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;
}
}
private static S2Shape NewPaddedCell(S2CellId id, double padding_uv)
{
var ij = new int[2];
var face = id.ToFaceIJOrientation(out ij[0], out ij[1], out _, false);
var uv = S2CellId.IJLevelToBoundUV(ij, id.Level()).Expanded(padding_uv);
var vertices = new S2Point[4];
for (int i = 0; i < 4; ++i)
{
vertices[i] = S2.FaceUVtoXYZ(face, uv.GetVertex(i)).Normalize();
}
return(new S2LaxLoopShape(vertices));
}