private readonly int orientation_; // Hilbert curve orientation of this cell (see s2coords.h)
#region Constructors
// Construct an S2PaddedCell for the given cell id and padding.
public S2PaddedCell(S2CellId id, double padding)
{
ij_lo_ = new int[2];
Id = id;
Padding = padding;
if (Id.IsFace())
{
// Fast path for constructing a top-level face (the most common case).
double limit = 1 + padding;
Bound = new R2Rect(new R1Interval(-limit, limit),
new R1Interval(-limit, limit));
middle_ = new R2Rect(new R1Interval(-padding, padding),
new R1Interval(-padding, padding));
ij_lo_[0] = ij_lo_[1] = 0;
orientation_ = (int)(Id.Face() & 1);
Level = 0;
}
else
{
var ij = new int[2];
id.ToFaceIJOrientation(out ij[0], out ij[1], out orientation_, true);
Level = id.Level();
Bound = S2CellId.IJLevelToBoundUV(ij, Level).Expanded(padding);
int ij_size = S2CellId.SizeIJ(Level);
ij_lo_[0] = ij[0] & -ij_size;
ij_lo_[1] = ij[1] & -ij_size;
}
}
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);
}
