#TODO: split: draw_single_runway(pos)
var draw_runways = func(group, apt,lod) {
   DEBUG and print("Drawing runways for:", apt.id);
   # var group = group.createChild("group", "apt-"~apt.id);
   # group = group.createChild("group", "runways");
   var rws_done = {};
      foreach(var rw; keys(apt.runways))
      {
        var is_heli = substr(rw, 0, 1) == "H";
        var rw_dir = is_heli ? nil : int(substr(rw, 0, 2));

        var rw_rec = "";
        var thresh_rec = 0;
        if( rw_dir != nil )
        {
          rw_rec = sprintf("%02d", math.mod(rw_dir - 18, 36));
          if( size(rw) == 3 )
          {
            var map_rec = {
              "R": "L",
              "L": "R",
              "C": "C"
            };
            rw_rec ~= map_rec[substr(rw, 2)];
          }

          if( rws_done[rw_rec] != nil )
            continue;

          var rw_rec = apt.runways[rw_rec];
          if( rw_rec != nil )
            thresh_rec = rw_rec.threshold;
        }

        rws_done[rw] = 1;

        rw = apt.runways[rw];
        
        var clr = SURFACECOLORS[rw.surface];
        if (clr == nil) { clr = SURFACECOLORS[0]};
        
        var icon_rw =
          group.createChild("path", "runway-" ~ rw.id)
                    .setStrokeLineWidth(0.5)
                    .setColor(1.0,1.0,1.0)
                    .setColorFill(clr.r, clr.g, clr.b);

        var rwy = Runway.new(rw);
        var beg_thr  = rwy.pointOffCenterline(rw.threshold);
        var beg_thr1 = rwy.pointOffCenterline(rw.threshold,  0.5 * rw.width);
        var beg_thr2 = rwy.pointOffCenterline(rw.threshold, -0.5 * rw.width);
        var beg1 = rwy.pointOffCenterline(0,  0.5 * rw.width);
        var beg2 = rwy.pointOffCenterline(0, -0.5 * rw.width);

        var end_thr  = rwy.pointOffCenterline(rw.length - thresh_rec);
        var end_thr1 = rwy.pointOffCenterline(rw.length - thresh_rec,  0.5 * rw.width);
        var end_thr2 = rwy.pointOffCenterline(rw.length - thresh_rec, -0.5 * rw.width);
        var end1 = rwy.pointOffCenterline(rw.length,  0.5 * rw.width);
        var end2 = rwy.pointOffCenterline(rw.length, -0.5 * rw.width);

        icon_rw.setDataGeo
        (
          [ canvas.Path.VG_MOVE_TO,
            canvas.Path.VG_LINE_TO,
            canvas.Path.VG_LINE_TO,
            canvas.Path.VG_LINE_TO,
            canvas.Path.VG_CLOSE_PATH ],
          [ beg1[0], beg1[1],
            beg2[0], beg2[1],
            end2[0], end2[1],
            end1[0], end1[1] ]
        );

        if( rw.length / rw.width > 3 and !is_heli )
        {
          # only runways which are much longer than wide are
          # real runways, otherwise it's probably a heliport.
          var icon_cl =
            group.createChild("path", "centerline")
                      .setStrokeLineWidth(0.5)
                      .setColor(1,1,1)
                      .setStrokeDashArray([15, 10]);

          icon_cl.setDataGeo
          (
            [ canvas.Path.VG_MOVE_TO,
              canvas.Path.VG_LINE_TO ],
            [ beg_thr[0], beg_thr[1],
              end_thr[0], end_thr[1] ]
          );

          var icon_thr =
            group.createChild("path", "threshold")
                      .setStrokeLineWidth(1.5)
                      .setColor(1,1,1);

          icon_thr.setDataGeo
          (
            [ canvas.Path.VG_MOVE_TO,
              canvas.Path.VG_LINE_TO,
              canvas.Path.VG_MOVE_TO,
              canvas.Path.VG_LINE_TO ],
            [ beg_thr1[0], beg_thr1[1],
              beg_thr2[0], beg_thr2[1],
              end_thr1[0], end_thr1[1],
              end_thr2[0], end_thr2[1] ]
          );
        }
      }
}