7 * States/cities/roads overlays
13 x gis_update_tiles(tiles);
15 x if (need_split(tiles))
16 x tiles << split(tile)
17 x gis_render_surface(Image *img)
18 x polys = roam_get_intersecting_polies(img)
24 roam_update_errors(roam)
28 vertex_heght = roam->height_func()
34 x roam->height_func = srtm_height_func
35 x gis_update_tiles(tiles)
36 x for (new_tiles in tiles)
37 x points = roam_get_intersecting_points(tile)
43 x gis_update_tiles(tiles)
46 x gis_render_surface(gis, tile)