/**
* Checks that "covering" completely covers the given region. If "check_tight"
* is true, also checks that it does not contain any cells that do not
* intersect the given region. ("id" is only used internally.)
*/
protected void checkCovering(IS2Region region, S2CellUnion covering, bool checkTight, S2CellId id)
{
if (!id.IsValid)
{
for (var face = 0; face < 6; ++face)
{
checkCovering(region, covering, checkTight, S2CellId.FromFacePosLevel(face, 0, 0));
}
return;
}
if (!region.MayIntersect(new S2Cell(id)))
{
// If region does not intersect id, then neither should the covering.
if (checkTight)
{
Assert.True(!covering.Intersects(id));
}
}
else if (!covering.Contains(id))
{
// The region may intersect id, but we can't assert that the covering
// intersects id because we may discover that the region does not actually
// intersect upon further subdivision. (MayIntersect is not exact.)
Assert.True(!region.Contains(new S2Cell(id)));
var result = !id.IsLeaf;
Assert.True(result);
var end = id.ChildEnd;
for (var child = id.ChildBegin; !child.Equals(end); child = child.Next)
{
checkCovering(region, covering, checkTight, child);
}
}
}
// Like GetSimpleCovering(), but accepts a starting S2CellId rather than a
// starting point and cell level. Returns all edge-connected cells at the
// same level as "start" that intersect "region", in arbitrary order.
public static void FloodFill(IS2Region region, S2CellId start, List <S2CellId> output)
{
var all = new List <(S2CellId, int)>();
var frontier = new List <S2CellId>();
output.Clear();
all.Add((start, start.GetHashCode()));
frontier.Add(start);
while (frontier.Any())
{
S2CellId id = frontier.Last();
frontier.RemoveAt(frontier.Count - 1);
if (!region.MayIntersect(new S2Cell(id)))
{
continue;
}
output.Add(id);
var neighbors = new S2CellId[4];
id.EdgeNeighbors(neighbors);
for (int edge = 0; edge < 4; ++edge)
{
var nbr = neighbors[edge];
var hash = nbr.GetHashCode();
all.Add((nbr, hash));
if (hash != 0)
{
frontier.Add(nbr);
}
}
}
}
/**
* Given a region and a starting cell, return the set of all the
* edge-connected cells at the same level that intersect "region". The output
* cells are returned in arbitrary order.
*/
private static void FloodFill(IS2Region region, S2CellId start, List <S2CellId> output)
{
var all = new HashSet <S2CellId>();
var frontier = new List <S2CellId>();
output.Clear();
all.Add(start);
frontier.Add(start);
while (frontier.Any())
{
var id = frontier[frontier.Count - 1];
frontier.RemoveAt(frontier.Count - 1);
if (!region.MayIntersect(new S2Cell(id)))
{
continue;
}
output.Add(id);
var neighbors = id.GetEdgeNeighbors();
for (var edge = 0; edge < 4; ++edge)
{
var nbr = neighbors[edge];
var hasNbr = all.Contains(nbr);
if (!all.Contains(nbr))
{
frontier.Add(nbr);
all.Add(nbr);
}
}
}
}
/**
* Checks that "covering" completely covers the given region. If "check_tight"
* is true, also checks that it does not contain any cells that do not
* intersect the given region. ("id" is only used internally.)
*/
protected void checkCovering(IS2Region region, S2CellUnion covering, bool checkTight, S2CellId id)
{
if (!id.IsValid)
{
for (var face = 0; face < 6; ++face)
{
checkCovering(region, covering, checkTight, S2CellId.FromFacePosLevel(face, 0, 0));
}
return;
}
if (!region.MayIntersect(new S2Cell(id)))
{
// If region does not intersect id, then neither should the covering.
if (checkTight)
{
Assert.True(!covering.Intersects(id));
}
}
else if (!covering.Contains(id))
{
// The region may intersect id, but we can't assert that the covering
// intersects id because we may discover that the region does not actually
// intersect upon further subdivision. (MayIntersect is not exact.)
Assert.True(!region.Contains(new S2Cell(id)));
var result = !id.IsLeaf;
Assert.True(result);
var end = id.ChildEnd;
for (var child = id.ChildBegin; !child.Equals(end); child = child.Next)
{
checkCovering(region, covering, checkTight, child);
}
}
}
