public VectorTile GetTile(int z, int x, int y)
{
var options = this.Options;
var extent = options.Extent;
var debug = options.Debug;
var z2 = 1 << z;
x = ((x % z2) + z2) % z2; // wrap tile x coordinate
var id = VectorTileCoord.ToID(z, x, y);
if (Tiles.Contains(id))
{
return(Transformer.TransformTile(Tiles.Get(id), extent));
}
// if (debug > 1) console.log('drilling down to z%d-%d-%d', z, x, y);
var z0 = z;
var x0 = x;
var y0 = y;
VectorTile parent = null;
while (parent.IsNull() && z0 > 0)
{
z0--;
x0 = (int)Math.Floor(x0 / 2.0);
y0 = (int)Math.Floor(y0 / 2.0);
var tileId = VectorTileCoord.ToID(z0, x0, y0);
parent = Tiles.Contains(tileId) ? Tiles.Get(tileId) : null;
}
if (parent.NoSource())
{
return(null);
}
// if we found a parent tile containing the original geometry, we can drill down from it
// if (debug > 1) console.log('found parent tile z%d-%d-%d', z0, x0, y0);
// it parent tile is a solid clipped square, return it instead since it's identical
if (IsClippedSquare(parent, extent, options.Buffer))
{
return(Transformer.TransformTile(parent, extent));
}
// if (debug > 1) console.time('drilling down');
var solid = SplitTile(parent.Source, new VectorTileCoord(z0, x0, y0), z, x, y);
// if (debug > 1) console.timeEnd('drilling down');
// one of the parent tiles was a solid clipped square
if (solid.HasValue)
{
double m = 1 << (z - solid.Value);
id = VectorTileCoord.ToID(solid.Value, (int)Math.Floor(x / m), (int)Math.Floor(y / m));
}
return(Tiles.Contains(id) ? Transformer.TransformTile(this.Tiles.Get(id), extent) : null);
}