protected static boolean isServiceVisible(DrawContext dc, PlaceNameService placeNameService) {
    //noinspection SimplifiableIfStatement
    if (!placeNameService.isEnabled()) return false;

    return (dc.getVisibleSector() != null)
        && placeNameService.getMaskingSector().intersects(dc.getVisibleSector());
    //
    //        return
    // placeNameService.getExtent(dc).intersects(dc.getView().getFrustumInModelCoordinates());
  }
  protected static boolean isNameVisible(
      DrawContext dc, PlaceNameService service, Position namePosition) {
    double elevation = dc.getVerticalExaggeration() * namePosition.getElevation();
    Vec4 namePoint =
        dc.getGlobe()
            .computePointFromPosition(
                namePosition.getLatitude(), namePosition.getLongitude(), elevation);
    Vec4 eyeVec = dc.getView().getEyePoint();

    double dist = eyeVec.distanceTo3(namePoint);
    return dist >= service.getMinDisplayDistance() && dist <= service.getMaxDisplayDistance();
  }
  protected Tile[] buildTiles(PlaceNameService placeNameService, NavigationTile navTile) {
    final Angle dLat = placeNameService.getTileDelta().getLatitude();
    final Angle dLon = placeNameService.getTileDelta().getLongitude();

    // Determine the row and column offset from the global tiling origin for the southwest tile
    // corner
    int firstRow = Tile.computeRow(dLat, navTile.navSector.getMinLatitude());
    int firstCol = Tile.computeColumn(dLon, navTile.navSector.getMinLongitude());
    int lastRow = Tile.computeRow(dLat, navTile.navSector.getMaxLatitude().subtract(dLat));
    int lastCol = Tile.computeColumn(dLon, navTile.navSector.getMaxLongitude().subtract(dLon));

    int nLatTiles = lastRow - firstRow + 1;
    int nLonTiles = lastCol - firstCol + 1;

    Tile[] tiles = new Tile[nLatTiles * nLonTiles];

    Angle p1 = Tile.computeRowLatitude(firstRow, dLat);
    for (int row = 0; row <= lastRow - firstRow; row++) {
      Angle p2;
      p2 = p1.add(dLat);

      Angle t1 = Tile.computeColumnLongitude(firstCol, dLon);
      for (int col = 0; col <= lastCol - firstCol; col++) {
        Angle t2;
        t2 = t1.add(dLon);
        // Need offset row and column to correspond to total ro/col numbering
        tiles[col + row * nLonTiles] =
            new Tile(placeNameService, new Sector(p1, p2, t1, t2), row + firstRow, col + firstCol);
        t1 = t2;
      }
      p1 = p2;
    }

    return tiles;
  }
  @Override
  protected void doRender(DrawContext dc) {
    this.referencePoint = this.computeReferencePoint(dc);

    int serviceCount = this.placeNameServiceSet.getServiceCount();
    for (int i = 0; i < serviceCount; i++) {
      PlaceNameService placeNameService = this.placeNameServiceSet.getService(i);
      if (!isServiceVisible(dc, placeNameService)) continue;

      double minDistSquared =
          placeNameService.getMinDisplayDistance() * placeNameService.getMinDisplayDistance();
      double maxDistSquared =
          placeNameService.getMaxDisplayDistance() * placeNameService.getMaxDisplayDistance();

      if (isSectorVisible(
          dc, placeNameService.getMaskingSector(), minDistSquared, maxDistSquared)) {
        ArrayList<Tile> baseTiles = new ArrayList<Tile>();
        NavigationTile navTile = this.navTiles.get(i);
        // drill down into tiles to find bottom level navTiles visible
        List<NavigationTile> list = navTile.navTilesVisible(dc, minDistSquared, maxDistSquared);
        for (NavigationTile nt : list) {
          baseTiles.addAll(nt.getTiles());
        }

        for (Tile tile : baseTiles) {
          try {
            drawOrRequestTile(dc, tile, minDistSquared, maxDistSquared);
          } catch (Exception e) {
            Logging.logger()
                .log(
                    Level.FINE,
                    Logging.getMessage("layers.PlaceNameLayer.ExceptionRenderingTile"),
                    e);
          }
        }
      }
    }

    this.sendRequests();
    this.requestQ.clear();
  }