func cellIdsToJSON(w http.ResponseWriter, ids []s2.CellID) {
covering := []CellIDJSON{}
for _, id := range ids {
idJson := CellIDJSON{}
cell := s2.CellFromCellID(id)
center := s2.LatLngFromPoint(cell.Center())
for i := 0; i < 4; i++ {
ll := s2.LatLngFromPoint(cell.Vertex(i))
idJson.Shape[i].Lat = ll.Lat.Degrees()
idJson.Shape[i].Lng = ll.Lng.Degrees()
}
idJson.LL.Lat = center.Lat.Degrees()
idJson.LL.Lng = center.Lng.Degrees()
idJson.Id = strconv.FormatUint(uint64(cell.Id()), 10)
idJson.IdSigned = strconv.FormatInt(int64(cell.Id()), 10)
idJson.Token = cell.Id().ToToken()
idJson.Pos = strconv.FormatUint(cell.Id().Pos(), 10)
idJson.Face = cell.Id().Face()
idJson.Level = cell.Id().Level()
covering = append(covering, idJson)
}
enc := json.NewEncoder(w)
if err := enc.Encode(covering); err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
}
}
func s2PolygonToGeometry(poly s2.Polygon) *geojson.Polygon {
// Don't want nil rings for coordinates.
rings := [][]geojson.Coordinate{}
for i := 0; i < poly.NumLoops(); i++ {
loop := poly.Loop(i)
var ring []geojson.Coordinate
for j := 0; j <= loop.NumVertices(); j++ {
ll := s2.LatLngFromPoint(*loop.Vertex(j))
ring = append(ring, geojson.Coordinate{ll.Lng.Degrees(), ll.Lat.Degrees()})
}
rings = append(rings, ring)
}
return &geojson.Polygon{Typ: "Polygon", Coordinates: rings}
}