public int?SplitTile(List <VectorTileFeature> startfeatures, VectorTileCoord startCoord, int?cz = null, int?cx = null, int?cy = null)
{
var stack = new Stack <GeoJsonVTStackItem>();
stack.Push(new GeoJsonVTStackItem {
Features = startfeatures, Coord = startCoord
});
int?solid = null;
while (stack.Count > 0)
{
var item = stack.Pop();
var features = item.Features;
var x = item.Coord.X;
var y = item.Coord.Y;
var z = item.Coord.Z;
var z2 = 1 << z;
var id = item.Coord.ToID();
VectorTile tile = Tiles.Contains(id) ? Tiles.Get(id) : null;
if (tile == null)
{
var tileTolerance = z == Options.MaxZoom ? 0 : Options.Tolerance / (z2 * Options.Extent);
tile = Tiles.Set(id, VectorTile.CreateTile(features, z2, x, y, tileTolerance, z == Options.MaxZoom));
Tiles.TileCoords.Add(new VectorTileCoord(z, x, y));
}
// save reference to original geometry in tile so that we can drill down later if we stop now
tile.Source = features;
// if it's the first-pass tiling
if (!cz.HasValue)
{
// stop tiling if we reached max zoom, or if the tile is too simple
if (z == Options.IndexMaxZoom || tile.NumPoints <= Options.IndexMaxPoints)
{
continue;
}
// if a drilldown to a specific tile
}
else
{
// stop tiling if we reached base zoom or our target tile zoom
if (z == Options.MaxZoom)
{
continue;
}
// stop tiling if it's not an ancestor of the target tile
if (cz.HasValue)
{
if (z == cz.Value)
{
continue;
}
var m = 1 << (cz.Value - z);
if (x != (int)Math.Floor((double)cx.Value / m) || y != (int)Math.Floor((double)cy.Value / m))
{
continue;
}
}
}
// stop tiling if the tile is solid clipped square
if (!Options.SolidChildren && IsClippedSquare(tile, Options.Extent, Options.Buffer))
{
if (cz.HasValue)
{
solid = z; // and remember the zoom if we're drilling down
}
continue;
}
// if we slice further down, no need to keep source geometry
tile.Source = null;
// if (debug > 1) console.time('clipping');
// values we'll use for clipping
var k1 = 0.5 * Options.Buffer / Options.Extent;
var k2 = 0.5 - k1;
var k3 = 0.5 + k1;
var k4 = 1 + k1;
List <VectorTileFeature> tl, bl, tr, br, left, right;
tl = bl = tr = br = null;
left = Clipper.Clip(features, z2, x - k1, x + k3, 0, IntersectX, tile.Min[0], tile.Max[0]);
right = Clipper.Clip(features, z2, x + k2, x + k4, 0, IntersectX, tile.Min[0], tile.Max[0]);
if (left.HasAny())
{
tl = Clipper.Clip(left, z2, y - k1, y + k3, 1, intersectY, tile.Min[1], tile.Max[1]);
bl = Clipper.Clip(left, z2, y + k2, y + k4, 1, intersectY, tile.Min[1], tile.Max[1]);
}
if (right.HasAny())
{
tr = Clipper.Clip(right, z2, y - k1, y + k3, 1, intersectY, tile.Min[1], tile.Max[1]);
br = Clipper.Clip(right, z2, y + k2, y + k4, 1, intersectY, tile.Min[1], tile.Max[1]);
}
// if (debug > 1) console.timeEnd('clipping');
if (tl.HasAny())
{
stack.Push(new GeoJsonVTStackItem {
Features = tl, Coord = new VectorTileCoord(z + 1, x * 2, y * 2)
});
}
if (bl.HasAny())
{
stack.Push(new GeoJsonVTStackItem {
Features = bl, Coord = new VectorTileCoord(z + 1, x * 2, y * 2 + 1)
});
}
if (tr.HasAny())
{
stack.Push(new GeoJsonVTStackItem {
Features = tr, Coord = new VectorTileCoord(z + 1, x * 2 + 1, y * 2)
});
}
if (br.HasAny())
{
stack.Push(new GeoJsonVTStackItem {
Features = br, Coord = new VectorTileCoord(z + 1, x * 2 + 1, y * 2 + 1)
});
}
}
return(solid);
}