public void Test_S2CellUnion_FromMinMax()
{
// Check the very first leaf cell and face cell.
S2CellId face1_id = S2CellId.FromFace(0);
TestFromMinMax(face1_id.RangeMin(), face1_id.RangeMin());
TestFromMinMax(face1_id.RangeMin(), face1_id.RangeMax());
// Check the very last leaf cell and face cell.
S2CellId face5_id = S2CellId.FromFace(5);
TestFromMinMax(face5_id.RangeMin(), face5_id.RangeMax());
TestFromMinMax(face5_id.RangeMax(), face5_id.RangeMax());
// Check random ranges of leaf cells.
for (int iter = 0; iter < 100; ++iter)
{
S2CellId x = S2Testing.GetRandomCellId(S2.kMaxCellLevel);
S2CellId y = S2Testing.GetRandomCellId(S2.kMaxCellLevel);
if (x > y)
{
var tmp = x; x = y; y = tmp;
}
TestFromMinMax(x, y);
}
}
public void Test_S2CellId_ParentChildRelationships()
{
S2CellId id = S2CellId.FromFacePosLevel(3, 0x12345678, S2.kMaxCellLevel - 4);
Assert.True(id.IsValid());
Assert.Equal(3UL, id.Face());
Assert.Equal(0x12345700UL, id.Pos());
Assert.Equal(S2.kMaxCellLevel - 4, id.Level());
Assert.False(id.IsLeaf());
Assert.Equal(0x12345610UL, id.ChildBegin(id.Level() + 2).Pos());
Assert.Equal(0x12345640UL, id.ChildBegin().Pos());
Assert.Equal(0x12345400UL, id.Parent().Pos());
Assert.Equal(0x12345000UL, id.Parent(id.Level() - 2).Pos());
// Check ordering of children relative to parents.
Assert.True(id.ChildBegin() < id);
Assert.True(id.ChildEnd() > id);
Assert.Equal(id.ChildEnd(), id.ChildBegin().Next().Next().Next().Next());
Assert.Equal(id.RangeMin(), id.ChildBegin(S2.kMaxCellLevel));
Assert.Equal(id.RangeMax().Next(), id.ChildEnd(S2.kMaxCellLevel));
// Check that cells are represented by the position of their center
// along the Hilbert curve.
Assert.Equal(2 * id.Id, id.RangeMin().Id + id.RangeMax().Id);
}
// Let T be the target S2CellId. If T is contained by some index cell I
// (including equality), this method positions the iterator at I and
// returns INDEXED. Otherwise if T contains one or more (smaller) index
// cells, it positions the iterator at the first such cell I and returns
// SUBDIVIDED. Otherwise it returns DISJOINT.
public (CellRelation cellRelation, int pos) LocateCell(S2CellId target)
{
// Let T be the target, let I = cell_map_.GetLowerBound(T.RangeMin), and
// let I' be the predecessor of I. If T contains any index cells, then T
// contains I. Similarly, if T is contained by an index cell, then the
// containing cell is either I or I'. We test for containment by comparing
// the ranges of leaf cells spanned by T, I, and I'.
var(pos, _) = SeekCell(target.RangeMin());
var id = GetCellId(pos);
if (id is not null)
{
if (id >= target && id.Value.RangeMin() <= target)
{
return(CellRelation.INDEXED, pos);
}
if (id <= target.RangeMax())
{
return(CellRelation.SUBDIVIDED, pos);
}
}
if (--pos >= 0)
{
id = GetCellId(pos);
if (id != null && id.Value.RangeMax() >= target)
{
return(CellRelation.INDEXED, pos);
}
}
return(CellRelation.DISJOINT, 0);
}
// Replaces all descendants of "id" in "covering" with "id".
// REQUIRES: "covering" contains at least one descendant of "id".
private static void ReplaceCellsWithAncestor(List <S2CellId> covering, S2CellId id)
{
var begin = covering.GetLowerBound(id.RangeMin());
var end = covering.GetUpperBound(id.RangeMax());
System.Diagnostics.Debug.Assert(begin != end);
covering.RemoveRange(begin + 1, end);
covering[begin] = id;
}