Take each key (ie. point) in the graph and for that point
        create an edge to every point downstream of it where the weight
        of the edge is the tuple (distance, angle)

def CreateDirectedEdges(self, points, gr, layer_width):
        """
        Take each key (ie. point) in the graph and for that point
        create an edge to every point downstream of it where the weight
        of the edge is the tuple (distance, angle)
        """
        for z0, x0, Q0 in points:
            for z1, x1, Q1 in points:
                dz = z1 - z0  # no fabs because we check arrow direction
                if dz > 0.0:  # make sure arrow in right direction
                    if dz - layer_width < distance_threshold:  # only adjacents
                        dx = math.fabs(x1 - x0)

                        if dx > 5 * bar_width:
                            continue

                        # Weights are negative to in order to use shortest path
                        # algorithms on the graph.
                        weight = -1 * math.hypot(dz, dx)

                        edge = ((z0, x0, Q0), (z1, x1, Q1))

                        gr.add_edge(edge, wt=weight)

        # Ensure that it is already transitively reduced
        assert len(critical.transitive_edges(gr)) == 0

        return gr