private static void AddPolylineWithLabels(S2Polyline polyline, EdgeType edge_type,
Int32 label_begin, S2Builder builder, EdgeLabelMap edge_label_map)
{
for (int i = 0; i + 1 < polyline.NumVertices(); ++i)
{
Int32 label = label_begin + i;
builder.SetLabel(label);
// With undirected edges, reverse the direction of every other input edge.
int dir = edge_type == EdgeType.DIRECTED ? 1 : (i & 1);
builder.AddEdge(polyline.Vertex(i + (1 - dir)), polyline.Vertex(i + dir));
S2Point key = polyline.Vertex(i) + polyline.Vertex(i + 1);
edge_label_map[key].Add(label);
}
}
private static void AddShapeWithLabels(S2Shape shape, EdgeType edge_type,
S2Builder builder, EdgeLabelMap edge_label_map)
{
const int kLabelBegin = 1234; // Arbitrary.
for (int e = 0; e < shape.NumEdges(); ++e)
{
Int32 label = kLabelBegin + e;
builder.SetLabel(label);
// For undirected edges, reverse the direction of every other input edge.
S2Shape.Edge edge = shape.GetEdge(e);
if (edge_type == EdgeType.UNDIRECTED && ((e & 1) != 0))
{
edge = new S2Shape.Edge(edge.V1, edge.V0);
}
builder.AddEdge(edge.V0, edge.V1);
edge_label_map[GetKey(edge, edge_type)].Add(label);
}
}
private static void AddPoint(S2Point p, S2Builder builder)
{
builder.AddEdge(p, p);
}