Hi!

I’m trying to use this article to learn a bit about procedural meshes:

When I add in a 4th vertex so that I can make a simple square, no matter the normal I assign to it, it seems the normal of the new triangle seems to change depending on the sequence that the vertices are connected?

```
TArray<FVector> vertices;
vertices.Add(FVector(0, 0, 0));
vertices.Add(FVector(0, 100, 0));
vertices.Add(FVector(0, 0, 100));
vertices.Add(FVector(0, 100, 100));
TArray<int32> Triangles;
Triangles.Add(0);
Triangles.Add(1);
Triangles.Add(2);
Triangles.Add(1);
Triangles.Add(2);
Triangles.Add(3);
//Triangles.Add(3);
//Triangles.Add(2);
//Triangles.Add(1);
TArray<FVector> normals;
normals.Add(FVector(1, 0, 0));
normals.Add(FVector(1, 0, 0));
normals.Add(FVector(1, 0, 0));
normals.Add(FVector(1, 0, 0));
```

To me it seemed logical that my new triangle needed to be made of the **Triangles** indices: 1,2, then 3. This ended up making a triangle like this picture (spawned two copies of the Actor to show the different triangle normal):

But if I change the order of the **Triangles** indices to be 3,2, then 1 (as in the commented out code) then I get a more correct looking face:

Why is it that the order of adding the indices matters? And how do we work out which way we want in more complex geometry?