'Set the (Nf, 3) array of faces. Each rown in the array contains
three indexes into the vertex array, specifying the three corners
of a triangular face.'

def setFaces(self, faces):

    self._faces = faces
    self._edges = None
    self._vertexFaces = None
    self._vertexesIndexedByFaces = None
    self.resetNormals()
    self._vertexColorsIndexedByFaces = None
    self._faceColorsIndexedByFaces = None
