Intentando arreglar las normales de malla 3D

I have triangle collection that define mesh surface of my 3D shape, I would like to fix normal of each triangle to point outshape.

I was trying the following (pseudo):

1. define that first triangle normal direction is right direction
2. go over the mesh using kind of DFS like this:
3. triangle = first triangle
4. foreach neigbour in triangle.getNeighbours
5. if angle between neighbor and triangle greater then 180 do neighbor.flip()
6. triangle = neighbor
7. if neighbor already picked then continue to next neighbor
8. continue recursively to 4.

But step 5 in algorithm does not work because cant know if the angle is greater then 180, because i need to know in witch direction (clockwise or counter clockwise).

There is no need to calculate angle between neighbours. If triangle `ABC` is oriented (`A->B->C`), and if neighbour on edge `AB` is triangle `ABD`, than it has to have opposite orientation on edge `AB`. That means, neigbouring triangle has to be orientated `B->A->D`.