(0, 0, 1));

    TArray<FProcMeshTangent> tangents;
    TArray<FLinearColor> vertexColors;
    TArray<FVector2D> uvs;

    float LeftestX = std::numeric_limits<float>().infinity();
    float RightestX = -std::numeric_limits<float>().infinity();

    float LowestY = std::numeric_limits<float>().infinity();
    float HighestY = -std::numeric_limits<float>().infinity();

    for (const auto& Vertex : vertices)
    {
        LeftestX = FMath::Min(LeftestX, Vertex.X);
        RightestX = FMath::Max(RightestX, Vertex.X);

        LowestY = FMath::Min(LeftestX, Vertex.Y);
        HighestY = FMath::Max(RightestX, Vertex.Y);
    }

    float DeltaX = RightestX - LeftestX;
    float DeltaY = HighestY - LowestY;

    for (const auto& Vertex : vertices)
    {
        uvs.Add(FVector2D(Vertex.X / DeltaX, Vertex.Y / DeltaY));
    }
    
    LandscapeMesh->CreateMeshSection_LinearColor(0, vertices, triangles, normals, uvs, vertexColors, tangents, true);

[muller230395]

The problem was solved by ordering vertices counter-clockwise

for (int32 Index = 0; Index < vertices.Num(); Index += 3)
    {
        FVector A = vertices[Index];
        FVector B = vertices[Index + 1];
        FVector C = vertices[Index + 2];

        if (FVector::CrossProduct(B - A, C - A).Z < 0)
        {
            triangles.Add(Index);
            triangles.Add(Index + 1);
            triangles.Add(Index + 2);
        }
        else
        {
            triangles.Add(Index);
            triangles.Add(Index + 2);
            triangles.Add(Index + 1);
        }
    }