Normals come out wrong using VIS (Vtk Integration Service)

Hi,

I'm having quite the issue for some days getting the VIS classes to work my way and would greatly appreciate some directions and/or confirmation that it could be an issue with OCCT.

I'm will try to keep it simple and not post walls of source code.

I'm trying to get out of VIS a list of points, triangles indexes and normals to be use as data for an external renderer.

The two first sets of data come out fine. And as the title suggests, the normals "came out" wrong (see attachment for a screenshot of a VTK window showing theses, base model is a simple cube)

I tried with the code snippets from the guides.

Both the high level API way and the low level one.

I tried while using the low level way to fiddle around with the different parameters from the ShapeMesher

const Standard_Real& theDevCoeff = 0.0001,
const Standard_Real& theDevAngle = 12.0 * M_PI / 180.0,
const Standard_Integer theNbUIsos = 1,
const Standard_Integer theNbVIsos = 

No success ( but granted that I can't barely understand theses, still no result even with extreme values)

Edit: Here goes some simplified code, I hope it will help to provide some insight :)

//Class cpp file (Simplified)

STEPControl_Reader reader;
IFSelect_ReturnStatus stat = reader.ReadFile(path);

if (stat != IFSelect_ReturnStatus::IFSelect_RetDone) {
    std::cout << std::endl << " Failed to load file at path : " << path << std::endl;
    return false;
}
reader.NbRootsForTransfer();
reader.TransferRoots();
lastLoadedShape = reader.OneShape();

IVtkOCC_Shape::Handle aShapeImpl = new IVtkOCC_Shape(lastLoadedShape);
IVtkVTK_ShapeData::Handle aDataImpl = new IVtkVTK_ShapeData();
IVtk_IShapeMesher::Handle aMesher = new IVtkOCC_ShapeMesher(0.0001, 6);

aMesher->Build(aShapeImpl, aDataImpl);

//This is a member of the class
currentStateOfData = aDataImpl->getVtkPolyData();

vtkSmartPointer<vtkPolyDataNormals> normalData = vtkSmartPointer<vtkPolyDataNormals>::New();

normalData->SetInputData(data_source);
normalData->ComputePointNormalsOn();
normalData->ComputeCellNormalsOff();
normalData->Update();

currentStateOfData = normalData->GetOutput();



// Next comes the code that invoke a 'VTk Debug window' (see attachement)

Any idea appreciated !