public static TileTreeNode BuildTree(TileInfo[] tiles)
{
var root = new TileTreeNode(90, -180, 180, 360);
//first level: 90°*90°
var firstLevel = CreateChildren(root, 2, 4).ToArray();
//second level: 30°*30°
var secondLevel = firstLevel.SelectMany(n => CreateChildren(n, 3, 3)).ToArray();
//third level: 10°*10°
var thirdLevel = secondLevel.SelectMany(n => CreateChildren(n, 3, 3)).ToArray();
//fourth level: 5°*2°
var fourthLevel = thirdLevel.SelectMany(n => CreateChildren(n, 2, 5)).ToArray();
//fourth level: 1°*1°
var fifthLevel = fourthLevel.SelectMany(n => CreateChildren(n, 5, 2)).ToArray();
foreach (var tile in tiles)
{
SetTileToNode(root, tile);
}
//Shake tree
root.RemoveEmptyChildren();
return(root);
}
private static IEnumerable <TileTreeNode> CreateChildren(TileTreeNode parentNode, int latitudeFraction, int longitudeFraction)
{
double latitudeSpan = parentNode.LatitudeSpan / latitudeFraction;
double longitudeSpan = parentNode.LongitudeSpan / longitudeFraction;
for (int i = 0; i < latitudeFraction; i++)
{
for (int j = 0; j < longitudeFraction; j++)
{
double north = parentNode.North - i * latitudeSpan;
double west = parentNode.West + j * longitudeSpan;
var child = new TileTreeNode(north, west, latitudeSpan, longitudeSpan);
parentNode.AddChildren(child);
yield return(child);
}
}
}
private static void SetTileToNode(TileTreeNode node, TileInfo tile)
{
if (!node.Intersect(tile))
{
return;
}
if (node.IsLeaf)
{
node.AddTile(tile);
return;
}
foreach (var childNode in node.Children)
{
SetTileToNode(childNode, tile);
}
}
public TileManager(ITileRepository repository, int maxCacheSize = MaxCacheSize)
{
_cache = new ElevationMapCache(repository, maxCacheSize);
_tileTreeRoot = TreeBuilder.BuildTree(repository.GetTiles());
}